THE GENETICS OF AGING IN THE YEAST SACCHAROMYCES-CEREVISIAE

The yeast Saccharomyces cerevisiae possesses a finite life span simila r in many attributes and implications to that of higher eukaryotes. He re, the measure of the life span is the number of generations or divis ions the yeast cell has undergone. The yeast cell is the organism, sim plifying many aspects of aging research. Most importantly, the genetic s of yeast is highly-developed and readily applicable to the dissectio n of longevity. Two candidate longevity genes have already been identi fied and are being characterized. Others will follow through the utili zation of both the primary phenotype and the secondary phenotypes asso ciated with aging in yeast. An ontogenetic theory of longevity that fo llows from the evolutionary biology of aging is put forward in this ar ticle. This theory has at its foundation the asymmetric reproduction o f cells and organisms, and it makes specific predictions regarding the genetics, molecular mechanisms, and phenotypic features of longevity and senescence, including these: GTP-binding proteins will frequently be involved in determining longevity, asymmetric cell division will be often encountered during embryogenesis while binary fission will be m ore characteristic of somatic cell division, tumor cells of somatic or igin will not be totipotent, and organisms that reproduce symmetricall y will not have intrinsic limits to their longevity.