The component fatty acids of the lipids of some species of marine and freshwater molluscs

Abstract

The component fatty-acid patterns of the triglycerides, phospholipids and, in some instances, sterol esters of a number of aquatic molluscs have been determined. The species examined include several of marine origin(Chlamys opercularis, Crepidula fornicata, Mytilus edulis, Neptunea antiqua, Patella vulgataandPecten maximus)and one of freshwater origin(Anodontasp.). The marine species contained considerable proportions of highly unsaturated acids of the C and C series (eg. 20:5 and 22:5) which are characteristic of the lipids of most aquatic plants and animals. In general, the relative percentages of 18:1,20:1 and 20:4 (5,8,11,14) were greater in the lipids of the marine gastro-pods than in those of the pelecypods. The differences between the fatty-acid distributions of theAnodontasp. and marine members of the pelecypoda are analogous to those existing between other freshwater and marine animals. Studies were made of the seasonal variations in the relative proportions and fatty-acid compositions of the triglycerides and phospholipids inP. vulgata.The relative proportions of 20:4 (5,8,11,14) and 20:5 in the triglycerides rose abruptly from minimum values in January to maximum values in March and thereafter declined slowly. These changes were mainly compensated by inverse variations in the proportions of saturated and oleic acids. In contrast to the triglycerides there appears to be no significant seasonal differences in the fatty acid patterns of the phospholipids.