Meiosis is a specialized type of cell division critical for gamete production during sexual reproduction in eukaryotes. The meiotic recombination protein Rec8 has been identified as an important factor in germ cell meiotic initiation in vertebrates; however, its equivalent role in teleosts is poorly characterized. In this study, we cloned and sequenced the rec8 gene from orange-spotted grouper (Epinephelus coioides). The cDNA sequence consisted of 2244 base pairs (bp), including a 5′ untranslated region (UTR) of 198 bp and a 3′UTR of 284 bp. The open reading frame of grouper rec8 was 1752 bp, encoding 584 amino acids. Expression levels of rec8 were higher in the ovary, intersex gonad, and testis. A neighbor-joining phylogenetic tree based on the deduced amino acid sequence indicated a common origin for grouper and other teleost rec8 molecules. Immunohistochemistry using a polyclonal anti-Rec8 antibody localized the protein in the oogonia and primary oocytes in the ovary and in spermatogonia and spermatocytes in the intersex gonad and testis, suggesting that Rec8 may play an important role in the meiotic division and the development of grouper germ cells. In addition, we found that the transcription factor Dmrt1 increased rec8 promoter activity through the second binding site, based on dual-luciferase assays. Together, these results suggest that Rec8 plays a crucial role in meiosis and may be regulated by Dmrt1 to affect meiosis in groupers.

减数分裂是细胞分裂的一种特殊类型，对于真核生物有性繁殖期间的配子产生至关重要。减数分裂重组蛋白Rec8已被鉴定为脊椎动物生殖细胞减数分裂起始的重要因素。但是，它在硬骨鱼中的等效作用的特征很差。在这项研究中，我们克隆并测序了来自橙色斑点石斑鱼（Epinephelus coioides）的rec8基因。cDNA序列由2244个碱基对（bp）组成，包括198 bp的5'非翻译区（UTR）和284 bp的3'UTR。石斑鱼rec8的开放阅读框为1752 bp，编码584个氨基酸。rec8的表达水平卵巢，双性交性腺和睾丸较高。基于推导的氨基酸序列的邻居连接系统树表明石斑鱼和其他硬骨rec8分子的共同起源。使用多克隆抗Rec8抗体的免疫组织化学将蛋白定位于卵巢中的卵黄质和原代卵母细胞以及两性腺和睾丸中的精原细胞和精母细胞，这表明Rec8可能在减数分裂和石斑鱼生殖的发育中起重要作用细胞。此外，我们发现转录因子Dmrt1增加rec8双荧光素酶检测，通过第二个结合位点启动子活性。总之，这些结果表明Rec8在减数分裂中起关键作用，并可能受Dmrt1调节以影响石斑鱼的减数分裂。