Molecular Probes for Nutrient Stress in Phytoplankton: Emiliania Huxleyi as a Model

浮游植物营养胁迫的分子探针：以赫胥黎Emiliania huxleyi为模型。浮游植物的类型和生理状态影响海洋中的主要过程，如碳固定、钙化、硫气体排放和有毒水华形成，这样的例子不胜数。然而，我们了解单个浮游植物物种或单个细胞的生理状态的能力是有限的。目前，大多数生物野外测量（例如碳固定、碳氮比、Fv/Fm）整合了整个浮游植物群落。从长远来看，对单个“关键”浮游植物物种的生理生态学的理解将为生态系统过程提供更机械、更预测性的理解。赫胥黎藻是一种丰富的世界性浮游植物，由于其在方解石（球石）水柱和硫气体DMS中产生，在全球碳和硫的生物地球化学循环中具有重要意义。它既存在于贫营养环境中，也存在于浅海环境中，在某些地方，可以在卫星图像上看到大量的水华。迄今为止，我们对这种生物生态学的理解主要集中在这些开花现象上。浮游植物生态学领域的研究目标之一是开发不依赖于孵化的浮游植物营养状况探针。根据之前的工作，已经开发出一种针对细胞表面蛋白NRP1的抗体，这种抗体存在于氮胁迫下，但不存在于硝酸盐或氨充满的E. huxley。在本研究中，该抗体将用于开发一种野外方法来表征天然赫胥黎氏杆菌群体的生理状态。全细胞试验将被优化，其效率和灵敏度特征为检查细胞数量下降到那些存在于少营养环境。荧光显微镜和图像分析将用于量化表达NRP1的细胞数量和理想的相对表达水平。将开发一种针对完整细胞的抗体，用于计算样品中氮胁迫细胞的总数和百分比。先前从加利福尼亚海流和挪威海岸获得的一些样本将首先在现场测试氮应激细胞的存在。对特定浮游植物群的生理状态的论证将是新颖的。这项工作将包括培训一名研究生和一名或多名本科生应用免疫学探针解决海洋生态问题的新兴技术。

Palenik 9818543Molecular Probes for Nutrient Stress in Phytoplankton: Emiliania huxleyi as a model.Numerous examples exist where both the type and physiological status of the phytoplankton influence major processes in the oceans such as carbon fixation, calcification, sulfur gas emission, and toxic bloom formation. Our ability to understand the physiological status in the field of individual phytoplankton species or individual cells is limited, however. Most biological field measurements (carbon fixation, C:N ratio, Fv/Fm, for example) currently integrate over the whole phytoplankton community. In the long term, an understanding of the physiological ecology of individual "keystone" phytoplankton species will provide a more mechanistic, predictive understanding of ecosystem processes.Emiliania huxleyi is an abundant, cosmopolitan phytoplankton species which is important in the global biogeochemical cycles of carbon and sulfur because of its production in the water column of calcite (coccoliths) and the sulfur gas DMS. It is present in both oligotrophic and neritic environments and in some locations is known to form massive blooms visible in satellite images. To date our understanding of the ecology of this organism has focused on these bloom phenomena.One of the research goals of the field of phytoplankton ecology is the development of incubation-independent probes of phytoplankton nutrient status. From previous work an antibody to a cell surface protein, NRP1, that is present in nitrogen-stressed, but not nitrate--replete or ammonia-replete E. huxley has been developed. In this study the antibody will be used to develop a field method for characterizing the physiological state of natural E. huxleyi populations. A whole cell assay will be optimized and its efficiency and sensitivity characterized for examining cell numbers down to those present in oligotrophic environments. Fluorescence microscopy and image analysis will be used to quantify the number of cells expressing NRP1 and ideally the relative level of expression.An antibody to intact whole cells will be developed to count the total and percent nitrogen-stressed cells in samples. A few previously obtained samples from the California current and the coast of Norway will be tested initially for the presence of nitrogen-stressed cells in the field. The demonstration of the physiological state of a specific phytoplankton group would be novel. This work will involve the training of one graduate student and one or more undergraduates in emerging techniques for applying immunological probes to marine ecological questions.