Induction of female-to-male sex reversal by high temperature treatment in Medaka, Oryzias latipes.
Medaka, Oryzias latipes, has a firm XX-XY sex-determining system with the sex-determining gene, DMY, on the Y chromosome. However, previous studies have suggested that high water temperature might affect sex determination in Medaka. In the present study, the influence of high water temperature on sex reversal was examined. Fertilized eggs of two inbred strains of Medaka were developed at high water temperature (32 degrees C) until hatching. The hatched fry were kept at normal water temperatures (27 degrees C) until adulthood, and the phenotypic and genotypic sex was examined. As a result, 24% (N=105) and 50% (N=36) of XX fish developed a male phenotype in the Hd-rR and HNI inbred strains, respectively. These XX sex-reversed males had a normal testis and were fully fertile. On the other hand, all XY fish were male in the both strains. These results demonstrate that high water temperatures can induce XX sex reversal and that elevated water temperatures during the embryonic stage is a simple and useful method for getting XX males in Medaka.
Sato
Tadashi
T
Department of Environmental Science, Faculty of Science, Niigata University, Japan. satochu@env.sc.niigata.u-ac.jp
Endo
Tomokazu
T
Yamahira
Kazunori
K
Hamaguchi
Satoshi
S
Sakaizumi
Mitsuru
M
D000818:Animals; D017931:DNA Primers; D005260:Female; D006066:Gonads / Q000033:anatomy & histology; D057850:Hermaphroditic Organisms; D008297:Male; D009990:Oryzias / Q000502:physiology*; D010641:Phenotype; D016133:Polymerase Chain Reaction; D012732:Sex Determination Analysis; D019849:Sex Determination Processes; D013696:Temperature
D017931:DNA Primers