@inproceedings{oai:jaxa.repo.nii.ac.jp:00013918,
 author = {平嶋, 未絵 and 森脇, 梓 and 最上, 善広 and 馬場, 昭次 and Hirashima, Mie and Moriwaki, Azusa and Mogami, Yoshihiro and Baba, Shoji A.},
 book = {宇宙利用シンポジウム　第19回　平成14年度, Space Utilization Research: Proceedings of the Nineteenth Space Utilization Symposium},
 month = {Feb},
 note = {Gravitactic behaviors of ciliates are performed by the mechanisms orienting the fore-aft axis of the cell to the gravity vector. Physiological and mechanical biases have been postulated to the orientation mechanisms; physiological reorientation is thought to be derived from the results of the cellular mechanical sensation (Ooya et al., 1992), and mechanical ones from the mechanical properties of the swimming cell. Mogami et al. (2001) demonstrated that the mechanical reorientation of Paramecium is largely due to the geometrical fore-aft asymmetry of the cell, which leads to the anterior shift of the hydrodynamic reaction center relative to those of gravity and buoyancy. The morphology-dependent mechanical orientation was clearly demonstrated by the evidence that immobilized cells oriented upwards during sinking in the hypodensity medium (control medium of density lower than that of the organism) whereas downwards during floating in the hyperdensity medium (of density higher than that of the organism). In order to investigate the contribution of the mechanical mechanism working in the swimming cells, the gravitactic behaviors of Paramecium caudatum and Tetrahymena pyriformis in hyperdensity and hypodensity media were compared. Both ciliates showed positive gravitactic migration in hyperdensity media immediately after they were allowed to swim freely in the vertical direction, whereas they showed ordinary negative gravitaxis in hypodensity media. This result indicates that the morphology-dependent mechanical orientation functions as the actual mechanical bias in swimming ciliates., 資料番号: AA0045438011},
 pages = {33--35},
 publisher = {宇宙科学研究所, The Institute of Space and Astronautical Science (ISAS)},
 title = {繊毛虫の重力走性行動における形態依存的重力配向特性},
 year = {2003}
}