Protistan grazing and viral infection of marine picoplankton: a role for the host cell surface?

海洋超微型浮游生物的原生生物放牧和病毒感染：宿主细胞表面的作用？

• 批准号: NE/J020745/1
• 负责人: Mikhail Zubkov
• 金额: $ 9.29万
• 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: 2012
• 资助国家: 英国
• 起止时间: 2012 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=NE%2FJ020745%2F1
• 关键词: Protistan; grazing; viral; infection; marine

The oceans play a major role in determining the world's climate. In part this is due to the production of oxygen and the consumption of carbon dioxide by very small, single celled organisms, which are referred to as the photosynthetic picoplankton. Marine cyanobacteria of the closely-related genera Prochlorococcus and Synechococcus are the prokaryotic components of the photosynthetic picoplankton. These cyanobacteria are continually growing and dividing, but they are also continuously being consumed. There are two major processes that contribute to the consumption of these cells. Firstly, they can be infected and killed by viruses and secondly they can be used as food by small single celled grazing animals called protists. It is the interaction between these two processes of mortality, together with the defence mechanisms that the cyanobacteria have developed, which are the focus of this research project. We recently observed that a marine Synechococcus strain that was infected with a virus was more susceptible to grazing than the uninfected culture. This distinct preference for preying on phage-infected cells has potentially important ecological implications, as it interferes with phage proliferation by removing infected cells before they burst and could thus indirectly reduce phage abundance. It is not yet clear what determines the palatability of a prey cell. Cell surface properties are likely to play a role and we have preliminary evidence that lipopolysaccharide (LPS) components of the cell wall are critical in this respect. This proposal will thus compare protist feeding on virus-infected, uninfected and LPS-modified Synechococcus strains in order to specifically elucidate the role of LPS in prey digestibility. Moreover, we will extend our studies to the Atlantic Ocean to investigate whether cultured protists graze differentially on natural Synechococcus populations, and in so doing establish the role of strain selectivity, or preference for cyanophage-infected cells, in this processOverall, the project will provide fundamentally new mechanistic information on the major biological loss processes that dictate the growth rate and yield of a key marine photoautotroph, information which is critical for defining and understanding controls on marine photosynthesis.

海洋在决定世界气候方面发挥着重要作用。这部分是由于非常小的单细胞生物产生氧气和消耗二氧化碳，这些生物被称为光合微型浮游生物。海洋蓝细菌的密切相关的属原绿球藻和聚球藻是光合微型浮游生物的原核组成部分。这些蓝藻不断生长和分裂，但它们也不断被消耗。有两个主要过程有助于这些细胞的消耗。首先，它们可以被病毒感染和杀死，其次，它们可以被称为原生生物的小型单细胞食草动物用作食物。这是这两个死亡过程之间的相互作用，以及蓝细菌已经开发的防御机制，这是本研究项目的重点。我们最近观察到，海洋聚球藻菌株感染了病毒比未感染的文化更容易放牧。这种对噬菌体感染细胞的明显偏好具有潜在的重要生态意义，因为它通过在感染细胞破裂之前去除感染细胞来干扰噬菌体增殖，从而间接降低噬菌体丰度。目前还不清楚是什么决定了被捕食细胞的适口性。细胞表面性质可能发挥作用，我们有初步证据表明，细胞壁的脂多糖（LPS）成分在这方面是至关重要的。因此，该建议将比较原生动物喂养病毒感染，未感染和LPS修饰的聚球藻菌株，以具体阐明LPS在猎物消化率中的作用。此外，我们将把我们的研究扩展到大西洋，以调查培养的原生生物是否差异地吃天然聚球藻种群，并在此过程中建立菌株选择性的作用，或对噬藻体感染细胞的偏好。总体而言，该项目将提供关于主要生物损失过程的全新机制信息，这些生物损失过程决定了关键海洋光合自养生物的生长速率和产量，这些信息对于定义和理解海洋光合作用的控制至关重要。

项目成果

Targeted genomics of flow cytometrically sorted cultured and uncultured microbial groups.

通过流式细胞术分类的培养和未培养微生物群的靶向基因组学。

• DOI: 10.1007/978-1-62703-712-9_16
• 发表时间: 2014
• 期刊: Methods in molecular biology (Clifton, N.J.)
• 作者: Mazard S