Characterization of a life-extending mutation in age-2, a new aging gene in Caenorhabditis elegans

We have generated a life-extending mutation, yw23, in Caenorhabditis elegans. The mutation is in what appears to be a new aging gene, which we have designated age-2. When homozygous, yw23 produces an increase of mean and maximum life span of about 20% over that of the wild-type strain, N2. Strain HG23 [age-2(yw23)] was obtained by screening for longer life spans among 430 lines of nematodes two generations after exposure to the mutagen ethylmethanesulfonate. Strain HG231 [age-2(yw23)] was obtained after a single out-crossing of HG23 to N2. When compared with N2, HG231 exhibits normal motility, slightly higher swimming rates, reduced fertility (especially at higher temperatures), somewhat longer development times, and a slightly larger size at the time of first egg laying. A Gompertz analysis suggests that HG231 extends life span by reducing the initial mortality rate. In genetic crosses, yw23 complements other known aging mutants in C. elegans genes-age-1, daf-2, spe-26, clk-1, clk-2, clk-3, and gro-1. A double-mutant strain, HG284, combining mutations in age-1 and age-2, lives longer than animals with individual mutations in either age-1 or age-2, and exhibits a longer life span at 25 degrees C than at 20 degrees C.