A fork head/HNF-3 homolog expressed in the pharynx and intestine of the Caenorhabditis elegans embryo.

We have cloned a member of thefork head/HNF-3 family of transcription factors from the nematodeCaenorhabditis elegans.Within the predicted DNA binding domain, this gene, calledCe-fkh-1,is 75–78% identical to theDrosophila fork headand rat liver HNF-3 α, β, and γ genes.Ce-fkh-1mRNA is highly enriched in embryos. TheCe-fkh-1gene produces three major transcripts: the longest mRNA retains its original 5′-end but two shorter mRNAs aretrans-spliced at the beginning of exons 2 and 3, respectively.In situhybridization and transgenicCe-fkh-1::lacZreporter constructs indicate that theCe-fkh-1gene is expressed in both pharynx and intestine of the embryo, beginning at the midproliferation stage. A second phase ofCe-fkh-1expression occurs in cells of the larval somatic gonad. The pharynx–gut expression ofCe-fkh-1in theC. elegansembryo is compared with expression offork headthroughout the gut ofDrosophilaembryos and with expression of HNF-3 (αβγ) in the endoderm of mammalian embryos. Such conserved patterns of gene expression point to universal features of gastrulation and of digestive tract formation.