Collaborative Research: Unraveling the phylogenetic and evolutionary patterns of fragmented mitochondrial genomes in parasitic lice

合作研究：揭示寄生虱线粒体基因组片段的系统发育和进化模式

• 批准号: 2328119
• 负责人: Stephen Cameron
• 金额: $ 25.15万
• 依托单位: Purdue University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2024
• 资助国家: 美国
• 起止时间: 2024-02-01 至 2027-01-31
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2328119&HistoricalAwards=false
• 关键词: Collaborative; Research; Unraveling; phylogenetic; evolutionary

Mitochondria are critical for the survival of organisms because they provide the energy necessary for cells to function. Because of their importance, even small changes to the mitochondria can have drastic consequences for the cell. This includes changes to the molecules (chromosomes) that contain genetic information in the mitochondria. Genetic information in the mitochondria is usually contained on a single, circular chromosome. However, chromosomes in the mitochondria of some species of lice (small, parasitic insects of mammals and birds) are separated onto several smaller, circular fragments. Fragmented chromosomes arose multiple times throughout the evolutionary history of lice, but are very rare and harmful in most other animals. Very little is known about how or why these fragmented chromosomes exist in lice. In this project, the researchers will seek to understand fragmented mitochondrial chromosomes by comparing genetic information from many different species of lice. The results from this research will provide insight into how cells work and could help scientists to better understand human mitochondrial diseases. The project will support multiple outreach opportunities in Arkansas, Indiana, and Illinois through the creation of displays and presentations at community STEM events. The project will also provide training for a postdoctoral researcher, graduate students, and undergraduate students working on the project, and for the broader research community through two workshops on analyzing mitochondrial genome data. The research will focus on three hypotheses related to fragmented mitochondrial genomes (mitogenomes) in lice: 1) non-functional, nuclear-encoded mitochondrial genes can result in fragmentation of the mitogenome, 2) fragmented mitogenomes allow for a reduction in purifying selection from mito-nuclear incompatibility, and 3) selection for a balanced number of mitochondrial gene copies can promote an increase in fragmentation. To test these hypotheses, the researchers will use whole genome sequence data to assemble mitogenomes and relevant nuclear genes from 444 species of lice that represent four distinct clades that have varying levels of mitogenome fragmentation. With these data, the researchers will then reconstruct the evolutionary history of mitogenome structure and compare genomic content in the four clades of lice. Specifically, the researchers will 1) estimate a phylogenomic trees to reconstruct the evolutionary patterns of mitochondrial fragmentation, 2) examine the absence of nuclear-encoded mitochondrial genes, 3) test for signatures of relaxed or positive selection, and 4) quantify the relative copy number of mitochondrial genes. This project is jointly funded by Systematics and Biodiversity Science and the Established Program to Stimulate Competitive Research (EPSCoR).This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

线粒体对于生物体的生存至关重要，因为它们提供细胞发挥功能所需的能量。由于线粒体的重要性，即使线粒体发生微小变化也会对细胞产生严重后果。这包括线粒体中含有遗传信息的分子（染色体）的变化。线粒体中的遗传信息通常包含在单个环形染色体上。然而，某些虱子物种（哺乳动物和鸟类的小型寄生昆虫）的线粒体中的染色体被分成几个较小的圆形片段。在虱子的进化史上，断裂的染色体多次出现，但在大多数其他动物中非常罕见且有害。关于这些碎片染色体如何或为何存在于虱子中，人们知之甚少。在这个项目中，研究人员将通过比较许多不同种类虱子的遗传信息来寻求了解线粒体染色体碎片。这项研究的结果将深入了解细胞如何工作，并可以帮助科学家更好地了解人类线粒体疾病。该项目将通过在社区 STEM 活动中进行展示和演示，为阿肯色州、印第安纳州和伊利诺伊州的多个外展机会提供支持。该项目还将通过两个分析线粒体基因组数据的研讨会，为从事该项目的博士后研究员、研究生和本科生以及更广泛的研究界提供培训。该研究将重点关注与虱子中片段化线粒体基因组（线粒体基因组）相关的三个假设：1）非功能性核编码线粒体基因可能导致线粒体基因组片段化，2）片段化线粒体基因组可以减少线粒体的纯化选择-核不相容性，以及3)选择平衡数量的线粒体基因拷贝可以促进碎片的增加。为了检验这些假设，研究人员将使用全基因组序列数据来组装来自 444 个虱子物种的线粒体基因组和相关核基因，这些虱子代表了具有不同水平线粒体基因组碎片的四个不同分支。利用这些数据，研究人员将重建线粒体基因组结构的进化历史，并比较虱子四个分支的基因组内容。具体来说，研究人员将1）估计系统发育树以重建线粒体碎片的进化模式，2）检查核编码线粒体基因的缺失，3）测试宽松或正选择的特征，4）量化相对拷贝线粒体基因的数量。该项目由系统学和生物多样性科学以及刺激竞争性研究既定计划 (EPSCoR) 联合资助。该奖项反映了 NSF 的法定使命，并通过使用基金会的智力价值和更广泛的影响审查标准进行评估，被认为值得支持。