GENE AMPLIFICATION AND ELIMINATION IN TETRAHYMENA

我建议研究各种不同的发展过程， 在模型系统四膜虫中的真核基因组的组织。 DNA 消除，rDNA扩增和染色体断裂都已显示 发生在这种生物体中，并将进行详细研究。 rDNA存在 在这个生物体的染色体上是一个单拷贝序列。 期间 在发育过程中，染色体断裂发生在该基因附近，rDNA被 从染色体中释放出来进行扩增。 侧翼的一部分 DNA也在这个过程中被清除。 我们将分离rDNA， 通过克隆从大核和微核中获得侧翼序列， 确定这些连接处的核苷酸序列。 变更 在大核的发育过程中，也将研究这一过程， 杂交方法 这种方法应该可以揭示 参与消除、扩增和断裂， 这些过程发生的机制。 去除DNA和 染色体断裂也发生在基因组的其他位置， 与简单重复的六核苷酸CCCCAA相关。 C4A2 重复序列和微核特异性序列将被一起分离 通过克隆从2个细胞核中获得它们的侧翼序列。 侧翼 序列将用于确定消除的性质和作用 C4A2在这些过程中重复。 这项研究应该可以帮助我们 了解哪些特定的核苷酸序列参与了 改变，以及整个基因组如何重组，也许还有 这些事件如何可能与正常的发展过程中， 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.