Parameters of Energy Metabolism and Adenylate System in Mytilus galloprovincialis Tissues under Moderate Hypoxia.

The effect of moderate hypoxia on the processes of energy metabolism was studied in the tissues (gills, hepatopancreas) of the Mediterranean mussel Mytilus galloprovincialis (Lamarck, 1819). The mollusks was kept at 6.8–6.9 mg O2 L–1 (control group) or 1.9–2.0 mg O2 L–1 (experimental group). In both cases, water temperature was 22 ± 1°C, salinity 17–18‰, exposure time 72 h. Dissolved oxygen content in water was lowered by nitrogen bubbling for 4–5 h. Under moderately hypoxic conditions, a complex of biochemical reactions aimed at retaining the baseline energy status developed in the mussel tissues. While aerobic processes were clearly on the decline, as evidenced by a decrease in succinate dehydrogenase (SDH) activity, anaerobic glycolysis intensified. Aldolase and malate dehydrogenase (MDH) activities, as well as tissue pyruvate level, increased. Both lactate dehydrogenase (LDH) activity and lactate levels in mussel tissues remained unchanged. The state of the M. galloprovincialis adenylate system was comprehensively characterized. The tissue content of the ATP fraction remained at the level of control values, reflecting an adaptive trend in the reorganization of tissue metabolism. The ability of the hepatopancreas to accumulate ADP and AMP fractions from the circulatory systems under conditions of experimental hypoxic load was noted for the first time. Presumably, this may largely explain the increase in the pool of adenylates and the decrease in the adenylate energy charge in this organ. It was concluded that the reorganization of carbohydrate metabolism in M. galloprovincialis under moderately hypoxic conditions allows the mussel to retain the energy status of its tissues and, therefore, to populate challenging (hypoxic) waters. [ABSTRACT FROM AUTHOR]