Developmental expression of a novel Ftz-F1 homologue, ff1b (NR5A4), in the zebrafish Danio rerio.

The Ftz-F1 genes encode orphan receptors of the nuclear receptor superfamily. The mammalian Ftz-F1 homologue, SF-1, has been found to be essential for the proper development of the adrenal-gonadal axis and it also plays a critical role in mammalian sex-determination. We report here the isolation and characterisation of a novel zebrafish Ftz-F1 gene, ff1b. Whole-mount in situ hybridization revealed onset of expression in the developing rostral diencephalon at 22 h post-fertilization (h.p.f.). Later, at 30 h.p.f., transcripts could be detected in the anterior regions of the pancreatic anlagen. Expression in both locations peaks at 36 h.p.f. and disappears at around 48 h.p.f.