Trojan Horses in the Marine Realm: Protist Parasite-host Dynamics in Coastal Waters

人们认识到寄生甲藻的生态重要性已经有一段时间了，特别是在疫情暴发期间，这些疫情导致宿主大量死亡，破坏水产养殖，并使具有商业价值的甲壳类变得令人不快。在国际全球海洋调查中发现的最主要的寄生甲藻类群被称为Malv II Syndiniales。在浮游环境中，Malv II Syndiniales组不仅对猎物种群施加自上而下的控制，而且基于它们明显的无处不在和丰富，它们很可能塑造海洋水柱中的营养池。对养殖样本的数据显示，这种超多样化的群体可以感染广泛的原生宿主，以及桡足类和鱼类幼虫。在宿主-寄生虫相互作用的特殊性和动态方面的知识差距导致难以估计对沿海生态系统的影响。在这个项目中，研究人员结合了显微镜、基因组学和化学的新方法，在一年的周期内跟踪沿海地点的宿主-寄生虫动态，然后建立模型来评估对微生物生态系统动态的影响。研究人员将让本科生和高中生参与实地和实验室研究活动。此外，还包括对研究生的支持，以及通过出版物和演讲更广泛地传播研究成果的计划。新月形目寄生虫是海洋环境中一种广泛存在的共生相互作用，尽管研究不足，但对这些寄生虫对原生生物种群的调节知之甚少。尽管它们在全球海洋中的分布是世界性的，在原生生物标记基因的分子数据库中也表现出丰富的数量，但人们对这些寄生虫的生态学知之甚少，几乎没有关于它们的基因组数据。在这个项目中，研究人员将高分辨率采样、水化学(包括营养物质)分析、分子标记基因分析、荧光原位杂交、单细胞基因组学和建模相结合，首次在沿海海洋生态系统的群落水平上对宿主-MALVII寄生虫的动态和生态进行了重点评估。研究人员将评估宿主和寄生虫多样性的时间动态，并将使用盐池、法尔茅斯、马萨诸塞州高分辨率采样和原位杂交显微镜检查原生生物群落感染水平和宿主-寄生虫特异性的时间变化。分子方法包括扩增标签高通量测序，利用新兴的第三代测序技术，牛津纳米孔的宠儿来阐明宿主-寄生虫的身份。研究人员还将应用单细胞基因组测序的进展来了解菌株特定的基因组内容，包括支持原生生物寄生的分子机制。将使用实验室实验来评估盐池中几个最常见的受感染宿主分类群对颗粒和溶解有机物池的贡献，这将提供第一组值来模拟新月形目寄生对有机和无机营养库的影响。这一奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

The ecological importance of parasitic dinoflagellates has been recognized for some time, particularly during epidemic outbreaks that cause mass mortality of their hosts, damage to aquaculture, and render commercially valuable Crustacea unpalatable. The dominate parasitic dinoflagellate group found in international global ocean surveys is referred to as MALV II Syndiniales. In the planktonic environment, the MALV II Syndiniales group not only exerts top-down controls on their prey populations, but based on their apparent ubiquity and abundance, they likely shape the pools of nutrients in marine water columns. Data on cultured samples reveals this hyper-diverse group can infect a wide range of protist hosts, as well as copepods, and fish larvae. Gaps in knowledge of the specificity and dynamics of the host-parasite interactions contribute to difficulties in estimating the impacts on the coastal ecosystems. In this project, researchers combine novel methods in microscopy, genomics, and chemistry to track host-parasite dynamics at a coastal site over an annual cycle followed by modeling to assess the impacts on microbial ecosystem dynamics. The researchers will engage undergraduate and high school students in field and laboratory research activities. In addition, support for a graduate student is included along with plans to disseminate the research results more broadly through publications and presentations.Syndiniales parasitism is a widespread, albeit under-studied symbiotic interaction in the marine environment and little is known about regulation of protist populations by these parasites. In spite of their cosmopolitan distribution in the global ocean and their apparent abundance in molecular datasets of protist marker genes, little is known about the ecology of these parasites and almost no genomic data exists for them. In this project, the researchers combine high-resolution sampling, water chemistry (including nutrients) analyses, molecular marker gene analyses, fluorescence in situ hybridization, single cell genomics, and modeling to produce the first focused assessment of host-MALVII parasite dynamics and ecology at the community level in a coastal marine ecosystem. The researchers will evaluate temporal dynamics of host and parasite diversity and will examine temporal variation in levels of infection of the protist community and host-parasite specificity using high-resolution sampling in Salt Pond, Falmouth, MA, and in situ hybridization microscopy. Molecular approaches include amplicon tag high throughput sequencing, leveraging the emerging third generation sequencing technology, Oxford Nanopore's MinION to elucidate host-parasite identities. The researchers will also apply advances in single-cell genome sequencing to inform on strain-specific genome content, including the molecular mechanisms underpinning protist parasitism. Contributions to pools of particulate and dissolved organic matter will be estimated for several of the most commonly infected host taxa in Salt Pond using laboratory experiments, providing the first set of values for modeling impacts of Syndiniales parasitism on pools of organic and inorganic nutrients.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.