Updated on 2022/12/04

写真a

 
ITO, Etsuro
 
Scopus Paper Info  
Paper Count: 0  Citation Count: 0  h-index: 19

Citation count denotes the number of citations in papers published for a particular year.

Affiliation
Faculty of Education and Integrated Arts and Sciences, School of Education
Job title
Professor

Concurrent Post

  • Faculty of Science and Engineering   Graduate School of Advanced Science and Engineering

  • Affiliated organization   Global Education Center

Research Institute

  • 2020
    -
    2022

    理工学術院総合研究所   兼任研究員

Education

  •  
    -
    1989

    Waseda University  

  •  
    -
    1989

    Waseda University   Graduate School, Division of Science and Engineering  

  •  
    -
    1984

    Waseda University   School of Science and Engineering  

  •  
    -
    1984

    Waseda University   Faculty of Science and Engineering  

Degree

  • Waseda University   Doctor of Science

  • Waseda University   Master of Science

Research Experience

  • 2016.04
    -
    Now

    Waseda University   Department of Biology   Professor

  • 2006.04
    -
    2016.03

    Tokushima Bunri University   Kagawa School of Pharmaceutical Sciences   Professor

  • 1993
    -
    2006

    Hokkaido University

  • 1991
    -
    1993

    アメリカ合衆国国立衛生研究所 研究員

  • 1988
    -
    1991

    Waseda University

Professional Memberships

  •  
     
     

    国際神経行動学会(International Society for Neuroethology)

  •  
     
     

    日本比較生理生化学会

  •  
     
     

    北米神経科学会(Society for Neuroscience)

  •  
     
     

    日本動物学会

  •  
     
     

    日本生物物理学会

  •  
     
     

    日本神経科学学会

▼display all

 

Research Areas

  • Biophysics

  • Neuroscience-general

  • Animal physiological chemistry, physiology and behavioral biology

  • Pharmaceutical analytical chemistry and physicochemistry

  • Neuroscience-general

Research Interests

  • 物理系薬学

  • 神経科学一般

  • 生物物理学

  • 動物生理・行動

  • Biophysics

  • Neuroscience in General

  • Animal Physiology and Behavior

▼display all

Papers

  • CNS serotonin content mediating food deprivation-enhanced learning is regulated by hemolymph tryptophan concentration and autophagic flux in the pond snail

    Yuki Totani, Junko Nakai, Dai Hatakeyama, Varvara E. Dyakonova, Ken Lukowiak, Etsuro Ito

    Nutritional Neuroscience     1 - 11  2022.02

    DOI

  • Ultrasensitive Detection of SARS-CoV-2 Spike Proteins Using the Thio-NAD Cycling Reaction: A Preliminary Study before Clinical Trials.

    Yuta Kyosei, Mayuri Namba, Daiki Makioka, Ayumi Kokubun, Satoshi Watabe, Teruki Yoshimura, Tadahiro Sasaki, Tatsuo Shioda, Etsuro Ito

    Microorganisms   9 ( 11 )  2021.10  [International journal]

     View Summary

    To help control the global pandemic of coronavirus disease 2019 (COVID-19), we developed a diagnostic method targeting the spike protein of the virus that causes the infection, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). We applied an ultrasensitive method by combining a sandwich enzyme-linked immunosorbent assay (ELISA) and the thio-nicotinamide adenine dinucleotide (thio-NAD) cycling reaction to quantify spike S1 proteins. The limit of detection (LOD) was 2.62 × 10-19 moles/assay for recombinant S1 proteins and 2.6 × 106 RNA copies/assay for ultraviolet B-inactivated viruses. We have already shown that the ultrasensitive ELISA for nucleocapsid proteins can detect ultraviolet B-inactivated viruses at the 104 RNA copies/assay level, whereas the nucleocapsid proteins of SARS-CoV-2 are difficult to distinguish from those in conventional coronaviruses and SARS-CoV. Thus, an antigen test for only the nucleocapsid proteins is insufficient for virus specificity. Therefore, the use of a combination of tests against both spike and nucleocapsid proteins is recommended to increase both the detection sensitivity and testing accuracy of the COVID-19 antigen test. Taken together, our present study, in which we incorporate S1 detection by combining the ultrasensitive ELISA for nucleocapsid proteins, offers an ultrasensitive, antigen-specific test for COVID-19.

    DOI PubMed

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    4
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  • Improved detection sensitivity of an antigen test for SARS-CoV-2 nucleocapsid proteins with Thio-NAD cycling

    Yuta Kyosei, Mayuri Namba, Sou Yamura, Satoshi Watabe, Teruki Yoshimura, Tadahiro Sasaki, Tatsuo Shioda, Etsuro Ito

    Biological and Pharmaceutical Bulletin   44 ( 9 ) 1332  2021.09

     View Summary

    Antigen tests for infectious diseases are inexpensive and easy-to-use, but the limit of detection (LOD) is generally higher than that of PCR tests, which are considered the gold standard. In the present study, we combined a sandwich enzyme-linked immunosorbent assay (ELISA) with thionicotinamide-adenine dinucleotide (thio-NAD) cycling to improve the LOD of antigen tests for coronavirus disease 2019 (COVID-19). For recombinant nucleocapsid proteins of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the LOD of our ELISA with thio-NAD cycling was 2.95×10−17 moles/assay. When UV-irradiated inactive SARS-CoV-2 was used, the minimum detectable virions corresponding to 2.6×104 RNA copies/assay were obtained using our ELISA with thio-NAD cycling. The assay volume for each test was 100µL. The minimum detectable value was smaller than that of the latest antigen test using a fluorescent immunoassay for SARS-CoV-2, indicating the validity of our detection system for COVID-19 diagnosis.

    DOI PubMed

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    5
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  • Histone acetyltransferase activity of CREB-binding protein is essential for synaptic plasticity in Lymnaea

    Dai Hatakeyama, Hiroshi Sunada, Yuki Totani, Takayuki Watanabe, Ildikó Felletár, Adam Fitchett, Murat Eravci, Aikaterini Anagnostopoulou, Ryosuke Miki, Takashi Kuzuhara, Ildikó Kemenes, Etsuro Ito, György Kemenes

       2021.05

     View Summary

    <title>Abstract</title>In eukaryotes, CREB-binding protein (CBP), a coactivator of CREB, functions both as a platform for recruiting other components of the transcriptional machinery and as a histone acetyltransferase (HAT) that alters chromatin structure. We previously showed that the transcriptional activity of cAMP-responsive element binding protein (CREB) plays a crucial role in neuronal plasticity in the pond snail <italic>Lymnaea stagnalis</italic>. However, there is no information on the role how CBP plays in CREB-initiated plastic changes in <italic>Lymnaea</italic>. In this study, we characterized the <italic>Lymnaea</italic> CBP (LymCBP) gene and investigated the roles it plays in synaptic plasticity involved in regulating feeding behaviors. Similar to CBPs of other species, LymCBP possesses functional domains, such as KIX domain, which is essential for interaction with CREB and was shown to regulate long-term memory (LTM). <italic>In situ</italic> hybridization showed that the staining patterns of LymCBP mRNA in the central nervous system were very similar to those of <italic>Lymnaea</italic> CREB1 (LymCREB1). A particularly strong LymCBP mRNA signal was observed in the Cerebral Giant Cell (CGC), an identified extrinsic modulatory interneuron of the feeding circuit, key to both appetitive and aversive LTM for taste. Biochemical experiments using the recombinant protein of LymCBP HAT domain showed that its enzymatic activity was blocked by classical HAT inhibitors; i.e. curcumin, anacardic acid and garcinol. Preincubation of <italic>Lymnaea</italic> CNSs with these HAT inhibitors blocked cAMP-induced long-term potentiation between the CGC and the follower B1 motoneuron. We therefore suggest that HAT activity of LymCBP in the CGCs is a key factor in synaptic plasticity contributing to LTM after classical conditioning.

    DOI

  • Peripheral-neuron-like properties of differentiated human dental pulp stem cells (hDPSCs)

    Yuki Arimura, Yutaka Shindo, Ryu Yamanaka, Mai Mochizuki, Kohji Hotta, Taka Nakahara, Etsuro Ito, Tohru Yoshioka, Kotaro Oka

    PLOS ONE   16 ( 5 ) e0251356 - e0251356  2021.05

     View Summary

    Elucidating the mechanisms underlying human pain sensation requires the establishment of an <italic>in vitro</italic> model of pain reception comprising human cells expressing pain-sensing receptors and function properly as neurons. Human dental pulp stem cells (hDPSCs) are mesenchymal stem cells and a promising candidate for producing human neuronal cells, however, the functional properties of differentiated hDPSCs have not yet been fully characterized. In this study, we demonstrated neuronal differentiation of hDPSCs via both their expression of neuronal marker proteins and their neuronal function examined using Ca2+ imaging. Moreover, to confirm the ability of nociception, Ca2+ responses in differentiated hDPSCs were compared to those of rat dorsal root ganglion (DRG) neurons. Those cells showed similar responses to glutamate, ATP and agonists of transient receptor potential (TRP) channels. Since TRP channels are implicated in nociception, differentiated hDPSCs provide a useful <italic>in vitro</italic> model of human peripheral neuron response to stimuli interpreted as pain.

    DOI

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  • Activation of the orbitofrontal cortex by both meditation and exercise: A near-infrared spectroscopy study

    Shun Miyashiro, Yurika Yamada, Toshizumi Muta, Haruyuki Ishikawa, Tetsuri Abe, Masashi Hori, Kotaro Oka, Fusako Koshikawa, Etsuro Ito

    PLOS ONE   16 ( 2 ) e0247685 - e0247685  2021.02  [Refereed]  [International journal]

    Authorship:Corresponding author

     View Summary

    In some types of meditation, such as mindfulness and Zen, breathing is the focus of attention, whereas during an excessive, short-period of anaerobic exercise, the muscles become the focus of attention. Thus, during both efforts, one’s attention is focused on a certain feature of the body. Both meditation and exercise generally provide mental refreshment to humans. We hypothesized that the same brain regions are activated by both efforts in humans. To examine this hypothesis, we engaged participants in 3 tasks: meditation, exercise, and a control task. After each task, the participants underwent a 2-back test to concentrate their thoughts, while changes in their blood hemoglobin levels were simultaneously monitored using near-infrared spectroscopy (NIRS). Seventeen participants (20–24 years of age; 11 men, 6 women) were enrolled. We applied a fast-Fourier transform (FFT) analysis to the NIRS wave data and calculated the correlation coefficients of the FFT data between (1) meditation and control, (2) exercise and control, and (3) meditation and exercise, at the orbitofrontal cortex (OFC) and dorsolateral prefrontal cortex (DLPFC), brain areas that are generally involved in mental refreshment. A significant difference in the correlation coefficients between the OFC and DLPFC was detected in the meditation and exercise analysis, and signal source analysis confirmed that the NIRS waves spread from the right and left OFC edges (i.e., right and left temples) toward the center. Our results suggest that both meditation and exercise activate the OFC, which is involved in emotional reactions and motivation behavior, resulting in mental refreshment.

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    4
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  • Pain relief associated with decreased oxyhemoglobin level in left dorsolateral prefrontal cortex.

    Shun Miyashiro, Yurika Yamada, Masaru Nagaoka, Rei Shima, Toshizumi Muta, Haruyuki Ishikawa, Tetsuri Abe, Masashi Hori, Kotaro Oka, Fusako Koshikawa, Etsuro Ito

    PloS one   16 ( 8 ) e0256626  2021  [International journal]

     View Summary

    Pain in the elbow, shoulder, knee, lower back, and various other joints is relieved by adhesion of pyramidal thorn patches. To elucidate the pain relief mechanism induced by the patches, we established a quantitative method for estimating the pain reduction and investigated the brain regions that change in association with pain relief. We first attempted to quantify the pain relief using transcutaneous electric stimulation (TCES) and a visual analog scale (VAS), and then applied near-infrared spectroscopy (NIRS) to the prefrontal cortex, including the dorsolateral prefrontal cortex (DLPFC) and the orbitofrontal cortex (OFC). We also examined the salivary oxytocin levels, which are thought to reflect oxytocin secretion levels from the posterior pituitary in the brain. Application of pyramidal thorn patches to pain regions decreased the pain degree estimated using TCES and VAS. Oxyhemoglobin levels were likely to be decreased in the left DLPFC on the basis of NIRS measurements during patch treatment, suggesting that the left DLPFC is involved in pain relief. On the other hand, the salivary oxytocin levels varied widely. A potential reason for the varying salivary oxytocin levels is its utilization in the pain region as an analgesic agent. Our results suggest that the left DLPFC will become a target brain region for pain therapy.

    DOI PubMed

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    2
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  • Early diagnosis with ultrasensitive ELISA

    Etsuro Ito, Kanako Iha, Teruki Yoshimura, Kazunari Nakaishi, Satoshi Watabe

    Advances in Clinical Chemistry   101   121 - 133  2021

    Authorship:Lead author, Corresponding author

    DOI

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    13
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  • Antigen tests for COVID-19

    Yuta Kyosei, Sou Yamura, Mayuri Namba, Teruki Yoshimura, Satoshi Watabe, Etsuro Ito

    Biophysics and Physicobiology   18 ( 0 ) 28 - 39  2021  [Refereed]  [Invited]

    Authorship:Corresponding author

    DOI

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    14
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  • Quantum chemical calculation of intrinsic reaction coordinates from trans to cis structure of fluvoxamine

    Kei Odai, Tohru Sugimoto, Etsuro Ito

    Computational and Theoretical Chemistry   1192   113051 - 113051  2020.12  [Refereed]

    Authorship:Corresponding author

    DOI

    Scopus

  • Another Example of Conditioned Taste Aversion: Case of Snails

    Junko Nakai, Yuki Totani, Dai Hatakeyama, Varvara E. Dyakonova, Etsuro Ito

    Biology   9 ( 12 ) 422 - 422  2020.11  [Refereed]  [International journal]

    Authorship:Corresponding author

     View Summary

    Conditioned taste aversion (CTA) in mammals has several specific characteristics: (1) emergence of a negative symptom in subjects due to selective association with a taste-related stimulus, (2) robust long-term memory that is resistant to extinction induced by repeated presentation of the conditioned stimulus (CS), (3) a very-long-delay presentation of the unconditioned stimulus (US), and (4) single-trial learning. The pond snail, Lymnaea stagnalis, can also form a CTA. Although the negative symptoms, like nausea, in humans cannot be easily observed in invertebrate animal models of CTA, all the other characteristics of CTA seem to be present in snails. Selective associability was confirmed using a sweet sucrose solution and a bitter KCl solution. Once snails form a CTA, repeated presentation of the CS does not extinguish the CTA. A long interstimulus interval between the CS and US, like in trace conditioning, still results in the formation of a CTA in snails. Lastly, even single-trial learning has been demonstrated with a certain probability. In the present review, we compare, in detail, CTA in mammals and snails, and discuss the possible molecular events in CTA.

    DOI PubMed

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    6
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  • A threshold dosage of estrogen for male‐to‐female sex reversal in the Glandirana rugosa frog

    Akira Oike, Yoriko Nakamura, Shigeki Yasumasu, Etsuro Ito, Masahisa Nakamura

    Journal of Experimental Zoology Part A: Ecological and Integrative Physiology   333 ( 9 ) 652 - 659  2020.11  [Refereed]  [International journal]

     View Summary

    Steroid hormones play very important roles in gonadal differentiation in many vertebrate species. Previously, we have determined a threshold dosage of testosterone (T) to induce female-to-male sex reversal in Glandirana rugosa frogs. Genetic females formed a mixture of testis and ovary, the so-called ovotestis, when tadpoles of G. rugosa were reared in water containing the dosage of T, which enabled us to detect primary changes in the histology of the masculinizing gonads. In this study, we determined a threshold dosage of estradiol-17β (E2) to cause male-to-female sex reversal in this frog. We observed first signs of histological changes in the ovotestes, when tadpoles were reared in water containing the dosage of E2. Ovotestes were significantly larger than wild-type testes in size. By E2 treatment, male germ cells degenerated in the feminizing testis leading to their final disappearance. In parallel, oocytes appeared in the medulla of the ovotestis and later in the cortex as well. Quantitative polymerase chain reaction analysis revealed that the expression of sex-related genes involved in testis formation was significantly decreased in the ovotestis. In addition, immuno-positive signals of CYP17 that is involved in testis differentiation in this frog disappeared in the medulla first and then in the cortex. These results suggested that oocytes expanded in the feminizing gonad (ovary) contemporaneously with male germ cell disappearance. Primary changes in the histology of the gonads during male-to-female sex reversal occurred in the medulla and later in the cortex. This direction was opposite to that observed during female-to-male sex reversal in the G. rugosa frog.

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  • A novel, rapid (within hours) culture-free diagnostic method for detecting live Mycobacterium tuberculosis with high sensitivity

    Wen-Hung Wang, Rikiya Takeuchi, Shu-Huei Jain, Yong-Huang Jiang, Sonoko Watanuki, Yoshiharu Ohtaki, Kazunari Nakaishi, Satoshi Watabe, Po-Liang Lu, Etsuro Ito

    EBioMedicine   60   103007 - 103007  2020.10  [Refereed]

    Authorship:Corresponding author

     View Summary

    Background: Nucleic acid amplification tests (NAATs) are widely used to diagnose tuberculosis (TB), but cannot discriminate live bacilli from dead bacilli. Live bacilli can be isolated by culture methods, but this is time-consuming. We developed a de novo TB diagnostic method that detects only live bacilli with high sensitivity within hours.Methods: A prospective study was performed in Taiwan from 2017 to 2018. Sputum was collected consecutively from 1102 patients with suspected TB infection. The sputum was pretreated and heated at 46 degrees C for 1 h to induce the secretion of MPT64 protein from live Mycobacterium tuberculosis. MPT64 was detected with our ultrasensitive enzyme-linked immunosorbent assay (ELISA) coupled with thionicotinamide-adenine dinucleotide (thio-NAD) cycling. We compared our data with those obtained using a culture test (MGIT), a smear test (Kinyoun staining), and a NAAT (Xpert).Findings: The limit of detection for MPT64 in our culture-free ultrasensitive ELISA was 2.0 x 10(-19) moles/assay. When the criterion for a positive response was set as an absorbance value >= 17 mAbs, this value corresponded to ca. 330 CFU/mL in the culture method - almost the same high-detection sensitivity as the culture method. To confirm that MPT64 is secreted from only live bacilli, M. bovis BCG was killed using 8 mg/mL rifampicin and then heated. Following this procedure, our method detected no MPT64. Our rapid ultra-sensitive ELISA-based method required only 5 h to complete. Comparing the results of our method with those of culture tests for 944 specimens revealed a sensitivity of 86.9% (93/107, 95% CI: 79.0-92.7%) and a specificity of 92.0% (770/837, 95% CI: 89.9-93.7%). The performance data were not significantly different (McNemar's test, P = 0.887) from those of the Xpert tests. In addition, at a >= 1+ titer in the smear test, the positive predictive value of our culture-free ultrasensitive ELISA tests was in a good agreement with that of the culture tests. Furthermore, our culture-free ultrasensitive ELISA test had better validity for drug effectiveness examination than Xpert tests because our test detected only live bacilli. Interpretation: Our culture-free ultrasensitive ELISA method detects only live TB bacilli with high sensitivity within hours, allowing for rapid diagnosis of TB and monitoring drug efficacy.Funding: Matching Planner Program from JST (VP29117939087), the A-STEP Program from JST (AS3015096U), Waseda University grants for Specific Research Projects (2017A-015 and 2019C-123), the Precise Measurement Technology Promotion Foundation to E.I. (c) 2020 The Author(s). Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/)

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  • Proposal of De Novo Antigen Test for COVID-19: Ultrasensitive Detection of Spike Proteins of SARS-CoV-2

    Yuta Kyosei, Mayuri Namba, Sou Yamura, Rikiya Takeuchi, Noriko Aoki, Kazunari Nakaishi, Satoshi Watabe, Etsuro Ito

    Diagnostics   10 ( 8 ) 594 - 594  2020.08  [Refereed]

    Authorship:Corresponding author

     View Summary

    Polymerase chain reaction (PCR)-based antigen tests are technically difficult, time-consuming, and expensive, and may produce false negative results requiring follow-up confirmation with computed tomography. The global coronavirus disease 2019 (COVID-19) pandemic has increased the demand for accurate, easy-to-use, rapid, and cost-effective antigen tests for clinical application. We propose a de novo antigen test for diagnosing COVID-19 using the combination of sandwich enzyme-linked immunosorbent assay and thio-nicotinamide adenine dinucleotide (thio-NAD) cycling. Our test takes advantage of the spike proteins specific to the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) virus. The limit of detection of our test was 2.3 × 10−18 moles/assay. If the virus has ~25 spike proteins on its surface, our method should detect on the order of 10−20 moles of virus/assay, corresponding to ~104 copies of the virus RNA/assay. The detection sensitivity approaches that of PCR-based assays because the average virus RNA load used for PCR-based assays is ~105 copies per oro- or naso-pharyngeal swab specimen. To our knowledge, this is the first ultrasensitive antigen test for SARS-CoV-2 spike proteins that can be performed with an easy-to-use microplate reader. Sufficient sensitivity can be achieved within 10 min of thio-NAD cycling. Our antigen test allows for rapid, cost-effective, specific, ultrasensitive, and simultaneous multiple measurements of SARS-CoV-2, and has broad application for the diagnosis for COVID-19.

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    28
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  • Clinical Significance of Electronegative Low-Density Lipoprotein Cholesterol in Atherothrombosis

    Chih-Sheng Chu, Shi Hui Law, David Lenzen, Yong-Hong Tan, Shih-Feng Weng, Etsuro Ito, Jung-Chou Wu, Chu-Huang Chen, Hua-Chen Chan, Liang-Yin Ke

    Biomedicines   8 ( 8 ) 254 - 254  2020.07  [Refereed]

     View Summary

    Despite the numerous risk factors for atherosclerotic cardiovascular diseases (ASCVD), cumulative evidence shows that electronegative low-density lipoprotein (L5 LDL) cholesterol is a promising biomarker. Its toxicity may contribute to atherothrombotic events. Notably, plasma L5 LDL levels positively correlate with the increasing severity of cardiovascular diseases. In contrast, traditional markers such as LDL-cholesterol and triglyceride are the therapeutic goals in secondary prevention for ASCVD, but that is controversial in primary prevention for patients with low risk. In this review, we point out the clinical significance and pathophysiological mechanisms of L5 LDL, and the clinical applications of L5 LDL levels in ASCVD can be confidently addressed. Based on the previously defined cut-off value by receiver operating characteristic curve, the acceptable physiological range of L5 concentration is proposed to be below 1.7 mg/dL. When L5 LDL level surpass this threshold, clinically relevant ASCVD might be present, and further exams such as carotid intima-media thickness, pulse wave velocity, exercise stress test, or multidetector computed tomography are required. Notably, the ultimate goal of L5 LDL concentration is lower than 1.7 mg/dL. Instead, with L5 LDL greater than 1.7 mg/dL, lipid-lowering treatment may be required, including statin, ezetimibe or PCSK9 inhibitor, regardless of the low-density lipoprotein cholesterol (LDL-C) level. Since L5 LDL could be a promising biomarker, we propose that a high throughput, clinically feasible methodology is urgently required not only for conducting a prospective, large population study but for developing therapeutics strategies to decrease L5 LDL in the blood.

    DOI

  • Impact of Insulin on Memory Recall

    Yuki Totani, Junko Nakai, Etsuro Ito

    Journal of Data Mining in Genomics & Proteomics   11   225  2020.07  [Refereed]

    Authorship:Corresponding author

  • Features of behavioral changes underlying conditioned taste aversion in the pond snail Lymnaea stagnalis

    Junko Nakai, Yuki Totani, Satoshi Kojima, Manabu Sakakibara, Etsuro Ito

    Invertebrate Neuroscience   20 ( 2 ) 8 - 8  2020.06  [International journal]

    Authorship:Corresponding author

     View Summary

    Conditioned taste aversion (CTA) in the freshwater pulmonate Lymnaea stagnalis can be formed by presenting ten pairings of sucrose as the conditioned stimulus (CS) and KCl as the unconditioned stimulus (US). The CTA is consolidated to long-term memory (LTM) lasting longer than a month. In the present study, we examined the time course of protein synthesis-dependent period during the consolidation of Lymnaea CTA to LTM by pharmacological inhibition of transcription or translation. The robustness for CTA-LTM was then examined by extinction trials, i.e., repeated presentations of the CS alone. Furthermore, we evaluated the effects of the interstimulus interval (ISI) between the presentation of the CS and US. Our findings indicated that the protein synthesis-dependent period coincides with the CTA training. Repeated presentations of the CS alone after establishment of CTA did not extinguish the CTA, demonstrating the robustness of the CTA-LTM. The ISI ranged from 10 s to a few minutes, and there was no inverted U-shaped function between the ISI and the conditioned response (i.e., suppression of feeding). Thus, CTA still formed even when the presentation of the US was delayed. These features of Lymnaea CTA complement the knowledge for mammalian CTA.

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  • Identifying the Therapeutic Significance of Mesenchymal Stem Cells

    Vineet Kumar Mishra, Hui-Hsuan Shih, Farzana Parveen, David Lenzen, Etsuro Ito, Te-Fu Chan, Liang-Yin Ke

    Cells   9 ( 5 ) 1145 - 1145  2020.05

     View Summary

    The pleiotropic behavior of mesenchymal stem cells (MSCs) has gained global attention due to their immense potential for immunosuppression and their therapeutic role in immune disorders. MSCs migrate towards inflamed microenvironments, produce anti-inflammatory cytokines and conceal themselves from the innate immune system. These signatures are the reason for the uprising in the sciences of cellular therapy in the last decades. Irrespective of their therapeutic role in immune disorders, some factors limit beneficial effects such as inconsistency of cell characteristics, erratic protocols, deviating dosages, and diverse transfusion patterns. Conclusive protocols for cell culture, differentiation, expansion, and cryopreservation of MSCs are of the utmost importance for a better understanding of MSCs in therapeutic applications. In this review, we address the immunomodulatory properties and immunosuppressive actions of MSCs. Also, we sum up the results of the enhancement, utilization, and therapeutic responses of MSCs in treating inflammatory diseases, metabolic disorders and diabetes.

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  • A Phylogenetically Distinct Group of Glandirana rugosa Found in Kyushu, Japan

    Akira Oike, Masatake Mochizuki, Koji Tojo, Takanori Matsuo, Yoriko Nakamura, Shigeki Yasumasu, Etsuro Ito, Takayuki Arai, Masahisa Nakamura

    Zoological Science   37 ( 2 ) 193 - 193  2020.04  [Refereed]  [Domestic journal]

     View Summary

    The Japanese wrinkled frog Glandirana rugosa is separated into five genetically different groups. One group in western Japan is further divided into three subgroups, found in Kyushu, Shikoku, and western Honshu. We collected G. rugosa frogs at 39 sites in Kyushu and determined nucleotide sequences of the mitochondrial 12S and 16S rRNA genes for phylogenetic analysis. Unexpectedly, we found a group of frogs in southeastern Kyushu that did not cluster with any of the pre-existing five groups of G. rugosa on the phylogenetic trees. The frogs in the new group and G. rugosa in Kyushu were externally similar, but there were a few significant differences in morphological features between the two populations. In addition, we observed significant differences in the frogs' calls . Thus, the group of the frogs in southeastern Kyushu may represent a new candidate species in the genus Glandirana. We discuss the possibility of a new species.

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  • The Role of Serotonin in the Influence of Intense Locomotion on the Behavior Under Uncertainty in the Mollusk Lymnaea stagnalis

    Hitoshi Aonuma, Maxim Mezheritskiy, Boris Boldyshev, Yuki Totani, Dmitry Vorontsov, Igor Zakharov, Etsuro Ito, Varvara Dyakonova

    Frontiers in Physiology   11   221 - 221  2020.03  [Refereed]  [International journal]

     View Summary

    The role of serotonin in the immediate and delayed influence of physical exercise on brain functions has been intensively studied in mammals. Recently, immediate effects of intense locomotion on the decision-making under uncertainty were reported in the Great Pond snail, Lymnaea stagnalis (Korshunova et al., 2016). In this animal, serotonergic neurons control locomotion, and serotonin modulates many processes underlying behavior, including cognitive ones (memory and learning). Whether serotonin mediates the behavioral effects of intense locomotion in mollusks, as it does in vertebrates, remains unknown. Here, the delayed facilitating effects of intense locomotion on the decision-making in the novel environment are described in Lymnaea. Past exercise was found to alter the metabolism of serotonin, namely the content of serotonin precursor and its catabolites in the cerebral and pedal ganglia, as measured by high-performance liquid chromatography. The immediate and delayed effects of exercise on serotonin metabolism were different. Moreover, serotonin metabolism was regulated differently in different ganglia. Pharmacological manipulations of the serotonin content and receptor availability suggests that serotonin is likely to be responsible for the locomotor acceleration in the test of decision-making under uncertainty performed after exercise. However, the exercise-induced facilitation of decision-making (manifested in a reduced number of turns during the orienting behavior) cannot be attributed to the effects of serotonin.

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  • Induction of LTM following an Insulin Injection

    Yuki Totani, Junko Nakai, Varvara E. Dyakonova, Ken Lukowiak, Manabu Sakakibara, Etsuro Ito

    eneuro   7 ( 2 ) ENEURO.0088 - 20.2020  2020.03

    Authorship:Corresponding author

    DOI

  • Memory-enhancing effects of short-term fasting

    Y. Totani, J. Nakai, D. Hatakeyama, E. Ito

    The European Zoological Journal   87 ( 1 ) 597 - 602  2020.01  [Refereed]

    Authorship:Corresponding author

    DOI

  • Rapid differentiation of human dental pulp stem cells to neuron-like cells by high K+ stimulation

    Yuki Kogo, Chiaki Seto, Yuki Totani, Mai Mochizuki, Taka Nakahara, Kotaro Oka, Tohru Yoshioka, Etsuro Ito

    Biophysics and Physicobiology   17   132 - 139  2020  [Refereed]  [Domestic journal]

    Authorship:Corresponding author

     View Summary

    As human-origin cells, human dental pulp stem cells (hDPSCs) are thought to be potentially useful for biological and medical experiments. They are easily obtained from lost primary teeth or extracted wisdom teeth, and they are mesenchymal stem cells that are known to differentiate into osteoblasts, chondrocytes, and adipocytes. Although hDPSCs originate from neural crest cells, it is difficult to induce hDPSCs to differentiate into neuron-like cells. To facilitate their differentiation into neuron-like cells, we evaluated various differentiation conditions. Activation of K+ channels is thought to regulate the intracellular Ca2+ concentration, allowing for manipulation of the cell cycle to induce the differentiation of hDPSCs. Therefore, in addition to a conventional neural cell differentiation protocol, we activated K+ channels in hDPSCs. Immunocyto-chemistry and real-time PCR revealed that applying a combination of 3 stimuli (high K+ solution, epigenetic reprogramming solution, and neural differentiation solution) to hDPSCs increased their expression of neuronal markers, such as β3-tubulin, postsynaptic density protein 95, and nestin within 5 days, which led to their rapid differentiation into neuron-like cells. Our findings indicate that epigenetic reprogramming along with cell cycle regulation by stimulation with high K+ accelerated the differentiation of hDPSCs into neuron-like cells. Therefore, hDPSCs can be used in various ways as neuron-like cells by manipulating their cell cycle.

    DOI PubMed

  • Sex Reversal Induced by Steroid Hormones in Glandirana rugosa Frogs

    Masahisa Nakamura, Akira Oike, Etsuro Ito

    JSM Sexual Medicine   4   1056  2020  [Refereed]

    Authorship:Last author

  • Real-time Analysis of Animal Feeding Behavior with a Low-calculation-power CPU.

    Yuki Totani, Susumu Kotani, Kei Odai, Etsuro Ito, Manabu Sakakibara

    IEEE transactions on bio-medical engineering    2019.08  [Refereed]  [International journal]

     View Summary

    Our goal was to develop an automated system to determine whether animals have learned and changed their behavior in real-time using a low calculation-power central processing unit (CPU). The bottleneck of real-time analysis is the speed of image recognition. For fast image recognition, 99.5% of the image was excluded from image recognition by distinguishing between the subject and the background. We achieved this by applying a binarization and connected-component labeling technique. This task is important for developing a fully automated learning apparatus. The use of such an automated system can improve the efficiency and accuracy of biological studies. The pond snail Lymnaea stagnalis can be classically conditioned to avoid food that naturally elicits feeding behavior, and to consolidate this aversion into long-term memory. Determining memory status in the snail requires real-time analysis of the number of bites the snail makes in response to food presentation. The main algorithm for counting bites comprises two parts: extracting the mouth images from the recorded video and measuring the bite rate corresponding to the memory status. Reinforcement-supervised learning and image recognition were used to extract the mouth images. A change in the size of the mouth area was used as the cue for counting the number of bites. The accuracy of the final judgment of whether or not the snail had learned was the same as that determined by human observation. This method to improve the processing speed of image recognition has the potential for broad application beyond biological fields.

    DOI PubMed

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    5
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  • A novel role of oxytocin: Oxytocin-induced well-being in humans

    ITO Etsuro

    Biophys Physicobiol   16   132 - 139  2019.08  [Refereed]

  • Ab-initio study of pyrrole ring deformation in the indole group of 5-HT interacting with water molecules

    ITO Etsuro

    Biophys Physicobiol   16   127 - 131  2019.08  [Refereed]

  • Ultrasensitive ELISA Developed for Diagnosis.

    Kanako Iha, Mikio Inada, Naoki Kawada, Kazunari Nakaishi, Satoshi Watabe, Yong Hong Tan, Chieh Shen, Liang-Yin Ke, Teruki Yoshimura, Etsuro Ito

    Diagnostics (Basel, Switzerland)   9 ( 3 ) E78  2019.07  [Refereed]  [International journal]

     View Summary

    For the diagnosis of disease, the ability to quantitatively detect trace amounts of the causal proteins from bacteria/viruses as biomarkers in patient specimens is highly desirable. Here we introduce a simple, rapid, and colorimetric assay as a de novo, ultrasensitive detection method. This ultrasensitive assay consists of a sandwich enzyme-linked immunosorbent assay (ELISA) and thionicotinamide-adenine dinucleotide (thio-NAD) cycling, forming an ultrasensitive ELISA, in which the signal substrate (i.e., thio-NADH) accumulates in a triangular manner, and the accumulated thio-NADH is measured at its maximum absorption wavelength of 405 nm. We have successfully achieved a limit of detection of ca. 10-18 moles/assay for a target protein. As an example of infectious disease detection, HIV-1 p24 could be measured at 0.0065 IU/assay (i.e., 10-18 moles/assay), and as a marker for a lifestyle-related disease, adiponectin could be detected at 2.3 × 10-19 moles/assay. In particular, despite the long-held belief that the trace amounts of adiponectin in urine can only be detected using a radioisotope, our ultrasensitive ELISA was able to detect urinary adiponectin. This method is highly versatile because simply changing the antibody enables the detection of various proteins. This assay system requires only the measurement of absorbance, thus it requires equipment that is easily obtained by medical facilities, which facilitates diagnosis in hospitals and clinics. Moreover, we describe an expansion of our ultrasensitive ELISA to a non-amplification nucleic acid detection method for nucleic acids using hybridization. These de novo methods will enable simple, rapid, and accurate diagnosis.

    DOI PubMed

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    28
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  • Urinary adiponectin as a new diagnostic index for chronic kidney disease due to diabetic nephropathy

    ITO Etsuro

    BMJ Open Diabetes Res Care   7 ( 1 ) e000661  2019.05  [Refereed]

  • Immunochromatographic detection of MPB64 secreted from active BCG by heating: toward same-day diagnosis of tuberculosis

    ITO Etsuro

    Biotechniques   66 ( 5 ) 240 - 242  2019.05  [Refereed]

  • Adhesive pyramidal thorn patches provide pain relief to athletes

    ITO Etsuro

    Kaohsiung J Med Sci   35 ( 4 ) 230 - 237  2019.04  [Refereed]

  • Relaxin-3 regulates corticotropin-releasing factor gene expression in cultured rat hypothalamic 4B cells.

    Hiroko Yagi, Kazunori Kageyama, Noriko Kinoshita, Kanako Niioka, Satoshi Yamagata, Etsuro Ito, Makoto Daimon

    Neuroscience letters   692   137 - 142  2019.01  [Refereed]  [International journal]

     View Summary

    The ancestral insulin/relaxin peptide superfamily member relaxin-3 is an important regulator of food intake and behaviors related to anxiety and motivation. Relaxin family peptide receptor 1 (RXFP1) and RXFP3 are expressed in the rat hypothalamic paraventricular nucleus (PVN). Corticotropin-releasing factor (CRF) is produced in the PVN in response to stressors and promotes adrenocorticotropic hormone secretion from the anterior pituitary. We hypothesized that relaxin-3 directly regulates Crf expression in the hypothalamus and investigated its effect on Crf expression in cultured hypothalamic 4B cells. Relaxin-3 increased Crf mRNA levels and stimulated Crf promoter activity. Both protein kinase A and C pathways contributed to relaxin-3-induced Crf promoter activity. Rxfp1 and Rxfp3 mRNA and their proteins were expressed in cultured hypothalamic 4B cells. Relaxin-3 decreased Rxfp1 mRNA and protein levels and increased Rxfp3 mRNA and protein levels. These results suggested that the action of relaxin-3 in cultured hypothalamic 4B cells may be regulated through both RXFP1 and RXFP3.

    DOI PubMed

  • Monoamines, Insulin and the Roles They Play in Associative Learning in Pond Snails.

    Yuki Totani, Hitoshi Aonuma, Akira Oike, Takayuki Watanabe, Dai Hatakeyama, Manabu Sakakibara, Ken Lukowiak, Etsuro Ito

    Frontiers in behavioral neuroscience   13   65 - 65  2019  [Refereed]  [International journal]

     View Summary

    Molluscan gastropods have long been used for studying the cellular and molecular mechanisms underlying learning and memory. One such gastropod, the pond snail Lymnaea stagnalis, exhibits long-term memory (LTM) following both classical and operant conditioning. Using Lymnaea, we have successfully elucidated cellular mechanisms of learning and memory utilizing an aversive classical conditioning procedure, conditioned taste aversion (CTA). Here, we present the behavioral changes following CTA training and show that the memory score depends on the duration of food deprivation. Then, we describe the relationship between the memory scores and the monoamine contents of the central nervous system (CNS). A comparison of learning capability in two different strains of Lymnaea, as well as the filial 1 (F1) cross from the two strains, presents how the memory scores are correlated in these populations with monoamine contents. Overall, when the memory scores are better, the monoamine contents of the CNS are lower. We also found that as the insulin content of the CNS decreases so does the monoamine contents which are correlated with higher memory scores. The present review deepens the relationship between monoamine and insulin contents with the memory score.

    DOI PubMed

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  • Effects of 5-HT and insulin on learning and memory formation in food-deprived snails.

    Hitoshi Aonuma, Yuki Totani, Mugiho Kaneda, Ryota Nakamura, Takayuki Watanabe, Dai Hatakeyama, Varvara E Dyakonova, Ken Lukowiak, Etsuro Ito

    Neurobiology of learning and memory   148   20 - 29  2018.02  [Refereed]  [International journal]

     View Summary

    The pond snail Lymnaea stagnalis learns conditioned taste aversion (CTA) and consolidates it into long-term memory (LTM). How well they learn and form memory depends on the degree of food deprivation. Serotonin (5-HT) plays an important role in mediating feeding, and insulin enhances the memory consolidation process following CTA training. However, the relationship between these two signaling pathways has not been addressed. We measured the 5-HT content in the central nervous system (CNS) of snails subjected to different durations of food deprivation. One-day food-deprived snails, which exhibit the best learning and memory, had the lowest 5-HT content in the CNS, whereas 5-day food-deprived snails, which do not learn, had a high 5-HT content. Immersing 1-day food-deprived snails in 5-HT impaired learning and memory by causing an increase in 5-HT content, and that the injection of insulin into these snails reversed this impairment. We conclude that insulin rescues the CTA deficit and this may be due to a decrease in the 5-HT content in the CNS of Lymnaea.

    DOI PubMed

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    14
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  • A Proposed Molecular Mechanism for Physical Analgesia in Chronic Pain.

    Saito N, Shima R, Yamada Y, Nagaoka M, Ito E, Yoshioka T

    Neural plasticity   2018   1260285  2018  [Refereed]

    DOI PubMed

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    11
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  • Comparison of brain monoamine content in three populations of Lymnaea that correlates with taste-aversive learning ability.

    Hitoshi Aonuma, Yuki Totani, Manabu Sakakibara, Ken Lukowiak, Etsuro Ito

    Biophysics and physicobiology   15   129 - 135  2018  [Refereed]  [Domestic journal]

     View Summary

    To find a causal mechanism of learning and memory is a heuristically important topic in neuroscience. In the pond snail Lymnaea stagnalis, the following experimental facts have accrued regarding a classical conditioning procedure known as conditioned taste aversion (CTA): (1) one-day food-deprived Dutch snails have superior CTA memory formation; (2) the one-day food-deprived snails have a low monoamine content (e.g., serotonin, dopamine, octopamine) in their central nervous system (CNS); (3) fed or five-day food-deprived snails have poorer CTA memory and a higher monoamine content; (4) the Dutch snails form better CTA memory than the Canadian TC1 strain; and, (5) the F1 cross snails between the Dutch and Canadian TC1 strains also form poor CTA memory. Here, in one-day food-deprived snails, we measured the monoamine content in the CNSs of the 3 populations. In most instances, the monoamine content of the Dutch strain was lower than in the other two populations. The F1 cross snails had the highest monoamine content. A lower monoamine content is correlated with the better CTA memory formation.

    DOI PubMed

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    7
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  • Pharmacological effects of cannabinoids on learning and memory in Lymnaea

    Hiroshi Sunada, Takayuki Watanabe, Dai Hatakeyama, Sangmin Lee, Jeremy Forest, Manabu Sakakibara, Etsuro Ito, Ken Lukowiak

    JOURNAL OF EXPERIMENTAL BIOLOGY   220 ( 17 ) 3026 - 3038  2017.09  [Refereed]

     View Summary

    Cannabinoids are hypothesized to play an important role in modulating learning and memory formation. Here, we identified mRNAs expressed in Lymnaea stagnalis central nervous system that encode two G-protein-coupled receptors (Lymnaea CBr-like 1 and 2) that structurally resemble mammalian cannabinoid receptors (CBrs). We found that injection of a mammalian CBr agonist WIN 55,212-2 (WIN 55) into the snail before operant conditioning obstructed learning and memory formation. This effect of WIN 55 injection persisted for at least 4 days following its injection. A similar obstruction of learning and memory occurred when a severe traumatic stimulus was delivered to L. stagnalis. In contrast, injection of a mammalian CBr antagonist AM 251 enhanced long-term memory formation in snails and reduced the duration of the effects of the severe traumatic stressor on learning and memory. Neither WIN 55 nor AM 251 altered normal homeostatic aerial respiratory behaviour elicited in hypoxic conditions. Our results suggest that putative cannabinoid receptors mediate stressful stimuli that alter learning and memory formation in Lymnaea. This is also the first demonstration that putative CBrs are present in Lymnaea and play a key role in learning and memory formation.

