X-RAY DAMAGE & REPAIR OF PRIMATE CELL & DNA SEQUENCES

在基底部检查细胞DNA的X射线损伤和修复 获得DNA同源群体所需的序列水平 来自受辐射细胞的序列。我们演示了 这在高重复性成分α研究中的可行性 从照射后的猴CV-L细胞中提取DNA序列。这个 系统正在被用来评估阿尔法修复的时间进程 DNA和咖啡因对修复的影响。 我们现在将研究扩展到驻留在受辐射的 将载体导入宿主细胞。这种方法允许 同质群体的X射线损伤与修复研究 克隆基因。最终，它应该提供宿主细胞的反应- 一种用于检测和评估酶活性的激发系统 单个DNA修复酶和编码的转基因基因 对他们来说。质粒是细胞DNA的替代靶标。 对质粒序列的损伤在转染法之前进行验证； 在未受辐射的细胞中遵循修复的时间进程，从而 避免辐射损伤对细胞功能的干扰。 在宿主细胞重新激活方案中，残留的DNA链和 碱基伤害将在碱基序列水平上进行评分，单位为 修复熟练和修复缺陷的体质(例如，AT和 XP)。 携带x射线损伤的dna序列的质粒的拓扑结构必须 被考虑在内，就像我们关于基因表达的报告一样 氯霉素乙酰转移酶基因在细胞中的编码 PSV2CAT。关于质粒型和质粒型之间关系的信息 现在可以实现特定序列的修复。同舟共济 根据x射线对基因表达失活的数据，我们的研究 用环形等离子体提出为X射线研究提供一个模型 对染色质中DNA的影响，染色质中的DNA也排列在 闭合环路。 导入AT细胞的序列中残留的未修复损伤 特别令人感兴趣是因为某些DNA修复缺陷 据信，在所有死亡的人中，有多达5%的人存在AT 在45岁之前患上癌症。

Examining x-ray damage and repair of cellular DNA at the base sequence level required obtaining homogeneous populations of DNA sequences from the irradiated cells. We demonstrated the feasibility of this in studies on highly repetitive component alpha DNA sequence prepared from irradiated monkey CV-l cells. The system is being used to evaluate the time course of repair of alpha DNA and the influence of caffeine on repair. We now extend the studies to alpha DNA residing in irradiated plasmids transfected into host cells. This approach permits studies on x-ray damage and repair of homogeneous populations cloned genes. Eventually, it should provide a host cell react- ivation system for detecting and evaluating the activity of individual DNA repair enzymes and the transfected genes which code for them. Plasmids serve as surrogate targets for cellular DNA. Damage to plasmid sequences are verified before transfection; the time course of repair is followed, in unirradiated cells, thereby avoiding interference from radiation damage to cell functions. With the host cell reactivation scheme, residual DNA strand and base damage will be scored at the base sequence level in cells of repair proficient and repair deficient constitution (e.g., AT and XP). The topology of plasmids carrying x-ray damaged DNA sequences must be taken into account, as in our report on expression of genes coding for chloramphenicol acetyltransferase in cells transfected with pSV2CAT. Information on the relationship of plasmid form and the repair of specific sequences can now be attained. Together with data on x-ray inactivation of gene expression, the studies we propose with circular plasmids provide a model for studying x-ray effects on DNA in the chromatin, where the DNA is also arranged in closed loops. Residual unrepaired damage in sequences transfected into AT cells are of special interest because certain DNA repair deficiencies in AT are believed to be present in as many as 5% of all persons dying of cancer before age 45 years.