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Hydrostatic factors affect the gravity responses of algae and rootsThe hypothesis of Wayne et al. (1990) that plant cells perceive gravity by sensing a pressure differential between the top and the bottom of the cell was tested by subjecting rice roots and cells of Caracean algae to external solutions of various densities. It was found that increasing the density of the external medium had a profound effect on the polar ratio (PR, the ratio between velocities of the downwardly and upwardly streaming cytoplasm) of the Caracean algae cells. When these cells were placed in solutions of denser compound, the PR decreased to less than 1, as the density of the external medium became higher than that of the cell; thus, the normal gravity-induced polarity was reversed, indicating that the osmotic pressure of the medium affects the cell's ability to respond to gravity. In rice roots, an increase of the density of the solution inhibited the rate of gravitropism. These results agree with predictions of a hydrostatic model for graviperception.
Document ID
19920056522
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
Authors
Staves, Mark P.
(NASA Headquarters Washington, DC United States)
Wayne, Randy
(NASA Headquarters Washington, DC United States)
Leopold, A. C.
(Cornell University Ithaca, NY, United States)
Date Acquired
August 15, 2013
Publication Date
February 1, 1991
Publication Information
Publication: Physiologist, Supplement
Volume: 34
Issue: 1, Fe
ISSN: 0031-9376
Subject Category
Life Sciences (General)
Accession Number
92A39146
Distribution Limits
Public
Copyright
Other

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