Enzymatic and Low-Molecular Weight Parts of Antioxidant Complex in Two Species of Black Sea Mollusks with Different Resistance to Oxidative Stress: Mytilus galloprovincialis Lam. and Anadara kagoshimensis (Tokunaga, 1906)

Abstract

We studied the specific features of the joint activity of the enzyme and low-molecular weight parts of the antioxidant (AO) complex in the tissues of two species of the Black Sea bivalve mollusks with different resistance to oxidative stress: a native species, the Mediterranean mussel Mytilus galloprovincialis Lam., and an invader, the ark clam Anadara kagoshimensis (Tokunaga, 1906). In the hepatopancreas and the gills and foot of mollusks, the activity of glutathione peroxidase (GP), glutathione reductase (GR), superoxide dismutase (SOD), catalase, and the level of reduced glutathione (GSH), as well as the contents of glucose, amino acids, and products that react with thiobarbituric acid (TBA-reactive products), have been analyzed. The enzyme part had a leading role in AO defense in the tissues of the Mediterranean mussel. This is indicated by higher activities of GP (hepatopancreas, gills) and SOD (hepatopancreas, foot) but a smaller content of GSH (gills, foot) as compared with ark clam. In ark clam tissues, the role of low-molecular weight part is significant, which is confirmed by the higher GSH level (gills, foot) in combination with the higher activity of GP (foot) and SOD and catalase (gills) than that observed in the Mediterranean mussel. Unlike the mussel, ark clam tissues showed a more effective joint activity of SOD, catalase, and glutathione system, which resulted in a significantly lower content of LPO products than that found in all of the studied Mediterraneanmussel tissues. These features of the joint activity of the enzyme and low-molecular weight parts of the AO complex of the Mediterranean mussel and ark clam largely determine the difference in the resistance to oxidative stress in the mollusks of these species. The results confirm the prevailing idea of the ark clam as one of the most competitive invaders as compared with native species; it has successfully mastered new biotopes in the Azov-Black Sea basin and has become an important component of benthic communities.