Bone: ultrastructure, chemistry and isotopes

骨骼由两种成分组成，一种是称为羟基磷灰石(HA)的硬质磷酸钙矿物，另一种是较弱的蛋白质--胶原蛋白。了解这些成分在动物和人类骨骼中是如何编织在一起的，对于了解骨骼的生长发育和骨骼疾病非常重要。我们已经发现，骨骼中的大部分HA是以长而薄的板状形式存在的，这些板状结构包围并强化了胶原蛋白的柱状(纤维)。在我们的研究中，我们将重点研究这种模式的细节，因为它随着年龄和骨骼位置的不同而变化，以及不同物种之间的差异。我们还将深入研究这些富含HA的平板，以了解它们是如何组合在一起的，因为我们也已经表明，它们不是单晶体，而是许多更小晶体的包装。我们还将研究骨骼的另外两个方面。我们已经证明，柠檬酸是骨骼的重要成分，占所有骨骼的2%。它的功能尚不清楚，尽管它可能是维持骨骼晶体质量所必需的。我们将试图找出它是如何进入骨骼的，它位于哪里，它是如何发挥作用的。柠檬酸在死后和埋骨后逐渐消失。我们已经证明，我们可以根据法医骨骼样本的柠檬酸盐浓度来确定死亡时间。我们将尝试确定柠檬酸盐是如何丢失的，以及损失率如何随着埋藏条件的变化而变化，以扩大这种方法在破案中的适用性。此外，我们还将研究氧的稳定同位素比率(18O/16O)在骨骼和牙齿中如何随人们居住的地方而变化，作为追踪人类迁徙的一种方式，并将其应用于解决考古学和法医学中的问题。这是一个协调的、多方面的项目，它应用了来自地球化学、矿物学和材料科学的新方法来研究骨骼。

Bones are built of two components, a hard calcium phosphate mineral called hydroxyapatite (HA), and a weaker protein, collagen. Knowledge of how these components are woven together in animal and human bone is important in understanding the growth and development of bone and in diseases of bone. We have discovered that most of the HA in bone is in the form of long, thin plates which surrounds and reinforce columns (fibrils) of collagen. In our research we will focus on working out the details of this pattern as it varies with age and skeletal location, and between different species. We will also delve inside these HA-rich plates to learn how they are put together, as we have also shown that they are not single crystals but rather packages of many even smaller crystals. We will also study two other aspects of bone. We have shown that citric acid is an important constituent of bone making up as much as 2% of all bones. Its function is still unknown although it is probably required to maintain the qualities of bone crystals. We will try to find how it gets into bone, where it is located, and how it functions. Citrate gradually disappears after death and burial of the bone. We have shown that we can date forensic bone samples from their citrate concentration to tell the time since death. We will try to determine how the citrate is lost and how the rate of loss varies with the conditions of burial, to broaden the applicability of this method in solving crime. Also, we will study how the ratio stable isotopes of oxygen (18O/16O) varies in bones and teeth depending on where people were living, as a way to trace migration of people, and apply this to solve problems in archaeology and forensic science. This is a concerted, multifaceted program which applies novel methods from geochemistry, mineralogy and material science to bear on the study of bone.