Our laboratory investigates mechanisms of cell fate specification and patterning along the animal–vegetal (A–V) axis of the sea urchin (Strongylocentrotus purpuratus) embryo. We have recently shown that correct patterning of endomesoderm cell fates depends on tightly regulating the ratio of the mutually antagonistic transcriptional regulators, SoxB1 (Kenny et al., 1999) and nuclear Β-catenin (Logan et al., 1999), in vegetal blastomeres (Kenny et al., 2003). Clearance of SoxB1 is essential and involves both repression of transcription and spatially regulated turnover of SoxB1 protein (Angerer et al., 2005). To understand this critical early step in cell fate specification, we will pursue the molecular mechanism by which SoxB1 antgonizes nuclear b-catenin and, conversely, the pathways that lead from nuclear b-catenin to SoxB1 transcriptional repression and protein degradation.

A second major focus of our research is to determine how cells at the extreme animal pole, which constitutes the neurogenic region, are specified. This region is a unique transcriptional territory (Angerer and Angerer, 2001). Most cells of the presumptive ectoderm receive b-catenin-dependent signals that divert them to epidermal fates and suppress neurogenesis; in the absence of these signals, the apical pole domain expands. Using molecular screens and candidate gene approaches, we are assembling components of a neurogenic gene regulatory network.

Finally, we have created whole genome databases and computational tools for rapid retrieval of genomic information. Using predicted peptide sequences, we are creating whole genome microarrays for expression profiling.