    DOI PubMed

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    16
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  • Origin of sex chromosomes in six groups of Rana rugosa frogs inferred from a sex-linked DNA marker

    Akira Oike, Koichiro Watanabe, Mi-Sook Min, Koji Tojo, Masahide Kumagai, Yuya Kimoto, Tadashi Yamashiro, Takanori Matsuo, Maho Kodama, Yoriko Nakamura, Masaru Notsu, Takeyoshi Tochimoto, Hiroyuki Fujita, Maki Ota, Etsuro Ito, Shigeki Yasumasu, Masahisa Nakamura

    JOURNAL OF EXPERIMENTAL ZOOLOGY PART A-ECOLOGICAL AND INTEGRATIVE PHYSIOLOGY   327 ( 7 ) 444 - 452  2017.08  [Refereed]

     View Summary

    Each vertebrate species, as a general rule, has either the XX/XY or ZZ/ZW chromosomes by which sex is determined. However, the Japanese Rana (R.) rugosa frog is an exception, possessing both sex-determining combinations within one species, varying with region of origin. We collected R. rugosa frogs from 104 sites around Japan and South Korea and determined the nucleotide sequences of the mitochondrial 12S ribosomal RNA gene. Based on the sequences, R. rugosa frogs were divided into four groups from Japan and one from South Korea. The ZZ/ZW type is reportedly derived from the XX/XY type, although recently a new ZZ/ZW type of R. rugosa was reported. However, it still remains unclear from where the sex chromosomes in the five groups of this species were derived. In this study, we successfully isolated a sex-linked DNA maker and used it to classify R. rugosa frogs into several groupings. From the DNA marker as well as from nucleotide analysis of the promoter region of the androgen receptor (AR) gene, we identified another female heterogametic group, designated, West-Central. The sex chromosomes in the West-Central originated from the West and Central groups. The results indicate that a sex-linked DNA marker is a verifiable tool to determine the origin of the sex chromosomes in R. rugosa frogs in which the sex-determining system has changed, during two independent events, from the male to female heterogamety.

    DOI

    Scopus

    9
    Citation
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  • Origin of sex chromosomes in six groups of Rana rugosa frogs inferred from a sex-linked DNA marker.

    Akira Oike, Koichiro Watanabe, Mi-Sook Min, Koji Tojo, Masahide Kumagai, Yuya Kimoto, Tadashi Yamashiro, Takanori Matsuo, Maho Kodama, Yoriko Nakamura, Masaru Notsu, Takeyoshi Tochimoto, Hiroyuki Fujita, Maki Ota, Etsuro Ito, Shigeki Yasumasu, Masahisa Nakamura

    Journal of experimental zoology. Part A, Ecological and integrative physiology   327 ( 7 ) 444 - 452  2017.08  [Refereed]  [International journal]

     View Summary

    Each vertebrate species, as a general rule, has either the XX/XY or ZZ/ZW chromosomes by which sex is determined. However, the Japanese Rana (R.) rugosa frog is an exception, possessing both sex-determining combinations within one species, varying with region of origin. We collected R. rugosa frogs from 104 sites around Japan and South Korea and determined the nucleotide sequences of the mitochondrial 12S ribosomal RNA gene. Based on the sequences, R. rugosa frogs were divided into four groups from Japan and one from South Korea. The ZZ/ZW type is reportedly derived from the XX/XY type, although recently a new ZZ/ZW type of R. rugosa was reported. However, it still remains unclear from where the sex chromosomes in the five groups of this species were derived. In this study, we successfully isolated a sex-linked DNA maker and used it to classify R. rugosa frogs into several groupings. From the DNA marker as well as from nucleotide analysis of the promoter region of the androgen receptor (AR) gene, we identified another female heterogametic group, designated, West-Central. The sex chromosomes in the West-Central originated from the West and Central groups. The results indicate that a sex-linked DNA marker is a verifiable tool to determine the origin of the sex chromosomes in R. rugosa frogs in which the sex-determining system has changed, during two independent events, from the male to female heterogamety.

    DOI PubMed

    Scopus

    9
    Citation
    (Scopus)
  • Participation of androgen and its receptor in sex determination of an amphibian species

    Akira Oike, Maho Kodama, Shigeki Yasumasu, Takashi Yamamoto, Yoriko Nakamura, Etsuro Ito, Masahisa Nakamura

    PLOS ONE   12 ( 6 ) e0178067  2017.06  [Refereed]

     View Summary

    Introduction
    In the Japanese frog Rana (R.) rugosa the androgen receptor (AR) gene on theWchromosome (W-AR) is barely expressed. Previously we showed that incomplete female-to-male sex-reversal occurred in Z-AR transgenic female frogs. To date, however, there is no report showing that AR with androgens can determine genetically programed male sex fate in any vertebrate species. Here, we examined whether AR together with androgens functions as a sex determinant in an amphibian species.
    Methods
    To examine whether complete female-to-male sex-reversal occurs in R. rugosa frogs, we produced AR-transgenic (Tg) and -knockdown (KD) female R. rugosa frogs by the I-SceI meganuclease-mediated gene trap and CRISPR/Cas9 system, respectively. AR-Tg and -KD tadpoles were reared in water containing testosterone (T) at 0 to 7.1 ng/ml. Frozen sections were prepared from the gonads of metamorphosed frogs and immunostained for laminin, Vasa, Pat1a, CYP17 and AR. We also employed PCR analysis to examine Dmrt1, Pat1a and CYP17 expression in the gonads of KD and placebo-KD female frogs.
    Results
    Complete female-to-male sex-reversal occurred in the AR-Tg ZW female frogs when a low dosage of T was supplied in the rearing water of tadpoles. However, no sex-reversal was observed in AR-KD ZW female frogs when the gonads were treated with dosages of T high enough to induce complete female-to-male sex-reversal even in wild type frogs.
    Discussion
    These results suggest that AR with its androgen ligand functions as a male sex-determinant in the ZW type R. rugosa frogs.

    DOI PubMed

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    12
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  • Weak involvement of octopamine in aversive taste learning in a snail

    Hitoshi Aonuma, Mugiho Kaneda, Dai Hatakeyama, Takayuki Watanabe, Ken Lukowiak, Etsuro Ito

    NEUROBIOLOGY OF LEARNING AND MEMORY   141   189 - 198  2017.05  [Refereed]

     View Summary

    The pond snail Lymnaea stagnalis is capable of learning taste aversion by pairing presentations of a sucrose solution and an electric shock and consolidating it into long-term memory (LTM), which is referred to as conditioned taste aversion (CTA). We asked here if the neurotransmitter octopamine is involved in CTA. We first determined the levels of octopamine and its catabolites in the central nervous system (CNS) of snails with varying degrees of food deprivation, because CIA grades are correlated with degrees of food deprivation. We next manipulated the octopamine signaling using both an agonist and an antagonist of octopamine receptors and correlated their respective effects with CTA grades. We found that snails with the least amount of food-deprivation obtained the best CTA grade and had low levels of octopamine; whereas the most severely food-deprived snails did not form CTA and had the highest CNS octopamine levels. In modestly food-deprived snails, octopamine application increased the basal level of feeding response to a sucrose solution, and it did not obstruct CTA formation. Application of phentolamine, an octopamine receptor antagonist, to the most severely food-deprived snails decreased the basal level of feeding elicited by sucrose, but it did not enhance CTA formation. We conclude that octopamine involvement in OA formation in Lymnaea is at best weak, and that the changes in CNS octopamine content are an epiphenomenon. (C) 2017 Elsevier Inc. All rights reserved.

    DOI PubMed

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    11
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  • Cerebral Giant Cells Are Necessary for the Formation and Recall of Memory of Conditioned Taste Aversion in Lymnaea

    Hiroshi Sunada, Ken Lukowiak, Etsuro Ito

    ZOOLOGICAL SCIENCE   34 ( 1 ) 72 - 80  2017.02  [Refereed]

     View Summary

    The pond snail Lymnaea stagnalis can acquire conditioned taste aversion (CTA) as a long-term memory. CTA is caused by the temporal pairing of a stimulus, such as sucrose (the conditioned stimulus; CS), with another stimulus, such as electric shock (the unconditioned stimulus; US). Previous studies have demonstrated changes in both cellular and molecular properties in a pair of neurons known as the cerebral giant cells (CGCs), suggesting that these neurons play a key role in CTA. Here we examined the necessity of the pair of CGC somata for the learning, memory formation and memory recall of CTA by using the soma ablation technique. There was no difference in the feeding response elicited by the CS before and after ablation of the CGC somata. Ablation of the CGC somata before taste-aversion training resulted in the learning acquisition, but the memory formation was not observed 24 h later. We next asked whether memory was present when the CGC somata were ablated 24 h after taste-aversion training. The memory was present before performing the somata ablation. However, when we tested snails five days after somata ablation, the memory recall was not present. Together the data show that: 1) the somata of the CGCs are not necessary for learning acquisition; 2) the somata are necessary for memory formation; and 3) the somata are necessary for memory recall. That is, these results demonstrate that the CGCs function in the long-term memory of CTA in Lymnaea.

    DOI PubMed

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    14
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  • Two Strains of Lymnaea stagnalis and the Progeny from Their Mating Display Differential Memory-Forming Ability on Associative Learning Tasks.

    Hiroshi Sunada, Yuki Totani, Ryota Nakamura, Manabu Sakakibara, Ken Lukowiak, Etsuro Ito

    Frontiers in behavioral neuroscience   11   161 - 161  2017  [Refereed]  [International journal]

     View Summary

    The pond snail Lymnaea stagnalis learns and forms long-term memory (LTM) following both operant conditioning of aerial respiratory behavior and classical conditioning of taste aversive behavior. In the present study, we examined whether there are interstrain differences in the ability to form LTM following these two types of conditioning. A strain of Lymnaea (TC1) collected in Alberta, Canada exhibits superior memory-forming ability following aerial respiratory operant conditioning compared to a laboratory-reared strain of Lymnaea from Netherlands known as the Dutch strain. We asked whether the offspring of the Canadian TC1 and Dutch snails (i.e., filial 1 (F1) cross snails) would have the superior memory ability and found, rather, that their memory ability was average like the Dutch snails. That is, the Canadian TC1 snails have superior ability for LTM formation following aerial respiratory operant conditioning, but the Dutch and the generated F1 cross have average ability for memory forming. We next examined the Canadian TC1, Dutch and F1 cross snails for their ability to learn and form memory following conditioned taste aversion (CTA). All three populations showed similar associative CTA responses. However, both LTM formation and the ratio of good-to-poor performers in the memory retention test were much better in the Dutch snails than the Canadian TC1 and F1 cross snails. The memory abilities of the Canadian TC1 and F1 cross snails were average. Our present findings, therefore, suggest that snails of different strains have different memory abilities, and the F1 cross snails do not inherit the memory ability from the smart strain. To our knowledge, there have been a limited number of studies examining differences in memory ability among invertebrate strains, with the exception of studies using mutant flies.

    DOI PubMed

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    13
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  • Relationship between the grades of a learned aversive-feeding response and the dopamine contents in Lymnaea

    Hitoshi Aonuma, Mugiho Kaneda, Dai Hatakeyama, Takayuki Watanabe, Ken Lukowiak, Etsuro Ito

    BIOLOGY OPEN   5 ( 12 ) 1869 - 1873  2016.12  [Refereed]

     View Summary

    The pond snail Lymnaea learns conditioned taste aversion (CTA) and remembers not to respond to food substances that initially cause a feeding response. The possible relationship between how well snails learn to follow taste-aversion training and brain dopamine contents is not known. We examined this relationship and found the following: first, snails in the act of eating just before the commencement of CTA training were poor learners and had the highest dopamine contents in the brain; second, snails which had an ad libitum access to food, but were not eating just before training, were average learners and had lower dopamine contents; third, snails food-deprived for one day before training were the best learners and had significantly lower contents of dopamine compared to the previous two cohorts. There was a negative correlation between the CTA grades and the brain dopamine contents in these three cohorts. Fourth, snails food-deprived for five days before training were poor learners and had higher dopamine contents. Thus, severe hunger increased the dopamine content in the brain. Because dopamine functions as a reward transmitter, CTA in the severely deprived snails (i.e. the fourth cohort) was thought to be mitigated by a high dopamine content.

    DOI PubMed

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    15
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  • Oxidative Stress Measurement and Prediction of Epileptic Seizure in Children and Adults With Severe Motor and Intellectual Disabilities.

    Morimoto M, Satomura S, Hashimoto T, Ito E, Kyotani S

    Journal of clinical medicine research   8 ( 6 ) 437 - 444  2016.06  [Refereed]

    DOI PubMed

  • An automated learning apparatus for classical conditioning of Lymnaea stagnalis

    Satoshi Takigami, Hiroshi Sunada, Ken Lukowiak, Etsuro Ito, Manabu Sakakibara

    JOURNAL OF NEUROSCIENCE METHODS   259   115 - 121  2016.02  [Refereed]

     View Summary

    Background: The pond snail Lymnaea stagnalis is capable of taste avoidance classical conditioning (TAC) with sucrose as the conditional stimulus (CS) and mechanical prodding as the unconditional stimulus (US). After successful training, feeding behavior is significantly suppressed in response to CS presentation.
    New method: An automated apparatus is described for the training of multiple snails up to 10 snails at the same time. The new apparatus employs an electrical shock obtained from a 9-V dry cell to deliver a consistent and effective current amplitude of 0.4 mu A (i.e., the US).
    Results: Using this apparatus, 10 snails can be conditioned simultaneously. We found that the optimal parameters to result in both short (STM) and long-term memory (LTM) were 15 paired presentations of the CS and US with a 5-min inter-trial interval (ITI) and 0.2-s current duration. However, both STM and LTM were observed with other ITIs tested. Successful TAC with only a single pairing of the CS US occurred with a CS of 100 mM sucrose solution for 60 s followed by a US of 9 V with 0.4 mu A for 5 s.
    Comparison with existing method: The use of automated training apparatus for TAC will enable us to better examine the relationship between strength of CS and US. (C) 2015 Elsevier B.V. All rights reserved.

    DOI PubMed

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    7
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  • Ultrasensitive detection of proteins and sugars at single-cell level

    Satoshi Watabe, Mika Morikawa, Mugiho Kaneda, Kazunari Nakaishi, Akira Nakatsuma, Masaki Ninomiya, Teruki Yoshimura, Toshiaki Miura, Etsuro Ito

    Communicative and Integrative Biology   9 ( 1 ) e1124201  2016  [Refereed]

     View Summary

    Each cell produces its own responses even if it appears identical to other cells. To analyze these individual cell characteristics, we need to measure trace amounts of molecules in a single cell. Nucleic acids in a single cell can be easily amplified by polymerase chain reaction, but single-cell measurement of proteins and sugars will require de novo techniques. In the present study, we outline the techniques we have developed toward this end. For proteins, our ultrasensitive enzymelinked immunosorbent assay (ELISA) coupled with thionicotinamide-adenine dinucleotide cycling can detect proteins at subattomoles per assay. For sugars, fluorescence correlation spectroscopy coupled with glucose oxidase-catalyzed reaction allows us to measure glucose at tens of nM. Our methods thus offer versatile techniques for single-cell-level analyses, and they are hoped to strongly promote single-cell biology as well as to develop noninvasive tests in clinical medicine.

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    14
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  • Immunoreactive insulin in diabetes mellitus patient sera detected by ultrasensitive ELISA with thio-NAD cycling

    Etsuro Ito, Mugiho Kaneda, Hiromi Kodama, Mika Morikawa, Momoko Tai, Kana Aoki, Satoshi Watabe, Kazunari Nakaishi, Seiichi Hashida, Satoshi Tada, Noriyuki Kuroda, Hitomi Imachi, Koji Murao, Masakane Yamashita, Teruki Yoshimura, Toshiaki Miura

    BIOTECHNIQUES   59 ( 6 ) 359 - 367  2015.12  [Refereed]

     View Summary

    To minimize patient suffering, the smallest possible volume of blood should be collected for diagnosis and disease monitoring. When estimating insulin secretion capacity and resistance to insulin in diabetes mellitus (DM), increasing insulin assay immunosensitivity would reduce the blood sample volume required for testing. Here we present an ultrasensitive ELISA coupled with thio-NAD cycling to measure immunoreactive insulin in blood serum. Only 5 mL of serum was required for testing, with a limit of detection (LOD) for the assay of 10-16 moles/assay. Additional recovery tests confirmed this method can detect insulin in sera. Comparisons between a commercially available immunoreactive insulin kit and our ultrasensitive ELISA using the same commercially available reference demonstrated good data correlation, providing further evidence of assay accuracy. Together, these results demonstrate our ultrasensitive ELISA could be a powerful tool in the diagnosis and treatment of not only DM but also many other diseases in the future.

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  • Function of insulin in snail brain in associative learning

    S. Kojima, H. Sunada, K. Mita, M. Sakakibara, K. Lukowiak, E. Ito

    Journal of Comparative Physiology A: Neuroethology, Sensory, Neural, and Behavioral Physiology   201 ( 10 ) 969 - 981  2015.10  [Refereed]

     View Summary

    Insulin is well known as a hormone regulating glucose homeostasis across phyla. Although there are insulin-independent mechanisms for glucose uptake in the mammalian brain, which had contributed to a perception of the brain as an insulin-insensitive organ for decades, the finding of insulin and its receptors in the brain revolutionized the concept of insulin signaling in the brain. However, insulin’s role in brain functions, such as cognition, attention, and memory, remains unknown. Studies using invertebrates with their open blood-vascular system have the promise of promoting a better understanding of the role played by insulin in mediating/modulating cognitive functions. In this review, the relationship between insulin and its impact on long-term memory (LTM) is discussed particularly in snails. The pond snail Lymnaea stagnalis has the ability to undergo conditioned taste aversion (CTA), that is, it associatively learns and forms LTM not to respond with a feeding response to a food that normally elicits a robust feeding response. We show that molluscan insulin-related peptides are up-regulated in snails exhibiting CTA–LTM and play a key role in the causal neural basis of CTA–LTM. We also survey the relevant literature of the roles played by insulin in learning and memory in other phyla.

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    24
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  • Memory block: a consequence of conflict resolution

    Etsuro Ito, Miki Yamagishi, Dai Hatakeyama, Takayuki Watanabe, Yutaka Fujito, Varvara Dyakonova, Ken Lukowiak

    JOURNAL OF EXPERIMENTAL BIOLOGY   218 ( 11 ) 1699 - 1704  2015.06  [Refereed]

     View Summary

    Food deprivation for 1 day in the pond snail Lymnaea stagnalis before aversive classical conditioning results in optimal conditioned taste aversion (CTA) and long-term memory (LTM) formation, whereas 5-day food deprivation before training does not. We hypothesize that snails do in fact learn and form LTM when trained after prolonged food deprivation, but that severe food deprivation blocks their ability to express memory. We trained 5-day food-deprived snails under various conditions, and found that memory was indeed formed but is overpowered by severe food deprivation. Moreover, CTA-LTM was context dependent and was observed only when the snails were in a context similar to that in which the training occurred.

    DOI PubMed

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    24
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  • Detection of HIV-1 p24 at Attomole Level by Ultrasensitive ELISA with Thio-NAD Cycling

    Akira Nakatsuma, Mugiho Kaneda, Hiromi Kodama, Mika Morikawa, Satoshi Watabe, Kazunari Nakaishi, Masakane Yamashita, Teruki Yoshimura, Toshiaki Miura, Masaki Ninomiya, Etsuro Ito

    PLOS ONE   10 ( 6 ) e0131319  2015.06  [Refereed]

     View Summary

    To reduce the window period between HIV-1 infection and the ability to diagnose it, a fourth-generation immunoassay including the detection of HIV-1 p24 antigen has been developed. However, because the commercially available systems for this assay use special, high-cost instruments to measure, for example, chemiluminescence, it is performed only by diagnostics companies and hub hospitals. To overcome this limitation, we applied an ultrasensitive ELISA coupled with a thio-NAD cycling, which is based on a usual enzyme immunoassay without special instruments, to detect HIV-1 p24. The p24 detection limit by our ultrasensitive ELISA was 0.0065 IU/assay (i.e., ca. 10(-18) moles/assay). Because HIV-1 p24 antigen is thought to be present in the virion in much greater numbers than viral RNA copies, the value of 10(-18) moles of the p24/assay corresponds to ca. 10(3) copies of the HIV-1 RNA/assay. That is, our ultrasensitive ELISA is chasing the detection limit (10(2) copies/assay) obtained by PCR-based nucleic acid testing (NAT) with a margin of only one different order. Further, the detection limit by our ultrasensitive ELISA is less than that mandated for a CE-marked HIV antigen/antibody assay. An additional recovery test using blood supported the reliability of our ultrasensitive ELISA.

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    20
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  • The activity of isolated neurons and the modulatory state of an isolated nervous system represent a recent behavioural state

    Varvara E. Dyakonova, Laszlo Hernadi, Etsuro Ito, Taisia L. Dyakonova, Ilya A. Chistopolsky, Igor S. Zakharov, Dmitri A. Sakharov

    JOURNAL OF EXPERIMENTAL BIOLOGY   218 ( 8 ) 1151 - 1158  2015.04  [Refereed]

     View Summary

    Behavioural/motivational state is known to influence nearly all aspects of physiology and behaviour. The cellular basis of behavioural state control is only partially understood. Our investigation, performed on the pond snail Lymnaea stagnalis whose nervous system is useful for work on completely isolated neurons, provided several results related to this problem. First, we demonstrated that the behavioural state can produce long-term changes in individual neurons that persist even after neuron isolation from the nervous system. Specifically, we found that pedal serotonergic neurons that control locomotion show higher activity and lower membrane potential after being isolated from the nervous systems of hungry animals. Second, we showed that the modulatory state (the chemical neuroactive microenvironment of the central ganglia) changes in accordance with the nutritional state of an animal and produces predicted changes in single isolated locomotor neurons. Third, we report that observed hunger-induced effects can be explained by the increased synthesis of serotonin in pedal serotonergic neurons, which has an impact on the electrical activity of isolated serotonergic neurons and the intensity of extrasynaptic serotonin release from the pedal ganglia.

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    17
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  • The Yerkes-Dodson law and appropriate stimuli for conditioned taste aversion in Lymnaea

    Etsuro Ito, Miki Yamagishi, Satoshi Takigami, Manabu Sakakibara, Yutaka Fujito, Ken Lukowiak

    JOURNAL OF EXPERIMENTAL BIOLOGY   218 ( 3 ) 336 - 339  2015.02  [Refereed]

     View Summary

    The pond snail Lymnaea stagnalis can learn conditioned taste aversion and then consolidate it into long-term memory (LTM). A high-voltage electric shock was used as the unconditioned stimulus, where we have previously used KCl. We varied the strength of both the conditioned and unconditioned stimuli to determine whether the so-called Yerkes-Dodson law prevailed. This is an empirical relationship between the state of arousal and LTM formation, showing that there is an optimal level of arousal leading to memory formation. However, too little or too much arousal results in poorer LTM. We found here that the most appropriate stimuli to use in taste aversion training in Lymnaea were a 10 mmol l(-1) sucrose solution as the conditioned stimulus and a 3 s electric shock as the unconditioned stimulus.

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    25
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  • Effects of serotonin on the heartbeat of pond snails in a hunger state

    Miki Yamagishi, Takayuki Watanabe, Dai Hatakeyama, Etsuro Ito

    Biophysics (Japan)   11   1 - 5  2015  [Refereed]

     View Summary

    Serotonin (5-hydroxytryptamine: 5-HT) is a multimodal transmitter that controls both feeding response and heartbeat in snails. However, the effects of 5-HT on the hunger state are still unknown. We therefore examined the relation among the hunger state, the heartbeat rate and the 5-HT action in food-starved snails. We found that the hunger state was significantly distinguished by the heartbeat rate in snails. The heartbeat rate was high in the food-satiated snails, whereas it was low in the food-starved snails. An increase in 5-HT concentration in the body boosted the heartbeat rate in the food-starved snails, but did not affect the rate in the food-satiated snails. These results suggest that 5-HT application may mimic the change from a starvation to a satiation state normally achieved by direct ingestion of food.

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    11
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  • Preface of Special Issue "TRP channels: their functional roles in medical sciences".

    Ito E

    Biophysics (Nagoya-shi, Japan)   11   7 - 8  2015  [Refereed]

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  • Thermodynamic implications of high Q10 of thermo-TRP channels in living cells

    Etsuro Ito, Yusuke Ikemoto, Tohru Yoshioka

    Biophysics (Japan)   11   33 - 38  2015  [Refereed]

     View Summary

    The activity of thermo-transient receptor potential (TRP) channels is highly dependent on temperature, and thus thermo-TRP reactions have a high temperature coefficient Q10. In thermodynamics, a high value of Q10 indicates the existence of a large activation energy (i.e., a large enthalpy) over a short period during the transition process between the closed and open states of the channels. The Gibbs free energy equation shows that a large entropy is required to compensate for this large enthalpy and permit activation of the channels, suggesting a large conformational change of the channels. These large values of enthalpy and entropy seem to be a match for the values of the unfolding process of globular proteins. We outline these thermodynamic issues in thermo-TRPs.

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  • The activity of isolated snail neurons controlling locomotion is affected by glucose

    Varvara Dyakonova, László Hernádi, Etsuro Ito, Taisia Dyakonova, Igor Zakharov, Dmitri Sakharov

    Biophysics (Japan)   11   55 - 60  2015  [Refereed]

     View Summary

    The involvement of serotonin in mediating hunger-related changes in behavioral state has been described in many invertebrates. However, the mechanisms by which hunger signals to serotonergic cells remain unknown. We tested the hypothesis that serotonergic neurons can directly sense the concentration of glucose, a metabolic indicator of nutritional state. In the snail Lymnaea stagnalis, we demonstrate that completely isolated pedal serotonergic neurons that control locomotion changed their biophysical characteristics in response to glucose application by lowering membrane potential and decreasing the firing rate. Additionally, the excitatory response of the isolated serotonergic neurons to the neuroactive microenvironment of the pedal ganglia was significantly lowered by glucose application. Because hunger has been reported to increase the activity of select neurons and their responses to the pedal ganglia microenvironment, these responses to glucose are in accordance with the hypothesis that direct glucose signaling is involved in the mediation of the hunger-related behavioral state.

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    15
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  • Subattomole detection of adiponectin in urine by ultrasensitive ELISA coupled with thio-NAD cycling.

    Morikawa M, Naito R, Mita K, Watabe S, Nakaishi K, Yoshimura T, Miura T, Hashida S, Ito E

    Biophysics and physicobiology   12   79 - 86  2015  [Refereed]

     View Summary

    Adiponectin is a hormone secreted from adipocytes, and it demonstrates antidiabetic, anti-atherosclerotic, anti-obesity and anti-inflammatory effects. However, the patterns of change in urinary adiponectin levels in various diseases remain unknown, because only trace amounts of the hormone are present in urine. In the present study, we applied an ultrasensitive ELISA coupled with thio-NAD cycling to measure urinary adiponectin levels. Spike-and-recovery tests using urine confirmed the reliability of our ultrasensitive ELISA. The limit of detection for adiponectin in urine was 2.3×10–19 moles/assay (1.4 pg/mL). The urinary adiponectin concentration ranged between 0.04 and 5.82 ng/mL in healthy subjects. The pilot study showed that the urinary adiponectin levels, which were corrected by the creatinine concentration, were 0.73±0.50 (ng/mg creatinine, N=6) for healthy subjects, versus 12.02±3.85 (ng/mg creatinine, N=3) for patients with diabetes mellitus (DM). That is, the urinary adiponectin levels were higher (P<0.05) in DM patients than in healthy subjects. Further, these urinary adiponectin levels tended to increase with the progression of DM accompanied with nephropathy. Our method is thus expected to provide a simple, rapid and reasonably priced test for noninvasive monitoring of the progression of DM without the requirement of special tools.

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    15
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  • An increase in insulin is important for the acquisition conditioned taste aversion in Lymnaea

    Koichi Mita, Miki Yamagishi, Yutaka Fujito, Ken Lukowiak, Etsuro Ito

    NEUROBIOLOGY OF LEARNING AND MEMORY   116   132 - 138  2014.12  [Refereed]

     View Summary

    Conditioned taste aversion (CTA) in Lymnaea is brought about by pairing a sucrose solution (the conditioned stimulus, CS) with an electric shock (the unconditioned stimulus, US). Following repeated CS-US pairings, CTA occurs and it is consolidated into long-term memory (LTM). The best CTA is achieved, if snails are food-deprived for I day before training commences. With a longer period of food deprivation (5 days), learning and memory formation does not occur. It has been hypothesized that the levels of insulin in the central nervous system (CNS) are very important for CTA to occur. To test his hypothesis, we injected insulin directly into 5-day food-deprived snails. The injection of insulin, as expected, resulted in a decrease in hemolymph glucose concentration. Consistent with our hypothesis with insulin injection, learning and memory formation of CTA occurred. That is, the 'insulin spike' is more important than an increase in hemolymph glucose concentration for CTA-LTM. If we injected an insulin receptor antibody into the snails before the insulin injection, learning was formed but memory formation was not, which is consistent with our previous study. Therefore, a rise in the insulin concentration (i.e., insulin spike) in the CNS is considered to be a key determining factor in the process of CTA-LTM. (C) 2014 Elsevier Inc. All rights reserved.

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    22
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  • The cholinergic system in the olfactory center of the terrestrial slug Limax

    Ryota Matsuo, Suguru Kobayashi, Kyoko Wakiya, Miki Yamagishi, Masayuki Fukuoka, Etsuro Ito

    Journal of Comparative Neurology   522 ( 13 ) 2951 - 2966  2014.09  [Refereed]

     View Summary

    Acetylcholine plays various important roles in the central nervous system of invertebrates as well as vertebrates. In the olfactory center of the terrestrial slug Limax, the local field potential (LFP) oscillates, and the change in its oscillatory frequency is thought to correlate with the detection of odor that potentially changes an ongoing behavior of the animal. Acetylcholine is known to upregulate the frequency of the LFP oscillation, and is one of the candidates for the neurotransmitters that are involved in such higher cognitive functions. However, there have been no histological data on the cholinergic system in gastropods, nor are there data on the receptors that are responsible for the upregulation of the oscillatory frequency of LFP due to the lack of analytical tools (such as antibodies or cDNA sequence information on cholinergic system-related genes). Here we cloned the cDNAs of choline acetyltransferase (ChAT), acetylcholinesterase, vesicular acetylcholine transporter, and several nicotinic acetylcholine receptors (nAChRs), and investigated their localization in the brain of Limax. We also generated a polyclonal antibody against ChAT to examine its localization, and investigated pharmacologically the involvement of nAChRs in the LFP oscillation. Our data showed: 1) dense distribution of the neurons expressing mRNAs of ChAT and vesicular acetylcholine transporter in the olfactory center
    2) spatially unique expression patterns of different nAChRs in the olfactory center
    3) involvement of nAChRs in the upregulation of the oscillation
    4) localization of ChAT protein in nerve fibers and/or terminals
    and 5) the presence of cholinergic nerves in the tentacles. © 2014 Wiley Periodicals, Inc.

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    11
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  • Error in the Honeybee Waggle Dance Improves Foraging Flexibility

    Ryuichi Okada, Hidetoshi Ikeno, Toshifumi Kimura, Mizue Ohashi, Hitoshi Aonuma, Etsuro Ito

    SCIENTIFIC REPORTS   4   4175  2014.02  [Refereed]

     View Summary

    The honeybee waggle dance communicates the location of profitable food sources, usually with a certain degree of error in the directional information ranging from 10-15 degrees at the lower margin. We simulated one-day colonial foraging to address the biological significance of information error in the waggle dance. When the error was 30 degrees or larger, the waggle dance was not beneficial. If the error was 15 degrees, the waggle dance was beneficial when the food sources were scarce. When the error was 10 degrees or smaller, the waggle dance was beneficial under all the conditions tested. Our simulation also showed that precise information (0-5 degrees error) yielded great success in finding feeders, but also caused failures at finding new feeders, i.e., a high-risk high-return strategy. The observation that actual bees perform the waggle dance with an error of 10-15 degrees might reflect, at least in part, the maintenance of a successful yet risky foraging trade-off.

    DOI PubMed

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    7
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  • What are the elements of motivation for acquisition of conditioned taste aversion?

    Koichi Mita, Akiko Okuta, Ryuichi Okada, Dai Hatakeyama, Emi Otsuka, Miki Yamagishi, Mika Morikawa, Yuki Naganuma, Yutaka Fujito, Varvara Dyakonova, Ken Lukowiak, Etsuro Ito

    NEUROBIOLOGY OF LEARNING AND MEMORY   107   1 - 12  2014.01  [Refereed]

     View Summary

    The pond snail Lymnaea stagnalis is capable of being classically conditioned to avoid food and to consolidate this aversion into a long-term memory (LTM). Previous studies have shown that the length of food deprivation is important for both the acquisition of taste aversion and its consolidation into LTM, which is referred to as conditioned taste aversion (CTA). Here we tested the hypothesis that the hemolymph glucose concentration is an important factor in the learning and memory of CTA. One-day food deprivation resulted in the best learning and memory, whereas more prolonged food deprivation had diminishing effects. Five-day food deprivation resulted in snails incapable of learning or remembering. During this food deprivation period, the hemolymph glucose concentration decreased. If snails were fed for 2 days following the 5-day food deprivation, their glucose levels increased significantly and they exhibited both learning and memory, but neither learning nor memory was as good as with the 1-day food-deprived snails. Injection of the snails with insulin to reduce glucose levels resulted in better learning and memory. Insulin is also known to cause a long-term enhancement of synaptic transmission between the feeding-related neurons. On the other hand, injection of glucose into 5-day food-deprived snails did not alter their inability to learn and remember. However, if these snails were fed on sucrose for 3 min, they then exhibited learning and memory formation. Our data suggest that hemolymph glucose concentration is an important factor in motivating acquisition of CTA in Lymnaea and that the action of insulin in the brain and the feeding behavior are also important factors. (C) 2013 Elsevier Inc. All rights reserved.

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    24
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  • Ultrasensitive enzyme-linked immunosorbent assay (ELISA) of proteins by combination with the thio-NAD cycling method

    Satoshi Watabe, Hiromi Kodama, Mugiho Kaneda, Mika Morikawa, Kazunari Nakaishi, Teruki Yoshimura, Atsushi Iwai, Toshiaki Miura, Etsuro Ito

    Biophysics (Japan)   10   49 - 54  2014  [Refereed]

     View Summary

    An ultrasensitive method for the determination of proteins is described that combines an enzyme-linked immunosorbent assay (ELISA) and a thionicotinamide-adenine dinucleotide (thio-NAD) cycling method. A sandwich method using a primary and a secondary antibody for antigens is employed in an ELISA. An androsterone derivative, 3α-hydroxysteroid, is produced by the hydrolysis of 3α-hydroxysteroid 3-phosphate with alkaline phosphatase linked to the secondary antibody. This 3α-hydroxysteroid is oxidized to a 3-ketosteroid by 3α-hydroxysteroid dehydrogenase (3α-HSD) with a cofactor thio-NAD. By the opposite reaction, the 3-ketosteroid is reduced to a 3α-hydroxysteroid by 3α-HSD with a cofactor NADH. During this cycling reaction, thio-NADH accumulates in a quadratic function-like fashion. Accumulated thio-NADH can be measured directly at an absorbance of 400 nm without any interference from other cofactors. These features enable us to detect a target protein with ultrasensitivity (10–19 mol/assay) by measuring the cumulative quantity of thio-NADH. Our ultrasensitive determination of proteins thus allows for the detection of small amounts of proteins only by the application of thio-NAD cycling reagents to the usual ELISA system.

    DOI PubMed

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    27
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  • Target innervation is necessary for neuronal polyploidization in the terrestrial slug Limax

    Ryota Matsuo, Miki Yamagishi, Kyoko Wakiya, Yoko Tanaka, Etsuro Ito

    DEVELOPMENTAL NEUROBIOLOGY   73 ( 8 ) 609 - 620  2013.08  [Refereed]

     View Summary

    The brain of gastropod mollusks contains many giant neurons with polyploid genomic DNAs. Such DNAs are generated through repeated DNA endoreplication during body growth. However, it is not known what triggers DNA endoreplication in neurons. There are two possibilities: (1) DNAs are replicated in response to some unknown molecules in the hemolymph that reflect the nutritive status of the animal; or (2) DNAs are replicated in response to some unknown factors that are retrogradely transported through axons from the innervated target organs. We first tested whether hemolymph with rich nutrition could induce DNA endoreplication. We tested whether the transplanted brain exhibits enhanced DNA endoreplication like an endogenous brain does when transplanted into the homocoel of the body of a slug whose body growth is promoted by an increased food supply. However, no enhancement was observed in the frequency of DNA endoreplication when we compared the transplanted brains in the growth-promoted and growth-suppressed host slugs, suggesting that the humoral environment is irrelevant to triggering the body growth-dependent DNA endoreplication. Next, we tested the requirement of target innervation by surgically dissecting a unilateral posterior pedal nerve of an endogenous brain. Substantially lower number of neurons exhibited DNA endoreplication in the pedal ganglion ipsilateral to the dissected nerve. These results support the view that enhanced DNA endoreplication is mediated by target innervation and is not brought about through the direct effect of humoral factors in the hemolymph during body growth. (c) 2013 Wiley Periodicals, Inc. Develop Neurobiol 73: 609-620, 2013

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    10
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  • From likes to dislikes: conditioned taste aversion in the great pond snail (Lymnaea stagnalis)

    E. Ito, S. Kojima, K. Lukowiak, M. Sakakibara

    CANADIAN JOURNAL OF ZOOLOGY   91 ( 6 ) 405 - 412  2013.06  [Refereed]  [Invited]

     View Summary

    The neural circuitry comprising the central pattern generator (CPG) that drives feeding behavior in the great pond snail (Lymnaea stagnalis (L., 1758)) has been worked out. Because the feeding behavior undergoes associative learning and long-term memory (LTM) formation, it provides an excellent opportunity to study the causal neuronal mechanisms of these two processes. In this review, we explore some of the possible causal neuronal mechanisms of associative learning of conditioned taste aversion (CTA) and its subsequent consolidation processes into LTM in L. stagnalis. In the CTA training procedure, a sucrose solution, which evokes a feeding response, is used as the conditioned stimulus (CS) and a potassium chloride solution, which causes a withdrawal response, is used as the unconditioned stimulus (US). The pairing of the CS-US alters both the feeding response of the snail and the function of a pair of higher order interneurons in the cerebral ganglia. Following the acquisition of CTA, the polysynaptic inhibitory synaptic input from the higher order interneurons onto the feeding CPG neurons is enhanced, resulting in suppression of the feeding response. These changes in synaptic efficacy are thought to constitute a "memory trace" for CTA in L. stagnalis.

    DOI

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    34
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  • Consolidation of long-term memory by insulin in Lymnaea is not brought about by changing the number of insulin receptors

    Dai Hatakeyama, Akiko Okuta, Emi Otsuka, Ken Lukowiak, Etsuro Ito

    Communicative and Integrative Biology   6 ( 3 ) e23955  2013.05  [Refereed]

     View Summary

    The pond snail Lymnaea stagnalis learns taste aversion and consolidates it into long-term memory (LTM). This is referred to as conditioned taste aversion (CTA). The superfusion of molluscan insulin-related peptides (MIPs) over the isolated snail brain causes a long-term enhancement of synaptic input between the cerebral giant cell and the B1 buccal motor neuron. This enhancement is hypothesized to underlie CTA. The synaptic enhancement caused by the superfusion of MIPs can be blocked by the application of human insulin receptor antibody, which recognizes the extracellular domain of human insulin receptor and acts as an antagonist even for MIP receptors. An injection of the human insulin receptor antibody into the abdominal cavity of trained snails blocks the consolidation process leading to LTM, even though the snails acquire taste aversion. Here, we examined whether or not taste-aversion training changes the mRNA expression level of MIP receptor in the snail brain and found that it does not. This result, taken together with previous findings, suggest that the MIPs' effect on synaptic function in the snail brain is attributable to a change in the MIP concentration, and not to a change in the mRNA expression level of MIP receptor, which is thought to reflect the number of MIP receptors. © 2013 Landes Bioscience.

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    26
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  • Paired pulse ratio analysis of insulin-induced synaptic plasticity in the snail brain

    Jun Murakami, Ryuichi Okada, Yutaka Fujito, Manabu Sakakibara, Ken Lukowiak, Etsuro Ito

    JOURNAL OF EXPERIMENTAL BIOLOGY   216 ( 10 ) 1771 - 1773  2013.05  [Refereed]

     View Summary

    Insulin's action in the brain can directly alter cognitive functioning. We have recently shown that molluscan insulin-related peptides are upregulated following a conditioned taste aversion (CTA) training procedure. In addition, when mammalian insulin is superfused over the isolated Lymnaea stagnalis central nervous system, it elicits long-term synaptic enhancement at the monosynaptic connection between the cerebral giant cell and the buccal 1 (B1) motor neuron. This synaptic enhancement is thought to be a neural correlate of CTA. Here, we examined whether the observed changes in synaptic plasticity were the result of presynaptic and/or postsynaptic alterations using the paired pulse procedure. The paired pulse ratio was unaltered following insulin application, suggesting that insulin's effects on synaptic plasticity are mediated postsynaptically in the B1 motor neuron. Thus, it was suggested that postsynaptic changes need to be considered when insulin's actions on synaptic plasticity are examined.

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    24
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  • Target innervation is necessary for neuronal polyploidization in the terrestrial slug Limax.

    Matsuo R, Yamagishi M, Wakiya K, Tanaka Y, Ito E

    Developmental neurobiology    2013.05  [Refereed]

    DOI PubMed

  • Involvement of nitric oxide in memory formation in microbrains

    Etsuro Ito, Ryota Matsuo, Ryuichi Okada

    NEUROSCIENCE LETTERS   541   1 - 3  2013.04  [Refereed]  [Invited]

    DOI PubMed

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    4
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  • Organization of the procerebrum in terrestrial pulmonates (Helix, Limax) reconsidered: cell mass layer synaptology and its serotonergic input system

    Karoly Elekes, Izabella Battonyai, Suguru Kobayashi, Etsuro Ito

    BRAIN STRUCTURE & FUNCTION   218 ( 2 ) 477 - 490  2013.03  [Refereed]

     View Summary

    The synaptology of the cell body layer of the olfactory center, procerebrum, was investigated in two prominent terrestrial pulmonate gastropod species, Helix pomatia and Limax valentianus. In addition, the analysis of the 5-HT-immunoreactive innervation, including ultrastructural level, was performed at high resolution in H. pomatia. A highly complex system of synaptic and non-synaptic connections was found in the procerebrum of both species connected to local neuropil areas of different size. The procerebral (globuli) cell perikarya were richly innervated by varicosities meanwhile the axon profiles also established contacts with each other. Synaptic configurations including convergence, divergence and presynaptic modulation were also revealed. The frequent occurrence of unspecialized but close axo-somatic and axo-axonic membrane contacts referring to the modulatory forms of transmitter release were also accompanied by membrane configurations indicative of active exocytosis. In H. pomatia, the cell mass layer was shown to receive a rich 5-HT-immunoreactive innervation, forming a dense network around the cell bodies. At ultrastructural level, 5-HT-immunoreactive varicosities contacted both cell bodies and different unlabeled axon profiles. Our results suggest that the local neuropil regions in the cell body layer are site of local circuits, which may play a decisive role in olfactory integrative processes bound to the procerebrum. The pattern and form of the 5-HT-immunoreactive innervation of extrinsic origin suggest an overall modulatory role in the cell body layer. The results may serve a basis for considering the role of local intercellular events, connected to microcircuits, within the procerebrum cell body layer involved in oscillation activities.

