Unveiling the contributions and regulation of picoeukaryotic phytoplankton in oceanic environments.

揭示海洋环境中超微核浮游植物的贡献和调节。

• 批准号: 0836721
• 负责人: Alexandra Worden
• 金额: $ 20.4万
• 依托单位: Monterey Bay Aquarium Research Institute
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2008
• 资助国家: 美国
• 起止时间: 2008-05-15 至 2010-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0836721&HistoricalAwards=false
• 关键词: Unveiling; contributions; regulation; picoeukaryotic; phytoplankton

The growth rates and fate of primary producers in the oceans are key factors regulating carbon flux in the biosphere. While resource limitation is known to play a major regulatory role, the specific factors controlling growth and mortality of picophytoplankton (2 microm diameter) are poorly understood. In particular, due to the small size and low sinking quotient of these dominant primary producers, determinants of their fate and transport in the water column are critical to the development of predictive models of carbon flux and its likely perturbation due to climate change. Picophytoplankton is composed of cyanobacteria, (Prochlorococcus and Synechococcus) and small eukaryotes. While the picocyanobacteria have received much attention, little is known about the distribution and dynamics of picophytoeukaryotes, particularly in oceanic settings. The few comparative measurements made to date indicate that the productivity of picophytoeukaryotes can rival that of picocyanobacteria. Hence, knowledge regarding the role of picophytoeukaryotes in open ocean environments is urgently needed. However, this knowledge is only valuable when put in the context of the total picophytoplankton community and, therefore, quantification of picocyanobacteria must be also be included. The overall goal is to develop a method for determining underlying physiological controls of picophytoeukaryotes. A targeted approach will be used, combining flow sorting, cDNA libraries and Expressed Sequence Tags (EST), allowing real-time expressional responses to be identified. This knowledge will highlight key physiological constraints and information on molecular underpinnings of picoeukaryotic population dynamics as well as aiding future efforts to isolate open-ocean picoeukaryotes. This is an important additional benefit from the work since environmental clone library data has demonstrated that such picoeukaryotes are poorly represented in culture collections. Long-term, the environmental genomic approach developed will also provide a high throughput mechanism for profiling expressional responses (mRNA) in the field. In the proposed work, expressional responses will be evaluated in two ocean basins, the equatorial Atlantic and the South Pacific. Broader Impacts. The experimental functional genomics approach taken to elucidate real-time responses to environmental forcing factors is applicable to all eukaryotes, and of value to other microbial ecologists seeking to identify molecular underpinnings of in situ responses. Moreover, sequences derived from uncultured picoeukaryotes, in combination with advances in molecular phylogeny, have led to a dramatic reconsideration of eukaryotic evolution; the sequences generated herein should aid refinement of evolutionary studies and the "Tree of Life". The project will provide training for students at several educational levels, including at-risk minority high school students, undergraduates and two Ph.D. candidates. Information from the project will be incorporated into graduate and undergraduate level courses on Marine Microbial Ecology (taught by the PI). Project results will be available via two internet based formats, one tailored to the general public and one for the scientific community.

海洋中初级生产者的增长率和命运是调节生物圈中碳通量的关键因素。虽然资源限制是众所周知的，发挥主要的调节作用，具体因素控制picophytoplankton（2 microm直径）的增长和死亡率知之甚少。特别是，由于这些占主导地位的初级生产者规模小，下沉系数低，其命运和在水柱中的运输的决定因素是至关重要的碳通量及其可能的扰动，由于气候变化的预测模型的发展。浮游藻类由蓝藻（原绿球藻和聚球藻）和小型真核生物组成。虽然微微蓝细菌受到了广泛的关注，但对微微植物真核生物的分布和动态知之甚少，特别是在海洋环境中。到目前为止的几个比较测量表明，picophytoeukaryotes的生产力可以媲美picocyanobacteria。因此，迫切需要了解微微植物真核生物在开放海洋环境中的作用。 然而，这方面的知识是有价值的，只有在总picophytoplankton社区的背景下，因此，定量的picocyanobacteria也必须包括在内。总的目标是开发一种方法来确定潜在的生理控制picophytoeukaryotes。将使用靶向方法，结合流式分选、cDNA文库和表达序列标签（EST），允许识别实时表达响应。这方面的知识将突出关键的生理限制和信息的picoeukaryotes人口动态的分子基础，以及协助未来的努力，以隔离开放的海洋picoeukaryotes。这是这项工作的一个重要的额外好处，因为环境克隆库数据已经证明，这种微真核生物在培养物中的代表性很差。从长远来看，开发的环境基因组学方法也将提供一个高通量的机制，在该领域的分析表达反应（mRNA）。在拟议的工作中，表达的反应将在两个海洋盆地，赤道大西洋和南太平洋进行评估。更广泛的影响。实验功能基因组学的方法来阐明实时响应环境胁迫因素是适用于所有的真核生物，和其他微生物生态学家寻求确定原位反应的分子基础的价值。此外，来自未培养的picoeukaryotes的序列，结合分子生物学的进展，导致了显着的真核生物进化的重新思考;本文产生的序列应该有助于进化研究和“生命之树”的完善。该项目将为不同教育层次的学生提供培训，包括处境危险的少数民族高中生、本科生和两名博士生。候选人该项目的信息将被纳入研究生和本科生的海洋微生物生态学课程（由PI教授）。项目结果将通过两种基于互联网的格式提供，一种是针对公众的，另一种是针对科学界的。