Aging and stress: The role of the environment in cellular replication

In single cell organisms, such as yeast and bacteria, cells age as they divide – a clock where time is counted by consecutive cell division events. Aging is characterized by a decrease in replicative fitness, which correlates with the increased probability of death. Although both in prokaryotes and eukaryotes asymmetries at cell division define the identity of the aging cell, setting the temporal and causative order of aging events, an important question has remained unsolved: how does the environment influence aging? It has been reported that under favourable conditions, cells avoid aging or age slowly, while under stress, aging is triggered or accelerated. Stress-induced changes in division morphology or damage segregation might modulate the rate of aging. This article explores the connection between aging and stress in unicellular organisms, highlighting evolutionarily conserved features.