Regulation of amino acid uptake in marine unicellular cyanobacteria: light sensing and circadian clocks.

海洋单细胞蓝细菌氨基酸摄取的调节：光传感和生物钟。

• 批准号: NE/C514723/1
• 负责人: Mikhail Zubkov
• 金额: $ 3.89万
• 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: 2006
• 资助国家: 英国
• 起止时间: 2006 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=NE%2FC514723%2F1
• 关键词: Regulation; amino; acid; uptake; marine

Cyanobacteria numerically dominate the tropical and subtropical regions of the world's oceans with Prochlorococcus being the dominant photosynthetic organism of the open ocean and Synechococcus dominating in oceanic boundaries at low latitudes. Recently it was observed that Prochlorococcus shows a pronounced diel (day-night) periodicity in uptake of dissolved amino acids compared to Synechococcus. These field observations have important ecological implications. For example in the tropical Atlantic Ocean the Prochlorococcus population contributes around 10% and 40% to the total bacterioplankton uptake of amino acids at midday and after dusk, respectively and therefore exerts a considerable pressure on other bacterioplankton populations by consuming a significant proportion of organic nitrogen in already nutrient-depleted oceanic waters. However, field observations alone are insufficient to understand the mechanism regulating organic nutrient uptake. To address this we propose to study this process using cyanobacterial cultures grown in controlled laboratory conditions and to test the hypothesis that the uptake of amino acids, and possibly other organic nitrogen containing compounds, by Prochlorococcus could be regulated either by light and/or a circadian clock. To do this we will use a combination of isotopic tracer and flow cytometric techniques. The cyanobacterial strains will be exposed to various light regimes (varying in quality, quantity, periodicity), loaded with isotopically-labelled precursor molecules, and the cells at various cell cycle stages will be flow sorted to determine cellular uptake rates of the isotopic tracers. The research team for this project will have a unique combination of expertise with marine skills in microbial biogeochemistry, flow cytometry, molecular ecology of cyanobacteria combined with terrestrial background skills in plant photobiology. All necessary capital equipment is available.

蓝藻在数量上主导着世界海洋的热带和亚热带地区，其中原氯球菌是开放海洋的主要光合作用有机体，聚球藻在低纬度的海洋边界占主导地位。最近观察到，与聚球藻相比，原氯球菌对溶解氨基酸的摄取具有明显的昼夜周期性。这些野外观测具有重要的生态学意义。例如，在热带大西洋，原氯球菌种群在中午和黄昏后分别占浮游细菌总氨基酸摄取量的10%和40%左右，因此在已经耗尽营养物质的海洋水域中消耗了相当大比例的有机氮，对其他浮游细菌种群施加了相当大的压力。然而，仅靠田间观察还不足以了解有机养分吸收的调控机制。为了解决这个问题，我们建议使用在受控实验室条件下生长的蓝藻培养物来研究这一过程，并检验原氯球菌对氨基酸的吸收，以及可能包含其他有机氮化合物的假设，可以受光和/或生物钟调节。为了做到这一点，我们将使用同位素示踪和流式细胞仪技术的组合。蓝藻菌株将暴露在不同的光照条件下(质量、数量、周期不同)，负载有同位素标记的前体分子，并对处于不同细胞周期阶段的细胞进行流动分选，以确定细胞对同位素示踪剂的摄取速率。该项目的研究团队将拥有微生物生物地球化学、流式细胞术、蓝藻分子生态学方面的海洋技能与植物光生物学的陆地背景技能的独特结合。所有必要的资本设备都可用。