Aging and Death in an Organism That Reproduces by Morphologically Symmetric Division

By E. Stewart, R. Madden, Grégory Paul, F. Taddei. PLoS Biology, 2005

669 citations recorded by the source corpus.

In macroscopic organisms, aging is often obvious; in single-celled organisms, where there is the greatest potential to identify the molecular mechanisms involved, identifying and quantifying aging is harder. The primary results in this area have come from organisms that share the traits of a visibly asymmetric division and an identifiable juvenile phase. As reproductive aging must require a differential distribution of aged and young components between parent and offspring, it has been postulated that organisms without these traits do not age, thus exhibiting functional immortality. Through automated time-lapse microscopy, we followed repeated cycles of reproduction by individual cells of the model organism Escherichia coli, which reproduces without a juvenile phase and with an apparently symmetric division. We show that the cell that inherits the old pole exhibits a diminished growth rate, decreased offspring production, and an increased incidence of death. We conclude that the two supposedly identical cells produced during cell division are functionally asymmetric; the old pole cell should be considered an aging parent repeatedly producing rejuvenated offspring. These results suggest that no life strategy is immune to the effects of aging, and therefore immortality may be either too costly or mechanistically impossible in natural organisms.

Subfields: Aging, Genetics, Molecular Biology

View Paper: https://www.semanticscholar.org/paper/1996c3774c759067a52fd786ede54565d8d69798

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Citations in the corpus

Life and death: metabolic rate, membrane composition, and life span of animals. (2007, background): “For a long time aging was believed to be restricted to multicellular animals; however, recently detailed measurements have shown it also to occur in the common bacteria Escherichia coli (340).”
Robust growth of Escherichia coli (2010, neutral): “coli [12] (see Experimental Procedures; Supplemental Movies S1A and S1B).”
Limit theorems for Markov processes indexed by continuous time Galton--Watson trees (2009, background): “Moreover experiments (Stewart et al. [ 50 ]) indicate that the transmission of this characteristic in the two daughter cells may be asymmetric.”
Limit theorems for bifurcating Markov chains. Application to the detection of cellular aging (2007, methodology): “performed in [22]: it focuses on the differences X2i −X2i+1 between sisters.”
High-throughput, subpixel-precision analysis of bacterial morphogenesis and intracellular spatio-temporal dynamics (2011, background): “Experiments of this type have already been proven useful in examining cellular senescence (Ackermann et al., 2003; Stewart et al., 2005; Wang et al., 2010a) and in uncovering cell-to-cell fluctuations in cellular components or gene expression within clonal populations (Locke and Elowitz, 2009).”
Measuring single-cell gene expression dynamics in bacteria using fluorescence time-lapse microscopy (2011, background): “Other slide preparation protocols have been developed in other laboratories 6,24 ; however, the overall concept is very similar.”
The Selective Value of Bacterial Shape (2006, background): “At division, one daughter cell would be virtually new, while the “older” daughter would carry away the spoiled material (315, 317).”
Statistical estimation of a growth-fragmentation model observed on a genealogical tree (2012, methodology): “lysis on E. coli data Finally, we analyse a dataset obtained through microscopic time-lapse imaging of single bacterial cells growing in rich medium, by Wang, Robert et al. [38] and by Stewart et al. [35]. Thanks to a micro uidic set-up, the experimental conditions are well controlled and stable, so”