title: Semi-circular microgrooves to observe active movements of individual Navicula pavillardii cells.
abstract: We performed a trajectory analysis of movements of Navicula pavillardii diatom cells that were confined to semi-circular microgrooves with several different curvature radii. Using the semi-circular micropattern, we succeeded in observing change of velocity of the same cell before and after the stimulation by N,N-dimethyl-p-toluidine (DMT). Because the looped grooves had longer contour length than straight grooves, it was effective to achieve the long term observation of the stimulated active cells. Although average velocity of 150 cells was significantly increased with DMT, the maximum velocity (19 μm/s) of the cells was not increased after the DMT injection. This may suggest that existence of the mechanical limit of the velocity of the diatom cells. Secondly, trajectories of individual cell movements along the walls of the semi-circular microgrooves were analyzed in detail. As a result, the velocity of the cells was not affected by the curvature radii of the grooves although the trajectories indicated an obvious restriction of area of the cell motion. This suggests that the surface of the diatom is effective in minimizing the frictional force between the cell body and the wall of a groove. Finally, a simple model of cell motion in the semi-circular groove was proposed to clarify the relationships among the forces that determine cell movement.
authors: Department of Physics, Faculty of Science, Tokyo University of Science, 1-3 Kagurazaka, Shinjuku, Tokyo 162-8601, Japan. meicun2006@163.com
authors: Kazuo
authors: K
authors: Umemura
authors: Takahiro
authors: T
authors: Haneda
authors: Masashi
authors: M
authors: Tanabe
authors: Akira
authors: A
authors: Suzuki
authors: Yoshikazu
authors: Y
authors: Kumashiro
authors: Kazuyoshi
authors: K
authors: Itoga
authors: Teruo
authors: T
authors: Okano
authors: Shigeki
authors: S
authors: Mayama
mesh_terms: D017377:Diatoms / Q000187:drug effects* / Q000502:physiology*; D008124:Locomotion / Q000187:drug effects*; D008828:Microbiological Techniques / Q000379:methods*; D018715:Microscopy, Video / Q000379:methods; D014052:Toluidines / Q000378:metabolism
chemical_list: D014052:Toluidines; C015835:dimethyl-4-toluidine