Yokota Yuichiro, Yamada Shinya, Hase Yoshihiro, Shikazono Naoya, Narumi Issay, Tanaka Atsushi, Inoue Masayoshi
Gene Resource Research Group, Quantum Beam Science Directorate, Japan Atomic Energy Agency, Takasaki, Gunma 370-1292, Japan.
Radiat Res. 2007 Jan;167(1):94-101. doi: 10.1667/RR0701.1.
The ability of ion beams to kill or mutate plant cells is known to depend on the linear energy transfer (LET) of the ions, although the mechanism of damage is poorly understood. In this study, DNA double-strand breaks (DSBs) were quantified by a DNA fragment-size analysis in tobacco protoplasts irradiated with high-LET ions. Tobacco BY-2 protoplasts, as a model of single plant cells, were irradiated with helium, carbon and neon ions having different LETs and with gamma rays. After irradiation, DNA fragments were separated into sizes between 1600 and 6.6 kbp by pulsed-field gel electrophoresis. Information on DNA fragmentation was obtained by staining the gels with SYBR Green I. Initial DSB yields were found to depend on LET, and the highest relative biological effectiveness (about 1.6) was obtained at 124 and 241 keV/microm carbon ions. High-LET carbon and neon ions induced short DNA fragments more efficiently than gamma rays. These results partially explain the large biological effects caused by high-LET ions in plants.
尽管对离子束损伤植物细胞的机制了解甚少，但已知离子束杀死或使植物细胞发生突变的能力取决于离子的传能线密度（LET）。在本研究中，通过对经高传能线密度离子辐照的烟草原生质体进行DNA片段大小分析，对DNA双链断裂（DSB）进行了定量。作为单个植物细胞模型的烟草BY - 2原生质体，用具有不同传能线密度的氦离子、碳离子和氖离子以及γ射线进行辐照。辐照后，通过脉冲场凝胶电泳将DNA片段分离为1600至6.6千碱基对之间的大小。用SYBR Green I对凝胶染色，获取有关DNA片段化的信息。发现初始双链断裂产率取决于传能线密度，在124和241 keV/微米的碳离子处获得了最高相对生物效能（约1.6）。高传能线密度的碳离子和氖离子比γ射线更有效地诱导短DNA片段。这些结果部分解释了高传能线密度离子在植物中引起的巨大生物学效应。
