A Study of Radiosensitive and Radioresistant Mutants of Escherichia coli strain B

Hill, Reba M.; Simson, Eva

doi:10.1099/00221287-24-1-1

Cited by 126 publications

(40 citation statements)

References 19 publications

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“…The number is known to be correlated with the number of cytologically observable nuclear bodies per cell (Fuerst and Stent 1957;Koch 1967). Taking into account the fact that some strains of E. coli are more sensitive to 32P decay as well as to u. v. than their parent strains (Hill and Simson 1961), it may be supposed that the lesion caused by 32P decay differs from the u. v. induced lesion in the mode of the repair and/or the expression of its lethality.…”

Section: Discussionmentioning

confidence: 99%

EFFECTS OF GROWTH CONDITIONS ON SENSITIVITY OF ESCHERICHIA COLI TO INACTIVATION BY ULTRAVIOLET AND 32P DECAY

Yan

1969

The Japanese journal of genetics

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Section: Discussionmentioning

confidence: 99%

EFFECTS OF GROWTH CONDITIONS ON SENSITIVITY OF ESCHERICHIA COLI TO INACTIVATION BY ULTRAVIOLET AND 32P DECAY

Yan

1969

The Japanese journal of genetics

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“…dose and for photoreactivation (p.r. ), has been described previously (Hill & Simson, 1961;Hill, 1965). In the present experiments, white light from the G.E.…”

Section: Methodsmentioning

confidence: 99%

Modification of Lethality and Mutagenesis by Growth Inhibition of Ultraviolet-irradiated Escherichia coli strain B/R

Hill

1968

Journal of General Microbiology

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-irradiated in the lag and logarithmic phases of the growth cycle. Without post-irradiation growth inhibition, survival and yields of mutants were higher for logarithmic phase cells. Post-irradiation growth inhibition reduced yields of mutants from both types of cells to similar extents and markedly increased the survival of logarithmic phase cells, both after small and large U.V. doses. In the case of lag phase cells, a survival increase mediated by post-irradiation growth inhibition, could only be observed by giving a large U.V. dose or by inhibiting repair of damage occurring after plating for colony formation. Post-irradiation growth inhibition was observed to have two effects-one tending to increase survival and another tending to enhance lethality. The results indicate that observable effects of postirradiation growth inhibition on survival and induced mutation in E. coli B/R and whether or not such effects are correlated depend upon a number of factors. These include : (I) relative amounts of repair occurring during growth inhibition and during subsequent growth; (2) heterogeneity of the population with respect to growth phase, intrinsic repair ability and amount of damage; and (3) relative contributions of increased repair and increased killing-both mediated by post-irradiation growth inhibition.

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“…In both examples, the maximum endonuclease activity reactive towards x-irradiated DNA is obtained by the addition of 7-10 /Ag of protein to the reaction mixture. Furthermore, extracts prepared from the radiosensitive strain of E. coli, Bo1,, (15) demonstrated. Exposure of calf thymus DNA to 27 krads x-rays, the highest dose tested, resulted in greater than 80% inhibition of the endonuclease activity toward the x-irradiated RF-DNA.…”

Section: Methodsmentioning

confidence: 99%

Endonucleolytic incision of x-irradiated deoxyribonucleic acid by extracts of Escherichia coli.

Strniste¹,

Wallace²

1975

Proc. Natl. Acad. Sci. U.S.A.

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An endonuclease activity that reacts with x-irradiated DNA is present in extracts of E. coli. By using centrifugal methods to monitor the conversion of the supercoiled, circular double-stranded DNA for phage OX-174 (replicative form) or PM2 to the relaxed circular form it was possible to quantitate the rate of radiation induced endonuclease-sensitive sites in the DNA. For every single-strand break induced by x-rays under aerobic irradiation conditions, there is approximately one induced site sensitive to this endonuclease activity. Under irradiation conditions (addition of potassium iodide) that dramatically reduce rates of single-strand breaks and "alkalilabile" lesions, the number of endonuclease-sensitive sites relative to single-strand breaks increases approximately 4-fold. This nuclease is present in several strains of E. coli B and K12, including mutants deficient in DNA polymerase I, recombination gene products (rec mutants), ultraviolet light incision enzyme (uvrA mutant), and endonuclease II. It is suggested that this endonuclease may be involved in an excision repair process for damages incurred in DNA by ionizing radiation.It has been apparent for a number of years that bacteria repair damages induced by ionizing radiation. Most of the evidence for this has been genetic; that is, mutant strains of bacteria have been isolated which apparently lack repair systems.The most readily detectable lesions produced by ionizing radiation are strand breaks. Single-strand breaks can be physically reconstituted in Escherichia coli B/r but not in radiosensitive B,-, (1) or recA (2) mutants. DNA polymerase I has been shown to be involved in a rapid repair system of single-strand breaks (3) as well as in x-ray stimulated repair synthesis in toluene-treated Bacillis subtilis cells (4). A slower recombinational repair of single-strand breaks is dependent upon the recA gene product (3). Polynucleotide ligase under certain in vitro conditions has been shown to seal single-strand breaks induced by x-rays (5) and has been indirectly implicated in repair synthesis in the B. subtilis toluenized cell system (4).Comparisons between physical studies on strand breakage and bacteriophage lethality (6-9) have led to the hypothesis that damages other than strand breakage, such as base and sugar damages, contribute to lethality induced by ionizing radiation. Hariharan and Cerutti have described a radiolysis product of thymine which appears in the acid-soluble fraction during post-irradiation incubation of M1icrococcus radiodurans (10), thus indicating a possible excision-type repair mechanism for base damages. Also, extracts of .If. luteus exhibit endoAbbreviations: UV, ultraviolet; RF, replicative form. * Present address: Cellular and Molecular Radiobiology Group, H-9, Los Alamos Scientific Laboratory, Los Alamos, N.MA. 87544. 1997 nuclease activity for DNA irradiated in vivo (11) or in vitro (12) by y-rays. Recently Wilkins has shown that E. coli DNA y-irradiated in vivo possesses sites sensitive to the .If. luteus enz...

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A Study of Radiosensitive and Radioresistant Mutants of Escherichia coli strain B

Cited by 126 publications

References 19 publications

EFFECTS OF GROWTH CONDITIONS ON SENSITIVITY OF <i>ESCHERICHIA</i> <i>COLI</i> TO INACTIVATION BY ULTRAVIOLET AND <sup>32</sup>P DECAY

EFFECTS OF GROWTH CONDITIONS ON SENSITIVITY OF <i>ESCHERICHIA</i> <i>COLI</i> TO INACTIVATION BY ULTRAVIOLET AND <sup>32</sup>P DECAY

Modification of Lethality and Mutagenesis by Growth Inhibition of Ultraviolet-irradiated Escherichia coli strain B/R

Endonucleolytic incision of x-irradiated deoxyribonucleic acid by extracts of Escherichia coli.

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