Tissue Metabolism and the State of the Antioxidant Complex in the Black Sea Mollusks Anadara kagoshimensis (Tokunaga, 1906) and Mytilus galloprovincialis Lamarck, 1819 with Different Tolerances to Oxidative Stress

The contents of amino acids and glucose, the activity of alanin aminotransferase (ALT), aspartate aminotransferase (AST), and the AO enzymes superoxide dismutase (SOD), catalase, glutathione peroxidase (GP), and glutathione reductase (GR), as well as the level of reduced glutathione (GSH) and TBA-reactive products, were investigated in the hepatopancreas, gills, and the foot of Black Sea bivalve mollusks: the blood cockle Anadara kagoshimensis (Tokunaga, 1906) (Bivalvia: Arcidae) and the mussel Mytilus galloprovincialis (Lamarck, 1819) (Bivalvia: Mytilidae) with their different tolerances to oxidative stress. Higher contents of glucose in the hepatopancreas and the foot and amino acids in the foot and a higher activity of AST in the gills were found in the mussel, which is relatively tolerant to hypoxia. Compared to blood cockle, mussels showed a higher GP and GR activity in hepatopancreas, GP activity in gills, and SOD activity in hepatopancreas and foot against the background of a higher content of TBA-reactive products in all studied tissues. A high content of amino acids was determined in the hepatopancreas and the gills of the blood cockle, which had a high tolerance to low oxygen. The activity of the ALT and AST enzymes in the foot and the activity of the ALT enzyme in the gills were higher in the blood cockle tissues than in the mussel tissues. This can be connected with more intensive processes of deamination and re-amination of amino acids in the cockle than in the mussel. The blood cockle had higher GP activity and GSH content in the foot and higher activity of SOD, catalase, and GR, as well the GSH level in the gills with a lower content of TBA products. The revealed peculiarities of the AO complex reflect adaptations of the mollusks to the oxygen regime in their habitat on the basis of specific peculiarities of their carbohydrate–protein metabolism.