Incorporation and metabolism of ( n-3) and ( n-6) polyunsaturated fatty acids in phospholipid classes in cultured Atlantic salmon ( Salmo salar) cells

Abstract

1. 1. The distribution, and the occurrence and relative extent of further desaturation and elongation of various ( n-3) and ( n-6) polyunsaturated fatty acids supplemented to the culture medium was determined in individual phospholipid classes in the Atlantic salmon cell line, AS. 2. 2. AS cells exhibited significant Δ6 and Δ5 desaturase activities whereas Δ4 desaturase activity was very low. 3. 3. The compositional data indicated that individual intermediates and products of the desaturation pathways were associated with specific phospholipid classes probably via mechanisms depending upon the specificities of the acylating enzymes. 4. 4. The percentages of supplemented 18:2( n-6) and 18:3( n-3) were greatest in the phosphatidic acid/cardiolipin fraction (PA/CL), suggesting a role for possibly PA in the initial incorporation of these precursor acids into the phospholipid pool. 5. 5.The 20:4( n-6) composition of phosphatidylinositol (PI) and the tightly controlled mechanisms for maintaining it are consistent with a role for this phospholipid in providing precursor fatty acid for eicosanoid synthesis in fish cells.