The ribbed mussel (Mytilus californianus) occurs in the in the rocky intertidal zone along the Pacific coast of North America where it experiences greatly varying environmental conditions in terms of temperature and hypoxia, stressors that are known to induce oxidative stress. It has been hypothesized that while under acute heat stress, related Mytilus congeners undergo a shift in redox potential through the reduction of NADH fueled respiration pathways to the production of the reducing agent NADPH as a potential defensive mechanism against the production of reactive oxygen species. In addition, it has been hypothesized that sirtuins (a family of NAD-dependent deacetylases) might be involved in the regulation of this metabolic transition. To test the latter hypothesis, we used a discovery approach to analyze the proteomic response of this species to varying concentrations of menadione and suramin. Menadione is a cytotoxic agent that can induce apoptosis through the elevated production of peroxide and superoxide radicals while suramin is an effective inhibitor of sirtuin activity. Gill tissue was exposed to these compounds in filtered seawater for 8 h, followed by a 24 h recovery period under constant aeration. Tissues were homogenized and prepared for 2D-gel electrophoresis. Following separation, protein expression patterns suggested that the action of suramin affects a third of the changes in protein abundance during menadione-induced oxidative stress. These results prove that sirtuin activity (protein deacetylation) affects the cell’s response to oxidative stress. We are now identifying the proteins with tandem mass spectrometry and an expressed sequence tag library specific to Mytilus.



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