EFFECTS OF RADIATION ON MAMMALIAN CELLS

这项研究计划的长期目标是获得知识 关于哺乳动物细胞对 电离辐射，特别是其致癌和 诱变效果。该方法是一种多方面的方法，端点 正在调查的包括突变、恶性转化、细胞 存活和诱发染色体异常。该计划有 进一步界定低水平辐射风险的总体目的 通过更好地了解细胞和分子 其影响的机制。一个特别的重点是诱导 辐射引起的遗传不稳定性以及同源基因的作用 重组事件可能会在这一过程中发挥作用。具体目标是：1) 鉴定在癌变过程中被激活或表达的癌基因 辐射诱发的恶性转化，利用变性 梯度凝胶电泳法与差减克隆 代表性差异分析(RDA)技术；2)检验 尤其是全基因组的不稳定性在恶性转化中的作用 寻找同源重组参与这一过程的证据 过程；基因重排将在小卫星座位上进行检查，如 以及随机的DNA序列。3)检测重组潜能 一种测定等位基因的几种试剂 在先前的资助期间，人类细胞中的同源重组发生了 期间，包括佛波酯类肿瘤促进剂TPA和放射；4) 寻找一组基因重合或第二个位点突变的证据 选择突变的细胞中的随机、未选择的微卫星座位 在tk基因座；5)更好地表征延迟诱变效应 通过研究后生植物的分子结构来研究辐射 可能诱发或激活的基因突变和鉴定(S) 诱变子克隆中的辐射；6)进一步研究 SV40大T抗原对放射敏感性的影响 包含单碱基点突变的T抗原突变组 该基因的各种功能结构域的特定序列；以及7)至 确定特定的mRNAs是否在阿尔法辐射的细胞中表达 通过使用差异显示技术，为了识别基因 这可能是专门针对阿尔法辐射而开启的。

The long-term goal of this research program is to gain knowledge concerning the mechanisms involved in the response of mammalian cells to ionizing radiation, with particular reference to its carcinogenic and mutagenic effects. The approach is a multi-faceted one, and the endpoints under investigation include mutagenesis, malignant transformation, cell survival and the induction of chromosomal abnormalities. The program has the overall purpose of further defining the risks of low-level radiation exposure by gaining a better understanding of the cellular and molecular mechanisms for its effects. A particular focus is on the induction of genetic instability by radiation, and the role that homologous recombinational events may play in this process. The Specific Aims are: 1) To identity oncogenes activated or expressed during the process of malignant transformation induced by radiation, by use of denaturing gradient gel electrophoresis blots and subtraction cloning by the representational differences analysis (RDA) technique; 2) To examine the role of genome-wide instability in malignant transformation, in particular to seek evidence for the involvement of homologous recombination in this process; genetic rearrangements will be examined in minisatellite loci as well as random DNA sequences. 3) To examine the recombinogenic potential of several classes of agents in an assay for measuring interallelic homologous recombination in human cells developed during the prior grant period, including the phorbol ester tumor promoter TPA and radiation; 4) To seek evidence for coincident or second site mutations in a group of random, non-selected microsatellite loci in cells selected for mutations at the tk locus; 5) To better characterize the delayed mutagenic effects of radiation by examining the molecular structure of late-arising mutations and identifying the gene(s) that may be induced or activated by radiation in mutator clones; 6) To examine further the mechanism for the effect of SV40 large T antigen on radiosensitivity, by use of a large panel of T-antigen mutants containing single-base point mutations in specific sequences of the various functional domain of the gene; and 7) To determine whether specific mRNAs are expressed in alpha irradiated cells by use of the differential display technique, in order to identity genes that may be turned on in response specifically to alpha radiation.