Hays J B, Boehmer S
Proc Natl Acad Sci U S A. 1978 Sep;75(9):4125-9. doi: 10.1073/pnas.75.9.4125.
Intracellular lambda DNA (from EDTA-sensitive tandem duplication phages) was extracted from infected rec+ bacteria and scored for infectivity and recombination (loss of duplication) by transfection of recA recB spheroplasts and subsequent assay for EDTA resistance. When phage development was blocked by repressor or by antibiotics (chloramphenicol and/or rifampin), the apparent recombination frequency was about 0.1% above the background value for recA infections. Prior irradiation of the phage greatly stimulated recombination; the frequency was 20% when UV fluence was 140 J/m2. Repair (recovery of infectivity) and recombination of irradiated phage DNA proceeded readily in the presence of chloramphenicol and rifampin. Inhibitors of DNA gyrase (coumermycin and oxolinic acid) blocked repair and reduced recombination. UV-stimulated recombination was very low in recA but nearly normal in recB cells: repair was reduced in both mutant strains. The recombination remained high as phage/cell ratios less than unity.
从感染的rec⁺细菌中提取细胞内λDNA（来自对EDTA敏感的串联重复噬菌体），通过转染recA recB原生质球并随后检测EDTA抗性来评估其感染性和重组（重复丢失）情况。当噬菌体发育被阻遏物或抗生素（氯霉素和/或利福平）阻断时，recA感染的表观重组频率比背景值高约0.1%。噬菌体预先照射极大地刺激了重组；当紫外线通量为140 J/m²时，重组频率为20%。在氯霉素和利福平存在的情况下，受照射噬菌体DNA的修复（感染性恢复）和重组很容易进行。DNA回旋酶抑制剂（香豆霉素和氧氟沙星）阻断修复并降低重组。紫外线刺激的重组在recA细胞中非常低，但在recB细胞中接近正常：两种突变菌株中的修复都减少。当噬菌体/细胞比率小于1时，重组仍然很高。
