Collaborative Research: Understanding the Role of Picocyanobacteria in the Marine Silicate Cycle

合作研究：了解微微蓝细菌在海洋硅酸盐循环中的作用

• 批准号: 1131788
• 负责人: Jeffrey Krause
• 金额: $ 25.61万
• 依托单位: University of California-Santa Barbara
• 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 2013-05-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1131788&HistoricalAwards=false
• 关键词: Collaborative; Research; Understanding; Role; Picocyanobacteria

INTELECTUAL MERIT: The investigators will follow-up on their discovery of significant accumulation of silicon by marine picocyanobacteria of the genus Synechococcus to assess the contribution of these organisms to the cycling of biogenic silica in the ocean. Oceanographers have long assumed that diatoms are the dominant marine organisms controlling the cycling of silica in the ocean. Recently, however, single-cell analyses of picocyanobacterial cells from field samples surprisingly revealed the presence of substantial amounts of silicon within Synechococcus. The contribution of Synechococcus to biogenic silica often rivaled that of living diatoms in the two systems examined. Moreover, size fractionation of biogenic silica indicates that up to 25% of biogenic silica can exist in the picoplanktonic size fraction. Given that picocyanobacteria dominate phytoplankton biomass and primary production over much of the world?s ocean, these findings raise significant questions about the factors controlling the marine silica cycle globally, as well as the proper interpretation of biogenic silica measurements, Si: N ratios in particulate matter, and ratios of silicate and nitrate depletion. It also suggests that picocyanobacterial populations may be subject to previously unknown constraints on their productivity.The project will have both laboratory and field components. Because cellular Si varies substantially among the field-collected samples and laboratory strains so far analyzed, the laboratory component will document variability in Si uptake and cellular Si concentrations, while determining what role physiological and phylogenetic factors play in this variability. The investigators will use strains of Synechococcus for which there are already genome sequences. Laboratory experiments will 1) use 32Si radiotracer uptake experiments to assess the degree of variability in Si content and Si uptake kinetics among strains of Synechococcus acclimated to different levels of silicate, 2) characterize the intracellular distribution and chemistry of silicon within cells using fractionation techniques, density centrifugation, electron microscopy and x-ray absorption spectroscopy, and 3) use bioinformatic analyses of published genomes to determine whether uptake of Si can be predicted based on phylogenetic relationships, to identify candidate genes involved in cyanobacterial Si metabolism, and to develop probes for community structure that can be related to cellular Si content. Field work at the Bermuda Atlantic Time Series (BATS) site will assess the contribution of Synechococcus and diatoms to total biogenic silica in surface waters at times of the year when the former are typically dominant. Field measurements will include size fractionation of biogenic silica biomass and Si uptake, and synchrotron-based x-ray fluorescence microscopy, and the phylogenetic composition of the Synechococcus assemblage.BROADER IMPACTS: This project has the potential to drive a major paradigm shift in our understanding of the marine silicon cycle. In addition, one PhD student will be trained at Stony Brook. Each PI will provide research experience to a number of undergraduates working on original research projects for credit, as a part of an REU program or as the basis for undergraduate theses. Stony Brook research programs for undergraduates are supported with summer research money from the Undergraduate Research and Creative Activities (URECA) program, and draw on its very diverse student body. The investigators will also engage promising high school level students through several residential programs that the PIs have been a part of in the past. These include the BLOOM program at Bigelow and the Simons Summer Research Fellowship Program at Stony Brook. The PI has continuing relationship with a regional high school (Brentwood) with a high proportion of underrepresented minorities. PI Twining is involved in the Café Scientifique program at Bigelow. Baines will engage in similar outreach through the Center for Science and Mathematics Education (CESAME) sponsored Open Science Nights. Finally, PI Baines will cooperate with CESAMEs teacher education programs, with the aim of incorporating biological oceanography into K-12 curricula. PIs Krause and Brzezinski will incorporate aspects of phytoplankton ecology into UCSB's Oceans to Classroom Program that brings marine research at UCSB to life for over 18,000 K-12 students each year.

实质性优点：研究人员将跟进他们通过属菌群海洋野摩托杆菌大量积累的硅积聚，以评估这些生物体对海洋生物二氧化硅循环的贡献。长期以来，海洋学家一直以为硅藻是控制海洋中二氧化硅循环的主要海洋生物。然而，最近，对田间样品的皮基氨基细胞细胞进行了单细胞分析，令人惊讶地揭示了synechococcus中大量硅的存在。在研究两个系统中，合巨头对生物二氧化硅的贡献经常填充活体硅藻的贡献。此外，生物二氧化硅的尺寸分馏表明，在皮质膨胀尺寸的分数中，最多可以存在多达25％的生物二氧化硅。鉴于皮科摩氏细菌在世界大部分地区占主导地位的浮游植物生物量和初级生产，因此这些发现引发了有关控制全球海洋二氧化硅周期的因素，以及对生物二氧化硅测量的适当解释，SI：N比：nitrate Depletrate depletrate depletrate depletrate depetion si：n比率。这也表明，皮基摩尼生物种群可能受到以前未知的限制，其生产率将具有实验室和现场成分。由于细胞SI在迄今为止分析的现场收集样品和实验室菌株之间有很大的变化，因此实验室成分将记录SI摄取和细胞SI浓度的变异性，同时确定这种变异性在这种变异性中起什么作用生理和系统性因素。研究人员将使用已经存在基因组序列的合巨星菌株。实验室实验将1）使用32SI放射性镜的吸收实验来评估SI含量和SI摄取动力学的可变性程度，在与硅的不同水平相适应的Synechococcus菌株之间，2）表征硅内部的细胞内和化学的硅内分布和化学，利用分流技术，构图，摄影量，密度，密度，密度，密度，密度，密度，密度，量身定为基于量子，并置于量子，并置于密度，二级密度，二进制量。 3）使用对已发表基因组的生物信息学分析来确定是否可以根据系统发育关系来预测SI的吸收，鉴定涉及蓝细菌SI代谢的候选基因，并为可以与细胞SI含量相关的社区结构出现问题。百慕大大西洋时间序列（蝙蝠）部位的现场工作将评估一年中前一年中通常占主导地位的一年中，在地表水中，链球菌和硅藻对总生物二氧化硅的贡献。现场测量将包括生物二氧化硅生物量和SI摄取的尺寸分馏，以及基于同步加速器的X射线荧光显微镜以及Syechocococococcus组合的系统发育组成的影响：该项目有可能使我们对海洋硅周期的理解进行重大范式转移。此外，还将在Stony Brook培训一名博士学位。每个PI都会为许多从事原始研究项目的本科生提供研究经验，作为REU计划的一部分或作为本科论文的基础。本科生研究和创意活动（URECA）计划的夏季研究资金（URECA）计划为本科生的Stony Brook研究计划提供了支持，并借鉴了其非常多样化的学生团体。调查人员还将通过PIS曾经是过去的几个居民计划与有前途的高中学生互动。其中包括Bigelow的Bloom计划和Stony Brook的Simons Summer Research奖学金计划。 PI与一所地区高中（Brentwood）的关系不断，代表性不足的少数民族比例很高。 Pi Twining参与了Bigelow的CaféScientifique计划。贝恩斯将通过科学与数学教育中心（Cesame）进行类似的宣传，赞助了开放科学之夜。最后，Pi Baines将与Cesames教师教育计划合作，目的是将生物海洋学纳入K-12课程。 Pis Krause和Brzezinski将将浮游植物生态学的各个方面纳入UCSB的海洋中，将UCSB的海洋研究带入了每年超过18,000 K-12学生的寿命。