Durante M, Furusawa Y, George K, Gialanella G, Greco O, Grossi G, Matsufuji N, Pugliese M, Yang T C
Dipartimento di Scienze Fisiche, Università Federico II, Monte S. Angelo, Napoli, Italy.
Radiat Res. 1998 May;149(5):446-54.
We have recently reported the kinetics of chromosome rejoining and exchange formation in human lymphocytes exposed to gamma rays using the techniques of fluorescence in situ hybridization (FISH) and premature chromosome condensation (PCC). In this paper, we have extended previous measurements to cells exposed to charged particles. Our goal was to determine differences in chromatin break rejoining and misrejoining after exposure to low- and high-linear energy transfer (LET) radiation. Cells were irradiated with hydrogen, neon, carbon or iron ions in the LET range 0.3-140 keV/microm and were incubated at 37 degrees C for various times after exposure. Little difference was observed in the yield of early prematurely condensed chromosome breaks for the different ions. The kinetics of break rejoining was exponential for all ions and had similar time constants, but the residual level of unrejoined breaks after prolonged incubation was higher for high-LET radiation. The kinetics of exchange formation was also similar for the different ions, but the yield of chromosome interchanges measured soon after exposure was higher for high-LET particles, suggesting that a higher fraction of DNA breaks are misrejoined quickly. On the other hand, the rate of formation of complete exchanges was slightly lower for densely ionizing radiation. The ratios between the yields of different types of aberrations observed at 10 h postirradiation in prematurely condensed chromosome preparations were dependent on LET. We found significant differences between the yields of aberrations measured in interphase (after repair) and metaphase for densely ionizing radiation. This difference might be caused by prolonged mitotic delay and/or interphase death. Overall, the results point out significant differences between low- and high-LET radiation for the formation of chromosome aberrations.
我们最近报道了利用荧光原位杂交（FISH）技术和早熟染色体凝聚（PCC）技术，研究暴露于γ射线的人淋巴细胞中染色体重新连接和交换形成的动力学。在本文中，我们将先前的测量扩展到暴露于带电粒子的细胞。我们的目标是确定暴露于低线性能量传递（LET）和高线性能量传递辐射后染色质断裂重新连接和错误重新连接的差异。用氢、氖、碳或铁离子在0.3 - 140 keV/μm的LET范围内对细胞进行辐照，并在暴露后于37℃孵育不同时间。对于不同的离子，早期早熟凝聚染色体断裂的产额几乎没有差异。所有离子的断裂重新连接动力学都是指数形式的，并且具有相似的时间常数，但是对于高线性能量传递辐射，长时间孵育后未重新连接的断裂的残留水平更高。不同离子的交换形成动力学也相似，但是暴露后不久测量的染色体互换产额对于高线性能量传递粒子更高，这表明更高比例的DNA断裂被快速错误重新连接。另一方面，对于密集电离辐射，完全交换的形成速率略低。在早熟凝聚染色体标本中辐照后10小时观察到的不同类型畸变产额之间的比率取决于LET。我们发现对于密集电离辐射，在间期（修复后）和中期测量的畸变产额之间存在显著差异。这种差异可能是由延长的有丝分裂延迟和/或间期死亡引起的。总体而言，结果指出了低LET和高LET辐射在染色体畸变形成方面的显著差异。
