MECHANISMS OF GENETIC RECOMBINATION

本提案的目的是调查所涉及的事件 基因重组在酵母，酿酒酵母。 我们提出 通过研究一个基因区域来研究这个问题， 高频率减数分裂基因转换。 三个基因接近 染色体I在物理上被定位在彼此的9个碱基内。 的 该地区的遗传距离几乎为15 cM-超过3 乘以预期的遗传距离。 其中一个基因的等位基因， 有20%的基因转换 异常高的重组水平 将通过引入密切的遗传学研究， 在该区域内间隔杂合位点。 杂合位点将 作为相互和非相互重组事件的监视器 在减数分裂的区域内。 在系统地替换DNA之后， 通过基因替换技术，我们将评估该区域内的基因片段， 通过测量改变的细胞中的重组， 地区 人们希望极性和奇偶性的分子基础， 基因转换的性质，将通过这种分析来揭示。 我们计划 调查一个地区的不同监管状态如何影响 同源重组 我们计划研究基因的起源 在突变细胞中不能进行基因转换的重组。 最后，我们将研究DNA自由端附近的重组 在体外修饰的分子，通过测量三个分离， DNA转化后的连锁遗传标记。 人们希望 了解基因重组的确切性质， 真核生物将作为高等生物遗传重组的范例 细胞

The aim of this proposal is to investigate the events that are involved in genetic recombination in the yeast, Saccharomyces cerevisiae. We propose to examine this question by investigating a genetic region that undergoes high frequency meiotic gene conversion. Three genes near the end of chromosome I are physically mapped within 9 kilobases of each other. The genetic distance in this region is almost 15 cM in length - more than three times the expected genetic distance. An allele of one of the genes, exhibits 20% gene conversion. The unusually high levels of recombination shown by this region will be studied genetically by introducing closely spaced heterozygous sites within the region. The heterozygous sites will act as monitors for both reciprocal and non-reciprocal recombination events within the region during meiosis. After systematically replacing DNA segments within this region by gene substitution techniques, we will assess the effect of the substitutions by measuring recombination in the altered region. It is hoped that the molecular basis of polarity and parity, two properties of gene conversion, will be revealed by this analysis. We plan to investigate how different regulatory states of a region affect homologous recombination. We plan to investigate initiation of genetic recombination in mutant cells that fail to undergo gene conversion. Finally, we will investigate recombination near the free ends of DNA molecules that are modified in vitro, by measuring the segregation of three linked genetic markers after DNA transformation. It is hoped that understanding the precise nature of genetic recombination in a simple eukaryote will serve as a paradigm for genetic recombination in higher cells.