GENOME REORGANIZATION IN HYPOTRICHOUS CILIATED PROTOZOA

尽管一些基因和基因组重排过程已经 在真核生物中定义的，调节这些事件的机制 人们对此了解甚少。我们计划研究广泛的基因组 重组发生在下毛纤毛原虫中的重组过程，如 作为Oxytricha nova和Stylonchia Mytilus，为了扩展我们的知识 真核重排过程以及定义DNA的类型 调节这类事件的序列和酶。在这些生物体中有一个拷贝 的染色体微核基因组转化为大核 含有基因大小的小DNA分子。这种基因组重排 过程发生在生物体生命周期的特定时间，包括 DNA序列消除、序列添加和序列测定的步骤 重新编排。 我们计划研究这种基因组重排过程，通过构建 大核DNA分子的重组DNA克隆及其区域 它们衍生出的微核染色体。这些材料将 以确定保留的DNA序列和 在开发过程中被淘汰。我们还将克隆和刻画 重组过程中产生的中间DNA形式按顺序 确定生产过程中涉及的事件或步骤的顺序 来自微核染色体的基因大小的大核DNA分子。 最后，我们将开发两个系统，使我们能够研究 介导基因组重组的特定DNA序列和酶。在……里面 首先，我们将直接显微注射克隆的微核DNA序列 发展成大核并跟随它们的命运，以便准确地 定义重排过程中涉及的序列。我们的第二个方法将是 建立参与重排的酶的体外检测方法，最终 提纯并描述他们的活动。

Although a number of gene and genome rearrangement processes have been defined in eukaryotic organisms, the mechanisms that mediate these events are poorly understood. We plan to study the extensive genome reorganization process that occurs in hypotrichous ciliated protozoa, such as Oxytricha nova and Stylonychia mytilus, in order to extend our knowledge of eukaryotic rearrangement processes as well as to define the types of DNA sequences and enzymes that mediate such events. In these organisms a copy of the chromosomal micronuclear genome is transformed into a macronucleus containing small gene-size DNA molecules. This genome rearrangement process occurs at a defined time in the organism's life cycle and involves steps of DNA sequence elimination, sequence addition, and sequence rearrangement. We plan to study this genome rearrangement process by constructing recombinant DNA clones of macronuclear DNA molecules and the regions of the micronuclear chromosome from which they are derived. These materials will be characterized in order to define DNA sequences that are retained and eliminated during development. We will also clone and characterize intermediate DNA forms generated during the reorganization process in order to determine the sequence of events or steps involved in producing gene-size macronuclear DNA molecules from micronuclear chromosomes. Finally, we will develop two systems that will allow us to study the particular DNA sequences and enzymes mediating genome reorganization. In the first, we will directly microinject cloned micronuclear DNA sequences into developing macronuclei and follow their fate in order to precisely define sequences involved in rearrangement. Our second approach will be to develop in vitro assays for enzymes involved in rearrangement to ultimately purify and characterize their activities.