多くの”仮足”を巧みに使う有殻アメーバの動き方を解明～単細胞生物とは思えない精密な運動の仕組み～

2025-12-02 北海道大学,山形大学,富山大学,法政大学

基盤上を這うナベカムリの移動を横から見た様子:細胞体はキチン質の殻でおおわれており、腹側の一つの穴から複数の仮足(矢印・矢じり)を伸長させ、これらを巧みに用いることで移動する(スケール50 µm)。

<関連情報>

• https://www.hokudai.ac.jp/news/2025/12/post-2135.html
• https://www.hokudai.ac.jp/news/pdf/251202_pr.pdf
• https://www.jstage.jst.go.jp/article/pjab/advpub/0/advpub_pjab.102.001/_article

有殻アメーバ”ナベカムリ”の多仮足を用いた移動の統計・力学的解析 Statistical and mechanical analysis of multi-pseudopodial locomotion in a testate amoeba, Arcella sp.

Genta MATSUMOTO, Atsushi TANIGUCHI, Mami NOMURA, Satoshi SHIMANO, Jean-Paul RIEU, Katsuhiko SATO, Toshiyuki NAKAGAKI, Yukinori NISHIGAMI
Proceedings of the Japan Academy, Series B  Accepted: October 28, 2025
DOI:https://doi.org/10.2183/pjab.102.001

Abstract

Adherent eukaryotic cells typically exhibit amoeboid locomotion through actin polymerization and bleb-driven mechanisms. However, testate amoebae, which enclose their bodies within a shell, exhibit variation in these locomotion types. This study focused on Arcella, a representative testate amoeba that pulls its shell using multiple pseudopods extending from a single aperture on the ventral side. Arcella may be found in peatlands and freshwater, where it adapts its movement to various substrates. We characterized its movement on glass as well as hard, and soft gel substrates through detailed observation. The results indicated a higher randomness in motion on the soft gel, which was influenced by the pseudopodial elongation direction. Additionally, we evaluated the relationship between movement direction and traction stress. The dipole moment of the traction stress field determined the axis of motion, whereas quadrupole moments were correlated with forward and lateral movements. Although some relationships between multipole moments and velocity were shared with other cells, Arcella exhibited unique characteristics in its movement mechanism, which likely occurred due to its use of multiple pseudopods alongside its shell.