Influence of Parental Fatty Acid Desaturase 2 () Expression and Diet on Gilthead Seabream () Offspring Expression during Ontogenesis.

Previous studies have shown that it is possible to increase the ability of marine fish to produce long-chain polyunsaturated fatty acid from their 18C precursors by nutritional programming or using broodstock with a higher fatty acyl desaturase 2 () expression. However, those studies failed to show the effect of these interventions on the expression of the gene in the developing egg. Moreover, there were no studies on the temporal expression of the during ontogeny in the gilthead sea bream (). In order to determine the changes in expression of during ontogeny, gilthead sea bream broodstock with a high (HRO) or low (LRO) expression fed a diet previously used for nutritional programming, or a fish oil-based diet (LFO) were allowed to spawn. The samples were taken at the stages of spawning, morula, high blastula, gastrula, neurula, heart beating, hatch and 3 day-old first exogenous feeding larvae to determine expression throughout embryonic development. The results showed the presence of mRNA in the just spawned egg, denoting the maternal mRNA transfer to the developing oocyte. Later, expression increased after the neurula, from heart beating until 3-day-old larvae, denoting the transition from maternal to embryonic gene expression. In addition, the eggs obtained from broodstock with high expression showed a high docosahexaenoic acid content, which correlated with the downregulation of the expression found in the developing embryo and larvae. Finally, feeding with the nutritional programming diet with the partial replacement of fish oil by rapeseed oil did not affect the long chain polyunsaturated fatty acid (LC-PUFA) contents nor expression in the gilthead sea bream developing eggs.