Four quantitative trait loci (QTLs), discovered by genetic mapping and narrowed through recombination, affect both adult longevity and one or more stress responses in the nematode C. elegans. Each strain differs genetically from the parental strain by 1-3% of the genome, yet differs from it reproducibly and significantly in these phenotypes. In addition, 47 loci are presently known in C. elegans, at which mutations have been reported to extend life, and two dietary interventions (caloric restriction and CoQ deficiency) markedly increase the life spans of wild type strains and some mutants. We propose to study these four new QTLs in parallel with two modified diets and a """"""""longevity panel"""""""" of 14 mutant strains (representing all classes of mutation that confer 1.5- to 3.8-tbld life-extension relative to appropriate controls), for an array of measures indicating their metabolic and antioxidant status.
The Specific Aims are to (1) Narrow the implicated QTL intervals by selecting and testing recombinants that partition them. (2) Assess multiple in rive phenotypes for each longevity locus and the panel of long-lived mutants and diets (with controls): traits include rcsistance to oxidative and other stresses, metabolic activity (02 consumption; production of CO2 and NH3) and lifetime metabolic output, and life span as a function of caloric intake. (3) Assess molecular phenotypes of these loci, including (a) metabolic profiles to measure indices of free radical generation and damage (for the congenic lines and also for the longevity panel), and (b) genc-cxprcssion profiles assessed on microarrays. (4) Assess and confirm candidate-gene functions by the following end-game strategies: (a) phenotypic reversion through transgenic overexpression or RNAi suppression, for alleles differing markedly in transcript levels: (b) sequencing exons of candidate gene in five strains known to harbor allelic polymorphisms for longevity based on mapping; (c) for alleles differing by a transposon insertion, screening for revertants that arise by precise germline excision; and (d) functional assay by rescue of yeast knock-out strains. Genetic variants that affect both longevity and metabolic damage are likely to be conserved in evolution, and will therefore be evaluated in other model organisms. This comparative molecular gerontology strategy may lead to discovery of pathways affecting life span and age-associated diseases in humans, and thus to the alleviation of illness and debility among the aged.
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