COLLABORATIVE RESEARCH: Environmental and internal influences on the activities of the Calvin- and reductive citric acid cycles in hydrothermal vent symbiosis Riftia pachyptila

合作研究：热液喷口共生 Riftia pachyptila 中卡尔文循环和还原柠檬酸循环活动的环境和内部影响

• 批准号: 1257755
• 负责人: Peter Girguis
• 金额: $ 30.5万
• 依托单位: Harvard University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2013
• 资助国家: 美国
• 起止时间: 2013-06-01 至 2017-05-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1257755&HistoricalAwards=false
• 关键词: COLLABORATIVE; RESEARCH; Environmental; internal; influences

All life on Earth depends upon the fixation of carbon dioxide to organic carbon by organisms that power this process with light energy or high-energy chemicals. There are four known pathways that catalyze carbon fixation. Based on phylogenetic distributions and functional attributes, it has been posited that the Calvin Benson Bassham cycle, found in plants, algae, and some bacteria, dominates in aerobic terrestrial and marine aerobic habitats due to its resilience to oxygen, while other 'oxygen sensitive' carbon fixation pathways are relegated to hypoxic or anoxic environs like vents and hot springs. Contrary to this supposition, there are symbioses found in hypoxic diffuse flows around hydrothermal vents in which the bacterial partner uses the Calvin Benson Bassham cycle. Tubeworm-bacterial symbioses, in particular Riftia pachyptila ("Riftia"), are the dominant keystone species at hydrothermal vents in the Pacific Ocean. These symbiotic systems fix carbon at mass specific rates comparable to the fastest growing plants. Surprisingly, recent studies suggest that the bacterial symbionts use two carbon fixation pathways, the Calvin Benson Bassham cycle and the reductive tricarboxylic acid cycle. The use of these two pathways by a single organism (the bacterium) to fix carbon is unprecedented, and may be a strategy to cope with the high variability in environmental conditions encountered by hydrothermal vent organisms. For the work proposed here, Riftia will be incubated in high-pressure aquaria under conditions that mimic the environmental variations found in situ. Biochemical assays on the bacteria and tubeworm host will be used to ascertain the relationship between environmental conditions, metabolic activity and differential use of the two pathways, to understand how they act in concert to sustain carbon fixation in a dynamic environment. These data will considerably further the understanding of the influence of environment on carbon fixation by bacteria as well as plants, and will also be helpful for determining why different organisms have the different carbon fixing pathways.We are equally committed to the proposed scientific research and our proposed education and outreach. We plan to support three major programs: (1) graduate student development (2) undergraduate mentoring, and (3) the design of high-impact educational curricula using real research data and experiences. This study will enable the support and training of undergraduate and graduate students who will be intimately involved in designing and engineering the experiments, analyzing the data, and formally presenting and documenting the work. The proposed research contains significant field and laboratory components, which affords students and teachers the opportunities to participate in this project at a variety of levels.

地球上的所有生命都取决于二氧化碳通过用轻能或高能化学物质供电的生物固定在有机碳上。有四种已知的途径可以催化碳固定。 Based on phylogenetic distributions and functional attributes, it has been posited that the Calvin Benson Bassham cycle, found in plants, algae, and some bacteria, dominates in aerobic terrestrial and marine aerobic habitats due to its resilience to oxygen, while other 'oxygen sensitive' carbon fixation pathways are relegated to hypoxic or anoxic environs like vents and hot springs.与这种假设相反，在缺氧弥漫性流动中发现了共生，细菌伴侣使用Calvin Benson Bassham循环。 小管 - 细菌 - 细菌共生菌，尤其是Riftia Pachyptila（“ Riftia”），是太平洋中水热通风孔的主要基石物种。 这些共生系统以与生长最快的植物相当的质量比率修复碳。 令人惊讶的是，最近的研究表明，细菌共生体使用两种碳固定途径，Calvin Benson Bassham循环和还原性三羧酸周期。 单个生物体（细菌）固定这两种途径是前所未有的，并且可能是应对水热孔生物体遇到的环境条件的较高变化的策略。 对于此处提出的工作，在模仿原位环境变化的条件下，Riftia将在高压水族箱中孵育。 对细菌和小管宿主的生化测定将用于确定环境条件，代谢活性和两种途径的差异使用之间的关系，以了解它们在动态环境中如何共同行动以维持碳固定。 这些数据将大大理解环境对细菌和植物固定碳固定的影响，也将有助于确定为什么不同的生物具有不同的碳固定途径。我们同样致力于拟议的科学研究以及拟议的教育和外展。 我们计划支持三个主要计划：（1）研究生发展（2）本科指导，以及（3）使用实际的研究数据和经验设计高影响力教育课程的设计。这项研究将使本科生和研究生的支持和培训能够亲密地参与设计和工程实验，分析数据，并正式介绍和记录工作。 拟议的研究包含重要的领域和实验室组件，这为学生和老师提供了各种层次参与该项目的机会。