Expression of GTP-binding protein gene drg during Xenopus laevis development.

To study the genes which may play a role in the development of the vertebrate central nervous system (CNS) using a subtraction cloning approach, we previously identified a set of novel genes which are predominantly expressed in the mouse embryonic CNS and down-regulated during development. One of these genes, drg, encodes a novel 41 kilodalton GTP-binding protein (DRG), which is highly expressed in the embryonic CNS and shows remarkable evolutionary conservation. To study the biological role of this protein during Xenopus embryonic development, we cloned the Xenopus drg cDNA (Xdrg). The predicted Xenopus DRG protein (XDRG) is more than 95% identical to the mouse DRG. Analysis of Xdrg expression by Northern blots, whole-mount in situ hybridization and RNA-PCR revealed the presence of varying levels of transcript for this gene in embryos and adult tissues. Among the three mRNA species detected by Northern hybridization, two smaller ones show temporally regulated expression patterns during embryonic development.