Meeting Abstract
Intertidal mussels of the genus Mytilus experience extreme shifts in abiotic conditions, specifically oxygen partial pressure, due to tidal fluctuations. We therefore hypothesized that acclimation to a tidal rhythm, as opposed to a subtidal rhythm, preconditions the proteome of the California mussel (Mytilus californianus) to respond differently to anoxia, as low oxygen may occur during prolonged low tides. To investigate how entrainment affects the proteomic response to anoxia, mussels were acclimated to tidal and subtidal conditions with a 12-hour photoperiod to mimic natural circadian rhythms. Following a 4-week acclimation, mussels either continued to receive the acclimation conditions (control) or were exposed to 100% nitrogen gas (anoxia). Gill tissue was extracted at 0, 6, and 72 hr. We used gel-based proteomic analysis and identification with mass spectrometry to examine changes in global protein abundance. Tidally-entrained mussels showed lower abundances of superoxide dismutase during anoxia in comparison to mussels acclimated to subtidal conditions, indicating greater levels of oxidative stress in the latter. These differences were accompanied by changes in the abundances of several chaperones of the endoplasmic reticulum (GRP78, PDI), which are involved in the formation of disulfide bonds. Subtidally-entrained mussels also showed higher abundances of NADPH-producing proteins which may help scavenge reactive oxygen species during anoxia. Finally, the abundance of the oxygen-sensing protein aconitase was significantly higher in tidally-entrained mussels. Our results implicate that mussels acclimated to different tidal conditions differ greatly in the cellular processes that are activated in response to acute anoxia stress.
