IsEscherichia coli getting old?

Woldringh, Conrad L.

doi:10.1002/bies.20271

Cited by 22 publications

(12 citation statements)

References 32 publications

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“…With symmetry and low damage, single-celled organisms are immortal (Figure 1A). Do high damage and asymmetry make them mortal [14], [19]–[22]? The model shows that it depends on the level of asymmetry and the rate of lifetime damage.…”

Section: Discussionmentioning

confidence: 99%

A Model for Damage Load and Its Implications for the Evolution of Bacterial Aging

Chao

2010

PLoS Genet

125

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Deleterious mutations appearing in a population increase in frequency until stopped by natural selection. The ensuing equilibrium creates a stable frequency of deleterious mutations or the mutational load. Here I develop the comparable concept of a damage load, which is caused by harmful non-heritable changes to the phenotype. A damage load also ensues when the increase of damage is opposed by selection. The presence of a damage load favors the evolution of asymmetrical transmission of damage by a mother to her daughters. The asymmetry is beneficial because it increases fitness variance, but it also leads to aging or senescence. A mathematical model based on microbes reveals that a cell lineage dividing symmetrically is immortal if lifetime damage rates do not exceed a threshold. The evolution of asymmetry allows the lineage to persist above the threshold, but the lineage becomes mortal. In microbes with low genomic mutation rates, it is likely that the damage load is much greater than the mutational load. In metazoans with higher genomic mutation rates, the damage and the mutational load could be of the same magnitude. A fit of the model to experimental data shows that Escherichia coli cells experience a damage rate that is below the threshold and are immortal under the conditions examined. The model estimates the asymmetry level of E. coli to be low but sufficient for persisting at higher damage rates. The model also predicts that increasing asymmetry results in diminishing fitness returns, which may explain why the bacterium has not evolved higher asymmetry.

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Section: Discussionmentioning

confidence: 99%

A Model for Damage Load and Its Implications for the Evolution of Bacterial Aging

Chao

2010

PLoS Genet

125

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“…Ribosomes and the most active DNA region near the origin all remain at the old pole during www.annualreviews.org • Individuality in Bacteria division. Accumulated damage in these molecules may contribute to cellular aging (19,87). However, old poles can still change shape and incorporate new components, so the hypothesis that they contribute to cellular aging is not substantiated and the mechanism and impacts of aging are not clear (87).…”

Section: Targeted Dna Rearrangementsmentioning

confidence: 99%

Individuality in Bacteria

2008

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While traditionally microbiologists have examined bacterial behavior averaged over large populations, increasingly we are becoming aware that bacterial populations can be composed of phenotypically diverse individuals generated by a variety of mechanisms. Though the results of different mechanisms, the phenomena of bistability, persistence, variation in chemotactic response, and phase and antigenic variation are all strategies to develop population-level diversity. The understanding of individuality in bacteria requires an appreciation of their environmental and ecological context, and thus evolutionary theory regarding adaptations to time-variable environments is becoming more applicable to these problems. In particular, the application of game and information theory to bacterial individuality has addressed some interesting problems of bacterial behavior. In this review we discuss the mechanisms of generating population-level variability, and the application of evolutionary theory to problems of individuality in bacteria.

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“…Recently, an old question-"Do bacteria age? "-was answered in the (mostly) affirmative (2,315,317,369). Older C. crescentus stalked cells produce progeny at reduced rates (2), and E. coli cells with older poles grow slightly more slowly than do cells with younger poles (317), though questions regarding the latter conclusion remain (369).…”

Section: Separationmentioning

confidence: 99%

The Selective Value of Bacterial Shape

Young

2006

Microbiol Mol Biol Rev

843

777

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SUMMARY Why do bacteria have shape? Is morphology valuable or just a trivial secondary characteristic? Why should bacteria have one shape instead of another? Three broad considerations suggest that bacterial shapes are not accidental but are biologically important: cells adopt uniform morphologies from among a wide variety of possibilities, some cells modify their shape as conditions demand, and morphology can be tracked through evolutionary lineages. All of these imply that shape is a selectable feature that aids survival. The aim of this review is to spell out the physical, environmental, and biological forces that favor different bacterial morphologies and which, therefore, contribute to natural selection. Specifically, cell shape is driven by eight general considerations: nutrient access, cell division and segregation, attachment to surfaces, passive dispersal, active motility, polar differentiation, the need to escape predators, and the advantages of cellular differentiation. Bacteria respond to these forces by performing a type of calculus, integrating over a number of environmental and behavioral factors to produce a size and shape that are optimal for the circumstances in which they live. Just as we are beginning to answer how bacteria create their shapes, it seems reasonable and essential that we expand our efforts to understand why they do so.

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IsEscherichia coli getting old?

Cited by 22 publications

References 32 publications

A Model for Damage Load and Its Implications for the Evolution of Bacterial Aging

A Model for Damage Load and Its Implications for the Evolution of Bacterial Aging

Individuality in Bacteria

The Selective Value of Bacterial Shape

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