Fisheries College, Guangdong Ocean University, Zhanjiang, Guangdong, PR China.
Fisheries College, Guangdong Ocean University, Zhanjiang, Guangdong, PR China; Nanhai Economic Shrimp Breeding and Culture Laboratory, PR China.
Gene. 2021 May 25;782:145529. doi: 10.1016/j.gene.2021.145529. Epub 2021 Feb 23.
Male sex differentiation in the crustacean is best known to be controlled by the insulin-like androgenic gland hormone (IAG). In this report, the cDNA and gene of the shrimp Fenneropenaeus merguiensis FmIAG were studied and characterized. FmIAG gene shares a high sequence identity in the coding region as well as the promoter region with that of F. chinensis. FmIAG gene is most likely consists of 5 exons and 4 introns. The cDNA reported here is the most abundant transcript that retained cryptic intron 4. The use of different splicing acceptor sites in exon 2 can produce a long-form FmIAG transcript variant with 6 additional amino acids inserted. Splicing of cryptic intron 4 would produce a transcript variant with a different C-terminal end. Therefore 4 different FmIAG transcripts can be produced from the FmIAG gene. During the molt cycle, the expression level of FmIAG was low in the early intermolt, increase steadily towards the late premolt and decreased rapidly in the early postmolt. In addition to the androgenic gland, FmIAG is also expressed in the hepatopancreas and ovary of adult females. Unilateral eyestalk ablation caused a significant increase in FmIAG transcript suggesting that the eyestalk consists of inhibiting factor(s) that suppressesFmIAGexpression. To explore the function of FmIAG in males, injection of FmIAG dsRNA knock-down the expression of FmIAG and up-regulated the expression of the vitellogenin gene in the testis and hepatopancreas. Interestingly a CHH-like gene identified in the androgenic gland was down-regulated. CHH-like gene knock-down resulted in altered expression of FmIAG in males suggesting that the CHH-like may be involved in FmIAG's regulation. RT-PCR with specific primers to the different transcript variant were used to determine if there is an association of different sizes of male and the type of IAG transcript. Results indicated that a high percentage of the large male shrimp expressed the long-form of FmIAG. The results suggested that FmIAG may be useful as a size marker for male shrimp aquaculture. In summary, the results of this study have expanded our knowledge of shrimp insulin-like androgenic gland hormone in male sex development and its potential role as a marker gene for growth regulation in shrimp.
甲壳动物的雄性性别分化主要由胰岛素样雄激素腺激素（IAG）控制。在本报告中，研究并表征了虾类斑节对虾 FmIAG 的 cDNA 和基因。FmIAG 基因在编码区和启动子区与中国对虾的基因具有高度的序列同一性。FmIAG 基因可能由 5 个外显子和 4 个内含子组成。报告的 cDNA 是最丰富的转录本，保留了隐藏的内含子 4。第二外显子中不同的剪接受体位点的使用可以产生一个长形式的 FmIAG 转录变体，插入 6 个额外的氨基酸。隐藏内含子 4 的剪接会产生一个具有不同 C 末端的转录变体。因此，FmIAG 基因可以产生 4 种不同的 FmIAG 转录本。在蜕皮周期中，FmIAG 在早期的间蜕期表达水平较低，在晚期的前蜕期逐渐增加，在早期的后蜕期迅速下降。除了雄激素腺外，FmIAG 还在成年雌虾的肝胰腺和卵巢中表达。单侧眼柄切除导致 FmIAG 转录本显著增加，表明眼柄包含抑制因子（s），抑制 FmIAG 的表达。为了探索 FmIAG 在雄性中的功能，注射 FmIAG dsRNA 可降低睾丸和肝胰腺中 FmIAG 的表达，并上调卵黄原基因的表达。有趣的是，在雄激素腺中鉴定出的一个 CHH 样基因下调。CHH 样基因的敲低导致雄性中 FmIAG 的表达发生改变，表明 CHH 样基因可能参与 FmIAG 的调控。使用不同转录变体的特异性引物进行 RT-PCR 以确定不同大小的雄性和 IAG 转录本类型之间是否存在关联。结果表明，高比例的大型虾表达长形式的 FmIAG。结果表明，FmIAG 可作为虾类养殖中雄性大小的标记基因。总之，本研究结果扩展了我们对虾类胰岛素样雄激素腺激素在雄性性别发育中的作用及其作为虾类生长调控标记基因的潜在作用的认识。
