Long-chain polyunsaturated fatty acid biosynthesis, a process to convert C18 polyunsaturated fatty acids to eicosapentaenoic acid (EPA), docosahexaenoic acid (DHA) or arachidonic acid (ARA) requires the concerted activities of two enzymes, the fatty acyl desaturase (Fads) and elongase (Elovl). This study highlights the cloning, functional characterisation and tissue expression pattern of a Fads and an Elovl from the Boddart's goggle-eyed goby (Boleophthalmus boddarti), a mudskipper species widely distributed in the Indo-Pacific region. Phylogenetic analysis revealed that the cloned Fads and Elovl are clustered with other teleost Fads2 and Elovl5 orthologs, respectively. Interrogation of the genome of several mudskipper species, namely B. pectinirostris, Periophthalmus schlosseri and P. magnuspinnatus revealed a single Fads2 for each respective species while two elongases, Elovl5 and Elovl4 were detected. Using a heterologous yeast assay, the B. boddarti Fads2 was shown to possess low desaturation activity on C18 PUFA. In addition, there was no desaturation of C20 and C22 substrates. In comparison, the Elovl5 showed a wide range of substrate specificity, with capacity to elongate C18, C20 and C22 PUFA substrates. We identified an amino acid residue in the B. boddarti Elovl5 that affect the capacity to elongate C22:5n-3. Both genes are highly expressed in brain tissue. Among all tissues, DHA is highly concentrated in neuron-rich tissues while EPA is highly deposited in gills. Taken together, the results showed that due to disability of desaturation steps, B. boddarti is unable to biosynthesis LC-PUFA, relying on dietary intake to acquire these nutrients. This article is protected by copyright. All rights reserved.

中文翻译：

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Boddart 眼镜虎鱼中脂肪酰基去饱和酶 Fads2 和 Elovl5 延长酶的功能表征，Boleophthalmus boddarti（Gobiidae）表明长链多不饱和脂肪酸生物合成无能力

长链多不饱和脂肪酸生物合成，将 C18 多不饱和脂肪酸转化为二十碳五烯酸 (EPA)、二十二碳六烯酸 (DHA) 或花生四烯酸 (ARA) 的过程需要两种酶的协同活动，即脂肪酰基去饱和酶 (Fads) 和延长酶（Elovl）。这项研究重点介绍了来自 Boddart 眼镜虎鱼 (Boleophthalmus boddarti) 的 Fads 和 Elovl 的克隆、功能表征和组织表达模式，这是一种广泛分布于印度-太平洋地区的弹涂鱼。系统发育分析表明，克隆的 Fads 和 Elovl 分别与其他硬骨鱼 Fads2 和 Elovl5 直系同源物聚类。询问几种弹涂鱼的基因组，即 B. pectinirostris、Periophthalmus schlosseri 和 P. magnuspinnatus 显示每个物种的单个 Fads2，同时检测到两个延伸酶 Elovl5 和 Elovl4。使用异源酵母测定，B. boddarti Fads2 显示对 C18 PUFA 具有低去饱和活性。此外，C20 和 C22 底物没有去饱和。相比之下，Elovl5 显示出广泛的底物特异性，能够延长 C18、C20 和 C22 PUFA 底物。我们在 B. boddarti Elovl5 中鉴定了影响延长 C22:5n-3 能力的氨基酸残基。这两个基因在脑组织中都高度表达。在所有组织中，DHA 高度集中在富含神经元的组织中，而 EPA 高度沉积在鳃中。综上所述，结果表明，由于去饱和步骤失效，B. boddarti 无法生物合成 LC-PUFA，依靠饮食摄入来获取这些营养素。本文受版权保护。版权所有。