Omega-3 (n-3) long-chain polyunsaturated fatty acids (LC-PUFA, C_20-24), including eicosapentaenoic acid (EPA, 20:5n-3) and docosahexaenoic acid (DHA, 22:6n-3), are involved in numerous biological processes and have a range of health benefits. Fish have long been considered as the main source of n-3 LC-PUFA in human diets. However, the capacity for endogenous biosynthesis of LC-PUFA from C₁₈ PUFA varies in fish species based on the presence, expression and activity of key enzymes including fatty acyl desaturases (Fads) and elongation of very long-chain fatty acids (Elovl) proteins. In this article, we review progress on the identified Fads and Elovl, as well as the regulatory mechanisms of LC-PUFA biosynthesis both at transcriptional and post-transcriptional levels in teleosts. The most comprehensive advances have been obtained in rabbitfish Siganus canaliculatus, a marine teleost demonstrated to have the entire pathway for LC-PUFA biosynthesis, including the roles of transcription factors hepatocyte nuclear factor 4α (Hnf4α), liver X receptor alpha (Lxrα), sterol regulatory element-binding protein 1 (Srebp-1), peroxisome proliferator-activated receptor gamma (Pparγ) and stimulatory protein 1 (Sp1), as well as post-transcriptional regulation by individual microRNA (miRNA) or clusters. This research has, for the first time, demonstrated the involvement of Hnf4α, Pparγ and miRNA in the regulation of LC-PUFA biosynthesis in vertebrates. The present review provides readers with a relatively comprehensive overview of the progress made into understanding LC-PUFA biosynthetic systems in teleosts, and some insights into improving endogenous LC-PUFA biosynthesis capacity aimed at reducing the dependence of aquafeeds on fish oil while maintaining or increasing flesh LC-PUFA content and the nutritional quality of farmed fish.

Omega-3 (n-3) 长链多不饱和脂肪酸 (LC-PUFA, C _20-24 )，包括二十碳五烯酸 (EPA, 20:5n-3) 和二十二碳六烯酸 (DHA, 22:6n-3)，参与许多生物过程并具有一系列健康益处。长期以来，鱼类一直被认为是人类饮食中 n-3 LC-PUFA 的主要来源。然而，从 C _{18内源性生物合成 LC-PUFA 的能力}根据包括脂肪酰基去饱和酶 (Fads) 和超长链脂肪酸 (Elovl) 蛋白的延长在内的关键酶的存在、表达和活性，PUFA 在鱼类中有所不同。在本文中，我们回顾了已鉴定的 Fads 和 Elovl 的进展，以及在硬骨鱼转录和转录后水平上 LC-PUFA 生物合成的调控机制。兔鱼Siganus canaliculatus取得了最全面的进展，一种海洋硬骨鱼被证明具有 LC-PUFA 生物合成的整个途径，包括转录因子肝细胞核因子 4α (Hnf4α)、肝 X 受体 α (Lxrα)、甾醇调节元件结合蛋白 1 (Srebp-1) 的作用、过氧化物酶体增殖物激活受体 γ (Pparγ) 和刺激蛋白 1 (Sp1)，以及单个 microRNA (miRNA) 或簇的转录后调控。该研究首次证明了 Hnf4α、Pparγ 和 miRNA 参与了脊椎动物 LC-PUFA 生物合成的调控。本综述为读者提供了关于理解硬骨鱼中 LC-PUFA 生物合成系统的进展的相对全面的概述，