C-ELEGANS OSM-3 GENE MEDIATING OSMOTIC AVOIDANCE-BEHAVIOR ENCODES A KINESIN-LIKE PROTEIN

IN the nematode Caenorhabditis elegans, mutants in osm-3 gene are know n to be defective in osmotic avoidance, chemotaxis and dauer formation behaviours. To study the molecular basis of these pleiotropic defects we have cloned the osm-3 gene by germline transformation of osm-3 (p8 02) mutants through microinjection of the wild type genomic DNA. North ern analysis reveals a 3.0 kb transcript corresponding to osm-3. DNA s equencing of the transforming 4.3 kb fragment revealed a kinesin heavy chain-like protein, which contains conserved ATPase and microtubule b inding domains. Our results are consistent with the previous EM data o n osm-3(p802) mutants that show an accumulation of dense matrix materi al in the amphid sheath cytoplasm and a shortened distal segment of th e amphid channel cilium. These data suggest a kinesin-like role of the osm-3 product in axonal transport.