POLIN, M.R.; COSTANZO, J.P.; YI, S.-X.; LEE, R.E.; Miami Univ., Oxford, OH; Miami Univ., Oxford, OH; Miami Univ., Oxford, OH; Miami Univ., Oxford, OH: Levels of Cholesterol in Blood and Plasma Membrane in Response to Environmental Stress in the Hatchling Painted Turtle

Hatchling painted turtles (Chrysemys picta) commonly hibernate for many months inside their natal nests. The harsh nest environment requires that the turtles tolerate supercooling to low temperatures, episodes of somatic freezing, functional hypoxia induced by severe hypothermia, and desiccation. The aim of our preliminary study was to determine whether these conditions influence levels of cholesterol, which in many organisms plays an important role in membrane adaptation to stress. Plasma cholesterol level in the cold-acclimated hatchling painted turtle (10 �mol/ml) was similar to the levels found in hatchlings of other species, and, except for a 70% increase during dehydration, did not vary in response to the aforementioned stresses. Cholesterol content of erythrocyte membranes tended to increase in response to supercooling, somatic freezing, and dehydration over the level found in control turtles (9.1 �mol/mg protein). In contrast, the cholesterol level in membranes isolated from intestine (control turtles, 7.7 �mol/mg protein) showed no change, or decreased slightly, in response to these stresses. Reduced cholesterol was found in both types of plasma membrane isolated from anoxia-exposed turtles. Additional study is needed to determine how these changes affect membrane adaptation to stress. Supported by the NSF (IBN9817087) and Howard Hughes Summer Internship.