Radical effects on mutation spectra in lambda phage.
Mutations in the lambda repressor gene cI (710 bp) were induced by 60Co-gamma radiation in dissolved lambda phage DNA. After in vitro DNA packaging to lambda phage particles (pack phage) and phenotypic expression of the mutants, DNA was sequenced directly. Two-thirds of mutations were located in the amino terminus region of the gene without any signs of hotspots. Changes consisted of (+1) insertions (25%) and base substitutions (75%). Transitions were exclusively G/C to A/T. Transversions were mostly G/C to C/G and few G/C to T/A. We did not find A/T to T/A transversions, A/T to G/C transitions, deletions and gross rearrangements. In most of the base substitutions a pre-existing base pair had been replaced by an A/T pair; this might come from 'non-instructional sites' like abasic sites. Several mechanisms for base substitutions are considered.
Bertram
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H
GSF-Forschungszentrum, Institut für Strahlenbiologie, Neuherberg, Germany.
Hagen
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U
D010582:Bacteriophage lambda / Q000528:radiation effects*; D001483:Base Sequence; D003037:Cobalt Radioisotopes; D004279:DNA, Viral / Q000528:radiation effects*; D005720:Gamma Rays; D008969:Molecular Sequence Data; D009154:Mutation
D003037:Cobalt Radioisotopes; D004279:DNA, Viral