Key Laboratory of Experimental Marine Biology, Institute of Oceanology, Chinese Academy of Sciences, 7 Nanhai Road, Qingdao 266071, China.
Gen Comp Endocrinol. 2012 Jun 1;177(2):246-55. doi: 10.1016/j.ygcen.2012.04.010. Epub 2012 Apr 26.
More and more evidence indicates that the insulin-like androgenic gland hormone (IAG) plays an important role in male sexual differentiation in crustaceans. In the present study, two IAG isoforms (Fc-IAG1 and Fc-IAG2) were identified from the penaeid shrimp Fenneropenaeus chinensis. Sequence analysis of IAG gene (Fc-IAG) showed that Fc-IAG1 and Fc-IAG2 were generated by alternative splicing of Fc-IAG pre-mRNA, and they shared almost the same deduced amino acid sequence. Both of them were composed of signal peptide, B chain, C peptide and A chain. They both contained the six conserved cysteine residues and a putative N-linked glycosylated site like IAGs reported in other crustacean species. Tissue distribution and in situ hybridization analysis revealed that they had the highest expression level in the androgenic gland. The transcripts of Fc-IAG1 and Fc-IAG2 could also be detected in hepatopancreas and nerve cord of both sexes at a low expression level. Analysis on their temporal expression profiles showed that they expressed at all embryonic and post-larvae stages. The expression of Fc-IAG1 at different developmental stages displayed a low and stable manner, while the expression of Fc-IAG2 began to increase from post-larvae stages, which suggested that Fc-IAG2 might be involved in male sexual differentiation. In the 5' flanking sequence of Fc-IAG, putative binding sites for transcription factors regulating transcription of hormone genes and genes related to sexual development were predicted, which provided us a primary understanding on the regulation mechanism of Fc-IAG gene. This is the first time to report the gene structure of IAG gene and distinct variants of IAG transcripts in crustaceans.
越来越多的证据表明，胰岛素样雄激素腺激素（IAG）在甲壳动物的雄性性分化中发挥着重要作用。本研究从对虾（Fenneropenaeus chinensis）中鉴定出两种 IAG 同工型（Fc-IAG1 和 Fc-IAG2）。IAG 基因（Fc-IAG）的序列分析表明，Fc-IAG1 和 Fc-IAG2 是由 Fc-IAG 前体 mRNA 的选择性剪接产生的，它们共享几乎相同的推断氨基酸序列。它们都由信号肽、B 链、C 肽和 A 链组成。它们都含有六个保守的半胱氨酸残基和一个假定的 N-连接糖基化位点，类似于其他甲壳动物中报道的 IAGs。组织分布和原位杂交分析表明，它们在精巢中表达水平最高。在两性的肝胰腺和神经索中也可以检测到 Fc-IAG1 和 Fc-IAG2 的转录本，但表达水平较低。对它们的时间表达谱进行分析表明，它们在所有胚胎和幼体阶段都有表达。Fc-IAG1 在不同发育阶段的表达呈低而稳定的方式，而 Fc-IAG2 的表达从幼体阶段开始增加，这表明 Fc-IAG2 可能参与雄性性分化。在 Fc-IAG 的 5' 侧翼序列中，预测了调节激素基因和与性发育相关基因转录的转录因子的潜在结合位点，这为我们提供了对 Fc-IAG 基因调控机制的初步理解。这是首次报道甲壳动物 IAG 基因的基因结构和 IAG 转录本的不同变体。
