(full paper is archived in the Miller Library)
Title: Temperature-induced gene expression in the mussel
Student Author(s): Boomhower, Judson
Faculty Advisor(s): Somero, George
Location: Final papers biology 175H
Date: June 2004
Abstract: Organisms occupying rocky intertidal habitats are exposed to extreme temperature fluctuations. Given the pervasive effects of temperature on physiological function, large changes in gene expression would be expected in these organisms as temperature varies. Gene expression at elevated temperatures was investigated in vitro using gill tissue from the mussel Mytilus californianus. Tissues were exposed to temperatures between 20.1 and 36.2° C, and differential expression was evaluated using a 4224 cDNA Mytilus microarray. At 33° C, mRNA levels for hsp70 were induced 60 to 110-fold compared to the control temperature. Several other genes coding for proteins involved in protein folding (hsp20), degradation of denatured polypeptides (sequestosome 1), apoptosis (fos-related antigen 2), and other activities appeared to be induced with elevated temperature. mRNA levels for most genes were greatly reduced at 36.2° C, suggesting a deleterious effect of temperature on gene expression (either retardation of induction or greater degradation of mRNA) at this temperature. Simulated mussel body temperatures in excess of 41° C were recorded at the collection site. Thus, habitat temperatures may occasionally exceed the thermal tolerance limits of the animal. This is likely to affect the ecology and biogeography of the species.