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Gravity and positional homeostasis of the cellThe effect of gravity upon cytoplasmic aggregates of the size present in eggs and upon cells is investigated. An expression is developed to describe the tendency of torque to rotate the egg and reorganize its constituents. This expression provides the net torque resulting from buoyancy and gravity acting upon a dumbbell-shaped cell, with heavy and light masses at either end and floating in a medium. Torques of approximately 2.5 x 10 to the -13th to 0.85 dyne-cm are found to act upon cells ranging from 6.4 microns to 31 mm (chicken egg). It is noted that cells must expend energy to maintain positional homeostasis against gravity, as demonstrated by results from Skylab 3, where tissue cultures used 58 percent more glucose on earth than in space. The implications for developmental biology, physiology, genetics, and evolution are discussed. It is argued that at the cellular and tissue levels the concept of gravity receptors may be unnecessary.
Document ID
19830060826
Document Type
Reprint (Version printed in journal)
Authors
Nace, G. W. (Michigan, University Ann Arbor, MI, United States)
Date Acquired
August 11, 2013
Publication Date
January 1, 1983
Publication Information
ISSN: 0273-1177
Subject Category
LIFE SCIENCES (GENERAL)
Funding Number(s)
CONTRACT_GRANT: NAGW-29
CONTRACT_GRANT: NAS2-10945
Distribution Limits
Public
Copyright
Other