Ryu Tae Ho, Kim Jin Kyu, Kim Jeong-Il, Kim Jin-Hong
Advanced Radiation Technology Institute, Korea Atomic Energy Research Institute, 29 Geumgu-gil, Jeongeup-si, Jeollabuk-do 56212, Republic of Korea; Department of Biotechnology, Chonnam National University, 77 Yongbong-ro, Buk-gu, Gwangju 61186, Republic of Korea.
Advanced Radiation Technology Institute, Korea Atomic Energy Research Institute, 29 Geumgu-gil, Jeongeup-si, Jeollabuk-do 56212, Republic of Korea; Department of Radiation Biotechnology and Applied Radioisotope Science, University of Science and Technology, 217 Gajeong-ro, Yuseong-gu, Daejeon 34113, Republic of Korea.
J Environ Radioact. 2018 Jan;181:94-101. doi: 10.1016/j.jenvrad.2017.11.007. Epub 2017 Nov 9.
Plants are used as representative reference biota for the biological assessment of environmental risks such as ionizing radiation due to their immobility. This study proposed a faster, more economical, and more effective method than conventional cytogenetic methods for the biological dosimetry of ionizing radiation in plants (phytodosimetry). We compared various dose-response curves for the radiation-induced DNA damage response (DDR) in Arabidopsis thaliana after relatively "low-dose" gamma irradiation (3, 6, 12, 24, and 48 Gy) below tens of Gy using comet (or single-cell gel electrophoresis), gamma-H2AX, and transcriptomic assays of seven DDR genes (AGO2, BRCA1, GRG, PARP1, RAD17, RAD51, and RPA1E) using quantitative real time PCR. The DDR signal from the comet assay was saturated at 6 Gy, while the gamma-H2AX signal increased up to 48 Gy, following a linear-quadratic dose-response model. The transcriptional changes in the seven DDR genes were fitted to linear or supra-linear quadratic equations with significant dose-dependency. The dose-dependent transcriptional changes were maintained similarly until 24 h after irradiation. The integrated transcriptional dose-response model of AGO2, BRCA1, GRG, and PARP1 was very similar to that of gamma-H2AX, while the transcriptional changes in the BRCA1, GRG, and PARP1 DDR genes revealed significant dependency on the dose-rate, ecotype, and radiation dose. These results suggest that the transcriptome-based dose-response model fitted to a quadratic equation could be used practically for phytodosimetry instead of conventional cytogenetic models, such as the comet and gamma-H2AX assays. The effects of dose-rate and ecotype on the transcriptional changes of DDR genes should also be considered to improve the transcriptome-based phytodosimetry model.
由于植物的固定性，它们被用作生物评估环境风险（如电离辐射）的代表性参考生物群。本研究提出了一种比传统细胞遗传学方法更快、更经济、更有效的植物电离辐射生物剂量测定方法（植物剂量测定法）。我们比较了在低于数十戈瑞的相对“低剂量”γ辐射（3、6、12、24和48戈瑞）后，拟南芥中辐射诱导的DNA损伤反应（DDR）的各种剂量反应曲线，使用彗星试验（或单细胞凝胶电泳）、γ-H2AX以及使用定量实时PCR对七个DDR基因（AGO2、BRCA1、GRG、PARP1、RAD17、RAD51和RPA1E）进行转录组分析。彗星试验的DDR信号在6戈瑞时饱和，而γ-H2AX信号在48戈瑞时仍遵循线性二次剂量反应模型增加。七个DDR基因的转录变化符合具有显著剂量依赖性的线性或超线性二次方程。剂量依赖性转录变化在照射后24小时内保持相似。AGO2、BRCA1、GRG和PARP1的综合转录剂量反应模型与γ-H2AX非常相似，而BRCA1、GRG和PARP1 DDR基因的转录变化显示出对剂量率、生态型和辐射剂量的显著依赖性。这些结果表明，拟合二次方程的基于转录组的剂量反应模型可实际用于植物剂量测定，而不是传统的细胞遗传学模型，如彗星试验和γ-H2AX试验。为了改进基于转录组的植物剂量测定模型，还应考虑剂量率和生态型对DDR基因转录变化的影响。
