Calcium carbonate biomineral

Calcium carbide, 11 182-183 neutron diffraction studies on, 8 234 Calcium carbonate, biomineralization, 36 163-167... 

Another important point about calcium carbonate biomineralization is that more than one of the three polymorphs may be present in close proximity within an individual sample and each may be a different calcium carbonate polymorph (mollusks provide such an example), or the mineral may change over time. In many species the larval stage is aragonitic, while the adult biomineral is calcite. The different minerals in biomineralized tissues play specific roles in the proper functioning of the organism. 

What Genes and Genomes Tell Us about Calcium Carbonate Biomineralization... 

Fricke M, Volkmer D (2007) Crystallization of Calcium Carbonate Beneath Insoluble Mono-layers Suitable Models of Mineral-Matrix Interactions in Biomineralization 270 1-41 Fujimoto D, see Tamura R (2007) 269 53-82... 

The bones and teeth of humans and other vertebrate animals, for example, consist mainly of a composite material made up of an organic substance, collagen, and a biomineral, calcium carbonate phosphate (see Textboxes 32 and 61). The latter, which makes up about two-thirds of the total dry weight of bone, is composed of calcium phosphate containing between 4-6% calcite (composed of calcium carbonate) as well as small amounts of sodium, magnesium, fluorine, and other trace elements. The formula Ca HPChXPChMCChXOH) approximately represents its composition its crystal structure is akin to that... 

As mentioned earlier, biological systems have developed optimized strategies to design materials with elaborate nanostructures [6]. A straightforward approach to obtaining nanoparticles with controlled size and organization should therefore rely on so-called biomimetic syntheses where one aims to reproduce in vitro the natural processes of biomineralization. In this context, a first possibility is to extract and analyze the biological (macro)-molecules that are involved in these processes and to use them as templates for the formation of the same materials. Such an approach has been widely developed for calcium carbonate biomimetic synthesis [13]. In the case of oxide nanomaterials, the most studied system so far is the silica shell formed by diatoms [14]. 

CALCIUM-BASED BIOMINERALS CALCIUM CARBONATES IN ASCIDIANS AND MOLLUSCS... 

Finally, it is intriguing that in terms of biomineralization, invertebrates have based their reliance on calcium carbonates, while vertebrates appear to have used almost exclusively calcium phosphate. We say almost, because, while the use of calcium phosphates for biomineralization is an invention of some vertebrates, they still use calcium carbonate for the formation of otoliths4 of the inner ear. It remains to be established if the equivalent of the gene starmaker required for otolith formation in zebrafish has homologues among invertebrates. 

CALCIUM/CALMODULIN-DEPENDENT PROTEIN KINASE Calcium carbonate (CaCOs), BIOMINERALIZATION SOLUBILITY PRODUCT Calcium hydroxide (Ca(OH)2),... 

Biomineralization, 36 137-139 calcium carbonate, 36 163-167 in algae, 36 166-167 gravity sensors, 36 164-166 carbonate/sulfate mineralization mechanisms, 36 171-175... 

Meldrum, 2002), the elaborately shaped spicules in ascidians, and finely the sculpted coccolith shells in coccolithophores (Mann, 2001). For silica structure, the diatoms produce the most exquisite siliceous cell wall (Sumper and Brunner, 2006). Also the calcium phosphate in bone shows a highly regulated organization and arrangement. Interestingly, avians have two main biomineralization systems, one produces calcium carbonate for egg shell and the other produces calcium phosphate for bone (Bauerlein, 2000 Mann, 2001). 

Addadi, L., Joester, D., Nudelman, F., and Weiner, S. "Mollusk shell formation A source of new concepts for understanding biomineralization processes". Chem. Eur.. 12(4), 981-987 (2006). Ajikumar, P.K., Lakshminarayanan, R., and Valiyaveettil, S. "Controlled deposition of thin films of calcium carbonate on natural and synthetic templates". Crystal Growth Des. 4(2), 331-335 (2004). 

Calcium carbonate minerals (CaCOs) are ubiquitous in biomineralizing systems, since they are in the skeletons of organisms ranging from bacteria and algae to humans, most commonly as calcite (rhomboedral) or aragonite (orthorhombic). Thus, their structures and compositions are highly diversified. Here, only some examples are discussed. 

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