The genetics of aging in the yeast Saccharomyces cerevisiae.

The yeast Saccharomyces cerevisiae possesses a finite life span similar in many attributes and implications to that of higher eukaryotes. Here, the measure of the life span is the number of generations or divisions the yeast cell has undergone. The yeast cell is the organism, simplifying many aspects of aging research. Most importantly, the genetics of yeast is highly-developed and readily applicable to the dissection of longevity. Two candidate longevity genes have already been identified and are being characterized. Others will follow through the utilization of both the primary phenotype and the secondary phenotypes associated with aging in yeast. An ontogenetic theory of longevity that follows from the evolutionary biology of aging is put forward in this article. This theory has at its foundation the asymmetric reproduction of 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 more characteristic of somatic cell division, tumor cells of somatic origin will not be totipotent, and organisms that reproduce symmetrically will not have intrinsic limits to their longevity.