CHROMOSOMAL TELOMERES IN DROSOPHILA

真核生物染色体的末端，称为端粒，执行几个 重要功能。一种功能是自我维持；因为DNA的丢失 从末端复制是固有的，这种损失必须是 通过将端粒DNA添加到末端来平衡。长的- 在这里提出的研究的术语目标是理解结构 果蝇端粒，它们是如何维持的，它们是如何发挥作用的。它 果蝇的端粒似乎是由一种新的机制维持的 偶尔涉及到专门化的 非LTR反转录转座子家族。非LTR反转录转座子 称为线路，是一类普遍存在于 后生动物，并已被牵连在导致人类突变。二 端粒相关品系HET-A和START的家族已在 果蝇。这个项目的一个长期目标是确定 这些元件具有不同寻常的转位特异性的基础。一 本申请中提出的具体目标是显示HET-A和START 分子位于果蝇染色体的末端，通过鉴定 末端DNA片段与这些元素的DNA探针杂交。一个 第二个目标是调查数字，DNA序列组织，以及 黑腹金丝猴等的尖酸分子的染色体定位 果蝇物种。这将通过基因组Southern杂交来完成 分析、原位杂交和DNA克隆。第三个目标是 研究了START在黑腹金丝猴中的表达。抄写 单位和启动子将被绘制出来。白纹伊蚊的组织和发育阶段 TART的转录和翻译产品积累的将 也要有决心。第四个目标是重新引入克隆的TART元件 并表明它将转座为一种 端粒。这将为未来的体内转座试验提供一种新的方法 体外诱变实验。

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.