    DOI

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    12
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  • Spectrophotometric method for the assay of steroid 5α-Reductase activity of rat liver and prostate microsomes

    Atsushi Iwai, Teruki Yoshimura, Keiji Wada, Satoshi Watabe, Yuki Sakamoto, Etsuro Ito, Toshiaki Miura

    Analytical Sciences   29 ( 4 ) 455 - 459  2013  [Refereed]

     View Summary

    A simple spectrophotometric method for the assay of steroid 5α-reductase (5α-sr) was developed in which 5α-dihydrotestosterone (5α-dht) and 5α-androstane-3α,17β-diol (5α-diol), metabolites formed in the nadph-dependent reduction of testosterone with enzyme sources of 5α-sr, were measured by enzymatic cycling using 3α-hydroxysteroid dehydrogenase in the presence of excess thionicotinamide-adenine dinucleotide (thio-nad) and nadh. it was found that 5α-sr activity was proportional to the accumulated thio-nadh having an absorption maximum at 400 nm. because of the high cycling rate (&gt
    600 cycle per min) and no interference from testosterone, enzymatic cycling can determine the sum of 5α-dht and 5α-diol at the picomole level without separation from excess testosterone. the present method was readily applicable to the assay of 5α-sr activity of rat liver and prostate microsomes as well as to the assay of inhibitory activity of finasteride, a synthetic inhibitor of 5α-sr. ©2013 The Japan Society for Analytical Chemistry.

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  • Detection of H2O2 by Fluorescence Correlation Spectroscopy

    Etsuro Ito, Satoshi Watabe, Mika Morikawa, Hiromi Kodama, Ryuichi Okada, Toshiaki Miura

    HYDROGEN PEROXIDE AND CELL SIGNALING, PT A   526   135 - 143  2013  [Refereed]  [Invited]

     View Summary

    Fluorescence correlation spectroscopy (FCS) is a technique in which measurement of fluorescence intensity fluctuations is used to clarify dynamic molecular interactions within a very small space in a solution containing a small number of fluorescent molecules. The FCS-based analysis gives the average number and average diffusion time of the fluorescent molecules during their passage through a very small space. One advantage of FCS is that physical separation between free and bound fluorescent probes is not required because the properties of fluorescence fluctuations are accounted for. Therefore, when fluorescent probes are bound with proteins by peroxidase and hydrogen peroxide (H2O2), FCS enables us to detect H2O2 with high sensitivity. In addition, because H2O2 is generated by oxidase-catalyzed reactions, a highly sensitive method for detecting H2O2 is applicable to the measurement of low levels of various oxidases and their substrates, such as glucose. We here describe the protocol of a de novo, highly sensitive method for the measurement of H2O2 and glucose using FCS.

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  • Involvement of Insulin-Like Peptide in Long-Term Synaptic Plasticity and Long-Term Memory of the Pond Snail Lymnaea stagnalis

    Jun Murakami, Ryuichi Okada, Hisayo Sadamoto, Suguru Kobayashi, Koichi Mita, Yuki Sakamoto, Miki Yamagishi, Dai Hatakeyama, Emi Otsuka, Akiko Okuta, Hiroshi Sunada, Satoshi Takigami, Manabu Sakakibara, Yutaka Fujito, Masahiko Awaji, Shunsuke Moriyama, Ken Lukowiak, Etsuro Ito

    JOURNAL OF NEUROSCIENCE   33 ( 1 ) 371 - 383  2013.01  [Refereed]

     View Summary

    The pond snail Lymnaea stagnalis is capable of learning taste aversion and consolidating this learning into long-term memory (LTM) that is called conditioned taste aversion (CTA). Previous studies showed that some molluscan insulin-related peptides (MIPs) were upregulated in snails exhibiting CTA. We thus hypothesized that MIPs play an important role in neurons underlying the CTA-LTM consolidation process. To examine this hypothesis, we first observed the distribution of MIP II, a major peptide of MIPs, and MIP receptor and determined the amounts of their mRNAs in the CNS. MIP II was only observed in the light green cells in the cerebral ganglia, but the MIP receptor was distributed throughout the entire CNS, including the buccal ganglia. Next, when we applied exogenous mammalian insulin, secretions from MIP-containing cells or partially purified MIPs, to the isolated CNS, we observed a long-term change in synaptic efficacy (i.e., enhancement) of the synaptic connection between the cerebral giant cell (a key interneuron for CTA) and the B1 motor neuron (a buccal motor neuron). This synaptic enhancement was blocked by application of an insulin receptor antibody to the isolated CNS. Finally, injection of the insulin receptor antibody into the snail before CTA training, while not blocking the acquisition of taste aversion learning, blocked the memory consolidation process; thus, LTM was not observed. These data suggest that MIPs trigger changes in synaptic connectivity that may be correlated with the consolidation of taste aversion learning into CTA-LTM in the Lymnaea CNS.

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  • Increase in cyclic AMP concentration in a cerebral giant interneuron mimics part of a memory trace for conditioned taste aversion of the pond snail

    Emi Otsuka, Miho Matsunaga, Ryuichi Okada, Miki Yamagishi, Akiko Okuta, Ken Lukowiak, Etsuro Ito

    Biophysics (Japan)   9   161 - 166  2013  [Refereed]

     View Summary

    Conditioned taste aversion (CTA) can be classically conditioned in the pond snail Lymnaea stagnalis and subsequently be consolidated into long-term memory (LTM). The neural trace that subserves CTA-LTM can be summarized as follows: A polysynaptic inhibitory postsyn-aptic potential recorded in the neuron 1 medial (N1M) cell in the conditioned snails as a result of activation of the cerebral giant cell (CGC) is larger and lasts longer than that in control snails. The N1M cell is ultimately activated by the CGC via the neuron 3 tonic (N3t) cell. That is, the inhibitory monosynaptic inputs from the N3t cell to the N1M cell are facilitated. The N1M and N3t cells are the members of feeding central pattern generator, whereas the CGC is a multimodal interneuron thought to play a key role in feeding behavior. Here we examined the involvement of a second messenger, cAMP, in the establishment of the memory trace. We injected cAMP into the CGC and monitored the potentials of the B3 motor neuron activated by the CGC. B3 activity is used as an index for the synaptic inputs from the N3t cell to the N1M cell. We found that the B3 potentials were transiently enlarged. Thus, when the cAMP concentration is increased in the CGC by taste aversion training, cAMP-induced changes may play a key role in the establishment of a memory trace in the N3t cell. © 2013 THE BIOPHYSICAL SOCIETY OF JAPAN.

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  • [Development of super high-sensitive measurement of proteins by combination of ELISA and enzyme cycling methods].

    Ito E, Watabe S

    Rinsho byori. The Japanese journal of clinical pathology   60 ( 11 ) 1088 - 1093  2012.11  [Refereed]

    PubMed CiNii

  • Memory Trace in Feeding Neural Circuitry Underlying Conditioned Taste Aversion in Lymnaea

    Etsuro Ito, Emi Otsuka, Noriyuki Hama, Hitoshi Aonuma, Ryuichi Okada, Dai Hatakeyama, Yutaka Fujito, Suguru Kobayashi

    PLOS ONE   7 ( 8 ) e43151  2012.08  [Refereed]

     View Summary

    Background: The pond snail Lymnaea stagnalis can maintain a conditioned taste aversion (CTA) as a long-term memory. Previous studies have shown that the inhibitory postsynaptic potential (IPSP) evoked in the neuron 1 medial (N1M) cell by activation of the cerebral giant cell (CGC) in taste aversion-trained snails was larger and lasted longer than that in control snails. The N1M cell is one of the interneurons in the feeding central pattern generator (CPG), and the CGC is a key regulatory neuron for the feeding CPG.
    Methodology/Principle Findings: Previous studies have suggested that the neural circuit between the CGC and the N1M cell consists of two synaptic connections: (1) the excitatory connection from the CGC to the neuron 3 tonic (N3t) cell and (2) the inhibitory connection from the N3t cell to the N1M cell. However, because the N3t cell is too small to access consistently by electrophysiological methods, in the present study the synaptic inputs from the CGC to the N3t cell and those from the N3t cell to the N1M cell were monitored as the monosynaptic excitatory postsynaptic potential (EPSP) recorded in the large B1 and B3 motor neurons, respectively. The evoked monosynaptic EPSPs of the B1 motor neurons in the brains isolated from the taste aversion-trained snails were identical to those in the control snails, whereas the spontaneous monosynaptic EPSPs of the B3 motor neurons were significantly enlarged.
    Conclusion/Significance: These results suggest that, after taste aversion training, the monosynaptic inputs from the N3t cell to the following neurons including the N1M cell are specifically facilitated. That is, one of the memory traces for taste aversion remains as an increase in neurotransmitter released from the N3t cell. We thus conclude that the N3t cell suppresses the N1M cell in the feeding CPG, in response to the conditioned stimulus in Lymnaea CTA.

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  • Whole genome amplification in large neurons of the terrestrial slug Limax

    Miki Yamagishi, Etsuro Ito, Ryota Matsuo

    JOURNAL OF NEUROCHEMISTRY   122 ( 4 ) 727 - 737  2012.08  [Refereed]

     View Summary

    J. Neurochem. (2012) 122, 727737. Abstract The brain of gastropod mollusks contains giant neurons whose nuclei are enlarged with a large amount of genomic DNA. Such DNA is produced by repeated endoreplication. We have previously demonstrated that the frequency of the neuronal DNA endoreplication is correlative to the body growth of the adult land slug and to the increase in the amount of transcripts within the neuron. However, it has long been controversial whether the neuronal DNA endoreplication entails whole genome amplification (polyploidy), or whether only the necessary genomic loci are amplified (polyteny, polysomy, or cis-amplification by unequal recombination). In the present study, we adopted two modern techniques quantitative genomic PCR and 5'-bromodeoxyuridine labeling to distinguish between these two possibilities. Our results demonstrated that multiple genomic loci were amplified to the same extent irrespective of the transcriptional activities at these loci. Moreover, the visceral giant cell, the biggest neuron in the slugs brain, was estimated to contain approximately 10 000-times as much genomic DNA as the haploid amount. The 5'-bromodeoxyuridine-labeling experiments also revealed a uniform DNA synthesis within the nucleus. These results strongly support the idea that the giant neurons contain a polyploid genome rather than a locus-specific amplified genome.

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  • Excitatory effects of GABA on procerebrum neurons in a slug

    Suguru Kobayashi, Ryota Matsuo, Hisayo Sadamoto, Satoshi Watanabe, Etsuro Ito

    JOURNAL OF NEUROPHYSIOLOGY   108 ( 4 ) 989 - 998  2012.08  [Refereed]

     View Summary

    Kobayashi S, Matsuo R, Sadamoto H, Watanabe S, Ito E. Excitatory effects of GABA on procerebrum neurons in a slug. J Neurophysiol 108: 989-998, 2012. First published May 9, 2012; doi:10.1152/jn.01137.2010.-Classical neurotransmitters, such as glutamate and gamma-aminobutyric acid (GABA), often have different actions on invertebrate neurons from those reported for vertebrate neurons. In the terrestrial mollusk Limax, glutamate was found to function as an inhibitory transmitter in the procerebrum (PC), but it has not yet been clarified how GABA Acts in the PC. We thus examined what effects GABA exerts on PC neurons in the present study. For this purpose, we first applied GABA to isolated PC preparations and recorded postsynaptic currents and potentials in PC neurons. The GABA Application reduced the amplitude of inhibitory postsynaptic currents and depolarization-induced outward currents recorded in nonbursting neurons and increased the number of spontaneous spikes of nonbursting neurons. However, direct GABA-induced currents were not observed in either bursting or nonbursting neurons. These results suggest a potential direct effect of GABA on outward currents resulting in enhanced excitability of PC neurons. Next, we measured the change in [Ca2+](i) in cultured PC neurons by application of GABA. The GABA Application increased spontaneous Ca2+ events in cultured neurons. These Ca2+ events were ascribable to the influx of extracellular Ca2+. We then confirmed the presence of GABA And GABA receptors in the PC. The GABA-like immunoreactivity was observed in the neuropil layers of the PC, and the mRNAs for both GABA(A) and GABA(B) receptors were expressed in the PC. In particular, GABA(B) receptor mRNA, rather than GABA(A), was found to be more abundantly expressed in the PC. These results suggest that GABA functions as an excitatory modulator for PC neurons via mainly GABA(B) receptors.

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  • Waggle dance effect: dancing in autumn reduces the mass loss of a honeybee colony

    Ryuichi Okada, Tadaaki Akamatsu, Kanako Iwata, Hidetoshi Ikeno, Toshifumi Kimura, Mizue Ohashi, Hitoshi Aonuma, Etsuro Ito

    JOURNAL OF EXPERIMENTAL BIOLOGY   215 ( 10 ) 1633 - 1641  2012.05  [Refereed]

     View Summary

    A honeybee informs her nestmates about the location of a profitable food source that she has visited by means of a waggle dance: a round dance and a figure-of-eight dance for a short- and long-distance food source, respectively. Consequently, the colony achieves an effective collection of food. However, it is still not fully understood how much effect the dance behavior has on the food collection, because most of the relevant experiments have been performed only in limited locations under limited experimental conditions. Here, we examined the efficacy of the waggle dances by physically preventing bees from dancing and then analyzing the changes in daily mass of the hive as an index of daily food collection. To eliminate place-and year-specific effects, the experiments were performed under fully natural conditions in three different cities in Japan from mid September to early October in three different years. Because the experiments were performed in autumn, all six of the tested colonies lost mass on most of the experimental days. When the dance was prevented, the daily reduction in mass change was greater than when the dance was allowed, i.e. the dance inhibited the reduction of the hive mass. This indicates that dance is effective for food collection. Furthermore, clear inhibition was observed on the first two days of the experiments; after that, inhibition was no longer evident. This result suggests that the bee colony adapted to the new environment.

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  • Molecular dynamics simulations for glutamate-binding and cleft-closing processes of the ligand-binding domain of GluR2

    Okimasa Okada, Kei Odai, Tohru Sugimoto, Etsuro Ito

    BIOPHYSICAL CHEMISTRY   162   35 - 44  2012.03  [Refereed]

     View Summary

    The gating of ion channel of ionotropic glutamate receptors is controlled by the structural change of the ligand-binding domain of GluR2. We examined the roles of residues in the glutamate-binding and cleft-closing mechanisms by molecular dynamics (MD) simulations. A glutamate entered the cleft deeply within the order of nanoseconds and the cleft locked the glutamate completely at 15 ns in an MD run. TYR450 seemed to regulate the orientation of the glutamate upon binding by cation-pi interaction. A semi-open state was identified in the free energy profile evaluated with the structures on the spontaneously glutamate-bound and cleft-closed pathway by the unbiased MD simulations for the first time to our knowledge. In the semi-open state, the two sub-domains were bridged by two hydrogen bonds of GLU705 in the sub-domain 2 with TYR732 in the sub-domain 1 and with the glutamate bound to the sub-domain 1 until the transition to the closed state. (C) 2011 Elsevier RV. All rights reserved.

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  • 1D1534 Insulin and glucose for memory in a snail(Development, Differentiation, Neuroscience,Oral Presentation,The 50th Annual Meeting of the Biophysical Society of Japan)

    Ito Etsuro, Okada Ryuichi, Morikawa Mika, Takigami Satoshi, Okuta Akiko, Sakakibara Manabu

    Seibutsu Butsuri   52   S26  2012

    DOI CiNii

  • Insulin and memory in Lymnaea

    Ito E, Okada R, Sakamoto Y, Otshuka E, Mita K, Sunada H, Sakakibara M

    Acta biologica Hungarica   63 ( suppl 2 ) 194 - 201  2012

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  • Mathematical analysis of the honeybee waggle dance.

    R Okada, H Ikeno, T Kimura, Mizue Ohashi, H Aonuma, E Ito

    Acta biologica Hungarica   63 Suppl 2   75 - 9  2012  [Refereed]  [International journal]

     View Summary

    A honeybee informs her nestmates of the location of a flower by doing a waggle dance. The waggle dance encodes both the direction of and distance to the flower from the hive. To reveal how the waggle dance benefits the colony, we created a Markov model of bee foraging behavior and performed simulation experiments by incorporating the biological parameters that we obtained from our own observations of real bees as well as from the literature. When two feeders were each placed 400 m away from the hive in different directions, a virtual colony in which honeybees danced and correctly transferred information (a normal, real bee colony) made significantly greater numbers of successful visits to the feeders compared to a colony with inaccurate information transfer. Howerer, when five feeders were each located 400 m from the hive, the inaccurate information transfer colony performed better than the normal colony. These results suggest that dancing's ability to communicate accurate information depends on the number of feeders. Furthermore, because non-dancing colonies always made significantly fewer visits than those two colonies, we concluded that dancing behavior is beneficial for hives' ability to visit food sources.

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  • GABAergic effects on the slow oscillatory neural activities in the procerebrum of Limax

    Kobayashi S, Ito E

    Acta Biologica Hungarica   63   217 - 221  2012  [Refereed]

  • Analysis of DNA endoreplication in the brain neurons in the terrestrial slug Limax valentianus.

    Matsuo R, Yamagishi M, Ito E

    Acta Biol Hung   63 (suppl. 2)   171 - 178  2012  [Refereed]

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  • Expression of Asn-d-Trp-Phe-NH2 in the brain of the terrestrial slug Limax valentianus

    Ryota Matsuo, Suguru Kobayashi, Fumihiro Morishita, Etsuro Ito

    COMPARATIVE BIOCHEMISTRY AND PHYSIOLOGY B-BIOCHEMISTRY & MOLECULAR BIOLOGY   160 ( 2-3 ) 89 - 93  2011.10  [Refereed]

     View Summary

    The tripeptide Asn-d-Trp-Phe-NH2 (NdWFamide) is a D-amino acid-containing cardioexcitatory peptide initially isolated from Aplysia. Previously we detected NdWFamide immunoreactivity in the visceral giant cells, the largest neurons in the brain of the terrestrial slug Limax located at the dorsal surface of the visceral ganglia. In the present study, we further analyzed the morphological features of these neurons by an intracellular injection of Lucifer yellow, and found that these neurons extend neurites out of the brain through at least 5 nerve bundles. We then isolated a gene and a cDNA clone potentially encoding a NdWFamide precursor, and investigated expression at the levels of mRNA and protein in Limax. The NdWFamide gene consists of 5 exons spanning at least 17 kb of the genome, and its open reading frame extends over 3 exons. The spatial expression pattern of NdWFamide mRNA was almost identical to that of the NdWFamide peptide, with some minor discrepancies in between. Although the most remarkable expression was evident in the visceral giant cells, we also found the expression of NdWFamide mRNA and peptide in the cerebral and pedal ganglia. These results suggest the involvement of NdWFamide in the regulation of a broad area of the slug&apos;s body. (C) 2011 Elsevier Inc. All rights reserved.

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  • Highly Sensitive Determination of Hydrogen Peroxide and Glucose by Fluorescence Correlation Spectroscopy

    Satoshi Watabe, Yuki Sakamoto, Mika Morikawa, Ryuichi Okada, Toshiaki Miura, Etsuro Ito

    PLOS ONE   6 ( 8 ) e22955  2011.08  [Refereed]

     View Summary

    Background: Because H(2)O(2) is generated by various oxidase-catalyzed reactions, a highly sensitive determination method of H(2)O(2) is applicable to measurements of low levels of various oxidases and their substrates such as glucose, lactate, glutamate, urate, xanthine, choline, cholesterol and NADPH. We propose herein a new, highly sensitive method for the measurement of H(2)O(2) and glucose using fluorescence correlation spectroscopy (FCS).
    Methodology/Principal Findings: FCS has the advantage of allowing us to determine the number of fluorescent molecules. FCS measures the fluctuations in fluorescence intensity caused by fluorescent probe movement in a small light cavity with a defined volume generated by confocal illumination. We thus developed a highly sensitive determination system of H(2)O(2) by FCS, where horseradish peroxidase (HRP) catalyzes the formation of a covalent bond between fluorescent molecules and proteins in the presence of H(2)O(2). Our developed system gave a linear calibration curve for H(2)O(2) in the range of 28 to 300 nM with the detection limit of 8 nM. In addition, by coupling with glucose oxidase (GOD)-catalyzed reaction, the method allows to measure glucose in the range of 80 nM to 1.5 mu M with detection limit of 24 nM. The method was applicable to the assay of glucose in blood plasma. The mean concentration of glucose in normal human blood plasma was determined to be 4.9 mM.
    Conclusions/Significance: In comparison with commercial available methods, the detection limit and the minimum value of determination for glucose are at least 2 orders of magnitude more sensitive in our system. Such a highly sensitive method leads the fact that only a very small amount of plasma (20 nL) is needed for the determination of glucose concentration in blood plasma.

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  • Multiple Subtypes of Serotonin Receptors in the Feeding Circuit of a Pond Snail

    Ryo Kawai, Suguru Kobayashi, Yutaka Fujito, Etsuro Ito

    ZOOLOGICAL SCIENCE   28 ( 7 ) 517 - 525  2011.07  [Refereed]

     View Summary

    In the central nervous system of the pond snail Lymnaea stagnalis, serotonergic transmission plays an important role in controlling feeding behavior. Recent electrophysiological studies have claimed that only metabotropic serotonin (5-HT(2)) receptors, and not ionotropic (5-HT(3)) receptors, are used in synapses between serotonergic neurons (the cerebral giant cells, CGCs) and the follower buccal motoneurons (the B1 cells). However, these data are inconsistent with previous results. In the present study, we therefore reexamined the serotonin receptors to identify the receptor subtypes functioning in the synapses between the CGCs and the B1 cells by recording the compound excitatory postsynaptic potential (EPSP) of the B1 cells evoked by a train of stimulation to the CGC in the presence of antagonists: cinanserin for 5-HT(2) and/or MDL72222 for 5-HT(3). The compound EPSP amplitude was partially suppressed by the application of these antagonists. The rise time of the compound EPSP was longer in the presence of MDL72222 than in that of cinanserin. These results suggest that these two subtypes of serotonin receptors are involved in the CGC-B1 synapses, and that these receptors contribute to compound EPSP. That is, the fast component of compound EPSP is mediated by 5-HT(3)-like receptors, and the slow component is generated via 5-HT(2)-like receptors.

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  • Direct Observation of Dimerization between Different CREB1 Isoforms in a Living Cell

    Hisayo Sadamoto, Kenta Saito, Hideki Muto, Masataka Kinjo, Etsuro Ito

    PLOS ONE   6 ( 6 ) e20285  2011.06  [Refereed]

     View Summary

    Cyclic AMP-responsive element binding protein 1 (CREB1) plays multiple functions as a transcription factor in gene regulation. CREB1 proteins are also known to be expressed in several spliced isoforms that act as transcriptional activators or repressors. The activator isoforms, possessing the functional domains for kinase induction and for interaction with other transcriptional regulators, act as transcriptional activators. On the other hand, some isoforms, lacking those functional domains, are reported to be repressors that make heterodimers with activator isoforms. The complex and ingenious function for CREB1 arises in part from the variation in their spliced isoforms, which allows them to interact with each other. To date, however, the dimerization between the activator and repressor isoforms has not yet been proved directly in living cells. In this study, we applied fluorescence cross-correlation spectroscopy (FCCS) to demonstrate direct observation of dimerization between CREB1 activator and repressor. The FCCS is a well established spectroscopic method to determine the interaction between the different fluorescent molecules in the aqueous condition. Using differently labeled CREB1 isoforms, we successfully observed the interaction of CREB1 activator and repressor via dimerization in the nuclei of cultured cells. As a result, we confirmed the formation of heterodimer between CREB1 activator and repressor isoforms in living cells.

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  • DNA endoreplication in the brain neurons during body growth of an adult slug

    Miki Yamagishi, Etsuro Ito, Ryota Matsuo

    Journal of Neuroscience   31 ( 15 ) 5596 - 5604  2011.04  [Refereed]

     View Summary

    Endoreplication is DNA synthesis without cell division. Giant neurons observed in the brains of mollusks are thought to be generated as a result of DNA endoreplication. It has been hypothesized that neuronal size becomes larger in parallel with an increase in body size and that DNA endoreplication is involved in this process to meet the increasing demand for macromolecules in neurons. Thereis, however, no experimental evidence for this hypothesis to date. In the present study, we investigated the following quantitatively: (1) the size of the brain and each ganglion, (2) the size of identified neurons,(3) the total number of neurons undergoing DNA endoreplication, (4) the total number of the neurons containing a cardioexcitatory peptide, and (5) the gene expression level per neuron, using terrestrial slugs whose body growth was regulated through the amount of food supplied in the laboratory. The body growth was accompanied by increases in the sizes of both neurons and ganglia and triggered more frequent DNA endoreplication events in each ganglion of the growth-promoted slugs, without increasing the total number of neurons. Increase in the neuronal size also involved the increase in the amount of transcripts expressed in a single neuron. This is the first quantitative evidence showing that the DNA endoreplication, neuronal size, and gene expression are increased concomitantly with body growth in adult mollusks. © 2011 the authors.

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  • Immunohistochemical demonstration of cholinergic structures in central ganglia of the slug (Limax maximus, Limax valentianus)

    Loredana D'Este, Arianna Casini, Shin Kimura, Jean-Pierre Bellier, Etsuro Ito, Hiroshi Kimura, Tindaro G. Renda

    Neurochemistry International   58 ( 5 ) 605 - 611  2011.04  [Refereed]

     View Summary

    Immunohistochemical techniques were used to study the distribution of cholinergic neurons containing choline acetyltransferase of the common type (cChAT), the synthetic enzyme of acetylcholine, in the central nervous system of the slug Limax maximus and Limax valentianus. Because the antiserum applied here was raised against a recombinant protein encoded by exons 7 and 8 of the rat gene for ChAT, three methods were used in order to validate antibody specificity for the Limax counterpart enzyme. Western blot combined with ChAT activity assay following native gel electrophoresis and immunoprecipitation analysis both indicated that immunoreactive Limax brain molecules were capable of synthesizing acetylcholine. Western blot after denatured gel electrophoresis of Limax brain extracts revealed a single band of about 67 kDa. All findings obtained with these three methods clearly indicated that the antiserum effectively recognized Limax cChAT. 1400 neuronal cell bodies positive for cChAT, mainly small to medium-sized, were found in various brain regions in the buccal, cerebral, pleural, parietal, visceral and pedal ganglia. cChAT immunoreactive nerve fibers were distributed extensively in the neuropil, connectives and commissures of these central ganglia. The map of cChAT-positive cells provided here are valuable for understanding the cholinergic mechanism in the slug brain, as well as giving an important hint to clarifying the mechanisms of learning and memory in higher vertebrates including humans. © 2011 Elsevier Ltd. All rights reserved.

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  • Two pairs of tentacles and a pair of procerebra: Optimized functions and redundant structures in the sensory and central organs involved in olfactory learning of terrestrial pulmonates

    Ryota Matsuo, Suguru Kobayashi, Miki Yamagishi, Etsuro Ito

    Journal of Experimental Biology   214 ( 6 ) 879 - 886  2011.03  [Refereed]

     View Summary

    Terrestrial pulmonates can learn olfactory-aversion tasks and retain them in their long-term memory. To elucidate the cellular mechanisms underlying learning and memory, researchers have focused on both the peripheral and central components of olfaction: two pairs of tentacles (the superior and inferior tentacles) and a pair of procerebra, respectively. Data from tentacleamputation experiments showed that either pair of tentacles is sufficient for olfactory learning. Results of procerebrum lesion experiments showed that the procerebra are necessary for olfactory learning but that either one of the two procerebra, rather than both, is used for each olfactory learning event. Together, these data suggest that there is a redundancy in the structures of terrestrial pulmonates necessary for olfactory learning. In our commentary we exemplify and discuss functional optimization and structural redundancy in the sensory and central organs involved in olfactory learning and memory in terrestrial pulmonates. © 2011 Published by The Company of Biologists Ltd.

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  • Does Conditioned Taste Aversion Learning in the Pond Snail Lymnaea stagnalis Produce Conditioned Fear?

    Serina Kita, Ryuji Hashiba, Saya Ueki, Yukari Kimoto, Yoshito Abe, Yuta Gotoda, Ryoko Suzuki, Eriko Uraki, Naohisa Nara, Akira Kanazawa, Dai Hatakeyama, Ryo Kawai, Yutaka Fujito, Ken Lukowiak, Etsuro Ito

    BIOLOGICAL BULLETIN   220 ( 1 ) 71 - 81  2011.02  [Refereed]

     View Summary

    In conditioned taste aversion (CTA) training performed on the pond snail Lymnaea stagnalis, a stimulus (the conditional stimulus, CS; e.g., sucrose) that elicits a feeding response is paired with an aversive stimulus (the unconditional stimulus, US) that elicits the whole-body withdrawal response and inhibits feeding. After CTA training and memory formation, the CS no longer elicits feeding. We hypothesize that one reason for this result is that after CTA training the CS now elicits a fear response. Consistent with this hypothesis, we predict the CS will cause (1) the heart to skip a beat and (2) a significant change in the heart rate. Such changes are seen in mammalian preparations exposed to fearful stimuli. We found that in snails exhibiting long-term memory for one-trial CTA (i.e., good learners) the CS significantly increased the probability of a skipped heartbeat, but did not significantly change the heart rate. The probability of a skipped heartbeat was unaltered in control snails given backward conditioning (US followed by CS) or in snails that did not acquire associative learning (i.e., poor learners) after the one-trial CTA training. These results suggest that as a consequence of acquiring CTA, the CS evokes conditioned fear in the conditioned snails, as evidenced by a change in the nervous system control of cardiac activity.

  • Quantitative Changes in CREB Isoforms and Variants of the Snail Brain in Long-term Memory

    SADAMOTO Hisayo, ITO Etsuro

    Seibutsu Butsuri   51 ( 1 ) 18 - 21  2011.01

     View Summary

    The transcription factor, cAMP response element binding protein (CREB), is involved in formation of long-term memory in the brain of many species. There are at least two different isoforms of CREB: the activator isoform (CREB1) and the repressor isoform (CREB2). By use of quantitative real-time PCR, we succeeded in determining CREB1 and CREB2 mRNA copy numbers in the single neuron that plays a key role in the associative learning of the pond snail Lymnaea stagnalis. Further, we characterized the spliced variants of CREB1 mRNA and analyzed the relation between the learning behavior of snails and the expression pattern of these CREB1 mRNA variants in the brain of the learned snails. We here discuss the function and the quantitative changes in CREB isoforms and variants of the snail brain in long-term memory.<br>

    DOI CiNii

  • 3F1048 Blockade of long-term potentiation and long-term memory of conditioned taste aversion by application of antibody for insulin receptor(3F Neuroscience & Sensory systems, Neuronal Circuit & Information processing, Behavior,The 49th Annual Meeting of the Biophysical Society of Japan)

    Ito Etsuro, Okuta Akiko, Sunada Hiroshi, Sakakibara Manabu

    Seibutsu Butsuri   51   S126  2011

    DOI CiNii

  • Spontaneous regeneration of the central nervous system in gastropods

    Ryota Matsuo, Etsuro Ito

    Biological Bulletin   221 ( 1 ) 35 - 42  2011  [Refereed]

     View Summary

    Of all organs in mammals including humans, the brain has the most limited regenerative capacity after injury or damage. In spite of extensive efforts to treat ischemic/stroke injury of the brain, thus far no reliable therapeutic method has been developed. However, some molluscan species show remarkable brain regenerative ability and can achieve full functional recovery following injury. The terrestrial pulmonates are equipped with a highly developed olfactory center, called the procerebrum, which is involved in olfactory discrimination and odor-aversion learning. Recent studies revealed that the procerebrum of the land slug can spontaneously recover structurally and functionally relatively soon after injury. Surprisingly, no exogenous interventions are required for this reconstitutive repair. The neurogenesis continues in the procerebrum in adult slugs as in the hippocampus and the olfactory bulb of mammals, and the reconstitutive regeneration seems to be mediated by enhanced neurogenesis. In this review, we discuss the relationship between neurogenesis and the regenerative ability of the brain, and also the evolutionary origin of the brain structures in which adult neurogenesis has been observed. © 2011 Marine Biological Laboratory.

    DOI PubMed

    Scopus

    13
    Citation
    (Scopus)
  • Markov Model of Honeybee Social Behavior

    Ryuichi Okada, Hidetoshi Ikeno, Toshifumi Kimura, Mizue Ohashi, Hitoshi Aonuma, Etsuro Ito

    INFORMATION-AN INTERNATIONAL INTERDISCIPLINARY JOURNAL   13 ( 3B ) 1115 - 1130  2010.05  [Refereed]

     View Summary

    It is well established that honeybees inform their nestmates of the location of flowers they have visited by a unique behavior called a "waggle dance". To evaluate the efficacy of this dance in terms of food collection, we constructed a Markov model for foraging behavior. The computer simulation showed that our model faithfully expressed actual bee behavior; revealed that a colony in which honeybees danced and correctly transferred information made 2.15 times more successful visits to food sources compared to a colony with non-accurate information transfer; and suggested that the waggle dance is effective only under particular conditions.

  • 3P257 Lon-term potentiation induced by insulin-like peptide in the central nervous system of a snail(Neuronal Circuit & Information processing,The 48th Annual Meeting of the Biophysical Society of Japan)

    Ito Etsuro, Murakami Jun, Okada Ryuichi, Okuta Akiko, Sadamoto Hisayo

    Seibutsu Butsuri   50 ( 2 ) S190  2010

    DOI CiNii

  • Glutamate uptake system in Lymnaea stagnalis

    Ito Etsuro, Hatakeyama Dai, Mita Koichi, Kobayashi Suguru, Hiripi Laszlo, Elekes Karoly

    COMPARATIVE BIOCHEMISTRY AND PHYSIOLOGY A-MOLECULAR & INTEGRATIVE PHYSIOLOGY   153A ( 2 ) S152  2009.06  [Refereed]

    DOI

  • 3P-194 The role of FMRFamidergic neurons in the olfactory center of Limax(Neuronal Circuit & Information processing,The 47th Annual Meeting of the Biophysical Society of Japan)

    Hattori Mariko, Kobayashi Suguru, Matsuo Ryota, Ito Etsuro

    Seibutsu Butsuri   49   S183 - S184  2009

    DOI CiNii

  • 3P-190 Roles of glutamate transport systems in reeding rhythm generation of pond snails(Neuroscience & Sensory systems,The 47th Annual Meeting of the Biophysical Society of Japan)

    Hatakeyama Dai, Mita Koichi, Kobayashi Suguru, Sadamoto Hisayo, Ito Etsuro

    Seibutsu Butsuri   49   S183  2009

    DOI CiNii

  • 2P-202 GABA receptor-mediated modulation of oscillatory nenronal activity in slog olfactory center(Neuronal Circuit & Information processing,The 47th Annual Meeting of the Biophysical Society of Japan)

    Kobayashi Suguru, Hattori Mariko, Matsuo Ryota, Ito Etsuro

    Seibutsu Butsuri   49   S138 - S139  2009

    DOI CiNii

  • A movement index for evaluation of honeybee activity in the observation hive

    Ikeno Hidetoshi, Okada Ryuichi, Ohashi Mizue, Kimura Toshifumi, Akamatsu Tadaaki, Ito Etsuro

    COMPARATIVE BIOCHEMISTRY AND PHYSIOLOGY B-BIOCHEMISTRY & MOLECULAR BIOLOGY   151 ( 4 ) 456  2008.12  [Refereed]

    DOI

  • The tracking system of honeybee behavior in the observation hive

    Kimura Toshifumi, Ikeno Hidetoshi, Ohashi Mizue, Okada Ryuichi, Ito Etsuro

    COMPARATIVE BIOCHEMISTRY AND PHYSIOLOGY B-BIOCHEMISTRY & MOLECULAR BIOLOGY   151 ( 4 ) 455 - 456  2008.12  [Refereed]

    DOI

  • Locomotion patterns of honeybee in the hive

    Okada Ryuichi, Ikeno Hidetoshi, Kimura Toshifumi, Ohashi Mizue, Aonuma Hitoshi, Ito Etsuro

    COMPARATIVE BIOCHEMISTRY AND PHYSIOLOGY B-BIOCHEMISTRY & MOLECULAR BIOLOGY   151 ( 4 ) 456  2008.12  [Refereed]

    DOI

  • Morphology of C6 glioma cells on a water-repellent fractal alkyl ketene dimer surface

    Wei-wei Hu, Hu Yan, Naoko Birukawa, Masashi Abe, Etsuro Ito, Kaoru Tsujii, Zhong Chen, Akihisa Urano

    CURRENT NANOSCIENCE   4 ( 3 ) 224 - 231  2008.08  [Refereed]

     View Summary

    In many in vitro cultures, cells may change their morphology, probably caused by adherence to the surface of the culture dish. Since a fractal alkyl ketene dimer (AKD) surface provides super water-repellency with a contact angle of 174, we considered that it might provide an improved surface environment for the growth and differentiation of cells by preventing intimate adhesion. C6 glioma cells which were selected to test the effects of the fractal surface, were cultured on a conventional surface, a smooth AKD surface or a fractal AKD surface. On the conventional and smooth AKD surfaces, cells developed bipolar or multipolar shapes with enlarged cell bodies and neurite-like processes. In contrast, cells cultured on the fractal AKD surface presented fine filopodium-like processes like protoplasmic astrocytes in vivo, and higher morphological complexity was revealed by fractal analysis. Reconstruction of three-dimensional shape indicated that cells on the fractal surface were globular, whereas those on the conventional surface were rather flat. Our results suggest that C6 glioma cells on a fractal AKD surface show features of natural astrocytes with their elaborate morphology. The fractal surface thus may provide a new and natural culture environment for experimental assessment of glial structure and function.

  • 2P-252 Regulatory mechanism controlling serotonergic neurotransmission in learning snails(The 46th Annual Meeting of the Biophysical Society of Japan)

    Sadamoto Hisayo, Kobayashi Suguru, Ito Etsuro

    Seibutsu Butsuri   48   S114  2008

    DOI CiNii

  • 1P218 GABAergic neurotransmisson in odor information processing of the terrestrial mollusk Limax(Neural network and brain computing,Poster Presentations)

    Kobayashi Suguru, Matsuo Ryota, Ito Etsuro

    Seibutsu Butsuri   47   S78  2007

    DOI CiNii

  • 1P371 The role of GABA receptor in odor information processing in Limax varentianus(14. Ion channels and receptors,Poster Session,Abstract,Meeting Program of EABS & BSJ 2006)

    Kobayashi Suguru, Matsuo Ryota, Ito Etsuro

    Seibutsu Butsuri   46 ( 2 ) S239  2006

    DOI CiNii

  • 1SC53 Single-neuron analysis for change in expression level of CREB genes during associative learning in pond snail

    Ito E.

    Seibutsu Butsuri   44   S11  2004

    DOI CiNii

  • Dual Role of Cyclic AMP-Dependent Protein Kinase in Neuritogenesis and Synaptogenesis during Neuronal Differentiation

    Takuro Tojima, Suguru Kobayashi, Etsuro Ito

    Journal of Neuroscience Research   74 ( 6 ) 829 - 837  2003.12  [Refereed]

     View Summary

    To create precise neural circuits in the nervous system, neuritogenesis and synaptogenesis are the critical cellular processes during neuronal differentiation. We examined the cyclic AMP (cAMP)-responsible signaling pathways for regulating neuritogenesis and synaptogenesis in NG108-15 cells. A rise in intracellular cAMP concentration by a membrane-permeable cAMP analog, dibutyryl cAMP (DBcAMP), led to an increase in the number of neurites and varicosities. Inhibition of cAMP-dependent protein kinase (PKA) activity by a PKA inhibitor (H89) accelerated this neuritogenesis and neurite outgrowth rate. Treatment with H89, however, decreased the number of varicosities and the frequency of postsynaptic miniature current recorded in the cultured cells, resulting in suppression of synaptogenesis. Immunoblot analyses revealed that PKA activity mediates phosphorylation of a gene transcription factor, cAMP-response element binding protein (CREB). On the other hand, inhibition of a mitogen-activated protein kinase (MAPK)/extracellular signal-regulated kinase (ERK) pathway by a MAPK/ERK kinase (MEK) inhibitor (PD98059) suppressed both neuritogenesis and neurite outgrowth without CREB phosphorylation. These results suggest strongly that PKA simultaneously plays two different roles in neuronal differentiation: inhibition of neuritogenesis and stimulation of synaptogenesis, via CREB-mediated gene expression. © 2003 Wiley-Liss, Inc.

    DOI PubMed

    Scopus

    57
    Citation
    (Scopus)
  • Theoretical Study of Activation Mechanism of Glutamate Recepter

    Shiomitsu E., Kubo M., Odai K., Sugimoto T., Ito E.

    Seibutsu Butsuri   43   S91  2003

    DOI CiNii

  • Quantitative measurement of CREB mRNAs in single neurons

    Ito E., Sadamoto H., Wagatsuma A., Sugai R.

    Seibutsu Butsuri   43   S235  2003

    DOI CiNii

  • 1L1415 Effects of ligand-receptor electrostatic interactions on molecular recognition of glutamate receptor

    Kubo M., Shiomitsu E., Odai K., Sugimoto T., Suzuki H., Ito E.

    Seibutsu Butsuri   42 ( 2 ) S70  2002

    DOI CiNii

  • Learning and memory in the pond snail Lymnaea stagnalis: Analyses from behavior to molecules

    Etsuro Ito

    Nippon Suisan Gakkaishi (Japanese Edition)   68 ( 6 ) 911 - 912  2002  [Refereed]

    DOI

    Scopus

  • An ab initio study of structural and electronic states of glutamic acid in a vacuum and in aqueous solution

    Odai K., Sugimoto T., Kubo M., Ito E.

    Seibutsu Butsuri   41   S185  2001

    DOI CiNii

  • Involvement of cofilin phosphorylation in neuritogenesis in a neuroblastoma x glioma hybrid cell line

    Tojima T, Takahashi M, Obinata T, Ito E

    Seibutsu Butsuri   41   S139  2001

    DOI CiNii

  • Vibrational excitation of glutamate receptor by glutamate binding

    Kubo M., Shiomitsu E., Odai K., Sugimoto T., Suzuki H., Ito E.

    Seibutsu Butsuri   41   S103  2001

    DOI CiNii

  • Time-sharing contributions of A- and D-type K+ channels to the integration of high-frequency sequential excitatory post synaptic potentials at a model dendrite in rats

    H Takagi, R Sato, M Mori, T Matsumoto, M Saito, E Ito, H Suzuki

    NEUROSCIENCE LETTERS   289 ( 3 ) 169 - 172  2000.08  [Refereed]

     View Summary

    A- and D-type K+ channels (KA and KD channels) have unique physiological properties that play important roles in the integration of excitatory post synaptic potentials (EPSPs) in neuronal dendrites. These functions were analyzed using a computer program, NEURON, to simulate high-frequency sequential synaptic inputs, that can induce long-term potentiation (LTP). We paid close attention to the stability of the reduction of sequential EPSPs. When either KA or KD channels were included in models, the EPSP reduction ratios were less stable than containing both KA and KD channels. When both KA and KD channels were present in the model, the variance of EPSP reduction ratios was significantly smaller in comparison with that in the presence of either KA or KD channels alone. We thus concluded that the co-existence of KA and KD channels is necessary to produce stable EPSPs during the high-frequency synaptic stimulation necessary for induction of LTP. (C) 2000 Elsevier Science Ireland Ltd. All rights reserved.

