It has been proposed that free radicals, especially those of molecular oxygen, may accelerate aging in animals. To investigate the possible role of oxygen free radicals in aging, mutants of the nematode Caenorhabditis elegans were isolated which are hypersensitive to methyl viologen (paraquat) and oxygen. The free-living nematode is an attractive model system for aging research on metazoans. The nematode offers the great advantages of genetic manipulability, short life span, cellular simplicity, and easy cultivation. Investigation of two genes in C. elegans should serve to illuminate the relationship between oxidative damage and aging. A mutation in one of these genes, mev-1
, has been shown to reduce Cu/Zn superoxide dismutase activity by 30 to 50% relative to wild-type animals. The life spans of this mutant and a second mutant, rad-8
, are significantly shortened in the presence of high oxygen concentration. We suggest that oxygen radicals may be involved in the normal aging in C. elegans.