Phospholipid fatty acid composition and cold tolerance in two species of barnacle, Balanus balanoides (L.) and Elminius modestus Darwin. 1. Summer versus winter variations in phospholipid fatty acid composition of whole animals
Tooke, NE.; Holland, DL.
Journal of Experimental Marine Biology and Ecology 873: 241-253
Total phospholipids, choline phosphoglycerides, ethanolamine phosphoglycerides, phosphatidylserine + phosphatidylinositol, and sphingomyelin were isolated in winter and summer from whole bodies of the intertidal barnacles, B. balanoides (L.) and E. modestus Darwin. The fatty acid compositions were determined for these fractions for 2 yr. Parallel determinations of cold tolerance indicated that the tolerance of B. balanoides to low temperatures increased from summer to winter while that of E. modestus remained unchanged. Fractions from both species showed seasonal changes in fatty acid composition but those which were consistent between years and which differed between species were confined to sphingomyelin. In E. modestus these changes involved a winter to summer increase in monounsaturated fatty acid levels met by a decrease in the level of saturated fatty acids. The trend for B. balanoides was similar but less marked. Sphingomyelin was also characteristic in having a low level of polyunsaturated fatty acids, in contrast with other phospholipid fractions examined. Seasonal changes in the fatty acid composition of sphingomyelin, a phospholipid which is located primarily in the plasma membrane, may play some as yet undetermined role in the avoidance of freezing injury resulting from damage to this membrane.