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Chemical Protection against Single-Strand Breaks in DNA of Gamma-Irradiated E. coli

D. M. Ginsberg and H. K. Webster
Radiation Research
Vol. 39, No. 2 (Aug., 1969), pp. 421-435
DOI: 10.2307/3572678
Stable URL: http://www.jstor.org/stable/3572678
Page Count: 15
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Chemical Protection against Single-Strand Breaks in DNA of Gamma-Irradiated E. coli
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Abstract

The effects of a chemical radioprotectant, beta-mercaptoethylamine (MEA), on gamma-induced single-strand breaks in DNA from three strains (B/r, ${\rm B}_{{\rm s}-1}$, and 15TAU-bar) of Escherichia coli have been studied. The amount of DNA single-strand breakage in irradiated cultures was similar in all three strains. Although MEA enhanced radiation survival in both logarithmic- and stationary-phase cultures, it protected against DNA strand breakage only in the stationary-phase cultures. Single-strand breakage of DNA could not be correlated with radiation killing, even in the very radiosensitive strain ${\rm B}_{{\rm s}-1}$. The effects of MEA on DNA strand breakage and killing in cultures of strain 15TAU-bar starved of amino acids with and without methionine provided further evidence that single-strand breaks in DNA are not significant lesions in gamma-ray killing of bacteria.

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