Collaborative Research: Tracking the interacting roles of the environment, host genotype, and a novel Rickettsiales in coral disease susceptibility

鹿角珊瑚历来是佛罗里达和加勒比地区最丰富的造礁珊瑚之一，现在被列为极度濒危，主要是因为以前和反复发生的疾病事件。了解这种珊瑚的疾病易感性的整体机制是从事保护和恢复的从业者的首要关注。研究人员最近发现了一组寄生细菌，它们在A.当珊瑚礁暴露在营养物污染的沃茨时，会降低珊瑚的生长和健康。确定珊瑚宿主，这种寄生微生物和环境之间的相互作用如何与疾病易感性联系起来，为未来的恢复工作提供了关键的见解和更大的成功。然而，动物微生物组的复杂性和疾病的背景性质使得很难确定许多疾病爆发的具体原因。在这个项目中，研究人员进行实验，探索不同遗传菌株的珊瑚和这些细菌在各种营养情况下的相互作用，以更好地了解这种细菌如何影响鹿角珊瑚对疾病的易感性。该项目还描述了这种细菌珊瑚寄生虫的基因组学，宿主范围以及局部和全球分布，以确定其进化历史和生理学如何驱动这种重要珊瑚物种的疾病易感性。该项目培养了两名博士后，一名技术人员和七名学生（一名研究生，六名本科生），这些学生的综合科学涵盖海洋科学，生理学，遗传学，微生物学，组学和统计建模。佛罗里达的一个以研究为基础的课后项目扩大到包括微生物学，并创建了一个名为微生物战士的新项目模块，重点关注科学领域的女性。调查人员制作纪录片风格的电影和宣传材料，通过在莫特海洋实验室和俄勒冈州科学与工业博物馆的演讲，向当地和国家社区广泛宣传项目科学和保护工作。该项目由海洋科学部的生物海洋学项目和综合有机体系统部的共生、防御和自我识别项目共同资助。研究人员最近在珊瑚中发现了一种海洋立克次氏体细菌，这种细菌可以在氮和磷含量升高的情况下刺激生长。基于基因组重建和细菌地理学，这种细菌被归类为一个新的细菌属，Aquarickettsia，并表明它广泛与世界各地的石珊瑚。重要的是，使用一个模型系统，濒危的鹿角珊瑚，研究小组还表明，这种细菌在体内的生长与宿主生长减少和疾病易感性增加有关。该项目旨在更全面地评估这些诱导感染对珊瑚生理学和宿主细菌共生的机制和影响。研究人员对不同立克次体丰度的不同珊瑚基因型进行营养剂量实验。使用一系列组学和显微镜技术，该团队量化了对全生物表型的影响。研究人员还比较了这些细菌在不同Acroporid宿主和其他珊瑚属中的基因组，以评估细菌进化历史的各个方面，并确定其增殖，毒性和宿主特异性的可能机制。这个跨学科的项目机械地将营养物质与宿主、藻类共生体、和细菌寄生虫生理学，并通过探索宿主和寄生虫的基因型和生长动力学与环境背景相结合如何改变全生物表型来解释为什么这些反应存在自然变异。该奖项反映了NSF的法定使命，并被认为值得通过使用基金会的知识产权进行评估来支持。优点和更广泛的影响审查标准。

Historically one of the most abundant reef-building corals in Florida and the wider Caribbean, the staghorn coral, Acropora cervicornis, is now listed as critically endangered primarily because of previous and reoccurring disease events. Understanding the holistic mechanisms of disease susceptibility in this coral is a top concern of practitioners engaged in conservation and restoration. The investigators recently discovered a group of parasitic bacteria common within the microbial community of A. cervicornis that can reduce the growth and health of corals when reefs are exposed to nutrient polluted waters. Determining how interactions among the coral host, this parasitic microbe, and the environment are linked to disease susceptibility provides critical insight and greater success of future restoration efforts. Yet the complexity of animal microbiomes and the contextual nature of disease make it difficult to identify the specific cause of many disease outbreaks. In this project, the investigators conduct experiments to explore the interactions among different genetic strains of coral and these bacteria in various nutrient scenarios to better understand how this bacterium affects the susceptibility of staghorn coral to diseases. This project also characterizes the genomics, host range, and local and global distribution of this bacterial coral parasite to determine how its evolutionary history and physiology drive disease susceptibility in this important coral species. The project trains two postdocs, one technician, and seven students (one graduate, six undergraduates) in integrative sciences that span marine science, physiology, genetics, microbiology, omics, and statistical modeling. A research-based after school program in Florida is expanded to include microbiology and create a new program module called Microbial warriors, with a focus on women in science. The investigators produce documentary style films and outreach materials to broadly communicate the project science and conservation efforts to local and national communities via presentations at Mote Marine Lab and the Oregon Museum of Science and Industry. This project is co-funded by the Biological Oceanography Program in the Division of Ocean Sciences and the Symbiosis, Defense, and Self-recognition Program in the Division of Integrative Organismal Systems.The investigators recently identified a marine Rickettsiales bacterium that, in corals, can be stimulated to grow in the presence of elevated nitrogen and phosphorous species. Based on genomic reconstruction and phylogeography, this bacteria is classified as a novel bacterial genus, Candidatus Aquarickettsia, and showed that it is broadly associated with scleractinian corals worldwide. Importantly, using a model system, the endangered Acropora cervicornis coral, the team has also shown that the growth of this bacterium in vivo is associated with reduced host growth and increased disease susceptibility. This project aims to more completely evaluate the mechanisms behind and impacts of these inducible infections on coral physiology and host-bacterial symbiosis. The investigators conduct nutrient dosing experiments on different coral genotypes with various Rickettsiales abundances. Using a range of omics and microscopy techniques, the team quantifies the resulting effects on holobiont phenotypes. The investigators are also comparing the genomes of these bacteria in the different Acroporid hosts and other coral genera to evaluate facets of the bacterium's evolutionary history, as well as to identify possible mechanisms of its proliferation, virulence, and host specificity. This interdisciplinary project mechanistically links nutrients to temporal changes in host, algal symbiont, and bacterial parasite physiology and also explain why there is natural variation in these responses by exploring how host and parasite genotypes and growth dynamics combined with environmental contextuality alter holobiont phenotypes.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.