Long-chain (≥C₂₀) polyunsaturated fatty acids (LC-PUFA), including eicosapentaenoic acid (EPA, 20:5n-3), arachidonic acid (ARA, 20:4n-6) and docosahexaenoic acid (DHA, 22:6n-3), are essential in multiple physiological processes, especially during early development of vertebrates. LC-PUFA biosynthesis is achieved by two key families of enzymes, fatty acyl desaturases (Fads) and elongation of very long-chain fatty acid (Elovl). The present study determined the expression patterns of genes encoding desaturases (fads1 and fads2) and elongases (elovl2 and elovl5) involved in the LC-PUFA biosynthesis during early life-stages of the tropical gar Atractosteus tropicus. We further analyzed the fatty acid profiles during early development of A. tropicus to evaluate the impact of Fads and Elovl enzymatic activities. Specific oligonucleotides were designed from A. tropicus transcriptome to perform qPCR (quantitative polymerase chain reaction) on embryonic and larval stages, along with several organs (intestine, white muscle, brain, liver, heart, mesenteric adipose, kidney, gill, swim bladder, stomach, and spleen) collected from juvenile specimens. Fatty acid content of feeds and embryonic and larval stages were analyzed. Results show that fads1, fads2, elovl2 and elovl5 expression was detected from embryonic stages with expression peaks from day 15 post hatching, which could be related to transcriptional and dietary factors. Moreover, fads1, fads2 and elovl2 showed a higher expression in intestine, while elovl5 showed a higher expression in liver, suggesting that the tropical gar activates its LC-PUFA biosynthetic machinery to produce ARA, EPA and DHA to satisfy physiological demands at crucial developmental milestones during early development.

长链 (≥C ₂₀ ) 多不饱和脂肪酸 (LC-PUFA)，包括二十碳五烯酸 (EPA, 20:5n-3)、花生四烯酸 (ARA, 20:4n-6) 和二十二碳六烯酸 (DHA, 22:6n) -3)，在多种生理过程中是必不可少的，尤其是在脊椎动物的早期发育过程中。LC-PUFA 的生物合成是通过两个关键的酶家族实现的，即脂肪酰基去饱和酶 (Fads) 和超长链脂肪酸延伸 (Elovl)。本研究确定了编码去饱和酶基因（的表达模式FADS1和FADS2）和延伸酶（ELOVL2和ELOVL5在热带GAR的早期生命阶段中涉及的LC-PUFA的生物合成）Atractosteus tropicus. 我们进一步分析了A. tropicus早期发育过程中的脂肪酸谱，以评估 Fads 和 Elovl 酶活性的影响。特定的寡核苷酸是从A. tropicus转录组设计的，用于在胚胎和幼虫阶段以及多个器官（肠道、白肌、大脑、肝脏、心脏、肠系膜脂肪、肾脏、鳃、鳔、胃和脾）从幼年标本中收集。分析了饲料和胚胎和幼虫阶段的脂肪酸含量。结果显示fads1 , fads2 , elovl2和elovl5从胚胎阶段检测到表达，孵化后第 15 天出现表达峰值，这可能与转录和饮食因素有关。此外，潮流1，潮流2和ELOVL 2显示在肠中高表达，而ELOVL 5显示出肝脏中高表达，这表明热带GAR激活其LC-PUFA生物合成机构，以产生ARA，EPA和DHA，以满足生理需求在早期发展的关键发展里程碑。