ISOLATION OF RADIATION SENSITIVE MAMMALIAN CELL

该项目的长期目标是提供一个 对辐射修复机制的认识 诱导哺乳动物细胞DNA损伤以及这些过程是如何 可能参与了细胞对电离辐射的存活。这个 这一具体提案的目标是从基因上分离出一系列 与中国仓鼠卵巢细胞系不同的突变体 对电离辐射的杀戮异常敏感 描述他们对这种和其他类型的DNA的敏感性 破坏性因素。使用尼龙布复制电镀和暗场- 摄影，我们将继续分离一系列伽马射线- 敏感的突变体。在先前分离的突变体(XR-1)中 G1期对伽玛射线敏感和修复不足 细胞周期但具有正常抵抗和修复能力的晚期-S， 我们将分离出一个在G1和G1期都敏感的双重突变体 美国其他对伽马射线致死敏感的突变体 细胞周期的特定阶段将被分离出来 温度敏感型细胞周期突变体，或通过给予周期性 伽马射线的剂量。以XR-1细胞作为阳性对照， 我们将调查开发方法的可能性，以便 伽玛射线修复缺陷突变体的直接分离 诱导的DNA链断裂。随着新的突变体的分离，他们 将通过融合分成不同的互补组 不同对辐射敏感的突变体和测试 由此产生的杂交物具有抗辐射能力。突变体属于 将对不同的互补组进行伽马检查 在整个细胞周期中对射线的敏感性决定是否 它们在细胞的特定阶段异常敏感- 周而复始。突变体对其他类型DNA损伤的敏感性 特工也将接受检查。我们相信，一批 基因上截然不同的辐射敏感突变体将被证明是 理解细胞过程的无价工具 对电离辐射负责生存。

The long-term objective of this project is to provide an understanding of mechanisms involved in the repair of radiation induced DNA lesions in mammalian cells and how these processes may be involved in cellular survival to ionizing radiation. The goal of this specific proposal is to isolate a series of genetically distinct mutants from the Chinese hamster ovary cell line which are abnormally sensitive to killing by ionizing radiation and to characterize their sensitivity to this and other types of DNA damaging agents. Using nylon cloth replica plating and darkfield- photography, we will continue to isolate a series of gamma-ray- sensitive mutants. In a previously isolated mutant (XR-1) which is gamma-ray sensitive and repair deficient in the G1 phase of the cell-cycle but has normal resistance and repair capacity in late-S, we will isolate a double mutant which is sensitive in both G1 and S. Other mutants which are sensitive to killing by gamma-ray at specific phases of the cell-cycle will be isolated using temperature sensitive cell-cycle mutants, or by giving periodic doses of gamma-rays. Using the XR-1 cell as a positive control, we will investigate the possibility of developing methods for the direct isolation of mutants defective in the repair of gamma-ray- induced DNA strand breaks. As new mutants are isolated, they will be grouped into separate complementation groups by fusing different pairs of radiation sensitive mutants and testing the resulting hybrids for radiation resistance. Mutants belonging to different complementation groups will be examined for gamma ray sensitivity throughout the cell-cycle to determine whether they are unusually sensitive in a particular phase of the cell- cycle. The mutants' sensitivity to other types of DNA damaging agents will also be examined. We believe that a collection of genetically distinct radiation-sensitive mutants will prove to be invaluable tools in understanding the cellular processes responsible for survival to ionizing radiation.