The main interest of our lab is the regulation of gene expression during the development of sea urchin embryos. We are studying the interaction of different blastomeres in the early embryos, trying to learn how cell interactions lead to induction and cell determination, and how the determined micromeres regulate gene expression and cell behavior to construct the endoskeletal spicule of the larva.
The developing sea urchin embryo generates four micromeres at its vegetal pole during the fourth cell division. These cells form primary mesenchyme, which in turn forms the endoskeletal spicule of the larva. We have developed methods to isolate and purify the spicules, and characterized the organic matrix of the spicules. They are composed of several glycoproteins. We have isolated cDNA clones from an expression vector library that encodes the principal (glyco)protein of the spicule matrix. We are studying the regulation of the expression of this and related genes and are trying to learn more about how the spicule is differentiated and constructed. Recent work utilizes fluorescent labeling and immunoelectron microscopy to follow the import, precipitation, and secretion of calcium and matrix proteins, which form the spicule.