Expression Analysis of <b><i>sox3</i></b> during Testicular Development, Recrudescence, and after hCG Induction in Catfish, <b><i>Clarias batrachus</i></b>

Abstract

In teleosts, the expression of steroidogenic enzymes and related transcription factor genes occurs in a stage- and tissue-specific manner causing sexual development. The role of sox3, an evolutionary ancestor of SRY, has not been studied in detail. Therefore, the full-length cDNA of sox3 (1,197 kb) was cloned from catfish testis, and mRNA expression was analyzed during gonadal development, during the seasonal reproductive cycle, and after human chorionic gonadotropin (hCG) induction. Tissue distribution analysis showed that sox3 expression was higher in testis, ovary, and brain compared to other tissues analyzed. Developing and mature testis showed higher sox3 expression than ovary of corresponding stages, and more sox3 transcripts were found during the spawning phase of the seasonal reproductive cycle. Expression of sox3 was upregulated by hCG after in vivo and in vitro induction, suggesting that gonadotropins might stimulate it. In situ hybridization and immunohistochemistry showed the presence of sox3 mRNA and protein in somatic and interstitial cell layers of the testis. Sox3 could also be found in the zona radiata of developing and mature oocytes. Exposure of methyltestosterone (1 µg/l) and ethinylestradiol (1 µg/l) for 21 days during testicular development showed lower sox3 expression levels in the testis and brain, indicating a certain feedback intervention. These results suggest a possible role for Sox3 in the regulation of testicular development and function.

Molecular cloning and expression analysis of Sox3 during gonad and embryonic development in Misgurnus anguillicaudatus

“…All of these results suggest that Sox3 is critical for neural development in vertebrates (McAninch and Thomas, 2014). Sox3 is reported to be an analog of SRY in testis and associated with mammalian testis development and differentiation (Rajakumar and Senthilkumaran, 2014). Also, Sox3 has been found to be associated with male sex differentiation in Oryzias dancena (Takehana et al, 2014).…”

“…The GenBank accession numbers are as follows: Homo sapiens: Sox1, NP_005977.2;Sox2,NP_003097.1;Sox3,NP_005625.2;Sox14,NP_004180.1;Sox21,NP_009015.1;Mus musculus: Sox1,NP_033259.2;Sox2,NP_035573.3;Sox3,NP_033263.2;Sox14,NP_035570.1;Sox21,NP_808421.1;Gallus gallus: Sox1,NP_989664.1;Sox2,NP_990519.2;Sox3,NP_989526.1;Sox14,NP_990092. fate determination and differentiation (Dee et al, 2008). In Clarias batrachus, dynamic expression pattern of Sox3 in the gonad confirms its potential role in development and germ cell differentiation (Rajakumar and Senthilkumaran, 2014). To further investigate the evolution and functions of Sox3 in fish development, we decided to analyze the role of Sox3 in critical developmental processes, including sex determination and differentiation processes.…”

Molecular cloning, characterization, and expression profiles of the Sox3 gene in Chinese loach Paramisgurnus dabryanus

“…For example, Sox3 has been found to be associated with male sex differentiation in Oryzias dancena (Indian ricefish, Takehana et al, 2014). In various fish species, diverse expression profiles reveal a distinct role Sox3 protein in either testicular or ovarian development, such as redspotted grouper, black porgy, and catfish (Lao, Zhou, Wang, Xia, & Gui, 2007;Rajakumar & Senthilkumaran, 2014;Shin et al, 2009). In the present study, PdSox3 is highly expressed in the ovary and testis.…”

“…In mice, a gain of function mutation of Sox3 in the uncommitted XX gonad results in male sex reversal (Sutton et al, 2011). In fish, such as in red-spotted grouper, in black porgy, and in catfish (Gao et al, 2015;Rajakumar & Senthilkumaran, 2014;Shin, An, Park, Jeong, & Choi, 2009;Yao, Zhou, Wang, Xia, & Gui, 2007), the diverse expression profiles of Sox3 reveal distinct roles, mainly in testicular or ovarian development. In fish, such as in red-spotted grouper, in black porgy, and in catfish (Gao et al, 2015;Rajakumar & Senthilkumaran, 2014;Shin, An, Park, Jeong, & Choi, 2009;Yao, Zhou, Wang, Xia, & Gui, 2007), the diverse expression profiles of Sox3 reveal distinct roles, mainly in testicular or ovarian development.…”

“…In contrast, a loss of function mutation blocks early spermatogenesis in the postnatal germ cells in the testis (Raverot, Weiss, Park, Hurley, & Jameson, 2005). In fish, such as in red-spotted grouper, in black porgy, and in catfish (Gao et al, 2015;Rajakumar & Senthilkumaran, 2014;Shin, An, Park, Jeong, & Choi, 2009;Yao, Zhou, Wang, Xia, & Gui, 2007), the diverse expression profiles of Sox3 reveal distinct roles, mainly in testicular or ovarian development. The exact functions of the Sox3 gene have not been documented in teleost fish.…”