Relative rates of repair of single-strand breaks and postirradiation DNA degradation in normal and induced cells of Escherichia coli

Pollard, Ernest C.; Fugate, J.K.

doi:10.1016/s0006-3495(78)85393-4

Cited by 10 publications

(3 citation statements)

References 16 publications

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“…It is well known that treatment of cells with one DNA damaging agent, followed by incubation in growth conditions, makes them better prepared to repair DNA lesions from subsequent exposures to different DNA damaging treatments (216, 255). This inducible response to DNA damage, called the SOS response by Miroslav Radman (262), is best demonstrated by the effect of split-dose DNA damaging treatments, during which repair-proficient cells show better survival after a particular dose of DNA damaging treatment if the treatment is delivered in several sub-doses separated by short time intervals (77, 277).…”

Section: Evolution Versus Survivalmentioning

confidence: 99%

Homologous Recombination—Experimental Systems, Analysis, and Significance

Kuzminov

2011

EcoSal Plus

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Homologous recombination is the most complex of all recombination events that shape genomes and produce material for evolution. Homologous recombination events are exchanges between DNA molecules in the lengthy regions of shared identity, catalyzed by a group of dedicated enzymes. There is a variety of experimental systems in E. coli and Salmonella to detect homologous recombination events of several different kinds. Genetic analysis of homologous recombination reveals three separate phases of this process: pre-synapsis (the early phase), synapsis (homologous strand exchange) and post-synapsis (the late phase). In E. coli, there are at least two independent pathway of the early phase and at least two independent pathways of the late phase. All this complexity is incongruent with the originally ascribed role of homologous recombination as accelerator of genome evolution: there is simply not enough duplication and repetition in enterobacterial genomes for homologous recombination to have a detectable evolutionary role, and therefore not enough selection to maintain such a complexity. At the same time, the mechanisms of homologous recombination are uniquely suited for repair of complex DNA lesions called chromosomal lesions. In fact, the two major classes of chromosomal lesions are recognized and processed by the two individual pathways at the early phase of homologous recombination. It follows, therefore, that homologous recombination events are occasional reflections of the continual recombinational repair, made possible in cases of natural or artificial genome redundancy.

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Section: Evolution Versus Survivalmentioning

confidence: 99%

Homologous Recombination—Experimental Systems, Analysis, and Significance

Kuzminov

2011

EcoSal Plus

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“…a1 (1978) reported the equivalent repair ability in E. coli B,, and B,-, using a D N A unwinding technique. Pollard and Fugate (1978) also reported that E. coli B$-, is able to repair SSB. It is interesting to note that our result on 5, for E. coli B,-, and B,, is close to the experimental one by Ahnstrom et al Town e?…”

Section: Resultsmentioning

confidence: 95%

Laser line selection in an electric-discharge CO laser

Avtonomov¹,

Zavertyaev²,

Kochetkov³

et al. 1978

Sov. J. Quantum Electron.

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A new model is applied to bacteria exposed to tritiated water. In this model, the relation between the radiation quality, induction of single-and double-strand breaks in DNA and their repair in vivo can be reasonably described in terms of the microdosimetric distribution and the modification factors for single-and double-strand breaks in DNA.First, a mathematical formulation of R B E of tritium p rays relative to an arbitrary reference radiation for killing effect on bacteria is derived on this model. Typical theoretical results on the survival curve parameters for bacteria exposed to tritiated water and R B E of tritium p rays relative to 6oCo y rays are presented. I t is found that R B E of tritium p rays depends on the ability of the cell to repair DNA damage. The present model is applied to the survival of Escherichia coli B , -, exposed to tritiated water and 7 MeV electrons. Although the average L E T of tritium p rays is remarkably higher than that of 7 MeV electrons, the experimental result that R B E of tritium p rays relative to 7 MeV electrons is close to unity, is reasonably explained by the present model.

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Section: The Large Value Of ( U ~) ~/ ( ~T ~) ~~mentioning

confidence: 95%

Theory of relative biological effectiveness (RBE) of tritium β rays: bacteria killing effects of tritiated water

Iwanami¹,

Oda²

1987

Phys. Med. Biol.

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A new model is applied to bacteria exposed to tritiated water. In this model, the relation between the radiation quality, induction of single- and double-strand breaks in DNA and their repair in vivo can be reasonably described in terms of the microdosimetric distribution and the modification factors for single- and double-strand breaks in DNA. First, a mathematical formulation of RBE of tritium beta rays relative to an arbitrary reference radiation for killing effect on bacteria is derived on this model. Typical theoretical results on the survival curve parameters for bacteria exposed to tritiated water and RBE of tritium beta rays relative to 60Co gamma rays are presented. It is found that RBE of tritium beta rays depends on the ability of the cell to repair DNA damage. The present model is applied to the survival of Escherichia coli Bs-1 exposed to tritiated water and 7 MeV electrons. Although the average LET of tritium beta rays is remarkably higher than that of 7 MeV electrons, the experimental result that RBE of tritium beta rays relative to 7 MeV electrons is close to unity, is reasonably explained by the present model.

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Relative rates of repair of single-strand breaks and postirradiation DNA degradation in normal and induced cells of Escherichia coli

Cited by 10 publications

References 16 publications

Homologous Recombination—Experimental Systems, Analysis, and Significance

Homologous Recombination—Experimental Systems, Analysis, and Significance

Laser line selection in an electric-discharge CO laser

Theory of relative biological effectiveness (RBE) of tritium β rays: bacteria killing effects of tritiated water

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