CHEMICAL CARCINOGENS AND FRAMESHIFT MUTATION IN YEAST

将在酿酒酵母中研究移码突变 使用遗传学和生物化学相结合的方法 许多来源的证据 表明原核生物中的移码发生在单调的碱基序列中（GGGG 或AAA）。 我们的证据表明酵母移码抑制因子抑制了 四个基本码字GGGG。 我们将对突变的甘氨酸tRNA进行测序， 抑制菌株，以获得直接证据的分子变化， 移码 此外，这一序列工作应提供重要的证据 非孟德尔决定簇（PSI离子）对甘氨酸tRNA的影响。 的 甘氨酸移码抑制基因将通过常规和非整倍体作图 映射. 第二类ICR可回复突变的抑制因子（其可以 CCCC）将进行生物化学和遗传学分析。 的突变 增加这些移码突变的频率将被表征。 一些 这些可能会影响修复系统和其他诱变剂的渗透性。 酵母中两类新的潜在移码将被分离出来， 表征了 我们将在自发极性HIS 4中寻找移码 变种人 将分离这些突变体的抑制子， 通过双标记实验表征。 实验旨在揭示 ICR-170可逆线粒体（MIT减）突变，试图 描述线粒体遗传系统对以下疾病的易感性： 移码突变 最终，这些研究可能会导致 构建能够检测由以下诱导的移码突变的菌株： 在细胞核和线粒体基因组中的致癌物质。

Frameshift mutagenesis will be studied in the yeast Saccharomyces cerevisiae using a combined genetic and biochemical approach. Evidence from many sources suggests that frameshifts in procaryotes occur in monotonous runs of bases (GGGG or AAA). Our evidence suggests that yeast frameshift suppressors suppress the four base code word GGGG. We will sequence the mutant glycine tRNA in our suppressor strains to obtain direct evidence for the molecular change in the frameshifts. In addition this sequence work should provide important evidence on the effect of the non-Mendelian determinant (PSI ion) on glycine tRNA. The glycine frameshift suppressors will be mapped by conventional and aneuploid mapping. Suppressors of a second class of ICR revertible mutations (which could be CCCC) will be analyzed biochemically and genetically. Mutations which enhance the frequency of these frameshift mutations will be characterized. Some of these may affect repair systems and others the permeability of mutagens. Two new classes of potential frameshifts in yeast will be isolated and characterized. We will search for frameshifts among spontaneous polar his4 mutants. Suppressors of such mutants will be isolated and the tRNAs characterized by double label experiments. Experiments are designed to uncover ICR-170 revertible mitochondrial (MIT minus) mutations in an attempt to characterize the susceptibility of the mitochondrial genetic system to frameshift mutagenesis. Ultimately, these studies could lead to the construction of a strain capable of detecting frameshift mutations induced by carcinogens in both the nuclear and the mitochondrial genomes.