  • 発生・成長過程に視点をおいて眺めた『学習・記憶のメカニズム』

    伊藤 悦朗, 定本 久世

    比較生理生化学   17 ( 1 ) 4 - 10  2000.03

    DOI CiNii

  • Increase of intracellular Ca^<2+>and propagation of intercellular Ca^<2+>in rat cultured astrocytes evoked by mechanical stimulation

    Ito E., Shiga H., Yamane Y.

    Seibutsu Butsuri   40   S210  2000

    DOI CiNii

  • Changes in electronic states of GABA and glutamic acid caused by their interactions with glutamate receptor

    Odai K., Sugimoto T., Kubo M., Ito E.

    Seibutsu Butsuri   40   S50  2000

    DOI CiNii

  • Effect of molecular vibration on activation of glutamate receptor

    Kubo M., Odai K., Sugimoto T., Ito E.

    Seibutsu Butsuri   40   S179  2000

    DOI CiNii

  • Dynamics of astrocyte adhesion as analyzed by a combination of atomic force microscopy and immunocytochemistry: the involvement of actin filaments and connexin 43 in the early stage of adhesion

    Y Yamane, H Shiga, H Asou, H Haga, K Kawabata, K Abe, E Ito

    ARCHIVES OF HISTOLOGY AND CYTOLOGY   62 ( 4 ) 355 - 361  1999.10  [Refereed]

     View Summary

    We observed the time-dependent morphological alteration of astrocytes during their adhesion by atomic force microscopy (AFM) and investigated the relationships between this morphological alteration and the localization of actin filaments and connexin 43 by immunocytochemistry. The fine processes observed as fine ridge-like structures by AFM were closely concerned with ac tin filaments by immunocytochemistry, During the adhesion of astrocytes, actin filaments appeared to be aligned regularly beyond the borders among different cells. Detectable connexin immunoreactivity was changed in the following regions: 1) the tips of fine cell processes and the cell margin when astrocytes started to adhere; 2) the border of cells when astrocytes tightly adhered; and 3) non-specific sites when astrocytes became a cluster. In the former two cases, the immunopositive spots for connexin were observed to colocalize with the tips of cell processes with actin filaments. These results strongly suggest that connexin associated with actin filaments at the tip of cell processes plays an important role in the early stage of the adhesion of astrocytes. These observations afford valuable clues for understanding the glial communication.

  • Atomic force microscopic and immunocytochemical study of glial cell to cell adhesion.

    Yamane Y., Shiga H., Asou H., Haga H., Kawabata K., Abe K., Ito E.

    Seibutsu Butsuri   39   S57  1999

    DOI CiNii

  • Comparison of the CGC responses between different preparations in Lymnaea stagnalis.

    Suzuki T., Kojima S., Kobayashi S., Ito E.

    Seibutsu Butsuri   39   S64  1999

    DOI CiNii

  • Elasticity Mapping of Living Cells by AFM and Immunofluorescence Observation of Cytoskeleton.

    Haga H., Sasaki S., Kawabata K., Ito E., Ushiki T., Sambongi T.

    Seibutsu Butsuri   39   S37  1999

    DOI CiNii

  • Imaging Viscoelasticity of Living Cells using Force Modulation Mode in AFM

    Nagayama M., Haga H., Kawabata K., Ito E., Sambongi T.

    Seibutsu Butsuri   39   S37  1999

    DOI CiNii

  • Strateges for Biophysical Approaches to Brain and Neural Systems in the Next Century

    Seibutsu Butsuri   39   S25  1999

    DOI CiNii

  • Spatial and temporal viscoelastic imaging of living fibroblasts by atomic force microscopy

    H Haga, S Sasaki, K Kawabata, E Ito, K Abe, T Sambongi

    BIOLOGICAL PHYSICS   487   229 - 234  1999

     View Summary

    We have investigated viscoelastic properties of living mouse fibroblasts (NIH3T3) in a physiological condition using both force mapping and force modulation modes in atomic force microscopy. Spatial distribution of the elastic moduli has been measured using the force mapping mode. The nucleus area of the cell is about 10 times softer than the cytoplasm. Temporal changes in shape and viscoelasticity of developing lamellipodia have been captured using the force modulation mode. The dynamic changes were succeeded in capturing with time resolution of 10 minutes.

  • Time dependent viscoelastic image of living nerve cells using AFM

    K Kawabata, H Ishizuka, T Nitta, H Haga, E Ito, K Abe, T Ushiki, T Sambongi

    BIOLOGICAL PHYSICS   487   235 - 239  1999

     View Summary

    The topographic and viscoelastic images of the nerve cell (NG108-15) living in the culture medium were successfully obtained in the force modulation mode using atomic force microscopy(AFM), We found that there exists variation of elasticity in the cell, To compare the elastic results with F-actin network of cytoskeleton which is considered as a possible origin for cell stiffness, the fluorescence observation was made on the fu;ed cells just after the AFM measurements. The results show no clear correspondence between density of F-actin and stiffness of the cells.

  • Mechanisms of sensory processing and learning in the gastropods

    ITO Etsuro, KAWAHARA Shigenori, SAKAKIBARA Manabu, NAGAHAMA Tatsumi

    Seibutsu Butsuri   37 ( 4 ) 150 - 154  1997.07

     View Summary

    Central nervous systems of gastropods are useful to study the mechanisms of sensory processings and their related learning. Although the gastropods present their complicated behavior, their many neurons have already been identified and their neural networks are analyzed well. Here by reviewing the most advanced results in the cell physiology of olfaction, gustation, vision and their learning, we introduce a promising way for brain study in the future biophysics.

    DOI CiNii

  • Tumor Necrosis Factor‐α (TNF‐α), Interferon‐γ, and Interleukin‐6 but Not TNF‐β Induce Differentiation of Neuroblastoma Cells: The Role of Nitric Oxide

    Etsuro Ito, Kotaro Oka, Carlos Collin, Bernard G. Schreurs, Manabu Sakakibara, Daniel L. Alkon

    Journal of Neurochemistry   62 ( 4 ) 1337 - 1344  1994  [Refereed]

     View Summary

    Abstract: Abstract: Previous observations have implicated GABA as a neurotransmitter released by the vestibular sensory neurons („hair cells”) of the snail Hermissenda onto visual sensory neurons, the type B cells, whose cell bodies are the sites of biophysical and biochemical changes during and following Pavlovian conditioning. Still other observations demonstrated that light‐GABA pairings that simulate stimuli presented during Pavlovian conditioning cause prolonged elevatiori of intracellular Ca2+ and transformation of GABA‐induced synaptic inhibition into excitation. Intracellular Ca2+ signals in response to GABA perfused onto the postsynaptic: type B terminal branches are shown here to be prolonged on days after conditioning, but not after control paradigms. These and past results demonstrate two separate sites, i.e., the cell body and the terminal branches, for learning‐induced changes after Pavlovian conditioning. Copyright © 1994, Wiley Blackwell. All rights reserved

    DOI PubMed

    Scopus

    36
    Citation
    (Scopus)
  • DEVELOPMENTAL-STUDY OF SIGNAL TRANSDUCTION IN RAT CEREBELLAR PURKINJE-CELL

    T YOSHIOKA, E ITO, A MIYAZAWA, H TAKAGI

    NEURORECEPTORS, ION CHANNELS AND THE BRAIN     189 - 197  1992  [Refereed]

  • Heterogeneous distribution of glutamate receptor subtypes in hippocampus as revealed by calcium fluorometry

    Y. Kudo, E. Ito, A. Ogura

    Advances in Experimental Medicine and Biology   287   431 - 440  1991  [Refereed]

    PubMed

  • An Extended INDO-CI Study on Protonated Retinal Schiff-Base

    Tohru Sugimoto, Yoshio Kishi, Etsuro Ito, Hideo Suzuki

    journal of the physical society of japan   59 ( 10 ) 3780 - 3790  1990  [Refereed]

     View Summary

    The bond lengths, bond orders, electron densities and optical absorption of the ground state of retinal forming a protonated Schiff-base linkage with a lysine residue (PRSB-Lys) are calculated using the extended INDO-CI molecular orbital method, and the result is compared with the previous one obtained by the π-electron approximation. It is, thus, shown that the π-electron system of PRSB-Lys is appreciably polarized, and that the σ – π interaction in PRSB-Lys is too large to be neglected when a C-C bond in its polyene chain is twisted. It is also shown that the negative counter point-charge exerts influence on the π-electron distribution in a similar way to that shown by the π-electron approximation. © 1990, THE PHYSICAL SOCIETY OF JAPAN. All rights reserved.

    DOI

    Scopus

    5
    Citation
    (Scopus)
  • Topographical heterogeneity of glutamate agonist-induced calcium increase in hippocampus

    Y. Kudo, E. Ito, A. Ogura

    Advances in Experimental Medicine and Biology   268   125 - 133  1990  [Refereed]

    PubMed

  • Semiempiricał Calculations of Force Constants for Torsional and Stretching Vibrations in Excited States of Retinal and Its Related Compounds

    Etsuro Ito, Hiroto Kikuchi, Hideo Suzuki

    Journal of the Physical Society of Japan   57 ( 5 ) 1842 - 1851  1988  [Refereed]

     View Summary

    We consider the ground state (GS), the excited state on absorption (ESA), the virtual ground (VGS) and the deformed excited state (DES) of π-electron system in hexaene, retinal, retinal Schiff-base (RSB), protonated retinal Schiff-base (PRSB) or our model for rhodopsin chromophore, and we semiempirically calculate the following two kinds of force constants for the pairs of bonded atoms in each of the four π-electronic states: (1) the force constants of torsional vibrations
    (2) those of the interactions between torsional and stretching vibrations. The calculations are carried out by our LCAO-ASMO-SCF-CI method for π-electrons, selecting such a part of the total energy of π-electron system that gives a significant contribution to the force constants. © 1988, THE PHYSICAL SOCIETY OF JAPAN. All rights reserved.

    DOI

    Scopus

    6
    Citation
    (Scopus)
  • Theory of Retinal and Its Related Compounds by the Extended INDO-CI Method Taking Account of the Change in Bond Lengths in Consistence with Electronic States

    Tohru Sugimoto, Etsuro Ito, Hideo Suzuki

    Journal of the Physical Society of Japan   57 ( 4 ) 1497 - 1507  1988  [Refereed]

     View Summary

    We consider retinal and its related compounds in planar configuration provided they have no ionic structure, and we extend the ordinary INDO-CI method to calculate their bond lengths in consistence with their electronic states. One of the important features of our extended INDO-CI method is that each bond length is calculated as a function of bond order which is similar to the Coulson type of relation derived by the π-electron approximation. The extended INDO-CI calculations of the bond lengths, electronic structure and optical absorptions of the molecules indicate that the previous results, which were obtained by Suzuki et al. using the π-electron approximation, are reasonable. © 1988, THE PHYSICAL SOCIETY OF JAPAN. All rights reserved.

    DOI

    Scopus

    5
    Citation
    (Scopus)
  • INTERPRETATION OF THE DICHROIC ORIENTATION OF PHYTOCHROME

    T SUGIMOTO, E ITO, H SUZUKI

    PHOTOCHEMISTRY AND PHOTOBIOLOGY   46 ( 4 ) 517 - 523  1987.10  [Refereed]

  • SEMIEMPIRICAL CALCULATION OF FORCE-CONSTANTS OF STRETCHING VIBRATIONS IN EXCITED-STATES OF RETINAL AND ITS RELATED-COMPOUNDS

    H SUZUKI, E ITO, T SUGIMOTO

    JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN   54 ( 12 ) 4861 - 4868  1985.12  [Refereed]

▼display all

Books and Other Publications

  • 軟体動物2 ナメクジの学習記憶,動物は何を考えているのか?:記憶と学習の比較生物学,動物の多様な生き方

    共立出版  2009

  • 身近な動物を使った実験4 ミツバチ,コオロギ,スズメガ

    三共出版  2009

  • 身近な動物を使った実験2 プラナリア,モノアラガイ・ナメクジ,ミミズ

    三共出版  2009

  • 基礎物理

    東京教学社  2009

  • 生物学・医学分野におけるマイクロマニピュレーターの最前線 ~シングル・セル・アイソレーション・システムの開発~,細胞分類・操作技術の最前線

    シーエムシー出版  2008

  • アミノ酸類,気体因子,ホルモンハンドブック新訂eBook版,日本比較内分泌学会編

    南江堂  2007

  • バイオとナノの融合Ⅱ 新生命科学の応用

    北海道大学出版会  2006

  • 神経伝達物質の放出・受容に伴うニューロンの局所的機能と微細形態変化の測定(共著)

    ブレインサイエンス・レビュー2001  2001

  • Thermodynamics of the visual-pigment system(jointly worked)

    The Thermodynamics of the Drug-Receptor Interaction (R.B.Raffa ed), John Wiley & Sons  2001

  • 生体情報とエントロピー -生体情報伝達機構の論理の解明を目指して-(共著)

    培風館  2000

  • アメフラシの記憶学習

    行動生物学  1997

  • Neuromodulation Models for Associative Learnings with Central Pattern Generator in the Poud Snail, Lymnaea stagnalis(jointly worked)

    Nervous Systems and Behavior  1995

  • Developmental Study of Signal Transduction in Rat Cerebellar Purkinje Cell(jointly worked)

    Neuroreceptors, Ion Channels and the Brain  1992

  • Heterogeneous Distribution of Glutamate Subtypes in Hippocampus as Revealed by Calcium Fluorometry(jointly worked)

    Neuroreceptor Mechanisms in Brain  1991

  • Heterogeneous Distribution of Glutamate Receptor Subtypes in Hippocampus as Revealed by Calcium Fluorometry(jointly worked)

    Neuroreceptor Mechanisms in Brain  1991

  • ナメクジの記憶学習

    行動生物学 

▼display all

Misc

  • Insulin and memory in invertebrates.

    Nakai J, Chikamoto N, Fujimoto K, Totani Y, Hatakeyama D, Dyakonova V, Ito E

    Frontiers in Behavioral Neuroscience   16  2022.04

    Article, review, commentary, editorial, etc. (scientific journal)  

    DOI

  • 「脳科学のフロンティア」 脳はどこまでわかってきたか:神経可塑性に着目して

    岡田 龍一, 伊藤 悦朗

    パリティ   28 ( 4 ) 24 - 32  2013  [Refereed]

    Article, review, commentary, editorial, etc. (trade magazine, newspaper, online media)  

    CiNii

  • 動的環境下でのミツバチ採餌行動におけるダンス情報の誤差の効果

    岡田龍一, 池野英利, 木村敏文, 大橋瑞江, 青沼仁志, 伊藤悦朗

    日本動物学会大会予稿集   83rd   128  2012.08

    J-GLOBAL

  • モノアラガイの長期記憶におけるインスリンとグルコースの役割

    伊藤悦朗, 箕田康一, 岡田龍一, 森川美佳, 山岸美貴, 大塚栄美

    日本動物学会中国四国支部会報   ( 64 ) 20  2012

    J-GLOBAL

  • コンピュータシミュレーションによるミツバチ8の字ダンスの採餌行動における効果

    岡田龍一, 池野英利, 木村敏文, 大橋瑞江, 青沼仁志, 伊藤悦朗

    日本動物学会大会予稿集   82nd   145  2011.08

    J-GLOBAL

  • コンピュータシミュレーションによるミツバチの採餌戦略の解析

    岡田龍一, 池野英利, 木村敏文, 大橋瑞江, 青沼仁志, 伊藤悦朗

    日本動物学会中国四国支部会報   ( 63 ) 16  2011

    J-GLOBAL

  • FMRFamide regulates oscillatory activity of the olfactory center in the slug

    Suguru Kobayashi, Mariko Hattori, Karoly Elekes, Etsuro Ito, Ryota Matsuo

    EUROPEAN JOURNAL OF NEUROSCIENCE   32 ( 7 ) 1180 - 1192  2010.10

     View Summary

    In the olfactory center of terrestrial animals, changes in the oscillatory frequency of the local field potential (LFP) are thought to be involved in olfaction-based behavior and olfactory memory. The terrestrial slug Limax has a highly developed olfactory center, the procerebrum, in which the LFP spontaneously oscillates. Although changes in the oscillatory frequency are thought to correspond to the preference for specific odors, our knowledge about the mechanism of this frequency regulation is limited. To clarify the mechanism of the bidirectional frequency changes in the procerebrum, we focused on the neuropeptide Phe-Met-Arg-Phe-NH2 (FMRFamide), which is known to have neuromodulatory functions in invertebrate nervous systems. Application of FMRFamide decreased the oscillatory frequency via G-protein-mediated cascades. Immunohistochemistry showed that FMRFamide-like-immunoreactive neuronal cell bodies are located in the cell mass layer of the procerebrum, projecting their neurites to the neuropile layers. The procerebrum was shown to also receive innervation from other regions of the cerebral ganglion. Furthermore, according to their morphological and projection characteristics, FMRFamide-containing neurons belong to the subpopulations of both bursting and nonbursting neurons in the procerebrum. The mRNA splice variant encoding multiple copies of canonical FMRFamide was specifically expressed in the procerebrum. Taking into account previous results showing that serotonin increases the oscillatory frequency, our results indicate that FMRFamide and serotonin both regulate the LFP frequency but in exactly the opposite direction in the olfactory center of the terrestrial slug.

    DOI

  • Effects of tentacle amputation and regeneration on the morphology and activity of the olfactory center of the terrestrial slug Limax valentianus

    Ryota Matsuo, Suguru Kobayashi, Yoko Tanaka, Etsuro Ito

    JOURNAL OF EXPERIMENTAL BIOLOGY   213 ( 18 ) 3144 - 3149  2010.09

     View Summary

    The tentacles of pulmonates regenerate spontaneously following amputation. The regenerated tentacle is equipped with all the elements necessary for normal olfactory functioning, and the slugs can behave as well as they did before the tentacle amputation. However, it is not known what changes occur to the olfactory center procerebrum in the brain at the morphological and physiological levels. Here, we investigated the innervation of tentacular nerves into the procerebrum by examining the size of the terminal mass (input layer from tentacular nerves) of the procerebrum and also by staining afferent nerves immunohistochemically at 15, 58 and 75 days following unilateral amputation of the superior and inferior tentacles. The size of the terminal mass was significantly decreased, and the Phe-Met-Arg-Phe-NH(2)ergic (FMRFamidergic) afferent nerves disappeared by 15 days following the tentacle amputation. However, the size of the terminal mass had recovered substantially by 58 days, as the tentacle regenerated. The FMRFamidergic innervation into the cerebral ganglion was also restored by this time. An extended recovery (75 days), however, did not result in any further increase in the size of the terminal mass. We also recorded the local field potential (LFP) oscillation in the procerebrum. We found that the oscillatory frequency of the LFP had decreased at 15 days following the tentacle amputation but had recovered at 58 and 75 days. These results suggest that the amputation and regrowth of the tentacle are accompanied by the respective degeneration and re-innervation of olfactory nerves, and these changes in the innervation status affect the basal state of LFP oscillation.

    DOI PubMed

  • 計算機シミュレーションによるミツバチ8の字ダンスの採餌行動における効果

    岡田龍一, 池野英利, 木村敏文, 大橋瑞江, 青沼仁志, 伊藤悦朗

    日本動物学会大会予稿集   81st   155  2010.08

    J-GLOBAL

  • Glutamate Transporters in the Central Nervous System of a Pond Snail

    Dai Hatakeyama, Koichi Mita, Suguru Kobayashi, Hisayo Sadamoto, Yutaka Fujito, Laszlo Hiripi, Karoly Elekes, Etsuro Ito

    JOURNAL OF NEUROSCIENCE RESEARCH   88 ( 6 ) 1374 - 1386  2010.05

     View Summary

    Previous studies on glutamate (GLU) and its receptors in the pond snail Lymnaea stagnalis have suggested that GLU functions as a neurotransmitter in various behaviors, particularly for generation of feeding rhythm. The uptake mechanism of GLU is not yet known in Lymnaea. In the present study, we characterized the GLU transporters and examined their functions in the feeding circuits of the central nervous system (CNS) in Lymnaea. First, measurement of the accumulation of (3)H-labeled GLU revealed the presence of GLU transport systems in the Lymnaea CNS. The highest accumulation rate was observed in the buccal ganglia, supporting the involvement of GLU transport systems in feeding behavior. Second, we cloned two types of GLU transporters from the Lymnaea CNS, the excitatory amino acid transporter (LymEAAT) and the vesicular GLU transporter (LymVGLUT). When we compared their amino acid sequences with those of mammalian EAATs and VGLUTs, we found that the functional domains of both types are well conserved. Third, in situ hybridization revealed that the mRNAs of LymEAAT and LymVGLUT are localized in large populations of nerve cells, including the major feeding motoneurons in the buccal ganglia. Finally, we inhibited LymEAAT and found that changes in the firing patterns of the feeding motoneurons that have GLUergic input were similar to those obtained following stimulation with GLU. Our results confirmed the presence of GLU uptake systems in the Lymnaea CNS and showed that LymEAAT is required for proper rhythm generation, particularly for generation of the feeding rhythm. (C) 2009 Wiley-Liss, Inc.

    DOI

  • Unilateral memory storage in the procerebrum of the terrestrial slug Limax

    Ryota Matsuo, Eri Kawaguchi, Miki Yamagishi, Tetsuo Amano, Etsuro Ito

    NEUROBIOLOGY OF LEARNING AND MEMORY   93 ( 3 ) 337 - 342  2010.03

     View Summary

    In most sensory modalities, neuronal inputs are bilaterally processed in a higher center. In some animal species, however, functional lateralization is sometimes observed in the sensory processing at the higher level. For the terrestrial slug Limax, olfaction is the most important sensory modality and this slug can acquire odor-aversion memories. Previously, it has been demonstrated in bilateral PC ablation experiments that the procerebrum (PC) is necessary for odor-aversion memory, and that the PC is the memory storage site. On the other hand, it has been hypothesized that only the unilateral PC is used for odor-aversion learning. Here we demonstrated that the number of the slugs with intact memory performance was reduced by approximately 50% when the PC was surgically ablated only unilaterally before or after conditioning. There was no difference in the memory performance of the right vs. the left PC-ablated slugs. However, memory deficit from unilateral PC ablation was not observed when the ipsilateral tentacles were also amputated at the same time. We also showed that there was no lateral memory transfer from one PC to the other, after up to 7 days post-conditioning. Our results demonstrated clearly that either the left or right PC is randomly used for olfactory learning, and that the side of use is determined at the level of the olfactory ascending pathway to the PC. (c) 2009 Elsevier Inc. All rights reserved.

    DOI PubMed

  • Contrary Effects of Octopamine Receptor Ligands on Behavioral and Neuronal Changes in Locomotion of Lymnaea

    Yurie Miyamae, Mami Komuro, Aya Murata, Kanako Aono, Kaori Nishikata, Akira Kanazawa, Yutaka Fujito, Takumi Komatsu, Daisuke Ito, Takashi Abe, Masafumi Nagayama, Tsutomu Uchida, Kazutoshi Gohara, Jun Murakami, Ryo Kawai, Dai Hatakeyama, Ken Lukowiak, Etsuro Ito

    BIOLOGICAL BULLETIN   218 ( 1 ) 6 - 14  2010.02

     View Summary

    The pond snail Lymnaea stagnalis moves along the sides and bottom of an aquarium, but it can also glide upside down on its back below the water&apos;s surface. We have termed these two forms of locomotion "standard locomotion" and "upside-down gliding," respectively. Previous studies showed that standard locomotion is produced by both cilia activity on the foot and peristaltic contraction of the foot muscles. whereas upside-down gliding is mainly caused by cilia activity. The pedal A neurons are thought to receive excitatory octopaminergic input, Which ultimately results in increased cilia beating. However, the relationship between locomotory speed and the responses of these neurons to octopamine is not known. We thus examined the effects of both an agonist and an antagonist of octopamine receptors on locomotory speed and the firing rate of the pedal A neurons. We also examined. at the electron and light-microscopic levels, whether structural changes occur in cilia following the application of either an agonist or an antagonist of octopamine receptors to the central nervous system (CNS). We found that the application of an octopamine antagonist to the CNS increased the speed of both forms of locomotion, whereas application of octopamine increased only the firing rate of the pedal A neurons. Microscopic examination of the cilia proved that there were no chan-e in their morphology after application of octopamine me ligands. These data suggest that there is an unidentified octopaminergic neuronal network in the CNS whose activation reduces cilia movement and thus locomotory speed.

    DOI

  • Spontaneous Recovery of the Injured Higher Olfactory Center in the Terrestrial Slug Limax

    Ryota Matsuo, Suguru Kobayashi, Jun Murakami, Etsuro Ito

    PLOS ONE   5 ( 2 ) e9054  2010.02

     View Summary

    Background: Of all organs and tissues in adult mammals, the brain shows the most limited regeneration and recovery after injury. This is one reason why treating neurological damage such as ischemic injury after stroke presents such a challenge. Here we report a novel mode of regeneration which the slug&apos;s cognitive center, the procerebrum, shows after surgical lesioning in the adult. It is well known that the land slug Limax possesses the capacity to demonstrate conditioned food aversion. This learning ability critically depends on the procerebrum, which is the higher olfactory center in the brain of the terrestrial mollusk.
    Principal Findings: In the present study, after a 1-month recovery period post-surgical lesioning of the procerebrum we investigated whether the brain of the slug shows recovery from damage. We found that learning ability, local field potential oscillation, and the number of cells in the procerebrum (PC) all recovered spontaneously within 1 month of bilateral lesioning of the PC. Moreover, neurogenesis was enhanced in the lesioned PC. However, memory acquired before the surgery could not be retrieved 1 month after surgery although the procerebrum had recovered from injury by this time, consistent with the notion that the procerebrum is the storage site of odor-aversion memory, or deeply involved in the memory recall process.
    Significance: Our findings are the first to demonstrate that a brain region responsible for the associative memory of an adult organism can spontaneously reconstitute itself, and can recover its function following injury.

    DOI

  • Opposing effects of FMRFamide and serotonin on oscillatory neuronal synchronization in slug olfactory center

    Suguru Kobayashi, Mariko Hattori, Ryota Matsuo, Etsuro Ito

    JOURNAL OF PHYSIOLOGICAL SCIENCES   60   S135 - S135  2010

    Research paper, summary (international conference)  

  • 数理モデルによるミツバチの8の字ダンスの生物的意義の解析

    岡田龍一, 池野英利, 木村敏文, 大橋瑞江, 青沼仁志, 伊藤悦朗

    日本比較生理生化学会大会予稿集   32nd   29  2010

    J-GLOBAL

  • ミツバチの採餌行動は尻振りダンス行動によって効率的になるのか?

    岡田龍一, 池野英利, 赤松忠明, 岩田可南子, 木村敏文, 大橋瑞江, 青沼仁志, 伊藤悦朗

    日本動物学会中国四国支部会報   ( 62 ) 12  2010

    J-GLOBAL

  • Learning-dependent gene expression of CREB1 isoforms in the molluscan brain

    Hisayo Sadamoto, Takashi Kitahashi, Yutaka Fujito, Etsuro Ito

    FRONTIERS IN BEHAVIORAL NEUROSCIENCE   4   25  2010

     View Summary

    Cyclic AMP-responsive element binding protein1 (CREB1) has multiple functions in gene regulation. Various studies have reported that CREB1-dependent gene induction is necessary for memory formation and long-lasting behavioral changes in both vertebrates and invertebrates. In the present study, we characterized Lymnaea CREB1 (LymCREB1) mRNA isoforms of spliced variants in the central nervous system (CNS) of the pond snail Lymnaea stagnalis. Among these spliced variants, the three isoforms that code a whole LymCREB1 protein are considered to be the activators for gene regulation. The other four isoforms, which code truncated LymCREB1 proteins with no kinase inducible domain, are the repressors. For a better understanding of the possible roles of different LymCREB1 isoforms, the expression level of these isoform mRNAs was investigated by a real-time quantitative RT-PCR method. Further, we examined the changes in gene expression for all the isoforms in the CNS after conditioned taste aversion (CTA) learning or backward conditioning as a control. The results showed that CTA learning increased LymCREB1 gene expression, but it did not change the activator/repressor ratio. Our findings showed that the repressor isoforms, as well as the activator ones, are expressed in large amounts in the CNS, and the gene expression of CREB1 isoforms appeared to be specific for the given stimulus. This was the first quantitative analysis of the expression patterns of CREB1 isoforms at the mRNA level and their association with learning behavior.

    DOI

  • Glutamatergic Neurotransmission in the Procerebrum (Olfactory Center) of a Terrestrial Mollusk

    Ryota Matsuo, Suguru Kobayashi, Satoshi Watanabe, Shigeyuki Namiki, Sho Iinuma, Hirokazu Sakamoto, Kenzo Hirose, Etsuro Ito

    JOURNAL OF NEUROSCIENCE RESEARCH   87 ( 13 ) 3011 - 3023  2009.10

     View Summary

    The terrestrial slug Limax has the ability to learn odor associations. This ability depends on the function of the procerebrum, the secondary olfactory center in the brain. Among the various neurotransmitters that are thought to be involved in the function of the procerebrum, glutamate is one of the most important molecules. However, the existence and function of glutamate in this system have been proposed solely on the basis of a few lines of indirect evidence from pharmacological experiments. In the present study, we demonstrated the existence and release of glutamate as a neurotransmitter in the procerebrum of Limax, by using three different techniques: 1) immunohistochemistry of glutamate, 2) in situ hybridization to mRNA of the vesicular glutamate transporter, and 3) real-time imaging of glutamate release within the procerebrum using the glutamate optical sensor EOS2. The release of glutamate within the cell mass layer of the procerebrum was synchronized with oscillation of the local field potential and had the same physiological properties as this oscillation; both were blocked by a serotonin antagonist and were propagated in an apical to basal direction in the procerebrum. Our observations suggest strongly that the oscillation of the local field potential is driven by the glutamate released by bursting neurons in the procerebrum. (C) 2009 wiley-Liss, Inc.

    DOI

  • A novel nitric oxide synthase expressed specifically in the olfactory center

    Ryota Matsuo, Etsuro Ito

    BIOCHEMICAL AND BIOPHYSICAL RESEARCH COMMUNICATIONS   386 ( 4 ) 724 - 728  2009.09

     View Summary

    Nitric oxide (NO) plays important roles in the olfactory center of various animals. In the terrestrial slug, NO is indispensable for field potential oscillation in the higher olfactory center, the procerebrum (PC), and also for odor learning. Here we identify a novel NO synthase (NOS) gene, limNOS2, in the terrestrial slug. The mRNA (similar to 10 kb) of limNOS2 encodes a protein consisting of 1616 amino acids, including a PDZ domain. The protein has 70.0% sequence identity with the previously identified limNOS1 gene. In contrast to limNOS1, however, limNOS2 is expressed specifically in the PC. Moreover, most of the cells in the PC contain limNOS2 mRNA, indicating that the nonbursting neurons, the major constituent of the PC, have this mRNA. The expression pattern of limNOS2 conforms well to the pattern of NOS enzymatic histochemical staining. Our present findings indicate that limNOS2 is responsible for most of the NO generation in the PC. (C) 2009 Elsevier Inc. All rights reserved.

    DOI PubMed CiNii

  • Effects of a waggle dance on the honeybee foraging behavior

    岡田龍一, 池野英利, 木村敏文, 大橋瑞江, 青沼仁志, 伊藤悦朗

    日本動物学会大会予稿集   80th (Web)  2009

    J-GLOBAL

  • The procerebrum of a terrestrial mollusk spontaneously regenerates via neurogenesis and restores its function following injury

    Ryota Matsuo, Suguru Kobayashi, Jun Murakami, Etsuro Ito

    NEUROSCIENCE RESEARCH   65   S49 - S49  2009

    Research paper, summary (international conference)  

    DOI

  • MODULATION OF OSCILLATORY NEURONAL SYNCHRONIZATION BY NEUROTRANSMITTER AND NEUROPEPTIDE IN SLUG OLFACTORY CENTER

    Suguru Kobayashi, Mariko Hattori, Ryota Matsuo, Etsuro Ito

    JOURNAL OF PHYSIOLOGICAL SCIENCES   59   140 - 140  2009

    Research paper, summary (international conference)  

  • グルタミン酸トランスポーターによるモノアラガイ咀嚼リズムの調節

    畠山大, 箕田康一, 小林卓, 定本久世, 伊藤悦朗

    日本比較生理生化学会大会予稿集   31st   68  2009

    J-GLOBAL

  • ミツバチの尻振りダンスとコロニーの集蜜量の関係

    岡田龍一, 赤松忠明, 岩田可南子, 池野英利, 木村敏文, 大橋瑞江, 青沼仁志, 伊藤悦朗

    日本比較生理生化学会大会予稿集   31st   69  2009

    J-GLOBAL

  • Gene expression of serotonin transporter after conditioned taste aversion learning in Lymnaea stagnalis

    Hisayo Sadamoto, Etsuro Ito

    COMPARATIVE BIOCHEMISTRY AND PHYSIOLOGY B-BIOCHEMISTRY & MOLECULAR BIOLOGY   151 ( 4 ) 450 - 450  2008.12

    Research paper, summary (international conference)  

    DOI

  • Upside-Down Gliding of Lymnaea

    Kanako Aono, Ayachika Fusada, Yorichika Fusada, Wataru Ishii, Yuji Kanaya, Mami Komuro, Kanae Matsui, Satoru Meguro, Ayumi Miyamae, Yurie Miyamae, Aya Murata, Shizuka Narita, Hiroe Nozaka, Wakana Saito, Ayumi Watanabe, Kaori Nishikata, Akira Kanazawa, Yutaka Fujito, Miki Yamagishi, Takashi Abe, Masafumi Nagayama, Tsutomu Uchida, Kazutoshi Gohara, Ken Lukowiak, Etsuro Ito

    BIOLOGICAL BULLETIN   215 ( 3 ) 272 - 279  2008.12

     View Summary

    The pond snail Lymnaea stagnalis can often be observed moving upside down on its back just below the surface of the water. We have termed this form of movement "upside-down gliding." To elucidate the mechanism of this locomotion, we performed a series of experiments involving behavioral analyses and microscopic observations. These experiments were designed (1) to measure the speed of this locomotion; (2) to determine whether the mucus secreted from the foot of Lymnaea repels water, thereby allowing the snail to exploit the surface tension of the water for upside-down gliding; and (3) to observe the beating of foot cilia in this behavior. The beating of these cilia is thought to be the primary driving force for upside-down gliding. Our results demonstrate that upside-down gliding is an efficient active process involving the secretion of mucus that floats up to the water surface to serve as a substrate upon which cilia beat to cause locomotion at the underside of the water surface.

    DOI

  • 巣内での追従バチの行動パターン

    岡田龍一, 池野英利, 木村敏文, 大橋瑞江, 青沼仁志, 伊藤悦朗

    日本動物学会大会予稿集   79th   132  2008.08

    J-GLOBAL

  • Atomic force microscopic observation of nucleosomes consisting of core histones and DNA promoter regions

    Akira Takashima, Hisayo Sadamoto, Akiko Okuta, Etsuro Ito

    INFORMATION-AN INTERNATIONAL INTERDISCIPLINARY JOURNAL   11 ( 4 ) 513 - 523  2008.07

     View Summary

    Atomic force microscopy (AFM) creates a topographic map of a sample surface and has enabled the imaging of biological surfaces. As an initial step in elucidating gene expression mechanisms from the perspective of structural biology, we have started to characterize the structure of nucleosomes that consist of core histones and DNA promoter regions, including specific transcription factor-related binding sites. We formed nucleosomes using core histones and tyrosine hydroxylase promoter regions that include cAMP- and TPA-responsive elements, and then we observed these nucleosomes using the dynamic-force (tapping) mode in AFM. Good correspondence was seen between the lengths of the DNA molecules observed by AFM and the theoretical values estimated from the base pairs of DNA molecules, thus confirming that the present AFM study acquired images of nucleosomes, including promoter regions.

  • Change of morphology and cytoskeletal protein gene expression during dibutyryl cAMP-induced differentiation in C6 glioma cells

    Weiwei Hu, Takeshi Onuma, Naoko Birukawa, Masashi Abe, Etsuro Ito, Zhong Chen, Akihisa Urano

    CELLULAR AND MOLECULAR NEUROBIOLOGY   28 ( 4 ) 519 - 528  2008.06

     View Summary

    Elevation of the intracellular cAMP level induces morphological changes of astrocyte-like differentiation in C6 glioma cells. Such changes may be accompanied with expression of cytoskeletal protein genes. We therefore analyzed morphological changes after a treatment with dibutyryl cAMP (dbcAMP) and then assessed the expression of cytoskeletal protein genes by a quantitative real-time polymerase chain reaction. The cell number remained unaltered upon incubation with 1 mM dbcAMP in medium supplemented with 0.1% fetal bovine serum (FBS), whereas the number and lengths of processes increased, when compared with those of cells incubated in medium supplemented with 0.1% or 10% FBS only. The amounts of beta-actin, gamma-actin, and beta-tubulin mRNAs in C6 cells, but not alpha-tubulin mRNA, increased during the early proliferation in DMEM containing 10% FBS. The expression of cytoskeletal protein genes decreased when incubated with 0.1% FBS or 1 mM dbcAMP in 0.1% FBS, compared with those of cells cultured in 10% FBS. These results indicated that, during the early proliferation in normal culture condition, the expression of cytoskeletal protein genes in C6 cells, except alpha-tubulin, increased, while in differentiating or differentiated C6 glioma cells, cAMP-induced morphological changes were not accompanied with elevation of gene expression for cytoskeletal proteins, such as actin and tubulin.

    DOI

  • Redundancy of olfactory sensory pathways for odor-aversion memory in the terrestrial slug Limax valentianus

    Miki Yamagishi, Etsuro Ito, Ryota Matsuo

    JOURNAL OF EXPERIMENTAL BIOLOGY   211 ( 12 ) 1841 - 1849  2008.06

     View Summary

    Terrestrial slugs have the ability to learn and remember a food odor paired with an aversive stimulus. Olfaction in slugs involves the tips of two pairs of tentacles, the superior and the inferior tentacles. Sensory nerves in both pairs of the tentacles transmit olfactory information to the structure in the CNS, the procerebrum where learning and memory formation occur. We investigated the role of each pair of tentacles in odor-aversion learning, and examined the ability of slugs to recall memory after selective surgical amputation. Our results show that memory formation was not altered by the amputation of either one of the pairs before or after odor-aversion learning, while the odor sensibility of the slugs was maintained. These data suggest that either pair of tentacles is sufficient for the acquisition and retrieval of aversive olfactory memory.

    DOI

  • A basic study of tracking honeybees in the observation hive using vector quantization method

    KIMURA Toshifumi, IKENO Hidetoshi, OHASHI Mizue, OKADA Ryuichi, ITO Etsuro

    IEICE technical report   107 ( 541 ) 113 - 116  2008.03

     View Summary

    The analysis of biological function produced by both of individual and assemblage activity of animals is a challenging topic of behavioral ecology. Social insects are possible tool for the analysis because numerous studies have been already done to clarify the behavioral factors of individuals. Especially, honeybee is an ideal animal for the experiments because of the development of breeding techniques, existence of clear caste according to their age, efficient forage behavior adaptive for variable feeding places and high ability of honey storage in their colony. Seeley et al. conducted many behavioral experiments in order to scrutinize honeybee behavior inside and outside of the nests. However, these experiments normally have to put numbers on each body of thousands of honeybees to identify individuals and follow their behavior by hand, which require huge time and labors. In this study, we developed a system to identify honeybee in a nest image and to follow plural honeybees simultaneously. The system is composed by three parts, determination of the region of honeybee body from the other parts with vector quantization, extraction of the region of single honeybee bodies, and reorganization of single honeybees. Our system succeeded to identify nearly 70% of honeybees in a hive automatically.

    CiNii

  • 巣内ミツバチ活動を評価するための時空間運動指標

    池野英利, 岡田龍一, 大橋瑞江, 木村敏文, 赤松忠明, 伊藤悦朗

    日本比較生理生化学会大会予稿集   30th  2008

    J-GLOBAL

  • ミツバチの観察巣板内行動追跡システム

    木村敏文, 池野英利, 大橋瑞江, 岡田龍一, 伊藤悦朗

    日本比較生理生化学会大会予稿集   30th  2008

    J-GLOBAL

  • 巣内ミツバチの歩行パターン

    岡田龍一, 池野英利, 木村敏文, 大橋瑞江, 青沼仁志, 伊藤悦朗

    日本比較生理生化学会大会予稿集   30th   29  2008

    J-GLOBAL

  • Biological Insights Into Robotics: Honeybee Foraging Behavior by a Waggle Dance

    Ryuichi Okada, Hidetoshi Ikeno, Hitoshi Aonuma, Etsuro Ito

    ADVANCED ROBOTICS   22 ( 15 ) 1665 - 1681  2008

     View Summary

    A honeybee informs her nestmates of flower locations by a unique behavior called a &apos;waggle dance&apos;. We regard this behavior as a good model of the &apos;propagation and sharing of knowledge&apos; to maintain a society. We have attempted to reveal how this dance benefits the colony using mathematical models and computer simulation based on parameters obtained from observations of bee behavior. Our simulation indicated that the most successful forages were made by a putative bee colony that used the dance to communicate. Video analysis of worker honeybee behavior in the field showed that a bee does not dance in a single, random place in the hive, but waggles several times in one place and several times in another. The orientation and duration of waggle runs varied from run to run, within ranges of +/- 15 degrees and +/- 15%, respectively. We also found that most of the bees that listened to the waggle dance turned away from the dancer after listening to one or two runs. These data suggest that honeybees use the waggle dance as a method of communication, but that they must base their forages oil ambiguous information about the location of a food source. (C) Koninklijke Brill NV, Leiden and The Robotics Society of Japan, 2008

    DOI CiNii

  • Genomic structure of nitric oxide synthase in the terrestrial slug is highly conserved

    Matsuo, R., Misawa, K., Ito, E.

    Gene   415 ( 1-2 ) 74 - 81  2008

    DOI PubMed CiNii

  • The dance of the honeybee: How do honeybees dance to transfer food information effectively?

    R. Okada, H. Ikeno, Noriko Sasayama, H. Aonuma, D. Kurabayashi, E. Ito

    ACTA BIOLOGICA HUNGARICA   59   157 - 162  2008

     View Summary

    A honeybee informs her nestmates of the location of a flower she has visited by a unique behavior called a "waggle dance." On a vertical comb, the direction of the waggle run relative to gravity indicates the direction to the food source relative to the sun in the field, and the duration of the waggle run indicates the distance to the food source. To determine the detailed biological features of the waggle dance, we observed worker honeybee behavior in the field. Video analysis showed that the bee does not dance in a single or random place in the hive but waggled several times in one place and then several times in another. It also showed that the information of the waggle dance contains a substantial margin of error. Angle and duration of waggle runs varied from run to run, with the range of +/- 15 degrees and +/- 15%, respectively, even in a series of waggle dances of a single individual. We also found that most dance followers that listen to the waggle (lance left the dancer after one or two sessions of listening.

