Collaborative Research: A Molecular Isotope Perspective on the Processes of Organic Matter Preservation in Fossils

合作研究：从分子同位素角度研究化石中有机物的保存过程

• 批准号: 9417836
• 负责人: Stephen Macko
• 金额: $ 14.02万
• 依托单位: University of Virginia Main Campus
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 1995
• 资助国家: 美国
• 起止时间: 1995-02-01 至 1998-09-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9417836&HistoricalAwards=false
• 关键词: Collaborative; Research; Molecular; Isotope; Perspective

9417836 Macko Interpretations of the stable isotope record of residual organic matter in fossils requires a fundamental appreciation of the formation and transformation of the elemental pools of carbon and nitrogen during biosynthesis, diagenesis and preservation. A series of experiments are proposed to elucidate the effects of biosynthesis and diagenesis on the molecular and stable isotope composition of organic matter in biogenic minerals and sediments. Growth studies involving two species of planktonic foraminifera (Orbulina universa and Globigerina bulloides) will be conducted in collaboration with Dr. Howard Spero to compare the stable carbon and nitrogen isotope compositions of amino acid constituents of the shell protein to those of the diet. In addition to potentially identifying essential amino acids, the magnitude of isotope fractionations associated with trophic interactions will be assessed. A realistic assessment of biogenic signals from fossils requires an appraisal of the limits of isotope fractionation that can occur during diagenesis and the development of unambiguous criteria for evaluating the possible exchange of components with the preserving matrix. Simulation experiments are planned to evaluate the effects of diagenesis on the stable isotope composition of organic matter in fossils and sediments. Specifically, attempts will be made to assess the magnitudes of stable carbon and nitrogen isotope fractionations resulting from hydrolysis and humification. With respect to preservation, a major concern continues to be the ability to distinguish indigenous organic compounds from exogenous overprints. The further development of gas chromatography/combustion/isotope ratio mass spectrometry (GC/C/IRMS) for stable nitrogen isotope analysis of amino acid enantiomers in fossils will provide an independent method for verifying the stable carbon isotope analysis of amino acid enantiomers, the development of GC/C/IRMS for stable nitrogen isotope analysis is dependent upon e stablishing isotopically reproducible combustion techniques capable of oxidation and reduction of halogenated derivatives of amino acids. An important test of this method involves molecular stable carbon and nitrogen isotope analysis of D- and L- enantiomers of individual amino acids in Cretaceous age samples, which will include dinosaur eggs and associated embryonic skeletal components. These rare samples are being provided from sites in North America and China by Dr. Dale Russell and Dr. Jack Horner. If the isotopic signals verify indigeneity, it may be possible to use molecular stable isotopes to establish the identities and trophic levels of the adults that produced the eggs. This study will also provide, to the best of our knowledge, the first direct comparison of the distribution and stable isotope composition of amino acid constituents of shell and bone from the same fossil organisms. An additional sample set of Cretaceous age dinosaurs from the western Sahara is also being provided by Dale Russell for a detailed investigation of organic matter preservation and paleoecology.

9417836化石中残留有机物的稳定同位素记录的Macko解释需要对生物合成，成岩作用和保存期间碳和氮的形成和转化的基本欣赏。 提出了一系列实验，以阐明生物合成和成岩作用对生物矿物质和沉积物中有机物的分子和稳定同位素组成的影响。 涉及两种浮游有孔虫（Orbulina Universa和Globigerina Bulloides）的增长研究将与Howard Spero博士合作进行，以比较壳蛋白蛋白质氨基酸成分的稳定碳和氮同位素组成与饮食的氨基酸组成。 除了潜在地识别必需氨基酸外，还将评估与营养相互作用相关的同位素分馏的大小。 对化石的生物信号的现实评估需要评估同位素分馏的限制，这些限制可能在成岩作用和开发明确的标准，以评估与保留矩阵可能交换成分的明确标准。 计划进行仿真实验，以评估成岩作用对化石和沉积物中有机物稳定的同位素组成的影响。 具体而言，将尝试评估由水解和嗡嗡声导致的稳定碳和氮同位素分馏的大小。 在保存方面，主要问题仍然是将土著有机化合物与外源性溢出区分开的能力。 The further development of gas chromatography/combustion/isotope ratio mass spectrometry (GC/C/IRMS) for stable nitrogen isotope analysis of amino acid enantiomers in fossils will provide an independent method for verifying the stable carbon isotope analysis of amino acid enantiomers, the development of GC/C/IRMS for stable nitrogen isotope analysis is dependent upon e stablishing isotopically可再现的燃烧技术能够氧化和还原氨基酸的卤代衍生物。 该方法的一个重要测试涉及白垩纪样品中单个氨基酸的D-和l构象体的分子稳定碳和氮同位素分析，其中包括恐龙卵和相关的胚胎骨骼成分。 戴尔·罗素（Dale Russell）博士和杰克·霍纳（Jack Horner）博士从北美和中国的地点提供了这些罕见的样本。 如果同位素信号验证了本土性，则可以使用分子稳定的同位素来建立产生卵的成年人的身份和营养水平。 据我们所知，这项研究还将提供对来自相同化石生物体的壳和骨骼氨基酸成分的分布和稳定同位素组成的首次直接比较。 戴尔·罗素（Dale Russell）还提供了另外一组来自西撒哈拉的白垩纪恐龙样本，以详细研究有机物保存和古生态学。