Bej Dilip Kumar, Majhi Sullip Kumar
P.G. Department of Zoology, Fakir Mohan Autonomous College, Balasore, Odisha, India - 756001.
ICAR - Central Inland Fisheries Research Institute, Regional Centre, Guwahati, Assam, India - 781006.
J Genet Eng Biotechnol. 2025 Sep;23(3):100518. doi: 10.1016/j.jgeb.2025.100518. Epub 2025 Jun 11.
The scp3 gene encodes the SYP3 protein, which forms the synaptonemal complex required for pairing homologous chromosomes throughout the prophase of the first meiosis. In addition, it plays a significant role in the formation of germ cells. The 978 bp scp3 mRNA transcript from Hypoatherina tsurugae was cloned and sequenced. The gene comprises an open reading frame (ORF) of 720 bp encoding 240 amino acids (AA), which are identical to those of various other fish species. A phylogenetic tree was created by comparing the mRNA sequences of 50 fish species from the taxa accessible in the NCBI database, utilizing Acipenser ruthenus as an out-group. The tree revealed a higher homology of scp3 from H. tsurugae with Maelanotaenia boesemani, the 2 forming a single clade. Using qRT-PCR, scp3 mRNA transcript expression was investigated and found to be highly expressed in amhy- (females) during the early gonadal differentiation phase, from day 0 to week 10 after hatching. In contrast, amhy+ (males) showed comparatively low expression. The differentiation of male and female gonads was determined six weeks after hatching, based on histological analysis of gonads recovered from biweekly collected larvae throughout the sex determination/differentiation stage. In this phase, primary oocytes are predictable. The data obtained in this study provide crucial information for further understanding the molecular mechanisms involved in sex differentiation and determination in fish.
scp3基因编码SYP3蛋白，该蛋白形成在第一次减数分裂前期同源染色体配对所需的联会复合体。此外，它在生殖细胞的形成中起重要作用。对来自日本下鱵鱼的978 bp的scp3 mRNA转录本进行了克隆和测序。该基因包含一个720 bp的开放阅读框（ORF），编码240个氨基酸（AA），这些氨基酸与其他各种鱼类的氨基酸相同。通过比较NCBI数据库中可获取的50种鱼类的mRNA序列，以俄罗斯鲟作为外群，构建了系统发育树。该树显示，日本下鱵鱼的scp3与博氏美拉诺条鳅的同源性更高，二者形成一个单系分支。使用qRT-PCR研究scp3 mRNA转录本的表达，发现其在孵化后第0天至第10周的性腺分化早期在amhy-（雌性）中高表达。相比之下，amhy+（雄性）的表达相对较低。根据在性别决定/分化阶段每两周收集的幼体中回收的性腺的组织学分析，在孵化后六周确定了雄性和雌性性腺的分化。在此阶段，可以预测初级卵母细胞。本研究获得的数据为进一步了解鱼类性别分化和决定所涉及的分子机制提供了关键信息。
