| Summary: | As in mammals, a critical functional role for n-3HUFA (highly unsaturated fatty acids), specifically docosahexaenoic acid (DHA; 22:6n-3), in neural tissues has been established in larval and juvenile fish. Accumulation of DHA in brain during development has been demonstrated in several marine fish species. A very low rate of DHA biosynthesis was observed in turbot brain but a rapid accumulation of DHA in brain of turbot and gilthead sea bream was observed during weaning from live to pelleted food. The incorporation of [1- 14C] linolenic acid (LNA; 18:3n-3) and [1- 14C] DHA in juvenile turbot brain cells showed no significant differences between the amounts of LNA and DHA incorporated into brain phospholipids demonstrating no preferential uptake and incorporation of DHA into brain cells. However, during 24h incubation, 1.1 % and 8.5 % of radioactivity from [1- 14C] LNA and [1- 14C] eicosapentaenoic acid (EPA; 20:5n-3), respectively, were recovered in the DHA fraction of turbot brain lipids. Thus, LNA bioconversion cannot contribute significantly to brain DHA, whereas EPA can to a greater extent. In a further study, the in vivo metabolism of intraperitoneally injected [1- 14C] LNA in liver, brain and eyes of juvenile rainbow trout and gilthead sea bream showed that, although the sea bream incorporated more LNA into its lipids, the bioconversion
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