CHROMOSOMAL TELOMERES IN DROSOPHILA

果蝇的染色体端粒

• 批准号: 3294501
• 负责人: ROBERT W LEVIS
• 金额: $ 17.67万
• 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 1994-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/3294501
• 关键词: DNA; Drosophilidae; chromosome aberrations; chromosome deletion; chromosome translocation; gene duplication; gene expression; genetic library; genetic manipulation; genetic models; in situ hybridization; molecular cloning; nucleic acid probes; plasmids; polymerase chain reaction; protein structure function; southern blotting; telomere

Telomeres are the ends of eukaryotic chromosomes and are thought to be specialized for several vital functions. This application evaluates the hypothesis that Drosophila has telomeres with a structure fundamentally different from that reported for other eukaryotes. Simple-sequence tandem repeats are a ubiquitous feature of the DNA at the chromosomal termini of many phylogenetically diverse eukaryotes, including man. These repeats have been shown to be necessary and sufficient for telomere functions in yeast. A terminus of a Drosophila chromosome has been isolated and found to lack this terminal repeat motif. One of the specific aims of this proposal is to isolate this terminus from other strains of Drosophila to confirm that the first terminus examined is typical and has not lost the normal telomere by mutation. The terminal region will be isolated from recombinant libraries of the genomic DNA of other strains by hybridization with a subterminal unique sequence probe. The Drosophila terminus which has been isolated has a region of complex repetitive sequences, probably including a portion of a retrotransposon, at the end. Complex repeats are common in the subterminal regions of the chromosomes of other eukaryotes, but have no established functions and are thought to be dispensable. In Drosophila, these complex repeats may be providing telomere functions in lieu of conventional telomeric repeats. However, there is a progressive loss of the terminal sequences from the end of this chromosome. A second aim of the proposal is to test the predictions of a hypothesis that the slow terminal loss is balanced by occasional transpositions of retrotransposons to the terminus. In situ hybridization will be used to test whether the putative retrotransposon already isolated from one terminus is often found near other termini. Identification of remnants of other retrotransposons within the complex terminal repeat region is also proposed. This will be done by screening the terminal region DNA clones for sequences conserved among retrotransposon genes encoding reverse transcriptase-related proteins. Furthermore, terminal additions capping terminal deletions will be studied to see whether these involve terminal transpositions of retrotransposons.

端粒是真核生物染色体的末端， 专门用于几个重要功能。 该应用程序评估 果蝇端粒的结构 与其他真核生物报道的有根本不同。 简单序列串联重复序列是DNA的普遍特征， 许多遗传多样的真核生物的染色体末端， 包括人类。这些重复被证明是必要的， 足以在酵母中实现端粒功能。 果蝇的末端 已分离出一条染色体，发现它缺少这种末端重复序列 母题 该提案的具体目标之一是将其隔离 其他果蝇品系的末端，以证实第一个 末端检查是典型的，并没有失去正常的端粒， 突变 将从重组体中分离末端区域， 其它菌株的基因组DNA文库， 亚末端独特序列探针。 已经分离的果蝇末端具有一个区域， 复杂的重复序列，可能包括一部分 反转录转座子在最后。 复杂的重复序列常见于 其他真核生物染色体的亚末端区域，但没有 已建立的功能，并被认为是可扩展的。 在果蝇中， 这些复杂的重复序列可以提供端粒功能， 常规端粒重复序列。 然而，有一个渐进的损失， 这条染色体的末端序列 的第二目的 该提案是为了测试一个假设的预测， 终端损耗通过偶尔的 反转录转座子到末端。 原位杂交将用于 测试假定的反转录转座子是否已经从一个 通常在其他终端附近发现终端。 残余物的识别 在复杂的末端重复区域内的其他反转录转座子的 并提出了 这将通过筛选末端区域DNA来完成 逆转录转座子基因保守序列的克隆 逆转录酶相关蛋白。 此外，终端添加 将研究加帽末端缺失，以确定这些是否涉及 反转录转座子的末端转座。