Collaborative Research: Relating detrital peptide sequences to particulate organic matter diagenetic histories

生物、化学和物理过程改变了最近沉积的海洋沉积物。在这种通常被称为早期成岩作用的变化过程中，有机质的数量和组成发生了变化，从而影响了海洋碳循环的关键组成部分。在这项研究中，研究人员将使用分析技术来评估早期成岩过程中多肽的地球化学，并开发评估细菌所起作用的方法。这项研究很重要，因为多肽等有机分子会影响海洋中碳和氮的降解速度和去向，因此对于理解这些关键营养物质的地球化学循环具有广泛的相关性。该项目还将为本科生和研究生提供研究机会，并通过为来自未被充分代表的社区的女中学生提供暑期实习机会，鼓励下一代海洋科学家的多样性(项目COOL)。大多数成岩指数是基于氨基酸组成来评估有机质在早期成岩作用中的程度。总的可水解氨基酸组成以粗略的方式表示有机物的降解状态、生物有效性和来源。进一步发展氨基酸作为评估地球化学过程的工具，需要包括多肽链中包含的丰富信息，这些信息目前在水解过程中丢失。对碎屑多肽进行排序的一种有效方法是应用串联质谱学，然后进行从头测序。在这个项目中，研究人员将使用从头测序来评估早期成岩过程中的肽和蛋白质地球化学，并开发一种肽聚糖特异的定量方法，使其能够利用在不同细菌中发现的独特的肽聚糖多肽结构。根据该项目将采取的具体行动包括(1)对一组特征良好的档案样本进行从头测序，(2)进行一系列吸附实验，以评估不同碎屑多肽附着在矿物表面并受到保护不被降解的倾向，以及(3)开发一种测量多肽的定量方法。通过将碎屑多肽与样本集的其他已知数量进行比较，将评估有机质成岩作用与多肽来源、序列和保存之间的关系。

Biological, chemical, and physical processes alter recently deposited marine sediments. During this alteration, commonly referred to as early diagenesis, the quantity and composition of organic matter is changed which influences key components of the marine carbon cycle. In this study, researchers will use analytical techniques to evaluate the geochemistry of peptides during early diagenesis, and develop methods for assessing the role bacteria play. This research is important because organic molecules such as peptides influence degradation rates and the fate of carbon and nitrogen in the ocean, and therefore have broad relevance for understanding the geochemical cycling of these key nutrients. The project will also involve research opportunities for undergraduate and graduate students, as well as encourage diversity in the next generation of ocean scientists by providing summer internship opportunities for female middle school students from underrepresented communities (Project COOL).Most diagenetic indices for evaluating how "far along" organic matter is in its early diagenesis are based on amino acid compositions. Total hydrolyzable amino acid compositions indicate, in a coarse manner, organic matter degradation status, bioavailability, and source. Further development of amino acids as tools to assess geochemical processes requires including the wealth of information held within the peptide chains, information that is currently lost during hydrolysis. A powerful approach to sequencing detrital peptides is the application of tandem mass spectroscopy followed by de novo sequencing. In this project, researchers will use de novo sequencing to evaluate peptide and protein geochemistry during early diagenesis, and to develop a peptidoglycan-specific quantification method that allows utilization of the unique peptidoglycan peptide structures found in different bacteria. Specific actions to be taken under this project include (1) applying de novo sequencing to a set of well-characterized archive samples, (2) conducting a set of sorption experiments to evaluate the propensity for different detrital peptides to adhere to mineral surfaces and be protected from degradation, and (3) developing a quantitative method for measuring peptidoglycan peptides. By comparing detrital peptides to other known quantities of the sample set, relationships between organic matter diagenesis and peptide source, sequence, and preservation will be assessed.