Department of Earth Sciences, Centre for Human Evolution Research, Natural History Museum, Cromwell Road, London, SW7 5BD, UK; Department of Cell and Developmental Biology, University College London, Gower Street, London, WC1E 6BT, UK.
Department of Human Evolution, Max Planck Institute for Evolutionary Anthropology, Deutscher Platz 6, D-04103, Leipzig, Germany; PACEA, UMR 5199-CNRS, Université de Bordeaux, Bâtiment B8, Allée Geoffroy Saint-Hilaire, CS 50023, 33615, Pessac Cedex, France.
Arch Oral Biol. 2020 Nov;119:104879. doi: 10.1016/j.archoralbio.2020.104879. Epub 2020 Aug 29.
Dental hard tissues contain trace elements of both dietary and environmental origin. One objective was to demonstrate that a longitudinal record of synchronous Sr incorporation into enamel and dentine can be retrieved from museum specimens of once-free-living endangered species. Further objectives were to quantify sudden fluctuations in Sr concentration and estimate the extent of Sr overprinting back into dentine and enamel formed prior to the time of Sr ingestion.
Daily incremental markings were used to determine rates and times of tooth formation and synchrotron X-ray fluorescence of the same polished ground sections to image Sr distribution in a male and a female orangutan canine. The X-ray beam was monochromatised to 17.0 keV and focused to 500 × 500 nm. Scans were performed at either 25.0 or 5.0 μm resolution.
Baseline Sr levels ranged between 215-750 ppm. Multiple short, intense Sr labels reaching 750- 1,625 ppm occurred randomly throughout 15-22 years of tooth formation. In dentine, Sr concentration increased gradually away from the EDJ, while in enamel, it reduced towards the enamel surface. Using daily incremental markings, Sr overprinting into earlier formed dentine and enamel was estimated to be ∼12-45 days. There was no evidence of Sr overprinting by maturational ameloblasts.
A good record of growth and trace element incorporation into tooth tissues can be retrieved from museum specimens. Short, intense Sr labels were equally well time-resolved in enamel and dentine and could be distinguished from more diffuse background levels. Enamel maturation appears to have no quantifiable effect.
牙体硬组织包含饮食和环境来源的微量元素。目的之一是证明可以从曾经自由生活的濒危物种的博物馆标本中获取同步 Sr 纳入釉质和牙本质的纵向记录。进一步的目的是量化 Sr 浓度的突然波动，并估计 Sr 回印到形成之前的牙本质和釉质的程度在 Sr 摄入的时间。
使用每日增量标记来确定牙齿形成的速率和时间，并对同一抛光磨片进行同步加速器 X 射线荧光分析，以在雄性和雌性猩猩犬齿中成像 Sr 分布。X 射线束被单色化为 17.0keV，并聚焦到 500nm×500nm。扫描以 25.0 或 5.0μm 分辨率进行。
基线 Sr 水平在 215-750ppm 之间。在 15-22 年的牙齿形成过程中，多个短暂而强烈的 Sr 标记随机达到 750-1625ppm。在牙本质中，Sr 浓度逐渐远离 EDJ 增加，而在釉质中，它向釉质表面减少。使用每日增量标记，估计 Sr 回印到早期形成的牙本质和釉质约为 12-45 天。没有证据表明 Sr 被成熟的成釉细胞回印。
可以从博物馆标本中获取关于牙齿组织生长和微量元素纳入的良好记录。在釉质和牙本质中，短暂而强烈的 Sr 标记同样可以很好地时间分辨，并且可以与更弥散的背景水平区分开来。牙本质成熟似乎没有可量化的影响。
