DH @ Illinois

The enormous diversity of cell types in any animal model system is defined by neuron type-specific gene batteries that endow distinct cells with distinct anatomical and functional properties. I will show that the diversity of neuronal cell types in the nematode C. elegans can be reduced to a simpler descriptor, the combinatorial expression of a specific class of transcription factors, encoded by homeobox genes. I propose that the preponderance of homeobox genes in neuronal identity control is a reflection of an evolutionary trajectory in which an ancestral neuron type was specified by an ancestral homeobox genes and that this functional linkage then duplicated and diversified to generate distinct cell types in an evolving nervous system.