To gain a better understanding of the gene sets that are expressed in and required for the functions of specific sensory neuron types, our lab utilized a previously described C. elegans primary cell culture technique (1) coupled with FACS sorting to obtain enriched collections of single neuron types. We extracted RNA from these populations and hybridized to the C. elegans Affymetrix Genechips to compare the gene expression profiles of the aversive olfactory neuron type, AWB, and the primary thermosensory neuron type, AFD. We identified a list of approximately 250 genes with at least a 2 fold change in one neuron type as compared to the other. The expression predictions were further validated via real-time PCR and in vivo expression analyses using gfp fusion constructs. Expression patterns of several genes were confirmed by green fluorescent protein (gfp) fusion constructs. Genes analyzed represent a diverse array of gene families encoding sensory receptors, kinases, and transcription factors. We have further characterized a subset of genes identified in these experiments (also see abstract by Brown et al). In particular, we have shown that
dac-1 , the C. elegans dachshund homolog, is expressed in AFD, as well as weakly in the neurons ASK, ASE, and AWC. dachshund belongs to the SKI/SNO family of proteins, and encodes a nuclear factor involved in the development of several organ types, including the Drosophila eye. Interestingly, a
dac-1 knockout allele,
dac-1(
gk211) , exhibits a cryophilic phenotype when placed on a linear temperature gradient, similar to
ttx-1 , an Otd/otx transcription factor required for AFD development. This implicates
dac-1 in the development and/or function of the AFD thermosensory neurons. These experiments validate the use of cell culture and microarrays in C. elegans to identify new genes required for development and function of specific neuronal subtypes. Current experiments are aimed at further analyzing the functions of genes identified by these experiments, and application of this technology to identify genes expressed in additional sensory neuron types. 1.) Christensen M, Estevez A, Yin X, Fox R, Morrison R, McDonnell M, Gleason C, Miller DM 3rd, Strange K. (2002). A primary culture system for functional analysis of C. elegans neurons and muscle cells. Neuron 33, 503-14.