Transformer‐2 (Tra‐2) is an mRNA splicing factor that acts in concert with Tra to regulate the female sexual development in Drosophila melanogaster. In decapods, as no Tra homologues have been identified, the role of Tra‐2 in sexual development is more often discussed accordingly. In the present study, the full‐length cDNA of Tra‐2 of the mud crab Scylla paramamosain (SpTra‐2) was cloned and characterized. The deduced amino acid sequence of SpTra‐2 contained an RNA‐recognition motif (RRM) flanking by two RS‐rich regions, which are the hallmarks of the Tra‐2 proteins. The SpTra‐2 mRNA was highly abundant in the hepatopancreas, muscles and androgenic glands of the male crabs, implying a potential role in male sexual development. The hypothesis was supported by the RNAi experiments, finding that the injection of SpTra‐2 dsRNA in vivo led to a decreased expression of SpIAG, a key gene in crustacean male sexual differentiation. The relationship between SpTra‐2 and SpIAG was further affirmed by eyestalk ablation (ESA) experiments, which caused SpTra‐2 expression earlier than SpIAG expression in both androgenic glands and hepatopancreas. In addition, treatment with SpTra‐2 dsRNA also reduced the mRNA level of SpSxl, but had no effects on SpDmrt expression, suggesting the sex determination system in S. paramamosain is different from that in D. melanogaster.

中文翻译：

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泥蟹Sylla paramamosain中transformer-2基因的分子特征及其在性发育中的作用

Transformer-2（Tra-2）是一种mRNA剪接因子，可与Tra协同调节黑腹果蝇中女性的性发育。在十足动物中，由于未发现Tra同源物，因此更经常讨论Tra-2在性发育中的作用。在本研究中，克隆并鉴定了泥蟹Scylla paramamosain（SpTra-2）的Tra-2全长cDNA 。推导的SpTra-2氨基酸序列包含一个RNA识别基序（RRM），两侧是两个富含RS的区域，这是Tra-2蛋白的标志。该SpTra-2mRNA在雄性蟹的肝胰腺，肌肉和雄激素腺中高度丰富，这暗示着在雄性发育中的潜在作用。该假说得到了RNAi实验的支持，发现在体内注射SpTra-2 dsRNA会导致SpIAG（甲壳动物男性性别分化的关键基因）的表达下降。眼球消融（ESA）实验进一步证实了SpTra-2与SpIAG之间的关系，该实验导致雄激素性腺体和肝胰腺中SpTra-2的表达早于SpIAG的表达。此外，使用SpTra-2 dsRNA进行治疗还降低了SpSxl的mRNA水平，但对无影响SpDmrt表达，提示在性别决定系统S. paramamosain是从在不同的果蝇。