A Measurable increase in oxidative damage due to reduction in superoxide detoxification fails to shorten the life span of long-lived mitochondrial mutants of Caenorhabditis elegans.
SOD-1 and SOD-2 detoxify superoxide in the cytoplasm and mitochondria. We find that, although several long-lived mutants of Caenorhabditis elegans have increased SOD levels, this phenomenon does not correlate with life span or growth rate. Furthermore, although disruption of sod-1 or -2 expression produces numerous phenotypes, including increased sensitivity to paraquat and increased oxidative damage to proteins (except in daf-2 mutants), this fails to shorten the life span of these long-lived mutants. In fact, sod-1(RNAi) increases the life span of daf-2 mutants and sod-2(RNAi) that of clk-1 mutants. Our results suggest that increased superoxide detoxification and low oxidative damage are not crucial for the longevity of the mutants examined, with the possible exception of daf-2, where our results are inconclusive. These results are surprising because several of the long-lived mutants that we examined specifically affect mitochondrial electron transport, a process whose involvement in life-span determination is believed to be related to superoxide generation. We discuss the significance of our findings in light of the oxidative stress theory of aging.
Yang
Wen
W
Department of Biology, McGill University, Montreal, Quebec H3A 1B1, Canada.
Li
Jingjing
J
Hekimi
Siegfried
S
D000818:Animals; D017173:Caenorhabditis elegans / Q000235:genetics* / Q000502:physiology; D050259:Genes, Mitochondrial; D008136:Longevity / Q000235:genetics*; D009154:Mutation; D018384:Oxidative Stress; D013482:Superoxide Dismutase / Q000032:analysis; D000072105:Superoxide Dismutase-1; D013481:Superoxides / Q000378:metabolism*; D000099156:Superoxide Dismutase 2
D013482:Superoxide Dismutase; D000072105:Superoxide Dismutase-1; D013481:Superoxides; D000099156:Superoxide Dismutase 2