Oxidative stress and life span determination in the nematode Caenorhabditis elegans.

The free radical theory of aging proposes that oxidative stress is one of the determinants of an organism's life span. In Caenorhabditis elegans, genetic or environmental changes have been shown to modulate life span. Here we discuss whether changes in the generation and destruction of free radicals are implicated in these life span modulations. Changes in culture oxygen concentrations that are considered to reflect free radical generation perturb the life span. The life spans under high and low oxygen concentrations were shorter and longer, respectively, than those under normoxic conditions. Short-term exposure to high oxygen concentration lengthens the life span. This is considered to be the result of an increase in antioxidant defense induced by short-term oxidative stress. Mutations in genes such as age-1 and daf-2 that compose the insulin-like signaling network conferred oxidative stress resistance and an increase in Mn-SOD gene expression as well as life span extension.