Microbial Genome Sequencing: Genome Sequence of Prochloron didemni: An Obligate Cyanobacterial Symbiont

在这个项目中，白鲜菌的基因组将被测序、注释并用于比较基因组研究。白鲜菌是一种光合作用细菌，与在珊瑚礁中发现的原始动物共生。这种共生很重要，原因有很多，包括(1)宿主(珊瑚礁海鞘)是脊索动物的原始代表--因此这项研究可能有助于理解细菌与其他脊索动物(如人类)之间的共生；(2)共生体是蓝藻的原叶绿藻，因此是植物(叶绿体)光合器官的近亲；(3)目前还没有蓝藻共生体的基因组可用。对基因组的分析将用于阐明脊索动物和细菌之间共生的基因，进一步确定原绿藻独特的光合作用特性，并确定哪些因素在将自由生活的蓝藻转化为专性共生体的过程中起重要作用。此外，该项目应有助于理解共生的更广泛背景，例如互惠和致病联系之间的区别，微生物共生体在海洋无脊椎动物生态中的深刻作用，以及通过共生创新的机制，这是生命史上的一个主要过程。该项目将是基因组研究所(TIGR)、犹他大学和加州大学圣地亚哥分校之间的合作努力，将有来自这些研究所和来自共生发生的帕劳共和国的研究生和本科生参与。也许最重要的是，光合作用是固定大气中碳的主要途径。因此，更好地了解碳固定途径的多样性，特别是在与植物和藻类叶绿体相关的生物体中，可能有助于努力了解全球碳循环，并最终减轻人类活动向大气释放碳的影响。

In this project, the genome of Prochloron didemni, a photosynthetic bacteria that lives in a symbiosis with a primitive animal found in coral reefs, will be sequenced, annotated and used for comparative genomic studies. This symbiosis is important for many reasons including (1) that the host (the coral reef ascidian Lissoclinum patella) is a primitive representative of the chordate animals - thus this study may help understand symbioses between bacteria and other chordates such as humans; (2) that the symbiont is a cyanobacterial prochlorophyte and thus is a close relative of the photosynthetic organelles of plants (chloroplasts); and (3) there are no genomes currently available from cyanobacteria symbionts. Analysis of the genome will be used to elucidate genes responsible for symbioses between chordates and bacteria, to further define the unique photosynthetic characteristics of prochlorophytes and to determine which factors are important in the conversion of free-living cyanobacteria into obligate symbionts. In addition, this project should help in understanding the broader context of symbiosis such as the distinction between mutualistic and pathogenic associations, the profound role of microbial symbionts in marine invertebrate ecology, and the mechanisms of innovation through symbiosis, a major process in the history of life. This project will be a collaborative effort between The Institute for Genomic Research (TIGR), the University of Utah and the University of California San Diego and will involve graduate and undergraduate students from these institutes and from the Republic of Palau where the symbiosis occurs. Perhaps most importantly, photosynthesis represents the primary pathway for fixation of carbon from the atmosphere. Thus a better understanding of the diversity of carbon fixation pathways, especially in the organisms related to plant and algal chloroplasts, will potentially help in efforts to understand global carbon cycles and eventually to mitigate the effects of carbon being released into the atmosphere by human activity.