CHROMOSOMAL TELOMERES IN DROSOPHILA

果蝇的染色体端粒

• 批准号: 2179237
• 负责人: ROBERT W LEVIS
• 金额: $ 20.9万
• 依托单位: FRED HUTCHINSON CANCER RESEARCH CENTER
• 依托单位国家: 美国
• 财政年份: 1987
• 资助国家: 美国
• 起止时间: 1987-04-01 至 1998-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/2179237
• 关键词: DNA; Drosophilidae; chromosome aberrations; chromosome deletion; chromosome translocation; gene duplication; gene expression; genetic library; genetic mapping; genetic models; genetic regulatory element; genetic transcription; in situ hybridization; laboratory rabbit; molecular cloning; northern blottings; nucleic acid probes; polymerase chain reaction; protein sequence; protein structure function; southern blotting; telomere; transposon /insertion element

The ends of eukaryotic chromosomes, called telomeres, perform several vital functions. One function is self-maintenance; because loss of DNA from the terminus is inherent in replication, this loss must be counterbalanced by addition of telomeric DNA to the terminus. The long- term goal of the research proposed here is to understand the structure of Drosophila telomeres, how they are maintained, and how they function. It appears that Drosophila telomeres are maintained by a novel mechanism involving the occasional transposition to the terminus of specialized families of non-LTR retrotransposons. Non-LTR retrotransposons, also called LINEs, are a class of mobile elements which is ubiquitous among metazoans and has been implicated in causing mutations in man. Two families of telomere-associated LINEs, HeT-A and TART, have been found in Drosophila. A long-term objective of this project is to determine the basis for the unusual transpositional specificity of these elements. One specific aim proposed in this application is to show that HeT-A and TART elements are at the termini of Drosophila chromosomes by identifying terminal DNA fragments hybridizing with DNA probes for these elements. A second aim is to survey the number, DNA sequence organization, and chromosomal locations of TART elements in D. melanogaster and other Drosophila species. This will be accomplished by genomic Southern blot analysis, in situ hybridization, and DNA cloning. A third aim is to characterize the expression of TART in D. melanogaster. The transcription unit and promoter will be mapped. The tissues and developmental stages in which the transcription and translation products of TART accumulate will also be determined. The fourth aim is to reintroduce a cloned TART element into the germline of D. melanogaster and show that it will transpose to a telomere. This would provide an in vivo transposition assay for future in vitro mutagenesis experiments.

真核生物染色体的末端称为端粒，执行多种功能 重要功能。功能之一是自我维护；因为DNA的丢失 从终点开始是复制所固有的，这种损失必须是 通过在末端添加端粒 DNA 来平衡。长- 这里提出的研究的术语目标是了解 果蝇端粒，它们如何维持以及它们如何发挥作用。它 果蝇端粒似乎是由一种新机制维持的 涉及偶尔换位到专门的终点站 非 LTR 反转录转座子家族。非 LTR 反转录转座子，也 称为 LINE 的一类移动元素，在 后生动物，并与引起人类突变有关。二 端粒相关 LINE 家族、HeT-A 和 TART 已被发现 果蝇。该项目的长期目标是确定 这些元素不寻常的换位特异性的基础。一 本申请提出的具体目的是证明 HeT-A 和 TART 通过识别元件位于果蝇染色体的末端 末端 DNA 片段与这些元件的 DNA 探针杂交。一个 第二个目标是调查数量、DNA 序列组织，以及 黑腹果蝇和其他果蝇中 TART 元件的染色体位置 果蝇种类。这将通过基因组 Southern 印迹来完成 分析、原位杂交和 DNA 克隆。第三个目标是 表征黑腹果蝇中 TART 的表达。转录 单位和启动子将被映射。组织和发育阶段 TART 积累的转录和翻译产物将 也可以确定。第四个目标是重新引入克隆的 TART 元件 进入 D. melanogaster 的种系并表明它将转变成 端粒。这将为未来的体内转座测定提供 体外诱变实验。