RT info:eu-repo/semantics/article T1 Dietary LC-PUFA and environmental salinity modulate the fatty acid biosynthesis capacity of the euryhaline teleost thicklip grey mullet (Chelon labrosus) A1 Pérez Pérez, José Antonio A1 Marrero, Manuel A1 Monroig, Óscar A1 Betancor, Mónica ´B. A1 Galindo, Ana A1 Bolaños, Ana A1 Acosta, N. Guadalupe A1 Rodríguez, Covadonga A2 Biología Animal y Edafología y Geología A2 NUTRAHLIPIDS (Fisiología de los Lípidos y sus Derivados en la Alimentación Animal y Humana) K1 LC-PUFA biosynthesis K1 Low salinity K1 Diet K1 Chelon labrosus AB The capacity to biosynthesise long-chain (≥C20) polyunsaturated fatty acids (LC-PUFA) depends upon thecomplement and function of key enzymes commonly known as fatty acyl desaturases and elongases. The presence of a Δ5/Δ6 desaturase enabling the biosynthesis of docosahexaenoic acid (22:6n-3, DHA) through the“Sprecher pathway” has been reported in Chelon labrosus. Research in other teleosts have demonstrated that LCPUFA biosynthesis can be modulated by diet and ambient salinity. The present study aimed to assess the combined effects of partial dietary replacement of fish oil (FO) by vegetable oil (VO) and reduced ambient salinity(35 ppt vs 20 ppt) on the fatty acid composition of muscle, enterocytes and hepatocytes of C. labrosus juveniles.Moreover, the enzymatic activity over radiolabelled [1-14C] 18:3n-3 (α-linolenic acid, ALA) and [1-14C] 20:5n-3(eicosapentaenoic acid, EPA) to biosynthesise n-3 LC-PUFA in hepatocytes and enterocytes, and the generegulation of the C. labrosus fatty acid desaturase-2 (fads2) and elongation of very long chain fatty acids protein 5(elovl5) in liver and intestine was also investigated. Recovery of radiolabelled products including stearidonic acid(18:4n-3, SDA), 20:5n-3, tetracosahexaenoic acid (24:6n-3, THA) and 22:6n-3 in all treatments except FO35-fish,provided compelling evidence that a complete pathway enabling the biosynthesis of EPA and DHA from ALA ispresent and active in C. labrosus. Low salinity conditions upregulated fads2 in hepatocytes and elovl5 in both celltypes, regardless of dietary composition. Interestingly, FO20-fish showed the highest amount of n-3 LC-PUFA inmuscle, while no differences in VO-fish reared at both salinities were found. These results demonstrate acompensatory capacity of C. labrosus to biosynthesise n-3 LC-PUFA under reduced dietary supply, and emphasisethe potential of low salinity conditions to stimulate this pathway in euryhaline fish. YR 2024 FD 2024 LK http://riull.ull.es/xmlui/handle/915/35294 UL http://riull.ull.es/xmlui/handle/915/35294 LA en NO https://doi.org/10.1016/j.cbpb.2023.110865 DS Repositorio institucional de la Universidad de La Laguna RD 09-may-2024