STUDIES ON THE GENETIC ORGANIZATION OF TETRAHYMENA

长期目标包括：(1)生发基因图谱和 嗜热四膜虫高度分化的体细胞核 可以研究分化的机制，(2)详细了解 包括影响减数分裂的环境和遗传因素 染色体配对和重组；(3)涉及的遗传因素 在核糖体的生物合成中。所有拟议的研究都利用了 将生发和躯体功能分离到两个不同的核中 四膜虫。具体目标包括：(1)分离缺失的菌株 染色体的臂，并包含染色体臂的新的联结。 这将通过使用复杂的、多个单体的杂交来完成。这个 交叉将在阻止新的生产的情况下进行 体细胞核，因此允许细胞的有效恢复 无性体生发核。(2)建立基于遗传图谱的遗传图谱 有丝分裂重组。这将通过搜索诱导式 特定标记的纯合性。这是必要的，因为减数分裂 重组过于活跃，无法在染色体上定位基因。 紫外线辐射对突变体影响的测量比较 将进行形成和有丝分裂重组。(3)研究 核糖体RNA(RDNA)编码基因的减数分裂重组。 这些研究利用了rDNA的单拷贝组织 生发核。耐药突变和影响核糖体的突变 确认将被隔离。RDNA的突变将通过以下方式确定 与携带有扭曲其扩增的基因的菌株杂交 体细胞核，并将通过In定位到特定的核糖体亚基 体外试验。它们将通过DNA序列分析进行精确定位。特定的 这种基因的突变组合将被用来测量 在对照细胞中减数分裂重组的数量，然后在 不寻常的环境和携带不寻常的核型(单体和 虚无主义经济学)。这项研究应提供详细信息，说明 环境和基因可以影响减数分裂的各个方面。(4)改善 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。

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.