Meeting Abstract

46.4  Saturday, Jan. 5  Environmental Stress Proteomics of Blue Mussel (Genus Mytilus) Congeners TOMANEK, L; California Polytechnic State University

The warm-adapted Mediterranean blue mussel species Mytilus galloprovincialis invaded southern California during the last century and has since replaced the cold-adapted native M. trossulus from its southern range, possibly due to climate change. Furthermore, M. galloprovincialis is more sensitive to lower salinity levels than the native. Both, temperature and salinity changes have been hypothesized to contribute to the range shifts and limits. Using proteomics, we characterized the underpinnings of interspecific differences in thermal and salinity tolerance limits. We conducted several experiments: an acute heat stress experiments to 24ºC, 28ºC and 32ºC, followed by a 24 h recovery at 13°C; a 4-week long temperature acclimation (7°C, 13°C and 19°C) experiment and an acute hyposaline (35, 29.8 and 24.5 psu seawater) exposure for 4 h followed by a 24 h recovery. Using gill tissue, we applied 2D gel electrophoresis and mass spectrometry to separate and identify proteins. The results suggest that acute heat stress triggers a shift from pro-oxidant NADH- to anti-oxidant NADPH-producing pathways to reduce the production of reactive oxygen species (ROS) and increase the cell’s capacity for ROS scavenging. Temperature acclimation showed that M. trossulus induces molecular chaperones at 19°C. Cold acclimation increased oxidative stress proteins and molecular chaperones in both congeners, although more so in M. galloprovincialis, suggesting a ROS-induced challenge to protein homeostasis at lower temperatures. The responses to hypo-salinity stress suggest that M. galloprovincialis is able to respond to 29.8 psu but not to 24.5 psu, in contrast to the native M. trossulus, which can respond to both. The results suggest that increased ROS production correlates with metabolic depression and reduced protein synthesis in all three treatments.