Bertram H, Hagen U
GSF-Forschungszentrum, Institut für Strahlenbiologie, Neuherberg, Germany.
Int J Radiat Biol. 1992 Jul;62(1):3-8. doi: 10.1080/09553009214551771.
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 In most of the base substitutions a pre-existing base pair had been replaced by an A/T pair; this might come from 'non-instructional sites' like abasic sites.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.
通过60Co-γ辐射诱导溶解的λ噬菌体DNA中λ阻遏物基因cI（710 bp）发生突变。经体外DNA包装成λ噬菌体颗粒（包装噬菌体）并使突变体表型表达后，直接对DNA进行测序。三分之二的突变位于基因的氨基末端区域，未发现任何热点迹象。变化包括（+1）插入（25%）和碱基替换（75%）。转换均为G/C到A/T。颠换大多为G/C到C/G，少数为G/C到T/A。未发现A/T到T/A颠换、A/T到G/C转换、缺失和大片段重排。在大多数碱基替换中，一个预先存在的碱基对被A/T对取代；这可能来自无碱基位点等“非指令性位点”。文中考虑了几种碱基替换的机制。
