Nitrogen isotopes in tooth enamel record diet and trophic level enrichment: Results from a controlled feeding experiment
Nitrogen isotopes in tooth enamel record diet and trophic level enrichment: Results from a controlled feeding experiment
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DOI：
10.1016/j.chemgeo.2020.120047
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发表时间：
2021-01-16
期刊：
影响因子：
3.9
通讯作者：
Martinez-Garcia, Alfredo
中科院分区：
文献类型：
--
作者：
Leichliter, Jennifer N.;Ludecke, Tina;Martinez-Garcia, Alfredo
氮同位素比值（Δ N-15）是研究陆地和海洋食物网中动物的饮食和营养行为的一个成熟工具。到目前为止，化石中的N-15值主要是在从骨骼或牙本质中提取的胶原蛋白中测量的，这些胶原蛋白容易降解，很少保存在较深的时间（> 100，000年）。相比之下，牙釉质有机物质受到羟基磷灰石矿物结构的保护，不受成岩作用的影响，因此通常在地质时期被保存下来。然而，由于氮含量低（=比传统方法少100倍的氮）。为了证明Δ N-15（釉质）值记录饮食和营养行为，我们用大鼠和豚鼠（n = 37）进行了对照喂养实验。我们确定牙釉质中的氮浓度（x（-）= 5.0 + 1.0 nmol/mg）足以用于使用>= 5 mg未处理的釉质粉末的Δ N-15（釉质）分析。釉质的氮同位素组成反映了饮食与富集（Δ N-15（釉质饮食））约。2-4千分之几Δ N-15（釉质）值在饮食组之间显著不同，并且清楚地记录了从实验前饮食到实验饮食的转变。所需的小样本量（
Nitrogen isotope ratios (delta N-15) are a well-established tool for investigating the dietary and trophic behavior of animals in terrestrial and marine food webs. To date, delta N-15 values in fossils have primarily been measured in collagen extracted from bone or dentin, which is susceptible to degradation and rarely preserved in deep time (>100,000 years). In contrast, tooth enamel organic matter is protected from diagenetic alteration by the mineral structure of hydroxyapatite and thus is often preserved over geological time. However, due to the low nitrogen content (= 100 times less nitrogen than traditional approaches. To demonstrate that delta N-15(enamel) values record diet and trophic behavior, we conducted a controlled feeding experiment with rats and guinea pigs (n = 37). We determined that nitrogen concentration in tooth enamel (x(-) = 5.0 + 1.0 nmol/mg) is sufficient for delta N-15(enamel) analyses with >= 5 mg untreated enamel powder. The nitrogen isotope composition of enamel reflects diet with an enrichment (Delta N-15(enamel-diet)) of ca. 2-4 parts per thousand. delta N-15(enamel) values differ significantly between dietary groups and clearly record a shift from pre-experimental to experimental diet. The small sample size required (