EFFECT OF TEMPERATURE ON THE INCORPORATION INTO PHOSPHOLIPID CLASSES AND METABOLISM VIA DESATURATION AND ELONGATION OF N-3 AND N-6 POLYUNSATURATED FATTY-ACIDS IN FISH CELLS IN CULTURE

The incorporation of 18:2n-6, 18:3n-3, 20:4n-6 and 20:5n-3 was greater at 10°C than at 22°C in Atlantic salmon (AS), rainbow trout (RTG-2) and turbot (TF) cells. However, there were generally no significant differences between the amount of incorporation of all four polyunsaturated fatty acids (PUFA) into total lipid within a cell type at either 22°C or 10°C. The distributions of the PUFA between individual phospholipid classes at 22°C was essentially the same in AS and TF cells-with the C18 PUFA the order of incorporation in these cells was phosphatidylcholine (PC) > phosphatidylethanolamine (PE) > phosphatidic acid/cardiolipin (PA/CL); with 20:4n-6 the order was PE and phosphatidylinositol (PI)>PC; with 20:5n-3, PE>PC. In RTG-2 cells at 22°C the distributions of the C18 PUFA were similar to the other cell lines, but with 20:4n-6 the order was PC>PI>PE, and with 20:5n-3 it was PC>PE. At 10°C the incorporation of C18 PUFA into PC increased and into PE and PA/CL decreased, in general, in all cell lines. Incorporation of 20:5n-3 into PC and PE was increased and decreased at 10°C, respectively, in AS and TF cells, whereas in RTG-2 cells the changes at 10°C were opposite i.e., increased in PE and decreased in PC. With 20:4n-6, incorporation into PC at 10°C was increased in all cell lines with decreased incorporation into PI in AS and RTG-2 cells and into PE in AS and TF cells, whereas incorporation of 20:4n-6 into PE increased in RTG-2 cells. The metabolism via desaturation and elongation of the n-3 PUFA was greater than that of the equivalent n-6 PUFA in all cell lines, irrespective of temperature. There was less conversion of the C18 PUFA at 10°C than at 22°C in RTG-2 and TF cells, but the conversion of 18:3n-3 by AS cells was increased at 10°C. Temperature had no effect on the conversion of the C20 PUFA. © 1990 American Oil Chemists' Society (AOCS).