| Budget Amount *help |
¥6,200,000 (Direct Cost: ¥6,200,000)
Fiscal Year 1993: ¥2,100,000 (Direct Cost: ¥2,100,000)
Fiscal Year 1992: ¥4,100,000 (Direct Cost: ¥4,100,000)
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| Research Abstract |
The fluoride-resistant (flr) mutations of the nematode C.elegans are all recessive and consist of two classes. Class 1 mutations (flr-1, flr-3 and flr-4) confer strong resistance and slow growth on worms, whereas class 2 mutations (flr-2 and flr-5) confer weak resistance, keep the growth rate unchanged and suppress the slow-growing phenotype of class 1 mutations. In this study we mapped the class 2 mutations and made heterozygotes between either of these mutations and a deficiency including it. The phenotypes of the heterozygotes showed that all the class 2 mutations are hypomorphs or null mutations. We also performed complementation tests between the flr mutations and some known mutations, which confirmed that they map in new genes. The flr genes probably act in neural functions, because mutations in these genes affect formation of dauer larvae under certain circumstances. We cloned two of the flr genes, flr-1 and flr-3, and their cDNA (incomplete length). Sequencing studies showed th
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at the deduced amino acid sequence of flr-1 has weak homology to some ion channels, whereas flr-3 most probably codes for a protein kinase of a new family. Since we obtained two kinds of flr-3 cDNAs differing in the 5' region, the expression of flr-3 may be regulated by alternative splicing.
The "clr-1-like" mutations are defined as larval lethal mutations that cause detachment of the outer surface of the intestine from the inner surface of the body wall. They map in known signal-transduction genes (let-23, let-341, let-60, lin-45, sem-5, lag-2, clr-1 etc.) and unknown genes. We think the latter genes are members of the signal-transduction systems, or they act in cell-differentiation or cell-functions downstream to the signal-transduction systems. In this study we cloned a 4.4kb DNA fragment that contains let(ut102), one of the unknown genes for the clr-1-like mutations. We are sequencing the clone, but homology to known genes has not been detected so far. We plan to study the position of expression of the gene in worms to look for the target of the lethal mutation. We will also search for the relation between the let(ut102) gene and known signal-transduction systems by checking change of its expression by signal-transduction mutations and by testing suppression of the mutations by microinjection of the clone into the mutant worms. Less
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