BIOLOGICALLY SIGNIFICANT DAMAGE IN DNA

DNA 中具有生物学意义的重大损伤

• 批准号: 2007679
• 负责人: JOHN R WARD
• 金额: $ 24.63万
• 依托单位: UNIVERSITY OF CALIFORNIA, SAN DIEGO
• 依托单位国家: 美国
• 财政年份: 1988
• 资助国家: 美国
• 起止时间: 1988-12-15 至 2001-01-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/2007679
• 关键词: DNA damage; DNA repair; Xenopus oocyte; alpha benzopyrone; benzoates; chemical association; dimer; endonuclease; fluorescent dye /probe; free radical scavengers; gene mutation; histones; hydroxyl radical; ionizing radiation; ionophores; linear energy transfer; nucleic acid structure; plasmids; radiation genetics; radiation sensitivity; relative biological effectiveness; simian virus 40; thiols; virus DNA; virus genetics

It is generally accepted that damage to DNA is the cause of cell death by ionizing radiation. A lesion in the DNA which has particular importance in this respect is the double strand break (DSB). From considerations of the mechanisms of production of DSB it is reasoned that locally multiply damaged sites (LMDS), which include base damages as well as strand breaks, are formed by similar mechanisms. These LMDS could also be biologically significant for cell survival in the presence of efficient DSB repair. Similar arguments can be made for the significance of these lesions for other cellular effects of irradiation - mutation and transformation. There have been no previous studies of the structures of these types of lesion either in cellular DNA or in model systems. Here we propose to study the structures of the LMDS and DSB produced as it would be in a cell. A model system, the SV40 minichromosome irradiated in a simulated cellular environment, will be used for the studies, and the specific benefits of this approach are discussed. The model system has been characterized and validated as representative of the DNA in a mammalian cell and a good understanding of the parameters of radiation damage to these molecules has been attained. The Specific Aims of the proposed work are to describe the details of the structures of the biologically significant LMDS with a view to considering a cell's ability to repair them. There are three major Specific Aims in the project and they are: 1. Determine the relative yields of base damage to strand breaks within the LMDS. 2. Determine the spectrum of sizes of the LMDS in terms of numbers of base pairs. 3. Determine the average number of individually damaged sites per LMDS. All of the information gained from these studies will be significant in considering a cell's response to ionizing radiation. A series of novel assays specific for these purposes has been designed with these goals in mind. Several different radiation sources will be employed for the completion of the studies including gamma-rays, soft X-rays and high LET particles. Additional minor studies with this system include: Confirmation of the mathematical model for the production of DSB by coincident SSB; determination of DNA-histone cross-links; development of a general base damage assay; and, development of general method for assaying LMDS.

人们普遍认为，DNA的损害是细胞死亡的原因 电离辐射。 DNA的病变特别重要 在这方面，是双股断裂（DSB）。 从考虑 DSB的生产机制是有理由局部乘以的 损坏的站点（LMD），其中包括基本损坏和链 断裂是通过类似机制形成的。 这些LMD也可能是 在有效的情况下，生物学对细胞生存具有重要意义 DSB维修。 对于这些的重要性，可以提出类似的论点 辐射突变和其他细胞作用的病变 - 转型。 以前没有关于结构的研究 这些类型的病变要么在细胞DNA或模型系统中。 这里 我们建议研究LMD和DSB产生的结构 会在单元格中。 模型系统，SV40微型粒子体辐照 在模拟的细胞环境中，将用于研究， 讨论了这种方法的具体好处。 模型系统 已被表征并证实为A中DNA的代表 哺乳动物细胞，对辐射参数有很好的理解 这些分子的损害已实现。 特定目标 建议的工作是描述结构的细节 生物学意义的LMD，以考虑细胞的能力 修理它们。 该项目中有三个主要的具体目标 它们是：1。确定基本损伤对链的相对产量 在LMD中断裂。 2。确定LMDS大小的光谱 基对数的术语。 3。确定平均数量 每个LMD的单独损坏的站点。 从中获得的所有信息 这些研究将在考虑细胞对细胞的反应方面具有重要意义 电离辐射。 一系列针对这些目的的新颖测定法 已经牢记了这些目标。 几种不同的辐射 资源将用于完成研究 伽玛射线，软X射线和高颗粒。 其他次要研究 使用此系统包括：确认数学模型 CONIDENT SSB生产DSB； DNA-HISTONE的测定 交联；开发一般基本损害测定法；和发展 测定LMD的一般方法。