STUDIES ON THE GENETIC ORGANIZATION OF TETRAHYMENA

四膜虫遗传组织的研究

• 批准号: 3275091
• 负责人: PETER J. BRUNS
• 金额: $ 19.87万
• 依托单位: CORNELL UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 1980
• 资助国家: 美国
• 起止时间: 1980-04-01 至 1990-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/3275091
• 关键词: Tetrahymena; cell differentiation; cell nucleus; cell sorting; chromosome deletion; chromosomes; cryoscience; cytogenetics; drug resistance; gene expression; gene mutation; genetic manipulation; genetic mapping; genetic markers; genetic recombination; genetic strain; linkage mapping; meiosis; nondisjunction; nucleic acid sequence; particle counter; radiation genetics; radiotracer; reagent /indicator; ribosomal DNA; ribosomes; structural genes; temperature sensitive mutant; ultraviolet radiation

The long term objectives include (1) a mapping of genes in the germinal and highly differentiated somatic nuclei of Tetrahymena thermophila so that mechanisms in differentiation can be studied, (2) a detailed understanding of meiosis, including environmental and genetic factors that influence chromosome pairing and recombination, and (3) the genetic factors involved in ribosomes biosynthesis. All of the proposed studies exploit the separation of germinal and somatic functions into two different nuclei in Tetrahymena. Specific aims include: (1) The isolation of strains missing arms of chromosomes, and containing novel associations of chromosome arms. This will be done by crosses using complex, multiple monosomics. The crosses will be done in circumstances that prevent the production of new somatic nuclei, and therefore allow the viable recovery of cells with nullisomic germinal nuclei. (2) The creation of a genetic map based on mitotic recombination. This will be done by searching for induced homozygosity of specific markers. It is necessary since meiotic recombination is too active to allow mapping of genes on chromosomes. Measurements comparing the effect of ultra violet radiation on mutant formation and mitotic recombination will be performed. (3) A study of meiotic recombination in the gene coding for the ribosomal RNA (the rDNA). These studies exploit the single copy organization of the rDNA in the germinal nucleus. Drug resistant mutants, and mutations effecting ribosome confirmation will be isolated. Mutations in the rDNA will be identified by crosses with strains carrying a gene that distorts its amplicication in the somatic nucleus, and will be localized to specific ribosomal subunits by in vitro testing. They will be pinpointed by DNA sequence analysis. Specific combinations of mutations in this gene will be used to measure the exact amount of meiotic recombination in control cells, and then in cells in unusual environments and carrying unusual karyotypes (monosomics and nullisomics). This study should provide detailed information on how environment and genotype can influence aspects of meiosis. (4) Improved methods of freezing and storage of these complex cells will be developed based on the effects of prolonged starvation.

长期目标包括 (1) 绘制生发和胚胎中的基因图谱。 嗜热四膜虫的体细胞核高度分化， 可以研究分化机制，（2）详细了解 减数分裂，包括影响减数分裂的环境和遗传因素 染色体配对和重组，以及（3）涉及的遗传因素 在核糖体生物合成中。 所有拟议的研究都利用了 将生发和体细胞功能分离成两个不同的细胞核 四膜虫。 具体目标包括： (1) 分离缺失菌株 染色体臂，并包含染色体臂的新关联。 这将通过使用复杂的、多个单体的杂交来完成。 这 杂交将在阻止产生新物种的情况下进行 体细胞核，因此允许细胞的可行恢复 无效生发核。 (2) 遗传图谱的构建 有丝分裂重组。 这将通过搜索诱导来完成 特定标记的纯合性。 自减数分裂以来这是必要的 重组过于活跃，无法在染色体上绘制基因图谱。 测量比较紫外线辐射对突变体的影响 将进行形成和有丝分裂重组。 (3) 研究 核糖体 RNA (rDNA) 基因编码中的减数分裂重组。 这些研究利用了 rDNA 的单拷贝组织 生发核。 耐药突变体和影响核糖体的突变 确认将被隔离。 rDNA 中的突变将通过以下方式鉴定 与携带扭曲其扩增的基因的菌株杂交 体细胞核，并且将通过 in 定位到特定的核糖体亚基 体外测试。 他们将通过 DNA 序列分析来确定。 具体的 该基因突变的组合将用于测量准确的 对照细胞中的减数分裂重组量，然后是细胞中的减数分裂重组量 不寻常的环境和携带不寻常的核型（单体和 无效组学）。 这项研究应提供有关如何 环境和基因型可以影响减数分裂的各个方面。 (4) 改进 将开发冷冻和储存这些复杂细胞的方法 基于长期饥饿的影响。