Crystallography for biology - as easy as EBSD

生命系统对其矿物结构的形成进行精细的控制，产生的结构具有各种功能，例如保护双壳类贝壳、鸟蛋的胚胎室和脊椎动物的骨骼支持。尽管生物防治知识备受追捧，但在很大程度上，人们对生物防治知之甚少。在材料科学和冶金学中，科学家使用一种名为电子背散射衍射(EBSD)的技术来详细探测复杂材料。EBSD包括向倾斜的样品发射一束电子。样品结构中的平面将电子束分开，破碎的电子束被反弹并在屏幕上成像。这幅图告诉我们这个结构是由什么组成的，以及它的方位。申请人一直将EBSD应用于生命系统产生的矿物的分析，取得了很大的效果。关于无脊椎动物生物力学的重要信息已经获得。此外，为了提高我们对这种生物防治的理解，还得到了关于应解决哪些问题的澄清。许多人开始意识到EBSD分析在解决生物科学问题方面的巨大潜力，这一事实表明了这种应用的必要性。申请人发现，EBSD分析在迄今评估的所有生物矿物中并不是同样成功，这进一步加强了对该项目的需求。本项目旨在评估含有方解石和文石两种不同形态碳酸钙的紫贻贝贝壳中的重要样品制备条件：树脂类型、最后抛光阶段的持续时间和碳层厚度。这一初步条件调查将用于确定更广泛的生物矿物调查中的参数，该调查将包括其他碳酸钙生物矿物、腕足动物、珊瑚和苔藓动物以及磷酸钙(磷灰石)生物矿物，即腕足类舌形动物Anatina的外壳和商业上可获得的家禽的股骨。这项更大规模的调查还将量化有机和微量元素的组成，以便在一系列生物矿物系统中确定可能影响结晶学及其控制的因素。这两项调查将确定对生物结构进行EBSD分析的最佳条件，并将确定EBSD分析的限度。这两套知识对于有效地将这一强大的技术转移到生物科学是必不可少的。

Living systems exert exquisite control on the formation of their mineral structures producing structures that perform various functions such as protection in bivalve shells, embryonic chamber in bird eggs and skeletal support in vertebrates for example. To a great extent, the biological control exerted is poorly understood although the knowledge is highly sought after. In materials science and metallurgy, scientists probe complex materials in great details using a technique called Electron Back Scattered Diffraction (EBSD). EBSD involves firing a beam of electrons at a tilted sample. The planes within the structure of the samples, split the electron beam and the fragmented beam is bounced back and imaged on a screen. The image tells us what the structure is made of and its orientation. The applicant has been applying EBSD to the analysis of minerals produced by living systems to great effect. Already important information on the biomechanics of invertebrates has been obtained. In addition, clarification has been obtained regarding which questions should be addressed in order to improve our understanding of this biological control. The need for this application is apparent by the fact that many people are beginning to become aware of the huge potential of EBSD analysis to address questions in biological sciences. The need for this project is further heightened by the discovery by the applicant that EBSD analyses are not equally successful in all biominerals assessed thus far. This project aims to assess the important sample preparation conditions; resin type, duration of final polishing stage and thickness of carbon coat, in the shell of te hcommon blue mussel, Mytilus edulis which contains two polymorphs of calcium carbonate: calcite and aragonite. This initial survey of conditions will be used to define parameters in a wider biomineral survey that will include other calcium carbonate biominerals, brachiopods, corals and bryozoans as well as calcium phosphate (apatite) biominerals, namely the shell of the brachiopod Lingula anatina and the femur of commercially available domestic fowl. This larger survey will also quantify the organic and trace element composition so that the factors that may influence crystallography and its control may be identified in a range of biomineral systems. These two surveys will determine the optimal conditions for EBSD analysis of biogenic structures and will identify the limits of EBSD analysis. Both sets of knowledge are essential for the effective transfer of this powerful technique to biological sciences.