In our lab, we study the signal transduction and transcriptional mechanisms that pattern the vertebrate embryo. The primary focus of our research with the amphibian, Xenopus laevis, is the development of Spemann’s organizer, a specialized group of cells that regulates formation of the body plan, and the development of the primary germ layers that form embryonic mesoderm and endoderm. We are using biochemical, molecular and embryological approaches to address two fundamental questions: 1) What are the signaling and transcriptional regulatory pathways that establish and refine pattern in the gastrula; and 2) How is an individual signal used to generate distinct responses during development? In our studies of organizer formation we have identified a transcriptional cascade of activators and repressors that regulate organizer formation and function. Ongoing studies in this area include the analysis of Siamois, Twin and Goosecoid, homeobox genes required for organizer formation and function. In our studies of germ layer formation, we have identified signals required for mesodermal and endodermal development and have identified genes that regulate the expression of and response to germ layer-inducing signals. Ongoing studies address the role of VegT, a maternal T-box gene, and Nodal-related members of the TGFbeta family, in mesodermal and endodermal development. We are also studying FoxD3 and Sox17, transcription factors that regulate the expression of Nodal genes and the cellular response to Nodal proteins, respectively. The ultimate goal of our work is to identify the critical genes and pathways that establish the major lineages and signaling centers of the vertebrate embryo.