Genes and mechanisms involved in early embryonic development in Xenopus laevis

Our laboratory is studying genes involved in the regulation of the balance between cell growth and differentiation during embryonic development in Xenopus. We have analyzed the developmental expression of the proto-oncogenes c-myc, and KiRas 2B, the proliferating cell nuclear antigen (PCNA), and the tumor suppressor gene p53. These genes, usually expressed during cell proliferation, are expressed in the oocyte in large quantities, but the majority of their maternal RNAs are degraded by the gastrula stage. The expression of c-myc and the localization of the protein indicate that c-myc has the characteristics expected for a gene involved in the regulation of the mid-blastula transition, when zygotic expression is turned on in the embryo. Its expression during late development or during regeneration indicates that it enables the cells to remain competent for cycling during organogenesis. In vitro systems that reproduce the principal cellular functions during early development are used as model systems to understand the mechanisms involved in early embryogenesis.