Search results for "Biomineralization"

The Role of Enzymes in Biomineralization Processes

2010

Microbial origin for pedogenic micrite associated with a carbonate paleosol (Champagne, France)

1999

Abstract Micro-rods have been observed in indurated carbonate horizons (30 cm thick) that overlie a periglacial chalk formation, in contact with the present-day soil (Champagne, France). They are numerous in the upper part of the hardened layers. Variations in micro-rod morphologies are related to progressive biomineralization of organic matter, transforming purely organic rods into calcite. Mineralized rods undergo diagenesis and their arrangement evolves from a random mesh fabric to recrystallized micritic platelets to microsparite. Two types of organic micro-rods have been observed: bacilliform and thread-like bacteria. Mineralogically, micro-rods are low-magnesian calcite. Crystallograp…

Reply to “Mirror Symmetry Breaking” of the Centrosymmetric CaCO3 Crystals with Amino Acids

2008

High yield recombinant production of a self-assembling polycationic peptide for silica biomineralization.

2015

We report the recombinant bacterial expression and purification at high yields of a polycationic oligopeptide, P5S3. The sequence of P5S3 was inspired by a diatom silaffin, a silica precipitating peptide. Like its native model, P5S3 exhibits silica biomineralizing activity, but furthermore has unusual self-assembling properties. P5S3 is efficiently expressed in Escherichia coli as fusion with ketosteroid isomerase (KSI), which causes deposition in inclusion bodies. After breaking the fusion by cyanogen bromide reaction, P5S3 was purified by cation exchange chromatography, taking advantage of the exceptionally high content of basic amino acids. The numerous cationic charges do not prevent, b…

Inside Cover: Phase Selection of Calcium Carbonate through the Chirality of Adsorbed Amino Acids (Angew. Chem. Int. Ed. 29/2007)

2007

Biosilica

2012

Biomineralization, biosilicification in particular (i.e. the formation of biogenic silica, SiO(2)), has become an exciting source of inspiration for the development of novel bionic approaches following 'nature as model'. Siliceous sponges are unique among silica-forming organisms in their ability to catalyze silica formation using a specific enzyme termed silicatein. In this study, we review the present state of knowledge on silicatein-mediated 'biosilica' formation in marine demosponges, the involvement of further molecules in silica metabolism and their potential applications in nano-biotechnology and bio-medicine. While most forms of multicellular life have developed a calcium-based skel…

Orchestin, a calcium-binding phosphoprotein, is a matrix component of two successive transitory calcified biomineralizations cyclically elaborated by…

2003

Orchestia cavimana is a crustacean that cyclically replaces its calcified cuticle during molting cycles in order to grow. Its terrestrial way of life requires storage of calcium during each premolt period, as calcareous concretions, in tubular diverticula of the midgut. During the postmolt period the stored calcium is reabsorbed and is translocated through the storage organ epithelium as calcified small spherules. In a previous study, we sequenced and characterized a remarkable component of the organic matrix of the premolt storage structures, Orchestin, which is a calcium-binding phosphoprotein. In this paper, we analyzed the spatiotemporal expression of the orchestin gene by Northern blot…

Spine and test skeletal matrices of the Mediterranean sea urchinArbacia lixula- a comparative characterization of their sugar signature

2015

15 pages; International audience; Calcified structures of sea urchins are biocomposite materials that comprise a minor fraction of organic macromolecules, such as proteins, glycoproteins and polysaccharides. These macromolecules are thought to collectively regulate mineral deposition during the process of calcification. When occluded, they modify the properties of the mineral. In the present study, the organic matrices (both soluble and insoluble in acetic acid) of spines and tests from the Mediterranean black sea urchin Arbacia lixula were extracted and characterized, in order to determine whether they exhibit similar biochemical signatures. Bulk characterizations were performed by mono-di…

Gene expression and stress response in sea urchin embryos with skeleton defects caused by magnesium deprivation.

2012

Echinoderms have an extensive endoskeleton composed of magnesian calcite, a form of calcium carbonate that contains small amounts of magnesium carbonate and occluded matrix proteins [1]. In the frame of the Biomintec European Project focused on the understanding of basic biomineralization mechanisms for the design of novel strategies in nano-biotechnology, we studied the effects of magnesium deprivation on Arbacia lixula sea urchin embryo development. Embryos were morphologically monitored, evaluating developmental abnormalities at different endpoints (3, 6, 24, 48 and 72 hours). In parallel, the spatial transcriptional levels of a skeleton matrix protein (msp130) and the protein synthesis …

The shell matrix of the freshwater mussel Unio pictorum (Paleoheterodonta, Unionoida). Involvement of acidic polysaccharides from glycoproteins in na…

2007

13 pages; International audience; Among molluscs, the shell biomineralization process is controlled by a set of extracellular macromolecular components secreted by the calcifying mantle. In spite of several studies, these components are mainly known in bivalves from only few members of pteriomorph groups. In the present case, we investigated the biochemical properties of the aragonitic shell of the freshwater bivalve Unio pictorum (Paleoheterodonta, Unionoida). Analysis of the amino acid composition reveals a high amount of glycine, aspartate and alanine in the acid-soluble extract, whereas the acid-insoluble one is rich in alanine and glycine. Monosaccharidic analysis indicates that the in…