Analysis of shell formation from calcium carbonate crystals in species specific manner

在软体动物中，CaCO_3的生物矿物以壳的形式形成，在物种之间具有极其不同的形态，使物种的分类和鉴定成为可能。壳是遗传调控的生物矿物，由外周膜层和内钙质层组成，内钙质层由叶状层、交叉层、柱状层和珍珠层等多层组成。这些层由CaCO_3组成，但其晶体类型因种类而异；在大多数珍珠贝中，方解石在棱柱状层中，文石在珍珠层中。文石珍珠层被称为珍珠母贝，由直径几百纳米的致密片组成。据报道，它的韧性比用化学方法生产的简单文石晶体大1000倍。除了CaCO_3外，软体动物壳中还含有有机基质蛋白，它们被认为是珠光层韧性的重要组成部分，并在钙化过程中起着关键作用。在这项研究中，我对地幔中表达的基因进行了分析。研究结果如下：1。分离出几个在牡蛎壳中表达的内务基因，并确定了它们的主要结构。从牡蛎胚膜中分离到编码富含甘氨酸蛋白的新基因，并确定了它们的一级结构。利用cdna产生的重组蛋白抑制了碳酸钙的结晶。珍珠素蛋白存在于珍珠贝的珍珠层中，对碳酸钙结晶有抑制作用。在珍珠贝中发现了编码富含甘氨酸蛋白的新基因，并确定了它们的全核苷酸序列。

In molluscs, biominerals of CaCO_3 are formed as shells with extremely divergent morphologies among species, enabling classification and identification of species. Shells are genetically regulated biominerals which consist of an external periostracal layer and an inner calcareous layer which is composed of several layers, such as a foliate, crossed lamellar, prismatic and nacreous layer. These layers are composed of CaCO_3, but their crystal types vary according to species ; in most pearl oysters, calcite in the prismatic layer and aragonite in the nacreous layer. The aragonitic nacreous layer is known as mother-of-pearl and consists of compact tablets of several hundreds nm in diameter. It is reported that its toughness is 1000 times greater than simple aragonite crystals produced by a chemical procedure. In addition to CaCO_3, mollusc shells contain as minor components organic matrix proteins, which are thought to be responsible for the toughness on the nacreous layer and to have some critical roles in calcification. In this research, I carried out analysis of genes expressed in the mantle. The results are as follows :1.Several housekeeping genes that are expressed in the oyster mantle were isolated and their primary structure were determined.2.Novel genes encoding glycine-rich proteins were isolated from the oyster mantle and their primary structure were determined. Recombinant proteins produced using the cDNAs inhibited the calcium carboane crystallization.3.The nacrein protein, which is found in the nacreous layer of the pearl oyster, has inhibitory activity in the calcium carbonate crystallization4.Novel genes encoding glycine-rich proteins in the pearl oyster were discovered and their entire nucleotide sequence were determined.