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Effects of clinorotation and microgravity on sweet clover columella cells treated with cytochalasin DThe cytoskeleton of columella cells is believed to be involved in maintaining the developmental polarity of cells observed as a reproducible positioning of cellular organelles. It is also implicated in the transduction of gravitropic signals. Roots of sweet clover (Melilotus alba L.) seedlings were treated with a microfilament disrupter, cytochalasin D, on a slowly rotating horizontal clinostat (2 rpm). Electron micrographs of treated columella cells revealed several ultrastructural effects including repositioning of the nucleus and the amyloplasts and the formation of endoplasmic reticulum (ER) whorls. However, experiments performed during fast clinorotation (55 rpm) showed an accumulation (but no whorling) of a disorganized ER network at the proximal and distal pole and a random distribution of the amyloplasts. Therefore, formation of whorls depends upon the speed of clinorotation, and the overall impact of cytochalasin D suggests the necessity of microfilaments in organelle positioning. Interestingly, a similar drug treatment performed in microgravity aboard the US Space Shuttle Endeavour (STS-54, January 1993) caused a displacement of ER membranes and amyloplasts away from the distal plasma membrane. In the present study, we discuss the role of microfilaments in maintaining columella cell polarity and the utility of clinostats to simulate microgravity.
Document ID
20040089443
Acquisition Source
Headquarters
Document Type
Reprint (Version printed in journal)
Authors
Hilaire, E.
(Kansas State Univ. NSCORT in Gravitational Biology, Manhattan 66506-4901, United States)
Paulsen, A. Q.
Brown, C. S.
Guikema, J. A.
Spooner, B. S.
Date Acquired
August 21, 2013
Publication Date
October 1, 1995
Publication Information
Publication: Physiologia plantarum
Volume: 95
Issue: 2
ISSN: 0031-9317
Subject Category
Life Sciences (General)
Funding Number(s)
CONTRACT_GRANT: NAGW-2328
CONTRACT_GRANT: NAGW-1197
Distribution Limits
Public
Copyright
Other
Keywords
manned
Non-NASA Center
short duration
Flight Experiment
NASA Center KSC
NASA Discipline Plant Biology
NASA Discipline Cell Biology
STS-54 Shuttle Project

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