GENOME REORGANIZATION IN HYPOTRICHOUS CILIATED PROTOZOA

已观察到程序性基因组重排事件 在各种原核生物和真核生物中。在许多 例如，DNA重排被用来控制基因表达， 在脊椎动物免疫系统的发育过程中。在……里面 此外，一些病原微生物利用DNA 重排作为调节其表达的一种手段 表面蛋白从而逃避免疫反应。广泛性 发育中的基因组重排事件，涉及 消除整个染色体或部分染色体，有 也观察到了，但它们的功能尚不清楚。 拟议的研究将检查基因组重组。 下毛纤毛虫的大核发育事件 原生动物Oxytricha nova和Eplotes Crassus。在他们的一生中 循环，这些有机体将它们的染色体的副本 将微核转变为含有线性、基因大小的大核 DNA分子。产生大核的过程 涉及多种类型的重排事件，包括 染色体碎裂、DNA消除、核酸 剪接和DNA序列添加。它的广泛性 重排过程，以及在 实验室，使其成为研究DNA的良好模型系统 真核生物中的重排。 初步研究将利用特征化的重组克隆 大核DNA分子及其微核 前兆分析的时间和顺序的各种 大核发育过程中的重排事件。这些 将对E.Crassus进行研究，它可以用来 生成大量的单元格，同时通过 大核发育，从而提供了阶段性的来源 DNA。更多的研究将定义哪些染色体位置 赋予重排过程特异性。该方法可用于 包括将克隆的DNA分子显微注射到 正在经历大核发育的细胞，随后是 重新分离和分析DNA以检测加工过程。核子 提取液也将从正在发育的细胞中制备 并用于开发两种酶的体外检测系统 催化重排事件或与之相互作用的蛋白质 染色体重排部位。这些研究将提供新的 关于DNA序列和DNA中涉及的蛋白质的信息 重排事件并扩展我们对分子的知识 基因组重组的机制。

Programmed genomic rearrangement events have been observed in a variety of prokaryotic and eukaryotic organisms. In many instances, DNA rearrangement is used to control gene expression, as in the development of the vertebrate immune system. In addition, some pathogenic microorganisms utilize DNA rearrangement as a means of regulating the expression of their surface proteins so as to evade the immune response. Extensive developmental genomic rearrangement events, involving the elimination of whole chromosomes or parts of chromosomes, have also been observed, but their function is unknown. The proposed studies will examine the genome reorganization events of macronuclear development in the hypotrichous ciliated protozoa Oxytricha nova and Euplotes crassus. During their life cycle, these organisms transform a copy of their chromosomal micronucleus into a macronucleus containing linear, gene-sized DNA molecules. The process of generating a macronucleus involves a number of types of rearrangement events including chromosome fragmentation, DNA elimination, nucleic acid splicing, and DNA sequence addition. The extensive nature of the rearrangement process, and the ability to control it in the laboratory, make this a favorable model system for studying DNA rearrangement in eukaryotes. Initial studies will make use of characterized recombinant clones of macronuclear DNA molecules and their micronuclear precursors to analyze the timing and order of the various rearrangement events during macronuclear development. These studies will be performed on E. crassus, which can be used to generate large numbers of cells synchronously proceeding through macronuclear development, thus providing a source of staged DNAs. Additional studies will define chromosomal sites which impart specificity to the rearrangement process. The method to be used involves microinjection of cloned DNA molecules into cells undergoing macronuclear development,followed by reisolation and analysis of the DNA to detect processing. Nuclear extracts will also be prepared from cells undergoing development and used to develop in vitro systems for either detecting enzymes catalyzing rearrangement events or proteins which interact with chromosomal rearrangement sites. These studies will provide new information on DNA sequences and proteins involved in DNA rearrangement events and extend our knowledge of the molecular mechanisms of genome reorganization.