Lehman A R, Stevens S
Biochim Biophys Acta. 1977 Jan 3;474(1):49-60. doi: 10.1016/0005-2787(77)90213-1.
The production and repair of double strand breaks induced by gamma-rays in the DNA of human fibroblasts have been measured by sedimentation in sucrose radients under non-denaturing conditions. Unirradiated DNA formed a rapidly sedimenting gel. Low doses of radiation released freely sedimenting DNA molecules from this gel. Higher doses reduced the rate of sedimentation of the free DNA due to the introduction of double strand breaks. The breakage efficiency was 1 break/1.3 X 10(10) daltons of DNA/krad. Postirradiation incubation after a high dose of radiation resulted in an increase in molecular weight of the free DNA molecules, and after a low dose the rapidly-sedimenting gel was reformed. The data suggest that double strand breaks are repaired in human fibroblasts. No significant differences were found between fibroblasts from two normal donors and four patients with the radiosensitive disorder, ataxia telangiectasia, in either the production or repair of double strand breaks.
在非变性条件下，通过蔗糖梯度沉降法测量了γ射线在人成纤维细胞DNA中诱导产生的双链断裂及其修复情况。未受辐射的DNA形成快速沉降的凝胶。低剂量辐射会使这种凝胶释放出自由沉降的DNA分子。高剂量辐射由于引入双链断裂而降低了自由DNA的沉降速率。断裂效率为每千拉德每1.3×10¹⁰道尔顿DNA产生1个双链断裂。高剂量辐射后进行辐照后孵育会导致自由DNA分子分子量增加，低剂量辐射后则会重新形成快速沉降的凝胶。数据表明人成纤维细胞中的双链断裂能够得到修复。在双链断裂的产生或修复方面，两名正常供体的成纤维细胞与四名患有辐射敏感疾病——共济失调毛细血管扩张症的患者的成纤维细胞之间未发现显著差异。
