ИСТИНА

Сlonal populations of yeast cells show significant individual cell heterogeneity. This is a result of stochastic processes (e.g. molecular noise) amplified by a positive feedback loops or a consequence of cell division asymmetry. 15-20 consequent rounds of asymmetrical cell division in yeast Saccharomyces cerevisiae lead to the dysfunction and death of the mother cells (so called replicative aging). However, a clonal population of proliferating cells is mainly represented by young cells due to constant dilution of the old cells by the newborn ones. Therefore, even a mild early manifestations of replicative aging can have a significant impact on the integral performance of yeast population. We found that a change in mitochondrial network morphology and a decrease in mitochondrial isocitrate dehydrogenases levels happen very early during the course of replicative aging in S.cerevisiae. While the young yeast mother cells were found to be more stress-resistant than the daughter cells, the resistance started to decline after the generation of 3-4 daughter cells. We suggest that the early manifestations of replicative aging induce adaptive responses which provide stress-resistance phenotype for the young mother cells. If so, early manifestations of replicative aging appear to be a bet-hedging mechanism which ensures the survival under the randomly changing environmental conditions.