The Systematic Identification and Analysis of Replication Origins in Drosophila

描述：DNA复制是复制每一次细胞分裂的染色体所必需的细胞周期过程。关于复制如何与其他核过程协调，如转录和染色质修饰，人们知之甚少。虽然最近的基因组研究已经证明了DNA复制时间和转录活性之间的相关性，基因组中活跃的转录区域被提前复制，但这种相关性的潜在机制尚不清楚。只有系统地描述后生动物基因组在多种细胞类型中的复制动态，我们才能理解这些过程协调的机制，以维持基因组的稳定性。 我们将使用高密度基因组拼接路径阵列来充分描述果蝇在多个细胞系和组织中的复制程序。具体地说，我们将确定果蝇基因组中所有独特序列的复制时间，识别和定位所有复制的功能起点，并确定复制前复合体(preRC，复制起始所需的一种重要的多蛋白复合体)组装的所有位点。前RC组装位点的高分辨率定位将使我们能够应用计算方法(包括比较基因组学)来识别指导和调控前RC功能的潜在序列基序。最后，我们还将描述多线染色体在完全分化的果蝇组织中的差异复制，以确定扩增或复制不足的基因组区域。多线染色体的差异复制为理解发育线索和染色体结构域如何影响复制程序提供了一个独特的机会。 在增殖的细胞中，基因组的复制是一个关键的细胞周期事件，不仅必须准确地复制基因组，而且还必须复制一次。起始选择和激活的调控是维持基因组稳定性的关键。未能完全复制基因组或不适当地过度复制所选序列可能会导致肿瘤的发生。

DESCRIPTION: DNA replication is an essential cell cycle process required to duplicate the chromosomes each and every cell division. Very little is known about how replication is coordinated with other nuclear processes such as transcription and chromatin modification. Although recent genomic studies have demonstrated a correlation between time of DNA replication and transcriptional activity, with actively transcribed regions of the genome being replicated early, the underlying mechanism driving this correlation remains unclear. Only by systematically characterizing the replication dynamics of a metazoan genome in multiple cell types will we be in a position to understand the mechanisms by which these processes are coordinated to maintain genomic stability. We will use high-density genomic tiling-path arrays to characterize fully the Drosophila replication program in multiple cell lines and tissues. Specifically, we will determine the time of replication for all unique sequences in Drosophila genome, identify and map all functional origins of replication, and identify all sites of prereplicative complex (preRC, an essential multi-protein complex required for replication initiation) assembly. The high-resolution mapping of sites of preRC assembly will enable us to apply computational approaches (including comparative genomics) to identify potential sequence motifs that direct and regulate preRC function. Finally, we will also characterize the differential replication of polytene chromosomes in fully differentiated Drosophila tissues to identify genomic regions that are amplified or underreplicated. The differential replication of polytene chromosomes provides a unique opportunity to understand how developmental cues and chromosomal domains influence the replication program. In proliferating cells, duplication of the genome is a critical cell-cycle event, not only must the genome be copied accurately; it must also be copied exactly once. The regulation of origin selection and activation is essential to maintain genomic stability. The failure to completely replicate the genome or the inappropriate over-replication of select sequences may lead to tumorigenesis.