| Budget Amount *help |
¥1,600,000 (Direct Cost: ¥1,600,000)
Fiscal Year 1997: ¥1,600,000 (Direct Cost: ¥1,600,000)
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| Research Abstract |
Mutants in osm-3 gene affecting chemosensory behavior were previously isolated by their failure to avoid high concentrations of salts and sugars that are chemoattractant at lower concentrations. These mutants were later shown to be defective in other chemosensory behaviors such as dauer formation and chemotaxis, and fail to take up fluorescein dyes in a set of chemosensory amphid and phasmid neurons. Cloning of the osm-3 gene by germline transformation rescue of the mutant phenotyope by the wild type genomic DNA revealed that it encodes a 672 amino acid long kinesin like protein (KLP) that shows high homology with the mouse KIF3, and sea urchin KRF85/95 motor proteins. Temporal and spatial expression of the osm-3 : lacZ fusion gene during development is limited to an exclusive set of 26 chemosensory neurons whose dendritic endings are open to the external environment, including six inner labial neurons (IL2), eight pairs of amphid neurons (ADF,ADL,ASE,ASG,ASH,ASI,ASJ,ASK) in the head,
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and two pairs of phasmid neurons (PHA and PHB) in the tail. These results are consistent with the known structural defects in the amphid and phasmid sensilla in osm-3 mutants and reveal novel function of the OSM-3 kinesin in inner labial neurons.
In the bottom-up approach, we started with another member of kinesin family klp-3, cloned by using PCR amplification of the conserved motor domain ATP and microtubule binding sites, and showed that KLP-3 kinesin is a C-terminus motor homologous to the yeast Kar3 and Drosophila ncd kinesins, which have been earlier shown to be involved in chromosomal movement and segregation during meiosis and mitosis. Overexpression of the klp-3 gene partially rescues the lethal phenotype of the maternal lethal him-14 ts(it 44) mutants at non-permissive temperature, and reduces the incidence of males cauused by a non-disjunctional segregation of the sex chromosome. Similarly expression of the klp-3 antisense RNA,under the control of a heat shock promoter causes arrest of the embryonic development, dead eggs and results in polyplold cells in transgenic lines. These observation strongly imply a critical role for the klp-3 function in chromosome segregation. Further analysis of members of the kinesin gene family in C.elegans at genetic and cellular may reveal conserved mechanisms in cellular transport across divergent organisms, including man. Less
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