Expression of and mRNAs and encoded proteins in zebrafish embryos.

In (zebrafish), members of the gene-family (, ) are considered as ventralizing factors. We investigated not only the expression of their mRNAs by hybridization at different stages of embryonic development, but also the spatial distribution of the encoded proteins by whole-mount immunostaining. We showed mRNA to be available in embryos since early cleavage and later on. mRNA appeared after zygotic genome activation only. The vox and vent proteins were revealed at stage of eight blastomeres. At blastula and gastrula the vox and vent protein staining areas completely overlapped those of the mRNAs. They were expressed uniformly throughout the embryo except for a small region of clearing on the dorsal side. From the bud stage throughout somitogenesis, the vox and vent proteins staining progressively covered the embryos except for dorsal side: at the bud stage it resembled that of mRNA and at the beginning of somitogenesis it was clearly seen along the axis structures. At the pharyngula period stages the proteins were located in neural crest zone, but their mRNAs appeared to be in the tail tips. Thus during embryogenesis, the spatial distributions of a protein and its mRNA may not always quite coincide. We observed such mismatches in embryos at the cleavage stage and in the pharyngula period.