Global depression in gene expression as a response to rapid thermal changes in vent mussels

Abstract

Hydrothermal vent mussels belonging to the genusBathymodiolusare distributed worldwide and dominate communities at shallow Atlantic hydrothermal sites. While organisms inhabiting coastal ecosystems are subjected to predictable oscillations of physical and chemical variables owing to tidal cycles, the vent mussels sustain pronounced temperature changes over short periods of time, correlated to the alternation of oxic/anoxic phases. In this context, we focused on the short-term adaptive response of mussels to temperature change at a molecular level. The mRNA expression of 23 genes involved in various cell functions of the vent musselBathymodiolus azoricuswas followed after heat shocks for either 30 or 120 min, at 25 and 30°C over a 48 h recovery period at 5°C. Mussels were genotyped at 10 enzyme loci to explore a relationship between natural genetic variation, gene expression and temperature adaptation. Results indicate that the mussel response to increasing temperature is a depression in gene expression, such a response being genotypically correlated at least for thePgm-1locus. This suggests that an increase in temperature could be a signal triggering anaerobiosis forB. azoricusor this latter alternatively behaves more like a ‘cold’ stenotherm species, an attribute more related to its phylogenetic history, a cold seeps/wood fall origin.