Oxygen-dependent perturbation of life span and aging rate in the nematode

The effects of atmospheric oxygen on the life span and aging rate of the nematode Caenorhabditis elegans were examined. The mean and maximum life spans of both the wild type and mev-1(kn1) mutant, whose cytoplasmic superoxide dismutase activity level is about half of the wild type, were increased and decreased under low and high concentrations of oxygen, respectively. The Gompertz component, a parameter of aging rate, of the wild type was smaller under 1% oxygen than under 2% or more oxygen. Further, the Gompertz component of the mutant increased with an increase in oxygen concentration. These effects of oxygen on the perturbation of life span and aging rate were more pronounced in the mev-1(kn1) mutant than in the wild type. The oxygen-dependent perturbation of life span and aging rate seems to be enhanced by a genetic defect of the mutant in antioxidant defense. A 1% oxygen exposure at the early phase of life span was ineffective for life span extension in the mutant, suggesting that the effect of oxygen concentrations on life span is not secondary to the effects of development and maturation. These results show that changes in oxygen concentration perturb aging rate, and hence oxygen is involved in the specification of life span of the nematode.