Amino Acid Molecular-Level Stable Isotopic and Enantiomeric Ratios: A New Approach for Understanding Source and Transformation of Organic Nitrogen in the Sea.

氨基酸分子水平稳定同位素和对映体比率：了解海洋有机氮来源和转化的新方法。

• 批准号: 0623622
• 负责人: Matthew McCarthy
• 金额: $ 42.91万
• 依托单位: University of California-Santa Cruz
• 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: 2006-09-15 至 2011-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0623622&HistoricalAwards=false
• 关键词: Amino; Acid; Molecular; Level; Stable

ABSTRACTProposal # OCE-0623622Particulate and dissolved organic nitrogenous material (PON & DON) represent the major active pools of reduced organic N in the ocean. Sinking PON and advected DON from the surface into the ocean's interior represent the main pathways for export of new production, nitrogen flux and remineralization, as well as long-term organic nitrogen storage as DON in the deep sea. The chemical identity of organic nitrogen is key to understanding its sources, roles in ocean food webs, and the biogeochemical mechanisms that regulate its cycles. However, the large majority of PON in the deep ocean, and DON at all depths, cannot be identified at the molecular level. Accumulating evidence now indicates that this material is composed of largely unaltered biomolecules (amide N functions), and is likely dominated in most reservoirs by amino acids (AA). While hydrolyzable AA composition has long been a powerful tool for investigating diagenetic transformations, traditional AA measurements have intrinsic limitations for differentiating specific sources and transformations of ON in the ocean's water column.In this research, two PIs from University of California Santa Cruz will develop a new set of molecular-level tools based on the recognition of *15N and *13C AA stable isotopic patterns that potentially record both a metabolic signature of their synthetic origin, as well as diagnostic signatures of subsequent heterotrophic transformations. They hypothesize that, together with enantiomeric (D/L) ratios, *15N and *13C AA signatures can be used to determine both ultimate source and heterotrophic processing of organic N at a level of specificity and detail that has not previously been possible. To test these hypotheses, they will conduct a set of lab experiments using multiple prokaryotic and eukaryotic algae in a linked series of feeding experiments with bacterial, protist, and macrozooplankton transformations. Upon completion of this proposal, ocean scientists will be in an excellent position to extend these methods from the laboratory to field studies with confidence. Among its broader impacts, this proposal will have far-reaching implications for our basic understanding of how organic nitrogen cycling works in the ocean. This in turn would have direct and indirect impacts on our understanding of carbon cycling, as well as how other researchers parameterize regional and global biogeochemical models. Undergraduate, graduate and post-doctoral education will be furthered through active participation in laboratory and data synthesis activities. Two graduate students will be provided a unique educational background in molecular level isotopic tools and biogeochemistry. Undergraduate research will also be involved throughout the project.

摘要提案# OCE-0623622颗粒和溶解的有机含氮物质（PON 和 DON）代表海洋中有机氮减少的主要活性池。 PON 和从表面平流输送到海洋内部的 DON 代表了新产量、氮通量和再矿化的输出以及深海中 DON 长期有机氮储存的主要途径。有机氮的化学特性是了解其来源、在海洋食物网中的作用以及调节其循环的生物地球化学机制的关键。然而，深海中的绝大多数 PON 以及所有深度的 DON 都无法在分子水平上进行识别。现在越来越多的证据表明，这种材料主要由未改变的生物分子（酰胺 N 功能）组成，并且在大多数储层中可能以氨基酸 (AA) 为主。虽然可水解的 AA 成分长期以来一直是研究成岩转化的有力工具，但传统的 AA 测量对于区分海洋水柱中 ON 的特定来源和转化具有内在的局限性。在这项研究中，来自加州大学圣克鲁斯分校的两位 PI 将开发一种一套新的分子水平工具，基于 *15N 和 *13C AA 稳定同位素模式的识别，可能记录其合成来源的代谢特征，以及随后异养的诊断特征转变。他们假设，与对映体 (D/L) 比率一起，*15N 和 *13C AA 特征可用于确定有机氮的最终来源和异养加工，其特异性和细节水平以前是不可能的。 为了检验这些假设，他们将在一系列与细菌、原生生物和大型浮游动物转化相关的喂养实验中使用多种原核和真核藻类进行一系列实验室实验。 该提案完成后，海洋科学家将处于有利地位，可以充满信心地将这些方法从实验室扩展到现场研究。在其更广泛的影响中，该提案将对我们对海洋中有机氮循环如何运作的基本理解产生深远的影响。这反过来又会对我们对碳循环的理解以及其他研究人员如何参数化区域和全球生物地球化学模型产生直接和间接的影响。通过积极参与实验室和数据综合活动，本科生、研究生和博士后教育将得到进一步发展。两名研究生将获得分子水平同位素工具和生物地球化学方面独特的教育背景。本科生研究也将参与整个项目。