Sesquiterpenoid methyl farnesoate (MF), a crustacean equivalent of insect juvenile hormone (JH III), has essential functions in regulating physiological processes in crustaceans, including reproduction and vitellogenesis. Farnesoic acid O-methyltransferase (FAMeT) is a key rate-limiting enzyme catalyzing the conversion of farnesoic acid (FA) to JH/MF in insects and crustaceans. In this study, a full-length cDNA of EsFAMeT from Eriocheir sinensis was isolated and characterized. The deduced EsFAMeT amino acid sequence indicated there were two conserved Methyltransf-FA domains characteristic of FAMeT family proteins. With use of sequence alignment analysis procedures, there was an indication that FAMeT proteins are highly conserved among crustaceans and FAMeT is more closely related to crustacean FAMeT than to insect FAMeT. Results from quantitative real-time PCR analysis revealed there was ubiquitous EsFAMeT in all tissues examined, with greater abundances of mRNA transcripts in the ovary. The transcription of EsFAMeT indicated there were stage-specific patterns in the hepatopancreas and ovary during ovarian development, with the greatest abundance during ovarian development Stages II and III, respectively. To investigate functions of EsFAMeT in vitellogenin biosynthesis in E. sinensis, RNA interference-mediated gene knockdown was used in vitro and in vivo. Injection of EsFAMeT dsRNA resulted in a marked decrease in EsVg (encoding vitellogenin) transcripts in the ovary and hepatopancreas both in vitro and in vivo. Results from the present study indicated EsFAMeT is involved in vitellogenin biosynthesis in the ovary and hepatopancreas of E. sinensis, providing a new resource to study modulatory effects of the FAMeT family of enzymes in crustacean reproduction.

倍半萜类甲基法尼酸 (MF) 是甲壳类动物的昆虫保幼激素 (JH III) 等效物，在调节甲壳类动物的生理过程中具有重要作用，包括繁殖和卵黄生成。Farnesoic acid O-methyltransferase (FAMeT) 是一种关键的限速酶，可催化昆虫和甲壳类动物将 Farnesoic acid (FA) 转化为 JH/MF。在本研究中，来自中华绒螯蟹的EsFAMeT的全长 cDNA被分离和表征。推导的 EsFAMeT 氨基酸序列表明存在 FAMeT 家族蛋白特征的两个保守的 Methyltransf-FA 结构域。通过使用序列比对分析程序，有迹象表明 FAMeT 蛋白在甲壳类动物中高度保守，并且 FAMeT 与甲壳类动物 FAMeT 的关系比与昆虫 FAMeT 的关系更密切。定量实时 PCR 分析结果显示，在所有检查的组织中普遍存在EsFAMeT，卵巢中 mRNA 转录物的丰度更高。EsFAMeT的转录表明在卵巢发育过程中肝胰腺和卵巢存在阶段特异性模式，卵巢发育阶段 II 和 III 的丰度最大。为了研究EsFAMeT在E. sinensis卵黄蛋白生物合成中的功能，在体外和体内使用了 RNA 干扰介导的基因敲低。EsFAMeT dsRNA 的注射导致体外和体内卵巢和肝胰腺中EsVg （编码卵黄蛋白）转录物的显着减少。本研究的结果表明EsFAMeT参与E. sinensis卵巢和肝胰腺中的卵黄原蛋白生物合成，为研究 FAMeT 酶家族在甲壳类动物繁殖中的调节作用提供了新的资源。