Roles of Two Sox9 Genes during Gonadal Development in Japanese Flounder: Sex Differentiation, Spermatogenesis and Gonadal Function Maintenance

• Published in: International journal of molecular sciences Vol. 19; no. 2; p. 512
• Main Authors: Li, Xiaojing, Yu, Haiyang, Wang, Yujue, Liu, Xiaobing, Liu, Yuezhong, Qu, Jiangbo, Wang, Xubo
• Format: Journal Article
• Language: English
• Published: Switzerland MDPI AG 08.02.2018; MDPI
• Subjects: 17α-Methyltestosterone administration; Adaptiveness; Cartilage; Differentiation; dimorphic expression; Fish; Genes; gonadal development; Gonads; Homology; Japanese flounder; Methyltestosterone; Oocytes; Phylogeny; Polymerase chain reaction; Posox9a and Posox9b; Sertoli cells; Sex determination; Sex differentiation; Sox9 protein; Spermatocytes; Spermatogenesis; 17α-Methyltestosterone administration; sex differentiation; Japanese flounder; gonadal development; dimorphic expression; Posox9a and Posox9b
• ISSN: 1422-0067; 1661-6596; 1422-0067
• DOI: 10.3390/ijms19020512

The transcription factor has been implicated in cartilage formation and testis determination in mammals. Here, two duplicates of were found in Japanese flounder ( ) named and , respectively. Phylogenetic and gene structure analyses revealed that and were homologous to that of teleosts and tetrapods. Quantitative real-time polymerase chain reaction (qRT-PCR) showed that both and expressed higher in testis than in ovary of adult tissues. The in situ hybridization (ISH) analysis of gonads showed that and mRNA were both detected in oocytes, Sertoli cells and spermatocytes. During sex differentiation, the expression of exhibited obvious sexual dimorphic expression from 60 days after hatch (dah) with higher expression in male preferred individuals than female preferred individuals and increased gradually from 30 to 100 dah. A similar pattern was detected in expression. After injection of androgen (17α-methyltestosterone) of different concentrations, the expression level of increased significantly, whereas did not change obviously. These results indicated that the two genes of Japanese flounder had converse functions in sex differentiation, whereas their differences in 17α-methyltestosterone administration were obvious and worthwhile for exploring evolutionary and adaptive significance. This study provided a foundation for further exploration of the roles of genes during the sex determination and differentiation, spermatogenesis and gonadal function maintenance of Japanese flounder.