In 1988 geneticist Tom Johnson of the University of Colorado announced the discovery of a mutant gene in C. elegans that at 25ºC increased mean life span 65% and maximum lifespan 110%. Johnson named the gene age−1 in the expectation that other genes for aging would be found. Caloric Restriction with Adequate Nutrition (CRAN) further extends the lifespan of age−1 mutants. age−1 mutants were shown to have elevated Cu/Zn SOD and CAT (nematodes, unlike vertebrates, do not have glutathione peroxidase). age−1 mutants show a lower rate of deletions in the mitochondrial genome than wild-types. C. elegans homozygous for nonsense age−1 gene mutations have shown a ten-fold increase in maximum lifespan.