STRUCTURE AND MAINTENANCE OF DROSPHILA TELOMERES

果蝇端粒的结构和维持

• 批准号: 2183702
• 负责人: HARALD BIESSMANN
• 金额: $ 21.59万
• 依托单位: UNIVERSITY OF CALIFORNIA-IRVINE
• 依托单位国家: 美国
• 财政年份: 1992
• 资助国家: 美国
• 起止时间: 1992-05-01 至 1996-04-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/2183702
• 关键词: DNA replication; Drosophilidae; RNA directed DNA polymerase; RNase protection assay; SDS polyacrylamide gel electrophoresis; chromatin; chromosome deletion; chromosome walking; gene deletion mutation; genetic library; genetic models; in situ hybridization; molecular cloning; northern blottings; nucleic acid repetitive sequence; nucleic acid sequence; nucleotides; open reading frames; polymerase chain reaction; protein purification; sex chromosomes; southern blotting; telomere; transposon /insertion element

The telomere is a complex structure at the end of linear chromosomes which is specialized for several roles. Telomeres facilitate the complete replication of the ends of the linear chromosomal DNA and thus prevent progressive loss of terminal nucleotides in each round of replication. They also act as "chromosome caps", because the terminal DNA of chromosome ends cannot be linked to other DNA. Such caps appear to be necessary for chromosome stability since non-telomeric ends of broken chromosomes fuse with other broken ends. Telomeres also engage in telomere-to-telomere and telomere-to-nuclear membrane associations which may play a role in nuclear organization. We propose to study the structure of the Drosophila telomere and the healing mechanism of chromosome breaks. We believe that both are intimately related and that by analyzing the behavior of chromosomes that have lost their telomere we will learn a great deal about de novo telomere formation and their maintenance. Based on our previous observations we are presenting a new model of Drosophila telomere elongation by proposing that the two aspects which we have observed at broken chromosome ends, namely progressive loss of nucleotides and transpositions of HeT-A retroposons, may also apply to natural chromosome ends. Thus, continuous loss of terminal nucleotides due to incomplete DNA replication of the ends can be balanced by frequent transposition of HeT-A retroposons to these ends. We will further characterize the recently discovered HeT-A retroposons whose members are associated with natural telomeres and can transpose to broken chromosome ends. Cross-reaction with an oligonucleotide from a highly conserved region of the Drosophila HeT-A element will be performed to screen for related retroposons in other insects and invertebrates. We will also study the molecular basis of the "capping" mechanism of chromosomes. We propose to initiate a molecular analysis of the mutator-2 locus which enabled us to recover terminal chromosome deficiencies. We will thus obtain insights into the mechanisms of chromosome break repair, de novo telomere formation, and chromosome "capping".

端粒是线性染色体末端的复杂结构 它专门用于多种角色。 端粒有利于 线性染色体DNA末端的完全复制，从而 防止每轮末端核苷酸的逐渐丢失 复制。 它们还充当“染色体帽”，因为终端 染色体末端的DNA不能与其他DNA连接。 出现这样的上限 由于非端粒末端是染色体稳定性所必需的 断裂的染色体与其他断裂的末端融合。 端粒也参与 端粒与端粒以及端粒与核膜的关联 可能在核组织中发挥作用。 我们建议研究 果蝇端粒的结构及其愈合机制 染色体断裂。 我们认为两者密切相关并且 通过分析失去端粒的染色体的行为，我们 将学到很多关于端粒从头形成及其原理的知识 维护。 根据我们之前的观察，我们提出了一个新的 果蝇端粒伸长模型提出两个方面 我们在断裂的染色体末端观察到，即渐进性丢失 核苷酸和 HeT-A 反座子的转座，也可能适用于 自然染色体末端。 因此，末端核苷酸的持续丢失 由于末端的 DNA 复制不完整，可以通过频繁地平衡 HeT-A 逆座子转座达到这些目的。 我们将进一步 描述最近发现的 HeT-A 逆转录子的特征，其成员是 与天然端粒相关，可以转座至断裂的染色体 结束。 与高度保守的寡核苷酸发生交叉反应 果蝇 HeT-A 元件区域将进行筛选 其他昆虫和无脊椎动物中的相关反座子。 我们也会 研究染色体“加帽”机制的分子基础。 我们 建议对 mutator-2 基因座进行分子分析 使我们能够恢复染色体末端缺陷。 我们将因此 深入了解染色体断裂修复的机制 端粒形成和染色体“加帽”。