Cloning of an X. laevis gene expressed during early embryogenesis coding for a peptide region homologous to Drosophila homeotic genes.

A Xenopus laevis gene was cloned on the basis of cross-homology to a region conserved between several Drosophila homeotic genes. It was shown to be expressed during early development, starting at late gastrulation and producing three transcripts under specific temporal control. The frog gene contains a region coding for 60 amino acids, which is extremely conserved when compared to Drosophila homeotic genes in the region of the homeo domain. Southern blot analysis indicates that there are at least five such sequences in the Xenopus genome. The conserved region is very rich in arginine. This gene could perhaps represent the first development-controlling gene identified in vertebrates.