Rithidech K Noy, Honikel L, Whorton E B
Pathology Department, Stony Brook University, Stony Brook, NY 11794-8691, USA.
Radiat Environ Biophys. 2007 Jun;46(2):137-45. doi: 10.1007/s00411-006-0092-x. Epub 2007 Feb 14.
To date, there is scant information on in vivo induction of chromosomal damage by heavy ions found in space (i.e. 56Fe ions). For radiation-induced response to be useful for risk assessment, it must be established in in vivo systems especially in cells that are known to be at risk for health problems associated with radiation exposure (such as hematopoietic cells, the known target tissue for radiation-induced leukemia). In this study, the whole genome multicolor fluorescence in situ hybridization (mFISH) technique was used to examine the in vivo induction of chromosomal damage in hematopoietic tissues, i.e. bone marrow cells. These cells were collected from CBA/CaJ mice at day 7 following whole-body exposure to different doses of 1 GeV/amu 56Fe ions (0, 0.1, 0.5 and 1.0 Gy) or (137)Cs gamma rays as the reference radiation (0, 0.5, 1.0 and 3.0 Gy, at the dose rate of 0.72 Gy/min using a GammaCell40). These radiation doses were the average total-body doses. For each radiation type, there were four mice per dose. Several types of aberrations in bone marrow cells collected from mice exposed to either type of radiation were found. These were exchanges and breaks (both chromatid- and chromosome-types). Chromosomal exchanges included translocations (Robertsonian or centric fusion, reciprocal and incomplete types), and dicentrics. No evidence of a non-random involvement of specific chromosomes in any type of aberrations observed in mice exposed to 56Fe ions or 137Cs gamma rays was found. At the radiation dose range used in our in vivo study, the majority of exchanges were simple. Complex exchanges were detected in bone marrow cells collected from mice exposed to 1 Gy of 56Fe ions or 3 Gy of 137Cs gamma rays only, but their frequencies were low. Overall, our in vivo data indicate that the frequency of complex chromosome exchanges was not significantly different between bone marrow cells collected from mice exposed to 56Fe ions or 137Cs gamma rays. Each type of radiation induced significant dose-dependent increases (ANOVA, P < 0.01) in the frequencies of chromosomal damage, including the numbers of abnormal cells. Based upon the linear-terms of dose-response curves, 56Fe ions were 1.6 (all types of exchanges), 4.3 (abnormal cells) and 4.2 (breaks, both chromatid- and chromosome-types) times more effective than 137Cs gamma rays in inducing chromosomal damage.
迄今为止，关于空间中发现的重离子（即56Fe离子）在体内诱导染色体损伤的信息很少。为了使辐射诱导反应有助于风险评估，必须在体内系统中建立，特别是在已知会因辐射暴露而出现健康问题的细胞中（如造血细胞，它是辐射诱导白血病的已知靶组织）。在本研究中，采用全基因组多色荧光原位杂交（mFISH）技术检测造血组织（即骨髓细胞）中染色体损伤的体内诱导情况。这些细胞是在全身暴露于不同剂量的1 GeV/amu 56Fe离子（0、0.1、0.5和1.0 Gy）或（137）Csγ射线（作为参考辐射，剂量分别为0、0.5、1.0和3.0 Gy，使用GammaCell40以0.72 Gy/min的剂量率照射）7天后从CBA/CaJ小鼠身上采集的。这些辐射剂量是平均全身剂量。对于每种辐射类型，每个剂量组有四只小鼠。在暴露于任何一种辐射的小鼠所采集的骨髓细胞中发现了几种类型的畸变。这些畸变包括交换和断裂（染色单体型和染色体型）。染色体交换包括易位（罗伯逊易位或着丝粒融合、相互易位和不完全易位类型）和双着丝粒。在暴露于56Fe离子或137Csγ射线的小鼠中观察到的任何类型畸变中，未发现特定染色体有非随机参与的证据。在我们的体内研究中使用的辐射剂量范围内，大多数交换是简单的。仅在暴露于1 Gy 56Fe离子或3 Gy 137Csγ射线的小鼠所采集的骨髓细胞中检测到复杂交换，但其频率较低。总体而言，我们的体内数据表明，暴露于56Fe离子或137Csγ射线的小鼠所采集的骨髓细胞中，复杂染色体交换的频率没有显著差异。每种辐射类型均诱导染色体损伤频率（包括异常细胞数量）出现显著的剂量依赖性增加（方差分析，P < 0.01）。根据剂量 - 反应曲线的线性项，在诱导染色体损伤方面，56Fe离子比137Csγ射线有效1.6倍（所有类型的交换）、4.3倍（异常细胞）和4.2倍（染色单体型和染色体型断裂）。
