Changes in the fatty acid composition of phospholipids from turbot (Scophthalmus maximus) in relation to dietary polyunsaturated fatty acid deficiencies.

Young turbot (1-20 g) were maintained for not less than 14 weeks on three diets: (1) a control diet containing normal amounts of polyunsaturated fatty acids (PUFA); (2) a diet totally deficient in PUFA; (3) a diet deficient in the (n-6) series of PUFA but containing (n-3) PUFA. At 14 weeks the fatty acid compositions of the phospholipids from liver, gut, gills and muscle were analysed. Large changes in the amounts of PUFA in the phospholipids were found. Fish maintained on the totally PUFA deficient diet 2 had retained arachidonic acid, 20:4(n-6), and docosahexaenoic acid, 22:6(n-3), at the expense of eicosapentaenoic acid, 20:5(n-3). Fish maintained on the (n-6) PUFA-deficient diet (3) contained decreased amounts of 20:4(n-6) and 22:6(n-3) while retaining 20:5(n-3). In all cases phosphatidylinositol had the lowest n-3/n-6 ratios. These results are discussed in terms of PUFA function.