The budding yeast, Saccharomyces cerevisiae, as a model for aging research: a critical review

In this review we discuss the yeast as a paradigm for the study of aging. T he budding yeast Saccharomyces cerevisiae, which can proliferate in both ha ploid and diploid states, has been used extensively in aging research. The budding yeast divides asymmetrically to form a 'mother' cell and a bud. Two major approaches, 'budding life span' and 'stationary phase' have been use d to determine 'senescence' and 'life span' in yeast. Discrepancies observe d in metabolic behavior and longevity between cells studied by these two sy stems raise questions of how 'life span' in yeast is defined and measured. Added to this variability in experimental approach and results is the varie ty of yeast strains with different genetic make up used as 'wild type' and experimental organisms. Another problematic genetic point in the published studies on yeast is the use of both diploid and haploid strains. We discuss the inherent, advantageous attributes that make the yeast an attractive ch oice for modern biological research as well as certain pitfalls in the choi ce of this model for the study of aging. The significance of the purported roles of the Sir2 gene, histone deacetylases, gene silencing, rDNA circles and stress genes in determination of yeast 'life span' and aging is evaluat ed. The relationship between cultivation conditions and longevity are asses sed. Discrepancies between the yeast and mammalian systems with regard to a ging are pointed out. We discuss unresolved problems concerning the suitabi lity of the budding yeast for the study of basic aging phenomena. (C) 2000 Elsevier Science Ireland Ltd. All rights reserved.