Abstract: 327

EXPRESSION OF ORPHAN NUCLEAR RECEPTORS FTZ-F1 AND SF-1/Ad4BP IN THE DEVELOPING GONAD OF FROGS.

M. Takase^{1 *}, N. Nakajima^{1 *}, K. Kawano¹ , I. Imura^{1 *}, Masahisa Nakamura^{1 *}
Lab for Amphibian Biol, Fac of Sci, Hiroshima Univ, Higashi-Hiroshima , Japan ¹

In vertebrates, the sex-determining and differentiating genes have been isolated. The mechanisms for these processes, however, are not understood yet. SF-1/Ad4BP is required for gonadal development in mice, and is the homologue of Drosophila FTZ-F1 regulating the expression of fushi tarazu homeobox gene during embryonic development. In this study, the expression of FTZ-F1 and SF-1/Ad4BP was studied in the developing gonad of the frog, Rana rugosa. We succeeded in isolating frog SF-1/Ad4BP and FTZ-F1 cDNAs. The amino acid sequence of SF-1/Ad4BP shared 67% identity with that of FTZ-F1. The DNA-binding domain (HMG box) of SF-1/Ad4BP, however, had 95% identity with that of FTZ-F1. By in situ hybridization analysis, the expression of SF-1/Ad4BP was first observed in the developing gonad of tadpoles at st. V, and then lost at st. XX. SF-1/Ad4BP mRNA was detected again in somatic cells in the testis, but not in the ovary, of adult frogs. FTZ-F1 was expressed in embryos at st. 9. FTZ-F1 mRNA was seen in interstitial cells and spermatogonia in the testis, and in oocytes in the ovary. Immunostainings were also evident in these cells. In conclusion, SF-1/Ad4BP and FTZ-F1 are differently expressed in the developing gonad of frogs. SF-1/Ad4BP is probably responsible for the differentiation of somatic cells in the frog testis, while FTZ-F1 for development and differentiation of both germ and somatic cells.

    This abstract is being presented on Monday, August 2 at 8:00 AM to 10:15 AM at CUB 2nd Floor Ballroom.