The yield and repair of x-ray-induced single-strand breaks in the DNA of Escherichia coli K-12 cells.
The yield and repair of x-ray-induced single-strand breaks in the DNA of Escherichia coli K-12 cells.
复制标题
X 射线诱导的大肠杆菌 K-12 细胞 DNA 单链断裂的产量和修复。
作者：
D. A. Youngs;K. Smith
用碱性蔗糖梯度法测定了经好氧x射线照射后，大肠杆菌细胞染色体DNA单链断裂的产率。使用的实验条件避免了离心速度对DNA沉淀的影响，并允许发生最小或完全的酶修复。结果证实了本实验室早期报告中的定性结论，但表明DNA链断裂的程度先前被低估了3.4至7.6倍，这取决于所使用的菌株和修复条件。简要讨论了用碱性蔗糖梯度法测定DNA单链断裂的技术难点和解释困难。在本实验中，DNA单链断裂的初始产量为32.4/基因组kRad/sup-1/(9.0 eV/Break)。
The yield of single-strand breaks present in chromosomal DNA of Escherichia coli cells after aerobic x irradiation was determined using alkaline sucrose gradient techniques. Experimental conditions were used that avoided a centrifugation speed dependence effect on DNA sedimentation, and allowed either minimal or complete enzymatic repair to occur. The results confirm the qualitative conclusions made in earlier reports from this laboratory, but indicate that the extent of DNA strand breakage was previously underestimated by factors of 3.4 to 7.6, depending on the strain and repair conditions used. Technical and interpretive difficulties in the measurement of DNA single-strand breakage using alkaline sucrose gradient techniques are discussed briefly. In the present experiments, the initial yield of DNA single-strand breaks was found to be 32.4/genome krad/sup -1/ (9.0 eV/break).