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PUCCA: Photosynthetic Underpinnings of Coccolithophore CAlcification

PUCCA：颗石藻钙化的光合基础

基本信息

批准号：
NE/V011049/1
负责人：
Rosalind Emily Mayors Rickaby
金额：
$ 208.73万
依托单位：
University of Oxford
依托单位国家：
英国
项目类别：
Research Grant
财政年份：
2021
资助国家：
英国
起止时间：
2021 至无数据
项目状态：
未结题

来源：
https://gtr.ukri.org/projects?ref=NE%2FV011049%2F1
关键词：
PUCCA Photosynthetic Underpinnings Coccolithophore CAlcification

项目摘要

Coccolithophores generate over 1 billion tonnes of calcium carbonate every year in the ocean. This calcium carbonate is a foundation of marine ecosystem and the ocean carbon cycle. The generation of calcium carbonate in the surface ocean affects how much CO2 dissolves in those surface waters from the atmosphere. And the added density of calcium carbonate in the plankton and sinking marine particulate matter helps it drop to depth enhancing the transport of carbon dioxide from surface waters (and so the atmosphere) to the deep ocean. Despite the enormous production rate of calcium carbon and its central importance in controlling how much carbon dioxide reaches the deep ocean, there is currently no answer to the question of what limits marine calcification and how this component of the ocean carbon budget will change into the future. There has been much concern regarding the impact of ocean acidification on the ability of marine calcifiers to produce their shells. All current ocean carbon cycle models infer calcite production rates according to an equation which depends only on the calcite saturation state, which diminishes with acidification, of the form Calcification rate = (1-saturation)^n. But the current ocean is four times supersaturated with respect to calcite so saturation state cannot be the only parameter limiting calcification rates. All marine calcifiers are fueled by sunlight and photosynthesis, with the coccolithophores containing a chloroplast from an ancient secondary endosymbiotic event. So the process of calcification by an organism has two sides to the equation: the energy and carbon that is available to invest in calcification and the energetic and carbon cost of calcification. PUCCA aims to uncover how the environment controls both sides of the equation and their coupling, namely how the energy available from photosynthesis is partitioned between cell growth and calcification. The importance of photosynthesis to these organisms is underlined by the observation that when these cells evolved the ability to calcify in the Mesozoic, they coincidentally lost their ability to feed on any other source of carbon and became fully dependent on photosynthesis, or autotrophic.The ability to succeed in an environment is determined by an organism's growth rate under conditions of resource limitation. PUCCA aims to document and generate a mechanistic understanding at the molecular, cell and community level, of how environmental change selects for different coccolithophore strategies of cell resource allocation between photosynthesis, calcification and growth. PUCCA will use the geological record and modern ocean as a natural laboratory to show how evolution has selected for these traits over the 60 million year history of climate and across the latitudes of the modern ocean. For the first time there are sufficient strains of a single species, Emiliania huxleyi, isolated from across the world's oceans and with diverse calcification phenotypes, to obtain candidates for key calcification and photosynthetic genes and to identify the metabolic pathways linking photosynthetic products with calcification and their efficiency. This unique library of near genetically identical isolates also allows a detailed investigation of the biochemical basis for differing cellular resource allocation between photosynthesis and calcification which underpins the diverse phenotypes. PUCCA will test how these biochemical strategies function over time and leave an imprint in the geological record by developing cutting edge techniques for the extraction and characterisation of metabolites from the fossil record. Our results will transform predictions of the coccolithophore calcification response to global change in the future and will generate a novel, mechanistically grounded, parameterisation of marine calcite production to implement into models of the past and future carbon cycles.

