Correlations between cell fate and the distribution of proteins that are synthesized before the midblastula transition in Xenopus.

The proteins synthesized before the 512-cell stage by Xenopus blastomeres with different fates were compared by one dimensional PAGE. Blastomeres that contributed more progeny to antero-dorsal axial structures produced proportionately more of two proteins of 225000 and 245000 daltons. Additionally, these proteins were reversibly increased in ventralized embryos and were decreased in dorsalized embryos. These observations indicate that some proteins that are synthesized during cleavage stages are expressed to different degrees in different regions of the embryo, that their expression can be correlated to cell fate in the normal embryo, and that their expression is altered quantitatively in dorsalized and ventralized embryos. The inverse relationship between the production of these proteins and the potential to produce dorsal structures in the normal and in dorsalized/ventralized embryos is consistent with a model in which cell fate is influenced by a gradient of particular proteins.