Characterization and expression profile of the ovarian cytochrome P450 aromatase (CYP19A1) gene during the thermolabile sex determination period in pejerrey, Odontesthes bonariensis.

KARUBE, M.; FERNANDINO, J.I.; STROBL MAZZULLA, P.H.; STRÜSSMANN, C.A.; YOSHIZAKI, G.; SOMOZA, G.M.; PATINO, R.

JOURNAL OF EXPERIMENTAL ZOOLOGY

WILEY-LISS, DIV JOHN WILEY & SONS INC

Año: 2007 vol. 307 p. 625 - 636

0022-104X

Cytochrome P450 aromatase (cyp19) is an enzyme that catalyzes the conversion of androgens to estrogens and may play a role in temperature-dependent sex determination (TSD) of reptiles, amphibians, and fish. In this study, the ovarian P450 aromatase form (cyp19A1) of pejerrey Odontesthes bonariensis, a teleost with strong TSD, was cloned and its expression profile evaluated during gonadal differentiation at feminizing (17ºC; 100% females), mixed-sex producing (24 and 25ºC; 73.3% and 26.7% females, respectively), and masculinizing (29ºC; 0% females) temperatures. The deduced cyp19A1 amino acid sequence shared high identity (>77.8%) with that from other teleosts but had low identity (<61.8%) with brain forms (cyp19A2), including that of pejerrey itself. The tissue distribution analysis of cyp19A1 mRNA in adult fish revealed high expression in the ovary. Semi-quantitative RT-PCR analysis of the bodies of larvae revealed that cyp19A1 expression increased prior to the appearance of the first histological signs of ovarian differentiation at the feminizing temperature but remained low at the masculinizing temperature. The expression levels at mixed-sex producing temperatures were bimodal rather than intermediate, showing low and high modal values similar to those at the feminizing and masculinizing temperatures, respectively. The population percentages of high and low expression levels at intermediate temperatures were proportional to the percentage of females and males, respectively, and high levels were first observed at about the time of sex differentiation of females. These results clearly implicate cyp19A1 in the process of ovarian formation and possibly also in TSD of pejerrey.