Meeting Abstract
P3.56 Wednesday, Jan. 6 Cadmium exposure affects metabolic responses to acute temperature rise in eastern oysters Crassostrea virginica BAGWE, R.*; SOKOLOVA, I.M.; University of North Carolina at Charlotte, Charlotte, NC; University of North Carolina at Charlotte, Charlotte, NC rbagwe@uncc.edu
Cadmium (Cd) and elevated temperatures are common stressors in estuarine environments affecting intertidal mollusks such as oysters. Sublethal Cd exposure raises metabolic demand of oysters, that (according to the concept of oxygen-limited thermal tolerance) can lead to a downward shift of the critical temperature of aerobic metabolism and restrict thermal tolerance limits of the organism. We tested this hypothesis by determining the onset of anaerobic metabolism, changes in the cellular energy budget and the extent of oxidative damage during acute temperature rise (from 20°C to 36°C) in eastern oysters Crassostrea virginica under control conditions and Cd exposure (50 µg Cd L-1 for 30 days). In control oysters, levels of anaerobic end products (L-alanine, acetate and succinate) increased at 24 °C and above suggesting the critical temperature (Tc) of ca. 24 °C. In contrast, in Cd exposed oysters there was no accumulation of anaerobic end products during acute warming despite tissue hypoxemia indicating that Cd inhibits anaerobic pathways. There was a significant transient increase in ATP levels 24°C in control but not in Cd-exposed oysters; however, ATP levels were not significantly depleted even at the highest tested temperature (36°C) in either group. Elevated temperature elicited an increase of oxidative damage to proteins, which was similar in control and Cd-exposed groups, whereas lipid peroxidation was not affected by temperature or Cd. These data suggest that Cd exposure may delay or prevent the temperature-induced transition to anaerobiosis in oysters that may have important implications for determining Tc and for tolerance to the environmental conditions where survival solely depends on anaerobic metabolism (e.g. during oxygen deprivation). Supported by NSF and UNC Charlotte.
