Institute of Genetics, Academy of Sciences, Sofia, Bulgaria.
Theor Appl Genet. 1982 Jun;63(2):161-7. doi: 10.1007/BF00303701.
A reconstructed karyotype of barley with all chromosomes interdistinguishable was treated with hydroxyurea (HU) and Actinomycin D (Act D). The distribution pattern of chromatid aberrations after treatment with HU alone is characterized by a marked preferential involvement in chromatid translocations of segments 36 (NOR of satellite chromosome 6) and 43 (NOR of satellite chromosome 7). Act D applied at the low concentration of 0.05 μg/ml (4.10(-8) M) before HU treatment, or combined with HU, was found to cause an apparent decrease of HU-induced aberration frequencies in NORs. The exchanges in both segments proved to be approximately a half lower after Act D application when compared to the respective controls (treatment with HU alone). A recovery period of 5 h between the prolonged pretreatment with Act D (15 h) and the HU treatment eliminated the effect of the drug. The possible dependence of mutation induction upon the transcriptional activity of rDNA in NORs after Act D application is discussed.
经羟基脲（HU）和放线菌素 D（Act D）处理后，大麦的所有染色体均可区分的重构核型。单独用 HU 处理后，染色单体畸变的分布模式的特点是 36 号染色体片段（卫星染色体 6 的 NOR）和 43 号染色体片段（卫星染色体 7 的 NOR）的染色单体易位明显优先受累。在 HU 处理之前，用低浓度的 0.05μg/ml（4.10(-8) M）的 Act D 处理，或与 HU 联合应用，发现 HU 诱导的 NOR 中的畸变频率明显降低。与各自的对照（单独用 HU 处理）相比，应用 Act D 后两个片段中的交换大约降低了一半。在 Act D 的长时间预处理（15 小时）和 HU 处理之间延长 5 小时的恢复期消除了药物的作用。讨论了 Act D 处理后，rDNA 在 NOR 中的转录活性对突变诱导的可能依赖性。
