Tracing the emergence of a novel sex-determining gene in medaka, Oryzias luzonensis

• Published in: Genetics (Austin) Vol. 191; no. 1; pp. 163 - 170
• Main Authors: Myosho, Taijun, Otake, Hiroyuki, Masuyama, Haruo, Matsuda, Masaru, Kuroki, Yoko, Fujiyama, Asao, Naruse, Kiyoshi, Hamaguchi, Satoshi, Sakaizumi, Mitsuru
• Format: Journal Article
• Language: English
• Published: United States Genetics Society of America 01-05-2012
• Subjects: Amino Acid Sequence; Animals; Computational Biology; Female; Fertility - genetics; Fish; Fish Proteins - chemistry; Fish Proteins - genetics; Fish Proteins - metabolism; Gene Expression Regulation; Genes; Genomics; Investigations; Male; Molecular Sequence Data; Mutation; Oryzias - genetics; Oryzias - physiology; Sex Characteristics; Sex Chromosomes - genetics; Sex Determination Processes - genetics
• ISSN: 1943-2631; 0016-6731; 1943-2631
• DOI: 10.1534/genetics.111.137497

Three sex-determining (SD) genes, SRY (mammals), Dmy (medaka), and DM-W (Xenopus laevis), have been identified to date in vertebrates. However, how and why a new sex-determining gene appears remains unknown, as do the switching mechanisms of the master sex-determining gene. Here, we used positional cloning to search for the sex-determining gene in Oryzias luzonensis and found that GsdfY (gonadal soma derived growth factor on the Y chromosome) has replaced Dmy as the master sex-determining gene in this species. We found that GsdfY showed high expression specifically in males during sex differentiation. Furthermore, the presence of a genomic fragment that included GsdfY converts XX individuals into fertile XX males. Luciferase assays demonstrated that the upstream sequence of GsdfY contributes to the male-specific high expression. Gsdf is downstream of Dmy in the sex-determining cascade of O. latipes, suggesting that emergence of the Dmy-independent Gsdf allele led to the appearance of this novel sex-determining gene in O. luzonensis.