The Ecology of Prochlorococcus: Toward a Model System for Microbial Oceanography

原绿球藻的生态学：建立微生物海洋学模型系统

• 批准号: 0425602
• 负责人: Sallie Chisholm
• 金额: $ 120万
• 依托单位: Massachusetts Institute of Technology
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2004
• 资助国家: 美国
• 起止时间: 2004-09-01 至 2010-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0425602&HistoricalAwards=false
• 关键词: Ecology; Prochlorococcus; Toward; Model; System

The power of a model system for advancing our understanding of the natural world has been proven repeatedly in diverse sub-disciplines of science. This approach is equally valuable for the study of marine microbial ecology, either through the sustained study of a particular ecosystem, or through the study of a particular organism at all scales of organization from the genome to the ecosystem level. In this project the investigators will do the latter through a diverse set of laboratory and field studies designed to advance the understanding of Prochlorococcus, the numerically dominant phytoplankter in the world oceans. The objective is to understand what regulates the distribution and abundance of this important primary producer. Prochlorococcus has a number of features that make it a useful model organism for understanding the forces that shape marine microbial systems, and for generating hypotheses that will advance the field of Microbial Oceanography. It is the smallest and most abundant photosynthetic cell in the oceans, it can be isolated into culture, and it can be easily enumerated and studied in situ. Furthermore, it has the smallest genome of any known photosynthetic cell -- the minimal phototroph to date. Prochlorococcus is really a collection of "ecotypes", i.e., closely related but physiologically distinct populations that co-exist with different distributions along the light, temperature, nutrient, and predator (including viruses) gradients that shape their habitat. These distributions are determined by the relative fitness of the cells, i.e. the balance of growth rates and death rates along these gradients. The broad challenge is to understand the forces that have shaped this microdiversity over evolutionary time, and that guide the self-organization of these populations under different selective regimes. This is a multi-dimensional project designed to understand the "bottom up" (growth limitation by light, temperature, oxygen, and nutrients) and "top down" (mortality from viruses and grazing) influences on the population growth of different Prochlorococcus ecotypes through both laboratory and field studies. The project will involve high-throughput studies of the growth of ecotypes along gradients of environmental variables in the laboratory, as well as studies of the distribution of ecotypes along spatial and temporal gradients in the field (at the Hawaii and Bermuda Time Series Stations, along a longitudinal Atlantic transect, and in Oxygen Minimum Zones in the Arabian Sea and Peruvian Upwelling) using Q-PCR to assess their relative abundance. The investigators will also study the life cycle of viruses that infect Prochlorococcus and cross infect between ecotypes, and the growth and mortality rates of specific ecotypes in field samples due to grazing pressure. Another set of analyses will measure the full diversity of co-occurring Prochlorococcus in selected field samples, and work toward understanding at what level genetic diversity corresponds to ecologically meaningful diversity. Finally, the study will develop statistical methods for the characterization and analysis of Prochlorococcus ecotype "fitness spaces" established in the laboratory, and compare them with the distribution of ecotypes along environmental gradients in the field. This will allow a rigorously analysis of the degree to which different selective pressures shape the relative abundance of the different Prochlorococcus ecotypes in the oceans, and how they change over time and space. Broader Impacts. This project will support (in whole or in part) the research of 5 graduate students and post-docs, three of them women, as well as undergraduate researchers. Through a formal collaboration with the Museum of Science we will also develop exhibits that focus on marine microbiology. The investigators are also participating in MIT's Knowledge Update Program, which produces multi-media educational briefings designed for both professional and student audiences to provide a focused, quick immersion into emerging fields. Finally, the participants will be working with an anthropologist at MIT who is working on a book, tentatively entitled Mapping a Sea of Genes, that will offer an anthropological look at exploring the ocean in the age of genomics. The author has been interacting with the research group to get a documentary sense of work on ocean microbes and their genes. This book will transform the way scientists, policy makers and lay public understand the sea.

在科学的各种子学科中，反复证明了一种模型体系来促进我们对自然世界的理解的力量。 这种方法对于通过对特定生态系统的持续研究或通过从基因组到生态系统层面的所有组织的特定生物进行研究，对于海洋微生物生态学的研究同样有价值。 在这个项目中，研究人员将通过一套多样化的实验室和现场研究来进行后者，旨在促进对世界海洋中数值主导的浮游植物占主导地位的氯环球菌的理解。 目的是了解是什么调节了这一重要主要生产者的分布和丰度。 ProChorococcus具有许多特征，使其成为理解塑造海洋微生物系统的力的有用模型生物，并产生将推进微生物海洋学领域的假设。 它是海洋中最小，最丰富的光合细胞，可以分离成培养物，可以很容易地列举和研究。 此外，它具有任何已知的光合细胞的最小基因组 - 迄今为止最小的光养育。 占地氯环球确实是“生态型”的集合，即密切相关但生理上不同的种群，与沿光，温度，养分和捕食者和捕食者（包括病毒）梯度共存的人群，这些分布不同，这些梯度会影响其栖息地。 这些分布取决于细胞的相对适应性，即沿这些梯度的生长速率和死亡率平衡。 广泛的挑战是了解在进化时代塑造了这种微观多样性的力量，并指导在不同选择性制度下这些人群的自组织。这是一个多维项目，旨在了解“自下而上”（受光，温度，氧气和养分的生长限制）和“自上而下”（病毒和放牧的死亡率）对通过实验室和现场研究均对不同核酸菌群生态型的种群增长的影响。 该项目将涉及对实验室环境变量沿环境变量梯度增长的高通量研究，以及该领域中沿空间和时间梯度沿空间和时间梯度的分布的研究（在夏威夷和百慕大时代时期（在夏威夷和百慕大时间系列中丰富。 研究人员还将研究感染核球菌并在生态型之间交叉感染的病毒的生命周期，以及由于放牧压力而导致的田间样品中特定生态型的生长和死亡率。 另一组分析将衡量所选场样品中共氯环菌的全部多样性，并致力于了解哪种水平遗传多样性对应于生态意义上的多样性。 最后，该研究将开发用于在实验室中建立的核酸型生态型“适应性空间”的表征和分析的统计方法，并将它们与现场环境梯度沿环境梯度的分布进行比较。 这将允许对不同选择压力塑造海洋中不同甲氯环球菌的相对丰度的程度进行严格的分析，以及它们如何随时间和空间的变化。更广泛的影响。 该项目（全部或部分）将支持5名研究生和教育生的研究，其中3个女性以及本科研究人员。 通过与科学博物馆的正式合作，我们还将开发以海洋微生物学的展览。 调查人员还参加了MIT的知识更新计划，该计划为专业和学生观众设计了多媒体教育简报，以提供集中，快速沉浸在新兴领域的情况下。 最后，参与者将与麻省理工学院的人类学家合作，该书正在研究一本书，暂定题为“绘制基因之海”，该书将提供人类学的外观，以探索基因组学时代的海洋。 作者一直与研究小组进行互动，以获得有关海洋微生物及其基因的纪录片。 这本书将改变科学家，政策制定者和公众理解大海的方式。