ISOLATION OF RADIATION SENSITIVE MAMMALIAN CELL

该项目的长期目标是提供一个 了解辐射修复的机制 在哺乳动物细胞中诱导DNA损伤，以及这些过程如何 可能与细胞在电离辐射下的存活有关。 的 这项具体建议的目标是分离一系列基因 来自中国仓鼠卵巢细胞系的不同突变体， 对电离辐射杀伤异常敏感， 描述它们对这种和其他类型DNA的敏感性 破坏剂。 使用尼龙布复制电镀和暗场- 摄影，我们将继续分离出一系列的伽马射线， 敏感的突变体 在先前分离的突变体（XR-1）中， γ射线敏感和修复缺陷的G1期， 细胞周期，但有正常的阻力和修复能力， 我们将分离出一个双突变体，它在G1和 S. 其他对伽马射线杀伤敏感的突变体， 细胞周期的特定阶段将使用 温度敏感的细胞周期突变体，或通过给予周期性 剂量的伽马射线 使用XR-1细胞作为阳性对照， 我们将研究开发方法的可能性 直接分离伽马射线修复缺陷突变体， 诱导DNA链断裂。 当新的突变体被分离出来时， 将通过融合而被分组为单独的互补组， 不同对辐射敏感的突变体和测试 从而产生耐辐射的杂交体。 突变体属于 将检查不同互补组的γ 在整个细胞周期的射线敏感性，以确定是否 它们在细胞的特定阶段异常敏感 周期 突变体对其他类型DNA损伤的敏感性 代理商也将接受审查。 我们相信， 遗传上不同的辐射敏感突变体将被证明是 了解细胞过程的宝贵工具 负责电离辐射的生存。

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.