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GENE REGULATORY VIEW OF THE ORIGIN AND EVOLUTION OF ANIMAL BODY PLANS  E. H. Davidson.  Division of Biology, California Institute of Technology

     Body plans are generated by the process of development and in all complex animals development is driven by the operation of regulatory gene networks.  The central components of those networks consist of the skein of genomic regulatory linkages that connect the cis-regulatory DNA sequences of sets of genes which themselves produce gene regulatory proteins.  The developmental control systems responsible for body plan formation are hardwired, heritable, species-specific features of animal genomes.  They determine in which cells, when, and at what rate each gene is expressed during development.  An example of such a developmental gene regulatory network that is now being unraveled in the sea urchin embryo will be presented.  At a mechanistic level, understanding the evolution of body plans can only be achieved by determining evolutionary changes in the relevant developmental regulatory networks.  To this end a new complex of scientific disciplines is required, rooted in regulation molecular biology, but relying heavily on sophisticated new computational approaches, the accessibility of comparative genomics, and the expert use of both phylogenetic and other evolutionary information together with solid developmental biology.

     (Supported by NASA/Ames NAG2-1368.)