Mechanism of the induction of DNA strand breaks by low energy radiation

低能辐射诱导DNA链断裂的机制

• 批准号: 10044217
• 负责人: HIEDA Koutarou
• 金额: $ 3.71万
• 依托单位: RIKKYO UNIVERSITY
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (B).
• 财政年份: 1998
• 资助国家: 日本
• 起止时间: 1998 至 1999
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-10044217/
• 关键词: DNA; single-strand break; double-strand break; radiation; electron; vacuum-UV; plasmid; low energy; 主鎖切断; 電子; 単色真空紫外線

Most energy of ionizing radiation transfers to many low energy secondary electrons, and then they produce most radiobiological effects. Vacuum-and far-UV photons provide an unique tool to control the energy absorbing processes, excitation and ionization. Monochromatic low energy electrons and photons, thus, are essential to elucidate mechanism of radiobiological effects, but, however, they are scarcely used in radiation biology because of lack of convenient sources. Our project is an international cooperation to elucidate mechanism of the induction of DNA strand breaks using two unique radiation sources : monochromatic low energy electrons (Gray Laboratory, UK) and monochromatic vacuum-UV photons (Photon Factory, Japan). Major results on the strand break induction in plasmid DNA are as follows ; (1) electrons as low as 15 Ev induced ssb and dsb linearly with the fluence, indicating that the threshold energy for the induction of ssb and dsb is below 15 Ev ; experimental determination of the value for dsb is one of the major result of this project. (2) The ratio of dsb / ssb was about 0.01, which was similar to that for ィイD160ィエD1Co γ-rays. (3) Low energy photons down to 4.3 Ev (the lowest energy tested) induced ssb and dsb with very low quantum yield. This result indicated that the threshold energy was lower than 4.3 Ev in this sense, but that defined usual was about 10 Ev. (4) We irradiated plasmid DNA in buffer solution by vacuum-UV photons using the method that was developed in the Gray Laboratory ; monochromatic 7-Ev photons induced ssb and dsb. (5) These threshold energies are crucially important to simulation calculation of models for DNA strand break.

电离辐射的大部分能量转移到许多低能的次级电子上，产生最大的辐射生物效应。紫外和远紫外光子提供了一种独特的工具来控制能量吸收过程，激发和电离。单色低能电子和光子是阐明辐射生物学效应机理的重要手段，但由于缺乏方便的辐射源，它们在辐射生物学中的应用很少。我们的项目是一项国际合作，使用两种独特的辐射源来阐明诱导DNA链断裂的机制：单色低能电子（Gray Laboratory，UK）和单色真空紫外光子（Photon Factory，Japan）。质粒DNA链断裂诱导的主要结果如下：（1）低至15 Ev的电子诱导ssb和dsb与能量密度成线性关系，表明诱导ssb和dsb的阈值能量低于15 Ev，dsb值的实验测定是本项目的主要结果之一。(2)dsb / ssb的比值约为0.01，与γ射线的dsb/ssb比值相近。(3)低至4.3 Ev（测试的最低能量）的低能量光子以非常低的量子产率诱导ssb和dsb。这一结果表明，在这个意义上，阈值能量低于4.3 Ev，而通常定义的阈值能量约为10 Ev。(4)我们照射质粒DNA在缓冲液中的真空紫外光子使用的方法，在灰色实验室开发的;单色7-Ev光子诱导的SSB和dsb。(5)这些阈值能量对于DNA链断裂模型的模拟计算是至关重要的。

项目成果

R.Hanai,M.Yazu and K.Hieda.: "On the experimental distinction between ssbs and bsbs in circular DNA"International Journal of Radiation Biology. 73. 475-479 (1988)

R.Hanai、M.Yazu 和 K.Hieda.：“关于环状 DNA 中 ssbs 和 bsbs 的实验区别”国际放射生物学杂志。

K.Hieda et al.,: "Do Auger events of phosphorus by monochromatic X-rays induce DNA double-strand breaks efficiently?"Proceedings of 11^<th> International Conference of Radiation Research. (in press). (2000)

K.Hieda 等人，“单色 X 射线磷的俄歇事件是否有效诱导 DNA 双链断裂？”第 11 届国际辐射研究会议论文集。

K.Hieda: "Do Auger events by monochromatic X-rays induce DNA double-strand breaks efficiently?"Proceedings of 11th International Congress of Radiation Research. (in press). (2000)

K.Hieda：“单色 X 射线的俄歇事件是否能有效诱导 DNA 双链断裂？”第 11 届国际辐射研究大会论文集。

R.Hanai, M.Yazu and K.Hieda: "On the experimental distinction between ssbs and dsbs in circular DNA."Int. J. Radiat. Biol.. 73. 475-479 (1998)

R.Hanai、M.Yazu 和 K.Hieda：“关于环状 DNA 中 ssbs 和 dsbs 的实验区别”。