Relaxation and activation of graviresponses in Paramecium caudatum

Richard Bräucker, Akira Murakami, Kazuko Ikegaya, Kenjiro Yoshimura, Keiichi Takahashi, Sigrun Machemer-Röhnisch, Hans Machemer

研究成果: Article査読

19 被引用数 (Scopus)


The kinetics of gravitaxis and gravikinesis in Paramecium caudatum were investigated by employing (1) step transitions from normal gravity (1 g) to weightlessness (microgravity) and (2) turns of the experimental chambers from the horizontal to the vertical position at 1 g. The transition to microgravity left existing cell orientations unchanged. Relaxation of negative gravitaxis under microgravity took longer than 10 s and may be described by the time constant of the decay of orientation coefficients. Gravitaxis was started at 1 g by turning the experimental chamber from a horizontal to a vertical position, Gravitaxis activated rapidly during the turning procedure and relaxed to an intermediate level after the turning had stopped. Gravity-induced regulation of swimming speed (gravikinesis) at 1 g had reached a steady state after 1 min; at this point, gravikinesis counteracted the effects of sedimentation (negative gravikinesis). A step transition to microgravity initially reversed the sign of the gravikinesis (positive gravikinesis). The relaxation of this kinetic response was not completed during 10s of microgravity. The data suggest that gravikinesis is functionally unrelated to gravitaxis and is strongly affected by the rate of change in acceleration. We present a model explaining why gravikinesis reverses sign upon the onset of a step from 1 g to microgravity.

ジャーナルJournal of Experimental Biology
出版ステータスPublished - 1998 7月

ASJC Scopus subject areas

  • 生態、進化、行動および分類学
  • 生理学
  • 水圏科学
  • 動物科学および動物学
  • 分子生物学
  • 昆虫科学


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