College of Marine Sciences, South China Agricultural University, Guangzhou, 510642, People's Republic of China.
Guangdong Laboratory for Lingnan Modern Agriculture, Guangzhou, 510642, People's Republic of China.
Fish Physiol Biochem. 2021 Apr;47(2):393-407. doi: 10.1007/s10695-020-00920-7. Epub 2021 Feb 5.
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.
减数分裂是一种特殊的细胞分裂类型，对于真核生物有性生殖中的配子生成至关重要。减数分裂重组蛋白 Rec8 已被确定为脊椎动物生殖细胞减数分裂起始的重要因素；然而，其在硬骨鱼中的等效作用尚未得到充分描述。在这项研究中，我们从橙点石斑鱼（Epinephelus coioides）中克隆并测序了 rec8 基因。cDNA 序列由 2244 个碱基对（bp）组成，包括 5'非翻译区（UTR）198 bp 和 3'UTR 284 bp。石斑鱼 rec8 的开放阅读框为 1752 bp，编码 584 个氨基酸。rec8 的表达水平在卵巢、两性性腺和睾丸中较高。基于推导的氨基酸序列构建的邻接聚类系统发育树表明，石斑鱼和其他硬骨鱼 rec8 分子具有共同的起源。使用多克隆抗 Rec8 抗体进行免疫组织化学定位，在卵巢中的卵原细胞和初级卵母细胞以及两性性腺和睾丸中的精原细胞和精母细胞中定位了该蛋白，表明 Rec8 可能在减数分裂和石斑鱼生殖细胞发育中发挥重要作用。此外，我们发现转录因子 Dmrt1 通过第二个结合位点增加了 rec8 启动子的活性，这是基于双荧光素酶测定。总之，这些结果表明 Rec8 在减数分裂中发挥着关键作用，并且可能受到 Dmrt1 的调控，以影响石斑鱼的减数分裂。
