Worm Breeder's Gazette 13(5): 86 (February 1, 1995)
These abstracts should not be cited in bibliographies. Material contained herein should be treated as personal communication and should be cited as such only with the consent of the author.
|1||Laboraotry of Molecular Biology, Toyohashi University of Technology, Japan 441.|
|2||Protein Engineering Research Institute, Osaka 565, Japan|
Previously three genetic loci osm-3, unc-104, and unc-116 have been described in C. elegans which encode anterograde motor kinesin proteins 3. We have now determined the complete structure of the osm-3 gene which encodes a kinesin like protein of 672 amino acids. OSM-3 consists of all three functional domains generally found in kinesin heavy chain proteins, including an amino terminal globular motor region containing an ATP binding site, an alpha helical coiled coil rod region, and a globular tail domain located at the carboxyl terminus. The OSM-3 kinesin shows homology in both the motor and rod domains with kinesins from divergent species such as mouse KIF3, and sea urchin KRP95, and also with the rod domains of several non kinesin proteins, such as myosin, ezrin, outer membrane alpha precursor OMPA, yeast intracellular protein transport USO1, and the rat neurofilament NF-H. Temporal and spatial expression pattern of the osm-3 gene was determined by using the 1.9 kb osm- 3 promoter region from a 4.5 kb genomic fragment that can rescue the osm-3 mutant phenotype in germline transgenic animals. An osm-3::lacZ fusion gene was constructed in the pPD22.11 expression vector (A. Fire), which included the nuclear localization signal. Histochemical staining of transformants revealed that the fusion gene expression is limited to an exclusive set of 26 chemosensory neurons whose dendritic endings are open to the outside environment through a hole in the animal's cuticle. These include six IL2 neurons of the inner labial sensilla, eight pairs of amphid neurons (ADF, ADL, ASE, ASG, ASH, ASI, ASJ, and ASK) in the head, and two pairs of phasmid neurons (PHA, and PHB) in lumbar ganglia in the tail. Ultrastructurally the osm-3(P802) mutant has a shortening of the distal tip of the amphid neurons, but a normal structure of the IL2 neurons. An even more intriguing observation concerns with the temporal expression of the fusion gene, as staining of IL2 and amphid and phasmid neurons can be seen in early larval stages (L1-L2); however, in late larval and adult stages the staining of amphid neurons completely disappears, but continues in the IL2 and phasmid neurons with the same intensity as observed in early larval stages, suggesting that the osm-3 gene is differentially expressed in all three different chemosensory sensilla. We are now interested in examining the normal and ectopic expression of the osm-3 gene in a variety of mutants altered in sensory and other behaviors. We thank A. Coulson, A. Fire, R., Horvitz, J. Miwa, T. Sano, for help in this work. (References: 1: Shakir et al., 1993; 2: Otsuka et al., 1991, Hall and Hedgecock, 1991; 3: Patel et al., 1993; 4: Perkins et al. 1986)