Dimensions:Collaborative Research: Oligotrophic phytoplankton community response to changes in N substrates and the resulting impact on genetic, taxonomic and functional diversity

智力上的优点。海洋浮游植物是原核和真核单细胞生物的多样化群体，约占全球碳固定量的50%。氮（N）是微生物生长的必需元素，但在亚热带海洋环流的广大地区，生物可利用氮的浓度极低（亚微摩尔至纳摩尔浓度），通常会限制浮游植物的生长。浮游植物类群不同的遗传能力，采取和同化营养物质，因此竞争不同的化学形式的N（NH 4+，NO3-和尿素）和供应这些含N化合物是重要的控制浮游植物的生长，生产力，并最终生态系统功能。人类活动已经改变了浮游植物氮的形式和供应，随着环境扰动的增加，这种影响将加速。然而，到目前为止，有有限的信息如何N的形式和通量影响海洋浮游植物群落组成和初级生产力。同样，确定应对机制对于评估海洋生态系统功能如何应对全球气候变化至关重要。该项目旨在确定浮游植物多样性的分类、遗传和功能维度如何与地球上最大的水生生境之一北太平洋亚热带环流中不同N基质（NH 4+、NO3-和尿素）的可用性的社区级响应相关联。该项目将描述浮游植物群落组成变化和基因表达、光合作用性能、碳固定以及浮游植物组合中不同类群对不同氮化合物的单细胞水平氮和碳吸收。该研究项目在使用最先进的方法，包括快速重复率荧光测定法，纳米级二次离子质谱法和全面的海洋微生物群落微阵列，调查社区到单细胞水平的功能和物种（菌株）特异性基因表达模式方面是独一无二的。研究结果将提供预测性的理解，了解关键氮库（N）的可用性变化如何影响海洋中浮游植物的动态和功能。该项目旨在了解连接氮的代谢到开放海洋中浮游植物生物多样性的生态基础。将营养物（在这种情况下为N）的生态竞争与浮游植物多样性联系起来的基本概念将为理解生态系统功能如何与生物多样性联系起来提供一个通用框架。通过应用最先进的分子和遗传方法来解决生态问题，该项目旨在开发一种创新的工作流程来评估环境中的真核和原核基因功能，并为研究生和博士后研究人员提供现代分析和生物信息学培训。微阵列工具的设计涉及到更大的海洋微生物学社区，并可用于更大的科学界，该项目是第一个实施。微生物生态学和基因组学的基本概念将用于本科生和研究生课程的教育活动以及本科生和研究生的研究培训。该项目支持的学生和博士后研究人员将在加州州弗朗西斯科的科学博物馆Exploratorium从事微生物和分子生物学展示和演示的开发。项目人员将合作开发探索资料馆的模块。探索馆伙伴关系将为学生和博士后提供一个教育推广机制，以及向公众宣传海洋微生物和基因组学的重要性的有效手段（每年超过60万人次）。PI将与夏威夷大学微生物海洋学中心的教育团队合作：研究和教育（C-MORE）学者计划，招募一名本科生参与该项目。C-MORE学者计划旨在通过确定教师导师与STEM学科传统上代表性不足的学生合作来促进劳动力多样性。该项目整合了微生物生物多样性的多个视角。该项目旨在了解含氮营养物质如何通过浮游植物分类群的差异基因表达和功能特性来调节浮游植物群落的分类，遗传和功能多样性。

Intellectual merit. Marine phytoplankton are a diverse group of Prokaryotic and Eukaryotic unicellular organisms that account for approximately 50% of global carbon fixation. Nitrogen (N) is an essential element for microbial growth, but concentrations of bioavailable nitrogen in vast regions of subtropical ocean gyres are extremely low (submicromolar to nanomolar concentrations), and generally limit phytoplankton growth. Phytoplankton taxa differ in their genetic capabilities to take up and assimilate nutrients, and thus competition for different chemical forms of N (NH4+, NO3- and urea) and supply of these N-containing compounds are important controls on phytoplankton growth, productivity, and ultimately ecosystem function. The form and supply of N to phytoplankton have already been altered by anthropogenic activities, and with increasing environmental perturbations the effects will accelerate. To date however, there is limited information on how the N forms and fluxes impact the marine phytoplankton community composition and primary production. Similarly, determining the mechanisms of the response are crucial to assessing how ocean ecosystem function will respond to global climate change. This project seeks to determine how taxonomic, genetic and functional dimensions of phytoplankton diversity are linked with community-level responses to the availability of different N substrates (NH4+, NO3-, and urea) in one of Earth's largest aquatic habitats, the North Pacific Subtropical Gyre. The project will characterize phytoplankton community composition change and gene expression, photosynthetic performance, carbon fixation, and single-cell level N and C uptake in different taxa within the phytoplankton assemblage in response to different N compounds. The research project is unique in investigating community-to-single-cell level function and species (strain)-specific gene expression patterns using state-of-the-art methods including fast repetition rate fluorometry, nanoscale secondary ion mass spectrometry and a comprehensive marine microbial community microarray. The results will provide predictive understanding of how changes in the availability of key nitrogen pools (N) may impact phytoplankton dynamics and function in the ocean.Broader impacts. This project seeks to understand the ecological basis linking the metabolism of N to phytoplankton biodiversity in the open ocean. The underlying concept that links ecological competition for nutrients (in this case N) to phytoplankton diversity will provide a universal framework for understanding how ecosystem functions are linked to biodiversity. By applying state-of-the-art molecular and genetic methods to address ecological questions, the project seeks to develop an innovative workflow to assess eukaryotic and prokaryotic gene functions in the environment, and provides modern analytical and bioinformatic training for graduate students and postdoctoral researchers. The microarray tool has been designed by involving the larger marine microbiology community and is available to the greater scientific community, and this project is one of the first implementations. The fundamental concepts of microbial ecology and genomics will be used in educational activities in undergraduate and graduate-level classes as well as research training for undergraduates and graduates. Students and the postdoctoral researcher supported by this project will be engaged in development of microbiological and molecular biological displays and presentations at the Exploratorium, a science museum in San Francisco, California. Project personnel will collaboratively develop modules for the Exploratorium. The Exploratorium partnership will provide a mechanism for educational outreach for students and post-docs, as well as an efficient means to communicate the importance of ocean microbes and genomics to the public (over 600,000 visitors per year). The PIs will work with the education team in the Center for Microbial Oceanography: Research and Education (C-MORE) scholars program, at the University of Hawaii, to recruit an undergraduate student to participate in this project. The C- MORE scholars program seeks to promote workforce diversity by identifying faculty mentors to work with students of traditionally underrepresented backgrounds in the STEM disciplines.Integration. This project integrates multiple perspectives on microbial biodiversity. The project seeks to understand how nitrogenous nutrients regulate the taxonomic, genetic, and functional diversity of phytoplankton communities through differential gene expression and functional properties of phytoplankton taxa.