    DOI

  • Speed of back-swimming of Lymnaea

    Kanako Aono, A. Fusada, Y. Fusada, W. Ishii, Y. Kanaya, Mami Komuro, Kanae Matsui, S. Meguro, Ayumi Miyamae, Yurie Miyamae, Aya Murata, Shizuka Narita, Hiroe Nozaka, Wakana Saito, Ayumi Watanabe, Kaori Nishikata, A. Kanazawa, Y. Fujito, R. Okada, K. Lukowiak, E. Ito

    ACTA BIOLOGICA HUNGARICA   59   105 - 109  2008

     View Summary

    The pond snail, Lymnaea stagnalis, can locomote on its back utilizing the surface tension of the water. We have called this form of movement 'back-swimming'. In order to perform this behavior, the snail must flip itself over on its back so that its foot is visible from above. Little is known about the mechanism of this back-swimming. As a first step for the elucidation of this mechanism, we measured the speed of back-swimming of Lymnaea at the different times of the day. They back-swam significantly faster in the morning than just before dark. These data are consistent with Our earlier findings on circadian-timed activity pattern in Lymnaea.. Lymnaea appear to secrete a thin membrane-like substance from their foot that may allow them to back-swim. To confirm the existence of this substance and to examine whether this substance is hydrophobic or hydrophilic, we applied a detergent onto the foot during back-swimming. A single drop of 1% Tween 20 drifted Lymnaea away that were still kept at the water surface. These results suggest that Lymnaea secrete a hydrophobic substance from their foot that floats to the water surface allowing Lymnaea to back-swim.

    DOI

  • The effects of GABA on the network oscillations of the procerebrum in Limax valentianus

    S. Kobayashi, Mariko Hattori, E. Ito

    ACTA BIOLOGICA HUNGARICA   59   77 - 79  2008

     View Summary

    Gamma-aminobutyric acid (GABA)-containing neurons are capable of controlling network oscillations and their patterns in the widely divergent species. In the terrestrial slug, Limax valentianus, oscillatory activity of the procerebrum neurons is considered to encode the odor information. Previous studies showed that GABA is present in the central nervous system and may be involved in the control of neuronal activity of Limax. In the present study, we examined the effects of GABA on the generation of oscillatory activity in the procerebrum. The results suggest that the GABAergic synaptic transmission may be involved in the oscillatory neural network of the procerebrum.

    DOI

  • Recovery of learning ability after the ablation of the procerebrum in the terrestrial slug, Limax valentianus

    R. Matsuo, E. Ito

    ACTA BIOLOGICA HUNGARICA   59   73 - 76  2008

     View Summary

    The procerebrum (PC) is indispensable for odor-aversion learning in Limax. On the other hand, the central nervous system (CNS) of some Pulmonata shows robustness against injury, recovering from nerve injury both at the histological and functional levels. To investigate whether the PC of Limax also shows robustness against nerve injury, we tested whether or not the slugs can acquire and retrieve odor-aversion memory after a long recovery period from PC ablation. When the recovery period is short (7 days), the PC-ablated slugs failed to avoid the conditioned odor. But when the recovery period is long (I month), the PC-ablated slugs successfully avoided the conditioned odor. These results indicate that the CNS including the PC can recover from injury at least at the functional level.

    DOI

  • Localization of serotonin transporter mRNA in the CNS of Lymnaea stagnalis

    Hisayo Sadamoto, Z. Serfozo, E. Ito

    ACTA BIOLOGICA HUNGARICA   59   61 - 64  2008

     View Summary

    The serotonin transporter, SERT, is reported as a key molecule that regulates serotonergic neurotransmission. In the present study, we analyzed the localization of Lymnaea SERT (LymSERT) mRNA-containing neurons by in situ hybridization using frozen sections of the central nervous system (CNS) of Lymnaea. To precisely demonstrate the distribution of LymSERT mRNA-containing neurons, colocalization with serotonin immunoreactivity was also examined. The results showed that LymSERT mRNA was constitutively expressed and localized in the serotonin-containing neurons in the CNS.

    DOI

  • 生物の社会適応機能の解明とその工学的応用 社会的適応行動から学ぶ情報共有システムの構築―ミツバチの8の字ダンスを対象として

    岡田龍一, 池野英利, 青沼仁志, 倉林大輔, 伊藤悦朗

    計測と制御   46 ( 12 ) 916 - 921  2007.12

    DOI CiNii J-GLOBAL

  • The gene expression of serotonin transporter after conditioned taste aversion learning in the CNS of Lymnaea stagnalis

    Hisayo Sadamoto, Etsuro Ito

    COMPARATIVE BIOCHEMISTRY AND PHYSIOLOGY B-BIOCHEMISTRY & MOLECULAR BIOLOGY   148 ( 3 ) 349 - 350  2007.11

    Research paper, summary (international conference)  

    DOI

  • Localization of glutamate-like immunoreactive neurons in the central and peripheral nervous system of the adult and developing pond snail, Lymnaea stagnalis

    Dai Hatakeyama, Hitoshi Aonuma, Etsuro Ito, Karoly Elekes

    BIOLOGICAL BULLETIN   213 ( 2 ) 172 - 186  2007.10

     View Summary

    We investigated the distribution and projection patterns of central and peripheral glutamate-like immunoreactive (GLU-LIR) neurons in the adult and developing nervous system of Lymnaea. Altogether, 50-60 GLU-LIR neurons are present in the adult central nervous system. GLU-LIR labeling is shown in the interganglionic bundle system and at the varicosities in neuropil of the central ganglia. In the periphery, the foot, lip, and tentacle contain numerous GLU-LIR bipolar sensory neurons. In the juvenile Lymnaea, GLU-LIR elements at the periphery display a pattern of distribution similar to that seen in adults, whereas labeled neurons increase in number in the different ganglia of the central nervous system from juvenile stage P1 up to adulthood. During embryogenesis, GLU-LIR innervation can be detected first at the 50% stage of embryonic development (the E50% stage) in the neuropil of the cerebral and pedal ganglia, followed by the emergence of labeled pedal nerve roots at the E75% stage. Before hatching, at the E90% stage, a few GLU-LIR sensory cells can be found in the caudal foot region. Our findings indicate a wide range of occurrence and a broad role for glutamate in the gastropod nervous system; hence they provide a basis for future studies on glutamatergic events in networks underlying different behaviors.

  • One-trial conditioning of aerial respiratory behaviour in Lymnaea stagnalis

    Kara Martens, Martin Amarell, Kashif Parvez, Karla Hittel, Pascaline De Caigny, Etsuro Ito, Ken Lukowiak

    NEUROBIOLOGY OF LEARNING AND MEMORY   88 ( 2 ) 232 - 242  2007.09

     View Summary

    Repeated spaced training sessions of contingent tactile stimulation to the pneumostome as it opens are required to cause long-term memory (LTM) formation of aerial respiratory behaviour making if difficult to determine exactly when memory forms. We have devised a single-trial aversive operant conditioning training procedure in Lymnaea to be better able to elucidate the causal mechanisms of LTM formation. Observations of baseline breathing behaviour in hypoxia were first made. Twenty-four hours later the snails were trained using the single trial procedure, by placing them in a small Petri dish containing 4 ml of 25 mM KCl for 30-35 s as soon as the first pneumostome opening in hypoxia was attempted. LTM was present if (1) breathing behaviour following training was significantly less than before; and (2) breathing behaviour post-training was significantly less in experimental groups than in yoked control groups. LTM persisted for 24 It but not 48 h. Yoked controls that received an aversive stimulus not contingent with pneumostome opening had no evidence of memory. Cooling directly after, but not at any other time, blocks LTM formation. LTM formation was also prevented by removal of the cell body of the neuron RPeD1 before training. (C) 2007 Elsevier Inc. All rights reserved.

    DOI PubMed

  • One-trial conditioned taste aversion in Lymnaea: good and poor performers in long-term memory acquisition

    Rio Sugai, Sachiyo Azami, Hatsuki Shiga, Takayuki Watanabe, Hisayo Sadamoto, Suguru Kobayashi, Dai Hatakeyama, Yutaka Fujito, Ken Lukowiak, Etsuro Ito

    JOURNAL OF EXPERIMENTAL BIOLOGY   210 ( 7 ) 1225 - 1237  2007.04

     View Summary

    In the majority of studies designed to elucidate the causal mechanisms of memory formation, certain members of the experimental cohort, even though subjected to exactly the same conditioning procedures, remember significantly better than others, whereas others show little or no long-term memory (LTM) formation. To begin to address the question of why this phenomenon occurs and thereby help clarify the causal mechanism of LTM formation, we used a conditioned taste aversion (CTA) procedure on individuals of the pond snail Lymnaea stagnalis and analyzed their subsequent behavior. Using sucrose as an appetitive stimulus and KCI as an aversive stimulus, we obtained a constant ratio of 'poor' to 'good' performers for CTA-LTM. We found that approximately 40% of trained snails possessed LTM following a one-trial conditioning procedure. When we examined the time-window necessary for the memory consolidation, we found that if we cooled snails to 4 degrees C for 30 min within 10 min after the one-trial conditioning, LTM was blocked. However, with delayed cooling (i.e. longer than 10 min), LTM was present. We could further interfere with LTM formation by inducing inhibitory learning (i.e. backward conditioning) after the one-trial conditioning. Finally, we examined whether we could motivate snails to acquire LTM by depriving them of food for 5 days before the one-trial conditioning. Food-deprived snails, however, failed to exhibit LTM following the one-trial conditioning. These results will help us begin to clarify why some individuals are better at learning and forming memory for specific tasks at the neuronal level.

    DOI

  • Gaseous neuromodulator-related genes expressed in the brain of honeybee Apis mellifera

    Takayuki Watanabe, Mika Kikuchi, Dai Hatakeyama, Takumi Shiga, Takehiro Yamamoto, Hitoshi Aonuma, Masakazu Takahata, Norio Suzuki, Etsuro Ito

    DEVELOPMENTAL NEUROBIOLOGY   67 ( 4 ) 456 - 473  2007.03

     View Summary

    Nitric oxide (NO), hydrogen sulfide (H2S), and carbon monoxide (CO) are thought to act as gaseous neuromodulators in the brain across species. For example, in the brain of honeybee Apis mellifera, NO plays important roles in olfactory learning and discrimination, but the existence of H2S- and CO-mediated signaling pathways remains unknown. In the present study, we identified the genes of nitric oxide synthase (NOS), soluble guanylyl cyclase (sGC), cystathionine beta-synthase (CBS), and heme oxygenase (HO) from the honeybee brain. The honeybee brain contains at least one gene for each of NOS, CBS, and HO. The deduced proteins for NOS, CBS, and HO are thought to contain domains to generate NO, H2S, and CO, respectively, and to contain putative Ca2+/calmodulinbinding domains. On the other hand, the honeybee brain contains three subunits of sGC: sGC alpha 1, sGC beta 1, and sGC beta 3. Phylogenetic analysis of sGC revealed that Apis sGC alpha 1 and sGC beta 1 are closely related to NO- and CO-sensitive sGC subunits, whereas Apis sGC beta 3 is closely related to insect O-2-sensitive sGC subunits. In addition, we performed in situ hybridization for Apis NOS mRNA and NADPH-diaphorase histochemistry in the honeybee brain. The NOS gene was strongly expressed in the optic lobes and in the Kenyon cells of the mushroom bodies. NOS activity was detected in the optic lobes, the mushroom bodies, the central body complex, the lateral protocerebral lobes, and the antennal lobes. These findings suggest that NO is involved in various brain functions and that H2S and CO can be endogenously produced in the honeybee brain. (c) 2007 Wiley Periodicals, Inc.

    DOI

  • The genomic structure and the variants of nitric oxide synthase gene in the terrestrial slug Limax valentianus

    Ryota Matsuo, Etsuro Ito

    NEUROSCIENCE RESEARCH   58   S138 - S138  2007

    Research paper, summary (international conference)  

  • Neuromodulatory effects of gonadotropin-releasing hormone on retinotectal synaptic transmission in the optic tecturn of rainbow trout

    Masae Kinoshita, Suguru Kobayashi, Akihisa Urano, Etsuro Ito

    EUROPEAN JOURNAL OF NEUROSCIENCE   25 ( 2 ) 480 - 484  2007.01

     View Summary

    Gonadotropin-releasing hormone (GnRH) is a hypophysiotropic decapeptide that stimulates the release of gonadotropins from the pituitary. In addition, there are extra-hypothalamic GnRH neurons that project to all regions of the brain and whose function remains unknown. Here, we investigated the effects of GnRH on retinotectal synaptic transmission, the synapses of which are formed between retinal fibers and tectal periventricular neurons that express GnRH receptor mRNA. We used rainbow trout as our study model. The excitatory postsynaptic currents (EPSCs), which were evoked by electrical stimulation of the retinal fibers and recorded in periventricular neurons, were suppressed by antagonists of ionotropic glutamate receptors. EPSCs were increased by application of each of two types of GnRH (GnRH2 and GnRH3) in the trout tectum. Such facilitation lasted for at least 10 min after application of the GnRH. To our knowledge, this is the first report of GnRH modulating conventional synaptic transmission in the brain, suggesting that tectal GnRH enhances tectal sensitivity for retinal inputs. Furthermore, such long-lasting facilitation might occur across all the brain regions innervated by GnRH neurons, and GnRH might simultaneously switch neuronal activities in the brain regions relevant to reproductive behaviors.

    DOI

  • Identification and expression analysis of rainbow trout pumilio-1 and pumilio-2

    Ikuo Kurisaki, Toshiharu Iwai, Masakane Yamashita, Miwako Kobayashi, Etsuro Ito, Ichiro Matsuoka

    CELL AND TISSUE RESEARCH   327 ( 1 ) 33 - 42  2007.01

     View Summary

    Pumilio is a sequence-specific RNA-binding protein that regulates translation from the relevant mRNA. The PUF-domain, the RNA-binding motif of Pumilio, is highly conserved across species. In the present study, we have identified two pumilio genes (pumilio-1 and pumilio-2) in rainbow trout and analyzed their expression patterns in its tissues. Pumilio-1 mRNA and pumilio-2A mRNA code for typical full length Pumilio proteins that contain a PUF-domain, whereas pumilio-2B mRNA is a splice variant of pumilio-2 and encodes a protein that lacks the PUF-domain. We have also identified a novel 72-bp exon that has not been reported in other animal species but is conserved in fish species. The insertion of this novel exon leads to the expression of an isoform of the Pumilio-2 protein with a slightly altered conformation of the PUF-domain. Pumilio-1 mRNA and pumilio-2A mRNA (irrespective of the presence of the 72-bp exon) are expressed in both the brain and ovaries at high levels, whereas pumilio-2B mRNA is expressed at low levels in all the rainbow trout tissues examined. Western blot analysis also indicates that the full length Pumilio proteins are expressed predominantly in the brain and ovaries. These data suggest that the Pumilio proteins have physiological roles and are involved in regulatory mechanisms in rainbow trout.

    DOI

  • The role of GABA in odor information processing in Limax varentianus

    Suguru Kobayashi, Ryota Matsuo, Etsuro Ito

    ZOOLOGICAL SCIENCE   23 ( 12 ) 1189 - 1189  2006.12

    Research paper, summary (international conference)  

  • Alteration of sert gene expression after taste aversion learning in the pond snail Lymnaea stagnalis

    Hisayo Sadamoto, Etsuro Ito

    ZOOLOGICAL SCIENCE   23 ( 12 ) 1203 - 1203  2006.12

    Research paper, summary (international conference)  

  • Genomic structure of nitric oxide synthase of the terrestrial slug Limax valentianus

    Ryota Matsuo, Etsuro Ito

    ZOOLOGICAL SCIENCE   23 ( 12 ) 1222 - 1222  2006.12

    Research paper, summary (international conference)  

  • Hsc70 ATPase: An insight into water dissociation and joint catalytic role of K+ and Mg2+ metal cations in the hydrolysis reaction

    Mauro Boero, Takashi Ikeda, Etsuro Ito, Kiyoyuki Terakura

    JOURNAL OF THE AMERICAN CHEMICAL SOCIETY   128 ( 51 ) 16798 - 16807  2006.12

     View Summary

    Hybrid quantum mechanics/molecular mechanics simulations, coupled to the recently introduced metadynamics method, performed on the adenosine triphosphate (ATP) of the bovine Hsc70 ATPase protein, show which specific water molecule of the solvation shell of the Mg2+ metal cation acts as a trigger in the initial phase of the ATP hydrolysis reaction in ATP synthase. Furthermore, we provide a detailed picture of the reaction mechanism, not accessible to experimental probes, that allows us to address two important issues not yet unraveled: (i) the pathway followed by a proton and a hydroxyl anion, produced upon dissociation of a putative catalytic H2O molecule, that is crucial in the selection of the reaction channel leading to the hydrolysis; (ii) the unique and cooperative role of K+ and Mg2+ metal ions in the reaction, acting as cocatalysts and promoting the release of the inorganic phosphate via an exchange of the OH- hydroxyl anion between their respective solvation shells. This is deeply different from the proton wire mechanism evidenced, for instance, in actin and lowers significantly the free energy barrier of the reaction.

    DOI PubMed CiNii

  • Periventricular efferent neurons in the optic tectum of rainbow trout

    Masae Kinoshita, Etsuro Ito, Akihisa Urano, Hironobu Ito, Naoyuki Yamamoto

    JOURNAL OF COMPARATIVE NEUROLOGY   499 ( 4 ) 546 - 564  2006.12

     View Summary

    The efferent connections and axonal and dendritic morphologies of periventricular neurons were examined in the optic tectum of rainbow trout to classify periventricular efferent neurons in salmonids. Among the target nuclei of tectal efferents, tracer injections to the following four structures labeled periventricular neurons: the area pretectalis pars dorsalis (APd), nucleus pretectalis superficialis pars magnocellularis (PSm), nucleus ventrolateralis of torus semicircularis (TS), and nucleus isthmi (NI). Two types of periventricular neurons were labeled by injections to the APd. One of them had an apical dendrite ramifying at the stratum fibrosum. et griseum. superficiale (SFGS), with an axon that bifurcated into two branches at the stratum griseum. centrale (SGC), and the other had an apical dendrite ramifying at the SGC. Two types of periventricular neurons were labeled after injections to the TS. One of them had an apical dendrite ramifying at the boundary between the stratum opticum (SO) and the SFGS, and the other had dendritic branches restricted to the stratum album centrale or stratum periventriculare. Injections to the PSm and NI labeled periventricular neurons of the same type with an apical dendrite ramifying at the SO and a characteristic axon that split into superficial and deep branches projecting to the PSm and NI, respectively. This cell type also possessed axonal branches that terminated within the tectum. These results indicate that periventricular efferent neurons can be classified into at least five types that possess type-specific axonal and dendritic morphologies. We also describe other tectal neurons labeled by the present injections.

    DOI

  • The learning-associated gene expression of serotonin transporter in Lymnaea stagnalis

    Hisayo Sadamoto, Etsuro Ito

    COMPARATIVE BIOCHEMISTRY AND PHYSIOLOGY B-BIOCHEMISTRY & MOLECULAR BIOLOGY   145 ( 3-4 ) 414 - 414  2006.11

    Research paper, summary (international conference)  

    DOI

  • Altered gene activity correlated with long-term memory formation of conditioned taste aversion in Lymnaea

    Sachiyo Azami, Akiko Wagatsuma, Hisayo Sadamoto, Dai Hatakeyama, Takeshi Usami, Manabu Fujie, Ryo Koyanagi, Kaoru Azumi, Yutaka Fujito, Ken Lukowiak, Etsuro Ito

    JOURNAL OF NEUROSCIENCE RESEARCH   84 ( 7 ) 1610 - 1620  2006.11

     View Summary

    The pond snail Lymnaea stagnalis is capable of learning conditioned taste aversion (CTA) and then consolidating that learning into long-term memory (LTM) that persists for at least 1 month. LTM requires cle novo protein synthesis and altered gene activity. Changes in gene activity in Lymnaea that are correlated with, much less causative, memory formation have not yet been identified. As a first step toward rectifying this situation, we constructed a cDNA microarray with mRNAs extracted from the central nervous system (CNS) of Lymnaea. We then, using this microarray assay, identified genes whose activity either increased or decreased following CTA memory consolidation. We also identified genes whose expression levels were altered after inhibition of the cyclic AMP response element-binding protein (CREB) that is hypothesized to be a key transcription factor for CTA memory. We found that the molluscan insulin-related peptide II (MIP II) was up-regulated during CTA-LTM, whereas the gene encoding pedal peptide preprohormone (Pep) was down-regulated by CRE132 RNA interference. We next examined mRNAs, of MIP II and Pep using real-time RT-PCR with SYBR Green. The MIP II mRNA level in the CNS of snails exhibiting "good" memory for CTA was confirmed to be significantly higher than that from the CNS of snails exhibiting.,poor" memory. In contrast, there was no significant difference in expression levels of the Pep mRNA between "good" and "poor" performers. These data suggest that in Lymnaea MIP II may play a role in the consolidation process that forms LTM following CTA training. (c) 2006 Wiley-Liss, Inc.

    DOI

  • De Novo synthesis of CREB in a presynaptic neuron is required for synaptic enhancement involved in memory consolidation

    Akiko Wagatsuma, Sachiyo Azami, Midori Sakura, Dai Hatakeyama, Hitoshi Aonuma, Etsuro Ito

    JOURNAL OF NEUROSCIENCE RESEARCH   84 ( 5 ) 954 - 960  2006.10

     View Summary

    Interaction between the activator type of cyclic AMP response element binding protein (CREB1) and the repressor type (CREB2) results in determining the emergence of long-lasting synaptic enhancement involved in memory consolidation. However, we still do not know whether the constitutively expressed forms of CREB are enough or the newly synthesized forms are required for the synaptic enhancement. In addition, if the newly synthesized forms are needed, we must determine the time for translation of CREB from its mRNA. We applied the methods of RNA interference and real-time polymerase chain reaction (PCR) to CREB in the cerebral giant cells of Lymnaea. The cerebral giant cells play an important role in associative learning and employ a CREB cascade for the synaptic enhancement to neurons such as the B1 moto-neurons. We injected the small interfering RNA (siRNA) of CREB1 or CREB2 into the cerebral giant cells and examined the changes in amplitude of excitatory postsynaptic potential (EPSP) recorded in the B1 motoneurons. The changes in the amounts of CREB1 and CREB2 mRNAs were also examined in the cerebral giant cells. The EPSP amplitude was suppressed 15 min after injection of CREB1 siRNA, whereas that was augmented 60 min after injection of CREB2 siRNA. In the latter case, the decrease in the amount of CREB2 mRNA was confirmed by real-time PCR. Our results showed that the de novo synthesized forms of CREB are required within tens of minutes for the synaptic enhancement in memory consolidation. (c) 2006 Wiley-Liss, Inc.

    DOI

  • Glutamate release from astrocytes is stimulated via the appearance of exocytosis during cyclic AMP-induced morphologic changes

    Hatsuki Shiga, Jun Murakami, Takashi Nagao, Motoki Tanaka, Koichi Kawahara, Ichiro Matsuoka, Etsuro Ito

    JOURNAL OF NEUROSCIENCE RESEARCH   84 ( 2 ) 338 - 347  2006.08

     View Summary

    Recent studies have shown that astrocytes release various transmitters including glutamate and thus directly affect synaptic neurotransmission. The mechanisms involved in the release of glutamate from astrocytes remain unclear, however. In the present study, we examined differences in 1) the amount of glutamate released, 2) the appearance of exocytosis, and 3) the expression of SNARE (soluble N-ethylmaleimide sensitive fusion protein attachment protein receptor) proteins between cyclic AMP-treated and non-treated astrocytes in culture. Extracellular glutamate was detected in the recording solution of cyclic AMP-treated astrocytes after stimulation with ATP by high-performance liquid chromatography and NADH imaging. Exocytosis, which was observed by FM1-43 imaging, appeared in cyclic AMP-treated astrocytes in a punctiform fashion, but not in non-treated cells, after stimulation with ATP and glutamate. Immunocytochemistry and Western blotting showed that the amount of SNARE proteins increased during cAMP-induced morphologic changes, and in particular, a v-SNARE, synaptobrevin, appeared as punctiform staining in the cytosol of cyclic AMP-treated astrocytes. These findings show that astrocytes acquire SNARE proteins during cyclic AMP-induced differentiation, and suggest that glutamate is released by exocytosis in cyclic AMP-treated astrocytes in response to ATP released from neighboring neurons and astrocytes. (c) 2006 Wiley-Liss, Inc.

    DOI

  • Super water-repellent surfaces with fractal structures and their potential application to biological studies

    Hu Yan, Hatsuki Shiga, Etsuro Ito, Toshiyuki Nakagaki, Seiji Takagi, Tetsuo Ueda, Kaoru Tsujii

    COLLOIDS AND SURFACES A-PHYSICOCHEMICAL AND ENGINEERING ASPECTS   284   490 - 494  2006.08

     View Summary

    Super water repellency of solid surfaces can be realized by formation of fractal structures, which were verified and explained by various materials, such as alkylketene dimer (AKD), platinum-palladium alloy-covered AKD, and poly(alkylpyrrole), and also by comparison of fractal surfaces with smooth ones. Novel potential applications of the fractal solid surfaces to unique biological studies are suggested based on our previous and the present biological studies on fractal AKD surfaces. (c) 2005 Elsevier B.V. All rights reserved.

    DOI

  • Roles of periventricular neurons in retinotectal transmission in the optic tectum

    Masae Kinoshita, Etsuro Ito

    PROGRESS IN NEUROBIOLOGY   79 ( 2 ) 112 - 121  2006.06

    Book review, literature introduction, etc.  

     View Summary

    The midbrain roof is a retinorecipient region referred to as the optic tectum in lower vertebrates, and the superior colliculus in mammals. The retinal fibers projecting to the tectum transmit visual information to tectal retinorecipient neurons. Periventricular neurons are a subtype of these neurons that have their somata in the deepest layer of the teleostean tectum and apical dendrites ramifying at more superficial layers consisting of retinal fibers. The retinotectal synapses between the retinal fibers and periventricular neurons are glutamatergic, and ionotropic glutamate receptors mediate the transmission in these synapses. This transmission involves long-term potentiation, and is modulated by hormone action. Visual information processed in the periventricular neurons is transmitted to adjacent tectal cells and target nuclei of periventricular neuron axonal branches, some of which relay the visual information to other brain areas controlling behavior. We demonstrated that periventricular neurons play a principal role in visual information processing in the teleostean optic tectum; the effects of tectal output on behavior is discussed also in the present review. (c) 2006 Elsevier Ltd. All rights reserved.

    DOI

  • Taste discrimination in conditioned taste aversion of the pond snail Lymnaea stagnalis

    R Sugai, H Shiga, S Azami, T Watanabe, H Sadamoto, Y Fujito, K Lukowiak, E Ito

    JOURNAL OF EXPERIMENTAL BIOLOGY   209 ( 5 ) 826 - 833  2006.03

     View Summary

    Conditioned taste aversion (CTA) in the pond snail Lymnaea stagnalis has been widely used as a model for gaining an understanding of the molecular and behavioral mechanisms underlying learning and memory. At the behavioral level, however, it is still unclear how taste discrimination and CTA interact. We thus examined how CTA to one taste affected the feeding response induced by another appetitive food stimulus. We first demonstrated that snails have the capacity to recognize sucrose and carrot juice as distinct appetitive stimuli. We then found that snails can become conditioned (i.e. CTA) to avoid one of the stimuli and not the other. These results show that snails can distinguish between appetitive stimuli during CTA, suggesting that taste discrimination is processed upstream of the site where memory consolidation in the snail brain occurs. Moreover, we examined second-order conditioning with two appetitive stimuli and one aversive stimulus. Snails acquired second-order conditioning and were still able to distinguish between the different stimuli. Finally, we repeatedly presented the conditional stimulus alone to the conditioned snails, but this procedure did not extinguish the long-term memory of CTA in the snails. Taken together, our data suggest that CTA causes specific, irreversible and rigid changes from appetitive stimuli to aversive ones in the conditioning procedure.

    DOI

  • Requirement of new protein synthesis of a transcription factor for memory consolidation: Paradoxical changes in mRNA and protein levels of C/EBP

    D Hatakeyama, H Sadamoto, T Watanabe, A Wagatsuma, S Kobayashi, Y Fujito, M Yamashita, M Sakakibara, G Kemenes, E Ito

    JOURNAL OF MOLECULAR BIOLOGY   356 ( 3 ) 569 - 577  2006.02

     View Summary

    Some specific transcription factors are essential for memory consolidation across species. However, it is still unclear whether only the activation of constitutively expressed forms of these conserved transcription factors is involved in memory consolidation or their de novo synthesis also occurs after learning. This question has remained unanswered partly because of the lack of an efficient method for the determination of copy numbers of particular mRNAs in single neurons, which allows the detection of new transcription at the cellular level. Here we applied a newly developed protocol of single-cell quantitative real-time polymerase chain reaction (qRT-PCR) to single neurons playing an important role in associative learning. Specifically, we examined the changes in the mRNA and protein expression levels of a highly conserved transcription factor, CCAAT/enhancer binding protein (C/EBP), in the paired B2 motoneurons of the pond snail Lymnaea stagnalis. These buccal neurons are involved in the motor control of feeding behavior, with a potentially important role in conditioned taste aversion (CTA). Single-cell qRT-PCR revealed a significant decrease in LymC/EBP mRNA copy numbers in the B2 motoneurons during memory consolidation after CTA training. By contrast, isoelectric focusing and immunoblotting of extracts of the buccal ganglia showed that translation and phosphorylation levels of LymC/EBP significantly increased during memory consolidation. The C/EBP-like immunoreactivity in the B2 motoneurons, which are the major immunopositive component in the buccal ganglia, also significantly increased during memory consolidation, suggesting that the main source of increase in the level of protein in the buccal ganglia are the B2 motoneurons. Thus, early memory consolidation after CTA learning in L. stagnalis involves both the rapid synthesis and phosphorylation of LymC/EBP as well as the rapid breakdown of LymC/EBP mRNA in the neural network controlling feeding, suggesting that all of these processes play a role in the function of C/EBP in memory consolidation. (c) 2005 Elsevier Ltd. All rights reserved.

    DOI PubMed CiNii

  • Immunohistological study on the distribution of calexcitin in the conditioned Lymnaea CNS

    Yasutaka Nomura, Dai Hatakeyama, Tetsuro Horikoshi, Etsuro Ito, Manabu Sakakibara

    NEUROSCIENCE RESEARCH   55   S96 - S96  2006

    Research paper, summary (international conference)  

  • 1個の細胞の中の1個のタンパク質の定量を目指して

    伊藤悦朗, 渡部聡, 伊藤敬三, 米山祐樹

    バイオテクノロジージャーナル   6 ( 5 ) 609 - 612  2006

    CiNii

  • Cell cultures on a super water-repellent alkylketene dimer surface

    Hu Yan, Hatsuki Shiga, Etsuro Ito, Kaoru Tsujii

    INTERNATIONAL JOURNAL OF NANOSCIENCE, VOL 5, NO 6   5 ( 6 ) 871 - +  2006

     View Summary

    The fractal alkylketene dimer (AKD) surface is an artificial super water-repellent one with a high contact angle of 174 degrees, therefore, may provide special surface circumstances for studies of biological cells such as cell cultures. The experimental results indicated that the distribution of F-actin in the astrocytes cultured on the fractal AKD-coated dishes showed the stellate shape, while that in the astrocytes cultured on the poly-L-lysine-coated coverslips showed the formation of long alignment. The morphological change of astrocytes is induced by the fractal AKD surface, and the result suggests that astrocyte differentiation is stimulated by the fractal AKD surface.

    DOI

  • Theoretical study of molecular recognition and activation mechanism of the glutamate receptor

    K.Odai, M.Kubo, E.Shiomitsu, T.Sugimoto, E.Ito

    Information   9   75 - 82  2006

  • Serotonin transporter in the CNS of the pond snail, Lymnaea stagnalis

    Hisayo Sadamoto, Etsuro Ito

    ZOOLOGICAL SCIENCE   22 ( 12 ) 1480 - 1480  2005.12

    Research paper, summary (international conference)  

  • Classification of periventricular neurons in the optic tectum of rainbow trout

    Masae Kinoshita, Etsuro Ito, Akihisa Urano, Hironobu Ito, Naoyuki Yamamoto

    ZOOLOGICAL SCIENCE   22 ( 12 ) 1483 - 1483  2005.12

    Research paper, summary (international conference)  

  • Advancement of differentiation of oligodendrocyte progenitor cells by a cascade including protein kinase A and cyclic AMP-response element binding protein

    H Shiga, H Asou, E Ito

    NEUROSCIENCE RESEARCH   53 ( 4 ) 436 - 441  2005.12

     View Summary

    A transcription factor, cyclic AMP-response element binding protein (CREB), which is phosphorylated by protein kinases (PKA and PKC), is known to be involved in the regulation of oligodendrocyte differentiation. However, it is still unclear whether protein kinase A (PKA) and protein kinase C (PKC) are used simultaneously or at different time points to phosphorylate CREB in oligodendrocytes and whether CREB phosphorylation advances oligodendrocyte differentiation or vise versa. Our previous experiments have shown that in the differentiation process from immature to mature cells, CREB phosphorylation depends on PKC activity and leads to the progression of differentiation. In order to gain a better understanding of the process of differentiation from progenitor to immature cells, we identified which protein kinase, i.e., PKA or PKC, regulates CREB phosphorylation and we determined whether CREB phosphorylation advances differentiation or the reverse. Our results showed that CREB phosphorylation is principally regulated by PKA activity in progenitor cells but not by PKC activity, and that this phosphorylation advances the differentiation of progenitor cells to immature cells in oligodendrocytes. (c) 2005 Elsevier Ireland Ltd and the Japan Neuroscience Society. All rights reserved.

    DOI PubMed CiNii

  • Determination of the exact copy numbers of particular mRNAs in a single cell by quantitative real-time RT-PCR

    A Wagatsuma, H Sadamoto, T Kitahashi, K Lukowiak, A Urano, E Ito

    JOURNAL OF EXPERIMENTAL BIOLOGY   208 ( 12 ) 2389 - 2398  2005.06

     View Summary

    Gene expression is differently regulated in every cell even though the cells are included in the same tissue. For this reason, we need to measure the amount of mRNAs in a single cell to understand transcription mechanism better. However, there are no accurate, rapid and appropriate methods to determine the exact copy numbers of particular mRNAs in a single cell. We therefore developed a procedure for isolating a single, identifiable cell and determining the exact copy numbers of mRNAs within it. We first isolated the cerebral giant cell of the pond snail Lymnaea stagnalis as this neuron plays a key role in the process of memory consolidation of a learned behavior brought about by associative learning of feeding behavior. We then determined the copy numbers of mRNAs for the cyclic AMP-responsive element binding proteins (CREBs). These transcription factors play an important role in memory formation across animal species. The protocol uses two techniques in concert with each other: a technique for isolating a single neuron with newly developed micromanipulators coupled to an assay of mRNAs by quantitative real-time reverse transcription-polymerase chain reaction (qRT-PCR). The molecular assay determined the mRNA copy numbers, each of which was compared with a standard curve prepared from cDNA solutions corresponding to the serially diluted solutions of Lymnaea CREB mRNA. The standard curves were linear within a range of 10 to 10(5) copies, and the intra-assay variation was within 15%. Each neuron removed from the ganglia was punctured to extract the total RNA directly and was used for the assay without further purification. Using this two-step procedure, we found that the mRNA copy number of CREB repressor (CREB2) was 30-240 in a single cerebral giant cell, whereas that of CREB activator (CREB1) was below the detection limits of the assay (&lt; 25). These results suggest that the CREB cascade is regulated by an excess amount of CREB2 in the cerebral giant cells. Our procedure is the only quantitative analysis for elucidation of the dynamics of gene transcription in a single cell.

    DOI

  • Differentiation of immature oligodendrocytes is regulated by phosphorylation of cyclic AMP-response element binding protein by a protein kinase C signaling cascade

    H Shiga, Y Yamane, M Kubo, Y Sakurai, H Asou, E Ito

    JOURNAL OF NEUROSCIENCE RESEARCH   80 ( 6 ) 767 - 776  2005.06

     View Summary

    Previous experiments showed that the expression and phosphorylation levels of cyclic AMP-response element binding protein (CREB) are important factors that regulate oligodendrocyte differentiation. The present study was designed to determine whether CREB phosphorylation advances oligodendrocyte differentiation or vice versa and to identify the protein kinase that primarily regulates CREB phosphorylation. We examined the expression and phosphorylation levels of CREB in developing oligodendrocytes at a specific differentiation stage by double-immunocytochemical staining with specific differentiation markers and antibody for phosphorylated CREB. We found that the CREB expression level increased along oligodendrocyte differentiation, and that its phosphorylated level was highest in immature oligodendrocytes. We also showed that CREB phosphorylation was regulated principally by protein kinase C (PKC) activity in immature oligodendrocytes. Our findings suggest that CREB phosphorylation is dependent on a PKC signaling cascade, and this phosphorylation activates CREB-mediated transcription and advances the differentiation of immature to mature oligodendrocytes. (c) 2005 Wiley-Liss, Inc.

    DOI

  • Retinotectal transmission in the optic tectum of rainbow trout

    M Kinoshita, M Fukaya, T Tojima, S Kojima, H Ando, M Watanabe, A Urano, E Ito

    JOURNAL OF COMPARATIVE NEUROLOGY   484 ( 2 ) 249 - 259  2005.04

     View Summary

    Retinotectal transmission has not yet been well characterized at the cellular level in the optic tectum. To address this issue, we used a teleost, the rainbow trout, and characterized periventricular neurons as postsynaptic cells expected to receive the retinotectal inputs to the optic tectum. The somata of periventricular neurons are localized in the upper zone of the stratum periventriculare (SPV), whereas the lower zone of the SPV comprises the cell body layer of radial glial cells. Ca2+ imaging identified functional ionotropic glutamate receptors in periventricular neurons. We also cloned cDNAs encoding the NR1 subunit of N-methyl-D-aspartic acid (NMDA) receptors and the GluR2 subunit of (+/-)-alpha-amino-3-hydroxy-5-methyl-isoxazole-4-propionic acid (AMPA) receptors, and detected their mRNAs in periventricular neurons by in situ hybridization. The presence of the receptor subunit proteins was also confirmed in the dendrites of periventricular neurons by immunoblotting and immunohistochemistry. On the other hand, radial glial cells in the lower zone of the SPV did not respond to glutamate applications, and mRNA and immunoreactivities of ionotropic glutamate receptors were not detected in glial cells. The present findings suggest that glutamatergic transmission at synapses between retinotectal afferents and periventricular neurons is mediated by the functional NMDA and AMPA receptors. (C) 2005 Wiley-Liss, Inc.

    DOI

  • セイヨウミツバチApis mellifera脳におけるガス神経伝達物質合成・受容酵素の遺伝子クローニングとその発現解析

    渡邊崇之, 菊池美香, 青沼仁志, 鈴木範男, 伊藤悦朗

    日本比較生理生化学会大会予稿集   27th   23  2005

    J-GLOBAL

  • Cellular mechanism of calcium signaling and gliotransmitter release of astrocytes

    H.Shiga, E.Ito

    Recent Research Developments in Biophysics   4   19 - 33  2005

  • Nitric oxide synthase and soluble guanylyl cyclase underlying the modulation of electrical oscillations in a central olfactory organ

    S Fujie, T Yamamoto, J Murakami, D Hatakeyama, H Shiga, N Suzuki, E Ito

    JOURNAL OF NEUROBIOLOGY   62 ( 1 ) 14 - 30  2005.01

     View Summary

    We have isolated and characterized the cDNAs for nitric oxide synthase (NOS) and soluble guanylyl cyclase (sGC) from the terrestrial slug Limax marginatus, and examined the presence and distribution of their mRNAs in the central nervous system using histological techniques and a reverse transcription-polymerase chain reaction method. Our results showed that both bursting and nonbursting neurons in the procerebral lobes contain the mRNAs for both NOS and sGC. We further found that the oscillation frequency of electrical activity in the procerebral lobes increases with increasing intracellular concentrations of cyclic GMP (cGMP). Taken together with previous data on the NO-induced cGMP-like immunoreactivity and on the anatomical distribution of neurites and the localization of synapses of bursting and nonbursting neurons, our present results suggest that NO-induced changes in cGMP concentration modulate the oscillation frequency in the procerebral lobes by acting on the olfactory input pathways, but possibly not on the output pathways, in Slugs. (C) 2004 Wiley Periodicals, Inc.

    DOI

  • Consolidation of long-term memory by one-trial CTA learning in Lymnaea

    Etsuro Ito, Rio Sugai, Sachiyo Azami

    ZOOLOGICAL SCIENCE   21 ( 12 ) 1322 - 1322  2004.12

    Research paper, summary (international conference)  

  • CREB isoforms in central nervous system of pond snail Lymnaea stagnalis

    Hisayo Sadamoto, Akiko Wagatsuma, Kenta Saito, Masataka Kinjo, Etsuro Ito

    ZOOLOGICAL SCIENCE   21 ( 12 ) 1317 - 1317  2004.12

    Research paper, summary (international conference)  

  • Tectal periventricular neurons projecting to the torus semicircularis in rainbow trout

    Masae Kinoshita, Etsuro Ito, Akihisa Urano, Hironobu Ito, Naoyuki Yamamoto

    ZOOLOGICAL SCIENCE   21 ( 12 ) 1315 - 1315  2004.12

    Research paper, summary (international conference)  

  • Expression and distribution of transcription factor CCAAT/enhancer-binding protein in the central nervous system of Lymnaea stagnalis

    D Hatakeyama, Y Fujito, M Sakakibara, E Ito

    CELL AND TISSUE RESEARCH   318 ( 3 ) 631 - 641  2004.12

     View Summary

    The transcription factor, CCAAT/enhancer-binding protein (C/EBP), is involved in important physiological processes, such as cellular proliferation and differentiation, homeostasis, and higher-order functions of the brain. In the present study, we investigated the distribution of mRNA and protein of C/EBP in the central nervous system of the pond snail, Lymnaea stagnalis, by in situ hybridization and immunohistochemistry. Specificity of the anti-mammalian C/EBP antibody against Lymnaea C/EBP (LymC/EBP) was confirmed by combination of sodium dodecyl sulfate polyacrylamide gel electrophoresis or isoelectric focusing and immunoblotting. Cells positive for in situ hybridization were immunoreactive for LymC/EBP in all 11 ganglia. The motoneurons (B1, B2, B4, and B4 clusters) in the buccal ganglia and interneurons ( cerebral giant cell, CGC) in the cerebral ganglia were positive for in situ hybridization and were immunopositive. In the pedal ganglion, the right pedal dorsal 1 (RPeD1), pedal A, and pedal C clusters exhibited positive signals of in situ hybridization and immunohistochemistry for LymC/EBP. CGC and RPeD1 are key neurons for associative learning. In addition, the neuropeptidergic cells in the cerebral, pleural, parietal, and visceral ganglia were positive for in situ hybridization and immunoreactive. Interestingly, although the cytoplasm of almost all immunopositive cells was stained, some neuropeptidergic cells located in the light parietal and visceral ganglia exhibited immunoreactivity in nuclei. Our results suggest that LymC/EBP is involved in learning and memory and in the expression and/or secretion of neuropeptides in Lymnaea.

    DOI

  • Long-term potentiation in the optic tectum of rainbow trout

    M Kinoshita, T Hosokawa, A Urano, Etsuro, I

    NEUROSCIENCE LETTERS   370 ( 2-3 ) 146 - 150  2004.11

     View Summary

    We examined synaptic plasticity in the optic tectum of rainbow trout by extracellular recordings. We found that the field-excitatory postsynaptic potential in the retinotectal synapses was potentiated by repetitive stimuli of 1.0 Hz for 20 s to the retinotectal afferents. The long-term potentiation (LTP) developed slowly, and was maintained for at least 2 h. Applications of an antagonist for N-methyl-D-aspartic acid (NMDA) receptors or Mg2+-free saline showed that activation of NMDA receptors was required to form the UP beyond the induction period. The present findings indicate that presynaptic stimulation in the retinotectal synapses causes LTP mediated by NMDA receptors in the optic tectum of rainbow trout. (C) 2004 Elsevier Ireland Ltd. All rights reserved.

