Fatty acid synthase is a multifunctional enzyme involved in the formation of fatty acids. Despite the role of fatty acids in cell signalling and energy metabolism, and as precursors to pheromones and hydrocarbons that waterproof the cuticle, the insect fatty acid synthases have been scarcely studied. Here we perform the molecular characterization of three fatty acid synthase genes (fatty acid synthase RPRC000123, RPRC000269 and RPRC002909) in the Chagas disease vector, Rhodnius prolixus. Gene expression screening by reverse transcription quantitative PCR showed that RPRC000123 and RPRC002909 are expressed almost exclusively in the integument tissue whilst RPRC000269 is mostly expressed in the fat body and also in several body organs. Phylogenetic analysis, together with gene expression results, showed that RPRC000269, RPRC002909 and RPRC000123 are orthologues of Drosophila melanogaster fatty acid synthase 1 (FASN1), FASN2 and FASN3 genes, respectively. After RNA interference‐mediated knockdown of RPRC000123, insects died immediately after moulting to the next developmental stage. However, mortality was prevented by placing the insects under saturated humidity conditions, suggesting that dehydration might play a role in the insects’ death. Lipid analyses in RPRC000123‐silenced insects showed reduced amounts of integument fatty acids and methyl‐branched hydrocarbons, compared to controls. These data support an important role for FASN3 in the biosynthesis of the precursors to hydrocarbons that waterproof the insect cuticle.

中文翻译：

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来自Rhodnius prolixus的被膜组织的脂肪酸合酶基因（FASN3）有助于角质层失水调节。

脂肪酸合酶是一种参与脂肪酸形成的多功能酶。尽管脂肪酸在细胞信号传导和能量代谢中起着作用，并且作为信息素和使表皮防水的碳氢化合物的前体，但昆虫脂肪酸合酶的研究很少。在这里，我们在Chagas病载体Rhodnius prolixus中执行了三个脂肪酸合酶基因（脂肪酸合酶RPRC000123，RPRC000269和RPRC002909）的分子表征。通过逆转录定量PCR进行的基因表达筛选显示，RPRC000123和RPRC002909几乎全部在外被膜组织中表达，而RPRC000269主要在脂肪体内和多个身体器官中表达。系统发育分析和基因表达结果表明，RPRC000269，RPRC002909和RPRC000123分别是果蝇 脂肪酸合酶1（FASN1），FASN2和FASN3基因的直系同源物。在RNA干扰介导的RPRC000123敲低后，昆虫蜕皮到下一发育阶段后立即死亡。但是，通过将昆虫置于饱和湿度条件下可以防止死亡，这表明脱水可能在昆虫的死亡中起作用。RPRC000123中的脂质分析与对照组相比，沉默的昆虫显示出被膜中的脂肪酸和甲基支链的碳氢化合物减少。这些数据支持FASN3在使昆虫表皮防水的烃的前体的生物合成中的重要作用。