Intercellular gap junctional channels facilitate the transfer of ions and small molecules, and this form of cell-cell communication is crucial to normal development of the vertebrate embryo. The aim of this proposal is to study gap junction biosynthesis and the developmental role of gap junctional communication in vertebrate embryogenesis, using as a model system the frog Xenopus laevis. Messenger RNAs that may encode a small family of distinct gap junctional subunits are present during oogenesis and early development in this organism. The channel forming properties of these gene products will be investigated. The spatial and temporal patterns of abundance of the gap junction mRNAs and their protein products will be determined. Tests of the developmental functions of gap junctional communication will involve specific destruction of mRNAs in vivo, direct interruption of communication among cells in defined embryonic lineages, and attempts to perturb biosynthesis of new embryonic gap junction proteins with "antisense" RNA. Developmental abnormalities resulting from such treatments will be interpreted in the light of clonal analysis of cell fate changes in treated embryos. %%% The results of this study will shed light on basic modes of cell- cell signalling during embryonic pattern formation and may suggest explanation of common defects in the early development of vertebrates.
