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.