    DOI

  • Structural dynamics of an ionotropic glutamate receptor

    M Kubo, E Ito

    PROTEINS-STRUCTURE FUNCTION AND BIOINFORMATICS   56 ( 3 ) 411 - 419  2004.08

    Book review, literature introduction, etc.  

     View Summary

    Ionotropic glutamate receptors (iGluRs) are postsynaptic ion channels involved in excitatory neurotransmission. iGluRs play important roles in development and in forms of synaptic plasticity that underlie higher order processes such as learning and memory. Neurobiological and biochemical studies have long characterized iGluRs in detail. However, the structural basis for the function of iGluRs has not yet been investigated, because there is insufficient information about their three-dimensional structures. In 1998, a crystal structure called S1S2 lobes was first solved for the extracellular bilobed ligand-binding domain of the GluR2 subunit. Since then, the crystal structures for the S1S2 lobes both in the apo and in various liganded states have been reported, and recent biophysical studies have further elucidated the dynamic aspects of the structure of the S1S2 lobes. In this review, the dynamic structures of the S1S2 lobes and their ligands are summarized, and the importance of their structural flexibility and fluctuation is discussed in light of the mechanisms of ligand recognition, activation, and desensitization of the receptor. (C) 2004 Wiley-Liss, Inc.

    DOI

  • Calexcitin-like immunoreactivity in the pond snail Lymnaea stagnalis

    D Hatakeyama, S Inamura, E Ito, M Sakakibara, TJ Nelson, DL Alkon

    NEUROSCIENCE RESEARCH COMMUNICATIONS   35 ( 1 ) 32 - 40  2004.07

     View Summary

    Calexcitin (CE) is a low molecular weight Ca2+- and guanosine triphosphate- binding protein, which is phosphorylated during associative learning in both vertebrates and invertebrates. The purpose of this study was to determine the presence of CE in the central nervous system (CNS) of the pond snail Lymnaea stagnalis, which can acquire classical and operant conditioning. Immunoblotting of CE showed that the anti-CE antibody prepared from squid can detect Lymnaea CE. In the cerebral ganglia, CE-like immunoreactivity was exhibited in two pairs of cell clusters that receive taste signals from the superior or median lip nerves. In both pedal ganglia, CE-like immunoreactivity was detected in 1-4 cell of the PeA clusters, which are involved in the withdrawal response. Our results therefore showed that CE is involved in the feeding and withdrawal neural networks, suggesting that CE may function in associative learning of feeding and withdrawal behavior in L. stagnalis.

    DOI

  • Initiation of functional synapses is associated with AMPA receptor expression

    K Chono, H Shiga, T Tojima, E Ito

    NEUROSCIENCE RESEARCH COMMUNICATIONS   35 ( 1 ) 24 - 31  2004.07

     View Summary

    In the present study, we identified the key protein that modulates the initiation of functional glutamatergic synapses in developing cortical neurons. First, we found a day in vitro that marked a critical increase in the number of functional synapses by the application of cyclic AMP, as demonstrated with Ca2+ imaging. We then examined the changes in the expression levels of proteins, which were expected to play a role in glutamatergic synapses, by the application of cyclic AMP. Our findings suggest that the expression of the alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid (AMPA) receptors modulates the initiation of functional synapses in developing neurons, and that immature neurons already contain N-methyl D-aspartate (NMDA) receptors and presynaptic proteins such as synaptophysin.

    DOI

  • Modulation of two oscillatory networks in the peripheral olfactory system by gamma-aminobutyric acid, glutamate, and acetylcholine in the terrestrial slug Limax marginatus

    Ito, I, T Kimura, S Watanabe, Y Kirino, E Ito

    JOURNAL OF NEUROBIOLOGY   59 ( 3 ) 304 - 318  2004.06

     View Summary

    The digit-like extensions (the digits) of the tentacular ganglion of the terrestrial slug Limax marginatus are the cell body rich region in the primary olfactory system, and they contain primary olfactory neurons and projection neurons that send their axons to the olfactory center via the tentacular nerves. Two cell clusters (the cell masses) at the bases of the digits form the other cell body rich regions. Although the spontaneous slow oscillations and odor responses in the tentacular nerve have been studied, the origin of the oscillatory activity is unknown. In the present study, we examined the contribution of the neurons in the digits and cell masses to generation of the tentacular nerve oscillations by surgical removal from the whole tentacle preparations. Both structures contributed to the tentacular oscillations, and surgical isolation of the digits from the whole tentacle preparations still showed spontaneous oscillations. To analyze the dynamics of odor-processing circuits in the digits and tentacular ganglia, we studied the effects of gamma-aminobutyric acid, glutamate, and acetylcholine on the circuit dynamics of the oscillatory network(s) in the peripheral olfactory system. Bath or local puff application of gamma-aminobutyric acid to the cell masses decreased the tentacular nerve oscillations, whereas the bath or local puff application of glutamate and acetylcholine to the digits increased the digits' oscillations. Our results suggest the existence of two intrinsic oscillatory circuits that respond differentially to endogenous neurotransmitters in the primary olfactory system of slugs. (C) 2004 Wiley Periodicals, Inc.

    DOI

  • CREB in the pond snail Lymnaea stagnalis: Cloning, gene expression, and function in identifiable neurons of the central nervous system

    H Sadamoto, H Sato, S Kobayashi, J Murakami, H Aonuma, H Ando, Y Fujito, K Hamano, M Awaji, K Lukowiak, A Urano, E Ito

    JOURNAL OF NEUROBIOLOGY   58 ( 4 ) 455 - 466  2004.03

     View Summary

    The pond snail Lymnaea stagnalis is an excellent model system in which to study the neuronal and molecular substrates of associative learning and its consolidation into long-term memory. Until now, the presence of cyclic AMP (cAMP)-responsive element binding protein (CREB), which is believed to be a necessary component in the process of a learned behavior that is consolidated into long-term memory, has only been assumed in Lymnaea neurons. We therefore cloned and analyzed the cDNA sequences of homologues of CREB1 and CREB2 and determined the presence of these mRNAs in identifiable neurons of the central nervous system (CNS) of L stagnalis. The deduced amino acid sequence of Lymnaea CREB1 is homologous to transcriptional activators, mammalian CREB1 and Aplysia CREB1a, in the C-terminal DNA binding (bZIP) and phosphorylation domains, whereas the deduced amino acid sequence of Lymnaea CREB2 is homologous to transcriptional repressors, human CREB2, mouse activating transcription factor-4, and Aplysia CREB2 in the bZIP domain. In situ hybridization revealed that only a relatively few neurons showed strongly positive signals for Lymnaea CREB1 mRNA, whereas all the neurons in the CNS contained Lymnaea CREB2 mRNA. Using one of the neurons (the cerebral giant cell) containing Lymnaea CREB1 mRNA, we showed that the injection of a CRE oligonucleotide inhibited a cAMP-induced, long-lasting synaptic plasticity. We therefore conclude that CREBs are present in Lymnaea neurons and may function as necessary players in behavioral plasticity. (C) 2003 Wiley Periodicals, Inc.

    DOI

  • Signal transduction cascades underlying de novo protein synthesis required for neuronal morphogenesis in differentiating neurons

    T Tojima, E Ito

    PROGRESS IN NEUROBIOLOGY   72 ( 3 ) 183 - 193  2004.02

    Book review, literature introduction, etc.  

     View Summary

    Differentiating neurons must acquire many unique morphological and functional characteristics in creating the precise neural circuits of the mature nervous system. The phenomenon of 'neuronal differentiation' includes a special set of simple, separate processes, that is, neuritogenesis, neurite outgrowth, pathfinding, targeting and synaptogenesis. All of these processes are critically dependent on the reorganization of actin cytoskeleton by many actin-binding proteins that function downstream of Rho-family GTPases. Furthermore, de novo synthesis of key proteins are critically involved in the reorganization of actin cytoskeleton during neuronal differentiation. In this article, we review recent progresses in the general mechanisms that control actin dynamics by various actin-binding proteins in differentiating neurons, including a series of recent studies from our laboratory on de novo synthesis of several key proteins that are essential for actin reorganization induced by second messengers. We demonstrated that dual regulation of cyclic AMP and Ca2+ determines cofilin (an actin-binding protein) phosphorylation states and LIM kinase 1 (a colifin kinase) expression level during neuritogenesis. (C) 2004 Elsevier Ltd. All rights reserved.

    DOI

  • Picosecond dynamics of the glutamate receptor in response to agonist-induced vibrational excitation

    M Kubo, E Shiomitsu, K Odai, T Sugimoto, H Suzuki, E Ito

    PROTEINS-STRUCTURE FUNCTION AND GENETICS   54 ( 2 ) 231 - 236  2004.02

     View Summary

    Conformational changes of proteins are dominated by the excitation and relaxation processes of their vibrational states. To elucidate the mechanism of receptor activation, the conformation dynamics of receptors must be analyzed in response to agonist-induced vibrational excitation. In this study, we chose the bending vibrational mode,of the guanidinium group of Arg485 of the glutamate receptor subunit GluR2 based on our previous studies, and we investigated picosecond dynamics of the glutamate receptor caused by the vibrational excitation of Arg485 via molecular dynamics simulations. The vibrational excitation energy in Arg485 in the ligand-binding site initially flowed into Lys730, and then into the J-helix at the subunit interface of the ligand-binding domain. Consequently, the atomic displacement in the subunit interface around an intersubunit hydrogen bond was evoked in about 3 ps. This atomic displacement may perturb the subunit packing of the receptor, triggering receptor activation.

    DOI

  • Involvement of actin filaments in intracellular and intercellular calcium signaling in astrocytes

    Trends Comp. Biochem. Physiol.   10   49 - 53  2004

  • The expression pattern of CREB genes in the central nervous system of the pond snail Lymnaea stagnalis

    Hisayo Sadamoto, Sachiyo Azami, E. Ito

    Acta Biologica Hungarica   55 ( 1-4 ) 163 - 166  2004

     View Summary

    To analyze the expression pattern of genes of cAMP responsive element binding protein (CREB), we performed in situ hybridization for the whole central nervous system (CNS) of the pond snail Lymnaea stagnalis. The CREB1 (activator) and CREB2 (repressor) homologues have already been cloned in L. stagnalis, and they are referred to as LymCREB1 and LymCREB2. Using the frozen sections and the whole mount preparations of the CNS, we mapped the distribution of LymCREB1 and LymCREB2 mRNA containing neurons. The present findings showed that the LymCREB1 mRNA containing neurons are a relatively few, whereas LymCREB2 mRNA is contained ubiquitously in the whole CNS of L. stagnalis.

    DOI PubMed

  • Real-time quantitative RT-PCR method for estimation of mRNA level of CCAAT/enhancer binding protein in the central nervous system of Lymnaea stagnalis

    D Hatakeyama, H Sadamoto, E Ito

    ACTA BIOLOGICA HUNGARICA   55 ( 1-4 ) 157 - 161  2004

     View Summary

    The fluorescence-based real-time reverse transcription polymerase chain reaction (RT-PCR) is becoming widely used to quantity mRNA level in cells and tissues and is now a crucial tool for basic biological researches and biotechnology. In the present study, on the basis of the real-time quantitative RT-RCR, we detected and quantified mRNA copies of the transcription factor, CCAAT/enhancer binding protein (C/EBP; an immediate-early gene that is involved in synaptic plasticity and teaming and memory) in the central nervous system of the pond snail Lymnaea stagnalis. We designed the primer set and the probe in the specific insert for the detection of Lymnaea C/EBP (LymC/EBP) clone 1. This insert is not contained in LymC/EBP clone 2 by alternative splicing. The copy number of LymC/EBP clone I was linearly decreased relative to the dilution of cDNA, and it was estimated 30 copies/mu1 in test sample. The availability of the present study showed that the real-time quantitative RT-PCR technique is more accurate and more specific for the detection and quantification of the mRNA level of genes in L. stagnalis than the other PCR methods.

    DOI

  • The early snail acquires the learning. Comparison of scores for conditioned taste aversion between morning and afternoon

    A Wagatsuma, R Sugai, K Chono, S Azami, D Hatakeyama, F Sadamoto, E Ito

    ACTA BIOLOGICA HUNGARICA   55 ( 1-4 ) 149 - 155  2004

     View Summary

    The pond snail Lymnaea stagnalis acquires conditioned taste aversion (CTA) and maintains its memory for more than a month. Snails in our laboratory were cultured at 20 degreesC on a 12: 12 light-dark cycle (light from 7 am to 7 pm). To examine the hours during which snails acquire CTA effectively, we trained some snails in the morning and others in the afternoon, and then compared their scores. CTA developed in both cases, but scores were significantly better in the morning than in the afternoon. To elucidate the cause of this difference in scores, we observed the voluntary activity of snails and found the circadian rhythm reflected in the snails' free-movement distances; distances at the circadian time 0-12 (daytime) were significantly longer than those at the circadian time 12-24 (nighttime). This rhythm was kept up for at least 3 days, even in constant darkness. In conclusion, L. stagnalis should be trained in the morning to acquire associative learning, possibly because of its greater propensity to roam about at that time as opposed to the afternoon.

    DOI

  • Distributions of gamma-aminobutyric acid immunoreactive and acetylcholinesterase-containing cells in the primary olfactory system in the terrestrial slug Limax marginatus

    Ito, I, S Watanabe, T Kimura, Y Kirino, E Ito

    ZOOLOGICAL SCIENCE   20 ( 11 ) 1337 - 1346  2003.11

     View Summary

    The tentacular ganglion, the primary olfactory system of terrestrial slugs, exhibits spontaneous oscillations with a spatial coherence. The digit-like extensions (digits) of the tentacular ganglion presumably house the cell bodies of the neurons underlying the oscillations. The present study was designed to identify the anatomical and physiological determinants of these oscillations with a special focus on whether the neurons located in the digits contribute to the coherent oscillations. We recorded field potentials from the spatially separated sites in the digits in the terrestrial slug Limax marginatus. We also simultaneously recorded tentacular nerve to monitor the coherent oscillations. The spatially separated regions in the digits oscillated at the same frequency as the tentacular nerve, indicating a single coherent activity. To study the neural networks underlying the coherent oscillations, we examined the distributions of acetylcholinesterase (AChE)-containing and gamma-aminobutyric acid immunoreactive (GABA-ir) neurons. AChE-containing and GABA-ir fibers were found to connect the neurons in a branch of the digits with those in other branches. We also used a vital staining technique with 1,1&apos;-didodecyl-3,3,3&apos;,3&apos;-tetramethylindocarbocyanine perchlorate to examine the projections of neurons in the digits. Large stained cells were detected in many branches of the digits after placing the dye on one of the cell masses located in right and left sides of the tentacular ganglion. They were detected in the cell masses and in many branches of the digits after placing the dye on a branch of the digits. Our results showed that the slug primary olfactory system has highly interconnected neural networks.

    DOI PubMed CiNii

  • Negative relationship between odor-induced spike activity and spontaneous oscillations in the primary olfactory system of the terrestrial slug Limax marginatus

    Ito, I, S Watanabe, T Kimura, Y Kirino, E Ito

    ZOOLOGICAL SCIENCE   20 ( 11 ) 1327 - 1335  2003.11

     View Summary

    Although primary olfactory systems in various animals display spontaneous oscillatory activity, its functional significance in olfactory processing has not been elucidated. The tentacular ganglion, the primary olfactory system of the terrestrial slug Limax marginatus, also displays spontaneous oscillatory activity at 1-2 Hz. In the present study, we examined the relationship between odor-evoked spike activity and spontaneous field potential oscillations in the tentacular nerve, representing the pathway from the primary olfactory system to the olfactory center. Neural activity was recorded from the tentacular nerve before, during and after application of various odors (garlic, carrot, and rat chow) to the sensory epithelium and the changes in firing rate and spontaneous oscillations were analyzed. We detected the baseline amplitude of the oscillations and baseline spike activity before stimulation. Odor stimulations for 20 s or 60 s evoked a transient increase in the firing rate followed by a decrease in the amplitude of spontaneous oscillations. The decrease in the amplitude was larger in the first 8 s of stimulation and subsequently showed recovery during stimulation. The amplitude of the recovered oscillations often fluctuated. Odor-evoked spikes appeared when the amplitude of the recovered oscillations was transiently small. These results suggest that the large oscillations could inhibit spike activity whereas the first transient increase in spike activity was followed by the decrease in the oscillation amplitude. Our results indicate that there is a significant negative correlation between spontaneous oscillations and odor-evoked spike activity, suggesting that the spontaneous oscillations contribute to the olfactory processing in slugs.

    DOI PubMed CiNii

  • Agonist-specific vibrational excitation of glutamate receptor

    M Kubo, E Shiomitsu, K Odai, T Sugimoto, H Suzuki, E Ito

    JOURNAL OF MOLECULAR STRUCTURE-THEOCHEM   639   117 - 128  2003.11

     View Summary

    Conformational changes of receptors are dominated by the excitation of their collective motions. The most likely energy source of this excitation is considered to be a collision of an agonist with the binding site of a receptor and a consequential excitation of their vibrational modes. In the present study, as an approach to elucidating the mechanism for receptor activation, we chose both the symmetric stretching vibration of the 1C-carboxyl group of glutamate and the bending vibration of the guanidinium group of Arg485 of the glutamate receptor subunit GluR2 based on our previous study, and we quantum-mechanically calculated the vibrational excitation probability of these two vibrations by glutamate collision. The excitation probability of these two vibrations was found to exceed 0.5 about 260 fs after the onset of collision within the first-order perturbation approximation. Taking into account that the period of these vibrations is about 20 fs, we can expect that the vibrational excitation occurs in Arg485 after tens of vibrations during the collision. This vibrational energy may redistribute to the collective motions of the receptor, resulting in global conformational changes in the receptor. We also confirmed that the charge transfer was small between an agonist and the binding site of GluR2. The glutamate receptor may be oscillatory systems that require the energy injection into the specific vibrational modes of the specific amino acid residues to trigger their activation. Such an injection of energy is provided by agonist collision. (C) 2003 Elsevier B.V. All rights reserved.

    DOI

  • A cell model study of calcium influx mechanism regulated by calciumdependent potassium channels in Purkinje cell dendrites

    K Chono, H Takagi, S Koyama, H Suzuki, E Ito

    JOURNAL OF NEUROSCIENCE METHODS   129 ( 2 ) 115 - 127  2003.10

     View Summary

    The present study was designed to elucidate the roles of dendritic voltage-gated K+ channels in Ca2+ influx mechanism of a rat Purkinje cell using a computer simulation program. First, we improved the channel descriptions and the maximum conductance in the Purkinje cell model to mimic both the kinetics of ion channels and the Ca2+ spikes, which had failed in previous studies. Our cell model is, therefore, much more authentic than those in previous studies. Second, synaptic inputs that mimic stimulation of parallel fibers and induce sub-threshold excitability were simultaneously applied to the spiny dendrites. As a result, transient Ca2+ responses were observed in the stimulation points and they decreased with the faster decay rate in the cell model including high-threshold Ca2+-dependent K+ channels than in those excluding these channels. Third, when a single synaptic input was applied into a spiny dendrite, Ca2+-dependent K+ channels suppressed Ca2+ increases at stimulation and recording points. Finally, Ca2+-dependent K+ channels were also found to suppress the time to peak Ca2+ values in the recording points. These results suggest that the opening of Ca2+-dependent K+ channels by Ca2+ influx through voltage-gated Ca2+ channels hyperpolarizes the membrane potentials and deactivates these Ca2+ channels in a negative feedback manner, resulting in local, weak Ca2+ responses in spiny dendrites of Purkinje cells. (C) 2003 Elsevier B.V. All rights reserved.

    DOI

  • Dual regulation of LIM kinase 1 expression by cyclic AMP and calcium determines cofilin phosphorylation states during neuritogenesis in NG108-15 cells

    T Tojima, M Takahashi, E Ito

    BRAIN RESEARCH   985 ( 1 ) 43 - 55  2003.09

     View Summary

    The present study was designed to elucidate the cellular and molecular mechanisms of neuritogenesis in differentiating neurons. For this purpose. we used pharmacological and immunochemical techniques to determine the intracellular signal transduction pathways that regulate actin dynamics during neuritogenesis. We confirmed that a rise in intracellular cyclic AMP (cAMP) concentration stimulated cells to increase their neurite numbers, and that this increase of neurites was suppressed by activation of calcineurin induced by a Ca2+ influx through voltage-dependent Ca2+ channels. Expression of a specific cofilin kinase (LIM kinase 1) was increased and decreased by cAMP and Ca2+ cascades. respectively. The phosphorylation state, but not the level of expression, of a potent regulator of actin dynamics (cofilin) was strongly correlated with the expression level of LIM kinase 1. Our results suggest that polymerization and depolymerization of actin by cofilin phosphorylation is necessary for neuritogenesis in differentiating neurons. (C) 2003 Elsevier B.V. All rights reserved.

    DOI

  • Quantum chemical study of ligand-receptor electrostatic interactions in molecular recognition of the glutamate receptor

    M Kubo, E Shiomitsu, K Odai, T Sugimoto, H Suzuki, E Ito

    JOURNAL OF MOLECULAR STRUCTURE-THEOCHEM   634   145 - 157  2003.09

     View Summary

    To understand the mechanism of molecular recognition of glutamate receptors, we calculated the dipole moments, net charges, and electrostatic potentials of the agonists and antagonists of the glutamate receptors under aqueous conditions by the ab initio molecular orbital method at the HF/6-311++G(3df,2pd) level. All of the ligands had negative net charges at both termini and, consequently, formed negative electrostatic potentials at these termini. We further calculated the net charges and electrostatic potential of the S1S2 lobes of the glutamate receptor subunit GluR2 under aqueous conditions by the semempirical PM3 molecular orbital method, and found that the ligand-binding cleft of the S1S2 lobes formed a primarily positive electrostatic potential. A strongly positive electrostatic potential was formed particularly around Arg485 in the S1 lobe. A negative electrostatic potential was observed only in a small region around Glu657 in the S2 lobe in the ligand-binding cleft. When a ligand approaches the ligand-binding cleft, it may proceed to Arg485 in the S1 lobe, due to both repulsion by the negative electrostatic potential of Glu657 as well as the attraction of the strongly positive electrostatic potential of Arg485 itself. (C) 2003 Elsevier B.V. All rights reserved.

    DOI

  • Theoretical research on structures of gamma-aminobutyric acid and glutamic acid in aqueous conditions

    K Odai, T Sugimoto, M Kubo, E Ito

    JOURNAL OF BIOCHEMISTRY   133 ( 3 ) 335 - 342  2003.03

     View Summary

    Even though glutamic acid contains only one more carboxyl group than gamma-aminobutyric acid (GABA), these neurotransmitters are recognized by their own specific receptors. To understand the ligand-recognition mechanism of the receptors, we must determine the geometric and electronic structures of GABA and glutamic acid in aqueous conditions using the ab initio calculation. The results of the present study showed that the stable structure of GABA was the extended form, and it attracted both cations and anions. Glutamic acid only attracted cations and was stabilized in four forms in aqueous conditions: Type 1 (an extended form), Type 2 (a rounded form), and Types 3 and 4 (twisted forms of Type 1). The former two types had low energy and the energy barrier between them was estimated to be small. These results showed that most free glutamic acid is present as Type a, Type 2, and transient forms. The present results therefore suggest that the flexibility of the geometric structures of ligands should be taken into account when we attempt to elucidate the mechanism of recognition between ligands and receptors, in addition to the physicochemical characteristics of ligands and receptors.

    DOI CiNii

  • Ligand-receptor electrostatic interactions in molecular recognition of glutamate receptor.

    M Kubo, E Shiomitsu, K Odai, T Sugimoto, H Suzuki, E Ito

    BIOPHYSICAL JOURNAL   84 ( 2 ) 160A - 160A  2003.02

    Research paper, summary (international conference)  

  • PROJECTIONS OF THE OPTIC TECTUM IN RAINBOW TROUT ONCORHYNCHUS MYKISS(Physiology,Abstracts of papers presented at the 74^<th> Annual Meeting of the Zoological Society of Japan) :

    Kinoshita Masae, Yamamoto Naoyuki, Ito Hironobu, Urano Akihisa, Ito Etsuro

    Zoological science   20 ( 12 ) 1582 - 1582  2003

    CiNii

  • TRANSCRIPTION REPRESSOR CREB2 REGULATES LONG-TERM MEMORY IN LYMNAEA STAGNALIS(Physiology,Abstracts of papers presented at the 74^<th> Annual Meeting of the Zoological Society of Japan) :

    Wagatsuma Akiko, Sadamoto Hisayo, Kitahashi Takashi, Urano Akihisa, Ito Etsuro

    Zoological science   20 ( 12 ) 1580 - 1580  2003

    CiNii

  • ALTERATIONS IN TRANSCRIPTION AND TRANSLATION ACTIVITY OF C/EBP IN THE KEY NEURON DURING CONDITIONED TASTE AVERSION OF THE POND SNAIL(Physiology,Abstracts of papers presented at the 74^<th> Annual Meeting of the Zoological Society of Japan) :

    Hatakeyama Dai, Sadamoto Hisayo, Wagatsuma Akiko, Sugai Rio, Kitahashi Takashi, Sakakibara Manabu, Urano Akihisa, Ito Etsuro

    Zoological science   20 ( 12 ) 1587 - 1587  2003

    CiNii

  • EXPRESSION OF CREB1 ISOFORMS IN THE CNS OF THE POND SNAIL LYMNAEA STAGNALIS(Physiology,Abstracts of papers presented at the 74^<th> Annual Meeting of the Zoological Society of Japan) :

    Sadamoto Hisayo, Wagatsuma Akiko, Sugai Rio, Kitahashi Takashi, Ito Etsuro

    Zoological science   20 ( 12 ) 1587 - 1587  2003

    CiNii

  • Multiple-site optical recording for characterization of functional synaptic organization of the optic tectum of rainbow trout

    M Kinoshita, R Ueda, S Kojima, K Sato, M Watanabe, A Urano, E Ito

    EUROPEAN JOURNAL OF NEUROSCIENCE   16 ( 5 ) 868 - 876  2002.09

     View Summary

    To map the functional synaptic organization over a wide area in the optic tectum, we directly monitored two-dimensional propagation of postsynaptic depolarization evoked by firing of retinotectal afferents in optic tectum slices prepared from rainbow trout (Oncorhynchus mykiss), using a voltage-sensitive dye and a photodiode array system. The postsynaptic responses to afferent stimulation first propagated in the stratum opticum and stratum fibrosum et griseum superficiale in an anterograde fashion in the afferents and then expanded vertically into the deep layers. This vertical propagation appeared to occur along a bundle-like structure that corresponded well with a cluster of neurons whose somata are located in the stratum periventriculare. Pharmacological studies showed that these postsynaptic responses were mediated by ionotropic glutamate receptors. On the other hand, the optical signals appeared to consist of at least two components (a transient signal and a slow signal). The second transient signal summated with the first slow signal by paired stimulation, suggesting that the transient and slow signals originated from different cell types. Taken together, these results showed that the functional synaptic organization of the teleost optic tectum comprises of two depolarization-signal propagating paths along a horizontal layer structure and a vertical bundle-like structure and that these synaptic responses occur via glutamatergic transmission.

    DOI

  • Non-ocular dermal photoreception in the pond snail Lymnaea stagnalis

    K Chono, Y Fujito, E Ito

    BRAIN RESEARCH   951 ( 1 ) 107 - 112  2002.09

     View Summary

    Based on the results of previous behavioral experiments, researchers believe that sensitivity to light stimuli is not restricted to the eyes in the pond snail Lymnaea stagnalis. To determine the presence of a non-ocular dermal photoreception system and to examine the synaptic connections between this peripheral system and the central nervous system, we electrophysiologically examined the activities of the pedal nerves in L. stagnalis by light stimulation. The results demonstrated that light stimulation evokes non-ocular dermal photosensitive responses in the foot, that these responses exert inhibitory, afferent influences through the inferior pedal nerves to the pedal ganglia, and that these responses were independent of the ocular photoreception system in L. stagnalis. (C) 2002 Elsevier Science B.V. All rights reserved.

    DOI

  • Increased resistance to nitric oxide cytotoxicity associated with differentiation of neuroblastoma-glioma hybrid (NG108-15) cells

    K Kawahara, M Saitoh, T Nakajima, H Sato, M Tanaka, T Tojima, E Ito

    FREE RADICAL RESEARCH   36 ( 5 ) 545 - 554  2002.05

     View Summary

    Nitric oxide (NO), synthesized by the enzyme nitric oxide synthase (NOS), acts as an intercellular messenger associated with various physiological and pathological events. In this study, we investigated whether there exits a difference in the vulnerability to NO-induced cytotoxicity between undifferentiated and differentiated NG108-15 cells, and if so, the mechanisms responsible for the difference. Following a 7- to 8-day exposure to dibutyryl cAMP (dbcAMP), NG108-15 cells exhibited a neuron-like morphology associated with the expression of the neuronal protein, synaptophysin, and with increased NADPH-d activity. Neuron-like differentiated NG108-15 cells acquired resistance to exogenously applied NO. This increased resistance to NO toxicity in differentiated cells was almost completely cancelled out by inhibiting the activity of superoxide dismutase (SOD), but not by inhibiting the activity of NOS. The present study suggested that the activity of SOD increased in parallel with the activity of NOS associated with differentiation and was crucial for the acquired resistance to NO toxicity in differentiated cells.

    DOI

  • QUANTITATIVE ANALYSIS OF mRNA LEVEL FOR C/EBP IN THE SINGLE CELLS OF THE POND SNAIL(Physiology)(Proceedings of the Seventy-Third Annual Meeting of the Zoological Society of Japan) :

    Hatakeyama Dai, Sadamoto Hisayo, Kitahashi Takashi, Ando Hironori, Urano Akihisa, Ito Etsuro

    Zoological science   19 ( 12 ) 1471 - 1471  2002

    CiNii

  • Agonist-specific vibrational excitation of glutamate receptor by agonist binding

    M Kubo, E Shiomitsu, K Odai, T Sugimoto, H Suzuki, E Ito

    BIOPHYSICAL JOURNAL   82 ( 1 ) 620A - 620A  2002.01

    Research paper, summary (international conference)  

  • A thermodynamical study of the Schrödinger gear proposed in his clockwork hypothesis(jointly worked)

    Information   5   491 - 502  2002

  • Gap junctional channel inhibition alters actin organization and calcium propagation in rat cultured astrocytes

    Y Yamane, H Shiga, H Asou, E Ito

    NEUROSCIENCE   112 ( 3 ) 593 - 603  2002

     View Summary

    Astrocytes are connected by gap junctions, which provide intercellular pathways that allow a direct exchange of ions and small metabolites including second messengers and the propagation of electric currents. The roles of gap junctional communication on whole-cell morphology, cytoskeletal organization, and intercellular communication in astrocytes are not yet clear even in vitro, though there are many studies that have examined the active relation between gap junctions and actin filaments in astrocytes. Here we examined the effects of gap junction inhibitors, which do not interrupt the formation but rather the function of gap junctions, on whole-cell morphology, cytoskeletal organization. and intercellular communication in rat cultured astrocytes. Functional blockade of gap junctions during the formation of an astrocytic monolayer resulted in discordance of actin stress fibers between neighboring cells. even though whole-cell morphology of these cells did not change by such treatment. Mechanical stimulation-induced calcium wave propagation was significantly reduced in these actin-discordance cells even after thorough wash out. Differentiation of astrocytes in the presence of gap junction inhibitors was associated with morphological disarrangement among neighboring cells due to disordered alignment of actin stress fibers between cells.
    Our results indicate that gap junctional communication enables cell-to-cell coordination of actin stress fibers in astrocytes, thus enhancing intercellular communication through calcium spread. (C) 2002 IBRO. Published by Elsevier Science Ltd. All rights reserved.

    DOI

  • The nitric oxide/cyclic GMP pathway in the olfactory processing system of the terrestrial slug Limax marginatus

    S Fujie, H Aonuma, Ito, I, A Gelperin, E Ito

    ZOOLOGICAL SCIENCE   19 ( 1 ) 15 - 26  2002.01

     View Summary

    To examine the distribution of nitric oxide (NO)-generative cells and NO-responsive cells in the tentacles and procerebral lobes (olfactory processing center) of terrestrial slugs, we applied NADPH diaphorase (NADPH-d) histochemistry and NO-induced cyclic GMP (cGMP)-like immunohistochemistry. We found that NADPH-d reactive cells/fibers and cGMP-like immunoreactive cells/fibers were different, but they were localized adjacent to each other, in both the tentacles and the procerebral lobes. Then, we measured the concentration of NO that was generated around the procerebral lobes using an NO sensitive electrode, when the olfactory nerve was electrically stimulated as a replacement for an odorant stimulus. Stimulation of the olfactory nerve evoked an increase in NO concentration at nanomolar levels, suggesting that binding of nanomolar concentrations of NO to the prosthetic heme group activates soluble guanylyl cyclase. Taken together with previously reported physiological data, our results, therefore, showed that the NO/cGMP pathways are involved in slug olfactory processing.

    DOI PubMed CiNii

  • Optical detection of neuromodulatory effects of conditioned taste aversion in the pond snail Lymnaea stagnalis

    S Kojima, T Hosono, Y Fujito, E Ito

    JOURNAL OF NEUROBIOLOGY   49 ( 2 ) 118 - 128  2001.11

     View Summary

    Multiple site optical recording was used to analyze the neural activity changes caused by conditioned taste aversion (CTA) training in the pond snail Lymnaea stagnalis. In response to electrical stimulation of the median lip nerve, which transmits chemosensory signals of appetitive taste to the central nervous system, we optically detected large numbers of spikes in several parts of the buccal ganglion. The effects of CTA training on the spike responses were examined in two areas of the ganglion where the most active neural responses occurred. In one area (termed Area I) that included the N1 medial (NUM) cells, a class of central pattern generator interneurons involved in feeding behavior, the number of spikes in a period 1500-2000 ms after median lip nerve stimulation was significantly reduced in conditioned animals compared to control animals. In another area (termed Area II) positioned between buccal motoneurons, the B3 and B4CL (cluster) cells, the evoked spike responses were unaffected by CTA training. These results, taken together with our previous results indicating an enhancement of an inhibitory input to the NIM cells during CTA, suggest that an appetitive taste signal transmitted to the NIM cells through the median lip nerves is suppressed during CTA, resulting in a decrease of the feeding response. (C) 2001 John Wiley & Sons, Inc.

    DOI

  • チャコウラナメクジLimax marginatusの中枢および末梢神経系におけるNOS活性とNO誘導性cGMP含有細胞の分布

    藤江紗代子, 青沼仁志, 伊藤伊織, 伊藤悦朗

    日本神経科学大会プログラム・抄録集   24th   326  2001.09

    J-GLOBAL

  • チャコウラナメクジLimax marginatusの中枢および末梢神経系におけるNOS活性とNO誘導性cGMP含有細胞の分布

    藤江紗代子, 青沼仁志, 伊藤伊織, 伊藤悦朗

    神経化学   40 ( 2/3 ) 382  2001.09

    J-GLOBAL

  • Ca2+ signaling regulated by an ATP-dependent autocrine mechanism in astrocytes

    H Shiga, T Tojima, E Ito

    NEUROREPORT   12 ( 12 ) 2619 - 2622  2001.08

     View Summary

    Although the mechanisms of Ca2+, wave propagation in astrocytes induced,by mechanical stimulation have been well studied, it is still not known how the [Ca2+](i) increases in the stimulated cells. Here, we have analyzed the mechanisms of [Ca2+](i) increase in single, isolated astrocytes. Our results showed that there was an autocrine mechanism of Ca2+ regulation mediated by ATP in mechanically stimulated astrocytes. This autocrine mechanism induced the activation of phospholipase C via a G-protein, resulting in Ca2+ release from intracellular Ca2+ stores. A second pathway mediating a [Ca2+](i) increase was via a Ca2+ influx from the extracellular space, which, interestingly, suppressed an intracellular Ca2+ oscillation. These two different Ca2+ cascades are involved in signal transduction and may function separately during intercellular communication. NeuroReport 12:2619-2622 (C) 2001 Lippincott Williams & Wilkins.

  • A theoretical study of electronic and structural states of neurotransmitters: gamma-aminobutyric acid and glutamic acid

    K Odai, T Sugimoto, D Hatakeyama, M Kubo, E Ito

    JOURNAL OF BIOCHEMISTRY   129 ( 6 ) 909 - 915  2001.06

     View Summary

    As a first approach to understanding the mechanism for the recognition of a ligand by its receptor, we first calculated the electronic and structural states of ionized gamma -aminobutyric acid (GABA) and ionized glutamic acid using the ab initio method with the 6311++G (3df, 2pd) basis set. We paid special attention to the physicochemical characteristics of these molecules, such as the electric dipole moment, electrostatic potential, and electrostatic force, Even though GABA and glutamic acid are known to exert completely opposite influences in the mammalian brain by binding their specific receptors, the only difference in their chemical structures is that glutamic acid contains one more carboxyl group than GABA. As a result, we succeeded in showing that a difference of only one carboxyl group induces significant differences in the electronic and structural states between these molecules. These differences have a crucial influence on the electric dipole moments, the electrostatic potentials, and the electrostatic forces. The most remarkable finding of the present research is that the electrostatic potential formed by glutamic acid is composed of only negative parts, while that formed by GABA is separated into positive and negative parts. These results strongly suggest that GABA can approach either positively or negatively charged amino acids by adjusting its own orientation, while glutamic acid can approach only a positively charged binding site.

    DOI

  • Quantum chemical study of agonist-receptor vibrational interactions for activation of the glutamate receptor

    M Kubo, K Odai, T Sugimoto, E Ito

    JOURNAL OF BIOCHEMISTRY   129 ( 6 ) 869 - 874  2001.06

     View Summary

    To understand the mechanism of activation of a receptor by its agonist, the excitation and relaxation processes of the vibrational states of the receptor should be examined. As a first approach to this problem, we calculated the normal vibrational modes of agonists (glutamate and kainate) and an antagonist (6-cyano-7-nitroquinoxaline-2,3-dione: CNQX) of the glutamate receptor, and then investigated the vibrational interactions between kainate and the binding site of glutamate receptor subunit GluR2 by use of a semiempirical molecular orbital method (MOPAC2000-PM3). We found that two local vibrational modes of kainate, which were also observed in glutamate but not in CNQX, interacted through hydrogen bonds with the vibrational modes of GluR2: (i) the bending vibration of the amine group of kainate, interacting with the stretching vibration of the carboxyl group of Glu705 of GluR2, and (ii) the symmetric stretching vibration of the carboxyl group of kainate, interacting with the bending vibration of the guanidinium group of Arg485, We also found collective modes with low frequency at the binding site of GluR2 in the kainate-bound state. The vibrational energy supplied by an agonist may flow from the high-frequency local modes to the low-frequency collective modes in a receptor, resulting in receptor activation.

    DOI

  • Odor responses and spontaneous oscillatory activity in tentacular nerves of the terrestrial slug, Limax marginatus

    Ito, I, T Kimura, E Ito

    NEUROSCIENCE LETTERS   304 ( 3 ) 145 - 148  2001.05

     View Summary

    We studied the neural oscillatory activity in the peripheral olfactory system of the tentacles in the terrestrial slug, Limax marginatus, by extracellular recording, Recordings from the cut-ends of the inferior tentacular nerves connected to the inferior tentacular ganglia and sensory epithelia showed spontaneous oscillatory activity at frequencies of 0.1-30 Hz. This spontaneous activity was dominated by the 0.6-6 Hz band. Ethanol odor stimulation decreased the amplitude in the 0.6-6 Hz band and increased those in the 6-15 and 15-30 Hz bands. Antagonists of the gamma -aminobutyric acid (GABA) receptor, bicuculline and picrotoxin, resulted in suppression of spontaneous activity and modulated the odor response in the 0.6-6 Hz band. Our results indicate the involvement of GABA-mediated oscillatory activity in the tentacular nerves in the olfactory processing in molluscs. (C) 2001 Elsevier Science Ireland Ltd. All rights reserved.

    DOI

  • NO/cGMP pathway in the peripheral and central olfactory organs of the terrestrial slug Limax marginatus(Physiology)(Proceeding of the Seventy-Third Annual Meeting of the Zoological Society of Japan) :

    Fujie S, Aonuma H, Ito I, Ito E

    Zoological science   18 ( 0 ) 104 - 104  2001

    CiNii

  • A cyclic AMP-regulated negative feedforward system for neuritogenesis revealed in a neuroblastoma x glioma hybrid cell(jointly worked)

    Neuroscience   104   583 - 591  2001

    DOI

  • Complement receptor 3-like immunoreactivity in the superior and inferior tentacles of terrestrial slug, Limax marginatus

    D Hatakeyama, Ito, I, E Ito

    ZOOLOGICAL SCIENCE   18 ( 1 ) 5 - 10  2001.01

     View Summary

    Complement receptor 3 (CR3), one of cell adhesion molecules, plays a crucial role in secretion of mammalian neutrophils. To study whether CR3 is also involved in neurosecretion of gastropod molluscs, we examined the CR3-like immunoreactivity in the central nervous system (CNS) and the superior and inferior tentacles of the terrestrial slug, Limax marginatus. In the CNS of L. marginatus, we did not detect the specific immunoreactivity at all. In contrast, the CR3-like immunoreactivity was observed in the cell bodies and processes of collar cells of the superior and inferior tentacles. In particular, granules contained in the cell bodies of collar cells exhibited the CR3-like immunoreactivity. Retrograde labeling of horseradish peroxidase applied on the sensory epithelia (SE) of superior and inferior tentacles showed that the collar cells of these tentacles project their processes to the SE. in the previous study, homogenate of the superior tentacles injected into the body cavity of slugs stimulated spermatogenesis and simultaneously inhibited egg-laying behavior, suggesting that the tentacular hormone acts as gonadotropic hormone. Taken together, CR3 expressed in the collar cells is considered to be involved in the secretion of tentacular hormone in L. marginatus.

    DOI CiNii

  • A novel function of synapsin II in neurotransmitter release

    T Sugiyama, T Shinoe, Y Ito, H Misawa, T Tojima, E Ito, T Yoshioka

    MOLECULAR BRAIN RESEARCH   85 ( 1-2 ) 133 - 143  2000.12

     View Summary

    Although synapsin has been localized to presynaptic structures, its function remains poorly understood. In the present study, we investigated the presynaptic function of synapsin II using a synaptic vesicle recycling process using synapsin-II-overexpressing NG108-15 cells. Western blot analysis with antibodies for synaptic-vesicle-associated protein indicated that the number of synaptic vesicles was approximately doubled in synapsin II transfectants as reported previously. In differentiated synapsin-II-overexpressing and control cells, the application of high potassium induced strong intracellular calcium elevation along neurites and varicosities after differentiation and a weak calcium rise in the cell bodies. The uptake and release of the fluorescent dye FM1-43 revealed that synaptic vesicle recycling in synapsin-LI-transfected cells occurred with the same kinetics in the cell body and neuritic varicosities. Furthermore, the area labeled with FM1-43 fluorescence in the synapsin-II-transfected cells was approximately twice as much as in control cells after stimulation, and ATP released after synaptic vesicle fusion with the plasma membrane in synapsin-II-expressing cells was significantly elevated relative to controls. The number of synaptic vesicles paralleled the amount of transmitter released from the cells leading to the conclusion that the number of releasable synaptic vesicles were increased by synapsin II transfection into NG108-15 cells, suggesting that synapsin II may have a role in the regulation of synaptic vesicle number in presynapse-like structures in NG108-15 cells. (C) 2000 Elsevier Science BN. All rights reserved.

