PAG-3, A CAENORHABDITIS-ELEGANS GENE INVOLVED IN TOUCH NEURON GENE-EXPRESSION AND COORDINATED MOVEMENT

Mutations in a newly identified gene, pag-3, cause ectopic expression of touch neuron genes mec-7, mec-7lacZ and mec-4lacZ in the lineal sis ters of the ALM touch neurons, the BDU neurons. pag-3 mutants also sho w a reverse kinker uncoordinated phenotype. The first pag-3 allele was isolated in a screen for mutants with altered immunofluorescence stai ning patterns. Two additional pag-3 alleles were identified in a nonco mplementation screen of 38,000 haploid genomes. All of the pag-3 allel es were recessive to wild type and cause the same phenotypes. Two-fact or crosses, deficiency mapping and three-factor crosses located pag-3 to the right arm of the X chromosome between unc-3 and unc-7. Because recessive mutations in pag-3 result in expression of several touch cel l specific genes in the BDU neurons, pag-3(+) must directly or indirec tly suppress expression of these genes in the BDU neurons. Although pa g-3 mutants did not show mec-3lacZ expression in their BDU neurons, ex pression of mec-7lacZ and mec-4lacZ in the BDU neurons of pag-3 mutant s required mec-3(+).