Significance of metabolic interactions of diatom-diazotrophic associations (DDAs) for ocean ecosystems

硅藻固氮关联（DDA）代谢相互作用对海洋生态系统的意义

• 批准号: 0929015
• 负责人: Rachel Foster
• 金额: $ 30.62万
• 依托单位: University of California-Santa Cruz
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2009
• 资助国家: 美国
• 起止时间: 2009-09-01 至 2014-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0929015&HistoricalAwards=false
• 关键词: Significance; metabolic; interactions; diatom; diazotrophic

Diatoms (i.e., Hemiaulus) with symbiotic heterocystous cyanobacteria (i.e., Richelia) are considered responsible for a significant proportion of di-nitrogen (N2) and carbon (C) fixation in the World's oceans. Although these associations often form large and expansive blooms, measures of their N2 and C fixation are few, and current nitrogen (N) and C budget models do not include their contributions to new and primary production. This is largely due to the difficulty in collection and identification of these unique consortia. The investigators will use newly developed genetic and stable isotope techniques and high resolution nanometer-scale secondary ion mass spectrometry (nanoSIMS) approaches to directly resolve the N2 (and C) fixation contributions of these symbiotic diatoms on a relevant spatial scale.The project will enable investigators to explore the metabolic interactions of diatom-diazatoph symbioses and identify environmental conditions that promote the activity of one symbiosis over the other. The three general questions driving the research are: 1) How do the individual diatom-cyanobacteria symbioses differ with respect to their cell specific N2 and C fixation rates; 2) What is the time scale at which N is transferred from symbiont to host; 3) What are the physical and chemical conditions that promote the activity of the different symbioses. The broader impacts of the research involve advancing our knowledge of metabolic interactions between marine microorganisms, and providing a better understanding of marine planktonic symbioses. In addition, the project will contribute to an on-line web library of photographs for educational outreach. Furthermore, it will support training and education to an undergraduate senior thesis project, and will advance our knowledge of the activity of marine microorganisms.

硅藻（即半藻）与共生的异囊蓝藻（即黎切菌）被认为对世界海洋中相当大比例的二氮（N2）和碳(C)固定负有责任。尽管这些关联常常形成大面积的花华，但它们固定N2和C的措施很少，而且目前的氮(N)和C预算模型没有包括它们对新产量和初级产量的贡献。这主要是由于收集和鉴定这些独特的群体的困难。研究人员将使用新开发的遗传和稳定同位素技术以及高分辨率纳米级二次离子质谱（nanoSIMS）方法直接解析这些共生硅藻在相关空间尺度上的N2（和C）固定贡献。该项目将使研究人员能够探索硅藻-水藻共生的代谢相互作用，并确定促进一种共生活动超过另一种共生活动的环境条件。推动研究的三个一般性问题是：1)单个硅藻-蓝藻共生在细胞特异性N2和C固定率方面有何不同；2) N从共生体向宿主转移的时间尺度是什么？3)促进不同共生活动的物理和化学条件是什么？这项研究更广泛的影响包括提高我们对海洋微生物之间代谢相互作用的认识，并提供对海洋浮游生物共生的更好理解。此外，该项目将有助于建立一个在线网络照片库，用于教育推广。此外，它将支持本科毕业论文项目的培训和教育，并将提高我们对海洋微生物活动的认识。