IDENTIFICATION OF TGF-BETA-RELATED GENES IN THE EARLY CHICK-EMBRYO

Transforming growth factor-beta (TGF-beta)-related genes have been pos tulated as possible mesoderm inducers in lower vertebrates. Activin, a member of the TGF-beta family has been recently suggested to be direc tly involved in the induction of axial mesoderm in frogs and birds. No dal, a novel TGF-beta-like gene, seems to be essential for mesoderm fo rmation in mice. In this work we have tried to characterize which grow th factors of the TGF-beta family are involved in the initial stages o f differentiation of the chick embryo. Using degenerate primers to spe cific regions of the TGF-beta super family in polymerase chain reactio ns (PCR), we have identified both TGF-beta(2) and TGF-beta(3) transcri pts in early stages of chick development. In addition, we have identif ied a new gene which is transcribed during early chick development. We have called this gene Vgc1 since it is probably the chick homologue o f the mouse Vg-related gene Vgr1. RNA coding for the Vgc1 gene was det ected by RNAse protection in early stage X blastoderms, gastrula and 3 -day-old embryos. In situ hybridization experiments further indicate t hat Vgc1 RNA is distributed uniformly throughout the various regions o f the chick gastrula. The role of Vgc1 in early chick development rema ins to be established.