Paternal gene expression in developing hybrid embryos of Xenopus laevis and Xenopus borealis.

We have studied protein synthesis in the viable hybrid Xenopus laevis (female) X Xenopus borealis (male) using 2D gel electrophoresis. Fourteen borealis-specific proteins were studied. Two of these proteins appeared by the gastrula stage, five in the gastrula and the rest later. Where homologous laevis proteins were tentatively identified, androgenetic haploid hybrids were used to study whether the protein was encoded by stored maternal mRNA, and how long this mRNA persisted. The two proteins appearing in blastulae were probably initially coded by stored maternal mRNA. This was not detectable by the tailbud-tadpole stage, and presumably had been destroyed.