spacer gif spacer gif spacer gif spacer gif spacer gif
QUICK SEARCH:   [advanced]


spacer gif
     Home     Help     Feedback     Subscriptions     Archive     Search     Table of Contents    

This Article
Right arrow Full Text (PDF)
Right arrow References
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Services
Right arrow Email this article to a friend
Right arrow Similar articles in this journal
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Right arrow reprints & permissions
Citing Articles
Right arrow Citing Articles via HighWire
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Braucker, R.
Right arrow Articles by Machemer, H.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Braucker, R.
Right arrow Articles by Machemer, H.

Journal of Experimental Biology, Vol 201, Issue 14 2103-2113, Copyright © 1998 by Company of Biologists

JOURNAL ARTICLES

Relaxation and activation of graviresponses in Paramecium caudatum

R Braucker, A Murakami, K Ikegaya, K Yoshimura, K Takahashi, S Machemer-Rohnisch and H Machemer
Arbeitsgruppe Zellulare Erregungsphysiologie, Fakultat fur Biologie, Ruhr Universitat, D-44780 Bochum, Germany.

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 10 s 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.


This article has been cited by other articles:


Home page
 Biophys. JHome page
K. Guevorkian and J. M. Valles Jr.
Aligning Paramecium caudatum with Static Magnetic Fields
Biophys. J., April 15, 2006; 90(8): 3004 - 3011.
[Abstract] [Full Text] [PDF]

Home page
 Plant Physiol.Home page
W. Schmidt and P. Galland
Optospectroscopic Detection of Primary Reactions Associated with the Graviperception of Phycomyces. Effects of Micro- and Hypergravity
Plant Physiology, May 1, 2004; 135(1): 183 - 192.
[Abstract] [Full Text] [PDF]

Home page
 J. Exp. Biol.Home page
U Nagel and H Machemer
Physical and physiological components of the graviresponses of wild-type and mutant Paramecium Tetraurelia
J. Exp. Biol., January 3, 2000; 203(6): 1059 - 1070.
[Abstract] [PDF]

Home page
 FASEB J.Home page
R. HEMMERSBACH and D.-P. HADER
Graviresponses of certain ciliates and flagellates
FASEB J, May 1, 1999; 13(9001): 69 - 75.
[Abstract] [Full Text] [PDF]


© The Company of Biologists Ltd 1998