Molecular and isotopic composition of novel biomarkers in diatom frustules as indicators of past ocean conditions

该项目由华盛顿大学的研究人员与多位同事合作，将继续研究在硅藻树桩的有机基质中发现的有机分子或有机化合物类别是否为生物在表层海洋中生长的海洋条件的有用生物标志物。这些生物标志物很有用，因为硅藻占全球初级生产力的很大一部分，而且分布在全球，确保了它们的广泛适用性。球茎主要由二氧化硅组成，但在生物矿化过程中，有机化合物被包裹在硅质基质中。这种有机模板在古海洋学和相关研究中大多未被开发，但最近的工作表明，这些化合物是潜在的有用生物标志物。此外，有机分子中碳和氮的同位素特征可能会提供额外的信息和对生长过程中海洋条件的洞察。因此，本项目将调查硅藻树冠中有机化合物的组成，并利用分子同位素分析来充分捕捉硅藻树冠作为生态系统、生物地球化学循环和气候变化的记录器的潜力。该项目将主要涉及受控的实验室培养研究，但也将检查田间种群和表层沉积物样本，以检查影响小球茎有机模板的因素，特别是从这些小球茎中提取的类真菌孢子素氨基酸、长链多胺和甲壳素的分子和同位素组成。该项目还将检查物种组成是否会影响同位素特征。这些结果可以提供合适的生物标志物，反映不同的重要海洋条件，如过去的营养物质利用和环境胁迫(紫外线和营养物质)。该项目将提供审查海洋气候反馈的新方法，这将有助于澄清海洋对重大体制变化的反应。该项目将支持一名博士后研究员和一名研究生，并将继续与俄罗斯科学家进行国际合作。调查人员还将与华盛顿大学海洋科学教育卓越中心(COSEE)互动并参与其中，并为K-12学生开展外联活动。

This project by investigators from the University of Washington, and in collaboration with various colleagues, will continue to examine whether the organic molecules or classes of organic compounds found in the organic matrix of diatom frustules are useful biomarkers for the oceanographic conditions under which the organisms grew in the surface ocean. These biomarkers are useful as diatoms are responsible for a substantial fraction of global primary productivity and are globally distributed, ensuring their widespread applicability. Frustules are composed primarily of silica, but there are organic compounds entrapped in the siliceous matrix during biomineralization. This organic template is mostly unexploited in paleoceanographic and related studies, but recent work has suggested that these compounds are potential useful biomarkers. Additionally, it is possible that the isotopic signature of carbon and nitrogen in the organic molecules may provide additional information and insight into ocean conditions during growth. Therefore, this project will investigate the organic compound composition and employ molecular isotope analyses of organic compounds in diatom frustules to fully capture the potential of diatom frustules as recorders of the changes in ecosystems, biogeochemical cycles and climate. The project will involve mainly controlled laboratory culture studies, but will also examine field populations and surface sediment samples, to examine the factors that influence the organic template of frustules, and specifically the molecular and isotopic composition of mycosporine-like amino acids, long chain polyamines and chitin extracted from these frustules. The project will also examine whether species composition influences the isotopic signature. The results could provide suitable biomarkers reflective of different important oceanographic conditions, such as past nutrient utilization, and environmental stress (UV and nutrient). The project will provide new methods to examine ocean-climate feedbacks that will help clarify the response of oceans to major regime shifts. The project will support a post-doctoral investigator and a graduate student, and will involve continued international collaboration with Russia scientists. The investigators will also interact and be involved with the University of Washington's Center for Ocean Sciences Education Excellence (COSEE) and work on outreach activities for K-12 students.