Watanabe M, Suzuki M, Suzuki K, Nakano K, Yatagai F
Division of Radiation Biology, School of Medicine, Yokohama City University, Japan.
J Radiat Res. 1992 Mar;33 Suppl:87-94. doi: 10.1269/jrr.33.supplement_87.
We studied radiation-induced chromosome fragmentation in the G1-phase of Syrian golden hamster embryo (SHE) cells by premature chromosome condensation (PCC). SHE cells were irradiated with 14N ions (95 MeV) and 4He ions (22 MeV) generated by the cyclotron and 137Cs gamma rays. The number of chromosome breaks in PCC (PCC break) induced by 14N ions was higher than in those by the others. High linear energy transfer (LET) radiation (heavy ions) is more effective in the induction of PCC breaks than low LET radiation (gamma-rays). 530 kev/microns 14N induced PCC 2.4 times more than 137Cs gamma rays. There is an inverse relationship between the number of chromatid deletions and the incidence of mutation or transformation. There is, however, a good correlation between the incidence of PCC breaks and frequencies of mutation and/or morphological transformation. Although over 95% of the PCC breaks induced by gamma-rays were rejoined within 8 hours of post-irradiation incubation, only 35 to 45% of PCC breaks induced by heavy ions were rejoined. These results suggest that there is a qualitative difference in the initial chromosome damage caused by heavy ions and gamma rays.
我们通过早熟染色体凝集（PCC）研究了叙利亚金仓鼠胚胎（SHE）细胞G1期的辐射诱导染色体断裂。用回旋加速器产生的14N离子（95 MeV）、4He离子（22 MeV）和137Csγ射线照射SHE细胞。14N离子诱导的PCC（PCC断裂）中的染色体断裂数高于其他离子诱导的。高传能线密度（LET）辐射（重离子）比低LET辐射（γ射线）在诱导PCC断裂方面更有效。530 kev/微米的14N诱导的PCC比137Csγ射线多2.4倍。染色单体缺失数与突变或转化发生率之间呈负相关。然而，PCC断裂发生率与突变频率和/或形态转化频率之间存在良好的相关性。虽然γ射线诱导的PCC断裂在照射后培养8小时内超过95%得到重新连接，但重离子诱导的PCC断裂只有35%至45%得到重新连接。这些结果表明，重离子和γ射线引起的初始染色体损伤存在质的差异。
