Mitochondrial membrane composition of two arctic marine bivalve mollusks, Serripes groenlandicus and Mya truncata

The phospholipid and fatty acid composition of gill mitochondria membranes from two Arctic marine bivalve mollusks, Mya truncata and Serripes groenlan dicus, were examined. These animals were collected from the Arctic Ocean, w here waters remain below 0 degrees C throughout the year. In both species, the primary membrane phospholipids were phosphatidylcholine, and phosphatid ylethanolamine. Although a low ratio of bilayer-stabilizing phospholipids t o bilayer-destabilizing phospholipids is frequently associated with cold ac climation in temperate species, this ratio is very different between the tw o species. The monounsaturated fatty acid 20:1 was abundant in the membrane s of both Arctic species equaling 13.0% of the fatty acid composition in S. groenlandicus, and 17.7% in M. truncata. Polyunsaturated fatty acids were relatively low in the Arctic species, equaling 35.9% of total membrane fatt y acids compared to that of temperate zone mollusks. It is suggested that m onoenes are common in the tissues of Arctic species since they play a role in maintaining membrane function at subzero temperatures.