Ma Liqiu, Kazama Yusuke, Hirano Tomonari, Morita Ryouhei, Tanaka Shuuitsu, Abe Tomoko, Hatakeyama Shin
a Laboratory of Genetics, Department of Regulatory Biology, Faculty of Science , Saitama University , Saitama , Japan.
b RIKEN Nishina Center , Saitama , Japan.
Int J Radiat Biol. 2018 Dec;94(12):1125-1133. doi: 10.1080/09553002.2019.1524940. Epub 2018 Oct 11.
To assess the unique biological effects of different forms of ionizing radiation causing DNA double-strand breaks (DSBs), we compared the killing effect, mutagenesis frequency, and mutation type spectrum using the model filamentous fungus Neurospora.
Asexual spores of wild-type Neurospora and two DSB repair-deficient strains [one homologous recombination- and the other non-homologous end-joining (NHEJ) pathway-deficient] were irradiated with argon (Ar)-ion beams, ferrous (Fe)-ion beams, or X-rays. Relative biological effectiveness (RBE), forward mutation frequencies at the ad-3 loci, and mutation spectra at the ad-3B gene were determined.
The canonical NHEJ (cNHEJ)-deficient strain showed resistance to higher X-ray doses, while other strains showed dose-dependent sensitivity. In contrast, the killing effects of Ar-ion and Fe-ion beam irradiation were dose-dependent in all strains tested. The rank order of RBE was Ar-ion > Fe-ion > C-ion. Deletion mutations were the most common, but deletion size incremented with the increasing value of linear energy transfer (LET).
We found marked differences in killing effect of a cNHEJ-deficient mutant between X-ray and high-LET ion beam irradiations (Ar and Fe). The mutation spectra also differed between irradiation types. These differences may be due to the physical properties of each radiation and the repair mechanism of induced damage in Neurospora crassa. These results may guide the choice of irradiation beam to kill or mutagenize fungi for agricultural applications or further research.
为了评估导致DNA双链断裂（DSB）的不同形式电离辐射的独特生物学效应，我们使用丝状真菌粗糙脉孢菌模型比较了杀伤效应、诱变频率和突变类型谱。
用氩（Ar）离子束、铁（Fe）离子束或X射线照射野生型粗糙脉孢菌的无性孢子以及两种DSB修复缺陷菌株[一种是同源重组缺陷型，另一种是非同源末端连接（NHEJ）途径缺陷型]。测定相对生物学效应（RBE）、ad-3位点的正向突变频率以及ad-3B基因的突变谱。
cNHEJ缺陷型菌株对较高剂量的X射线表现出抗性，而其他菌株表现出剂量依赖性敏感性。相比之下，在所有测试菌株中，Ar离子和Fe离子束照射的杀伤效应均呈剂量依赖性。RBE的排序为Ar离子＞Fe离子＞C离子。缺失突变最为常见，但缺失大小随线能量转移（LET）值的增加而增大。
我们发现cNHEJ缺陷型突变体在X射线和高LET离子束照射（Ar和Fe）之间的杀伤效应存在显著差异。不同照射类型的突变谱也有所不同。这些差异可能归因于每种辐射的物理特性以及粗糙脉孢菌中诱导损伤的修复机制。这些结果可能为农业应用或进一步研究中选择用于杀死或诱变真菌的照射束提供指导。
