Fushi tarazu transcription factor-1 (FTZ-F1), a member of a nuclear hormone receptor superfamily, is a transcriptional regulator for fushi tarazu gene expression in Drosophila (Ueda et al., '90). We have cloned a homologue (rrFTZ-F1α) of the FTZ-F1 gene of the frog Rana rugosa. The gene, in frogs, has been shown to have high expression level in the testis (Nakajima et al., 2000). In this study, the RT-PCR analysis showed that the FTZ-Flα mRNA level in adult frogs did not change throughout the year, even during hibernation. However, when immunohistological studies using the anti-rrFTZ-F1α antibody were employed to examine which testicular cells expressed this gene, Sertoli cells were found to produce rrFTZ-F1α in the two seasons - the breeding season (from March through May) and the pre-hibernating season (from October through November). Interstitial cells, however, did it in only the breeding season (from April through May). Taken together, the results suggest that the rrFTZ-F1α expression is regulated at the post-transcriptional step, and that the rrFTZ-F1α may play an important role(s) in the seasonal activities of Sertoli and interstitial cells in the frog testis.
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