48.2 Saturday, Jan. 5 Molecular and biochemical observations of Mytilus californianus under constant submergence CONNOR, K.M.*; GRACEY, A.Y.; Univ. of California, Irvine; Univ. of Southern Califronia email@example.com
The mussel Mytilus californianus reside predominantly in the intertidal zone, a fluctuating environment at the interface of the terrestrial and marine biomes. However, cryptic populations have been found occupying subtidal regions offshore, which raise questions about what physiological mechanisms allow M. californianus to thrive in both environments. As a sessile species M. californianus encounters hourly, daily and seasonal fluctuations in oxygen, temperature, salinity and nutrient availability as a consequence of tidal and climate processes; whereas, these same physical and biological factors are comparatively more stable in subtidal environments. In order to investigate the link between intertidal and subtidal physiology, we performed transcript and metabolite screens of mussels held under constant submergence and compared the results to our previously published screens of mussels in a simulated intertidal environment. Specifically, submerged mussels were observed to exhibit either an open or closed valve state corresponding to periods of active cardiac activity and bradycardia respectively, and gill tissue was sampled from individuals exhibiting both states. Enrichment analysis of significantly expressed genes revealed that genes up-regulated in mussels exhibiting bradycardia and active activity were enriched for genes expressed during the simulated low and high tide respectively. A metabolomics screen revealed elevated levels of succinate, malate and alanine in mussels exhibiting bradycardia which suggested the activation of anaerobic pathways that are known to be induced during aerial exposure. Additionally, we observed higher levels of carnitine-conjugate intermediates of the fatty acid derivatives and branched-chain amino acid (BCKA) catabolism.