Testicular type Sox9 is not involved in sex determination but might be in the development of testicular structures in the medaka, Oryzias latipes.
Testicular type Sox9 is the most upstream conserved gene in the sex determining cascade among vertebrate. However, in medaka, only one Sox9 gene was identified as expressed in the ovary; no other Sox9 gene was reported expressed in the testis. We explored the medaka genome and cloned a novel testicular type Sox9 cDNA. Phylogenetic analysis revealed that both our isolated Sox9 and the already reportedly cloned medaka Sox9 belongs zebrafish Sox9a branch. Therefore, we named our gene Sox9a2. Unexpectedly, Sox9a2 mRNA was expressed in somatic cells surrounding germ cells at similar high levels in both sexes during early gonadal sex differentiation. However, at the initial stage of testicular tubules development, the expression of Sox9a2 was maintained only in XY gonads, and was remarkably reduced in XX gonads. These results suggest that Sox9a2 is not involved in early sex determination and differentiation, but is involved in the later development of testicular tubules in medaka.
Nakamoto
Masatoshi
M
Department of Environmental System Science, Graduate School of Science and Technology, Shinshu University, Matsumoto 390-8621, Japan.
Suzuki
Aya
A
Matsuda
Masaru
M
Nagahama
Yoshitaka
Y
Shibata
Naoki
N
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D003001:Cloning, Molecular; D017931:DNA Primers; D006609:High Mobility Group Proteins / Q000737:chemistry / Q000235:genetics*; D008297:Male; D008969:Molecular Sequence Data; D009990:Oryzias / Q000196:embryology*; D010802:Phylogeny; D055758:SOX9 Transcription Factor; D017386:Sequence Homology, Amino Acid; D019849:Sex Determination Processes; D013737:Testis / Q000196:embryology* / Q000378:metabolism; D014157:Transcription Factors / Q000737:chemistry / Q000235:genetics*
D017931:DNA Primers; D006609:High Mobility Group Proteins; D055758:SOX9 Transcription Factor; D014157:Transcription Factors