Molecular cloning, characterization and expression analysis of Sox9a and Foxl2 genes in half-smooth tongue sole (Cynoglossussemilaevis)

Two transcription factors, Sox9a and Foxl2 were cloned from half-smooth tongue sole (Cynoglossus semilaevis). Sox9a is a new duplication of C.semilaevis Sox9 gene. The complete cDNA of Sox9a gene was 1 842 bp long coding for 487 amino acids and Foxl2 gene was 1 817 bp coding for 308 amino acids. Sox9a was expressed higher in male brain, pituitary and gonad and Foxl2 were higher in female brain, pituitary and gonad. The expression of Sox9a gene in gonads of neo-males was higher than that of normal females. Sox9a and Foxl2 were expressed higher in gastrula stage than in other stages. In the period of sex differentiation, the expression of Sox9a was first going up and then going down and Foxl2 was higher expressed at 37 dph. The highest expressions of Sox9a and Foxl2 genes occurred in nine-month and 12-month old gonad tissues, respectively. Sox9a gene was considered to have inevitable links with sex reversal, sex differentiation and cell differentiation of embryos and formation of spermatogenic cells. Foxl2 was considered to play a role in sex differentiation, cell differentiation of embryos but not to be necessary for sex determination and sex reversal.