The Effect of SOD‐1 Deficiency and Manganese Supplementation on Oxidative Stress Resistance in Caenorhabditis elegans

Oxygen free radicals (ROS) are by‐products of normal metabolism in oxygen utilizing organisms. ROS can cause damage to living cells if not removed quickly. Superoxide dismutases (SODs) are antioxidant enzymes that form the first line of defense against ROS. Not much is known about the five forms of SOD in the roundworm Caenorhabditis elegans ( C. elegans ). The goals of this study are to determine which SODs are essential for oxidative stress resistance and to know if manganese (Mn) supplementation could enhance resistance against oxidative stress. Wild type and individual SOD mutant worms were cultured in growth medium containing various concentrations of paraquat (a ROS generator), and survival was scored twenty hours later. Our results show that only sod‐1 (encodes SOD‐1, a CuZn‐containing SOD) mutant worms are significantly more sensitive to paraquat than the wild type controls. This is in line with our finding that SOD‐1 is the major SOD in C. elegans . Since we have shown Mn to have an antioxidant‐like property, we examined the effect of Mn on paraquat toxicity. Mn supplementation (1 mM) in the culture medium increases resistance, as measured by LD50 by at least 3‐fold in sod‐1 mutant worms. Increased paraquat resistance is also observed in wild type worms treated with Mn; however, the extent of increase is only around 2‐fold. These results lend further support to the antioxidant potential of Mn. Funding provided by NIH.