INSTABILITY OF SIMPLE REPETITIVE DNA SEQUENCES IN YEAST

描述（改编自研究者摘要）：所有真核生物 含有简单重复的DNA片段，其中单个碱基或 少量碱基重复多次。 重复束 往往是不稳定的，增加或减少的速度， 远高于对“正常”非重复DNA序列观察到的。 使用在编码序列中插入重复DNA的质粒 选择基因，道不稳定性可以在酵母中测定， 酿酒酵母 拟议的实验检查一些 这种遗传不稳定性的特征。 首先，酵母菌的突变体 将审查增加不稳定程度的问题。 本研究 应该能提供与神经束不稳定机制相关的证据。 第二，改变序列或序列长度的影响， 将检查重复的DNA片段。 三是意志坚定 束长度的改变是否与交换有关。 第四，转基因小鼠在体内的不稳定性， 将开发可监测的重复。 第五，搜索将 用于允许酵母中简单重复序列大量扩增的机制 细胞，因为迄今为止检测到的大多数改变都代表小 变化

DESCRIPTION (adapted from investigator's abstract): All eukaryotes contain tracts of simple repetitive DNA, in which a single base or a small number of bases is repeated multiple times. Repetitive tracts tend to be unstable, increasing or decreasing in size at a rate that is much higher than that observed for "normal" non-repeated DNA sequences. Using plasmids with insertions of repetitive DNA in the coding sequence of selectable genes, tract instability can be assayed in the yeast, Saccharomyces cerevisiae. The proposed experiments examine some properties of this type of genetic instability. First, mutants of yeast that have increased levels of instability will be examined. This study should yield evidence relevant to the mechanisms of tract instability. Second, the effects of altering the sequence or the length of the repetitive DNA tracts will be examined. Third, it will be determined whether alterations in tract length are associated with crossing-over. Fourth, a transgenic mouse in which the in vivo instability of simple repeats can be monitored will be developed. Fifth, a search will be made for mechanisms allowing large expansions of simple repeats in yeast cells since most of the alterations detected to date represent small changes.