Viral control of microbial communities in Antarctic lakes

病毒在水生环境中普遍存在，一茶匙水中的病毒颗粒可达5亿个。病毒的不断发现似乎证实了目前的认识，即所有形式的生命都可以宿主并被病毒感染，病毒是地球上未开发的遗传多样性的最大储存库之一。本研究旨在更好地了解特定病毒与浮游植物宿主之间的相互作用，并确定这些病毒如何影响南极洲Vestfold Hills湖泊中存在的不同藻类群。这些湖泊（Ace湖、有机湖和深海湖）最初源自海洋，含有多种盐碱化条件，由于数千年来与世隔绝，外部影响很小，因此具有同样广泛的物理化学特征。这些天然实验室允许研究微生物过程和相互作用，这在地球上的其他地方很难描述。该项目将产生广泛的基因组信息，这些信息将免费提供。该项目还将利用病毒研究和基因组方法，在缅因州为高中生开展的一项有组织的非正式教育方案中促进对本科生的培训，并参与和促进对南极科学和微生物研究的了解。通过建立（主要是）特定的dsDNA病毒群在不同季节和年际周期中具有不同氧化还原条件的不同生境中的动态和相互作用，该项目将了解影响微生物群落动态的生物和非生物因素。这个项目不需要在南极洲进行实地考察。相反，调查人员将利用已经收集和存档的三个湖泊的样本，这些样本具有同时测量的物理化学信息。大约2tb的下一代测序（NGS）（包括宏基因组、SSU rRNA扩增子和单病毒基因组）将通过由联合基因组研究所资助的社区科学计划（CSP）从选定的可用样本中生成。研究人员将利用生物信息学来查询这些序列数据库。特别是，他们将重点研究花粉虫、花粉虫样病毒、病毒噬菌体和大dsDNA浮游植物病毒的存在、系统发育和共生，以及它们的真核微生物宿主。生物信息学分析将辅以定量数字PCR和微生物关联网络分析，以检测特定的病毒。从共现空间和时间模式的宿主相互作用。通过多变量分析和网络分析，探讨与三湖浮游植物和病毒丰度最密切相关的非生物因素、时间动态以及观察到的病毒-浮游植物关系。该项目的结果将增进对浮游植物及其病毒作为南极、海洋水生环境以及可能在任何其他水生环境中碳循环的重要组成部分的认识。总的来说，这项工作将促进对独特的南极环境中适应的遗传基础的理解。

Viruses are prevalent in aquatic environments where they reach up to five hundred million virus particles in a teaspoon of water. Ongoing discovery of viruses seems to confirm current understanding that all forms of life can host and be infected by viruses and that viruses are one of the largest reservoirs of unexplored genetic diversity on Earth. This study aims to better understand interactions between specific viruses and phytoplankton hosts and determine how these viruses may affect different algal groups present within lakes of the Vestfold Hills, Antarctica. These lakes (Ace, Organic and Deep)were originally derived from the ocean and contain a broad range of saline conditions with a similarly broad range of physicochemical characteristics resulting from isolation and low external influence for thousands of years. These natural laboratories allow examination of microbial processes and interactions that would be difficult to characterize elsewhere on earth. The project will generate extensive genomic information that will be made freely available. The project will also leverage the study of viruses and the genomic approaches employed to advance the training of undergraduate students and to engage and foster an understanding of Antarctic science and studies of microbes during a structured informal education program in Maine for the benefit of high school students. By establishing the dynamics and interactions of (primarily) specific dsDNA virus groups in different habitats with different redox conditions throughout seasonal and inter annual cycles the project will learn about the biotic and abiotic factors that influence microbial community dynamics. This project does not require fieldwork in Antarctica. Instead, the investigators will leverage already collected and archived samples from three lakes that have concurrent measures of physicochemical information. Approximately 2 terabyte of Next Generation Sequencing (NGS) (including metagenomes, SSU rRNA amplicons and single virus genomes) will be generated from selected available samples through a Community Science Program (CSP) funded by the Joint Genome Institute. The investigators will employ bioinformatics to interrogate those sequence databases. In particular, they will focus on investigating the presence, phylogeny and co-occurrence of polintons, polinton-like viruses, virophages and large dsDNA phytoplankton viruses as well as of their putative eukaryotic microbial hosts. Bioinformatic analyses will be complemented with quantitative digital PCR and microbial association network analysis to detect specific virus?virus?host interactions from co-occurrence spatial and temporal patterns. Multivariate analysis and network analyses will also be performed to investigate which abiotic factors most closely correlate with phytoplankton and virus abundances, temporal dynamics, and observed virus-phytoplankton associations within the three lakes. The results of this project will improve understanding of phytoplankton and their viruses as vital components of the carbon cycle in Antarctic, marine-derived aquatic environments, and likely in any other aquatic environment. Overall, this work will advance understanding of the genetic underpinnings of adaptations in unique Antarctic environments.