The Role of Metacaspases in Mediating Cell Fate During Viral Infection of Unicelluar, Marine Phytoplankton

浮游植物是随洋流漂移的微小光自养生物，占地球生物量的1%，但它们占全球每年碳基初级生产力的近50%。维持如此高的产量与生物量比的稳定状态意味着，平均而言，这些生物每周都会生长、死亡和被替换。生物海洋学家用来解释浮游植物高裂解率的主要机制是病毒感染。然而，调节感染的分子机制实际上被忽视了，尽管它们具有重要的生态系统后果，例如将初级生产力与微生物食物网耦合以及短路向深海输出碳。本项目将研究metacaspase，一种假定的程序性细胞死亡（PCD）蛋白酶，是否通过在病毒感染时执行PCD来调节海洋浮游植物的命运。拟议的研究将具体阐明metacaspase表达和活性的调节是否控制对病毒感染的易感性或耐受性。通过整合生物化学、分子生物学和细胞通讯的概念，研究结果将从生物、生态和进化的角度为浮游植物PCD提供前所未有的见解。实验将利用一个由球石藻、赫胥黎Emiliania huxleyi及其特异性球石病毒（EhV）组成的藻病毒模型系统。实验将采用多种生理学、生物化学和分子生物学技术，包括免疫沉淀、遗传转化、聚合酶链反应、Western blot分析、酶活性测定、显微镜和流式细胞术。该项目将为研究生和本科生的发展提供优秀的实践培训，扩大女性的参与，并为不同水平的研究人员提供一个互动和发展的平台。它将以现有的国家和国际合作为基础，并促进新的合作。研究活动将与中大西洋海洋科学教育卓越中心（MA-COSEE）对接，通过参与K-12教师研讨会和新泽西州自由科学中心的推广项目，向城市，主要是少数民族，儿童和家庭介绍海洋科学。具体目标是激发人们对海洋微生物的巨大多样性和对海洋功能的大规模重要性的认识。

Phytoplankton, microscopic photoautotrophs that drift with the currents, account for 1% of the Earth's biomass, yet they are responsible for nearly 50% of global annual carbon-based primary productivity. Steady-state maintenance of such a high production to biomass ratio implies that, on average, these organisms grow, die, and are replaced weekly. The primary mechanism used by biological oceanographers to explain the high lysis rates of phytoplankton has been infection by viruses. However, the molecular mechanisms regulating infection have been virtually ignored, even though they have important ecosystem consequences, such as coupling primary productivity to microbial foodwebs and short-circuiting carbon export to the deep ocean. This project will investigate whether metacaspases, putative programmed cell death (PCD) proteases, mediate the fate of marine phytoplankton by executing PCD upon viral infection. Proposed research will specifically elucidate whether the regulation of metacaspase expression and activity controls susceptibility or tolerance to viral infection. By integrating concepts in biochemistry, molecular biology, and cell communication, results will provide unprecedented insight into phytoplankton PCD from organismal, ecological, and evolutionary contexts. Experiments will utilize an algal-virus model system, consisting of the coccolithophore, Emiliania huxleyi, and its specific Coccolithoviruses (EhV). Experiments will employ a variety of physiology, biochemistry, and molecular biology techniques including immunoprecipitation, genetic transformation, polymerase chain reaction, Western blot analysis, enzyme activity assays, microscopy, and flow cytometry. This project will provide excellent hands-on training for development of graduate and undergraduate students, broaden the participation of women, and provide a platform for researchers with different levels of training to interact and develop. It will build both on established national and international collaborations and foster new ones. Research activities will interface with the Mid-Atlantic Center for Ocean Science Education Excellence (MA-COSEE), by participating in K-12 teacher workshops and in outreach programs at New Jersey's Liberty Science Center that introduce urban, largely minority, children and families to marine science. Specific goals are to stimulate awareness of the immense diversity and large-scale importance of marine microbes to ocean function.