Influence of salinity on 3H-serine metabolism. Study of 3H-serine incorporation into lipids of the chinese crab Eriocheir sinensis

Abstract 1. 1. 3 H-serine incorporation into phospholipids isolated from hemolymph, hepatopancreas, gills and muscle was determined for chinese crab Eriocheir sinensis maintained in media of extreme salinities. 2. 2. 3 H-serine was mainly incorporated into phospholipids of hepatopancreas and gills. 3. 3. Decarboxylation of PS to PE occurs in these tissues. In addition, successive N -methylation of PE to PC takes place in hepatopancreas. The PS→PE→PC conversion was strongly activated when crabs were transferred from fresh water to sea-water. 4. 4. The roles of PS metabolism and of the N -methylation pathway of PE to PC in osmoregulation by these crabs are discussed.