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 诱变效应 这是一个多方面的办法， 正在研究的包括诱变、恶性转化、细胞 生存和染色体异常的诱导。该计划已 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。一个特别的重点是归纳 辐射引起的遗传不稳定性，以及同源 重组事件可能在这一过程中起作用。具体目标是：1） 为了鉴定在肿瘤发生过程中被激活或表达的癌基因， 利用变性技术，通过辐射诱发恶性转化 梯度凝胶电泳印迹和差减克隆 代表性差异分析（RDA）技术; 2）检查 全基因组不稳定性在恶性转化中的作用， 寻找同源重组参与的证据， 过程;将在小卫星基因座中检查遗传重排， 以及随机DNA序列。3)为了检测重组的可能性 在测量等位基因间的测定中， 人类细胞中的同源重组， 期间，包括佛波酯肿瘤促进剂TPA和辐射; 4） 为了寻找一组基因组中同时或第二个位点突变的证据， 选择用于突变的细胞中的随机、非选择的微卫星位点 5）为了更好地表征延迟致突变效应， 辐射的分子结构， 突变和鉴定可能被诱导或激活的基因 6）进一步研究突变体克隆的辐射机制， SV 40大T抗原对放射敏感性影响 一组含有单碱基点突变的T抗原突变体， 基因的各种功能结构域的特定序列;和7） 确定特定的mRNA是否在α辐射的细胞中表达 利用差异显示技术， 可以对α辐射做出特定的反应。

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.