MacLean M, Harris N, Piper P W
Department of Biochemistry and Molecular Biology, University College London, Gower Street, London WC1E 6BT, UK.
Yeast. 2001 Apr;18(6):499-509. doi: 10.1002/yea.701.
Budding yeast can be considered to have two distinct lifespans: (a) a replicative (budding, non-chronological) lifespan, measured as the number of daughters produced by each actively dividing mother cell; and (ii) a chronological lifespan, measured as the ability of stationary cultures to maintain viability over time. In non-dividing cells, essential components that become damaged cannot be diluted out through cell division but must, of necessity, be turned over and renewed. By elevating stress resistances, many of the activities needed for such renewal should be elevated with commensurate reduction in the steady-state levels of damaged cell components. Therefore, chronological lifespan in particular might be expected to relate to stress resistance. For yeast to attain a full chronological lifespan requires the expression of the general stress response. It is more important, though, that the cells should be efficiently adapted to respiratory maintenance, since it is cultures grown to stationary phase on respiratory media that usually display the longest chronological lifespans. For this reason, respiration-adapted cells potentially provide a better model of chronological ageing than cultures pre-grown on glucose.
(a) 复制性（出芽，非时间顺序）寿命，以每个活跃分裂的母细胞产生的子细胞数量来衡量；以及 (ii) 时间顺序寿命，以静止培养物随时间维持活力的能力来衡量。在不分裂的细胞中，受损的必需成分无法通过细胞分裂被稀释掉，而必然需要更新和替换。通过提高抗逆性，这种更新所需的许多活动应该会增加，同时受损细胞成分的稳态水平会相应降低。因此，尤其可以预期时间顺序寿命与抗逆性有关。酵母要达到完整的时间顺序寿命需要一般应激反应的表达。不过，更重要的是细胞应能有效地适应呼吸维持，因为在呼吸培养基上生长至静止期的培养物通常显示出最长的时间顺序寿命。出于这个原因，与在葡萄糖上预培养的培养物相比，适应呼吸的细胞可能为时间顺序衰老提供更好的模型。
