Zadrag Renata, Bartosz Grzegorz, Bilinski Tomasz
Department of Biochemistry and Cell Biology, University of Rzeszów, Rzeszów, Poland.
Curr Aging Sci. 2008 Dec;1(3):159-65. doi: 10.2174/1874609810801030159.
The applicability of the free radical theory of aging to the yeast S. cerevisiae is a matter of debate. In order to get an insight into this question, we studied the reproductive potential (the number of buds produced), reproductive lifespan (the time during which a yeast cell is able to divide), postreproductive lifespan (duration of life of yeast cells which ceased to divide) and total lifespan (sum of reproductive lifespan and postreproductive lifespan) of three isogenic pairs of yeast strains. Each pair contained a parent strain and a disruptant of gene(s) coding for important antioxidant enzyme(s) (CuZn-superoxide dismutase, all five peroxiredoxins or glutaredoxin 5). Although the reproductive potential was decreased in all antioxidant enzyme-deficient mutants, the differences in the reproductive lifespan between the parent strains and the mutants were less pronounced while postreproductive lifespan and total lifespan were not diminished in the mutants. These results suggest that either the free-radical theory of aging is not applicable to S. cerevisiae or that this yeast is not a proper model organism for the study of aging of higher organisms. In our opinion the latter possibility is more apparent and the increase in cell volume (unavoidable for a cell propagating by budding) rather than accumulation of oxidative damage may be the main reason for the cessation of budding (and perhaps postreproductive death) in S. cerevisiae.
衰老的自由基理论对酿酒酵母的适用性存在争议。为了深入了解这个问题，我们研究了三对同基因酵母菌株的繁殖潜力（产生的芽的数量）、繁殖寿命（酵母细胞能够分裂的时间）、繁殖后寿命（停止分裂的酵母细胞的寿命时长）和总寿命（繁殖寿命与繁殖后寿命之和）。每对菌株都包含一个亲本菌株和一个编码重要抗氧化酶（铜锌超氧化物歧化酶、所有五种过氧化物酶或谷氧还蛋白5）的基因缺失突变体。尽管所有抗氧化酶缺陷型突变体的繁殖潜力都有所降低，但亲本菌株与突变体之间繁殖寿命的差异并不明显，而突变体的繁殖后寿命和总寿命并未缩短。这些结果表明，要么衰老的自由基理论不适用于酿酒酵母，要么这种酵母不是研究高等生物衰老的合适模式生物。我们认为后一种可能性更明显，细胞体积的增加（通过出芽繁殖的细胞不可避免）而非氧化损伤的积累可能是酿酒酵母停止出芽（也许还有繁殖后死亡）的主要原因。
