Abstract
Simple SummaryThe present study was on the gene expression of a rate-limiting enzyme in long chain polyunsaturated fatty acids (LC-PUFAs), fatty acyl desaturase 2 (fads2), throughout the embryonic development of a gilthead sea bream. The results showed a maternal transfer of fads2 mRNA to the developing oocyte. The embryonic fads2 expression might start after the neurula stage. No effect was found in fads2 expression in developing eggs from broodstock fed with a diet rich in rapeseed oil or fish oil. The present study provides information on the change of LC-PUFA biosynthesis during embryogenesis.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 (fads2) expression. However, those studies failed to show the effect of these interventions on the expression of the fads2 gene in the developing egg. Moreover, there were no studies on the temporal expression of the fads2 during ontogeny in the gilthead sea bream (Sparus aurata). In order to determine the changes in expression of fads2 during ontogeny, gilthead sea bream broodstock with a high (HRO) or low (LRO) fads2 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 fads2 expression throughout embryonic development. The results showed the presence of fads2 mRNA in the just spawned egg, denoting the maternal mRNA transfer to the developing oocyte. Later, fads2 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 fads2 expression showed a high docosahexaenoic acid content, which correlated with the downregulation of the fads2 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 fads2 expression in the gilthead sea bream developing eggs.
Highlights
Long chain polyunsaturated fatty acids (LC-PUFAs), docosahexaenoic acid (22:6n-3, DHA), eicosapentaenoic acid (20:5n-3, EPA) and arachidonic acid (20:4n-6, ARA), play relevant structural and functional roles in animal cells [1,2]
To obtain broodstock with a different ability to synthesize long chain polyunsaturated fatty acid (LC-PUFA) from the precursors linoleic acid (18:2n-6) and α-linolenic acid (18:3n-3), 3 months prior the spawning season, 185 gilthead sea bream brood fish of 1–2 kg were fed for one month at a diet high in linoleic acid and α-linolenic acid and low in LC-PUFAs promoting the upregulation of fads2 [22]
Analysis of the average fads2 expression values in eggs and larvae for all experimental groups showed an increase during embryogenesis, following a significant lineal regression (R2 = 0.95, p < 0.001)
Summary
Long chain polyunsaturated fatty acids (LC-PUFAs), docosahexaenoic acid (22:6n-3, DHA), eicosapentaenoic acid (20:5n-3, EPA) and arachidonic acid (20:4n-6, ARA), play relevant structural and functional roles in animal cells [1,2]. They are critical components of cell and organelle membranes [3] and their derived molecules, such as eicosanoids or docosanoids, participate in cell signaling processes [4]. Is the traditional source of LC-PUFAs. FO is mostly derived from capture fisheries, which is a limited resource that would restrain the sustainable development of aquaculture. Despite vegetable oils lacking LC-PUFAs, they are abundant in their
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