Collaborative Research: Are diatoms chemically or mechanically defended against protist grazers?

合作研究：硅藻是否通过化学或机械方式防御原生食草动物？

• 批准号: 0551436
• 负责人: Suzanne Strom
• 金额: $ 46.76万
• 依托单位: Western Washington University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2006
• 资助国家: 美国
• 起止时间: 2006-03-01 至 2010-02-28
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0551436&HistoricalAwards=false
• 关键词: Collaborative; Research; diatoms; chemically; mechanically; Collaborative; Research; diatoms; chemically; mechanically

In geologically recent times, diatoms have evolved to become one of the most successful phytoplankton taxa in the sea, responsible for an estimated 40% of marine primary production. The sustained blooms that diatoms often experience are one attribute leading to their high primary production. What allows so many diatom cells to escape the zooplankton grazing pressure that removes most other phytoplankton from the sea on a daily basis? Recently, both chemical and mechanical defenses have been hypothesized to deter grazers that might otherwise consume diatoms. Reactive polyunsaturated aldehydes (PUAs) derived from C20 fatty acids upon diatom wounding have been shown to inhibit cellular processes in numerous marine organisms. When adult copepods are fed a diet rich in PUA-producing diatoms they are unaffected. However, their reproductive potential can be impaired in a number of ways, including decreased egg production, reduced hatching success, and poor survival of larvae. This 'insidious' chemical defense thus appears to function by reducing grazing impacts of subsequent generations of copepods. The diatom frustule has also been hypothesized to reduce predation by mechanically defending the cell - acting as armor - against certain types of consumers. There is preliminary indications that microzooplankton, primarily protists, often graze substantially more diatom production than do crustacean zooplankton, and might provide selective pressure for the evolution of diatom defenses. This research will consist of a series of experiments to test diatom defenses against grazing and reproduction by several taxa of diatom-feeding protists, including heterotrophic dinoflagellates and large ciliates. The production of PUAs by diatoms under different growth conditions will be measured using recently developed GC-MS techniques. Protist grazing, digestion and growth rates will be compared when fed closely related strains of diatoms that produce different levels of PUAs. Fluorescent probes will be used to assess modes of cell damage in affected protist grazers. To test mechanical defenses, we will grow diatoms under different levels of silicic acid availability to generate different frustule thicknesses, and then assess grazing, digestion and growth rates of their protist grazers. This research will contribute to our understanding of the regulation of diatom (and hence total marine) primary production, as well as to fundamental ecological questions about the evolution of plant defense pathways in the marine plankton.Broader Impacts:This project will directly involve undergraduate students in research through three programs. At OSU, chemistry-oriented students from the Honor College will be recruited to participate in the organic chemistry aspects of this research. At SPMC, undergraduate participants in SPMC's summer REU program and ethnic minority students from the Minorities in Marine Science Undergraduate Program (MIMSUP) will participate in phyto- and microzooplankton experimental aspects of the project. Funds are included to support the research of one or more WWU graduate students. Scientific findings will be disseminated broadly though participation in national meetings and publication in peer-reviewed journals.

在地质上，硅藻已经发展成为海洋中最成功的浮游植物分类单元之一，估计占海洋初级生产的40％。硅藻经常经历的持续开花是导致其主要产量高的一个属性。是什么允许这么多的硅藻细胞逃脱浮游生物的放牧压力，该压力每天从海中消除大多数其他浮游植物？最近，已经假设化学和机械防御能力阻止可能消耗硅藻的放牧者。已证明，在硅藻损伤时衍生出源自C20脂肪酸的反应性多不饱和醛（PUA）已显示可抑制许多海洋生物的细胞过程。当成年co脚喂养富含pua的硅藻的饮食时，它们就不会受到影响。但是，它们的生殖潜力可能会以多种方式受损，包括卵产量减少，孵化成功降低和幼虫存活不良。因此，这种“阴险”的化学防御似乎是通过减少随后几代Copepods的放牧影响来起作用。还假设硅藻膜通过机械地捍卫电池 - 用作装甲的细胞来减少捕食。有初步的迹象表明，主要是原生生物的Microzooplankton通常比甲壳类动物浮游生物要大得多，并且可能为硅藻防御的演变提供选择性的压力。这项研究将包括一系列实验，以测试几个硅藻喂养生物的分类群（包括异养鞭毛藻和大纤毛）的分类单元的硅藻防御和繁殖。在不同的生长条件下，将使用最近开发的GC-MS技术来测量硅藻的PUA。当产生不同水平的PUA的硅藻菌株时，将比较生物放牧，消化和生长速率。荧光探针将用于评估受影响的捕食者的细胞损伤模式。为了测试机械防御，我们将在不同水平的硅酸可用性下种植硅藻，​​以产生不同的裂纹厚度，然后评估其植物放牧者的放牧，消化和生长速率。这项研究将有助于我们理解对硅藻的调节（以及总海洋生产）的调节，以及有关海洋浮游生物中植物防御途径进化的基本生态问题。Broader的影响：该项目将直接涉及通过三个方案的研究学生参与研究的本科生。在OSU，将招募以化学为导向的学生参加这项研究的有机化学方面。在SPMC，SPMC夏季REU计划的本科参与者和来自海洋科学本科课程（MIMSUP）的少数民族少数民族学生将参加该项目的Phyto-和Microzooplankton实验方面。包括资金来支持一名或多个WWU研究生的研究。通过参加同行评审期刊的国家会议和出版物的参与，科学发现将广泛传播。