CHROMOSOMAL TELOMERES IN DROSOPHILA

果蝇的染色体端粒

• 批准号: 3294500
• 负责人: ROBERT W LEVIS
• 金额: $ 16.99万
• 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/3294500
• 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.

端粒是真核细胞染色体的末端，被认为是 要专门从事几项重要的工作。此应用程序评估 果蝇有结构端粒的假说 从根本上不同于其他真核生物的报道。 简单序列串联重复序列是DNA的一个普遍特征 许多系统发育不同的真核生物的染色体末端， 包括人类。事实证明，这些重复是必要的，而且 足以在酵母中发挥端粒功能。果蝇的终结点 染色体已被分离，并发现缺少该末端重复序列 Motif。这项提议的具体目的之一就是隔离这种 从其他果蝇品系的末端确认第一个 被检查的末端是典型的，没有丢失正常的端粒。 突变。末端区域将从重组 其他菌株基因组DNA文库的构建 子终端唯一序列探针。 已分离的果蝇终末有一个区域 复杂的重复序列，可能包括 反转录转座子，在最后。复杂的重复是常见的 其他真核生物染色体的亚端区，但没有 既定的职能，被认为是可有可无的。在果蝇身上， 这些复杂的重复序列可能正在提供端粒功能，以代替 传统的端粒重复序列。然而，有一个渐进的损失 这条染色体末端的末端序列。第二个目标是 这项提议是为了测试一个假设的预测，即缓慢的 端子损耗通过偶尔的换位来平衡 到末端的反转录转座子。将使用原位杂交技术 测试假定的反转录转座子是否已经从一个 终点站经常出现在其他终点站附近。残留物的鉴定 在复杂末端重复区域内的其他反转录转座子的 也提出了。这将通过筛选末端区域DNA来完成 反转录转座子基因间保守序列的克隆 逆转录酶相关蛋白。此外，端子添加 将研究封顶终端删除，以确定这些删除是否涉及 反转录转座子的末端换位。