    DOI

  • Nitric oxide generation around buccal ganglia accompanying feeding behavior in the pond snail, Lymnaea stagnalis

    S Kobayashi, H Sadamoto, H Ogawa, Y Kitamura, K Oka, K Tanishita, E Ito

    NEUROSCIENCE RESEARCH   38 ( 1 ) 27 - 34  2000.09

     View Summary

    Although there are many lines of evidence for both the presence of nitric oxide synthase (NOS) in the central nervous system (CNS) and the effects of NO on activating and modulating the feeding circuit in Lymnaea stagnalis, there has been no direct evidence that NO generation in the CNS accompanies feeding behavior. In the present study, we used a NO specific electrode to measure the increase in NO concentration around the buccal ganglia when the lips of semi-intact preparations of L. stagnalis were stimulated by sucrose. The NO concentration of the buccal ganglia was significantly increased by an application of sucrose to the lips. A NO scavenger and a NOS inhibitor suppressed this increase in NO concentration. A pair of putative NO-generative neurons in the buccal ganglia, the B2 cells, are active during the inter-feeding phase, and the bursting of the B2 cell elicited by sucrose application starts simultaneously with the feeding response. The rhythmic pulses of NO generation corresponded well with the rhythmic bursting of the B2 cells, which itself corresponds to the 'fictive feeding response'. The present data provide the first direct evidence that NO is generated in the buccal ganglia of L, staganalis and is involved in a specific behavior such as Feeding. (C) 2000 Elsevier Science Ireland Ltd and the Japan Neuroscience Society. All rights reserved.

    DOI

  • Time-sharing contributions of A- and D-type K+ channels to the integration of high-frequency sequential excitatory post synaptic potentials at a model dendrite in rats

    Hiroshi Takagi, Ryo Sato, Masaya Mori, Tomoki Matsumoto, Minoru Saito, Etsuro Ito, Hideo Suzuki

    Neuroscience Letters   289 ( 3 ) 169 - 172  2000.08

     View Summary

    A- and D-type K+ channels (KA and KD channels) have unique physiological properties that play important roles in the integration of excitatory post synaptic potentials (EPSPs) in neuronal dendrites. These functions were analyzed using a computer program, NEURON, to simulate high- frequency sequential synaptic inputs, that can induce long-term potentiation (LTP). We paid close attention to the stability of the reduction of sequential EPSPs. When either KA or KD channels were included in models, the EPSP reduction ratios were less stable than containing both KA and KD channels. When both KA and KD channels were present in the model, the variance of EPSP reduction ratios was significantly smaller in comparison with that in the presence of either KA or KD channels alone. We thus concluded that the co-existence of KA and KD channels is necessary to produce stable EPSPs during the high-frequency synaptic stimulation necessary for induction of LTP. (C) 2000 Elsevier Science Ireland Ltd.

    DOI PubMed

  • A thermodynamical study of the clockwork hypothesis proposed by E. Schrodinger

    E Ito, E Shiomitsu, H Suzuki

    BIOPHYSICAL CHEMISTRY   86 ( 1 ) 85 - 93  2000.07

     View Summary

    In the present study, the 'clockwork' hypothesis proposed by Schrodinger was examined from the viewpoint of thermodynamics. Firstly, noticing a unidirectional transfer of entropy in a heat engine, the logic was briefly explained about a close relation between this entropy transfer and an irreversible cycle performed by a working body. Next, paying attention to two fundamental differences between a heat engine and a biological system, we considered an isolated system A(Sigma) consisting of three one-component systems (A(i), A, A(o)) and noted a case that the same molecules as the component ones flowed quasistatically into A(i) from the outside. Then, the unidirectional flows of the molecules, energy and entropy, which were induced by the above inflow in A(Sigma), were formulated on the basis of the equilibrium thermodynamics for an open system. Furthermore, it was clarified that the fundamental equation for these flows is the Schrodinger inequality and that the necessary-sufficient condition for this inequality is the existence of an irreversible cycle performed by A. Here A corresponds to a working body in a heat engine. It was, thus, concluded that the 'clockwork' hypothesis by Schrodinger is considered to be reasonable for a biological system composed of various irreversible subsystems. (C) 2000 Elsevier Science B.V. All rights reserved.

    DOI

  • Neuronal components of the superior and inferior tentacles in the terrestrial slug, Limax marginatus

    Ito, I, H Nakamura, T Kimura, H Suzuki, T Sekiguchi, K Kawabata, E Ito

    NEUROSCIENCE RESEARCH   37 ( 3 ) 191 - 200  2000.07

     View Summary

    To identify the types of neurons and to infer the patterns of connectivity in slug tentacles, we stained the neurons in the superior and inferior tentacles in the terrestrial slug, Limax marginatus, by backfilling of the tentacular nerves with Lucifer yellow. Four types of stained neurons, '(1) sensory neurons', '(2) gamma cells', '(3) ganglion cells', '(4) lateral cells', were identified both in the superior and inferior tentacles. Three subtypes of the sensory neurons, '(la) round sensory neurons', '(lb) spindle-shaped sensory neurons', and '(lc) small sensory neurons', were found in the digits. The gamma cells and the ganglion cells were interneurons. Three subtypes of gamma cells, '(2a) round monopolar gamma cells', '(2b) round bipolar gamma cells', and '(2c) large gamma cells', were present in the digits. The ganglion cells were composed of '(3a) monopolar ganglion cells','(3b) bipolar ganglion cells', and '(3c) elongated ganglion cells'. The monopolar and bipolar types were located both in the tentacular ganglia and digits, whereas the elongated type was present only in the tentacular ganglia. The lateral cells, whose function is unknown, were found in the dermo-muscular sheaths of the tentacles. Our study provides the first description of the neuronal map of inferior tentacles in gastropods. The results showed no differences in the morphological features of stained neurons between the superior and inferior tentacles in L. marginatus. (C) 2000 Elsevier Science Ireland Ltd and the Japan Neuroscience Society. All rights reserved.

    DOI

  • Acquisition of neuronal proteins during differentiation of NG108-15 cells

    T Tojima, Y Yamane, M Takahashi, E Ito

    NEUROSCIENCE RESEARCH   37 ( 2 ) 153 - 161  2000.06

     View Summary

    The differentiated type of neuroblastoma x glioma hybrid cell line, NG108-15, has widely been used in in vitro studies instead of primary-cultured neurons. Here we examined whether NG108-15 cells can be used as a model for studying the neuronal differentiation process. We compared the expression of neuronal proteins (neurofilament 200 (NF200), phosphorylated-NF200 (p-NF200), microtubule associated protein 2, synaptophysin, syntaxin 1, choline acetyltransferase, and acetylcholinesterase (AChE)) and a glial protein (vimentin) between undifferentiated and differentiated NG108-15 cells by immunocytochemistry and immunoblot analysis. The expression of all neuronal proteins, with the exception of NF200 and p-NF200, was positive in differentiated cells, but almost negative in undifferentiated cells. On the other hand, cytoskeletal intermediate filaments (NF200 and p-NF200) for neurons and that (vimentin) for glia were present in both undifferentiated and differentiated cells. Furthermore, a high expression of AChE mRNA was confirmed in differentiated cells by reverse transcription-PCR analysis. Our results showed that even though the expression of cytoskeletal filaments does not change during differentiation of NG108-15 cells, these cells during differentiation can serve as an appropriate tool for investigating and understanding the mechanisms involved in neuronal development and differentiation. (C) 2000 Elsevier Science Ireland Ltd and the Japanese Neuroscience Society. All rights reserved.

    DOI

  • Mechanical properties of membrane surface of cultured astrocyte revealed by atomic force microscopy

    H Shiga, Y Yamane, E Ito, K Abe, K Kawabata, H Haga

    JAPANESE JOURNAL OF APPLIED PHYSICS PART 1-REGULAR PAPERS SHORT NOTES & REVIEW PAPERS   39 ( 6B ) 3711 - 3716  2000.06

     View Summary

    In order to examine the mechanical properties of the membrane surface of astrocytes, we observed living astrocytes by atomic force microscopy (AFM) both in contact mode and force-mapping mode. Ridge-like structures reflecting actin filaments were observed in the topographic images in contact mode, but not in force-mapping mode, using a zero-loading force. When we measured the elasticity of astrocytes, we observed that the cell membrane above the nucleus was soft and the cell membrane above the cytosol was stiff. In particular, the parts reflecting actin filaments were very stiff. This effect of actin filaments on the elasticity of astrocytes was confirmed by the loss of actin filaments after application of actin-polymerization inhibitor.

    DOI CiNii

  • Nitric oxide suppresses fictive feeding response in Lymnaea stagnalis

    Suguru Kobayashi, Hiroto Ogawa, Yutaka Fujito, Etsuro Ito

    Neuroscience Letters   285 ( 3 ) 209 - 212  2000.05

     View Summary

    Fictive feeding activity was monitored in the buccal ganglia of semi-intact preparations of the pond snail, Lymnaea stagnalis, to examine the effects of nitric oxide (NO) released from motoneurons innervating the esophagus on the feeding response. The present results suggest that first
    even the low concentration of constitutive NO precisely regulates the feeding rhythm by suppressing high frequency feeding responses
    second, that the high concentration of NO released after activation of the feeding central pattern generator following appetitive stimulation of the lips suppresses the feeding rate, resulting in recurrent inhibition. This is the first direct evidence that NO can function to suppress rhythmic activity in the brain. Copyright (C) 2000 Elsevier Science Ireland Ltd.

    DOI PubMed

  • Complement receptor 3-like immunoreactivity in the light green cells and the canopy cells of the pond snail, Lymnaea stagnalis

    D Hatakeyama, Ito, I, S Kojima, Y Fujito, E Ito

    BRAIN RESEARCH   865 ( 1 ) 102 - 106  2000.05

     View Summary

    We observed CR3-like immunoreactivity in the central nervous system (CNS) and its surrounding peripheral nerves of the pond snail, Lymnaea stagnalis. Ln the CNS of L. stagnalis, the immunoreactivity presenting meshwork-like structure was detected in some neurosecretory cells, which an the light green cells (LGCs) and the canopy cells (CCs), both controlling the body growth. The immunoreactivity was also observed along the edges of median lip nerves. The immunoreactive regions in the median lip nerves appeared to form the axonal plates, from which the LGCs and the CCs release molluscan insulin-related peptides (MIPs) into the blood. By contrast, no immunoreactivity was detected in other neurosecretory cells or their release sites, fur example the caudodorsal cells and the cerebral commissure, which release ovulation hormones. The present findings, therefore, suggested that CR3 expresses only in the neurosecretory cells releasing MIPs in L. stagnalis. (C) 2000 Elsevier Science B.V. All rights reserved.

    DOI

  • Distribution and developmental changes in GABA-like immunoreactive neurons in the central nervous system of pond snail, Lymnaea stagnalis

    D Hatakeyama, E Ito

    JOURNAL OF COMPARATIVE NEUROLOGY   418 ( 3 ) 310 - 322  2000.03

     View Summary

    We examined three-dimensionally the arrangement of gamma-aminobutyric acid; (GABA)-like immunoreactive neurons in the central nervous system (CNS) of the pond snail, Lymnaea stagnalis, by a combination of immunohistochemistry and confocal laser scanning microscopy on whole-mount preparations. GABA-like immunoreactivity was detected in all ganglia of the adult CNS. The following distribution of immunoreactive cell bodies was noted in the adult snail. Buccal ganglia: one cell body and five pairs of cell bodies, cerebral ganglia: one pair of cell bodies, pedal ganglia: two single cell bodies, two pairs of cell bodies, and three pairs of cell clusters, and pleural ganglia: one pair of cell bodies. In the asymmetrical parietal ganglia, three cell bodies were located in the left parietal ganglion; three cell bodies and three cell clusters were located in the right parietal ganglion. In the single visceral ganglion, a few scattered individual cell bodies and a cell cluster were GABA-like immunoreactive. Our results showed that the occurrence of GABA is widely spread in the CNS of adult L. stagnalis. GABA-like immunoreactivity in the CNS was not detected in the embryo but; was observed after hatching, although the number of stained cells was less than in the adult, with the exception of those in the cerebral ganglia where their number decreased with maturation. Our results provide detailed maps of the central GABA-like immunoreactive neurons in juveniles, immatures, and adults oft. stagnalis. J. Comp. Neurol. 418:310-322, 2000. (C) 2000 Wiley-Liss, Inc.

    DOI

  • Developmental study of anatomical substrate for conditioned taste aversion in Lymnaea stagnalis

    H Sadamoto, M Yamanaka, D Hatakeyama, H Nakamura, S Kojima, M Yamashita, E Ito

    ZOOLOGICAL SCIENCE   17 ( 2 ) 141 - 148  2000.03

     View Summary

    The pond snail, Lymnaea stagnalis, is a useful preparation for analyzing the commonality between development and learning. To promote this analysis, the anatomical substrate should be provided upon which learning is superposed during development. Because we previously demonstrated that L. stagnalis change their ability of conditioned taste aversion (CTA) as a long-term memory from veliconcha embryos to immatures, we examined in the present study the numbers of cells and the volume of the buccal and cerebral ganglia in the snails at the critical developmental stages. The buccal and cerebral ganglia include the majority of neurons involved in the CTA. We found that the numbers of cells in these ganglia are almost saturated in the immatures, but the volumes of these ganglia still increase from the immatures to the adults. These results suggested that most of the cells indispensable to the CTA emerge at the immature stage, but that individual cells in the ganglia continue to enlarge even in adulthood. Furthermore, the key neuron for the CTA was found to mature at the immature stage. The present study provided the anatomical substrate upon the long-term CTA, by which snails can eat safe food in a wide territory.

    DOI CiNii

  • Elasticity mapping of living fibroblasts by AFM and immunofluorescence observation of the cytoskeleton

    H Haga, S Sasaki, K Kawabata, E Ito, T Ushiki, T Sambongi

    ULTRAMICROSCOPY   82 ( 1-4 ) 253 - 258  2000.02

     View Summary

    Using the force mapping mode of atomic force microscopy (AFM), we measured spatial distribution of elastic moduli of living mouse fibroblasts (NIH3T3) in a physiological condition. The nuclear portion of the cellular surface is about 10 times softer than the surroundings. Stiffer fibers are confirmed in the elastic images. In order to investigate origin of the softer nuclear portion and the stiffer fibers, we fixed the identical cells imaged by the AFM, and carried out immunofluorescence observation for three types of cytoskeletal filaments - actin filaments, microtubules, and intermediate filaments, using confocal laser scanning microscopy (CLSM). A comparison between the AFM and the CLSM images revealed that the elasticity of the cells was concerned not only with the distribution of actin network, but also with intermediate filaments, whereas microtubules had no large effect on the measured elasticity. (C) 2000 Elsevier Science B.V. All rights reserved.

    DOI

  • Relation between development of key neurons for learning and learning ability in the pond snail, Lymnaea stagnalis

    D Hatakeyama, H Sadamoto, E Ito

    EUROPEAN JOURNAL OF NEUROSCIENCE   12   94 - 94  2000

    Research paper, summary (international conference)  

  • The measurement of NO in the central circuitry for feeding in the pond snail, Lymnaea stagnalis

    H Sadamoto, S Kobayashi, E Ito

    EUROPEAN JOURNAL OF NEUROSCIENCE   12   91 - 91  2000

    Research paper, summary (international conference)  

  • Cellular mechanism of conditioned taste aversion in the pond snail, Lynmaea stagnalis, revealed by optical recording technique

    E Ito, S Kojima, T Hosono

    EUROPEAN JOURNAL OF NEUROSCIENCE   12   92 - 92  2000

    Research paper, summary (international conference)  

  • Normal mode analysis of ligands and receptor proteins using MOPAC2000

    Kubo, M, Ito, E

    Hokkaido University Computing Center News (in Japanese)   32   15 - 23  2000  [Invited]

  • Biophysical and biochemical aspects of nerve and glial cells as revealed by atomic force microscopy(jointly worked)

    Recent Res. Devel. Biophys. Chem.,   1   61 - 72  2000

  • Three-dimensional characterization of interior structures of exocytotic apertures of nerve cells using atomic force microscopy

    T Tojima, Y Yamane, H Takagi, T Takeshita, T Sugiyama, H Haga, K Kawabata, T Ushiki, K Abe, T Yoshioka, E Ito

    NEUROSCIENCE   101 ( 2 ) 471 - 481  2000

     View Summary

    We examined the interior structure of exocytotic apertures in synaptic vesicles of neuroblastoma x glioma hybrid cells using atomic force microscopy. The atomic force microscopy detected apertures of 50-100 nm in diameter at various depths within the varicosities of these cells. We were also able to image a regular radial pattern on the wall and lump-like structures at the bottom of these apertures. In contrast, scanning electron microscopy could only detect the apertures but not the fine details of their interior. The cells examined here exhibited the same electrophysiological properties and expression of synaptophysin and syntaxin 1 as presynaptic terminals, as studied by various electrophysiological and imaging techniques.
    Our results indicate that atomic force microscopy allows three-dimensional viewing of the fine structures located inside exocytotic apertures in nerve cells. (C) 2000 IBRO. Published by Elsevier Science Ltd. All rights reserved.

    DOI

  • Neuron-independent Ca2+ signaling in glial cells of snail's brain

    S Kojima, H Ogawa, T Kouuchi, T Nidaira, T Hosono, E Ito

    NEUROSCIENCE   100 ( 4 ) 893 - 900  2000

     View Summary

    To directly monitor the glial activity in the CNS of the pond snail, Lymnaea stagnalis, we optically measured the electrical responses in the cerebral ganglion and median lip nerve to electrical stimulation of the distal end of the median lip nerve. Using a voltage-sensitive dye, RH155, we detected a composite depolarizing response in the cerebral ganglion, which consisted of a fast transient depolarizing response corresponding to a compound action potential and a slow depolarizing response. The slow depolarizing response was observed more clearly in an isolated median lip nerve and also detected by extracellular recording. In the median lip nerve preparation, the slow depolarizing response was suppressed by an L-type Ca2+ channel blocker, nifedipine, and was resistant to tetrodotoxin and Na+-free conditions. Together with the fact that a delay from the compound action potential to the slow depolarizing response was not constant, these results suggested that the slow depolarizing response was not a postsynaptic response. Because the signals of the action potentials appeared on the saturated slow depolarizing responses during repetitive stimulation, the slow depolarizing response was suggested to originate from glial cells. The contribution of the L-type Ca2+ current to the slow depolarizing response was confirmed by optical recording in the presence of Ba2+ and also supported by intracellular Ca2+ measurement.
    Our results suggested that electrical stimulation directly triggers glial Ca2+ entry through L-type Ca2+ channels, providing evidence for the generation of glial depolarization independent of neuronal activity in invertebrates. (C) 2000 IBRO. Published by Elsevier Science Ltd. All rights reserved.

    DOI

  • Bimodal effects of acetylcholine on synchronized calcium oscillation in rat cultured cortical neurons(jointly worked)

    Neuroscience Letters   287   179 - 182  2000

    DOI

  • Big softer hole on living cells: Elasticity imaging with AFM

    K Kawabata, H Haga, T Nitta, Y Endo, M Nagayama, E Ito, T Sambongi

    SCANNING AND FORCE MICROSCOPIES FOR BIOMEDICAL APPLICATIONS II   3922   91 - 98  2000

     View Summary

    We have focused on effects of local mechanical properties of the cell on cell motion. By using atomic force microscopy, we measured spatial distribution of local elastic modulus on mouse fibroblasts (NIH3T3), which is living in a physiological condition. In order to examine validity of AFM elastic measurements, we measured local elastic modulus of gels as elastic reference materials. The results obtained with AFM were compared with values obtained by tensile creep method. It is veryfied that these values are proportional each other. The AFM experiments on living cells revealed that center area of cell surface is about 10 times softer than the surroundings and looks like a big softer hole in the elasticity image. We fixed the cell just after the AFM measurements and carried out immunofluorescence observation for cytoskeletal filaments of actin filaments, microtubules and intermediate filaments. A comparison between distribution of local elasticity and cytoskeletones indicates that harder area on the cell results mainly from concentration of actin filaments. However, We found that some areas like the big softer hole do not correspond to distribution of actin filaments.

  • Time-lapse viscoelastic imaging of living fibroblasts using force modulation mode in AFM

    H Haga, M Nagayama, K Kawabata, E Ito, T Ushiki, T Sambongi

    JOURNAL OF ELECTRON MICROSCOPY   49 ( 3 ) 473 - 481  2000

     View Summary

    Using the force modulation mode in atomic force microscopy, we have succeeded in capturing time-lapse viscoelastic images of living mouse fibroblasts (NIH3T3) for several hours in a physiological condition without damaging the fibroblasts. Elongation of the lamellipodia and swelling of blabs were observed in time-lapse topographic images, which were taken every 10 min. The corresponding viscoelastic responses at a frequency of 600 Hz were visualized as consecutive images. The stiffer part of the cell body was fairly stable and did not show morphological changes for over 1 h. This is probably due to excess condensation of the actin network, hardening the cell cortex, and lowering the cytoskeletal activity. The nuclear portion of the cell body seems to be slightly less viscous than the peripheral region.

  • Quantitative analyses of topography and elasticity of living and fixed astrocytes

    Y Yamane, H Shiga, H Haga, K Kawabata, K Abe, E Ito

    JOURNAL OF ELECTRON MICROSCOPY   49 ( 3 ) 463 - 471  2000

     View Summary

    The topography and elasticity of living and fixed astrocytes cultured from the rat cerebra were studied quantitatively by atomic force microscopy (AFM). Ridge-like structures reflecting F-actin beneath the cell membrane were prominent in the contact-mode images of living astrocytes. Many of these ridges became unclear after fixation (2%, glutaraldehyde). In addition, the ridge-like structures were invisible in the topography of living cells observed at zero-loading force in the force mapping mode, which is considered to show the real cell surface not pressed down by an AFM tip. The topography of fixed cells observed both in the contact mode and at zero-loading force in the force mapping mode was similar to that of living cells observed at zero-loading force in the force mapping mode, although some deformed areas were detected in the fixed cells. The elasticity map images of living astrocytes showed that the cell membrane above the nucleus was softer (2-3 kPa) than the surroundings, and that the cell membrane above F-actin was stiffer (10-20 kPa) than the surroundings. In the elasticity map images of fixed astrocytes, on the other hand, the elasticity of the cells was found to be relatively uniform (200-700 kPa) irrespective of the inner structures of cells. These results show that images observed by AFM should be carefully examined in consideration of the force introduced to specimens and the elasticity of specimens to find out the real surface topography.

  • Development of key neurons for learning stimulates learning ability in Lymnaea stagnalis

    M Yamanaka, D Hatakeyama, H Sadamoto, T Kimura, E Ito

    NEUROSCIENCE LETTERS   278 ( 1-2 ) 113 - 116  2000.01

     View Summary

    The pond snails, Lymnaea stagnalis, change their ability of conditioned taste aversion (CTA) during their development, for example, stage 29 embryos can acquire the CTA, whereas immature snails come to use a long-term memory to maintain the conditioned response. We thus examined the relationships between the learning ability and the development of key neurons (cerebral giant cells: CGCs) for this CTA. The immunoreactivity of serotonin, which is a main neurotransmitter employed in the feeding circuitry, was first observed in the CGCs at the stage 29. After hatching, the CGCs developed their neuropile faster than other cells in the buccal and cerebral ganglia, resulting in their early innervation at the immature stage. The present results, therefore, indicate that the development of key neurons for learning stimulates the developmental changes in learning ability. (C) 2000 Elsevier Science Ireland Ltd. All rights reserved.

    DOI PubMed CiNii

  • Associative learning in the pond snail, Lymnaea stagnalis

    E Ito, S Kobayashi, S Kojima, H Sadamoto, D Hatakeyama

    ZOOLOGICAL SCIENCE   16 ( 5 ) 711 - 723  1999.10

    Book review, literature introduction, etc.  

    DOI CiNii

  • Atomic force microscopic observation of three-dimensional morphological changes of neurons where stimulated by a neurotransmitter

    T Hosono, M Yamanaka, T Tojima, Y Yamane, H Sadamoto, D Hatakeyama, H Haga, K Kawabata, K Abe, E Ito

    JAPANESE JOURNAL OF APPLIED PHYSICS PART 1-REGULAR PAPERS SHORT NOTES & REVIEW PAPERS   38 ( 6B ) 3940 - 3945  1999.06

     View Summary

    As the first step in the study df morphological changes in neurons associated with their functional changes, we applied atomic force microscopy (AFM) for the observation of fine three-dimensional morphological changes in rat cerebellar granule cells stimulated by an agonist of glutamate receptors, N-methyl-D-aspartate (NMDA). The AFM revealed that NMDA changed the cross-sections of cell bodies from a trapezoid-like form to a triangle-like form within a minute. The fine hill-like structures on the top surfaces of the cell bodies became wider during the same period. These results were suggested to be induced by the depolymerization; of filamentous actin triggered by the entry of Ca2+ via cation channels complexed with the activated NMDA receptors.

    DOI CiNii

  • PKA-dependent regulation of synaptic enhancement between a buccal motor neuron and its regulatory interneuron in Lymnaea stagnalis

    H Nakamura, S Kobayashi, S Kojima, A Urano, E Ito

    ZOOLOGICAL SCIENCE   16 ( 3 ) 387 - 394  1999.06

     View Summary

    The cerebral giant cell (CGC) is known to play a crucial role in the regulation of feeding response in the pond snail, Lymnaea stagnalis. However, the mechanisms of signal transduction from the CGC to the following buccal motor neurons are not clear. In the present study, we examined whether cyclic AMP (cAMP)-dependent protein kinase (PKA) contributes to enhancement of a monosynaptic connection between the presynaptic CGC and the postsynaptic buccal motor neuron 1 (B1 cell). Injection of cAMP into the CGC or inhibition of phosphodiesterase by isobutylmethylxanthine in the CGC increased the amplitude of excitatory postsynaptic potential (EPSP) in the B1 cell, whereas no changes were detected in the electrical properties of the CGC. The synaptic enhancement in the B1 cell was completely blocked by inhibition of PKA in the CGC but did not require a de novo protein synthesis due to a PKA phosphorylation. The increase in the EPSP amplitude of B1 cell was associated with the increase in the amount of serotonin release from the CGC. These results hence provided the physiological evidence of the direct regulation of a synaptic enhancement by PKA in the CNS of L. stagnalis, indicating the completely different mechanism from that in the well-studied siphon- and gill-withdrawal reflex in Aplysia.

    DOI CiNii

  • Physiological characterization of lip and tentacle nerves in Lymnaea stagnalis

    H Nakamura, S Kojima, S Kobayashi, Ito, I, Y Fujito, H Suzuki, E Ito

    NEUROSCIENCE RESEARCH   33 ( 4 ) 291 - 298  1999.04

     View Summary

    The lip and tentacle nerves of the pond snail, Lymnaea stagnalis, were characterized using electrophysiological techniques. When the activity of those nerves was induced in lip-tentacle preparations, aversive taste signals were transmitted through all the lip and tentacle nerves, but appetitive signals could be recorded only through the superior lip nerve. In the CNS immersed in high Mg2+-high Ca2+ saline, electrical stimuli applied to any of the nerves failed to induce action potentials in one of the regulatory neurons (cerebral giant cell: CCC) involved in feeding responses, implying that the signals are polysynaptically transmitted to the CGC. Intracellular recordings revealed that the CGCs in semi-intact half-body preparations received both appetitive and aversive taste signals not only through the superior lip nerve but also through the median lip nerve. In addition, an osphradium was ruled out as a candidate for appetitive reception. The present results, together with our preceding data arrived at by the histochemical analyses, indicate that the appetitive taste transduction responsible for generating feeding responses is performed through the superior lip nerve with some contribution of the median lip nerve. The data showing that the CGC can receive various taste signals suggests that it may play a crucial role in feeding behavior as demonstrated in the study of conditioned taste-aversion. (C) 1999 Elsevier Science Ireland Ltd. All rights reserved.

    DOI PubMed CiNii

  • Optical detection of synaptically induced glutamate transport in hippocampal slices

    S Kojima, T Nakamura, T Nidaira, K Nakamura, N Ooashi, E Ito, K Watase, K Tanaka, K Wada, Y Kudo, H Miyakawa

    JOURNAL OF NEUROSCIENCE   19 ( 7 ) 2580 - 2588  1999.04

     View Summary

    Although it has long been believed that glial cells play a major role in transmitter uptake at synapses in the CNS, the relative contribution of glial and neuronal cells to reuptake of synaptically released glutamate has been unclear. Recent identification of the diverse glutamate transporter subtypes provides an opportunity to examine this issue. To monitor glutamate transporter activity, we optically detected synaptically induced changes of membrane potential from hippocampal CA1 field in slice preparations using a voltage-sensitive dye, RH155. In the presence of ionotropic glutamate-receptor blockers, synaptic inputs gave rise to a slow depolarizing response (SDR) in the dendritic field. The amplitude of SDR correlated well with presynaptic activities, suggesting that it was related to transmitter release. The SDR was found to be caused by the activities of glutamate transporters because it was not affected by blockers for GABA(A), nACh, 5-HT3, P-2x, or metabotropic glutamate receptors but was greatly reduced by dihydrokainate (DHK), a specific blocker for GLT-1 transporter, and by D,L-threo-beta-hydroxyaspartate (THA), a blocker for EAAC, GLAST, and GLT-1 transporters. When SDR was detected with RH482 dye, which stains both glial and neuronal cells, 1 mM DHK and 1 mM THA were equally effective in suppressing SDR. The SDR was very small in GLT-1 knockout mice but was maintained in gerbil hippocampi in which postsynaptic neurons were absent because of ischemia. Because GLT-1 transporters are exclusively expressed in astrocytes, our results provide direct evidence that astrocytes play the dominant role in sequestering synaptically released glutamate.

  • Histological characterization of lip and tentacle nerves in Lymnaea stagnalis

    H Nakamura, Ito, I, S Kojima, Y Fujito, H Suzuki, E Ito

    NEUROSCIENCE RESEARCH   33 ( 2 ) 127 - 136  1999.02

     View Summary

    The lip and tentacle nerves of the pond snail, Lymnaea stagnalis, were characterized using histological techniques. Anatomical drawings showed the detailed distributions of the superior lip, median lip, and tentacle nerves in the lip and tentacle; in particular it was found that the mouth is mainly innervated by the superior lip nerve. The tentacle nerve was clarified to form a zigzag structure along the extension direction in a shrinking tentacle. By backfilling of the superior lip nerve and/or the median lip nerve with fluorescent dyes, the neurons in the CNS made some clusters, whereas those stained from the tentacle nerve made other clusters. These stained neurons were not part of the central pattern generator or its regulatory neurons for feeding. The present results, therefore, suggest that the superior lip nerve may be employed as a principal factor in the chemosensory transduction from the mouth, and that no direct inputs occur through the lip and tentacle nerves to the central pattern generator or its regulatory neurons for feeding. (C) 1999 Elsevier Science Ireland Ltd. All rights reserved.

    DOI PubMed CiNii

  • Developmental changes in conditioned taste aversion in Lymnaea stagnalis

    M Yamanaka, H Sadamoto, D Hatakeyama, H Nakamura, S Kojima, T Kimura, M Yamashita, A Urano, E Ito

    ZOOLOGICAL SCIENCE   16 ( 1 ) 9 - 16  1999.02

     View Summary

    As the first step to study relationships between development and learning in the molluscan central nervous system,we examined developmental changes in acquisition and retention of a conditioned taste aversion (CTA) in the pond snail, Lymnaea stagnalis. We found that snails developed ability of a CTA as a long-term memory through three critical stages. Embryos in veliconcha started to respond to appetitive sucrose at the first critical stage. This response was in good agreement with morphological observations that embryos at this developmental stage seemed to be physically ready to eat. However, they could not associate this appetitive stimulus (conditioned stimulus: CS) with an aversive stimulus of KCI (unconditioned stimulus: UCS). At the second critical stage, embryos just before hatching acquired the CTA, but the conditioned response did not persist. Through this stage, they may acquire learning ability to safely seek out food in an external environment. At the third critical stage, immature snails with a 10 mm shell could use a long-term memory to maintain the conditioned response. This memory persisted for at least a month, showing that now they are able to maintain a long-term memory so that they can safely eat a variety of food when they cover wide territory to search for a mate. The present findings indicate that the development of learning ability in snails, which secures acquisition of better survival ability, is coincident with the major changes in their life cycle.

    DOI CiNii

  • Surface structures of cultured type 2 astrocytes revealed by atomic force microscopy

    Y Yamane, D Hatakeyama, H Haga, K Abe, E Ito

    ZOOLOGICAL SCIENCE   16 ( 1 ) 1 - 7  1999.02

     View Summary

    The incomplete morphological characterization of type 2 astrocytes is in pari responsible for the slow progress of studies on these cells. To examine and characterize type 2 astrocytes morphologically, three-dimensional fine structures of the surfaces of type 2 astrocytes cultured from rat cerebella were studied by a combination of atomic force microscopic and immunocytochemical techniques. Atomic force microscopy (AFM) revealed irregular ridge-like structures that form a meshwork distributed throughout the cell body surfaces and the thick processes. These ridges were found to be of two heights (31 nm and 82 nm). This finding indicates two possible configurations responsible for shaping the meshwork: (1) two structures of different thickness are beneath the cell membrane; and (2) two structures are located at two different depths from the cell membrane. On the other hand, immunocytochemical studies for tubulin and glial fibrillary acidic protein (GFAP) revealed that these cytoskeletal filaments are similarly distributed within the resolution power of a light microscope. However, no detectable structures were obtained by actin staining. The immunocytochemical findings suggest that the AFM-revealed ridges forming the irregular meshwork on the cell surfaces may reflect very fine bundles of tubulin and/or GFAP. Therefore, AFM study, with the help of immunocytochemical study, is a powerful tool for characterizing cell morphology. The results of the present study reveal the first morphological characterization of type 2 astrocytes.

    DOI CiNii

  • Direct measurment of nitric oxide (NO) in central nervous system of Lymnaea stagnalis.

    Kobayashi S, Sadamoto H, Ogawa H, Ito E

    Seibutsu Butsuri   39 ( 0 ) S64  1999

    DOI CiNii

  • Reexamination of fine surface topography of nerve cells revealed by atomic force microscopy(jointly worked)

    Bioimages   7   89 - 94  1999

  • Dynamics of astrocyte adhesion as analyzed by a combination of atomic force microscopy and immunocytochemistry: The involvement of actin filaments and connexin 43 in the early stage of adhesion

    Yukako Yamane, Hatsuki Shiga, Hiroaki Asou, Hisashi Haga, Kazushige Kawabata, Kazuhiro Abe, Etsuro Ito

    Archives of Histology and Cytology   62 ( 4 ) 355 - 361  1999

     View Summary

    We observed the time-dependent morphological alteration of astrocytes during their adhesion by atomic force microscopy (AFM) and investigated the relationships between this morphological alteration and the localization of actin filaments and connexin 43 by immunocytochemistry. The fine processes observed as fine ridge-like structures by AFM were closely concerned with actin filaments by immunocytochemistry. During the adhesion of astrocytes, actin filaments appeared to be aligned regularly beyond the borders among different cells. Detectable connexin immunoreactivity was changed in the following regions: 1) the tips of fine cell processes and the cell margin when astrocytes started to adhere
    2) the border of cells when astrocytes tightly adhered
    and 3) non-specific sites when astrocytes became a cluster. In the former two cases, the immunopositive spots for connexin were observed to colocalize with the tips of cell processes with actin filaments. These results strongly suggest that connexin associated with actin filaments at the tip of cell processes plays an important role in the early stage of the adhesion of astrocytes. These observations afford valuable clues for understanding the glial communication.

    DOI PubMed CiNii

  • Three-dimensional reconstruction and mapping of serotonin-like immunoreactive neurons in the central nervous system of the pond snail, Lymnaea stagnails, with the confocal laser scanning microscope(jointly worked)

    Bioimages   7   1 - 12  1999

  • Effects of electrical stimulation of the tentacular digits of a slug upon the frequency of electrical oscillations in the procerebral lobe

    Ito, I, T Kimura, H Suzuki, T Sekiguchi, E Ito

    BRAIN RESEARCH   815 ( 1 ) 121 - 125  1999.01

     View Summary

    To find the primary mechanism for the frequency changes of electrical oscillations in the procerebral (PC) lobe of a slug, we electrically stimulated the tip, middle and basal regions of the digits of the superior and inferior tentacles and recorded the local field potentials from the PC lobe. Stimuli to the middle and basal regions of the digits of the inferior tentacle significantly decreased the frequency of electrical oscillations in the PC lobe, whereas those to the tip region of the digits of the inferior tentacle and all regions of the digits of the superior tentacle increased it. These findings suggest that the change in the frequency of electrical oscillations in the PC lobe depends on the excited region in the digits, providing the first presentation of the physiological difference in the olfactory function between the superior and inferior tentacles. (C) 1999 Elsevier Science B.V. All rights reserved.

    DOI PubMed CiNii

  • A theoretical approach to the functional changes in membrane proteins by phosphorylation(jointly worked)

    Journal of Biochemistrey, Molecular Biology and Biophysics   2   215 - 224  1999

  • Roles of A- and D-type K channels in EPSP integration at a model dendrite

    H Takagi, R Sato, M Mori, E Ito, H Suzuki

    NEUROSCIENCE LETTERS   254 ( 3 ) 165 - 168  1998.10

     View Summary

    We examined the roles of A- and D-type K channels in the integration of EPSPs, particularly EPSP reduction, in a model dendrite using a computer simulation program (NEURON), instead of conventional electrophysiological methods which present technical difficulties. We obtained two important results: (1) KD channels play a crucial role in every synaptic input event, and (2) KA channels affect reduction of the second EPSP only when the second synaptic input is applied with a short interval (less than or equal to 100 ms). These results suggest that KD channels, which have not yet been analyzed experimentally, play a major role in synaptic integration in dendrites by altering their cable properties. (C) 1998 Elsevier Science Ireland Ltd. All rights reserved.

    DOI PubMed CiNii

  • Sensory preconditioning for feeding response in the pond snail, Lymnaea stagnalis

    S Kojima, S Kobayashi, M Yamanaka, H Sadamoto, H Nakamura, Y Fujito, R Kawai, M Sakakibara, E Ito

    BRAIN RESEARCH   808 ( 1 ) 113 - 115  1998.10

     View Summary

    We demonstrated a sensory preconditioning in the pond snail, Lymnaea stagnalis. An appetitive sucrose solution (a conditioned stimulus: CS1) and weak vibration (another conditioned stimulus: CS2) were first associated, and then the CS2 and an aversive KCl solution (an unconditioned stimulus: UCS) were done. To build the conditioning, two different training procedures, spaced and massed, were examined. After the both training, the sensory preconditioning was built: significantly fewer feeding response to the CS1 became elicited; slower latency to the first bite to the CS1 was induced. No significant differences on the memory retention between these training procedures were found in the sensory preconditioning. (C) 1998 Elsevier Science B.V. All rights reserved.

    DOI PubMed CiNii

  • Operant conditioning of escape behavior in the pond snail, Lymnaea stagnalis

    S Kobayashi, S Kojima, M Yamanaka, H Sadamoto, H Nakamura, Y Fujito, R Kawai, M Sakakibara, E Ito

    ZOOLOGICAL SCIENCE   15 ( 5 ) 683 - 690  1998.10

     View Summary

    Operant conditioning that the pond snail, Lymnaea stagnalis, suppressed its naturally occurring behavior of escape from a water tank was examined by using a negative reinforcement (i.e. an aversive stimulus) prepared outside the tank. During the training period, the number of escapes from a tank was strongly suppressed. One of behavioral factors for this suppression was confirmed as the elongation of latency to the first escape after training. The effects on the memory retention were examined in the massed and spaced training procedures. The latter procedure interposes a rest interval between three sets of 20-min training sessions, whereas the former has the same number of training sessions with no rest interval within 60 min. The memory retention by the massed training was observed within 20 min after training. By the spaced training, the learning acquisition was found to be stronger, which was observed as the slower latency to the first escape, than by the massed training, but the longer-lasting memory retention, which had been expected first, was not formed. These results suggest that once Lymnaea recognize the external environment is safe after training, they may extinguish their memory of the past situation quickly, resulting in no or very little difference in the memory retention by two different training procedures in this operant conditioning. Together with the facts that classical conditioning and its neuronal mechanisms in Lymnaea were previously clarified, the present findings may help to address not only the neuronal basis of operant conditioning but also the relation between classical and operant conditioning.

    DOI CiNii

  • Analysis of sensory-input pathways in the CNS of pond snail Lymnaea stagnalis by using an optical recording technique.

    Kojima S., Nidaira T., Kouuchi T., Ito E.

    Biophysics   38 ( 2 ) S82  1998.09

    CiNii

  • The neural pathways of withdrawal response in Limnasa stagnalis.

    Kobayashi S., Ito I., Nakamura H., Ito E.

    Biophysics   38 ( 2 ) S78  1998.09

    CiNii

  • AFM analysis of morphological changes in cerebellar granule cells induced by agonists for receptors.

    Hosono T., Yamanaka M., Tojima T., Sadamoto H., Kawabata K., Abe K., Ito E.

    Biophysics   38 ( 2 ) S201  1998.09

    CiNii

  • Expression of neuronal and glial proteins in the differentiated and non-differentiated neuroblastomaX glioma hybrid cell line

    Tojima T., Ito E.

    Biophysics   38 ( 2 ) S199  1998.09

    CiNii

  • Imaging the Viscoelasticity of Living Cell with AFM(IV)

    Kawabata K., Ishizuka H., Morimoto M., Haga H., Ito E., Abe K., Sambongi T.

    Biophysics   38 ( 2 ) S144  1998.09

    CiNii

  • Synaptic enhancement induced by cAMP between a cerebral interneuron and a buccal motoneuron involved in the feeding behavior of Lymnaea stagnalis

    Nakamura H., Ito E.

    Biophysics   38 ( 2 ) S138  1998.09

    CiNii

  • Imaging the Viscoelasticity of Living Cell with AFM(III)

    Haga H., Sasaki S., Nitta T., Kawabata K., Ito E., Abe K., Sambongi T.

    Biophysics   38 ( 2 ) S144  1998.09

    CiNii

  • Atomic Force Microscopic Observation of Fine Surface Structures Which Reflect Cytoskeletons in Glial Cells

    YAMANE Y., HATAKEYAMA D., HAGA H., KAWABATA K., ABE K., ITO E.

