Opening the black box of viruses in aquatic systems

病毒的丰度为106至108毫升-1，是海洋中数量最多、种类最多的“生命”。首尾相连，它们将延伸107光年，比最近的60个星系还要远。据估计，它们感染约1023个细胞s-1，每天杀死10%至20%的海洋生物量，导致浮游植物固定的6%至26%的碳通过病毒分流。显然，病毒是死亡率、营养循环和构建水生生物群落的主要参与者;然而，病毒在水生系统中的组成和功能在很大程度上是未知的。我研究的长期目标是了解水生病毒的巨大遗传和生物多样性及其对生态系统的影响。拟议的研究将通过病毒发现和量化它们对死亡率的影响来促进我们对水生病毒及其功能的理解。** 在病毒发现主题中，传统方法将用于分离感染生态重要类群的新型病毒，而最先进的单病毒体基因组和宏基因组方法将用于表征分离株和原位病毒群落。四个项目包括病毒发现部分：1）分离和表征新的宿主病毒系统的生态重要的微生物类群将提供模型系统研究宿主病毒的相互作用。我们将重点关注巨型病毒，因为宏基因组数据表明它们在水生系统中广泛存在，但在培养中很少感染浮游原生生物。2)我们将采用单病毒体基因组技术对来自一系列自然环境的未培养的代表性病毒进行测序。这将有助于关闭水生病毒的序列空间，并为短读宏基因组数据提供基因组背景。3)水生RNA病毒群落的宏基因组分析将揭示一系列水生系统中最丰富的RNA病毒，允许组装新的基因组，并为其他研究的靶向扩增子测序数据提供背景。4)确定与浮游动物主要类群相关的病毒的组成及其潜在影响。第二个主题探讨了病毒对微生物死亡率的影响。使用靶向测序技术来估计跨系统的分类群特异性病毒介导的死亡率，我们将确定哪些原核和真核微生物分类群最容易发生病毒裂解，并测试大多数裂解发生在生产性但相对罕见的社区成员中的假设。总的来说，这项研究计划通过将新的病毒宿主系统引入培养，表征病毒群落和确定微生物群落中的分类特异性裂解来促进我们对水生系统中病毒的理解。

At abundances of 106 to 108 ml-1, viruses are the most numerous and diverse "life" in the oceans. End-to-end, they would stretch 107 light years, farther than the nearest 60 galaxies. It is estimated they infect ~1023 cells s-1, and kill 10 to 20% of the ocean's biomass daily, resulting in 6 to 26% of carbon fixed by phytoplankton passing through the viral shunt. Clearly, viruses are major players in mortality, nutrient cycling and structuring planktonic communities; yet, the composition and function of viruses in aquatic systems is largely unknown. The long-term goal of my research is to understand the enormous genetic and biological diversity of aquatic viruses and their impact on ecosystems. The proposed research will advance our understanding of aquatic viruses and their function through virus discovery and quantifying their impact on mortality. ******In the virus-discovery theme, traditional approaches will be used to isolate novel viruses that infect ecologically important taxa, while state-of-the-art single-virion genomic and metagenomic approaches will be employed to characterize the isolates and in situ virus communities. Four projects comprise the viral discovery component: 1) Isolation and characterization of new host-virus systems for ecologically important microbial taxa will provide model systems for studying host-virus interactions. We will focus on giant viruses, because metagenomic data indicate they are widespread in aquatic systems, but there are few in culture infecting planktonic protists. 2) We will employ single-virion genomic technologies to sequence uncultured representative viruses from a range of natural environments. This will help close the sequence space for aquatic viruses and provide genomic context for short-read metagenomic data. 3) Metagenomic analysis of aquatic RNA virus communities will reveal the most abundant RNA viruses across a range of aquatic systems, allow the assembly of novel genomes, and provide context to targeted amplicon sequencing data from other studies. 4) Determining the composition of viruses associated with major taxa of zooplankton and their potential impact.******The second theme explores the impact of viruses on microbial mortality. Using a targeted sequencing technique to estimate taxon-specific viral mediated mortality across systems we will determine which prokaryotic and eukaryotic microbial taxa are most subject to viral lysis, and test the hypothesis that most lysis is occurring in productive but relatively rare members of the community.******Collectively, this research program advances our understanding of viruses in aquatic systems by bringing new virus-host systems into culture, characterizing viral communities and determining taxon-specific lysis in microbial communities.