AGING MECHANISMS IN FRUIT-FLIES

Genetic analysis of Drosophila has provided evidence in support of two proposed evolutionary genetic mechanisms of aging: mutation accumulat ion and antagonistic pleiotropy. Both mechanisms result from the lack of natural selection acting on old organisms. Analyses of large number s of flies have revealed that mortality rates do not continue to rise with age as previously thought, but plateau at advanced ages. This phe nomenon has implications both for models and for definitions of aging, and may be explained by the evolutionary theories. The physiological processes and genes most relevant to aging are being identified using Drosophila lines selected in the laboratory for postponed senescence. Oxidative stress and insufficient metabolic reserves/capacity may be p articularly important factors in limiting the fruitfly lifespan. Genes which exhibit aging-related changes in expression are now being ident ified. Transgenic flies are being used to analyze the mechanisms of su ch aging-related gene expression, and to test the effects of specific genes on aging and aging-related deterioration.