Smad2, a receptor-activated Smad, plays a critical role in regulating gametogenesis. In this study, a smad2 homologue was identified and sequenced from ricefield eel ovary cDNA, and its mRNA and protein expression levels were analysed during oocyte development. The cDNA sequence of ricefield eel smad2 consisted of 1863 bp encoding a 467-amino acid protein that had high sequence homology with Smad proteins in other teleosts, especially in Poeciliopsis prolifica. The results of real-time quantitative PCR (RT-qPCR) analysis revealed that smad2 is expressed in the ovary during gonad development, increased continuously until the early vitellogenic stage in the ovaries, and then decreased with ovary maturation. Smad2 protein immunoreactivity was localized in the cytoplasm of follicular cells, oogonia, and primary growth stage oocytes. In vitro experiments revealed that follicle-stimulating hormone (FSH) and human chorionic gonadotropin (hCG) promoted smad2 expression in ovary tissue in a time- and dose-dependent manner, respectively. In summary, Smad2 plays a potentially vital role in ricefield eel ovary development.

Smad2是受体激活的Smad，在调节配子发生中起关键作用。在这项研究中，从稻田鳗鱼卵巢cDNA中鉴定了一个smad2同源物并进行了测序，并在卵母细胞发育过程中分析了其mRNA和蛋白表达水平。稻鳗smad2的cDNA序列由1863 bp组成，编码一个467个氨基酸的蛋白质，该蛋白质与其他硬骨鱼中的Smad蛋白具有很高的序列同源性，特别是在多角藻中。实时定量PCR（RT-qPCR）分析结果显示，smad2在性腺发育期间，它在卵巢中表达，在卵巢中持续增加直至卵黄形成早期，然后随着卵巢成熟而降低。Smad2蛋白的免疫反应性位于卵泡细胞，卵原细胞和初级生长期卵母细胞的细胞质中。体外实验显示，促卵泡激素（FSH）和绒毛膜促性腺激素（hCG）分别以时间和剂量依赖性方式促进卵巢组织中smad2表达。总之，Smad2在稻田鳗鱼卵巢发育中可能起着至关重要的作用。