Collaborative Research: Using Transcriptomics to Understand Mechanisms of Stress Response and Toxin Production in Pathogenic and Toxigenic Microbes in Tropical Marine Waters

在这个项目中，来自夏威夷大学马诺亚分校、斯坦福大学和罗格斯大学的一个跨学科研究小组将研究夏威夷沿海水域的甘比铁饼、金黄色葡萄球菌和肠球菌的转录组——这些产生毒素的物种对人类的健康构成重大危害。他们的目标是阐明冈比锡产生毒素和细菌病原体金黄色葡萄球菌和粪便指示物肠球菌在阳光下失活的相关机制。由于生物体的转录组反映了在任何给定时间活跃表达的基因，本研究通过阐明目标生物体中信使RNA的表达水平，应该为毒素产生、应激反应和/或随后的细菌失活机制提供有价值的见解。该研究计划将围绕四个工作假设进行组织：H1：冈比亚铁饼产生雪卡毒素反映了受温度、光照和生长阶段影响的培养生理状况。H2：毒素（+）和毒素（-）培养物的高通量转录组分析将允许鉴定参与雪卡毒素产生的基因，并了解有利于该功能的光和营养条件。H3：粪肠球菌在海水中暴露于阳光下易受间接光失活，而金黄色葡萄球菌则不然。这可能是由于细胞内的类胡萝卜素色素的存在，它能够淬灭活性氧。H4：粪肠球菌和金黄色葡萄球菌通过上调编码蛋白质的基因来应对清澈海水中的光胁迫，这些基因可以修复细胞损伤并减轻氧化应激；这种“压力体”会随着暴露于光应力的增加而改变，显示出不再可能修复的压力。更广泛的影响：本研究将收集的信息预计将大大有助于推动娱乐用水和海产品消费方面的风险管理领域，超越对经验相关性的依赖，并制定基于对这些生物对人类健康构成威胁的机制理解的政策。

In this project an interdisciplinary research team from the University of Hawaii at Manoa, Stanford University, and Rutgers University will study the transcriptomes of Gambierdiscus, Staphylococcus aureus, and Enterococcus in Hawaiian coastal waters - toxin-producing species that pose significant health hazards to humans. Their goal is to elucidate the mechanisms associated with toxin production by Gambierdiscus and inactivation by sunlight of the bacterial pathogen, S. aureus, and the fecal indicator, Enterococcus. Because the transcriptome of an organism reflects the genes that are actively being expressed at any given time, this study, by elucidating levels of messenger RNA expression in the target organisms, should provide valuable insights into the mechanisms responsible for toxin production, responses to stress and/or subsequent bacterial inactivation. The research program will be organized around four working hypotheses: H1: Production of ciguatoxin by Gambierdiscus reflects the physiological condition of the culture as influenced by temperature, irradiance, and growth phase. H2: High throughput transcriptome analysis from toxin (+) and toxin (-) cultures will allow the identification of genes involved in ciguatoxin production and understanding of the light and nutrient conditions that favor this function. H3: Whereas E. faecalis is susceptible to indirect photoinactivation under exposure to sunlight in seawater, S. aureus is not. This is likely due to the presence of carotenoid pigments within the cells, which are able to quench reactive oxygen species. H4: E. faecalis and S. aureus respond to photo-stress in clear seawater by up-regulating genes that encode for proteins to repair cellular damage and mitigate oxidative stress; this "stressome" will change with increasing exposure to photostress, revealing the stress at which repair is no longer possible. Broader Impacts: The information that will be gathered in this study is expected to contribute significantly to advancing the field of risk management with respect to recreational water use and seafood consumption beyond reliance on empirical correlations and towards policies that are based on a mechanistic understanding of the threats these organisms pose to human health.