Machemer H
Arbeitsgruppe Zelluläre Erregungsphysiologie, Ruhr-Universität, Bochum, Germany.
Adv Space Res. 1996;17(6-7):11-20. doi: 10.1016/0273-1177(95)00607-g.
The archaic eukaryote unicellular microorganism, Paramecium, is propelled by thousands of cilia, which are regulated by modulation of the membrane potential. Ciliates can successfully cope with gravity, which is the phylogenetically oldest stimulus for living things. One mechanism for overcoming sedimentation is negative gravitaxis, an orientational response antiparallel to the gravity vector. We have postulated the existence of a negative gravikinesis in Paramecium, i.e. a modulation of swimming speed as a function of cellular orientation in space. With negative gravikinesis, an upward oriented cell actively augments the rate of forward swimming and depresses active locomotion during downward orientation. A brief outline of the gravikinesis hypothesis is given on a quantitative basis and experimental data are presented which have confirmed the major assumptions.
古老的真核单细胞微生物草履虫由数千根纤毛推动，这些纤毛通过膜电位的调节来控制。纤毛虫能够成功应对重力，重力是生物在系统发育上最古老的刺激因素。克服沉降的一种机制是负重力趋性，即一种与重力矢量方向相反的定向反应。我们推测草履虫中存在负重力运动，即游泳速度作为细胞在空间中取向的函数的调节。在负重力运动中，向上取向的细胞会积极提高向前游动的速度，而在向下取向时则会抑制主动运动。本文在定量基础上给出了重力运动假说的简要概述，并展示了证实主要假设的实验数据。
