The RAS genes: a homeostatic device in Saccharomyces cerevisiae longevity

The genetic analysis of the yeast replicative life span has revealed the im portance of metabolic control and resistance to stress. It has also illumin ated the pivotal role in determining longevity that the RAS genes play by t he maintenance of homeostasis. This role appears to be performed by the coo rdination of a variety of cellular processes. Metabolic control seems to oc cupy a central position among these cellular processes that include stress resistance. Some of the features of metabolic control in yeast resemble the effects of the daf pathway for adult longevity in Caenorhabditis elegans a nd the metabolic consequences of selection for extended longevity in Drosop hila melanogaster, as well as some of the features of caloric restriction i n mammals. The distinction between dividing and nondividing cells is propos ed to be less important for the aging process than generally believed becau se these cell types are part of a metabolic continuum in which the total me tabolic capacity determines life span. As a consequence, the study of yeast aging may be helpful in understanding processes occurring in the aging bra in. (C) 1999 Elsevier Science Inc. All rights reserved.