MacPhee D G, Hafner L M
Department of Microbiology, La Trobe University, Bundoora, Vic., Australia.
Mutat Res. 1988 Mar-Apr;207(3-4):99-105. doi: 10.1016/0165-7992(88)90071-1.
We have found that a temperature-sensitive mutation in the polA gene of Salmonella typhimurium strain LT2 causes precise excision of transposon Tn10 to occur at significantly increased frequencies in cells incubated at the restrictive temperature. In our experiments, precise excision from a site in the tryptophan operon was measured by determining the frequency of reversion of the auxotrophic trp1014::Tn10 polA7 strain to prototrophy on defined medium containing a trace amount of broth. Because the yields of revertants at 37 degrees C were of the order of 200 colonies per plate, it was possible to measure the effects of chemical inhibitors on the processes involved in precise excision. We now report that all of the DNA-repair inhibitors we have studied (caffeine, ethionine, acriflavine, procaine and cinnamaldehyde) are effective inhibitors of precise excision of Tn10, and can therefore be defined as antimutagens.
我们发现，鼠伤寒沙门氏菌LT2菌株的polA基因中的温度敏感突变会导致转座子Tn10在限制温度下培养的细胞中以显著增加的频率进行精确切除。在我们的实验中，通过测定营养缺陷型trp1014::Tn10 polA7菌株在含有微量肉汤的限定培养基上回复为原养型的频率，来测量从色氨酸操纵子中的一个位点进行的精确切除。由于在37摄氏度时回复子的产量约为每平板200个菌落，因此有可能测量化学抑制剂对精确切除过程的影响。我们现在报告，我们研究的所有DNA修复抑制剂（咖啡因、乙硫氨酸、吖啶黄、普鲁卡因和肉桂醛）都是Tn10精确切除的有效抑制剂，因此可以被定义为抗诱变剂。
