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

知识价值。海洋浮游植物是一种多样的原核和真核单细胞生物，约占全球碳固定的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（亚微摩尔到纳摩尔浓度），通常限制了浮游植物的生长。浮游植物类群在吸收和同化养分方面具有不同的遗传能力，因此对不同化学形式的氮（NH4+、NO3-和尿素）的竞争以及这些含氮化合物的供应是浮游植物生长、生产力和最终生态系统功能的重要控制因素。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，迄今为止，关于氮形态和通量如何影响海洋浮游植物群落组成和初级生产的信息有限。同样，确定响应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、遗传和功能维度与群落水平对不同N基质（NH4+、NO3-和尿素）可用性的响应之间的联系，北太平洋副热带环流是地球上最大的水生栖息地之一。该项目将研究浮游植物群落组成变化、基因表达、光合性能、碳固定和单细胞水平氮碳吸收对不同氮素化合物的响应。该研究项目在研究群落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，使用了最先进的方法，包括快速重复率荧光法、纳米级二次离子质谱法和综合海洋微生物群落微阵列。这些结果将为了解关键氮库(N)可用性的变化如何影响海洋浮游植物的动态和功能提供预测性理解。更广泛的影响。本项目旨在了解开放海洋中N代谢与浮游植物生物多样性之间的生态基础。将营养物（在本例中为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，该项目寻求开发一种创新的工作流程来评估真核和原核基因在环境中的功能，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更大的海洋微生物群落，并可供更大的科学界使用，该项目是首批实施的项目之一。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的教学活动以及本科生和研究生的研究培训。本项目资助的学生和博士后研究员将在加州旧金山的科学博物馆Exploratorium从事微生物学和分子生物学的展示和演讲的开发。项目人员将共同为探索馆开发模块。探索博物馆的合作伙伴关系将为学生和博士后提供教育推广机制，以及向公众（每年超过60万游客）传达海洋微生物和基因组学重要性的有效手段。pi将与夏威夷大学微生物海洋学研究与教育中心（C-MORE）学者计划的教育团队合作，招募一名本科生参加该项目。C- MORE学者计划旨在通过确定教师导师，与STEM学科中传统上代表性不足的背景的学生一起工作，从而促进劳动力多样性。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养分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.