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NSFGEO-NERC: An unexpected requirement for silicon in coccolithophore calcification: physiological, ecological and evolutionary implications

NSFGEO-NERC：颗石藻钙化过程中对硅的意外需求：生理、生态和进化影响

基本信息

批准号：
1638838
负责人：
Alison Taylor
金额：
$ 33.52万
依托单位：
University of North Carolina at Wilmington
依托单位国家：
美国
项目类别：
Standard Grant
财政年份：
2016
资助国家：
美国
起止时间：
2016-07-01 至 2022-06-30
项目状态：
已结题

来源：
https://www.nsf.gov/awardsearch/showAward?AWD_ID=1638838&HistoricalAwards=false
关键词：
NSFGEO NERC unexpected requirement silicon

项目摘要

Biomineralization by marine phytoplankton has had a profound impact on our planet. The production of special cell wall material, calcite coccoliths by coccolithophores and silica frustules by diatoms, are major drivers in global biogeochemical cycles, but the underlying cellular processes remain poorly understood. It is widely considered that calcification in coccolithophores occurs through a very different process to silicification in diatoms, however some ecologically important coccolithophore lineages possess diatom-like silicon (Si) transport systems and have an absolute requirement for Si during coccolith formation. Importantly, the abundant bloom-forming coccolithophores such as Emiliania huxleyi exhibit no requirement for Si. There is a clear need to understand how these different physiological requirements for dissolved Si have driven the ecology and evolution of the coccolithophores. The project will yield a more complete understanding of the Si requirements of coccolithophores, its role in the calcification process, and the impacts of Si availability on the biogeography of these important bloom forming phytoplankton. The results are expected to strengthen our ability to predict the responses of coccolithophores to short and long-term environmental change, and therefore the consequences for the marine biogeochemical cycles in which they participate. In addition to the scientific outcomes, the project provides independent research opportunities to a diverse pool of undergraduate students, provide interdisciplinary training for graduate students, and facilitate the professional development of post-doctoral researchers. Public engagement in the research is facilitated through participant involvement in regional science festivals, public outreach events, production of educational resources, and targeted K-12 summer camp activities.Calcification in coccolithophores appears to represent a distinct process from silicification in diatoms, another major group of biomineralized phytoplankton. The apparent absence of a requirement for silicon (Si) in coccolithophores has been proposed to play a critical role in their ability to out-compete the otherwise dominant diatoms in areas of low dissolved Si availability. However, the investigators recently demonstrated that some globally important coccolithophores possess diatom-like Si transporters and exhibit an obligate requirement for Si in the calcification process. This discovery has important implications both for phytoplankton ecology and for the evolution of biomineralization. Using a range of physiological, molecular and computational approaches the project will 1) Establish Si requirements of ecologically important coccolithophore groups; 2) Determine the physiological role of Si in coccolithophores; 3) Determine the evolutionary events leading to the differing requirements for Si in calcification; 4) Examine the ecological distribution of Si-requiring coccolithophores, and 5) Determine the impact of the Si requirement on coccolithophore ecology. This project therefore integrates the molecular identification of genes (Si transporters), the physiological role of these transporters, and ecosystem scale models in order to examine how the requirement for Si influences ecosystem functioning and coccolithophore biogeography. The results of this work provides essential data that describes the cellular mechanisms of calcification and the range of physiological diversity between major coccolithophore lineages. The research also explores a previously unforeseen aspect of phytoplankton ecology; examining how the differing requirements for Si in calcifying coccolithophores may have shaped competitive interactions with other phytoplankton over both contemporary and evolutionary timescales. Overall, the research provides novel insights into physiology, ecology and evolution of coccolithophores, including information on how and why coccoliths are produced, which is currently poorly understood. This information is vital in order to understand how coccolithophores have been influenced by past changes in the Earth's climate, and their potential responses to future oceans.

海洋浮游植物的生物矿化作用对我们的星球产生了深远的影响。特殊的细胞壁材料，球粒石藻的方解石球粒岩和硅藻的硅晶圆体，是全球生物地球化学循环的主要驱动因素，但潜在的细胞过程仍然知之甚少。人们普遍认为，球石藻的钙化过程与硅藻的硅化过程是完全不同的，然而，一些具有重要生态意义的球石藻谱系具有硅藻样的硅（Si）运输系统，并且在球石藻形成过程中对硅有绝对的需求。重要的是，大量形成花的球石藻（如Emiliania huxleyi）不需要Si。很明显，我们需要了解这些对溶解硅的不同生理需求是如何驱动颗石藻的生态学和进化的。该项目将更全面地了解球石藻对硅的需求，其在钙化过程中的作用，以及硅的有效性对这些重要的浮游植物形成华的生物地理学的影响。研究结果将有助于预测球石藻对短期和长期环境变化的响应，从而预测它们所参与的海洋生物地球化学循环的后果。除了科研成果，该项目还为本科生提供独立研究的机会，为研究生提供跨学科培训，并促进博士后研究人员的专业发展。通过参与区域科学节、公共宣传活动、教育资源的生产以及有针对性的K-12夏令营活动，促进了公众对研究的参与。球石藻的钙化过程似乎与硅藻的硅化过程不同，硅藻是另一种主要的生物矿化浮游植物。球石藻对硅（Si）的需求明显缺乏，这在它们在低溶解硅可用性地区与其他占优势的硅藻竞争的能力中发挥了关键作用。然而，研究人员最近证明，一些全球重要的颗石藻具有硅藻样的Si转运体，并且在钙化过程中表现出对Si的强制性需求。这一发现对浮游植物生态学和生物矿化演化具有重要意义。利用一系列生理、分子和计算方法，该项目将1)建立生态上重要的颗石藻群对硅的要求；2)确定Si在球石藻中的生理作用；3)确定导致钙化对Si需求不同的演化事件；4)研究需硅颗石藻的生态分布；5)确定需硅对颗石藻生态的影响。因此，本项目整合了基因（硅转运体）的分子鉴定、这些转运体的生理作用和生态系统尺度模型，以研究对硅的需求如何影响生态系统功能和颗石藻生物地理学。这项工作的结果为描述钙化的细胞机制和主要球石藻谱系之间的生理多样性范围提供了必要的数据。该研究还探索了浮游植物生态学以前无法预见的方面；研究钙化球石藻对硅的不同需求如何在当代和进化时间尺度上形成与其他浮游植物的竞争性相互作用。总的来说，这项研究为球石藻的生理学、生态学和进化提供了新的见解，包括关于球石藻如何以及为什么产生的信息，这些信息目前知之甚少。这些信息对于了解过去地球气候变化对粒石藻的影响以及它们对未来海洋的潜在反应至关重要。

项目成果

期刊论文数量（8）

专著数量（0）

科研奖励数量（0）

会议论文数量（0）

专利数量（0）

An Extracellular Polysaccharide-Rich Organic Layer Contributes to Organization of the Coccosphere in Coccolithophores

富含多糖的细胞外有机层有助于颗石藻中颗球的组织

DOI：
10.3389/fmars.2018.00306
发表时间：
2018
期刊：
Frontiers in Marine Science
影响因子：
3.7
作者：
Walker, Charlotte E.;Heath, Sarah;Salmon, Deborah L.;Smirnoff, Nicholas;Langer, Gerald;Taylor, Alison R.;Brownlee, Colin;Wheeler, Glen L.
通讯作者：
Wheeler, Glen L.

Sr in coccoliths of Scyphosphaera apsteinii: Partitioning behavior and role in coccolith morphogenesis