SGER: An Amino Acid-based Isotopic Method for Studying the Dynamics of Ancient Ecosystems

SGER：一种用于研究古代生态系统动力学的基于氨基酸的同位素方法

• 批准号: 0845015
• 负责人: David Fastovsky
• 金额: $ 2.34万
• 依托单位: University of Rhode Island
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2009
• 资助国家: 美国
• 起止时间: 2009-03-01 至 2012-02-29
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0845015&HistoricalAwards=false
• 关键词: SGER; Amino; Acid; based; Isotopic

An amino acid-based isotopic method for studying the dynamics of ancient ecosystemsPI: David E. Fastovsky; Co-PIs: Rebecca S. Robinson; Steven L. D¡¦HondtThe idea behind this proposal is to develop a method by which we can measure the nitrogen isotopic composition of amino acids from fossil bones and teeth. It has been shown that the amount of 15N/14N (which we measure as ?Ô15N) increases each trophic step in a food chain. This means in effect that the 15N/14N ratio is lowest among primary producers (in the terrestrial realm, this generally means plants), and increases in those organisms that eat the primary producers, and increases even further in those animals that eat the animals that eat the primary producers. So the ?Ô15N signature is actually a way to measure at which levels long-extinct organisms functioned in long-extinct ecosystems.The mechanics of the development of this technique, which is in fact the point of this proposal, is fraught with problems. Most significant among these are contamination and volume. The contamination problem is the same one that plagues all studies of ancient molecules: there is a very real possibility that the ?Ô15N numbers that we obtain could come from younger organisms ¡V possibly even those living today ¡V and if so their ?Ô15N signatures would obviously be wrong. To avoid this possibility, we would like to obtain our nitrogen from known molecules. We have chosen to use an amino acid signature profile for each tooth, which would tell us that we are at least looking at ancient, preserved molecules. This takes us to the volume problem, because if we are looking at the ?Ô15N signature for just a particular series of identifiable amino acids, then we are obviously required to deal with much smaller samples than if we were looking at the bulk, or total, ?Ô15N signature of a particular tooth or bone. Moreover, during the degradation that takes place as molecules age, certain amino acids are preferentially maintained while others are lost. By targeting of specific amino acids (preferably more than one) and tracing their ?Ô15N signatures through a food web, we will provide a much more reliable picture of dietary relationships than traditional bulk-organic methods allow.The fractionation of nitrogen isotopes as a record of trophic position has been repeatedly demonstrated for both marine and terrestrial ecosystems. With the development of the technique this proposal supports, we anticipate having a precise isotopic tool that identifies (and avoids) problems due to alteration or contamination of fossil material. For this reason, the technique has broad applications for studying ancient ecosystems.

一种基于氨基酸的同位素方法，用于研究古代生态系统的动力学。作者声明：Rebecca S.罗宾逊; Steven L. D.这个提议背后的想法是开发一种方法，通过这种方法我们可以测量骨骼和牙齿化石中氨基酸的氮同位素组成。 已经表明，15 N/14 N的量（我们测量为？15 N）增加了食物链中的每一个营养级。 这实际上意味着，15 N/14 N比率在初级生产者中最低（在陆地领域，这通常指植物），并且在那些吃初级生产者的生物体中增加，并且在那些吃吃初级生产者的动物的动物中进一步增加。 所以？15 N签名实际上是一种测量长期灭绝的生物在长期灭绝的生态系统中发挥作用的方法。这项技术的发展机制，实际上也是这项建议的重点，充满了问题。 其中最重要的是污染和数量。 污染问题是困扰所有古代分子研究的同一个问题：有一个非常真实的可能性，即？我们获得的15 N个数字可能来自更年轻的生物体，甚至可能来自今天的生物体，如果是这样的话，它们的生命可能会更年轻。第15章显然是错的 为了避免这种可能性，我们希望从已知分子中获得氮。 我们选择对每颗牙齿使用氨基酸特征谱，这将告诉我们，我们至少正在寻找古老的、保存下来的分子。 这就把我们带到了体积问题，因为如果我们看？如果我们只针对一系列特定的可识别氨基酸，那么我们显然需要处理的样本要比我们研究的大部分或全部样本小得多？特定牙齿或骨骼的15 N签名。 此外，在随着分子老化而发生的降解过程中，某些氨基酸优先保留，而其他氨基酸则丢失。通过靶向特定的氨基酸（最好是一个以上）和跟踪他们的？通过食物网的15 N签名，我们将提供一个更可靠的图片饮食关系比传统的散装有机方法allow.The分馏的氮同位素作为营养位置的记录已被反复证明为海洋和陆地生态系统。 随着这项建议所支持的技术的发展，我们预计会有一种精确的同位素工具，可以识别（并避免）由于化石材料的改变或污染而引起的问题。 因此，该技术在研究古代生态系统方面具有广泛的应用。