Aerobic and anaerobic enzymatic activities of Calyptogena gallardoi (Vesicomyidae): a clam associated with methane cold seeps off Chile.

Calyptogena gallardoi is a recently described species of vesicomyid clam associated to the extensive gas-hydrate field reported for the Chilean margin along 35°S to 45°S. Enzymatic analysis in foot, gill and abductor muscle tissues of C. gallardoi collected in central-south Chile (~36°21′S 73°44′W), show high activities for malate dehydrogenase (MDH), strombine dehydrogenase (STRDH) and alanopine dehydrogenase (ALPDH) and a low activity of citrate synthase (CS) and ETS (electron transport system). Positive significant correlations (log–log scale) were found between enzymatic activities involved in anaerobic metabolism (MDH versus LDH and ALPDH versus STRDH), as well as between CS and opines dehydrogenases. The ratio MDH/LDH or any other opine dehydrogenase assayed was >> 1 in all tissues analysed. These results indicate that C. gallardoi is highly adapted to the harsh anaerobic conditions of marine chemosynthesis-based communities inhabiting a reduced environment.