The Impact of Retroelement Expression on Centromere Determination in Marsupials

逆转录元件表达对有袋动物着丝粒测定的影响

• 批准号: 0758577
• 负责人: Rachel O'Neill
• 金额: $ 81万
• 依托单位: University of Connecticut
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2008
• 资助国家: 美国
• 起止时间: 2008-07-15 至 2013-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0758577&HistoricalAwards=false
• 关键词: Impact; Retroelement; Expression; Centromere; Determination

The centromere is a cytologically defined entity with a conserved and restricted function in the chromosome: it is the site of kinetochore assembly and spindle attachment during cell division. Proper centromere function is essential to the equal segregation of genetic material at every cell division in all eukaryotes. In addition to its defined cytological role, the centromere is likely to be a key player in karyotypic change coincident with the divergence of species. Its importance in evolution is clearly evidenced by centromeric instability in cases of hybrid dysgenesis and by instances where karyotypic distinctiveness of species is defined exclusively by centromere character and position. Despite its essential function, the centromere is a surprisingly mutable portion of the chromosome, exhibiting little sequence conservation in the few organisms in which it has been studied. This region of the genome remains largely uncharted in most model organisms. Centromeres have long been thought to comprise non-coding and transcriptionally inactive DNA. Surprising new evidence suggests that active retroelements residing in centromeres and the transcripts they produce may play a critical role in centromere structure, function and evolution. This project will investigate the genomic features associated with centromere competence. Preliminary studies indicate that the centromeres of the wallaby Macropus eugenii are small and tractable with respect to BAC mapping and contiguous sequence development. The centromeres of this species carry actively transcribed retroelements and repeated sequences that may facilitate centromere function. This research will focus specifically on the centromere of chromosome 7 of the tammar wallaby, Macropus eugenii and will directly test hypotheses addressing the involvement of retroelements in centromere determination and maintenance, and ultimately chromosome evolution.As the field of genomics has shifted from a focus on the small percentage of DNA that codes for proteins to the large percentage of DNA that does not, there has been a corresponding shift from traditional genetic studies to a completely different paradigm: comparative genomics. The application of comparative studies involving genomic sequences of evolutionarily distinct and informative taxa has led to remarkable advances in identification of regulatory domains within conserved sequences. For the first time, the opportunity exists to examine a conserved, centromere-specific retroelement in the context of its domestication for use in centromere function in mammals. The power of this approach is underscored by the fact that comparative methods are now targeting analyses of functionally important genomic elements in non-coding regions across several vertebrate genome projects. Evolutionary comparisons are equally critical in advancing an understanding of regions of the genome, like the centromere, that are conserved in function but are comprised of widely divergent non-coding DNA. In addition, this proposal includes integration of a significant education component in its research endeavor that targets students at various education levels. Graduate and undergraduate students will directly participate in this research, including contributions to scientific workshops and conferences and involvement in the Research Experience for Undergraduates program. Novel curriculum development will be supported by this proposed work. Several technical approaches in the research design will be incorporated into modular laboratory courses, developed in the previous award period, for students enrolled in the Professional Sloan Masters program in Applied Genomics. The research outlined in this proposal supports outreach activities through the participation of two to four high school students each summer. This will be implemented in collaboration with the UCONN Mentor Connection program, which allows participants to join this laboratory and conduct research under the mentoring of the principal investigator.

着丝粒是细胞学定义的实体，在染色体中具有保守和限制的功能：它是细胞分裂期间动粒组装和纺锤体附着的位点。在所有真核生物中，正确的着丝粒功能对于在每次细胞分裂中遗传物质的平等分离是必不可少的。除了其明确的细胞学作用外，着丝粒可能是与物种分化一致的核型变化的关键参与者。它在进化中的重要性是清楚地证明了着丝粒的不稳定性的情况下，杂种发育不良和物种的核型独特性是完全由着丝粒的特点和位置。尽管它的基本功能，着丝粒是一个令人惊讶的可变部分的染色体，表现出很少的序列保守性在少数生物体中，它已被研究。基因组的这一区域在大多数模式生物中仍然是未知的。长期以来，着丝粒一直被认为由非编码和转录失活的DNA组成。令人惊讶的新证据表明，活跃的逆转录分子驻留在着丝粒和他们产生的转录本可能在着丝粒的结构，功能和进化中发挥关键作用。本计画将探讨与着丝粒能力相关的基因组特徴。初步研究表明，小袋鼠Macropus eugenii的着丝粒很小，对于BAC作图和连续序列开发来说很容易处理。该物种的着丝粒携带活跃转录的逆转录元件和重复序列，可能有助于着丝粒功能。这项研究将特别关注tammar wallaby，Macropus eugenii的7号染色体的着丝粒，并将直接测试解决着丝粒确定和维持中的逆转录因子参与的假设，并最终染色体进化。随着基因组学领域从关注编码蛋白质的小百分比DNA转移到不编码蛋白质的大百分比DNA，从传统的遗传学研究到完全不同的范式：比较基因组学也发生了相应的转变。涉及进化上不同的和信息类群的基因组序列的比较研究的应用，导致了显着的进展，在保守序列内的调节结构域的识别。这是第一次，有机会在哺乳动物的着丝粒功能中使用其驯化的背景下，检查一个保守的，着丝粒特异性的retroelement。这种方法的力量是强调的事实，比较的方法，现在有针对性的分析功能重要的基因组元件在非编码区在几个脊椎动物基因组计划。进化比较在推进对基因组区域的理解方面同样至关重要，如着丝粒，这些区域在功能上是保守的，但由差异很大的非编码DNA组成。此外，该提案还包括将一个重要的教育组成部分纳入其针对不同教育水平学生的研究奋进。研究生和本科生将直接参与这项研究，包括对科学研讨会和会议的贡献，以及参与本科生项目的研究经验。新的课程开发将支持这项拟议的工作。研究设计中的几种技术方法将被纳入模块化实验室课程中，这些课程是在上一个奖项期间为参加应用基因组学专业斯隆硕士课程的学生开发的。本提案中概述的研究通过每年夏季两至四名高中生的参与支持外联活动。这将与UCONN Mentor Connection计划合作实施，该计划允许参与者加入该实验室并在主要研究者的指导下进行研究。