The mammalian olfactory system utilizes specialized signal transduction components to detect odors. These olfactory genes contain consensus sites for a family of trans-acting factors which includes Olf-1/EBF (O/E-1). The O/E-1 protein is expressed at high level in adult olfactory neurons and transiently during embryogenesis in a variety of other neuronal tissues. The laboratory is actively trying to understand the role of this family of transcription factors in mouse neurodevelopment. We have identified a C elegans homologue of the mammalian O/E-1 protein. We believe that the C elegans homologue of O/E-1 (Ce O/E-1) is encoded by the unc-3
gene, mutations in which are reported to cause all classes of motor neurons in the ventral cord to have disorganized processes and make neuro-muscular junctions at ectopic sites. We have identified point mutations in the Ce O/E-1 coding region for three unc-3
alleles. We have used GFP fusions to the promoter of the Ce O/E-1 protein and specific antibodies to the protein to study the pattern of expression. The Ce O/E-1 protein is expressed as early as bean stage and continues to be expressed in the neurons of the ventral cord and the ASI chemosensory neurons throughout development. These observations are consistent with a similar role for O/E proteins in both mice and nematodes, i.e., these transcription factors play an essential role in the determination of the terminal phenotype of neurons.