Viral discovery and unlocking the role of viruses in taxon-specific microbial mortality

海洋中90%以上的生物物质按重量计算是微小的，这些微生物产生了地球上大约一半的氧气。在这个微生物环境中，每毫升有100到1亿个病毒，这是海洋中数量最多的“生命”。作为主要病原体，病毒只能通过感染细胞生物来繁殖；据估计，它们每天杀死海洋中约20%的生命。因此，病毒是导致死亡、生物地球化学循环和构建海洋生态系统的主要因素。尽管它们很重要，但我们对水生病毒及其对特定生物死亡的影响仍然知之甚少。近30年来，我的实验室在研究水生病毒及其生态系统影响方面一直处于领先地位。拟议的研究建立在这一基础上，并侧重于病毒发现和量化病毒在死亡率中的作用，这两个领域的新知识有可能产生重大影响。仍然有许多病毒有待发现，还有许多病毒未知或特征不佳的生物体。巨型病毒(GV)是一组具有高影响力发现潜力的病毒。这些病毒世界的利维坦拥有所有病毒中最大的基因组，并超过了一些细菌的大小和复杂性，弥合了细胞和病毒之间的鸿沟。已知这些病毒只感染原生动物，包括主要的浮游植物和浮游动物。然而，尽管测序数据显示它们广泛而丰富，但只有几个GV被分离出来感染浮游生物。分离出更多的GV可能有助于阐明它们的起源，并有助于阐明它们在自然界中的生物学和功能。另一个发现病毒的成熟领域是尚不存在已知病毒的有机体群体。通常，许多不同类型的病毒感染一个生物体；然而，在近200个已知的细菌门中，病毒只有39个已知。因此，很有可能发现具有不同生物学特性和未知蛋白质编码的新病毒谱系。病毒发现的最后一个领域是与桡足类、甲壳类浮游动物有关的病毒，这些病毒是鱼类的食物来源，但也可能是鱼类的病原体和潜在的疾病媒介。识别桡足类病毒将使我们能够在宿主种群中跟踪它们，这是确定它们与疾病关系的第一步。另一个重点领域是量化病毒对微生物死亡率的影响。病毒每天杀死大约20%的微生物，但通常是非常特定于宿主的，因此它们的影响将是选择性的。由于不同的微生物具有不同的生态系统功能，其影响可能是广泛的。新开发的方法将被用来观察特定微生物类群的死亡率。这将使我们能够检验这样一个假设，即生长最快的微生物受到最大的裂解，这对种群动态具有重要意义。

More than 90% of the living material in the ocean, by weight, is microscopic, and these microbes produce about half the planet's oxygen. Within this microbial milieu are 1 to 100 million viruses /mL, the most numerous "life" in the sea. As obligate pathogens, viruses can only reproduce by infecting cellular organisms; they are estimated to kill ~20 % of life in the ocean daily. Thus, viruses are major players in mortality, biogeochemical cycling and structuring marine ecosystems. Despite their importance, we still know relatively little about aquatic viruses and their impact on the mortality of specific organisms. For ~30 years, my laboratory has been a leader in the study of aquatic viruses and their ecosystem effects. The proposed research builds on this foundation, and focuses on virus discovery and quantifying the role of viruses in mortality, two areas where new knowledge has the potential for a large impact. There are still many viruses to be discovered, and many organisms for which viruses are unknown or poorly characterized. Giant Viruses (GVs) are a group of viruses where the potential for making high-impact discoveries is high. These leviathans of the viral world have the largest genomes of any viruses and surpass the size and complexity of those of some bacteria, bridging the gap between cells and viruses. These viruses are only known to infect protists, which include major groups of phytoplankton and zooplankton. Yet, only a few GVs have been isolated that infect plankton, even though sequencing data indicates they are widespread and abundant. Isolating more GVs may shed light on their origin and help elucidate their biology and function in nature. Another area that is ripe for viral discovery are groups of organisms for which no known viruses exist. Typically, many different types of viruses infect a single organism; yet, of almost 200 recognized bacterial phyla, viruses are only known for 39 of them. Hence, there is a high probability of discovering new viral lineages that have different biological properties and code for unknown proteins. The final area of viral discovery is viruses associated with copepods, crustacean zooplankton that are a food source for fish, but which can also be fish pathogens and potential vectors for disease. Identifying copepod viruses will allow us to track them in host populations, a first step in determining their relationship to disease. The other area of focus is on quantifying the impact of viruses on microbial mortality. Viruses kill about 20% of microbes each day, but are typically very host specific, so their impact will be selective. As different microbes have different ecosystem functions the effects may be broad. Newly developed methods will be used to look at the mortality of specific microbial taxa. This will allow us to test the hypothesis that the fastest growing microbes are subject to the greatest lysis, which has important implications for population dynamics.