THE INCORPORATION AND METABOLISM OF POLYUNSATURATED FATTY-ACIDS IN PHOSPHOLIPIDS OF CULTURED-CELLS FROM CHUM SALMON (ONCORHYNCHUS-KETA)

The incorporation and metabolism of (n - 3) and (n - 6) polyunsaturated fatty acids were studied in a cell line derived from chum salmon heart (CHH-1). Supplementing media with 25 muM fatty acid considerably altered the cellular fatty acid composition but did not affect the lipid class composition or cause the appearance of cytoplasmic lipid droplets. CHH-1 cells exhibited considerable DELTA-6-desaturase activity but showed no preference between (n - 3) and (n - 6)PUFA substrates. CHH-1 cells also possess DELTA-5-desaturase activity which showed preference towards (n - 3)PUFA, but DELTA-4-desaturase activity was totally absent. Elongation of 20-carbon PUFA was especially active in CHH-1 cells with 22-carbon PUFA being specifically incorporated into PE and PS lipid classes. The fatty acid composition of PI indicated specific incorporation of 20-carbon PUFA into this lipid class. Supplementation with 22:6(n - 3) generated fatty acid compositions more closely resembling those of intact salmonid hearts. Substantial chain shortening of 22:6(n - 3) to 20:5(n - 3) occurred.