SGER: Stable Isotope Fingerprinting: A Novel Approach to Identifying Amino Acid Biosynthetic Sources, Using Stable Isotope Variation Among Amino Acids.

了解营养流是有机生物学和生态系统生态学的中心目标。例如，在营养生理学中，研究人员才刚刚开始认识到动物如何满足必需氨基酸和脂肪酸的需求的复杂性，以及满足这些需求如何产生生理上的相互依赖性。 在北极生态系统中，氨基酸是北方植物群落氮的关键来源，但它们如何供给土壤尚不清楚。 植物和根真菌（菌根）之间的营养关联很常见，但伙伴之间营养交换的细节尚不清楚。 在所有这些情况下，进展都受到追踪养分交换的可用工具的限制。 这项研究开发了一种利用氨基酸碳同位素特征中生物代谢产生的变化来追踪氨基酸生物合成来源的新方法。这些同位素特征套件可以被认为是生物合成的“指纹”，并且这些指纹可以诊断产生它们的生物体类型。 拟议的研究将表征选定微生物、植物和真菌的氨基酸同位素指纹。 这些生物体可以从头合成蛋白质中发现的所有二十种氨基酸，并有可能为动物、土壤营养库或共生伙伴提供氨基酸。 如果这些指纹被证明是生物合成来源的稳健、可重复的指标，它们将改变研究人员解决现有技术无法回答的自然系统中养分流动问题的能力。这样的工具将引起研究生理生态学、进化生态学、植物-昆虫相互作用、植物生物学、生态系统生态学和生物地球化学的科学家的极大兴趣。 用于测量氨基酸同位素特征的分析变得越来越可用。 然而，由于缺乏比较数据，越来越多的文献充斥着未经验证的假设。 因此，这项研究将显着增进我们对生物体内部和生物体之间氨基酸特征变异性的理解，并将为具有广泛适用性的方法论奠定基础。该研究项目将涉及对一名研究生进行开发这种新颖工具的培训。

Understanding nutrient flow is a central goal of both organismal biology and ecosystem ecology. In nutritional physiology, for example, researchers are only starting to appreciate the complexity of how animals meet requirements for essential amino acids and fatty acids, and how meeting those requirements can generate physiological interdependency. In arctic ecosystems, amino acids are a key source of nitrogen for boreal plant communities, but how they are supplied to soil is unclear. Nutritional associations between plants and root-fungi (mycorrhizae) are common, but the details of nutrient exchange between the partners are not well known. In all these cases, progress is limited by the available tools for tracing nutrient exchange. This research develops a new approach to tracing amino acid biosynthetic sources, using the variation generated by organismal metabolism in the carbon isotopic signatures of amino acids. These suites of isotopic signatures can be thought of as a biosynthetic "fingerprint," and these fingerprints may be diagnostic of the type of organism that produced them. The proposed research will characterize the amino acid isotopic fingerprints of select microorganisms, plants, and fungi. These organisms can synthesize de novo all twenty amino acids found in proteins, and potentially supply amino acids to animals, soil nutrient pools, or symbiotic partners. If these fingerprints prove to be robust, reproducible indicators of biosynthetic sources, they would transform the ability of researchers to address questions about nutrient flow in natural systems that cannot be answered with present technology. Such a tool will be of great interest to scientists studying physiological ecology, evolutionary ecology, plant-insect interactions, plant biology, ecosystem ecology, and biogeochemistry. The analyses used to measure isotope signatures in amino acids are becoming increasingly available. However, the lack of comparative data has contributed to a growing literature that is rife with poorly validated assumptions. Thus, this research will significantly advance our understanding of the variability of amino acid signatures within and among organisms, and will provide the foundation for a methodology with wide ranging applicability. This research project will involve training of a graduate student in the development of this novel tool.