GENE AMPLIFICATION AND ELIMINATION IN TETRAHYMENA

我建议研究各种发展过程，它们改变了 模式系统四膜虫中真核基因组的组织。脱氧核糖核酸 消除、rDNA扩增和染色体断裂都已被证明 发生在这种有机体中，并将进行详细的研究。RDNA存在 在这种有机体的染色体中作为单拷贝序列。在.期间 在发育过程中，染色体断裂发生在该基因附近，rDNA 从染色体上释放出来进行扩增。侧翼的一部分 在这个过程中，DNA也会被消除。我们将分离rDNA和 从巨核和微核克隆和克隆的侧翼序列 确定这些连接中的核苷酸序列。改建 在大核发育过程中也将通过以下方式进行研究 杂交。这种方法应该揭示出 参与消除、放大和破坏，而分子 这些过程发生的机制。消除DNA和 染色体的断裂也发生在基因组的其他位置，并可能 与简单重复的六核苷酸CCCCAA相关。C4A2 重复序列和微核特定序列将被分离在一起 通过克隆将它们的侧翼序列从两个核中克隆出来。侧翼 序列将被用来确定淘汰的性质和作用 的C4A2在这些过程中重复。这项研究应该会对我们有所帮助 了解哪些特定的核苷酸序列涉及 改变，以及整个基因组可能如何重组，也许还有 这些事件可能如何与人的正常发育过程有关 真核生物。

I propose to study the various developmental processes which alter the organization of an eukaryotic genome in the model system Tetrahymena. DNA elimination, rDNA amplification and chromosome breakage have all been shown to occur in this organism, and will be studied in detail. The rDNA exist as a single copy sequence in the chromosome of this organism. During development, chromosome breakage occurs near this gene and the rDNA is released from the chromosome for amplification. A protion of the flanking DNA is also eliminated during this process. We will isolate the rDNA and the flanking sequences from both the macro-and micronucleus by cloning and determine the nucleotide sequences in these junctions. The alteration process will also be studied during the development of the macronucleus by hybridization. This approach should reveal the nucleotide sequences that are involved in elimination, amplification and breakage, and the molecular mechanisms by which these processes take place. Elimination of DNA and breakage of chromosome also occur in other locations of the genome, and may be associated with a simple repeated hexanucleotide CCCCAA. The C4A2 repeats and the micronuclear specific sequences will be isolated together with their flanking sequences from the 2 nuclei by cloning. The flanking sequences will be used to determine the nature of elimination, and the role of the C4A2 repeats in these processes. This study should help us understand what specific nucleotide sequences are involved in the alteration, and how the entire genome may be reorganized, and perhaps also how these events may be related to the normal developmental process of an eukaryote.