Effect of Water Temperature on Expression Profiles of Sex Differentiation-Related Genes of Mix (XX-XY) Progenies of Mozambique tilapia Oreochromis mossambicus

• Main Authors: Kuan-Huang Liu, 劉冠宏
• Other Authors: Chien-Hsien Kuo
• Format: Others
• Language: zh-TW
• Published: 2010
• Online Access: http://ndltd.ncl.edu.tw/handle/17302700105109717501

碩士 === 國立嘉義大學 === 水生生物科學系研究所 === 98 === The tilapia, a gonochoristic fish with an XX/XY sex-determining system (GSD), provides an excellent model for studing gonadal sex differentiation controlling by temperature (TSD = Temperature Sex Determination). In this study, we report the effects of the temperature during the period of sex differentiation on the growth rate, sex ratio and the gene expression of the Mozambique tilapia (Oreochromis mossambicus). Based on lethal temperature 50 analysis, the tolerance temperature for tilapia larvae were 19.11 ± 1 ℃. Compared the growth rate and sex ratio with exposed to 22 ± 1 ℃、27 ± 1 ℃ and 34 ± 1 ℃, showing that the growth of tilapia is faster in higher temperature, and a significant proportion of males was observed in 34 ℃. But the growth of tilapia is inhibiting and the sex ratio had no difference in cold temperature. In this study, we used quantitive real-time PCR to determine the precise timing of the gonadal expression of 4 genes (cyp19a, cyp19b, sf-1, dmrt1), associated with gonadal sex differentiation. The transcript of cyp19a was no difference at the beginning of sex differentiation period (before 15 days after hatching, dah) between different water temperature, with a marked elevantion in expression there and decreased thereafter in the high temperature. In contrast, the mRNA expression of cyp19a increased after 20 dah, with the maximum at 25 dah, was found in the cold temperature. For the expression of cyp19b, there had significant difference at different water temperature at 10 dah, and had no difference after 15 dah. The mRNA expression of sf-1 had significant difference between different threatments of temperature at 15 dah. It showed the mRNA expression increased at the low temperature, but decreased at the high temperature. The mRNA expression of dmrt1, which presented in both male and female gonad, with no significant difference between different treatments before 20 dah, but the mRNA expression significantly increased after 25 dah in the high temperature. Therefore, suggests an important role for sf-1 and cyp19b in the transcriptional regulation of dmrt1 and cyp19a in the early stage of TSD. Dmrt1 and cyp19a exhibited a lagged expression, suggesting an important role for later stage differentiation.