Tucker J D, Breneman J W, Briner J F, Eveleth G G, Langlois R G, Moore D H
Biology and Biotechnology Research Program, Lawrence Livermore National Laboratory, Livermore, California 94551, USA.
Environ Mol Mutagen. 1997;30(3):264-72. doi: 10.1002/(sici)1098-2280(1997)30:3<264::aid-em4>3.0.co;2-l.
In this article, we address the issue of persistence of chromosome exchanges following acute in vitro exposure of rat peripheral blood to 137Cs. Irradiation occurred 24 hr after culture initiation, and metaphase chromosomes were prepared 2, 3, 4, and 5 days later. Chromosomes 1, 2, and 4 were painted in unique colors and scored for structural aberrations. Dicentric chromosomes and acentric fragments diminished rapidly with time, as expected. Translocations exhibited greater persistence, but still showed a reduction in frequency, reaching a plateau of approximately 65 and 55% of their initial values, 4 days after exposure to 1 and 2 Gy, respectively. An exponentially declining model was fit to the combined dicentric, acentric fragment, and translocation frequencies, which showed that all three aberration types declined at equivalent rates. The frequencies of dicentrics and fragments declined to a plateau of zero, while translocations reached a plateau at frequencies significantly greater than zero. The decline in translocations with time is inconsistent with prevailing theoretical expectations, but is consistent with a model where some translocations are fully stable (persistent) and some are unstable (not persistent) through cell division. These results may have implications for radiation biodosimetry in humans.
在本文中，我们探讨了大鼠外周血在体外急性暴露于137Cs后染色体交换的持续性问题。照射在培养开始24小时后进行，在2、3、4和5天后制备中期染色体。用独特的颜色对1号、2号和4号染色体进行标记，并对结构畸变进行评分。正如预期的那样，双着丝粒染色体和无着丝粒片段随时间迅速减少。易位表现出更大的持续性，但频率仍有下降，在分别暴露于1 Gy和2 Gy后4天，易位频率分别达到其初始值的约65%和55%的平台期。将指数衰减模型应用于双着丝粒、无着丝粒片段和易位频率的总和，结果表明所有三种畸变类型以相同的速率下降。双着丝粒和片段的频率下降到零的平台期，而易位在频率显著大于零的情况下达到平台期。易位频率随时间的下降与当前的理论预期不一致，但与一个模型一致，即一些易位在细胞分裂过程中是完全稳定的（持续性的），而一些是不稳定的（非持续性的）。这些结果可能对人类辐射生物剂量测定有影响。
