Collaborative Research: Iron Bioavailability in High-CO2 Oceans: New Perspectives on Iron Acquisition Mechanisms in Diatoms

合作研究：高二氧化碳海洋中的铁生物利用度：硅藻中铁获取机制的新视角

• 批准号: 1756860
• 负责人: Katherine Barbeau
• 金额: $ 42.1万
• 依托单位: University of California-San Diego Scripps Inst of Oceanography
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2018
• 资助国家: 美国
• 起止时间: 2018-02-15 至 2023-01-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1756860&HistoricalAwards=false
• 关键词: Collaborative; Research; Iron; Bioavailability; CO2

Collaborative Research: Iron Bioavailability in High-CO2 Oceans: New Perspectives on Iron Acquisition Mechanisms in DiatomsIron is critically needed for growth of all marine phytoplankton, the microscopic plants at the base of the ocean food chain. Consequently, lack of iron in large regions of the global ocean limits phytoplankton growth and commercial fisheries. Ocean acidification (OA) is the ongoing decrease in seawater pH due to the ocean absorbing carbon dioxide from the atmosphere. OA is predicted to affect seawater chemistry by reducing the concentration of carbonate ions. Carbonate ions are required for phytoplankton to take up iron from their environment, which suggests that OA might inhibit iron nutrition. Further complicating the scenario, pH changes affect iron chemistry in seawater, such that OA is predicted to shift the relative abundance of various forms of iron. But despite these expectations, little is known about how the changes in ocean chemistry due to OA will impact the availability of iron to phytoplankton. Changes in phytoplankton iron uptake and associated growth rates would likely have large effects on how the ocean captures atmospheric carbon dioxide (CO2). This has important consequences for ecosystem productivity and for global cycles of critical chemical elements, such as carbon and nitrogen, and their chemistry. This project aims to help us understand how shifts in seawater pH and the chemistry of dissolved inorganic carbon will affect both iron uptake rates and iron acquisition strategies in the laboratory and in natural communities. This project also includes development of educational outreach activities which target primary school students in the areas of microbiology, biogeochemical cycles and current global change topics. These science outreach activities benefit from collaborations with the following San Diego-based organizations: the League of Extraordinary Scientists and Engineers (LXS), The Birch Aquarium at Scripps (BAS), and The Ocean Discovery Institute (ODI).This project seeks to understand the differential sensitivity of diatom iron acquisition strategies to changes in seawater pH and carbonate chemistry. Ultimately a more thorough and detailed mechanistic understanding of diatom iron uptake pathways will facilitate a much-improved ability to forecast the impact of anticipated changes in ocean pH and inorganic carbon chemistry on rates of iron uptake by diatoms. This critical biogeochemical issue is addressed through trace metal clean manipulation experiments incorporating state-of-the-art analytical methodology to probe phytoplankton cellular physiology and biogeochemistry in laboratory cultures and natural communities. In the first year, laboratory experiments with a model pennate diatom leverage a collection of targeted knockout transgenic lines to evaluate the substrate specificity and relative importance of distinct iron assimilation pathways under a range of pCO2 and iron availability conditions. Additionally, quantitation of mRNA and proteins for key diatom iron assimilation pathways in natural communities in the Southern California Current further clarify the relative importance and sensitivity of distinct iron assimilation pathways in relation to pCO2 and iron availability. In year two a Lagrangian study of iron uptake rates and associated mRNA and protein abundance is performed on upwelled high pCO2 water over the course of offshore advection. Additionally, the investigators are conducting mesocosm experiments using naturally elevated high pCO2 seawater as well as laboratory experiments on multiplex knockout lines. Year three is dedicated to data analyses and overall project synthesis. Overall aims of the research activities include, 1) development and validation of a refined conceptual model of iron uptake in key marine phytoplankton and subsequent utilization of the model to characterize the sensitivity of distinct iron uptake pathways to the effects of ocean acidification, and 2) determination of the effects of acidification on iron uptake, and quantification of the relative contribution of distinct iron acquisition pathways in high pCO2 phytoplankton communities.

