S6-1.6 Thursday, Jan. 5 Environmental Stress Proteomics of the Mussel Mytilus TOMANEK, Lars; California State Univ., San Luis Obispo firstname.lastname@example.org
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 tolerates higher salinity levels than the native. Both, temperature and salinity changes have been hypothesized to contribute to the range shifts. Using proteomics, we were aiming to characterize the underpinnings of interspecific differences in thermal and salinity tolerance limits. We conducted several experiments: an acute heat stress experiments to 24°C, 28°C and 32°C, 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 hypo-saline (100%, 85% and 70% salinity) stress experiment for 4 h followed by a 0 h and 24 h recovery period. Using gill tissue, we applied 2D gel electrophoresis and tandem 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 response to hypo-salinity stress suggests oxidative-stress induced changes in energy metabolism in M. trossulus but not in M. galloprovincialis. Together, these results link ROS production to changes in metabolism that may contribute to setting tolerance limits.