Filippov V D, Zagoruiko E E
Mutat Res. 1978 Oct;52(1):49-56. doi: 10.1016/0027-5107(78)90094-5.
The frequency of UV-induced extragenic suppressor reversions to leucine independence in B. subtilis carrying a leu8 mutation decreased when irradiated cells were temporarily incubated in medium deprived of nitrogen sources. This mutation frequency decline (MFD) was inhibited by acriflavine and was poorly expressed in a uvr1 mutant. Consequently, MFD may be considered as the manifestation of an anti-mutagenic activity of excision repair. MFD was decelerated and even vanished in cells subjected to prolonged starvation of nitrogen sources before irradiation. MFD was accelerated in bacteria that were first irradiated and incubated in nutritional medium for at least 30 min. The stimulation of MFD by UV exposure was observed only in the uvr+ strain and depended on protein synthesis after irradiation. It is assumed that different rates of MFD in cells of various pre-radiation histories reflect different levels of the excision-repair activity inherent in these cells.
携带leu8突变的枯草芽孢杆菌中，紫外线诱导的回复为亮氨酸非依赖型的基因外抑制性回复突变频率，在照射后的细胞于缺乏氮源的培养基中短暂孵育时会降低。这种突变频率下降（MFD）受到吖啶黄素的抑制，并且在uvr1突变体中表现不佳。因此，MFD可被视为切除修复抗诱变活性的表现。在照射前经历长时间氮源饥饿的细胞中，MFD减缓甚至消失。在首先进行照射并在营养培养基中孵育至少30分钟的细菌中，MFD加速。紫外线照射对MFD的刺激仅在uvr +菌株中观察到，并且依赖于照射后的蛋白质合成。据推测，不同预辐射历史的细胞中MFD的不同速率反映了这些细胞中固有的切除修复活性的不同水平。
