In the EvoInSiDe team, we are addressing this shortcoming using both genomic and embryological approaches in comparative analyses with different animal model systems. Our current investigations include the characterization of the Wnt and Fzd complements from a large variety of different metazoan animals in an effort to retrace the evolutionary history of the Wnt and Fzd families. This project makes use of bioinformatic approaches, such as phylogenetic analyses, genome-wide synteny screens as well as ancestral sequence reconstruction. In parallel, we are also studying the roles of Wnt signaling during development, chiefly in sea urchins and amphioxus. In sea urchins, we have, for example, already characterized the spatiotemporal expression patterns of all Wnt ligands and Fzd receptors from the European species Paracentrotus lividus. We have further established that a specific Wnt/Fzd couple (Wnt6 and Frizzled1/2/7) is required, in this species, for the activation of canonical Wnt/b-catenin signaling in a subset of vegetal blastomeres to establish endodermal cell fate and that another Fzd receptor (Frizzled5/8) controls the initiation of gut invagination, likely through the activation of the non-canonical planar cell polarity pathway.