Gene expression in amphibian embryogenesis.

The study of molecular events during the embryogenesis of Xenopus laevis has advanced as a result of the availability of molecular markers, i.e., nucleic acid and antibody probes for genes that are expressed in a temporally and spatially regulated fashion during development. In this article we summarize results on the localized expression of keratin genes and on the reconstruction of regulated transcription of the gastrula/neurula-specific DG42 gene. Furthermore, we discuss experiments that investigate molecular events during mesoderm induction and provide information on the nature of the inducing principle.