BACKGROUND Environmental risk factors have been shown to alter DNA copy number variations (CNVs). Recently, CNVs have been described to arise after low-dose ionizing radiation in vitro and in vivo. Development of cost- and size-effective laser-driven electron accelerators (LDEAs), capable to deliver high energy beams in pico- or femtosecond durations requires examination of their biological effects. Here we studied in vitro impact of LDEAs radiation on known CNV hotspots in human peripheral blood lymphocytes on single cell level. RESULTS Here CNVs in chromosomal regions 1p31.1, 7q11.22, 9q21.3, 10q21.1 and 16q23.1 earlier reported to be sensitive to ionizing radiation were analyzed using molecular cytogenetics. Irradiation of cells with 0.5, 1.5 and 3.0 Gy significantly increased signal intensities in all analyzed chromosomal regions compared to controls. The latter is suggested to be due to radiation-induced duplication or amplification of CNV stretches. As significantly lower gains in mean fluorescence intensities were observed only for chromosomal locus 1p31.1 (after irradiation with 3.0 Gy variant sensitivites of different loci to LDEA is suggested. Negative correlation was found between fluorescence intensities and chromosome size (r = - 0.783, p < 0.001) in cells exposed to 3.0 Gy irradiation and between fluorescence intensities and gene density (r = - 0.475, p < 0.05) in cells exposed to 0.5 Gy irradiation. CONCLUSIONS In this study we demonstrated that irradiation with laser-driven electron bunches can induce molecular-cytogenetically visible CNVs in human blood leukocytes in vitro. These CNVs occur most likely due to duplications or amplification and tend to inversely correlate with chromosome size and gene density. CNVs can last in cell population as stable chromosomal changes for several days after radiation exposure; therefore this endpoint can be used for characterization of genetic effects of accelerated electrons. These findings should be complemented with other studies and implementation of more sophisticated approaches for CNVs analysis.

中文翻译：

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体外人类白细胞超短电子束辐射诱导的拷贝数变异分析。

背景技术环境风险因素已被证明会改变DNA拷贝数变异(CNV)。最近，CNV 被描述为在体外和体内低剂量电离辐射后出现。开发具有成本效益和尺寸效益的激光驱动电子加速器（LDEA），能够在皮秒或飞秒持续时间内提供高能光束，需要检查其生物效应。在这里，我们在单细胞水平上研究了 LDEA 辐射对人外周血淋巴细胞中已知 CNV 热点的体外影响。结果 这里使用分子细胞遗传学分析了先前报道对电离辐射敏感的染色体区域 1p31.1、7q11.22、9q21.3、10q21.1 和 16q23.1 中的 CNV。与对照相比，用 0.5、1.5 和 3.0 Gy 照射细胞，所有分析的染色体区域的信号强度均显着增加。后者被认为是由于辐射引起的 CNV 延伸的复制或放大所致。由于仅在染色体位点 1p31.1 上观察到平均荧光强度显着降低（建议用 3.0 Gy 变异照射后，不同位点对 LDEA 敏感）。在荧光强度和染色体大小之间发现负相关（r = - 0.783，p < 0.001) 在暴露于 3.0 Gy 辐射的细胞中以及在暴露于 0.5 Gy 辐射的细胞中荧光强度和基因密度之间 (r = - 0.475, p < 0.05)。结论 在这项研究中，我们证明激光驱动电子束的辐射可以在体外诱导人类血液白细胞中分子细胞遗传学上可见的 CNV。这些 CNV 的发生最有可能是由于重复或扩增，并且往往与染色体大小和基因密度成反比。CNV 可以在辐射后作为稳定的染色体变化在细胞群中持续数天暴露；因此该终点可用于表征加速电子的遗传效应。这些发现应与其他研究和更复杂的 CNV 分析方法的实施相补充。