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Golden pompano Trachinotus ovatus is an important farmed carnivorous marine teleost. Although some enzymes for long‐chain polyunsaturated fatty acid (LC‐PUFA) biosynthesis have been identified, the ability of T. ovatus for endogenous biosynthesis is unknown. Here, we evaluated in vivo LC‐PUFA synthesis in a 56‐day culture experiment using six diets (D1–D6) formulated with linseed and soybean oils to produce dietary linolenic/linoleic acid (ALA/LA) ratios ranging from 0.14 to 2.20. The control diet (D0) used fish oil as lipid source. The results showed that, compared with the corresponding indices of fish fed D0, the weight gain rate and specific growth rate as well as the contents of eicosapentaenoic (EPA) and docosahexaenoic acids in tissues (liver, muscle, brain and eye) of D1–D6 groups were significantly lower (p <.05). These data suggested that T. ovatus could not synthesize LC‐PUFA from C18 PUFA or such ability was very low. However, tissue levels of 20:4n‐3 in fish fed diets D1–D6 were higher than that of D0 fish (p <.05), and positively correlated with dietary ALA/LA ratio, while levels of EPA showed no difference among the D1–D6 groups. These results indicated that Δ5 desaturation, required for the conversion of 20:4n‐3 to EPA, may be lacking or very low, suggesting incomplete LC‐PUFA biosynthesis ability in T. ovatus. [ABSTRACT FROM AUTHOR]

Elongase of very long-chain fatty acids (Elovl) 4 probably plays a crucial role in marine fish species, where lack of Elovl2 has been considered as one possible reason for their low long-chain polyunsaturated fatty acids' (LC-PUFAs) biosynthetic capability. Elongase of very long-chain fatty acids 4 is the most recent member of the Elovl family that has been investigated in fish. Here, we report the molecular cloning and functional characterization of putative elovl4 cDNA isolated from marine teleost, Epinephelus coioides, and its expression in response to dietary n-3 LC-PUFA and docosahexaenoic acid (DHA) to eicosapentaenoic acid (EPA) ratio. The elovl4 cDNA of grouper was 2341 bp including 301 bp of 5′-untranslated region (UTR), 918 bp of the coding region that encodes 305 amino acids (AA) and 1122 bp of 3′UTR. Heterologous expression in yeast demonstrated that grouper Elovl4 could elongate saturated fatty acids (FA), especially 24:0 and 26:0, up to 36:0. Also, grouper Elovl4 effectively converted C20 and C22 polyunsaturated FAs to elongated polyenoic products up to C36. Tissue distribution analysis revealed that Elovl4 were widely transcribed in various tissues with the highest level in eye, brain and testis as described in other teleosts. The transcript level of elovl4 was significantly affected by dietary n-3 LC-PUFA and high LC-PUFA level repressess its expression. However, the ratio of DHA to EPA had no significant influence on its expression. These results may contribute to better understanding the LC-PUFA biosynthetic pathway in this fish species. [ABSTRACT FROM AUTHOR]

The effects of formulated feeds on Paracentrotus lividus broodstock performances and carotenoid compositions were investigated. Performance of offspring derived from each dietary treatment was compared to determine whether maternal provisioning of nutrients affected offspring development and survival under commercial culture conditions. At the end of the experimental period (3 months), urchins were induced to spawn, relative fecundity measured, and offspring derived from each treatment were reared independently and survival up to competence assessed. Carotenoid composition of the gonads was also measured. Data showed that the highest dietary protein content significantly improved somatic growth, whereas higher lipid content increased gonadal index ( GI) consistent with the use of gonads as nutrient storage in sea urchins. Nonetheless, gonad lipid concentration was not significantly different between treatments indicating that higher dietary lipid content favoured gonadal size rather than increase lipid content of the gonadal tissue. Interestingly, GI and fecundity were not correlated, although the latter may have been enhanced by dietary xanthophyll. This suggests the importance of including carotenoids in broodstock diets to enhance hatchery outputs. This study also indicated that, although broodstock diet can influence fecundity, it had no significant impact on larval survival, which could instead be influenced by rearing conditions. [ABSTRACT FROM AUTHOR]