title: Cholesterol content of trout plasma membranes varies with acclimation temperature.
abstract: Involvement of cholesterol in thermally induced restructuring of biological membranes was investigated in several tissues of rainbow trout (Oncorhynchus mykiss). Cholesterol-rich plasma membranes (PM) were isolated from erythrocytes, liver, kidney, and gill of fish acclimated to 5 and 20 degrees C. Mean PM cholesterol-to-phospholipid molar ratios (C/P) from warm-acclimated animals were significantly higher than those of cold-acclimated fish in liver (0.26 vs. 0.18; P < 0.01), kidney (0.49 vs. 0.40; P < 0.02), and gill (0.66 vs. 0.60; P < 0.05); erythrocyte C/P did not differ significantly with acclimation temperature (0.28 vs. 0.25; P = 0.25). 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 PM C/P of trout tissues relative to corresponding data available for homeotherms also support a possible evolutionary relationship between cholesterol content and thermal adaptation of the PM.
authors.affiliation: Department of Zoology, Arizona State University, Tempe 85287-1501, USA.
authors.forename: J C
authors.initials: JC
authors.lastname: Robertson
authors.forename: J R
authors.initials: JR
authors.lastname: Hazel
mesh_terms: D000064:Acclimatization; D000818:Animals; D002462:Cell Membrane / Q000378:metabolism; D002784:Cholesterol / Q000378:metabolism*; D002851:Chromatography, High Pressure Liquid; D008563:Membrane Lipids / Q000378:metabolism; D017686:Oncorhynchus mykiss / Q000378:metabolism*; D010743:Phospholipids / Q000378:metabolism; D013696:Temperature
chemical_list: D008563:Membrane Lipids; D010743:Phospholipids; D002784:Cholesterol