Hemmersbach R, Krause M, Bräucker R, Ivanova K
Institute of Aerospace Medicine, DLR, Cologne, Germany.
Adv Space Res. 2005;35(2):296-9. doi: 10.1016/j.asr.2005.03.024.
Ciliates represent suitable model systems to study the mechanisms of graviperception and signal transduction as they show clear gravity-induced behavioural responses (gravitaxis and gravikinesis). The cytoplasm seems to act as a "statolith" stimulating mechanosensitive ion channels in the cell membrane. In order to test this hypothesis, electrophysiological studies with Stylonychia mytilus were performed, revealing the proposed changes (de- or hyperpolarization) depending on the cell's spatial orientation. The behaviour of Paramecium and Stylonychia was also analyzed during variable acceleration conditions of parabolic flights (5th German Parabolic Flight Campaign, 2003). The corresponding data confirm the relaxation of the graviresponses in microgravity as well as the existence of thresholds of graviresponses, which are found to be in the range of 0.4xg (gravikinesis) and 0.6xg (gravitaxis).
由于纤毛虫表现出明显的重力诱导行为反应（趋重力性和重力运动），它们是研究重力感知和信号转导机制的合适模型系统。细胞质似乎充当“平衡石”，刺激细胞膜中的机械敏感离子通道。为了验证这一假设，对贻贝棘尾虫进行了电生理研究，结果显示根据细胞的空间取向会出现所提出的变化（去极化或超极化）。在抛物线飞行的可变加速度条件下（2003年第五届德国抛物线飞行活动），还分析了草履虫和贻贝棘尾虫的行为。相应的数据证实了微重力下重力反应的松弛以及重力反应阈值的存在，发现这些阈值在0.4xg（重力运动）和0.6xg（趋重力性）范围内。