球石生物每年在海洋中产生超过10亿吨的碳酸钙。这种碳酸钙是海洋生态系统和海洋碳循环的基础。表层海洋中碳酸钙的生成会影响大气中二氧化碳在表层海水中的溶解程度。浮游生物中增加的碳酸钙密度和下沉的海洋颗粒物有助于其下沉到深处，促进二氧化碳从表层水域(以及大气)向深海的运输。尽管钙碳的产量巨大，在控制到达深海的二氧化碳数量方面具有核心作用，但目前还没有答案来回答是什么限制了海洋钙化，以及海洋碳收支的这一组成部分在未来将如何变化。关于海洋酸化对海洋钙化物产生贝壳能力的影响，人们有很大的关注。目前所有的海洋碳循环模型都是根据方解石的饱和状态(钙化率=(1-饱和)^n)来推算方解石的产率，但目前的海洋是方解石的四倍过饱和状态，因此饱和状态不是限制钙化速率的唯一参数。所有的海洋钙化物都是由阳光和光合作用提供能量的，球藻中含有一种来自古代次生内共生事件的叶绿体。因此，生物体的钙化过程有两个方面：可用于钙化的能量和碳，以及钙化的能量和碳成本。Pucca的目标是揭示环境如何控制等式的两边以及它们之间的耦合，即光合作用可用能量是如何在细胞生长和钙化之间分配的。当这些细胞在中生代进化出钙化能力时，它们巧合地失去了以任何其他碳来源为食的能力，完全依赖光合作用或自养作用，这一观察突显了光合作用对这些生物的重要性。在环境中取得成功的能力取决于有机体在资源有限的条件下的生长速度。PUCA的目标是在分子、细胞和群落层面记录和产生一种机械性的理解，即环境变化如何为光合作用、钙化和生长之间的细胞资源分配的不同球虫策略做出选择。PUCA将使用地质记录和现代海洋作为自然实验室，展示在6000万年的气候历史和现代海洋的纬度上，进化是如何选择这些特征的。首次有足够的单个物种的菌株，从世界各地的海洋分离出来，具有不同的钙化表型，以获得关键的钙化和光合作用基因的候选者，并确定将光合作用产物与钙化及其效率联系起来的代谢途径。这种独特的、在遗传上几乎相同的菌株文库还可以详细研究光合作用和钙化作用之间不同细胞资源分配的生化基础，这是不同表型的基础。PUCA将测试这些生化策略如何随着时间的推移发挥作用，并通过开发从化石记录中提取和表征代谢物的尖端技术在地质记录中留下印记。我们的结果将改变对未来全球变化的球石生物体钙化反应的预测，并将产生一种新颖的、机械地基于海洋方解石生产的参数化，以实施到过去和未来碳循环的模型中。

项目成果

期刊论文数量（10）

专著数量（0）

科研奖励数量（0）

会议论文数量（0）

专利数量（0）

Evaluation of the effect of calcification intensity on the isotopical composition of coccolith calcite

钙化强度对球石方解石同位素组成影响的评价

DOI：
10.5194/egusphere-egu23-16355
发表时间：
2023
期刊：
影响因子：
0
作者：
Gonzalez-Lanchas A
通讯作者：
Gonzalez-Lanchas A

Rapid diversification underlying the global dominance of a cosmopolitan phytoplankton.

DOI：
10.1038/s41396-023-01365-5
发表时间：
2023-04
期刊：
ISME JOURNAL
影响因子：
11
作者：
Bendif, El Mahdi;Probert, Ian;Archontikis, Odysseas A.;Young, Jeremy R.;Beaufort, Luc;Rickaby, Rosalind E.;Filatov, Dmitry
通讯作者：
Filatov, Dmitry

Globally enhanced calcification across the coccolithophore Gephyrocapsa complex during the mid-Brunhes interval

DOI：
10.1016/j.quascirev.2023.108375
发表时间：
2023-12
期刊：
Quaternary Science Reviews
影响因子：
4
作者：
A. González-Lanchas;R. Rickaby;F. Sierro;A. Rigual-Hernández;M. Alonso-García;José A. Flores
通讯作者：
A. González-Lanchas;R. Rickaby;F. Sierro;A. Rigual-Hernández;M. Alonso-García;José A. Flores

Changes in coccolithophore calcification intensity in the modern ocean: implications for the isotopical composition of coccolith calcite

现代海洋中颗石藻钙化强度的变化：对颗石方解石同位素组成的影响