Collaborative Research: Lipid lubrication of oceanic carbon and sulfur biogeochemistry via a host-virus chemical arms race

智力优势：尽管病毒在塑造海洋微生物生态系统中至关重要，但对介导植物毒素-病毒相互作用的分子机制知之甚少。因此，我们目前缺乏生物标志物来量化海洋中活跃的病毒感染，这严重阻碍了我们对其生态和地球化学影响的理解。球石藻Emiliania huxleyi（Prymnesiophyceae，Haptophyte）是一种世界性的单细胞光合自养生物，其方解石骨架约占海洋碳酸钙总产量的三分之一。E.赫胥黎在北大西洋每年春季大量开花，被含有球石病毒的裂解性巨大双链DNA感染并终止。结果表明，溶菌性病毒感染E. huxleyi招募宿主程序性细胞死亡（PCD）机制证明，病毒采用了一种复杂的，共同进化的？军备竞赛？介导宿主与病毒的相互作用。研究人员最近证明，来自意外的鞘脂生物合成基因簇的病毒鞘糖脂（vGSL），这是一种从未在病毒基因组中描述过的途径，在促进E. huxleyi。在北大西洋和挪威峡湾的vGSL的观察进一步表明，它们可能是新的，诊断的生物标志物的病毒感染的颗石藻种群。同时，vGSL和一种独特的保护性802脂质的发现表明，宿主-病毒，共同进化的化学军备竞赛在调节病毒感染和润滑C和S的上层海洋生物地球化学通量中起着关键作用。该项目的重点是阐明vGSL（和其他极性脂质）与全球碳和硫循环之间的分子，生态和生物地球化学联系。研究小组提出了一种多管齐下的方法，将一系列基于实验室的机制研究与东北大西洋的观察性研究和操纵性实地实验结合起来，这些研究使用了几种接触菌-病毒模型系统沿着。使用这些诊断标记，他们将记录自然颗石藻种群的活跃病毒感染，并将其与一系列海洋学测量相结合，以量化病毒感染如何影响海洋环境。（通过vGSL）影响细胞命运、溶解有机碳（DOC）库、特定有机碳（POC）和无机碳的垂直输出（PIC;作为碳酸钙，CaCO 3）（沿着相关的烯酮脂质生物标志物和病毒及其宿主的遗传特征）和上层海洋硫循环（通过二甲基硫[DMS]和其他生物硫化合物的循环）。此外，鉴于它们是病毒所独有的，他们提出vGSL可用于追踪病毒衍生碳的流动，并提供定量的见解？病毒分流从高营养层和深海转移固定碳。这项研究的首要假设是，vGSL是上层海洋的基石分子，它促进了大规模的病毒感染，从而在机制上？润滑剂？更广泛的影响：这项研究融合了生理学、分子生物学、生物化学、病毒学和脂质化学的概念，以及海洋学和海洋地球化学，从而提供了一个机会，使具有不同教育背景的研究人员能够相互交流和发展。该项目为博士后、研究生和本科生的发展提供了良好的实践培训。该研究为机构间交流提供了资源和机会Rutgers-WHOI-查尔斯顿学院，并建立在现有的国家和国际合作的基础上，并将促进新的合作。PI现在将与COSEE合作，网络海洋世界？通过将科学研究与K-12教育工作者和公众相结合，提高海洋素养。该项目的一个重要组成部分是使海上科学家与课堂学生和公众接触。因此，该项目纳入了几项具体战略，包括：（1）从海上发布网络/视频博客;（2）聘请一名自由摄像师，在前往东北大西洋的游轮上收集多媒体内容，这些内容将用于各种游轮后的交付成果;（3）制作？看海？播客，使公众可以看，听和触摸海洋，并通过介绍正在进行的海洋学研究和采访海洋学家来揭开海洋的一些秘密;以及（4）将研究活动与正在进行的K-12教师研讨会相结合，作为海洋活动、资源和教育计划的一部分，并通过与海格特小学科学/技术教师劳拉·邓巴的互动（海格特，新泽西州）。

Intellectual Merit: Despite the critical importance of viruses in shaping marine microbial ecosystems, very little is known about the molecular mechanisms mediating phytoplankton-virus interactions. As a consequence, we currently lack biomarkers to quantify active viral infection in the oceans, significantly hindering our understanding of its ecological and biogeochemical impacts. The coccolithophore Emiliania huxleyi (Prymnesiophyceae, Haptophyte) is a cosmopolitan unicellular photoautotroph whose calcite skeletons account for about a third of the total marine CaCO3 production. E. huxleyi forms massive annual spring blooms in the North Atlantic that are infected and terminated by lytic, giant double-stranded DNA containing coccolithoviruses. Findings that lytic viral infection of E. huxleyi recruits the hosts programmed cell death (PCD) machinery demonstrate that viruses employ a sophisticated, co-evolutionary ?arms race? in mediating host-virus interactions. The investigators recently demonstrated that viral glycosphingolipids (vGSLs), derived from unexpected cluster of sphingolipid biosynthetic genes, a pathway never before described in a viral genome, play a crucial functional role in facilitating infection of E. huxleyi. The observations of vGSLs in the North Atlantic and Norwegian fjords further suggest that they may be novel, diagnostic biomarkers for viral infection of coccolithophore populations. At the same time, the discovery of vGSLs and a distinct, protective 802 lipid argues that a host-virus, co evolutionary chemical arms race plays a pivotal role in regulating viral infection and in lubricating upper ocean biogeochemical