(full paper is archived in the Miller Library)
Title: Temperature-induced gene expression in the mussel
Mytilus californianus
Student Author(s): Boomhower, Judson
Faculty Advisor(s): Somero, George
Pages: 27
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.