Luchnik A N, Hisamutdinov T A, Georgiev G P
Institute of Developmental Biology, USSR Academy of Sciences, Moscow.
Nucleic Acids Res. 1988 Jun 10;16(11):5175-90. doi: 10.1093/nar/16.11.5175.
X irradiation was found to inhibit in vivo transcription in mammalian, yeast, insect and avian cells in a dose-dependent manner. Measurements of DNA nicking indicated that about one DNA single-strand break per estimated DNA loop (domain) length is sufficient to explain the effect. The inhibitory effect was partially reversed by post-irradiation incubation of cells. During such incubation DNA nicking was considerably repaired. The size of transcripts was not changed by irradiation. The in vitro (run on) activity of RNA polymerase in nuclei isolated from irradiated cells also was not altered. The dose-response curves were different in various cells, correlating with the reported unequal average domain size of supercoiled DNA (and also replicon size) in diverse organisms.
人们发现，X射线照射能够以剂量依赖的方式抑制哺乳动物、酵母、昆虫和鸟类细胞中的体内转录。DNA切口测量表明，每一个估计的DNA环（结构域）长度大约有一个DNA单链断裂就足以解释这种效应。细胞在照射后进行孵育，这种抑制效应会部分逆转。在这种孵育过程中，DNA切口得到了相当程度的修复。转录本的大小不受照射影响。从受照射细胞中分离出的细胞核中RNA聚合酶的体外（连续转录）活性也未改变。不同细胞中的剂量反应曲线不同，这与报道的不同生物体中超螺旋DNA的平均结构域大小（以及复制子大小）不相等相关。
