Updated on 2024/07/20


Faculty of Science and Engineering, School of Advanced Science and Engineering
Job title
Assistant Professor(without tenure)

Research Experience

  • 2022.09

    Waseda University   Department of Electrical Engineering and Bioscience   Assistant Professor

  • 2018.04

    Waseda University   Department of Electrical Engineering and Bioscience   Assistant

Education Background

  • 2012.04

    Waseda University   School of Advanced Science and Engineering   Department of Electrical Engineering and Bioscience  


    Waseda University   School of Science and Engineering   Department of Electrical Engineering and Bioscience  

Research Areas

  • Morphology and anatomical structure

Research Interests

  • Collective behavior

  • Cell motility

  • Cyanobacteria



  • Scattered migrating colony formation in the filamentous cyanobacterium, Pseudanabaena sp. NIES-4403.

    Hiroki Yamamoto, Yuki Fukasawa, Yu Shoji, Shumpei Hisamoto, Tomohiro Kikuchi, Atsuko Takamatsu, Hideo Iwasaki

    BMC microbiology   21 ( 1 ) 227 - 227  2021.08  [International journal]

     View Summary

    BACKGROUND: Bacteria have been reported to exhibit complicated morphological colony patterns on solid media, depending on intracellular, and extracellular factors such as motility, cell propagation, and cell-cell interaction. We isolated the filamentous cyanobacterium, Pseudanabaena sp. NIES-4403 (Pseudanabaena, hereafter), that forms scattered (discrete) migrating colonies on solid media. While the scattered colony pattern has been observed in some bacterial species, the mechanism underlying such a pattern still remains obscure. RESULTS: We studied the morphology of Pseudanabaena migrating collectively and found that this species forms randomly scattered clusters varying in size and further consists of a mixture of comet-like wandering clusters and disk-like rotating clusters. Quantitative analysis of the formation of these wandering and rotating clusters showed that bacterial filaments tend to follow trajectories of previously migrating filaments at velocities that are dependent on filament length. Collisions between filaments occurred without crossing paths, which enhanced their nematic alignments, giving rise to bundle-like colonies. As cells increased and bundles aggregated, comet-like wandering clusters developed. The direction and velocity of the movement of cells in comet-like wandering clusters were highly coordinated. When the wandering clusters entered into a circular orbit, they turned into rotating clusters, maintaining a more stable location. Disk-like rotating clusters may rotate for days, and the speed of cells within a rotating cluster increases from the center to the outmost part of the cluster. Using a mathematical modeling with simplified assumption we reproduced some features of the scattered pattern including migrating clusters. CONCLUSION: Based on these observations, we propose that Pseudanabaena forms scattered migrating colonies that undergo a series of transitions involving several morphological patterns. A simplified model is able to reproduce some features of the observed migrating clusters.

    DOI PubMed


  • Morphological and genome analysis of cluster forming cyanobacterium Pseudanabaena sp.

    Hiroki Yamamoto, Yuki Fukasawa, Yu Shoji, Tomohiro Kikuchi, Hiroaki Kobayashi, Yuu Hirose, Hideo Iwasaki

    11th European Workshop on the Biology of Cyanobacteria 

    Presentation date: 2020.09

    Event date:



Internal Special Research Projects

  • 糸状性バクテリアの運動集団形成に関係する遺伝子決定を目的とした形質転換系の確立

    2020   岩崎, 広瀬

     View Summary

     本課題は藍藻、Pseudanabaena sp. NIES-4403株が行う集団運動の機構を遺伝学的操作を通じて解明することを目的とした研究である。申請者は形質転換系の確立を目指して試行を行ったものの、形質転換株を得ることはできなかった。今後は試行を続けるとともに、形質転換の報告がある近縁種の利用などを検討中である。一方でロングリードシーケンサーを用いたゲノム情報の解読に成功し、既存の情報を併用することで完全なゲノム情報を現在構築中である。 この研究に関わる成果を2020年9月に国際会議11th EWBCで発表を行った。また、この株の形態学的に解析した結果を2020年8月にBMC Microbiologyに投稿し、2021年4月に受理された。