The chronological life span is determined by measuring the survival time of populations of nondividing yeast. Alternatively, yeast life span is measured by monitoring the replicative potential of single mother cells. Each system has led to the identification of genes involved in either chronological or replicative aging (Bitterman et al., 2003). The activity of the products of some of these genes (SCH9, CYR1; see The Genetics of Chronological Aging: Yeast Methuselah Genes) consistently affects both replicative and chronological life span (Fabrizio et al., 2004b). Conversely, some genes encoding for stress resistance proteins (MSN2, SOD1/2) promote chronological longevity but negatively affect replicative life span, suggesting that there is only a partial overlap between the mechanisms that regulate replicative potential and survival of postmitotic yeast (Fabrizio et al., 2004b). In the following section we review both paradigms with emphasis on the chronological life span.
Was this article helpful?