Summary
Strains of Escherichia coli K-12 and B/r made by transduction of the exrA allele from a Bs-2 derivative have been compared with Exr(W)− strains derived from Bs-1 and Bs-2 by mutation (E.M. Witkin, 1967). Both transduced exrA and Exr(W)− strains were almost unmutable by gamma radiation, but the former class were as sensitive to gamma radiation as recA strains and, like them, were unable to repair single-strand DNA breaks as detected by the McGrath-Williams technique. In contrast the Exr(W)−strains were as resistant to gammaradiation as Exr(W)+ strains derived from them and were equally efficient in repairing single-strand breaks. The existence of Exr(W)−strains suggests that the mutagenicity of single-strand breaks may depend entirely on the way in which they are repaired. The properties of the (Exr(W)−strains cannot be ascribed solely to the transducable exrA allele.
A large effect of diffuse daylight in lowering the molecular weight of DNA on alkaline sucrose gradients is described which, unless prevented, may lead to erroneous results in such experiments.
This is a preview of subscription content, log in via an institution to check access.
Similar content being viewed by others
References
Boyle, J. M., Symonds, N.: Radiation sensitive mutants of T4D.1. T4y: A new radiation sensitive mutant; effect of the mutation on radiation survival, growth and recombination. Mutation Res. 8, 431–439 (1969).
Bridges, B. A.: Simple bacterial systems for detecting mutagenic agents. Lab. Pract. 21, 413–419 (1972).
Bridges, B. A., Ashwood-Smith, M. J., Munson, R. J.: Correlation of bacterial sensitivities to ionizing radiation and mild heating. J. gen. Microbiol. 58, 115–124 (1969).
Bridges, B. A., Law, J., Munson, R. J.: Mutagenesis in Escherichia coli. II Evidence for a common pathway for mutagenesis by ultraviolet light, ionizing radiation and thymine deprivation. Molec. gen. Genet. 103, 266–273 (1968).
Bridges, B. A., Mottershead, R. P.: Gamma ray mutagenesis in a strain of Escherichia coli deficient in DNA polymerase I. Heredity, in the press (1972).
Bridges, B. A., Mottershead, R. P., Rothwell, M. A., Green, M. H. L.: Repair-deficient bacterial strains suitable for mutagenicity screening: tests with the fungicide captan. Chem. Biol. Interactions 5, 77–84 (1972).
Carrier, W. L., Setlow, R. B.: Paper strip method for assaying gradient fractions containing radioactive macromolecules. Analyt. Biochem. 43, 427–432 (1971).
Davis, B. D., Mingioli, E. S.: Mutants of Escherichia coli requiring methionine or vitamin B12. J. Bact. 60, 17–28 (1950).
Donch, J., Chung, Y. S., Greenberg, J.: Locus for radiation resistance in Escherichia coli strain B/r. Genetics 61, 363–370 (1969).
Donch, J., Greenberg, J.: Loci of radiation sensitivity in Bs strains of Escherichia coli. Genet. Res. (Camb.) 11, 183–191 (1968).
Elkind, M. M.: Sedimentation of DNA released from Chinese hamster cells. Biophys. J. 11, 502–520 (1971).
Green, M. H. L., Rothwell, M. A., Bridges, B. A.: Mutation to prototrophy in Escherichia coli K-12: effect of broth on UV-induced mutation in strain AB1157 and four excisiondeficient mutants. Mutation Res. 16, 225–234 (1972).
Greenberg, J.: A locus for radiation sensitivity in Escherichia coli Bs-2. Genetics 50, 639–648 (1964).
Greenberg, J.: Loci for radiation sensitivity in Escherichia coli strain Bs-1. Genetics 55, 193–201 (1967).
Hill, R. F., Simson, E.: A study of radiosensitive and radioresistant mutants of Escherichia coli strain B. J. gen. Microbiol. 35, 105–114 (1961).
Howard-Flanders, P., Boyce, R. P., Theriot, L.: Three loci in Escherichia coli K-12 that control the excision of pyrimidine dimers and certain other mutagen products from DNA. Genetics 53, 1119–1136 (1966).
Howard-Flanders, P., Theriot, L.: Mutants of Escherichia coli K-12 defective in DNA repair and in genetic recombination. Genetics 53, 1137–1150 (1966).
Kapp, D. S., Smith, K. C.: Repair of radiation-induced damage in Escherichia coli. II Effect of rec and uvr mutations on radiosensitivity, and repair of X-ray induced single-strand breaks in deoxyribonucleic acid. J. Bact. 103, 49–54 (1970).
Kondo, S.: Mutagenicity versus radiosensitivity in Escherichia coli. Proc. 12th Intern. Congr. Genetics 2, 126–127 (1968).
Mattern, I. E., Zwenk, H., Rörsch, A.: The genetic constitution of the radiation sensitive mutant Escherichia coli Bs-1 Mutation Res. 3, 374–380 (1966).
McGrath, R. A., Williams, R. W.: Reconstruction in vivo of irradiated Escherichia coli deoxyribonucleic acid; the rejoining of broken pieces. Nature (Lond.) 212, 534–535 (1966).
Miura, A., Tomizawa, J.: Studies on radiation-sensitive mutants of E. coli, III. Participation of the Rec system in induction of mutation by ultra-violet irradiation. Molec. gen. Genet. 103, 1–10 (1968).
Town, C. D., Smith, K. C., Kaplan, H. C.: DNA polymerase required for the rapid rejoining of X-ray induced DNA strand breaks in vivo. Science 172, 851–853 (1971).
Witkin, E. M.: Mutation-proof and mutation prone modes of survival in derivatives of Escherichia coli B differing in sensitivity to ultraviolet light. Brookhaven Symp. Biol. 20, 17–55 (1967).
Author information
Authors and Affiliations
Additional information
Communicated by E. M. Witkin
Rights and permissions
About this article
Cite this article
Sedgwick, S.G., Bridges, B.A. Survival, mutation and capacity to repair single-strand DNA breaks after gamma irradiation in different Exr− strains of Escherichia coli . Molec. Gen. Genet. 119, 93–102 (1972). https://doi.org/10.1007/BF00269129
Received:
Published:
Issue Date:
DOI: https://doi.org/10.1007/BF00269129