William Talbot, Ph.D.

Assistant Professor of Developmental Biology

The vertebrate body plan emerges during gastrulation, when cell rearrangements form the three germ layers and signaling interactions establish organ rudiments in their proper positions. We investigate the genetic mechanisms that govern cell fate specification and morphogenesis in the zebrafish embryo. The zebrafish offers a powerful combination of forward genetics and exquisite cellular analysis that is unique among vertebrates: genetic screens have identified thousands of mutations, and the transparent embryo is accessible for single-cell observations and manipulations. Our studies have focused on a dorsal region of the embryo known as the organizer, which sends signals that establish the fates of neighboring cells.

Our goal is to understand patterning events in the early embryo by characterizing mutations that disrupt organizer development. We have shown that the squint gene encodes a Nodal-related TGF-beta family signal that induces organizer development in the early embryo. In addition, our genetic analysis indicates that the mutually repressive interactions among the bozozok, vox, and vent genes are essential to establish the organizer on the dorsal side of the embryo. We are working to understand the interactions among these genes and to identify new genes with important patterning functions in genetic screens and in gene expression profiling experiments. In addition, we are characterizing the maternal pathways that establish the earliest asymmetries in the embryo, leading to patterned expression of zygotic genes such as squint, bozozok, vox, and, vent.