Who are the ubiquitous, biomass-significant red fluorescent picoplanktonic cells in temperate and polar surface oceans?

谁是温带和极地表层海洋中普遍存在的、生物量显着的红色荧光超微型浮游细胞？

• 批准号: NE/H010572/1
• 负责人: Mikhail Zubkov
• 金额: $ 6.2万
• 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: 2010
• 资助国家: 英国
• 起止时间: 2010 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=NE%2FH010572%2F1
• 关键词: Who; ubiquitous; biomass; significant; red

The aim of the proposal is to identify the cells comprising the extra red fluorescence group of large bacterioplankton and to ascertain their metabolic potential. We propose to test a hypothesis that these red fluorescent cells are aerobic anoxygenic phototrophic bacterioplankton (AAPs) containing bacteriochlorophylls. Previous studies show that AAPs lack autotrophic inorganic carbon assimilation pathways and are incapable of photoautotrophy, relying on heterotrophy for the majority of their cellular energetics. However, our provisional measurements of 3H-leucine and 35S-methionine uptake by the red fluorescent cells suggested that the uptake rates of both amino acids by these cells, although being higher than the uptake rates by Synechococcus phototrophic cyanobacteria, are considerably lower than the amino acid uptake rates by mean heterotrophic bacterioplankton cells. Therefore, the red fluorescent cells probably harvest light to photochemically oxidise organic molecules in order to sustain their sizeable ubiquitous population in the photic temperate and polar ocean. The project proposes (i) to phylogenetically affiliate cells, flow cytometrically sorted from the extra red fluorescence group of large bacterioplankton; (ii) to design and test specific oligonucleotide probes for identification of flow sorted cells; to examine the presence of bacteriochlorophyll genes in flow sorted cells; (iii) to examine latitudinal variations in phylogenetic composition of the red fluorescence group. In order to meet the above objectives we will focus on molecular analysis of samples collected in the Atlantic Ocean, where these microorganisms were first observed. Our ultimate goal is to explain their ecological role in oceanic ecosystems.

该提案的目的是识别包含大型浮游细菌的额外红色荧光组的细胞，并确定它们的代谢潜力。我们建议检验一个假设，即这些红色荧光细胞是含有细菌叶绿素的需氧无氧光养浮游细菌（AAP）。先前的研究表明，AAP 缺乏自养无机碳同化途径，并且不能进行光自养，其大部分细胞能量依赖于异养。然而，我们对红色荧光细胞摄取 3H-亮氨酸和 35S-甲硫氨酸的临时测量表明，这些细胞对这两种氨基酸的摄取率虽然高于聚球藻光养蓝藻的摄取率，但远低于平均异养浮游细菌细胞的氨基酸摄取率。因此，红色荧光细胞可能会收集光来对有机分子进行光化学氧化，以维持其在光温带和极地海洋中大量普遍存在的种群。该项目建议（i）在系统发育上附属细胞，通过流式细胞术从大型浮游细菌的额外红色荧光组中分类； (ii) 设计和测试用于鉴定流式分选细胞的特定寡核苷酸探针；检查流式分选细胞中细菌叶绿素基因的存在； (iii) 检查红色荧光组的系统发育组成的纬度变化。为了实现上述目标，我们将重点对在大西洋收集的样本进行分子分析，这些微生物是在大西洋首次观察到的。我们的最终目标是解释它们在海洋生态系统中的生态作用。