RADIATION-INDUCED STRAND BREAKS IN PHI-X174 REPLICATIVE FORM DNA - AN IMPROVED EXPERIMENTAL AND THEORETICAL APPROACH
RADIATION-INDUCED STRAND BREAKS IN PHI-X174 REPLICATIVE FORM DNA - AN IMPROVED EXPERIMENTAL AND THEORETICAL APPROACH
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DOI：
10.1080/09553008514551621
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发表时间：
1985-01-01
影响因子：
2.6
通讯作者：
LOMAN, H
中科院分区：
文献类型：
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作者：
VANTOUW, JH;VERBERNE, JB;LOMAN, H
为了确定辐射诱导的单链、双链和潜在断裂（通过碱或热处理转化为实际断裂的断裂）的产率，用增加剂量的γ-辐射照射含氧的AZX 174超螺旋环状双链（RFI）DNA水溶液，并在热处理前后在琼脂糖凝胶上进行电泳。获得RFI、RFII（由于一个或多个单链断裂的松弛环）和RFIII（由于一个双链断裂的线性DNA）的完全分离。开发了一种计算机辅助分光光度法程序，这使我们能够非常准确地测量存在于三个DNA组分中的DNA的量。DNA各组分含量随剂量的变化符合一个简单的统计模型，该模型描述了不同类型断裂的形成与剂量的依赖关系，由此可计算出单链、潜在单链和双链断裂的D_（37）值分别为0.42 ± 0.02、1.40 ± 0.25和57 ± 36戈伊。在我们的条件下，潜在的双链断裂没有显著形成。此外，可以确定导致双链断裂的相对链中两个独立引入的单链断裂之间的最大距离。热处理前后的值分别为29 ± 6和102 ± 13个核苷酸。
To determine the yield of radiation-induced single-strand, double-strand and potential breaks (breaks which are converted into actual breaks by alkali or heat treatment) oxygenated aqueous solutions of ϕX174 supercoiled circular double-stranded (RFI) DNA were irradiated with increasing doses of γ-irradiation and subjected to electrophoresis on agarose gels both before and after heat treatment. A complete separation was obtained of RFI, RFII (relaxed circle due to one or more single-strand breaks) and RFIII (linear DNA due to one double-strand break). A computer-assisted spectrophotometric procedure was developed, which enabled us to measure very accurately the amount of DNA present in the three DNA fractions. The quantitative changes of each fraction of DNA with dose could be fitted to a straightforward statistical model, which described the dose-dependent formation of the different types of breaks and from which theD37-values of single-strand, potential single-strand and double-strand breaks could be calculated to be 0·42 ± 0·02, 1·40 ± 0·25 and 57 ± 36 Gy respectively. Potential double-strand breaks were not formed significantly under our conditions. In addition the maximum distance between two independently introduced single-strand breaks in opposite strands resulting in a double-strand break could be determined. The values before and after heat treatment are shown to be 29 ± 6 and 102 ± 13 nucleotides, respectively.