Induction of lacI- mutations in Escherichia coli cells after single and split-dose irradiation.
In the lacI system of Escherichia coli, X-ray mutagenesis follows a linear-quadratic curve with suppression; the survival curve is exponential. Dose fractionation leads to nearly complete repair of premutational lesions during an incubation interval of 3.5 h. Repair starts with a delay of 1.5-2 h, suggesting the involvement of an inducible repair/mutation fixation system. The dose-dependence of mutagenesis is described by a simple model assuming two hits being required. A probable explanation might be that the premutagenic lesions consist of two closely spaced lesions on the opposite strands of the DNA molecule.
Institute of Biophysics, Brno, CSFR.
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S
Kozubek
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L
Ryznar
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G
Horneck
D004307:Dose-Response Relationship, Radiation; D004926:Escherichia coli / Q000235:genetics / Q000528:radiation effects*; D009154:Mutation; D011829:Radiation Dosage; D011831:Radiation Genetics