title: DNA degradation in Escherichia coli 15T-L- induced by fast proton bombardment.
abstract: DNA degradation and its temperature dependence as a function of linear energy transfer were studied in Excherichia coli using fast proton irradiation as the initiating agent. The data indicate that radiation-induced DNA degradation can proceed by two processes. The first, or fast component, begins immediately after irradiation with (60)Co gamma-rays or with fast protons at doses less than 10(10) protons/cm(2). The rate is high and involves a maximum of about 50% degradation. It is elicited more efficiently by protons of high linear energy transfer. The second, or slow component, results from higher doses of fast proton bombardment. There is a delay between irradiation and the initiation of this slower component, but 100% of the DNA complement is degraded. The data indicate that both processes are enzyme-mediated, the first probably by normal DNA-related activity and the second by DNAase activity.
mesh_terms: D002247:Carbon Isotopes; D003036:Cobalt Isotopes; D004261:DNA Replication / Q000528:radiation effects; D004269:DNA, Bacterial / Q000528:radiation effects*; D003851:Deoxyribonucleases / Q000528:radiation effects; D004926:Escherichia coli / Q000528:radiation effects*; D007930:Leucine / Q000378:metabolism; D011522:Protons; D013941:Thymine / Q000378:metabolism
chemical_list: D002247:Carbon Isotopes; D003036:Cobalt Isotopes; D004269:DNA, Bacterial; D011522:Protons; D003851:Deoxyribonucleases; D007930:Leucine; D013941:Thymine