STIMULATION OF CHROMOSOME PAIRING AND EXCHANGE BY RDNA

RDNA 刺激染色体配对和交换

• 批准号: 3298078
• 负责人: Bruce D. McKEE
• 金额: $ 10.41万
• 依托单位: UNIVERSITY OF TENNESSEE KNOXVILLE
• 依托单位国家: 美国
• 财政年份: 1990
• 资助国家: 美国
• 起止时间: 1990-07-01 至 1993-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/3298078
• 关键词: DNA binding protein; Drosophilidae; alleles; chromosome aberrations; cytogenetics; gene conversion; gene expression; genes; genetic manipulation; genetic mapping; genetic recombination; genetic transcription; immunoelectrophoresis; meiosis; microinjections; molecular cloning; molecular genetics; natural gene amplification; nucleic acid hybridization; nucleic acid probes; nucleic acid sequence; radionuclides; ribosomal DNA; sex chromosomes; transposon /insertion element

The objectives are to analyze the role of rDNA in stimulation of asynoptonemal X:Y pairing and to explore the maintenance of rDNA sequence homogeneity through non-allelic recombination in Drosophila. The experiments are motivated in part by the observation, described in Preliminary Studies, that a cloned transformed rDNA cistron stimulates X:Y pairing when located at a euchromatic site on a pairing deficient X chromosome but not when located on an autosome. Cloned rDNA cistrons transformed into the germ line via P-element vectors will be a) remobilized to obtain new X-linked insertions, and b) destabilized to obtain overlapping internal deletions, using a high efficiency hybrid dysgenesis method. The resulting variants will be mapped and analyzed at the molecular level and used to: 1) assess the relative importance of DNA homology versus gene expression in promotion of X:Y pairing by comparing rDNA sequence requirements for pairing stimulation, transcription, nucleolus formation, and ribosome assembly. 2) test for position and copy number effects on rDNA stimulation of X:Y pairing and rDNA expression. 3) determine the rate and mechanism of rDNA recombination by screening for exchanges and conversions between allelic and non- allelic euchromatic rDNA cistrons. 4) test for magnification (heritable amplification triggered by partial rDNA deficiency) of isolated euchromatic cistrons 5) assess the relative importance of homology versus expression in recombination and magnification by identifying sequence requirements via deletion mapping. In addition, clones of ribosomal insertion sequences will be tested by P-element transformation for effects on X:Y pairing. This research has possible significance for human health. Participation of nucleoli in meiotic chromosome pairing has been linked to non-homologous segregation of nucleolus organizer- containing chromosomes, leading to nondisjunction and Down's syndrome. In addition, non-allelic homologous recombination between dispersed repeated genes is a likely cause of chromosome rearrangements responsible for birth defects and cancer.

目的是分析 rDNA 在刺激 异视 X:Y 配对并探索维护 通过非等位基因重组实现 rDNA 序列同质性 果蝇。 这些实验的部分动机是 初步研究中描述的观察表明，克隆 转化的 rDNA 顺反子在位于 配对缺陷 X 染色体上的常染色质位点，但不是 当位于常染色体上时。 克隆的 rDNA 顺反子转化 通过 P 元素载体进入种系将 a) 重新动员 获得新的 X 连锁插入，并且 b) 去稳定以获得 重叠内部删除，使用高效混合 发育不全法。 由此产生的变体将被映射并 在分子水平上进行分析并用于： 1) 评估DNA同源性与基因的相对重要性 通过比较 rDNA 促进 X:Y 配对的表达 配对刺激、转录的序列要求， 核仁形成和核糖体组装。 2) 测试位置和拷贝数对rDNA刺激的影响 X:Y 配对和 rDNA 表达。 3)确定rDNA重组的速率和机制 筛选等位基因和非等位基因之间的交换和转化 等位基因常染色 rDNA 顺反子。 4) 放大倍数测试（由以下因素触发的遗传放大倍数） 分离的常染色顺反子的部分rDNA缺陷） 5) 评估同源性与表达的相对重要性 通过识别序列进行重组和放大 通过删除映射的要求。 此外，还将测试核糖体插入序列的克隆 通过 P 元素变换来了解对 X:Y 配对的影响。 这项研究对人类健康可能具有重要意义。 核仁参与减数分裂染色体配对 与核仁组织者的非同源分离有关- 含有染色体，导致不分离和唐氏综合症 综合症。 此外，非等位基因同源重组 分散的重复基因之间可能是染色体异常的原因 重组导致出生缺陷和癌症。