School of Energy and Environment and State Key Laboratory of Marine Pollution, City University of Hong Kong, Kowloon, Hong Kong, China.
Research Centre for the Oceans and Human Health, City University of Hong Kong Shenzhen Research Institute, Shenzhen, 518057, China.
Sci Rep. 2023 Jan 19;13(1):1080. doi: 10.1038/s41598-023-28342-4.
Long-chain polyunsaturated fatty acids (LC-PUFA), including eicosapentaenoic acid and docosahexaenoic acid, are the essential fatty acids for organs to maintain various biological functions and processes. The threadfin fish Eleutheronema, with its rich nutritional value especially the high fatty acid contents, has become one of the promising aquaculture species in China and the potential food source of fatty acids for human consumption. However, the molecular basis underlying the biosynthesis of fatty acids in Eleutheronema species is still unknown. The elongation of the very long-chain fatty acids (Elovl) gene family in fish plays several critical roles in LC-PUFA synthesis. Therefore, in the present study, we performed genome-wide identification of the Elovl gene family to study their evolutionary relationships and expression profiles in two threadfin fish species Eleutheronema tetradactylum and Eleutheronema rhadinum, the first representatives from the family Eleutheronema. Phylogenetic analysis revealed that the Elovl genes in Eleutheronema were classified into six subfamilies (elovl1a/1b, elovl4a/4b, elovl5, elovl6/6 l, elovl7a, elovl8b). Phylogenetic, gene structure, motif, and conserved domain analysis indicated that the Elovl genes were highly conserved within the same subfamily in Eleutheronema. In addition, the Elovl genes were distributed in 7/26 chromosomes, while the duplicated gene pair, elovl4a and elovl4b, showed collinear relationships. The predicted secondary structure patterns and the 3D models revealed the highly similar functions and evolutionary conserved structure of Elovl proteins in Eleutheronema. The selection pressure analysis revealed that Elovl genes underwent strong purifying selection during evolution, suggesting that their functions might be evolutionarily conserved in Eleutheronema. Additionally, the expression patterns of Elovl genes in different tissues and species were distinct, indicating the possible functional divergence during evolution in the Eleutheronema genus. Collectively, we provided the first comprehensive genomic information on Elovl genes in threadfin fish Eleutheronema. This study enhanced the understanding of the underlying mechanisms of fatty acids biosynthesis in Eleutheronema, and provided new insights on breeding new varieties of fatty acids-enriched fish with potential benefits to farmers and the health of consumers.
长链多不饱和脂肪酸（LC-PUFA），包括二十碳五烯酸和二十二碳六烯酸，是器官维持各种生物功能和过程所必需的脂肪酸。金线鱼属鱼类因其丰富的营养价值，特别是高脂肪酸含量，已成为中国有前途的养殖品种之一，也是人类消费脂肪酸的潜在食物来源。然而，金线鱼属鱼类脂肪酸生物合成的分子基础尚不清楚。鱼类中非常长链脂肪酸延长酶（Elovl）基因家族的延伸在 LC-PUFA 合成中起着几个关键作用。因此，在本研究中，我们对两个金线鱼属物种 Eleutheronema tetradactylum 和 Eleutheronema rhadinum 的 Elovl 基因家族进行了全基因组鉴定，这是该属的第一个代表，以研究它们的进化关系和表达谱。系统发育分析表明，金线鱼属的 Elovl 基因分为六个亚家族（elovl1a/1b、elovl4a/4b、elovl5、elovl6/6l、elovl7a、elovl8b）。系统发育、基因结构、基序和保守结构域分析表明，Elovl 基因在金线鱼属的同一亚家族内高度保守。此外，Elovl 基因分布在 7/26 条染色体上，而重复基因对 elovl4a 和 elovl4b 则表现出共线性关系。预测的二级结构模式和 3D 模型揭示了 Eleutheronema 中 Elovl 蛋白的高度相似功能和进化保守结构。选择压力分析表明，Elovl 基因在进化过程中经历了强烈的纯化选择，表明它们的功能在 Eleutheronema 中可能是进化保守的。此外，Elovl 基因在不同组织和物种中的表达模式不同，表明在 Eleutheronema 属的进化过程中可能存在功能分化。总的来说，我们提供了金线鱼属鱼类 Elovl 基因的第一份全面基因组信息。这项研究增强了对 Eleutheronema 脂肪酸生物合成潜在机制的理解，并为培育具有潜在益处的富含脂肪酸的新型鱼类提供了新的见解，对农民和消费者的健康都有益处。
