Meeting Abstract
42.5 Monday, Jan. 5 The role of HSP70 expression in locomotion – Reduced sprint speeds after heat stress in Sceloporus occidentalis. MCMILLAN, D.M.*; REES, B; IRSCHICK, D; UMass Amherst; University of New Orleans; UMass Amherst mcmillan@bio.umass.edu
The Western fence lizard, Sceloporus occidentalis is a geographically widespread lizard occurring throughout the western United States across many diverse thermal environments, and can experience potentially stressful temperatures in these natural habitats. During these periods of temperature stress, metabolic enzymes become completely or partially denatured, losing the ability to function and limiting the energy production capabilities of the cell. The production of molecular chaperones, specifically heat shock proteins (Hsps) can aid in the recovery from periods of thermal stress by repairing denatured proteins to their functional state. However, this protection consumes metabolic energy which may be diverted from other organismal functions such as locomotion. Locomotor ability, especially sprint speed, is an important determinant of predator escape ability in lizards and is greatly affected by body temperature. The production of Hsps during periods of thermal stress may reduce the metabolic energy available for locomotion and therefore may increase the susceptibility of an individual to predation. For this study, we measured sprint speeds in recently captured S. occidentalis individuals from four populations during June 2007 and June 2008 before and after exposure to a thermal stress (or control temperature). After sprint trials we collected muscle tissue to quantify expression levels of Hsp70, one of the heat shock proteins. Lizard from all sites showed a decrease in sprint speed as a result of the heat stress and sprint speed was inversely related to Hsp70 expression. These results, along with the environmental variation in temperature at our sites indicate the potential for natural selection to act within these populations and may lead to populations of S. occidentalis becoming locally adapted to environmental temperature.
