TRANSPOSITION AND DNA REPAIR IN DROSOPHILA

目的：果蝇有丝分裂期双链DNA断裂的修复 将对细胞进行遗传分析。 这样的断裂可以由两个 机构的主要类别：重组和末端连接。 这些 不同类别的修复产品的种类有很大不同， 制作。 在每个类中，多个单独的路径被认为是 存在 我们的目标是对这些基因进行基因解剖 机制等 对于每一个主要途径，遗传后果和 将确定修复产品的结构。 审查 这些参数在参与修复的基因座的一系列突变中， 过程将揭示通路的不同以及修复的类型 受到影响的。 方法：切除P转座因子提供了一种有用的方法， 在特定的，已知的，位置产生双链断裂， 基因组 这些切除可以由P转座酶调节。 在 此外，两种位点特异性核酸内切酶HO和I-SceI已被 在果蝇中发挥作用。 这三种方法将用于 在明确定义的条件下在体内产生特异性双链断裂 遗传条件。 利用这些特定地点的断裂进行的一系列测试 将应用于不同的遗传背景，以提供详细的 描述双链断裂修复的后果。 不同的修复途径将通过突变基因来区分 被认为与一种或多种机制有关。 7个遗传位点 参与修复的人被选中，包括各种各样的， 功能协调发展的 两个最近开发的方法将用于获得 突变：第一个在靶向的或附近产生P插入。 第二种方法使用这些插入来获得侧翼缺失 从而破坏基因。 医学意义：DNA修复被认为是维持 基因组的稳定性，特别是在具有复杂基因组的物种中。 许多DNA修复基因中的人类突变，包括人类同源基因 在本研究中的几个位点，导致倾向于 癌 更好地理解这些修复过程可以来自 果蝇和人类一样，有着相对复杂的 基因组和多细胞组织，因此需要高水平的 基因组稳定性 与此同时，果蝇给研究人员提供了 分析多途径修复系统所需的遗传工具。

Goals: The repair of double-stranded DNA breaks in Drosophila mitotic cells will be analyzed genetically. Such breaks can be repaired by two main classes of mechanisms: recombinational and end-joining. These classes differ significantly in the kinds of repair products that are produced. Within each class, multiple individual pathways are thought to exist. The goal is to perform a genetic dissection of these mechanisms. For each major pathway, the genetic consequences and the structure of the repair products will be determined. Examination of these parameters in a series of mutations at loci involved in the repair processes will reveal how the pathways differ and the type of repair that is affected. Approach: Excision of P transposable elements provides a useful way to produce double-strand breaks at specific, known, locations in the genome. These excisions can be regulated by P transposase. In addition, two site-specific endonucleases, HO and I-SceI, have been shown to function in Drosophila. These three methods will be used to generate specific double-strand breaks in vivo under well-defined genetic conditions. A series of tests using these site-specific breaks will be applied in different genetic backgrounds to provide a detailed description of the consequences of double-strand break repair. Different pathways for repair will be distinguished by mutating genes thought to be involved with one or more mechanism. Seven genetic loci involved with repair were selected to include a variety of such functions. Two recently-developed methods will be used to obtain mutations: the first generates P insertions in or near the targeted genes, and the second uses these insertions to obtain flanking deletions which knock out the genes. Medical significance: DNA repair is recognized as crucial to maintaining the stability of the genome, especially in species with complex genomes. Human mutations in many DNA repair genes, including the human homologs of several of the loci in the present study, cause predisposition to cancer. A better understanding of these repair processes can come from studies using Drosophila, which, like humans, has a relatively complex genome and multicellular organization, thus requiring a high level of genomic stability. At the same time, Drosophila gives researchers the genetic tools needed to analyze the multi-pathway repair system.