Tsuruoka Chizuru, Suzuki Masao, Fujitaka Kazunobu
International Space Radiation Laboratory, National Institute Radiological Sciences.
Biol Sci Space. 2004 Nov;18(3):188-9.
We have been studying LET and ion species dependence of RBE in mutation frequency and mutation spectrum of deletion pattern of exons in hprt locus. Normal human skin fibroblasts were irradiated with heavy-ion beams, such as carbon- (290 MeV/u and 135 MeV/u), neon- (230 MeV/u and 400 MeV/u), silicon- (490 MeV/u) and iron- (500 MeV/u) ion beams, generated by Heavy Ion Medical Accelerator in Chiba (HIMAC) at national Institute of Radiological Sciences (NIRS). Mutation induction in hprt locus was detected to measure 6-thioguanine resistant colonies and deletion spectrum of exons was analyzed by multiplex PCR. The LET-RBE curves of mutation induction for carbon- and neon-ion beams showed a peak around 75 keV/micrometers and 155 keV/micrometers, respectively. On the other hand, there observed no clear peak for silicon-ion beams. The deletion spectrum of exons was different in induced mutants among different ion species. These results suggested that quantitative and qualitative difference in mutation occurred when using different ion species even if similar LET values.
我们一直在研究传能线密度（LET）和离子种类对人次黄嘌呤磷酸核糖转移酶（hprt）基因座外显子缺失模式的突变频率和突变谱中相对生物学效应（RBE）的影响。使用日本国立放射科学研究所（NIRS）的千叶重离子医学加速器（HIMAC）产生的碳离子（290 MeV/u和135 MeV/u）、氖离子（230 MeV/u和400 MeV/u）、硅离子（490 MeV/u）和铁离子（500 MeV/u）束辐照正常人皮肤成纤维细胞。通过检测6-硫鸟嘌呤抗性集落来检测hprt基因座中的突变诱导情况，并通过多重聚合酶链反应（PCR）分析外显子的缺失谱。碳离子束和氖离子束的突变诱导LET-RBE曲线分别在75 keV/微米和155 keV/微米左右出现峰值。另一方面，硅离子束未观察到明显的峰值。不同离子种类诱导的突变体中外显子的缺失谱不同。这些结果表明，即使传能线密度值相似，使用不同离子种类时，突变在数量和质量上也会存在差异。