协作研究：高CO2海洋中的铁生物利用度：对所有海洋浮游植物的生长至关重要的是硅藻中的铁的新观点，这是所有海洋浮游植物的生长，这是海洋食物链底部的微观植物。因此，在全球海洋的大区域中缺乏铁，会限制浮游植物的生长和商业渔业。海洋酸化（OA）是由于海洋吸收二氧化碳从大气中吸收的海水pH值持续下降。预计OA会通过降低碳酸盐离子的浓度来影响海水化学。浮游植物需要碳酸盐离子从其环境中取走铁，这表明OA可能会抑制铁营养。进一步使情况复杂化，pH变化会影响海水中的铁化学，因此预计OA会改变各种形式的铁的相对丰度。但是，尽管有这些预期，但对于OA引起的海洋化学变化将如何影响铁对浮游植物的可用性，知之甚少。浮游植物铁的摄取和相关生长速率的变化可能会对海洋捕获大气二氧化碳（CO2）的影响很大。这对生态系统的生产力以及关键化学元素的全球周期（例如碳和氮及其化学元素）具有重要的后果。该项目旨在帮助我们了解海水pH的转变和溶解的无机碳的化学如何影响实验室和自然社区中的铁吸收率和铁获取策略。该项目还包括开发教育外展活动，这些活动针对小学生在微生物学，生物地球化学周期和当前的全球变化主题方面。这些科学宣传活动受益于与以下总部位于圣地亚哥的组织的合作：非凡的科学家和工程师联盟（LXS），Scripps（BAS）的桦木水族馆和海洋发现研究所（ODI）。该项目旨在了解Diotom Iracition Cartiesition Cartistion for Seatwater Ph和Cherbonate Chemanterate Chemanterate Chemanters Chemical ph和Carbonate Chemical ph和碳化化学的变化。最终，对硅藻铁吸收途径的更彻底，更详细的机理理解将有助于预先改进的能力，以预测海洋pH和无机碳化学对硅铁摄取率的预期变化的影响。通过痕量金属清洁操纵实验解决了这个关键的生物地球化学问题，该实验将最先进的分析方法探测到实验室培养和自然社区中的浮游植物细胞生理学和生物地球化学。在第一年，使用模型甲酸盐硅藻的实验室实验利用了目标敲除转基因线的集合来评估在PCO2和铁可用性条件下不同铁同化途径的底物特异性和相对重要性。另外，对南加州自然界的关键硅藻铁同化途径的mRNA和蛋白质的定量进一步阐明了与PCO2和铁的可用性相关的不同铁同化途径的相对重要性和敏感性。在第二年，在近海平流过程中，在上流的高PCO2水上进行了对铁吸收率以及相关的mRNA和蛋白质丰度的拉格朗日研究。此外，研究人员正在使用自然升高的高PCO2海水以及多路复用敲除线上的实验室实验进行中验实验。 三年级致力于数据分析和整体项目综合。研究活动的总体目的包括，1）在关键海洋浮游植物中的铁吸收概念模型的开发和验证，以及随后对模型的利用来表征不同铁吸收途径对海洋酸化影响的敏感性，以及2）对酸化对铁的影响和量子对铁的影响的确定2）社区。

项目成果

Carbonate-sensitive phytotransferrin controls high-affinity iron uptake in diatoms

• DOI: 10.1038/nature25982
• 发表时间: 2018-03-22
• 期刊: NATURE
• 影响因子: 64.8
• 作者: McQuaid, Jeffrey B.;Kustka, Adam B.;Allen, Andrew E.
• 通讯作者: Allen, Andrew E.

Reduction-dependent siderophore assimilation in a model pennate diatom

• DOI: 10.1073/pnas.1907234116
• 发表时间: 2019-11-19
• 期刊: PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
• 影响因子: 11.1
• 作者: Coale, Tyler H.;Moosburner, Mark;Allen, Andrew E.
• 通讯作者: Allen, Andrew E.