Dimensions: Collaborative Research: Functional Diversity of Marine Eukaryotic Phytoplankton and Their Contributions to the C and N Cycling

维度：合作研究：海洋真核浮游植物的功能多样性及其对碳氮循环的贡献

• 批准号: 1136477
• 负责人: Andrew Allen
• 金额: $ 60万
• 依托单位: J. Craig Venter Institute, Inc.
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2012
• 资助国家: 美国
• 起止时间: 2012-01-01 至 2014-12-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1136477&HistoricalAwards=false
• 关键词: Dimensions; Collaborative; Research; Functional; Diversity

Intellectual Merit: Phytoplankton form the basis of the marine food web and thus are a crucial element in the biological pump whereby CO2 from the atmosphere is sequestered in the deep ocean. For decades, biological oceanography focused on the eukaryotic phytoplankton. In the 1970-80s, it was discovered that the single celled picocyanobacteria are numerically dominant in the oceans and are responsible for a large fraction of ocean photosynthesis. What ensued was the growth of a new paradigm in which the picocyanobacteria dominate upper ocean biology and biogeochemistry. In fact, new data support the classic view that the eukaryotic phytoplankton are disproportionately important in both N and C cycling, even in regions where very small cells dominate the biomass and where the eukaryotes themselves are in the "pico" size fraction. In oligotrophic environments, where very small cells dominate, in situ recycling appears to supply most of the nitrogen (i.e., ammonium) required for primary production. New nitrate supply must balance N loss from the system, however, and new data suggest that this nitrate is an important contribution to phytoplankton N, even in the oceanic deserts. It is not known whether the nitrate supply in these systems is used by the entire assemblage or predominantly by larger phytoplankton (essentially entirely eukaryotic). On the basis of still quite limited molecular surveys, we now recognize that the diversity of both large and small eukaryotic phytoplankton is greater than previously thought and that the most abundant and widespread eukaryotes are probably not in culture and may not be closely related to known cultivated organisms. This project will investigate the taxonomic, genetic and functional diversity of eukaryotic phytoplankton at two North Atlantic sites (subarctic and subtropical) in two seasons.The PIs will use diagnostic microarrays for community analysis based on functional genes (both DNA and RNA) and next generation sequencing (i.e., transcriptomics using 454 technology) to identify the players, both in terms of community composition and activity, and to explore the functional diversity of the natural assemblage. In order to identify which groups are active in C and N assimilation and which N source is being utilized by the different size and functional groups, both filter-separated and flow cytometry-sorted samples will be used to 1) measure 13C primary production and 15N assimilation by incubations with isotope tracers, 2) measure the natural stable N isotope signatures of different taxonomic groups and 3) link the molecular diversity to the functional diversity in C and N transformations. Using flow cytometry linked to mass spectrometry, these investigators have found an unexpectedly strong differentiation in the form of N assimilated by prokaryotes and eukaryotes, with eukaryotes being more dynamic.Integration: This project will investigate the taxonomic, genetic and functional diversity of eukaryotic phytoplankton and to link this diversity and assemblage composition to the carbon and nitrogen biogeochemistry of the surface ocean. Taxonomic diversity will be investigated by identifying the components of the phytoplankton assemblages using molecular, chemical and microscope methods. Genetic diversity will be explored at several levels, including direct sequencing of clone libraries of key functional genes and metatranscriptomic sequencing and microarray analysis of size fractionated/sorted phytoplankton assemblages. Using natural abundance and tracer stable isotope methods, genetic and taxonomic diversity will be linked to functional diversity in C and N assimilation in size- fractionated and taxon-sorted populations.Broader Impacts: The broader impacts of this project include contributions to fundamental research and education: 1) continued development of new advanced methods of isotope analysis in environmental samples, with increasing breadth of applications in biogeochemistry and biodiversity; 2) undergraduate teaching in foundation courses on climate and environmental science to recruit freshmen and sophomore students into the science majors; 3) undergraduate research experience through internships and senior thesis research (a requirement at Princeton) for upper level undergraduates; 4) training the next generation of microbial ecology/ biogeochemistry researchers through classroom and research experience at the graduate level. In addition, a new module will be created (The Forests and Deserts of the Ocean) for the Princeton outreach program for middle school teachers (QUEST, Questioning Underlies Effective Science Teaching).

智力优势：浮游植物构成了海洋食物网的基础，因此是生物泵的关键元素，大气中的二氧化碳被隔离在深海中。几十年来，生物海洋学一直关注真核浮游植物。在20世纪70-80年代，人们发现单细胞的picocyanobacteria在海洋中数量上占主导地位，并负责海洋光合作用的很大一部分。随之而来的是一种新的范式的发展，在这种范式中，碧青杆菌主导着上层海洋生物学和生物地球化学。事实上，新的数据支持了经典观点，即真核浮游植物在N和C循环中都是不成比例的重要，即使在非常小的细胞占主导地位的生物量和真核生物本身处于“微”大小部分的区域也是如此。在贫营养环境中，非常小的细胞占主导地位，就地再循环似乎提供了初级生产所需的大部分氮（即铵）。然而，新的硝酸盐供应必须平衡系统中的氮损失，新的数据表明，即使在海洋沙漠中，这种硝酸盐也是浮游植物氮的重要贡献。目前尚不清楚这些系统中的硝酸盐供应是被整个组合使用，还是主要由较大的浮游植物（基本上全部是真核植物）使用。在仍然相当有限的分子调查的基础上，我们现在认识到，大大小小的真核浮游植物的多样性比以前认为的要大，最丰富和最广泛的真核生物可能不在培养中，也可能与已知的培养生物没有密切的关系。本项目将分两个季节在北大西洋两个地点（亚北极和亚热带）调查真核浮游植物的分类、遗传和功能多样性。pi将使用诊断微阵列进行基于功能基因（DNA和RNA）和下一代测序（即使用454技术的转录组学）的群落分析，以确定群落组成和活性方面的参与者，并探索自然组合的功能多样性。为了确定哪些群体活跃在C和N同化和N源是利用不同的大小和官能团,filter-separated和流cytometry-sorted样本将用于1)测量13 C初级生产和15 N同化通过与同位素示踪剂孵化项目,2)测量不同分类的自然稳定N同位素签名组和3)链接功能多样性的分子多样性在C和N转换。利用流式细胞术与质谱相结合，这些研究人员发现，原核生物和真核生物吸收N的形式出乎意料地强烈分化，真核生物更具活力。整合：本项目将研究真核浮游植物的分类、遗传和功能多样性，并将这种多样性和组合组成与海洋表面的碳氮生物地球化学联系起来。利用分子、化学和显微镜方法鉴定浮游植物组合的组成部分，研究其分类多样性。遗传多样性将在多个层面进行探索，包括关键功能基因克隆文库的直接测序，以及大小分拣/分拣浮游植物组合的亚转录组测序和微阵列分析。利用自然丰度和示踪稳定同位素方法，遗传和分类多样性将与大小分级和分类群中C和N同化的功能多样性联系起来。更广泛的影响：本项目的更广泛影响包括对基础研究和教育的贡献：1)继续发展新的先进的环境样品同位素分析方法，在生物地球化学和生物多样性方面的应用越来越广泛；2)气候与环境科学基础课程本科教学，招收理科专业大一、大二学生；3)通过实习和高级论文研究（普林斯顿大学的要求）获得本科研究经验；4)通过研究生阶段的课堂和研究经验培养下一代微生物生态学/生物地球化学研究人员。此外，将为普林斯顿中学教师拓展计划（QUEST，有效科学教学的基础）创建一个新的模块（海洋的森林和沙漠）。