Meeting Abstract
Increasing atmospheric temperatures significantly influence the physiological functions in aquatic organisms, particularly the marine invertebrates which are extremely susceptible to elevated temperature. In this study, we observed the effect of elevated temperatures (16, 22, 26, and 30°C for 1-week exposure) on the morphology as well as on the prooxidant and antioxidant homeostasis in gills and digestive glands of American oyster, Crassostrea virginica. Immunohistochemical analysis was performed to observe the expression of heat shock protein 70 (HSP70, an indicator of heat stress), dinitrophenyl (DNP, a biomarker of reactive oxygen species, ROS), nitrotyrosine protein (NTP, an indicator of reactive nitrogen species, RNS), catalase (CAT, an antioxidant), and superoxide dismutase (SOD, an antioxidant) in gills and digestive glands of oysters. Histological analysis showed an increase in mucus secretion, a common response to different stressors, with increasing temperature in both tissues along with the enlargement of lumens of digestive glands. Immunohistochemical analysis showed a significant increase of HSP70, DNP, and NTP protein expressions with elevated water temperature from 16 to 30°C, indicating rising temperatures induce thermal stress which leads to increased oxidative stress as well as nitrosative stress. Interestingly, the expression of CAT and SOD increased from 16 to 26°C in oyster tissues, however, a significant drop in expression of CAT and SOD was observed at 30°C which indicates that oyster tissues become defenseless against the attack of ROS and RNS at high temperature. Collectively, we conclude that elevated seawater temperature induces oxidative and nitrosative stresses which may trigger cellular apoptosis in American oyster.
