How does gene circuitry specify and pattern embryonic development?
What is the nature of the events set in motion by the expression of a single developmental “master regulator”? Is there a common set of optimal regulatory interactions (rules), analogous to evolutionarily conserved master regulatory genes, which operate among the targets of master regulators to enable developmental robustness and evolvability? To address these questions we are studying the activity of pal-1 , the C. elegans Caudal homolog, an ancient homodomain protein that specifies and patterns posterior development in animals. In C. elegans pal-1 is necessary and sufficient to specify the identity of the C blastomere, a posterior cell in the 8-cell embryo, and then to control its subsequent development or cell lineage. Our goals are to generate a systems-level description of the gene circuitry (network topology) initiated by pal-1 activity and then to infer and test functional units (modules) that enable pal-1 to robustly specify posterior development. We have used microarrays, repo
