The proteins of Vent-family and their mRNAs are located in different areas of the tails of Zebrafish and Xenopus embryos

mRNPs: Structure and role in development

In eukaryotic cells, mRNA molecules are coated with numerous RNA-binding proteins and so exist in ribonucleoproteins (mRNPs). The proteins associated with the mRNA regulate the fate of mRNA, including its localization, translation and decay. Before activation of translation, the mRNA does not display any template functions-it is masked. The coordinated activity of certain RNA-binding proteins determines the future fate of each mRNA individually. In embryo development, the temporal and spatial regulation of translation can cause a situation when the mRNA and the encoded protein are localized in different compartments and so the differentiation of the cells can be determined. The fundamentals of regulation of the mRNAs fate and functioning in nerves are similar to those already described for oo- and embryogenesis. Disorders in the mRNA masking and demasking result in the emergence of various diseases, in particular cancers and neuro-degenerative diseases.

Xvent-2 expression in regenerating Xenopus tails

The tail of Xenopus tadpole is an excellent model for appendage regeneration studies. We analyzed the distribution pattern of the transcription factor Xvent-2 mRNA and protein in the beginning of the regeneration of Xenopus tadpole tail stumps after amputation. We revealed the emergence of Xvent-2 mRNA and protein in regeneration bud during the first day after amputation. The data obtained confirm that soon after amputation of the part of the Xenopus tadpole tail, there occurs the emergence of a structure, to some extend, resembling the early embryonic tail bud.

The ved protein patterning in zebrafish embryos

Homeobox transcription factors play an essential role in cells differentiation. The function is realized by the proteins (not by the mRNA) and it is necessary to pay more attention to the protein patterns. In this study we were the first to obtain antibodies against the ved protein, tested their specificity by Western-blot analysis and performed a whole mount immunostaining of zebrafish embryos. It was shown that the spatial-temporal ved protein pattern did not differ from that of other vent-family factors. And moreover, its synthesis like that of vox and vent did not depend on pou5f3.

Expression of vox and vent mRNAs and encoded proteins in zebrafish embryos

In Danio rerio (zebrafish), members of the vent gene-family (vox/vega1, vent/vega2) are considered as ventralizing factors. We investigated not only the expression of their mRNAs by in situ hybridization at different stages of embryonic development, but also the spatial distribution of the encoded proteins by whole-mount immunostaining. We showed vox mRNA to be available in embryos since early cleavage and later on. Vent 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.