Nagasawa H, Little J B
Department of Cancer Cell Biology, Harvard School of Public Health, 665 Huntington Avenue, Boston, Massachusetts 02115, USA.
Radiat Res. 1999 Nov;152(5):552-7.
We examined the induction of HPRT mutations in CHO cells exposed to low fluences of (238)Pu alpha particles from a specially constructed irradiator. The dose-response relationship was linear over the dose range of 5 cGy-1.2 Gy. However, unexpected sensitivity, leading to a significantly higher frequency of mutations than would be predicted by a back extrapolation from the data for higher doses, was observed in the dose range below 5 cGy, where the mean number of alpha-particle traversals per nucleus was significantly less than one (0.05-0.3). The frequency of mutations induced by a single alpha particle traversing the nucleus of a cell was increased nearly fivefold at the lowest fluence studied. The data are consistent with the conclusion that the enhanced efficiency of each nuclear traversal at low particle fluences is the result of mutations arising in nonirradiated, bystander cells.
我们检测了暴露于来自特制辐照器的低注量(238)Puα粒子的CHO细胞中HPRT突变的诱导情况。在5 cGy至1.2 Gy的剂量范围内，剂量-反应关系呈线性。然而，在低于5 cGy的剂量范围内观察到意外的敏感性，导致突变频率显著高于根据较高剂量数据反向推断所预测的频率，在此剂量范围内每个细胞核α粒子穿越的平均次数显著少于一次(0.05 - 0.3)。在研究的最低注量下，单个α粒子穿越细胞核诱导的突变频率增加了近五倍。这些数据与以下结论一致，即低粒子注量下每次细胞核穿越效率的提高是未受辐照的旁观者细胞中产生突变的结果。
