Evans L A, Alvarez R
Department of Chemistry, Materials and Forensic Science, University of Technology, Sydney, New South Wales, Australia.
J Biol Inorg Chem. 1999 Apr;4(2):166-70. doi: 10.1007/s007750050300.
The radula in a group of molluscan invertebrates, the chitons (Polyplacophora), is a ribbon-like apparatus used for feeding and which bears a series of distinctive mineralized teeth called the major lateral teeth. While some chiton species deposit only iron biominerals in these teeth, many others deposit both iron and calcium. In this study, the calcium biomineral in the teeth of one of the latter types of species, the Australian east-coast chiton, Chiton pelliserpentis, has been isolated and examined for the first time. Spectroscopic and crystallographic techniques have identified the biomineral as a carbonate-substituted apatite with significant fluoride substitution also likely. Fourier-transform infrared and laser Raman spectroscopy indicated that the carbonate content was less than that of either bovine tibia cortical bone or human tooth enamel. X-ray diffraction analysis showed the biomineral to be poorly crystalline due to small crystal size and appreciable anionic substitution. The lattice parameters were calculated to be a = 9.382 A and c = 6.883 A, which are suggestive of a fluorapatite material. It is postulated that structural and biochemical differences in the tooth organic matrix of different chiton species will ultimately determine if the teeth become partly calcified or iron mineralized only.
在一类软体动物无脊椎动物石鳖（多板纲）中，齿舌是一种带状器官，用于进食，上面长有一系列独特的矿化齿，称为主要侧齿。虽然一些石鳖物种仅在这些牙齿中沉积铁生物矿物，但许多其他物种同时沉积铁和钙。在本研究中，首次分离并检测了后一种类型物种之一——澳大利亚东海岸石鳖（Chiton pelliserpentis）牙齿中的钙生物矿物。光谱和晶体学技术已将该生物矿物鉴定为一种可能也有大量氟取代的碳酸根取代磷灰石。傅里叶变换红外光谱和激光拉曼光谱表明，其碳酸盐含量低于牛胫骨皮质骨或人类牙釉质。X射线衍射分析表明，由于晶体尺寸小和可观的阴离子取代，该生物矿物结晶性较差。计算出的晶格参数为a = 9.382 Å和c = 6.883 Å，这表明是一种氟磷灰石材料。据推测，不同石鳖物种牙齿有机基质的结构和生化差异最终将决定牙齿是部分钙化还是仅铁矿化。
