Comparative Genomics of A Rice Centromere

着丝粒是细胞学(视觉上)定义的实体，具有高度保守的功能。它负责染色体姐妹染色单体的聚集，也是动粒的组装部位，动粒是一种蛋白质结构，在细胞分裂过程中将染色体与纺锤体纤维联系在一起。在大多数多细胞真核生物中，着丝粒嵌入到异染色质中，异染色质是DNA的一种紧密包装形式，并与长长的卫星重复序列有关，在这些重复序列中，基因基本上缺失。因此，着丝粒传统上被认为是一个高度异色和遗传沉默的染色体区域。最近对水稻8号染色体着丝粒(Cen8)和人类新着丝粒(新形成的着丝粒区域)的研究表明，着丝粒起源于基因区域。该项目将以水稻Cen8为模型，重点研究着丝粒进化。具体地说，该项目将开发基于细菌人工染色体(BAC)的物理图谱，该图谱跨越六个二倍体野生稻物种的Cen8，并从六个着丝粒中的每一个产生大约一兆碱基的DNA序列。6个着丝粒的功能边界将用细胞遗传学和分子方法确定。通过比较序列分析将揭示与这六个着丝粒相关的结构重排和序列分歧。将探索Cen8相关基因的表达和进化，以了解这些基因如何适应独特的染色体结构域。该项目的结果将揭示着丝粒的进化，并将为研究位于异染色质和重组抑制的染色体区域的基因的进化奠定基础。获取项目成果序列数据和基因注释结果将通过基因库、项目网站(可通过http://www.omap.org/)和Gramene(http://www.gramene.org).)等社区数据库访问)向公众提供

The centromere is a cytologically (visually) defined entity with highly conserved functions. It is responsible for chromosomal sister chromatid cohesion and is the site for the assembly of kinetochore, a protein structure which links chromosomes to spindle fibers during cell division. In most multicellular eukaryotes, the centromeres are embedded within heterochromatin, a tightly packed form of DNA, and are associated with long tracts of satellite repeats in which genes are largely absent. Thus, the centromere is traditionally viewed as a highly heterochromatic and genetically silent chromosomal domain. Recent research work from the centromere of rice chromosome 8 (Cen8) as well as the neocentromeres (newly forming centromeric regions) from humans suggest that centromeres originated from genic regions. This project will focus on centromere evolution using rice Cen8 as a model. Specifically, this project will develop bacterial artificial chromosome (BAC)-based physical maps that span Cen8 in six diploid wild rice species and produce approximately one megabase of DNA sequence from each of the six centromeres. The functional boundary of the six centromeres will be determined using cytogenetic and molecular methods. The structural rearrangements and sequence divergence associated with the six centromeres will be revealed by comparative sequence analysis. Expression and evolution of Cen8-associated genes will be explored to understand how such genes adapt to a unique chromosomal domain. The results from this project will shed light on centromere evolution and will also build a foundation to study the evolution of genes located in heterochromatic and recombinationally-suppressed chromosomal domains. Access to Project OutcomesSequence data and gene annotation results will be made available to the public through GenBank, the project website (accessible through http://www.omap.org/) and community databases such as Gramene (http://www.gramene.org).