The temporal and spatial properties of DNA replication in plants related to DNA damage and mutagenesis is poorly understood. Experiments were carried out to explore the relationships between DNA replication, chromatin structure and DNA damage in nuclei from barley root tips. We quantitavely analysed the topological organisation of replication foci using pulse EdU labelling during the S phase and its relationship with the DNA damage induced by mutagenic treatment with maleic hydrazide (MH), nitroso-N-methyl-urea (MNU) and gamma ray. Treatment with mutagens did not change the characteristic S-phase patterns in the nuclei; however, the frequencies of the S-phase-labelled cells after treatment differed from those observed in the control cells. The analyses of DNA replication in barley nuclei were extended to the micronuclei induced by mutagens. Replication in the chromatin of the micronuclei was rare. The results of simultanous TUNEL reaction to identify cells with DNA strand breaks and the labelling of the S-phase cells with EdU revealed the possibility of DNA replication occurring in damaged nuclei. For the first time, the intensity of EdU fluorescence to study the rate of DNA replication was analysed.

中文翻译：

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在大麦中诱变处理后的 DNA 复制。

与 DNA 损伤和诱变相关的植物 DNA 复制的时空特性知之甚少。进行了实验以探索大麦根尖细胞核中DNA复制、染色质结构和DNA损伤之间的关系。我们在 S 期使用脉冲 EdU 标记定量分析了复制灶的拓扑组织及其与由马来酰肼 (MH)、亚硝基-N-甲基-脲 (MNU) 和伽马射线诱变处理引起的 DNA 损伤的关系。用诱变剂处理没有改变细胞核中特征性的 S 期模式；然而，处理后 S 期标记细胞的频率与在对照细胞中观察到的不同。大麦细胞核中 DNA 复制的分析扩展到诱变剂诱导的微核。微核染色质中的复制很少见。同时进行 TUNEL 反应以识别具有 DNA 链断裂的细胞和用 EdU 标记 S 期细胞的结果揭示了 DNA 复制发生在受损细胞核中的可能性。首次分析了用于研究 DNA 复制速率的 EdU 荧光强度。