Gene Expression in Amphibian Development

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Project Summary/Abstract Our goal is to understand early vertebrate development at the molecular level. We study the problem in the frog Xenopus, whose abundant eggs are large and readily manipulated by microinjection and microsurgery. The embryos are large enough to produce material for biochemical and proteomic analysis, and are also ideal for imaging whole embryo morphogenesis, and confocal imaging of explants. During previous grant periods, we have identified potent signaling and signal transduction activities that contribute to embryonic development, neural induction and anterior-posterior patterning of the neural plate. In parallel we improved genome assemblies and annotation for X. tropicalis and X. laevis, enabling a systems level approach. These, and new assemblies for other frogs, not only provide the resources necessary for hypothesis driven research for the community, but also delivered new insights into genome structures, recombination and evolution. In the next grant period, we focus on the genes that control cell shape changes, and tissue level movements in the embryo, focusing on gastrulation and neurulation. Based on the premise that Rho GTP Exchange Factors (GEFs) are often deployed selectively to mediate specific cell behaviors, we will continue our analysis of members of the Plekhg family, among which three of seven show specific morphogenetic defects after CRISPR mediated knockdown, and extend the analysis to other GEFs or GTPase Activating Proteins (GAPs) that show early morphogenetic defects. The results of these experiments will provide basic understanding of normal vertebrate morphogenesis, and insights into the ways that different cellular behaviors are controlled.