Meeting Abstract

P3.66  Monday, Jan. 6 15:30  Acclimatization in tadpoles of the Green frog (Rana clamitans) GRAY, K.T.; ESCOBAR, A.M.; MINEO, P.; SCHAEFFER, P.J.; BERNER, N.J.*; Sewanee: University of the South; Sewanee: University of the South; Miami University, Oxford, OH; Miami University, Oxford, OH; Sewanee: University of the South nberner@sewanee.edu

Acclimatization (or acclimation) is the process by which individual organisms vary their characteristics in response to some aspect or aspects of their environment, and is an important mechanism by which organisms respond to fluctuations in their surroundings. Modifications in characteristics brought on by natural seasonal temperature differences can offset the depressive effects of lower winter temperatures. Tadpoles of the Green frog (Rana clamitans) overwinter as tadpoles in some parts of their range, including locally in Sewanee, TN. Because they demonstrate escape behavior in the winter when disturbed, we hypothesized that Green frog tadpoles would demonstrate acclimatization in some commonly modified biochemical and behavioral characteristics. To test this hypothesis, we collected tadpoles in winter (January) and summer (June and July) in Lake Cheston, Sewanee, TN. We measured a number of acclimation parameters (enzyme activity, metabolic rate, and escape behavior) at local winter (8°C) and summer (26°C) temperature, and determined membrane phospholipid fatty acid composition in winter- and summer-collected tadpoles. Tadpoles showed no acclimatization in metabolic rate (O₂ consumption of winter- and summer-collected tadpoles were not significantly different when measured at the same temperature) while simultaneously demonstrating acclimatization in the activities of all metabolic enzymes tested (significantly higher activity in muscle homogenates from winter- than summer-collected tadpoles for cytochrome c oxidase, citrate synthase and lactate dehydrogenase). Data for escape behavior as well as membrane lipid composition will also be presented.