从培养的哺乳动物细胞中提取的染色质的辐射分解：DNA中碱不稳定链损伤的产生。

Radiolysis of chromatin extracted from cultured mammalian cells: production of alkali-labile strand damage in DNA.

作者信息

Mee L K, Adelstein S J, Stein G

出版信息

Int J Radiat Biol Relat Stud Phys Chem Med. 1978 May;33(5):443-55. doi: 10.1080/09553007814550361.

Abstract

Chromatin has been isolated from cultured Chinese-hamster lung fibroblasts as an expanded aqueous gel. The DNA in isolated chromatin has been examined by sedimentation on alkaline sucrose gradients. The average molecular weight of the DNA has been determined to be 50 million. gamma-irradiation of isolated chromatin degrades the DNA to lower molecular weight. The yield of single-strand breaks in the DNA is 0.02 single-strand breaks per krad-10(6) dalton, calculated from a dose-range of &--400 krad and covering a DNA molecular weight range of 2 X 10(7)-1.4 X 10(5). There is a considerable difference in the efficiency of the formation of single-strand breaks in DNA irradiated as isolated chromatin compared with chromatin irradiated in whole cells before isolation. For isolated chromatin, values of 6 dV per break have been calculated compared with about 80 eV per break for chromatin irradiated in whole cells, which suggest a large contribution from indirect action by aqueous radicals in isolated chromatin.

摘要

已从培养的中国仓鼠肺成纤维细胞中分离出染色质，呈膨胀的水凝胶状。通过在碱性蔗糖梯度上进行沉降，对分离出的染色质中的DNA进行了检测。已确定DNA的平均分子量为5000万。对分离出的染色质进行γ射线辐照会使DNA降解为分子量更低的产物。根据&-400 krad的剂量范围以及涵盖2×10⁷-1.4×10⁵的DNA分子量范围计算得出，DNA中单链断裂的产率为每千拉德-10⁶道尔顿0.02个单链断裂。与分离前在完整细胞中辐照的染色质相比，作为分离出的染色质进行辐照时，DNA中单链断裂形成效率存在显著差异。对于分离出的染色质，计算得出每个断裂为6 dV，而对于在完整细胞中辐照的染色质，每个断裂约为80 eV，这表明分离出的染色质中水性自由基的间接作用贡献很大。