Dissecting, and revealing the controls on, the group-specific CO2 fixation budget of the Atlantic Ocean

剖析并揭示对大西洋特定群体二氧化碳固定预算的控制

• 批准号: NE/G005141/1
• 负责人: Mikhail Zubkov
• 金额: $ 18.33万
• 依托单位: NATIONAL OCEANOGRAPHY CENTRE
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2009
• 资助国家: 英国
• 起止时间: 2009 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=NE%2FG005141%2F1
• 关键词: Dissecting; revealing; controls; group; specific

The oceans play a major role in determining world climate. In part this is due to the production of oxygen and the consumption of carbon dioxide (CO2) by very small, single celled photosynthetic organisms, the picophytoplankton. Picophytoplankton biomass is dominated by three main groups: the prokaryotic genera Prochlorococcus and Synechococcus, and eukaryotes comprising cells <5 micrometres in size. However, little is known of what goes on inside the picophytoplankton 'black box' particularly with respect to the distribution of carbon biomass and group-specific primary production, information which is fundamental to understanding the roles of these groups in the global C cycle. Very recently our team has optimised utilisation of radiotracer incubation-flow cytometric sorting technology, to reveal group-specific CO2 fixation rates at several stations in the North Atlantic. As well as revealing variability in group-specific CO2 fixation rates between sites this data reiterates the importance of the eukaryotic fraction in primary production estimates (contribution 25-50% dependent on location) even though numerically they are vastly outnumbered by their prokaryotic counterparts. Here, we propose to extend this work so that for the first time we can reveal group-specific CO2 fixation rates at the basin scale, as well as in both surface waters and at the deep chlorophyll maximum (DCM). We will perform this work along an Atlantic Meridional Transect, which traverses the Atlantic Ocean between the UK and the Falkland Islands, and in consecutive years, so that i) a complete group-specific CO2 fixation budget of the Atlantic Ocean is attained and ii) inter-annual variability can be assessed. Moreover, we will examine the precise contribution of different taxonomic lineages to the picoplankton group rates using fluorescent in situ hybridisation of sorted populations and lineage-specific oligonucleotide probes for the prokaryotic genera (Synechococcus and Prochlorococcus) or class-specific probes for the photosynthetic picoeukaryote (PPE) fraction. Hence, this project will provide fundamental information of the major 'players' and routes of CO2 fixation in situ, a process that underpins marine C cycling. Furthermore, we will investigate environmental control of group-specific C fixation rates using on-board bottle experiments following either nutrient addition or shifts in irradiance. This will allow us to understand how environmental perturbation controls the CO2 fixation potential of specific groups. We will couple this latter work with a functional genomics (transcriptomics) approach specifically targeted at the PPE fraction to provide a complementary molecular assessment of the potential regulatory factors controlling this group. This is based on the idea that transcriptional profiling will 'let the organism inform us of the key environmental parameters that these organisms are responding to'. Taken together this work will make major inroads in our understanding of the routes and controls of marine CO2 fixation, information which is essential for a predictive understanding of marine C cycling.

海洋在确定世界气候方面起着重要作用。部分原因是由于非常小的单细胞光合生物（Picophytoplankton）的氧气产生和二氧化碳（CO2）的消耗。 Picophytoplankton生物量主要由三个主要组组成：原核生物属氯环球菌和综合菌，以及包括细胞<5微米的真核生物。然而，鲜为人知的是皮皮纸上的“黑匣子”，特别是在碳生物量和特定于群体特定的初级生产方面发生的事情，这对于理解这些组在全球C周期中的作用至关重要。最近，我们的团队已经优化了对放射性示意剂孵化流动流量分类技术的利用，以揭示北大西洋多个站点的群体特异性二氧化碳固定率。除了揭示位点之间的组特异性二氧化碳固定率的变异性外，该数据还重申了真核分数在初级生产估计中的重要性（贡献了25-50％，取决于位置），即使在数字上它们的原核对应物的数量远远超过了它们。在这里，我们建议扩展这项工作，以便我们首次可以在盆地尺度以及在地表水和深层叶绿素最大值（DCM）上揭示特定组的二氧化碳固定速率。我们将沿着大西洋子午线进行这项工作，该横种横穿英国和福克兰群岛之间的大西洋，并在连续几年内完成大西洋的完整群体特异性二氧化碳预算，并获得了ii），可以评估年间可变性。此外，我们将使用荧光原位杂交对原位种群的原位杂交和谱系特异性的寡核苷酸探针进行原位杂交（synechococcus and proCococcus）或类别探针的谱系探针，以探讨不同分类学谱系对皮皮普兰克顿组速率的精确贡献。因此，该项目将提供主要“玩家”的基本信息和原位二氧化碳固定路线，这是海上C骑自行车的基础的过程。此外，我们将使用营养添加或辐照度转移后使用板载瓶实验研究组特异性C固定速率的环境控制。这将使我们能够了解环境扰动如何控制特定组的二氧化碳固定潜力。我们将把后者的工作与专门针对PPE分数的功能基因组学（转录组学）方法相结合，以提供控制该组的潜在调节因素的互补分子评估。这是基于这样的想法：转录分析将“让生物体向我们告知这些生物正在响应的关键环境参数”。综上所述，这项工作将使我们对海洋二氧化碳固定的途径和控制的理解大大介绍，这对于对海洋C自行车的预测理解至关重要。

项目成果

Faster growth of the major prokaryotic versus eukaryotic CO2 fixers in the oligotrophic ocean.

• DOI: 10.1038/ncomms4776
• 发表时间: 2014-04-29
• 期刊: NATURE COMMUNICATIONS
• 影响因子: 16.6
• 作者: Zubkov, Mikhail V.