Impact of secondary endosymbiosis on eukaryotic genome evolution

次级内共生对真核基因组进化的影响

• 批准号: 356738-2007
• 负责人: Archibald, John
• 金额: $ 3.86万
• 依托单位: Dalhousie University
• 依托单位国家: 加拿大
• 项目类别: Special Research Opportunity Program - Project
• 财政年份: 2009
• 资助国家: 加拿大
• 起止时间: 2009-01-01 至 2010-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=432089
• 关键词: Impact; secondary; endosymbiosis; eukaryotic; genome

The process of endosymbiosis has been a monumental force in the origin and diversification of eukaryotic (nucleus-containing) organisms. The primary endosymbiotic origin of plastids (chloroplasts) occurred more than a billion years ago and spawned three lineages-the green algae (and their land plant relatives), red algae and glaucophytes-whose energy-generating capabilities paved the way for a transformation of the biosphere. The photosynthetic organelles of red and green algae have spread to unrelated eukaryotes by 'secondary endosymbiosis'-the engulfment and retention of an algal cell inside a non-photosynthetic host. Secondary endosymbiosis has given rise to some of the most abundant and ecologically significant aquatic photosynthesizers on the planet, including heterokonts (e.g., diatoms and giant kelp) and the 'red tide'-causing dinoflagellates. We are leading a DOE Joint Genome Institute (JGI)-funded effort to sequence the nuclear genomes of two secondary plastid-containing algae of pivotal evolutionary and cell biological significance, the cryptomonad Guillardia theta and the chlorarachniophyte Bigelowiella natans. Together, these organisms are unique in that they still possess the nucleus (nucleomorph) and cytoplasm of their algal endosymbionts in a highly reduced and simplified form. The limited coding capacity of the cryptomonad and chlorarachniophyte nucleomorphs indicates that the nuclear genomes of these organisms have been repositories for thousands of endosymbiont-derived genes throughout their evolutionary history. The goal of this project is to (i) spearhead community efforts to 'annotate' the Guillardia and Bigelowiella genome sequences (ii) establish the bioinformatic resources with which to store, manage and analyze our whole genome datasets, and (iii) perform a variety of genomic analyses related to the DOE-JGI project's main goals. Comparing and contrasting the Guillardia and Bigelowiella genome sequences will provide an unprecedented window into the process of secondary endosymbiosis and the integration of their respective hosts and endosymbionts at the genetic, biochemical and cellular level.

在真核(含核)生物的起源和多样化中，内共生过程一直是一股巨大的力量。质体(叶绿体)的主要内生共生起源于10亿多年前，并产生了三个谱系--绿藻(及其陆地植物近亲)、红藻和蓝藻--它们的能量产生能力为生物圈的转变铺平了道路。红藻和绿藻的光合细胞器通过“二次内共生”扩散到不相关的真核生物体内--即吞噬和滞留在非光合作用宿主内的藻细胞。次生内生共生产生了地球上一些最丰富和最具生态意义的水生光合作用生物，包括异形藻(如硅藻和巨藻)和引起红潮的甲藻。我们正在领导一项由美国能源部联合基因组研究所(JGI)资助的工作，对两种具有关键进化和细胞生物学意义的次生体藻类--隐单胞藻Guillardia theta和绿藻Bigelowiella Natans--的核基因组进行测序。总而言之，这些生物是独一无二的，因为它们仍然以高度简化和简化的形式拥有其藻类内共生体的核(核形态)和细胞质。隐单胞菌和绿藻核型的有限编码能力表明，在它们的进化历史中，这些生物的核基因组一直是数以千计的内共生体衍生基因的储存库。该项目的目标是(I)带头开展社区工作，对Guillardia和Bigelowiella基因组序列进行“注释”；(Ii)建立生物信息学资源，用于存储、管理和分析我们的整个基因组数据集；以及(Iii)执行与DOE-JGI项目主要目标相关的各种基因组分析。比较和对比Guillardia和Bigelowiella的基因组序列将为了解二次内共生过程以及它们各自的宿主和内共生菌在遗传、生化和细胞水平上的整合提供一个前所未有的窗口。