fluxes of C and S.The focus of this project is to elucidate the molecular, ecological, and biogeochemical links between vGSLs (and other polar lipids) and the global cycles of carbon and sulfur. The team of investigators proposes a multi-pronged approach combing a suite of lab-based, mechanistic studies using several haptophyte-virus model systems along with observational studies and manipulative field-based experiments the Northeast Atlantic. Using these diagnostic markers, they will document active viral infection of natural coccolithophore populations and couple it with a suite of oceanographic measurements in order to quantify how viral infection (via vGSLs) influences cell fate, the dissolved organic carbon (DOC) pool, vertical export of particular organic (POC) and inorganic carbon (PIC; as calcium carbonate, CaCO3) (along with associated alkenone lipid biomarkers and genetic signatures of viruses and their hosts) and the upper ocean sulfur cycle (via the cycling of dimethylsulfide [DMS] and other biogenic sulfur compounds). Furthermore, given they are unique to viruses, they propose that vGSLs can be used to trace the flow of virally-derived carbon and provide quantitative insights into a ?viral shunt? that diverts fixed carbon from higher trophic levels and the deep sea. The overarching hypothesis for this study is that vGSLs are cornerstone molecules in the upper ocean, which facilitate viral infection on massive scales and thereby mechanistically ?lubricate? the biogeochemical fluxes of C and S in the ocean.Broader Impact: This research blends concepts in physiology, molecular biology, biochemistry, viriology and lipid chemistry, with oceanography and biogeochemistry, thereby providing an opportunity whereby researchers with different educational backgrounds can interact and develop. This project provides excellent hands-on training for development of postdocs, graduate students and undergraduate students. The research provides resources and opportunities for inter-institutional exchange Rutgers-WHOI-College of Charleston and builds both on established national and international collaborations and will foster new ones. The PIs will work with COSEE NOW and ?Networked Ocean World? to increase ocean literacy by integrating scientific research with K-12 educators and public audiences. An important component of this project is to bring scientists at sea in touch with classroom students and the general public. As such, the project incorporates several concrete strategies, including: (1) posting web/video blogs from sea; (2) incorporating a freelance videographer to collect multimedia content on a cruise to the Northeast Atlantic, which will be used in diverse post-cruise deliverables; (3) producing ?Ocean Gazing? podcasts so the general public can look at, listen to and touch the ocean and unpack some of its secrets by presenting ongoing oceanographic research and interviewing oceanographers; and (4) integrating the research activities with ongoing K-12 teacher workshops as part of the Marine Activities, Resources and Education program and through interactions with Laura Dunbar, a Science/Technology teacher at Sea Girt Elementary School (Sea Girt, NJ).