    Meeting abstracts of the Physical Society of Japan   53 ( 2 ) 857 - 857  1998.09

    CiNii

  • Observation of the localization of neurotransmitters in Lymnaea central nervous system with the confocal scanning laser microscope

    HATAKEYAMA Dai, ITO Etsuro

    Meeting abstracts of the Physical Society of Japan   53 ( 2 ) 858 - 858  1998.09

    CiNii

  • The relation between the feeding circuitry and the distribution of neurons including NO synthase in the central nervous system of the gastropod molluse

    SADAMOTO Hisayo, HATAKEYAMA Dai, KOJIMA Satoshi, ITO Etsuro

    Meeting abstracts of the Physical Society of Japan   53 ( 2 ) 858 - 858  1998.09

    CiNii

  • Histochemical study on the relation between NO-generative neurons and central circuitry for feeding in the pond snail, Lymnaea stagnalis

    H Sadamoto, D Hatakeyama, S Kojima, Y Fujito, E Ito

    NEUROSCIENCE RESEARCH   32 ( 1 ) 57 - 63  1998.09

     View Summary

    To examine whether nitric oxide (NO)-generative neurons are included in the central circuitry for generation of feeding pattern in the pond snail, Lymnaea stagnalis, two staining techniques for NADPH diaphorase and serotonin (5-HT) were applied for its central nervous system (CNS). The former technique is known to show localization of NO synthase; the latter is well employed as a marker for the feeding circuitry because 5-HT is a main transmitter in it. In the buccal ganglion, B2 motoneuron was found to be a putative NO-generative neuron. This motoneuron is not involved directly in the coordination of feeding pattern but is activated simultaneously with the feeding to control the oesophageal and gut tissues for the digestion. Taking account of the diffusion effects of NO, the NO released from B2 motoneuron, when the feeding is started, is thought to sufficiently modulate the feeding circuitry. In the cerebral ganglion, the superior lip nerve, the median lip nerve and the tentacle nerve included both putative NO-generative fibers and serotonergic fibers. These fibers are not identical, but the NO released in the nerves may activate the serotonergic fibers, resulting in the influence upon the initiation of the feeding. Therefore, our present findings clearly showed that NO is not involved in transmission within the central circuitry for the feeding, but suggested that NO can crucially affect the feeding behavior, such as initiation and modulation of the feeding pattern. (C) 1998 Elsevier Science Ireland Ltd. All rights reserved.

    DOI PubMed CiNii

  • The entropy generation in visual-pigment system by the absorption of light

    E Ito, T Komatsu, H Suzuki

    BIOPHYSICAL CHEMISTRY   74 ( 1 ) 59 - 70  1998.08

     View Summary

    We first showed a general theory that reception of information from the outside in a receptor system is accompanied both by an inflow of entropy and by a generation of entropy depending on the reliability of the actual reception mechanism. Then, considering a case for the absorption of light by the visual-pigment system of visual cell, we calculated the time(t)-dependent change in the number N-2(t) of excited visual-pigments to obtain the entropy increase. We thus arrived at the following four conclusions: (1) One or two photons can be detected with a reliability of at least 54%; (2) In compensation for this detection, entropy &gt; 1.12 x log2 is generated; (3) An incident photon of frequency nu from a light source of temperature T-s yields an entropy of h nu/T-s; and (4) Depending on the characteristics of the visual-pigment system, another entropy being different from (2) is generated in proportion to N-2(t). (C) 1998 Elsevier Science B.V. All rights reserved.

    DOI PubMed

  • Imaging elastic properties of soft materials immersed in water using force modulation mode in atomic force microscopy

    H Haga, S Sasaki, M Morimoto, K Kawabata, E Ito, K Abe, T Sambongi

    JAPANESE JOURNAL OF APPLIED PHYSICS PART 1-REGULAR PAPERS SHORT NOTES & REVIEW PAPERS   37 ( 6B ) 3860 - 3863  1998.06

     View Summary

    Using the force modulation mode in atomic force microscopy (AFM), we have succeeded in imaging elastic properties of agar gels immersed in water. The elastic images of ap ar have been captured simultaneously with the topographic images. Stiffer grains of agar whose size is about 200 nm can be clearly seen in the elastic image of 3.0% agar, while they are not so visible in the case of 1.5% agar. These grains probably correspond to aggregation of agar which cannot be observed in the topographic images. We also measured force-versus-distance curves using AFM to confirm that the absolute values of elastic modulus (Young's modulus) of agar coincide with the bulk values measured using the conventional stress-strain method. The estimated values of the elastic moduli with the AFM were 40 and 90 kPa for 1.5% and 3.0% agar gels, respectively. These are in good agreement with the respective bulk values of 30 and 80 kPa obtained using the conventional method.

    DOI CiNii

  • Comparative atomic force and scanning electron microscopy for fine structural images of nerve cells

    T Tojima, D Hatakeyama, Y Yamane, K Kawabata, T Ushiki, S Ogura, K Abe, E Ito

    JAPANESE JOURNAL OF APPLIED PHYSICS PART 1-REGULAR PAPERS SHORT NOTES & REVIEW PAPERS   37 ( 6B ) 3855 - 3859  1998.06

     View Summary

    Although we can routinely obtain fine structural images of cells by atomic force microscopy (AFM), the adequacy and reliability of morphological information acquired from these AFM images remain to be examined. In this report, we compared images of the line structures of nerve cells as observed by both AFM and scanning electron microscopy (SEM). Although AFM revealed the structure of the top views of cells in greater detail than SEM, their side structures were better observed by SEM. The linear structures in the neural processes detected only by AFM were confirmed, by immunofluorescence staining, to be reflections of the cytoskeletal structures located beneath the cell membrane. These differences between the AFM and the SEM images reflected the characteristics of the detection systems and methods used for sample preparation. Therefore, these results revealed that more detailed information on cell morphology can be obtained by using both AFM and SEM to advantage.

    DOI CiNii

  • Fine surface images that reflect cytoskeletal structures in cultured glial cells by atomic force microscopy

    Y Yamane, D Hatakeyama, T Tojima, K Kawabata, T Ushiki, S Ogura, K Abe, E Ito

    JAPANESE JOURNAL OF APPLIED PHYSICS PART 1-REGULAR PAPERS SHORT NOTES & REVIEW PAPERS   37 ( 6B ) 3849 - 3854  1998.06

     View Summary

    The morphology of cultured glial cells was examined using a combination of atomic force microscopy (AFM) and immunofluorescence staining for cytoskeletons. The meshwork of type-1 astrocytes consisted of thick longitudinal and thin lateral lines on the cell surfaces observed by AFM, the former lines were confirmed to be reflections of actin filaments. The astrocytic processes of type-2 astrocytes were observed to be rugged on AFM. These structures were mainly affected by microtubules. Immunofluorescence imaging of microglia revealed that actin filaments and microtubules were arranged radially and wavily along the cell edge, respectively. AFM could detect these radial and wavy structures clearly. These results show that AFM can provide information on the cytoskeletons of glial cells, indicating that AFM is a useful tool for the morphological characterization of cells.

    DOI CiNii

  • Imaging Viscoelasticity of Living Nerve Cell with AFM(III)~Fine Globular Morphology in the Peripheral Region~

    HAGA H., MORIMOTO M., SASAKI S., KAWABATA K., ITO E., ABE K., SAMBONGI T.

    Meeting abstracts of the Physical Society of Japan   53 ( 1 ) 738 - 738  1998.03

    CiNii

  • Elastic properties of living fibroblasts as imaged using force modulation mode in atomic force microscopy

    S Sasaki, M Morimoto, H Haga, K Kawabata, E Ito, T Ushiki, K Abe, T Sambongi

    ARCHIVES OF HISTOLOGY AND CYTOLOGY   61 ( 1 ) 57 - 63  1998.03

     View Summary

    Using the force modulation mode in atomic force microscopy, we measured elastic properties of living mouse fibroblasts (NIH3T3) in a culture medium, The topographic images of the cellular surface and the corresponding elastic images of the cellular surface were able to be captured simultaneously with high spatial resolution, The consecutive images were useful for examining time-dependent changes in the cellular surface, We observed that some cells continued to shrink and change their softness for 2 hours, Then the force modulation mode in atomic force microscopy shows potential use in analyzing time-dependent regional elastic properties of living cells with high spatial resolution.

    DOI PubMed CiNii

  • Histological analysis of nervous system involved in chemoreception in Lymnaea stagnalis

    NAKAMURA H., ITO I., ITO E., FUJITO Y., SUZUKI H.

    Biophysics   37   S113  1997.10

    CiNii

  • Effects of expression of synapsin II and chorine acetyltransferase cDNA on the morphology of nerve cells

    YAMANE Y., TOJIMA T., ITO E., YOSHIDA A., MISAWA H., SUGIYAMA T., YOSHIOKA T.

    Biophysics   37   S116  1997.10

    CiNii

  • Fine structure of exocytotic aperture in nerve cells revealed by AFM

    TOJIMA T., YAMANE Y., KAWABATA K., ITO E., TAKAGI H., TAKESHITA T., YOSHIOKA T., USHIKI T., ABE K.

    Biophysics   37   S116  1997.10

    CiNii

  • 8a-P-4 Imaging the Viscoelasticity of Living Cell with AFM

    Haga H., Morimoro M., Sasaki S., Kawabata K., Ito E., Abe K., Sambongi T.

    Meeting abstracts of the Physical Society of Japan   52 ( 2 ) 853 - 853  1997.09

    CiNii

  • Enhancement of an inhibitory input to the feeding central pattern generator in Lymnaea stagnalis during conditioned taste-aversion learning

    S Kojima, H Nanakamura, S Nagayama, Y Fujito, E Ito

    NEUROSCIENCE LETTERS   230 ( 3 ) 179 - 182  1997.07

     View Summary

    To study the neuronal mechanism of a conditioned taste-aversion (CTA) learning in the pond snail Lymnaea stagnalis, we examined the synaptic connection between the neuron 1 medial (N1M) cell and the cerebral giant cell (CGC), the former is an interneuron in central pattern generator for the feeding response and the latter is a regulatory neuron to the central pattern generator. Inhibitory postsynaptic potential (IPSP) which was evoked in the N1M cell by activation of the CGC was larger and lasted longer in the conditioned animal than that in the control animal. The electrical properties of the cell body of CGC and the responses of the CGC to the chemosensory inputs were not changed during the CTA learning. These results, together with the previous report indicating the existence of excitatory projection from the N1M cell to the feeding motoneuron, suggest that enhanced IPSP in the N1M cell may underlie the suppression of feeding responses in the Lymnaea CTA learning. (C) 1997 Elsevier Science Ireland Ltd.

    DOI PubMed CiNii

  • Practical scan speed in atomic force microscopy for live neurons in a physiological solution

    S Nagayama, T Tojima, M Morimoto, S Sasaki, K Kawabata, T Ushiki, K Abe, E Ito

    JAPANESE JOURNAL OF APPLIED PHYSICS PART 1-REGULAR PAPERS SHORT NOTES & REVIEW PAPERS   36 ( 6B ) 3877 - 3880  1997.06

     View Summary

    We examined the practical scan speed for the observation of live neurons in a physiological solution using atomic force microscopy (AFM) with a desired vertical resolution of the order of 10(-8) mi which was reasonable when taking into account that a flicker of extracellular protein and saccharide on the neurons in the solution occurred during an observation period of a couple of minutes. The practical scan speed was found to be under 40 mu m/s, therefore, if we applied AFM using 100 lines and 100 pixels per line to an observation area of 20 mu m x 20 mu m, the minimum period for acquiring one image was estimated to be about 2 min. This procedure gave us good images that represented the slow three-dimensional dynamics in live neurons, such as the retrograde movement of surface protuberances, but suggested that another approach was required to detect fast structural changes induced by stimulation.

    DOI CiNii

  • 29a-WE-4 Histological analysis of sensory- and inter-neurons involved in conditioned taste-aversion learning in Lymnaea stagnalis

    Nakamura H, Kojima S, Ito E, Fujito Y, Suzuki H

    Meeting abstracts of the Physical Society of Japan   52 ( 1 ) 766 - 766  1997.03

    CiNii

  • Differential neuroethological effects of aversive and appetitive reinforcing stimuli on associative learning in Lymnaea stagnalis

    S Kojima, M Yamanaka, Y Fujito, E Ito

    ZOOLOGICAL SCIENCE   13 ( 6 ) 803 - 812  1996.12

     View Summary

    It is necessary to determine whether, in the same species and for the same behavior, aversive and appetitive conditioning yield different strengths and periods of either acquisition or retention. To this end, we first examined the effects of various chemo-sensory and physical stimuli on feeding and avoidance behavioral responses in the pond snail, Lymnaea stagnalis. Then, using these findings, we constructed classical-conditioning paradigms with aversive and appetitive stimuli. In the aversive conditioning paradigm, an appetitive stimulus (sucrose), which increased the feeding response, was paired with an aversive stimulus (KCI, quinidine sulfate or electric shock), which inhibited the feeding behavior. Upon presentation of KCI, the first type of aversive conditioning, which is generally called ''taste-aversion learning with cessation of feeding response'', was acquired quickly and persisted for up to a month. When using a noxious stimulus (quinidine sulfate or electric shock) inducing pain we additionally found the second type of aversive conditioning, in which the previously appetitive stimulus (sucrose) not only failed to increase the feeding response, but came to elicit an avoidance response. This second type conditioning took longer to acquire and persisted for a shorter period of time than the first type. On the other hand, the appetitive conditioning paradigm paired a neutral stimulus (vibratory) with an appetitive stimulus (sucrose). The strength and period for acquisition and retention of this appetitive leamed response were very similar to those of the second type aversive conditioning but not to the first one. On the basis of these behavioral analyses, the neuronal mechanisms of the two types of aversive and appetitive conditioning were discussed.

    DOI CiNii

  • Developmental analysis of taste-aversion learning in the pond snail, Lymnaea stagnalis.

    S Kojima, M Yamanaka, S Nagayama, H Sadamoto, H Nakamura, Y Fujito, M Yamashita, E Ito

    PROGRESS IN BIOPHYSICS & MOLECULAR BIOLOGY   65   PG314 - PG314  1996

    Research paper, summary (international conference)  

  • Molecular orbital study on changes in electronic state and molecular structure of membrane protein by phosphorylation

    T Sugimoto, E Ito

    PROGRESS IN BIOPHYSICS & MOLECULAR BIOLOGY   65   PA337 - PA337  1996

    Research paper, summary (international conference)  

  • 3D-structural observation of synaptic formation with AFM

    S Nagayama, M Morimoto, T Tojima, K Kawabata, Y Fujito, S Ogura, K Abe, T Ushiki, E Ito

    PROGRESS IN BIOPHYSICS & MOLECULAR BIOLOGY   65   PG313 - PG313  1996

    Research paper, summary (international conference)  

  • AFM Observation of Three-Dimensional Five Structural Changes in Living Neurons(jointly worked)

    Bioimages   4   111  1996

  • Imaging Nerve-Terminal Structure by Atomic Force Microscopy(jointly worked)

    Acta Histochemica et Cytochemica   29   553  1996

  • β-アミロイド蛋白質によって誘導されるアルツハイマー型のカリウムチャネル異常(共著)

    実験医学   13   71 - 73  1995

  • Scanning Probe Microscopy(jointly worked)

    The Cell   27   534  1995

  • The Law of Entropy for Biological Systems Biewed as a Biological Clodk(jointly worked)

      8   112  1995

  • Role of GABA, Ca2+and phosphorylation of GTP-Binding Protein in Associative Learning of the Marine Snail. Hermissenda crassicornis(jointly worked)

    Proceedings of the 10th Symposium on Biological and Physiological Engineering   10   225  1995

  • Alzheimer's phenotype potassium channel dysfunction in human skin fibroblasts induced by β-amyloid protein

    Experimental Medicine   13   71  1995

  • INTRACELLULAR CA2+ CONCENTRATION CHANGE OF T24 CELL UNDER IRRADIATION IN THE PRESENCE OF TIO2 ULTRAFINE PARTICLES

    H SAKAI, E ITO, RX CAI, T YOSHIOKA, Y KUBOTA, K HASHIMOTO, A FUJISHIMA

    BIOCHIMICA ET BIOPHYSICA ACTA-GENERAL SUBJECTS   1201 ( 2 ) 259 - 265  1994.11

     View Summary

    We reported that malignant cells are inactivated by photo-excited TiO2 particles (Cai, R.-X., et al. (1992) Cancer Res. 52, 2346-2348). In the present study, the process of cell death of a human bladder cell line T24 with TiO2 irradiated TiO2 was investigated by monitoring the time course change in intracellular calcium concentration ([Ca2+](i)) under UV irradiation using calcium fluorescence indicator, fura-2. In the presence of photo-excited TiO2 particles (100 mu g/ml), [Ca2+](i) showed a sapid two-step increase; while in the absence of TiO2, it exhibited only a slight and monotonous increase or maintained a constant level. The rapid elevation of [Ca2+](i) in the presence of photo-excited TiO2 particles was caused by the influx of extracellular Ca2+ through the plasma membrane and cell death occurred only after the second rapid elevation of [Ca2+](i). These results suggested that the cell membrane permeability to Ca2+ was promoted prior to cell death.

  • AGONIST-INDUCED RISE IN INTRACELLULAR CALCIUM OF LENS EPITHELIAL-CELLS - EFFECTS ON THE ACTIN CYTOSKELETON

    NS RAFFERTY, KA RAFFERTY, E ITO

    EXPERIMENTAL EYE RESEARCH   59 ( 2 ) 191 - 201  1994.08

     View Summary

    Primary cultures of rabbit and skate lens epithelia were used to investigate the effect of calcium release from intracellular stores upon the actin cytoskeleton. Primary cultures were loaded with fura-2 AM and intracellular calcium, i.e. (Ca2+)i, quantitated using a Hamamatsu Photonics digital imaging system. Agonists used were bombesin, inositol-1,4,5-trisphosphate (IP3), thapsigargin (Tg), neuropeptide Y (NPY) and calcium chloride. Recordings were typically made on seven cells in each case. We found that IP3 caused a 6-8-fold immediate release of (Ca2+)i in rabbit cells, but skate cells showed no response unless permeabilized with saponin, whereupon an increase of about 50% occurred. Tg induced release from internal stores in rabbit cells, but had no effect on skate cells. Bombesin caused a large increase in (Ca2+)i release in both, while NPY had no effect in either. Skate cells incubated in calcium-free EGTA-Ringer&apos;s solution responded rapidly to addition of 5 mM CaCl2, whereas only three of 35 rabbit cells responded, and in gradual fashion. After calcium imaging, the cells were fixed and stained with rhodamine phalloidin or with an antibody against IP3 receptor (IP3R) conjugated to FITC. Fluorescence microscopy revealed that the actin cytoskeleton had reorganized from the normal stress fiber pattern into polygonal networks. Tg caused the same structures to form in rabbit cells, but bombesin had no effect. IP3 receptor was located intracellularly, presumably on endoplasmic reticulum, and was not associated with plasma membranes. The rapid response of rabbit cells may have been caused by the DMSO in which fura-2 was dissolved.
    We have found an interesting difference in agonist-induced calcium release between rabbit and skate cells. The latter may utilize either a Ca-Na exchanger or capacitative calcium entry, which could reflect a difference in lens accommodative mechanisms. This seems relevant in view of the fact that the rabbit lens accommodates through change in shape, whereas the skate lens does so through translation of position.

  • SOLUBLE BETA-AMYLOID INDUCTION OF ALZHEIMERS PHENOTYPE FOR HUMAN FIBROBLAST K+ CHANNELS

    R ETCHEBERRIGARAY, E ITO, CS KIM, DL ALKON

    SCIENCE   264 ( 5156 ) 276 - 279  1994.04

     View Summary

    Although beta-amyloid is the main constituent of neurite plaques and may play a role in the pathophysiology of Alzheimer's disease, mechanisms by which soluble beta-amyloid might produce early symptoms such as memory loss before diffuse plaque deposition have not been implicated. Treatment of fibroblasts with beta-amyloid (10 nM) induced the same potassium channel dysfunction previously shown to occur specifically in fibroblasts from patients with Alzheimer's disease-namely, the absence of a 113-picosiemen potassium channel. A tetraethylammonium-induced increase of intracellular concentrations of calcium, [Ca2+]i, a response that depends on functional 113-picosiemen potassium channels. was also eliminated or markedly reduced by 10 nM beta-amyloid. Increased [Ca2+]i induced by high concentrations of extracellular potassium and 166-picosiemen potassium channels were unaffected by 10 nM beta-amyloid. In Alzheimer's disease, then, beta-amyloid might alter potassium channels and thus impair neuronal function to produce symptoms such as memory loss by a means other than plaque formation.

    DOI PubMed CiNii

  • INTRACELLULAR CALCIUM SIGNALS ARE ENHANCED FOR DAYS AFTER PAVLOVIAN CONDITIONING

    E ITO, K OKA, C COLLIN, BG SCHREURS, M SAKAKIBARA, DL ALKON

    JOURNAL OF NEUROCHEMISTRY   62 ( 4 ) 1337 - 1344  1994.04

     View Summary

    Previous observations have implicated GABA as a neurotransmitter released by the vestibular sensory neurons (''hair cells'') of the snail Hermissenda onto visual sensory neurons, the type B cells, whose cell bodies are the sites of biophysical and biochemical changes during and following Pavlovian conditioning. Still other observations demonstrated that light-GABA pairings that simulate stimuli presented during Pavlovian conditioning cause prolonged elevation of intracellular Ca2+ and transformation of GABA-induced synaptic inhibition into excitation. Intracellular Ca2+ signals in response to GABA perfused onto the postsynaptic type B terminal branches are shown here to be prolonged on days after conditioning, but not after control paradigms. These and past results demonstrate two separate sites, i.e., the cell body and the terminal branches, for learning-induced changes after Pavlovian conditioning.

    DOI

  • 軟体動物の古典的条件づけを通して見た学習・記憶の分子機構

    蛋白質核酸酵素   39   2310  1994

  • EFFECT OF SEROTONIN AND TRICYCLIC ANTIDEPRESSANTS ON INTRACELLULAR CALCIUM CONCENTRATIONS IN SPISULA OOCYTES

    R JUNEJA, E ITO, SS KOIDE

    CELL CALCIUM   15 ( 1 ) 1 - 6  1994.01

     View Summary

    Microspectrofluorometry and video imaging techniques were used to study and to compare the changes in intracellular calcium concentrations ([Ca2+](i)) of individual Fura-2 loaded Spisula oocytes treated with serotonin (5-hydroxytryptamine, 5-HT) or tricyclic antidepressants. In the present study, we showed that 5-HT increased [Ca2+](i) in freshly isolated Spisula oocytes suspended in artificial sea water. In the absence of extracellular Ca2+, 5-HT did not influence [Ca2+](i). Stimulation of [Ca2+](i) by 5-HT was blocked by calcium channel blocker, e.g. verapamil, and by tricyclic antidepressants. These observations combined with our previous results on the effects of 5-HT, tricyclic antidepressants and verapamil on calcium uptake suggest that the increase in [Ca2+](i) induced by 5-HT results from an influx of extracellular calcium through calcium channels, which can be blocked by tricyclic antidepressants.
    The use of the Fura-P imaging technique allowed single-cell measurements and defined changes induced by 5-HT In [Ca2+](i) which is the net result of calcium uptake and release of intracellular calcium from storage sites in individual Spisula oocytes.

    DOI PubMed CiNii

  • INTERNAL CA2+ MOBILIZATION IS ALTERED IN FIBROBLASTS FROM PATIENTS WITH ALZHEIMER-DISEASE

    E ITO, K OKA, R ETCHEBERRIGARAY, TJ NELSON, DL MCPHIE, B TOFELGREHL, GE GIBSON, DL ALKON

    PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA   91 ( 2 ) 534 - 538  1994.01

     View Summary

    The recent demonstration of Kf channel dysfunction in fibroblasts from Alzheimer disease (AD) patients and past observations of Ca2+-mediated K+ channel modulation during memory storage suggested that AD, which is characterized by memory loss and other cognitive deficits, might also involve dysfunction of intracellular Ca2+ mobilization. Bombesin-induced Ca2+ release, which is inositol trisphosphate-mediated, is shown here to be greatly enhanced in AD fibroblasts compared with fibroblasts from control groups. Bradykinin, another activator of phospholipase C, elicits similar enhancement of Ca2+ signaling in AD fibroblasts. By contrast, thapsigargin, an agent that releases Ca2+ by direct action on the endoplasmic reticulum, produced no differences in Ca2+ increase between AD and control fibroblasts. Depolarization-induced Ca2+ influx data previously demonstrated the absence of between-group differences of Ca2+ pumping and/or buffering. There was no correlation between the number of passages in tissue culture and the observed Ca2+ responses. Furthermore, cells of all groups were seeded and analyzed at the same densities. Radioligand binding experiments indicated that the number and affinity of bombesin receptors cannot explain the observed differences. These and previous observations suggest that the differences in bombesin and bradykinin responses in fibroblasts and perhaps other cell types are likely to be due to alteration of inositol trisphosphate-mediated release of intracellular Ca2+.

    DOI PubMed CiNii

  • Neuronal development and apoptosis(jointly worked)

    Human Cell   7   13  1994

  • Molecular mechanisms of learning and memory in classically conditioned molluscs(jointly worked)

    Protein, Nucleic Acids and Enzyme   39   2310  1994

  • USE OF CULTURED FIBROBLASTS IN ELUCIDATING THE PATHOPHYSIOLOGY AND DIAGNOSIS OF ALZHEIMERS-DISEASE

    HM HUANG, R MARTINS, S GANDY, R ETCHEBERRIGARAY, E ITO, DL ALKON, J BLASS, G GIBSON

    CALCIUM HYPOTHESIS OF AGING AND DEMENTIA   747   225 - 244  1994

    DOI

  • POTASSIUM CHANNEL DYSFUNCTION IN FIBROBLASTS IDENTIFIES PATIENTS WITH ALZHEIMER-DISEASE

    R ETCHEBERRIGARAY, E ITO, K OKA, B TOFELGREHL, GE GIBSON, DL ALKON

    PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA   90 ( 17 ) 8209 - 8213  1993.09

     View Summary

    Since memory loss is characteristic of Alzheimer disease (AD), and since K+ channels change during acquisition of memory in both molluscs and mammals, we investigated K+ channel function as a possible site of AD pathology and, therefore, as a possible diagnostk index as well. A 113-pS tetraethylammonium (TEA)-sensftive K+ channel was consistendy absent from AD ribroblasts, while it was often present in young and aged control fibroblasts. A second (166-pS) K+ channel was present in all three groups. Elevated external potassium raised intracellular Ca2+ in all cases. TEA depolarized and caused intracellular Ca2+ elevation in young and aged control fibroblasts but not AD fibroblasts. The invariable absence of a 113-pS TEA-sensitive K+ channel and TEA-induced Ca2+ signal indicate K+ channel dysfunction in AD fibroblasts. These results suggest the possibility of a laboratory method that would diagnostically distinguish AD patients, with or without a family history of AD, from normal age-matched controls and also from patients with non-AD neurological and psychiatric disorders.

    DOI PubMed CiNii

  • NEW IMPLICATIONS OF MEMORY MECHANISMS FOR ALZHEIMERS-DISEASE

    R ETCHEBERRIGARAY, E ITO, K OKA, B TOFELGREHL, GE GIBSON, DL ALKON

    NEUROSCIENCE RESEARCH COMMUNICATIONS   13   S7 - S10  1993.06

     View Summary

    Previous studies of molluscan and mammalian neural networks have implicated potassium channels, calcium-dependent kinases and a small G-protein (Cp20) in associative memory storage. Since Alzheimer's disease is characterized by memory deficits and possible changes in PKC activation, we studied potassium channel function in AD. Patch-clamp experiments revealed the absence of a 113 pS TEA-sensitive K+ channel in fibroblasts from Alzheimer's but not control patients. These results suggest a role for potassium channel dysfunction in Alzheimer's disease.

  • MOLECULAR AND BIOPHYSICAL STEPS IN THE STORAGE OF ASSOCIATIVE MEMORY

    DL ALKON, C COLLIN, E ITO, CJ LEE, TJ NELSON, K OKA, M SAKAKIBARA, BG SCHREURS, T YOSHIOKA

    MOLECULAR BASIS OF ION CHANNELS AND RECEPTORS INVOLVED IN NERVE EXCITATION, SYNAPTIC TRANSMISSION AND MUSCLE CONTRACTION   707   500 - 504  1993

    DOI PubMed CiNii

  • LONG-TERM TRANSFORMATION OF AN INHIBITORY INTO AN EXCITATORY GABAERGIC SYNAPTIC RESPONSE

    DL ALKON, JV SANCHEZANDRES, E ITO, K OKA, T YOSHIOKA, C COLLIN

    PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA   89 ( 24 ) 11862 - 11866  1992.12

     View Summary

    For a constant membrane potential, a predominantly inhibitory GABAergic synaptic response is shown to undergo long-term transformation into an excitatory response after pairing of exogenous gamma-aminobutyric acid (GABA) with postsynaptic depolarization or pairing of pre- and postsynaptic stimulation. Current- and voltage-clamp experiments suggest that this synaptic transformation is due to a shift from a net increase of conductance to a net decrease of conductance in response to GABA. GABA-induced elevation of intracellular calcium is prolonged after the same stimulus pairing and may, therefore, contribute to this synaptic transformation via Ca2+-activated phosphorylation pathways. This synaptic transformation, which does not follow unpaired stimulus presentations, occurs in a neuronal compartment spatially separated from the soma, which also changes during stimulus pairing.

    DOI

  • DELAYED APPEARANCE OF G-PROTEIN COUPLED SIGNAL TRANSDUCTION SYSTEM IN DEVELOPING CEREBELLAR PURKINJE-CELL DENDRITES

    H TAKAGI, H TAKIMIZU, T YOSHIOKA, N SUZUKI, E ITO, Y KUDO

    NEUROSCIENCE RESEARCH   15 ( 3 ) 206 - 212  1992.11

     View Summary

    To investigate the relation between the function of Ca2+-activated K+ channels and phosphoinositide turnover, we have examined the physiological and pharmacological characteristics of ionotropic and metabotropic quisqualate (QA) receptors in rat cerebellar Purkinje cells during development using the slice-patch method combined with Ca2+ imaging. The typical response to QA obtained from a rat on postnatal day (PND) 21 consisted of three components: (1) a fast inactivating inward current, (2) a slow inward current, and (3) a slow outward current. The slow inward current was abolished in Ca2+-free medium. while the fast inactivating inward current and the slow outward current remained unaffected. The slow outward current which appeared to be activated via a metabotropic receptor was not observed in the Purkinje cell of PND 7 rat, in which dendrites were poorly developed but its amplitude increased linearly with PND. QA caused significant increases in [Ca2+]i in the fully developed dendritic region of the Purkinje cells even in Ca2+-free medium, suggesting a dendritic localization of the metabotropic receptors.

    DOI

  • EFFECT OF EXTRACELLULAR PHOSPHATIDYLINOSITOL ON C-MYC GENE-EXPRESSED HUMAN RENAL-CANCER CELL-LINE

    S NOGUCHI, Y KUBOTA, T SHUIN, E ITO, H INOUE, T YOSHIOKA

    BIOCHEMICAL AND BIOPHYSICAL RESEARCH COMMUNICATIONS   182 ( 2 ) 644 - 650  1992.01

    DOI

  • THE ROLE OF CALCIUM IN PROLONGED MODIFICATION OF A GABAERGIC SYNAPSE

    C COLLIN, E ITO, K OKA, T YOSHIOKA, JV SANCHEZANDRES, LD MATZEL, DL ALKON

    JOURNAL OF PHYSIOLOGY-PARIS   86 ( 1-3 ) 139 - 145  1992

     View Summary

    Caudal hair cell impulses cause postsynaptic inhibition of ipsilateral type B photoreceptors in the snail Hermissenda. This inhibition is shown to be GABAergic according to a number of criteria. HPLC, mass spectrophotometric, and immunocytochemical techniques demonstrated the presence of GABA in the hair cells and their axons. GABA agonists and antagonists mimic and block the synaptic effect in a manner consistent with endogenous GABAergic transmission. Other properties, including I-V relations, conductance changes and reversal potentials, are comparable for exogenous GABA responses and endogenous effects of the hair cell impulses. This inhibitory synapse has been found to undergo a long-lasting transformation into an excitatory synapse if GABA release is paired with post-synaptic depolarization. GABA, via GABA(A) and GABA(B) receptors in the B cell, causes the opening of calcium sensitive chloride and potassium channels that leads to the post-synaptic hyperpolarization. GABA also induces a long-lasting intracellular calcium elevation at the terminal branches of the B cell that greatly outlasts the voltage responses. Synaptic transformation induced by pairings is caused by a decrease in both GABA induced chloride and potassium conductances in the post-synaptic B cell, as well as a significant prolongation of the intracellular calcium accumulation in the B cell's terminal axonal branches.

  • A MACRO IMAGE-ANALYSIS OF FURA-2 FLUORESCENCE TO VISUALIZE THE DISTRIBUTION OF FUNCTIONAL GLUTAMATE RECEPTOR SUBTYPES IN HIPPOCAMPAL SLICES

    Y KUDO, T NAKAMURA, E ITO

    NEUROSCIENCE RESEARCH   12 ( 3 ) 412 - 420  1991.11

     View Summary

    The distribution of functional glutamate receptor subtypes was visualized as regional changes in intracellular Ca2+ concentration induced by administration of a specific agonist for each subtype. An image of the fura-2 fluorescence from a whole hippocampal slice was directly excited at 340 or 380 nm through an optical fibre and observed via a low-magnification objective lens (X 4). A heterogeneous distribution of N-methyl-D-aspartate (NMDA) and non-NMDA subtypes was demonstrated by the ratio of fluorescence intensities before and after administration of each agonist. This 'macro' image analysis can reveal distributions of multiple functional receptors in a living brain slice.

    DOI

  • DEVELOPMENTAL ASSEMBLY OF CALCIUM-MOBILIZING SYSTEMS FOR EXCITATORY AMINO-ACIDS IN RAT CEREBELLUM

    E ITO, A MIYAZAWA, H TAKAGI, T YOSHIOKA, T HORIKOSHI, K YANAGISAWA, T NAKAMURA, Y KUDO, M UMEDA, K INOUE, K MIKOSHIBA

    NEUROSCIENCE RESEARCH   11 ( 3 ) 179 - 188  1991.08

     View Summary

    The postnatal development of calcium-mobilizing systems was studied by both microfluorometric imaging analysis of Ca2+ on living rat cerebellar slices and immunohistochemical labeling of phosphatidylinositol 4,5-bisphosphate (PIP2) and inositol 1,4,5-trisphosphate binding protein (IP3BP) in fixed rat cerebellum. Stimulation with quisqualate (QA) or N-methyl-D-aspartate (NMDA) enhanced the Ca2+ level only diffusely on postnatal day (PND) 3, but more discretely on PNDs 7 and 15. On PND 21, QA-induced responses were localized in the molecular layer especially, but not in the granular layer. By contrast, NMDA mobilized Ca2+ prominently in the granular layer, but only weakly in the molecular layer. Localized expression of PIP2 in the molecular layer paralleled QA-induced Ca2+ mobilization, but IP3BP was expressed more diffusely. The present study offers the first direct evidence that PIP2, but not IP3BP, is essential for QA-induced Ca2+ mobilization in the cerebellar cortex.

    DOI

  • AN APPROACH TO IMAGING OF LIVING CELL-SURFACE TOPOGRAPHY BY SCANNING TUNNELING MICROSCOPY

    E ITO, T TAKAHASHI, K HAMA, T YOSHIOKA, W MIZUTANI, H SHIMIZU, M ONO

    BIOCHEMICAL AND BIOPHYSICAL RESEARCH COMMUNICATIONS   177 ( 2 ) 636 - 643  1991.06

    DOI

  • DEVELOPMENT OF CALCIUM SIGNALING SYSTEMS IN POSTNATAL RAT PURKINJE-CELL

    E ITO, T YOSHIOKA

    BIOMEDICAL RESEARCH-TOKYO   12 ( S2 ) 119 - 121  1991

     View Summary

    In order to examine whether a transient appearance of glutamate receptor in developing rat Purkinje cell in coupled to PI turnover, we have studied Ca2+ mobilization induced by quisqualate or NMDA using fura-2 analyzing system in combination with immunohistochemical staining analysis with anti-PIP2 antibody and/or anti-IP3 binding protein antibody.

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Industrial Property Rights

  • Cell Test for Alzheimer's Disease(共著)(U. S. Patent, Serial No. 08/056,456)

    Patent

     View Summary

    *

Awards

  • Society Award

    2017   The Zoological Society of Japan  

    Winner: ITO Etsuro

  • (社)日本動物学会Zoological Science Award

    2004  

  • Zoological Science Award

    2004  

  • (社)日本動物学会奨励賞

    1999  

  • Young Scientist Award, The Zoological Sciety of Japan

    1999  

Research Projects

  • タンパク質の超高感度測定法の開発

    共同研究

  • ミツバチ「8の字ダンス」に対する分子生物学・神経生理学的解析

    その他の研究制度

  • 軟体動物を用いた学習・記憶の分子機構の研究

    その他の研究制度

  • Molecular Mechanism of Learning and Memory in Hobneybee

    The Other Research Programs

  • Molecular Mechanism of Learning and Memory in Molluscs

    The Other Research Programs

Specific Research

  • 新型コロナ感染症・インフルエンザ等の感染症同時測定法の開発

    2021  

     View Summary

    新型コロナウイルスのスパイクタンパク質に対する超高感度抗原検査法を開発し,10-18 moles/assayまでが検出可能であることがわかった.一方、ヌクレオカプシドタンパク質については,10-17 moles/assayの検出限界を得た.生きているウイルスについては,他機関で紫外線照射によって不活化したものを譲渡いただき,104 RNA copies/assayまで検出可能であることが分かった.インフルエンザウイルスA型ならびにB型についても,他機関から入手して実験を進めている.これらはバイオセーフティレベル2であるので,早稲田大学への申請後に使用が可能となっている.A型の方がB型よりも感度良く計測が出来ている.

  • 学習による行動変化におけるインスリンの作用機序の解明

    2020   戸谷勇輝

     View Summary

    ヨーロッパモノアラガイLymnaea stgnalisは、ショ糖溶液とKCl溶液の連続投与により味覚嫌悪学習を習得する。この味覚嫌悪学習が長期記憶として保持されるためには脳内のインスリンの働きが重要であることが示唆されていた。今年度は、次の研究成果を得た。(1)実験者の技術の有無に寄らずに一定の学習成績を出すために、コンピュータ制御による完全自動化の学習装置を作製した。(2)学習後の軽い絶食によって、味覚嫌悪学習の記憶が呼びされることを見出した。さらには、その際に脳内のインスリン発現量が増加していることも明らかとなった。すなわち脳内インスリンが、味覚嫌悪学習の記憶呼び出しに重要であった。

  • 尿水アディポネクチン濃度測定による新規CKD分類指標の提案

    2019  

     View Summary

    糖尿病などによる慢性腎臓病(CKD)の重症度は、現在は尿中アルブミン量と糸球体濾過量の両者で分類される。しかしながら、この指標では医師の診断結果との乖離が指摘されている。我々は、これまでに血中や尿中に含まれる極微量のタンパク質を超高感度で定量する方法を開発してきた。そして本研究では「アディポネクチン」に着目した。アディポネクチンは糖尿病になると血中で減少すると報告されている。しかし我々の実験結果では、糖尿病患者における血中アディポネクチンは実際にはそれほど大きな減少は認められず、一方で、尿中アディポネクチン濃度は、糖尿病によるCKDの重症度に比例して増加することが明らかとなった。

  • 獲得形質遺伝の可能性探索

    2018  

     View Summary

    親の獲得形質は子に遺伝するのか?この問題をモノアラガイのオランダとカナダの系統ならびにそれらのF1を用い、2つの学習を施して研究した。また、セロトニンとドーパミンの脳内濃度を測定した。味覚嫌悪学習ではオランダが他よりも優秀で、脳内セロトニン量も有意な差があった。呼吸オペラント学習ではカナダが他よりも優秀で、かつドーパミン濃度も有意に異なっていた。一方で、成績が良いまたは悪い系統内での子孫について、味覚嫌悪学習での鍵刺激となるショ糖への応答性を調べたところ、どちらの子孫でも有意な差はなかった。すなわち、優秀な系統とそうでない系統は存在するものの、その機構解明は今後の課題となった。

  • 脳内インスリンは薬か?毒か?

    2017  

     View Summary

    淡水産巻貝であるモノアラガイは、味覚嫌悪学習が習得でき、それが長期記憶として保持される。この機構にはインスリンとセロトニンの両方の反応過程が関わっていることが、我々の先行研究から示唆されてきた。そこで本研究では両者の関係を調べたところ、(1)弱い飢餓時には味覚嫌悪学習の成績が良く、かつ脳内のセロトニンレベルは低くなっていること、(2)強い飢餓時には味覚嫌悪学習は成立せず、かつ脳内のセロトニンレベルが高くなっていること、(3)強い飢餓時の動物の脳内にインスリンを注入すると、セロトニンレベルが下がり、そして味覚嫌悪学習が改善されることが分かった。

  • 非増幅・迅速・簡便核酸測定法の開発

    2017   山角薪之介, 長 寛貴

     View Summary

    我々は超高感度なタンパク測定ELISA法を開発した実績があり、今回は、さらにこの測定系を拡張するために、今までにない核酸検出に取り組んだ。それは「核酸の増幅を必要としない」超高感度核酸測定の実現である。本研究では、結核菌群に特異的に存在するタンパク質MPB64の1本鎖を用い、かつコントロールとして非結核菌群を用いた。結果として、MPB64の1本鎖に対して、3.7 × 10^5 copies/assay(すなわち4.2 × 10^3 copies/μL)の測定に成功し、また非結核菌群は測定に掛らなかった。すなわち予定通りに、 非増幅・迅速・簡便核酸測定法の開発に成功した。

  • 軟体動物の学習記憶機構におけるストレスと内因性カンナビノイド受容体の役割

    2016  

     View Summary

    &nbsp; 過度のストレスから解放されると、動物の学習成績が改善されるのか?この問題を神経生物学で永く利用されている軟体動物モノアラガイで調べた。ストレスからの解放はカンナビノイドの投与によって得た。ほ乳類の脳内には内在性カンナビノイドならびにその受容体が存在する。一方、無脊椎動物はストレスや学習の研究に十分利用可能であるが、それらの存在は不明であった。そこで軟体動物モノアラガイを用いて受容体の存在を調べたところ、ほ乳類と相同な受容体が見つかった、さらには学習行動やストレスが及ぼす影響に対して、カンナビノイド受容体のアゴニスト・アンタゴニストがどのように関与するのかを調べる実験も開始することができた。

  • 脳内インスリンは薬か?毒か?

    2016  

     View Summary

    脊椎動物でも無脊椎動物でも、その脳内でインスリンがはたらくことが、近年わかってきた。ただし、このインスリンが学習記憶機構に対して「増強」としてはたらくのか、または「減弱」としてはたらくのかは、不明な点が多い。本研究では、学習記憶研究で永年使用されてきている軟体動物モノアラガイを用いて、①インスリンのシグナルカスケードとセロトニンカスケードが長期記憶形成において拮抗的にはたらくことが明らかとなった。また、②転写因子CREBのシグナルカスケード、ならびにそれに続くCRTCのシグナルカスケードの研究を開始することができた。なお本研究は、同一課題にて特定課題(新任の教員等)でも研究が遂行された。

  • 脳内インスリンは薬か?毒か?

    2016  

     View Summary

    &nbsp; 脊椎動物でも無脊椎動物でも、その脳内でインスリンがはたらくことが、近年わかってきた。ただし、このインスリンが学習記憶機構に対して「増強」としてはたらくのか、または「減弱」としてはたらくのかは、不明な点が多い。本研究では、学習記憶研究で永年使用されてきている軟体動物モノアラガイを用いて、①インスリンのシグナルカスケードとセロトニンカスケードが長期記憶形成において拮抗的にはたらくことが明らかとなった。また、②転写因子CREBのシグナルカスケード、ならびにそれに続くCRTCのシグナルカスケードの研究を開始することができた。なお本研究は、同一課題にて特定課題Bでも研究が遂行された。

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Syllabus

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Committee Memberships

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    日本生物物理学会・副会長

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    Biophysical Society of Japan, Vice President