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; 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.

线粒体对于生物的生存至关重要，因为它们为细胞起作用提供了必要的能量。由于它们的重要性，即使对线粒体的微小变化也会对细胞产生巨大的后果。这包括对线粒体中包含遗传信息的分子（染色体）的变化。线粒体中的遗传信息通常包含在单个圆形染色体上。然而，某些虱子（哺乳动物和鸟类的寄生虫昆虫）的线粒体中的染色体分离到几个较小的圆形碎片上。在虱子的整个进化史中，散布的染色体多次出现，但在大多数其他动物中非常罕见和有害。关于这些碎片染色体如何或为什么在虱子中存在的原因很少。在这个项目中，研究人员将寻求通过比较来自许多不同虱子物种的遗传信息来理解碎片的线粒体染色体。这项研究的结果将提供有关细胞如何工作的洞察力，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活动中创建展示和演示，支持阿肯色州，印第安纳州和伊利诺伊州的多种外展机会。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，研究生和本科生提供培训。该研究将侧重于虱子中与碎片的线粒体基因组（有丝分裂基因组）有关的三个假设：1）非功能，核编码的线粒体基因可以导致有丝分裂基因的分裂，2）损坏有丝分裂的有丝分裂的方法可以从数量上恢复多种多样的孔属性和3），以及3）的肠道脉络性和3），以及3）的脑构态性，以及3）的脑构态性，3）副本可以促进破碎化的增加。为了检验这些假设，研究人员将使用整个基因组序列数据组装有丝分裂基因组和相关的核基因，来自444种虱子，这些虱子代表了四个不同的成枝，它们具有不同水平的有丝分裂组片段化。借助这些数据，研究人员将重建有丝分裂组结构的进化史，并比较四个虱子进化枝中的基因组含量。具体而言，研究人员将1）估计系统基因树以重建线粒体碎片的进化模式，2）检查缺乏核编码的线粒体基因，3）测试放松或阳性选择的签名和4）量化线粒体基因的相对拷贝数。该项目由系统和生物多样性科学和启发竞争性研究的既定计划共同资助（EPSCOR）。该奖项反映了NSF的法定任务，并被认为是值得通过基金会的知识分子和更广泛影响的评估审查标准来通过评估来获得支持的。