Low C18 to C20 fatty acid elongase activity and limited conversion of stearidonic acid, 18:4(n-3), to eicosapentaenoic acid, 20:5(n-3), in a cell line from the turbot, Scophthalmus maximus

Citation

Ghioni C, Tocher DR, Bell M, Dick JR & Sargent JR (1999) Low C18 to C20 fatty acid elongase activity and limited conversion of stearidonic acid, 18:4(n-3), to eicosapentaenoic acid, 20:5(n-3), in a cell line from the turbot, Scophthalmus maximus. Biochimica et Biophysica Acta Molecular and Cell Biology of Lipids, 1437 (2), pp. 170-181. https://doi.org/10.1016/S1388-1981%2899%2900010-4

Abstract
The TF cell line, derived from a top predatory, carnivorous marine teleost, the turbot (Scophthalmus maximus), is known to have a limited conversion of C18 to C20 polyunsaturated fatty acids (PUFA). To illuminate the underlying processes, we studied the conversions of stearidonic acid, 18:4(n-3), and its elongation product, 20:4(n-3), in TF cells and also in a cell line, AS, derived from Atlantic salmon (Salmo salar), by adding unlabelled (25 uM), U-14C (1 uM) or deuterated (d5; 25 uM) fatty acids. Stearidonic acid, 18:4(n-3), was metabolised to 20:5(n-3) in both cells lines, but more so in AS than in TF cells. Delta-5 desaturation was more active in TF cells than in AS cells, whereas C18 to C20 elongation was much reduced in TF as compared to AS cells. Only small amounts of docosahexaenoic acid (22:6(n-3)) were produced by both cell lines, although there was significant production of 22:5(n-3) in both cultures, especially when 20:4(n-3) was supplemented. We conclude that limited elongation of C18 to C20 fatty acids rather than limited fatty acyl Delta-5 desaturation accounts for the limited rate of conversion of 18:3(n-3) to 20:5(n-3) in the turbot cell line, as compared to the Atlantic salmon cell line. The results can account for the known differences in conversions of C18 to C20 PUFA by the turbot and the Atlantic salmon in vivo.

Keywords
Fish; Cell culture; Fatty acids; Polyunsaturated fatty acid; biosynthesis; Desaturation; Elongation; Metabolism; AS cell line; TF cell line; Atlantic salmon; Turbot; Lipoproteins Fish; Fishes Feeding and feeds; Atlantic salmon

Journal
Biochimica et Biophysica Acta Molecular and Cell Biology of Lipids: Volume 1437, Issue 2

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Mr James Dick

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