Fatty acid analyses of phosphoglycerides from tissues of the clam Chlamys islandica (Muller) and the starfish Ctenodiscus crispatus (Retzius) from Balsfjorden,Northern Norway

Fatty acid analyses of phosphoglycerides from Chlamys islandica (Muller) and Ctenodiscus crispants (Retzius) show several interesting features. Major phospholipids from the ovaries and muscles of Chlamys have high levels of (n-3) polyunsaturated fatty acids (PUFA). The phosphatidylinositol (PtdIns) from these tissues contains, however, large amounts of arachidonic acid, 20:4(n?6), so that the $\text{(n?3)}\text{(n?6)}$ ratio of PtdIns is considerably lower than that of the other phospholipids. In contrast, the major phospholipids from the ovaries of Ctenodiscus contain approximately equal amounts of (n?6), mostly 20:4(n?6), and (n?3)PUFA. The 20:4(n?6) is mostly in phosphatidylethanolamine (PtdEtn) and PtdIns and the $\text{(n?3)}\text{(n?6)}$ ratio is again lowest in PtdIns. The PtdIns in both species is also rich in 18:0 and consequently resembles PtdIns from elasmobranchs, marine teleosts, and terrestrial mammals. The results are discussed in relation to dietary origins of PUFA in benthic marine animals and to metabolic functions of PtdIns.