INVESTIGADORES
SOMOZA Gustavo Manuel
congresos y reuniones científicas
Título:
Characterization and expression profiles of DMRT1, SF1 and P450aro genes during gonadal sex differentiation in Patagonian pejerrey Odontesthes hatcheri.
Autor/es:
RICARDO HATTORI; JUAN IGNACIO FERNANDINO; CARLOS AUGUSTO STRÜSSMANN; GUSTAVO M SOMOZA; M. YOKOTA; S. WATANABE
Lugar:
Saint Malo, France
Reunión:
Congreso; 8th International Symposium on Reproductive Physiology of Fish.; 2007
Resumen:
BACKGROUND: Temperature sex determination (TSD) has been documented in many fish species. Our understanding of this mechanism is greatly limited by the difficulty in discerning the genotypic sex of embryos/juveniles prior to morphological sex differentiation. In order to redress this problem, our group recently developed a strain of Odontesthes hatcheri, a species with genotypic sex determination (GSD) and TSD at intermediate and extreme temperatures, respectively, that possesses a SNP sex-linked marker. In this study, we used this strain (BBF1) to analyze how some sex differentiation genes are expressed in this species before and during gonadal sex differentiation at a sexually neutral, intermediate temperature. METHODS: The genes SF1, DMRT1, P450aro and AMH of O. hatcheri were cloned, sequenced and their structure analyzed. Their expression levels during gonadal differentiation and early development (from 0 to 7 weeks after hatching, or wah) at 21ºC were then analyzed by Real-Time RT PCR. In all samples, RNA was isolated only from the trunk whereas the caudal portion was used for DNA extraction and sex genotyping using a PCR-based SNP marker specific to the strain. RESULTS: O. hatcheri had one single copy each of SF1, P450aro and AMH but three DMRT1 isoforms originated by differential splicing: DMRT1a, DMRT1b and DMRT1c. The expression profiles of the three DMRT1s were not sexually dimorphic during the period analyzed. AMH, in contrast, showed upregulation in males from 1wah while P450aro showed upregulation in females from 2wah. SF1 was equally regulated in both sexes, but the expression pattern from 2wah to 4wah (with an apparent peak at 3wah) mimicked those of AMH and P450aro. CONCLUSION: Three isoforms of DMRT1 were identified in O. hatcheri but the function of each variant during gonadogenesis remains to be elucidated. The differential expression of P450aro and AMH genes soon after hatching indicates that sex in this species is probably determined soon after or even before hatching and that these genes may play an import role during gonadal differentiation since ovaries and testes become histologically distinguishable at the fourth week. The similar expression of SF1 with AMH and P450aro genes is consistent with a regulatory mechanism of SF1 over AMH and P450aro genes as described for some fishes and mammals.