INVERTEBRATE GERONTOLOGY - THE AGE MUTATIONS OF CAENORHABDITIS-ELEGANS

Ageing is a complex phenomenon which remains a major challenge to mode rn biology. Although the evolutionary biology of ageing is well unders tood, the mechanisms that limit lifespan are unknown. The isolation an d analysis of single-gene mutations which extend lifespan (Age mutatio ns) is likely to reveal processes which influence ageing. Caenorhabdit is elegans is the only metazoan in which Age mutations have been ident ified. The Age mutations not only prolong life, but also confer a comp lex array of other phenotypes. Some of these phenotypes provide clues to the evolutionary origins of these genes while others allude to mech anisms of lifespan-extension, Many of the Age genes interact and share a second common phenotype, that of stress resistance. Rather than inv ertebrate ageing being determined by a 'clock mechanism', a picture is emerging of ageing as a non-adaptive process determined, in part, by resistance to intrinsic stress mediated by stress-response genes.