Barenfel'd L S, Bil'din V N, Pleskach N M, Prokof'eva V V
Tsitologiia. 1985 May;27(5):582-6.
DNA synthesis after gamma-irradiation was analysed either by direct assay of the amount of 3H-Td incorporated into DNA of fibroblasts derived from normal donor and from a patient with Down's syndrome, or by analysis of the steady-state distribution of 3H-DNA in alkaline sucrose gradients. Doses of gamma-radiation that markedly inhibited the rate of DNA synthesis in normal human cells caused almost no inhibition in fibroblasts of the patient with Down's syndrome. The radioresistant DNA synthesis in cells of this patient was mainly due to a much less inhibition of replicon initiation than that in normal cells. Thus, in the case of Down's syndrome, the cells fail to go through the delays during which DNA lesions can be repaired, unlike the situation being the case in normal cells.
通过直接测定掺入来自正常供体和成唐氏综合征患者的成纤维细胞DNA中的3H-Td量，或通过分析碱性蔗糖梯度中3H-DNA的稳态分布，来分析γ射线照射后的DNA合成。显著抑制正常人细胞DNA合成速率的γ射线剂量，对唐氏综合征患者的成纤维细胞几乎没有抑制作用。该患者细胞中抗辐射的DNA合成主要是由于复制子起始受到的抑制比正常细胞少得多。因此，在唐氏综合征的情况下，细胞不像正常细胞那样会经历可修复DNA损伤的延迟阶段。
