Expression profile of dmrt1, Amh and Sox9 during the Thermolabile Sex Differentiation Piriod in Pejerrey, Odontesthes bonariensis.

JUAN IGNACIO FERNANDINO; STÜSSMANN, C.A.; MANUEL SOMOZA, GUSTAVO

Kona, Hawaii

Simposio; 4th International Symposium on Vertebrate Sex Determination. Oral presentation.; 2006

The first signs of sex differentiation as determined by histology were found at weeks 7 and 6 for females at 17°C and 25°C, respectively, and weeks 7 and 6 for males at 25°C and 29°C, respectively. At the end of the experiment the percentages of females were 100%, 55%, and 0% at 17°C, 25°C, and 29°C, respectively. The expression of dmrt1 increased after week 4 at 29°C whereas at 17°C it remained low throughout the study (Fig. 1). Approximately 50% of the larvae at 25°C showed increased dmrt1 expression from week 5. Sox9 showed a significant increase at week 5 at 29°C and a significant decrease at week 6 at 17°C. No clear pattern of expression was observed at 25°C but some individuals showed higher Sox9 expression after 5 weeks at this temperature. AMH showed peaks of expression at 5 weeks at both 17°C and 29°C, but the expression at the higher temperature was twofold that at the lower one at peak values (Fig. 2). At 25°C, the expression profile of AMH showed an increase until 4 weeks followed by further increases or decreases depending on the individual. In conclusion, dmrt1 and AMH appear to be involved in testicular differentiation in pejerrey whereas a clear role for Sox9 in sex differentiation could not be established in this study.