Cholesterol content of trout plasma membranes varies with
acclimation temperature.
Robertson, John C., and Jeffrey R. Hazel.
Dept. of Zoology, Arizona State University, Tempe, AZ 85287
-1501
APStracts 2:0159R, 1995.
Involvement of cholesterol in thermally-induced restructuring of
biological membranes was investigated in several tissues of rainbow
trout (Oncorhynchus mykiss). Cholesterol-rich plasma membranes (PMs)
were isolated from erythrocytes, liver, kidney and gill of fish
acclimated to 5 C and 20 C. Mean PM cholesterol:phospholipid (C:P)
molar ratios from warm-acclimated animals were significantly higher
than those of cold-acclimated fish in liver (0.26 vs. 0.18; p < .01),
kidney (0.49 vs. 0.40; p < .02) and gill (0.66 vs. 0.60; p < .05);
erythrocyte C:P ratios did not differ significantly with acclimation
temperature (0.28 vs. 0.25; p = .25). In light of the ordering
effects of cholesterol on fluid-phase membranes, these results are
consistent with a role for cholesterol in the homeoviscous response
of some poikilotherm PMs. Tissue differences in both PM cholesterol
levels and the magnitude of thermally-evoked cholesterol changes may
reflect tissue-specific membrane functions. Lower plasma membrane C:P
ratios of trout tissues relative to corresponding data available for
homeotherms also supports a possible evolutionary relationship
between cholesterol content and thermal adaptation of the PM.
Received 20 January 1995; accepted in final form 5 June 1995.
APS Manuscript Number R46-5.
Article publication pending Am. J. Physiol. (Regulatory Integrative
Comp. Physiology).
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 6 July 1995.