Protein synthesis in interspecies hybrid embryos of the amphibian Xenopus

The newly synthesized abundant proteins of early Xenopus laevis and Xenopus borealis embryos have been examined by two-dimensional electrophoresis after labelling with [³⁵S]methionine. Six prominent polypeptides specific to Xenopus laevis embryos and a further six specific to Xenopus borealis have been identified. Overall, embryos of the two species are estimated to differ by approx. 15% in their protein synthetic patterns from blastula to tailbud stage. Interspecific hybrid embryos (Xenopus laevis (♀)/Xenopus borealis (♂)) synthesise only the maternally specified set of proteins until gastrulation after which they produce the full complement of both Xenopus laevis and Xenopus borealis specific proteins. The possible use of such molecular markers of parental genome activity in facilitating further embryological study is discussed.