0.5 MeV单能中子照射洋葱干种子后在根尖细胞内诱发微核的相对生物效应

目的 了解0.5 MeV单能中子照射洋葱干种子后在根尖细胞中诱发微核的相对生物效应(RBE)。方法 通过由加速器产生的0.5M eV单能中子和⁶⁰Co γ射线照射洋葱干种子,观察这两种辐射在根尖细胞中微核诱发率的差异。结果 单位剂量0.5 MeV中子和⁶⁰Co γ射线的微核诱发率分别为4.36±0.17和0.031±0.002(% Gy^-1)。因此,0.5 MeV单能中子照射洋葱干种子后在根尖细胞中诱发微核的RBE值为141±11。结论 0.5M eV单能中子照射洋葱干种子后在根尖细胞中诱发微核的RBE值高达141±11,一方面是由于低氧效应,另一方面就是中子照射所致DNA损伤的修复效率可能远远低于?射线照射所致的DNA损伤的修复效率。

The Relative Biological Effectiveness of 0.5 MeV Neutrons to Induce Micronuclei in the Root-tip Cells of Onion Seedlings After Irradiation as Dry Dormant Seeds

Objective To best understand the relative biological effectiveness (RBE) of 0.5 MeV neutrons to induce micronuclei in the root-tip cells after irradiation as dry dormant seeds.Methods To observe the difference of the frequencies of micronuclei induced in the root-tip cells of onion seedlings after irradiation as dry dormant seeds by 0.5 MeV neutrons from an accelerator and by γ rays from a ⁶⁰Co source.Results The frequencies of micronuclei induced by unit dose of 0.5 MeV mono-energetic neutrons from an accelerator and γ rays from a ⁶⁰Co source are 4.36 ±0.17 and 0.031 ±0.002 (%Gy^-1), respectively. Thus, the RBE value for 0.5MeV mono-energetic neutrons to induce micronuclei in the root-tip cells of onion seedlings irradiated as dry dormant seeds is about 141 ±11.Conclusion The RBE value of 0.5 MeV mono-energetic neutrons to induce micronuclei in the root-tip cells of Allium cepa onion seedlings irradiated as dry dormant seeds is as high as 141 ±11. Our findings suggested that the repair efficiency of DNA damage induced by mono-energetic neutrons may be lower than that by γrays.