LINEAR INDUCTION OF DNA DOUBLE-STRAND BREAKAGE WITH X-RAY DOSE, AS DETERMINED FROM DNA FRAGMENT SIZE DISTRIBUTION
LINEAR INDUCTION OF DNA DOUBLE-STRAND BREAKAGE WITH X-RAY DOSE, AS DETERMINED FROM DNA FRAGMENT SIZE DISTRIBUTION
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DOI：
10.2307/3579023
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发表时间：
1995-05-01
影响因子：
3.4
通讯作者：
CEDERVALL, B
中科院分区：
文献类型：
--
作者：
ERIXON, K;CEDERVALL, B
脉冲场凝胶电泳已被应用于分离DNA从小鼠L1210细胞暴露于1至50戈伊的X射线剂量。同时分离的标记染色体在0.1至12.6 Mbp的范围内允许的辐射诱导的片段的大小分布的计算。该分布与双链断裂（DSB）的随机诱导一致。此类片段的大小分布与诱导断裂的平均数之间的理论关系用于计算产率和剂量响应。通过放射性标记和荧光染色确定DNA分布。使用两种独立的方法来评估辐射诱导的DSB产量，这两种方法都假设所有DNA随机断裂。在第一种方法中，我们比较了低于给定大小限制的DNA的理论和实验分数。通过这种方法，我们估计使用放射性标记的产量为0.006-0.007 DSB/戈伊/百万碱基对，通过荧光染色的产量为0.004-0.008 DSB/戈伊/百万碱基对。在第二种方法中，我们只观察凝胶分辨部分的尺寸分布，并将其与理论分布进行比较。通过这种方法，使用荧光作为DNA分布的量度，发现约为0.012 DSB/戈伊/Mbp的值。在大小为6000 Mbp的正常二倍体哺乳动物基因组中，这分别相当于25-50 DSB/戈伊或70 DSB/戈伊的产量。第二种方法，它只看较小的片段，可能高估的产量，而第一种方法遭受的不确定性的DNA不可逆地困在井的分数。该测定具有检测小于1戈伊的剂量的能力。(C)1995年，辐射研究学会
Pulsed-field gel electrophoresis has been applied to separate DNA from mouse L1210 cells exposed to X-ray doses of 1 to 50 Gy. Simultaneous separation of marker chromosomes in the range 0.1 to 12.6 Mbp allowed calculation of the size distribution of the radiation-induced fragments. The distribution was consistent with a random induction of double-strand breaks (DSBs), A theoretical relationship between the size distribution of such fragments and the average number of induced breaks was used to calculate the yield and dose response. The DNA distribution was determined by both radiolabeling and fluorescence staining, Two independent methods were used to evaluate the radiation-induced yield of DSBs, both assuming that all DNA is broken at random. In the first method we compared the theoretical and experimental fraction of DNA that is below a given size limit. By this method we estimated the yield to be 0.006-0.007 DSB/Gy per million base pairs using the radiolabel and 0.004-0.008 DSB/Gy per million base pairs by fluorescence staining. The dose response was linear in both cases, In the second method we looked only at the size distribution in the resolving part of the gel and compared it to the theoretical distribution, By this method a value of approximately 0.012 DSB/Gy/Mbp was found, using fluorescence as a measure of DNA distribution. In a normal diploid mammalian genome of size 6000 Mbp, this is equivalent to a yield of 25-50 DSBs/Gy or 70 DSBs/Gy, respectively. The second approach, which looks only at the smaller fragments, may overestimate the yield, while the first approach suffers from uncertainties about the fraction of DNA irreversibly trapped in the well. The assay has the capacity to detect a dose of less than I Gy. (C) 1995 by Radiation Research Society