Meeting Abstract

P3.210  Sunday, Jan. 6  Effect of diet lipids on measures of seasonal acclimation in the Eastern red spotted newt (Notophthalmus viridescens viridescens) EMERSON, S.E.*; MORRIS, T.A.; BERNER, N.J.; Sewanee: University of the South; Sewanee: University of the South; Sewanee: University of the South nberner@sewanee.edu

Eastern red spotted newts are active in the winter. Our previous work shows that they acclimate enzyme activity, metabolic rate, behavioral thermoregulation, and membrane phospholipid fatty acid (FA) composition in skeletal muscle seasonally. We have also shown that membrane FA composition affects cytochrome c oxidase (CCO) activity; a more polyunsaturated membrane leads to higher CCO activity, as CCO is a membrane-bound enzyme. We tested the hypothesis that the change in membrane FA composition also drives the acclimatory changes in metabolic rate and behavioral thermoregulation. Newts were maintained in the laboratory at 25°C, 12:12 L:D, and three groups of newts were fed three different diets featuring three different types of lipids: saturated FAs (SFA); monounsaturated FAs (MUFA); and ω-3 polyunsaturated FAs (PUFA). After feeding the newts these diets for ten weeks, we determined their preferred cloacal temperature in a thermal gradient, and their standard metabolic rates (SMR, measured as oxygen consumption after one week of food deprivation) at 25 and 8°C. The preferred cloacal temperature of newts fed the high SFA diet was significantly higher (p = 0.008) than that of newts fed the high PUFA diet, and the newts fed a high MUFA diet had an intermediate preferred cloacal temperature. In addition, at 25°C newts fed the high PUFA diet had the highest SMR, significantly higher than the newts fed the SFA diet (p = 0.012). Newts fed the high MUFA diet had an intermediate SMR. At 8°C SMR did not vary with diet. Thus, the high PUFA diet led to other changes that are also indicative of winter acclimation (lower preferred cloacal temperature and higher SMR) suggesting that membrane composition plays an important role in winter acclimation in this species.