Experimental evolution of aging in a bacterium

Ackermann, M. and Schauerte, A. and Stearns, S. C. and Jenal, U.. (2007) Experimental evolution of aging in a bacterium. BMC evolutionary biology, Vol. 7 , 126.

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Official URL: http://edoc.unibas.ch/dok/A5258537

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BACKGROUND: Aging refers to a decline in reproduction and survival with increasing age. According to evolutionary theory, aging evolves because selection late in life is weak and mutations exist whose deleterious effects manifest only late in life. Whether the assumptions behind this theory are fulfilled in all organisms, and whether all organisms age, has not been clear. We tested the generality of this theory by experimental evolution with Caulobacter crescentus, a bacterium whose asymmetric division allows mother and daughter to be distinguished. RESULTS: We evolved three populations for 2000 generations in the laboratory under conditions where selection was strong early in life, but very weak later in life. All populations evolved faster growth rates, mostly by decreasing the age at first division. Evolutionary changes in aging were inconsistent. The predominant response was the unexpected evolution of slower aging, revealing the limits of theoretical predictions if mutations have unanticipated phenotypic effects. However, we also observed the spread of a mutation causing earlier aging of mothers whose negative effect was reset in the daughters. CONCLUSION: Our results confirm that late-acting deleterious mutations do occur in bacteria and that they can invade populations when selection late in life is weak. They suggest that very few organisms – perhaps none- can avoid the accumulation of such mutations over evolutionary time, and thus that aging is probably a fundamental property of all cellular organisms.
Faculties and Departments:05 Faculty of Science > Departement Biozentrum > Infection Biology > Molecular Microbiology (Jenal)
05 Faculty of Science > Departement Biozentrum > Growth & Development > Molecular Microbiology (Jenal)
UniBasel Contributors:Jenal, Urs
Item Type:Article, refereed
Article Subtype:Research Article
Publisher:BioMed Central
Note:Publication type according to Uni Basel Research Database: Journal article
Last Modified:08 Nov 2012 16:13
Deposited On:22 Mar 2012 13:33

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