Search results for "Biomaterials"
showing 10 items of 1265 documents
Biochemical characteristics of the shell soluble organic matrix of some recent Rhynchonelliformea (Brachiopoda).
2005
11 pages; International audience; To build up their shell, brachiopods secrete a mixture of proteins and polysaccharides, collectively called the shell organic matrix. This matrix is supposed to mediate the calcification process by allowing the crystal nucleation and elongation and finally, by stopping the crystal growth. The aim of this work is, firstly, to observe at nanoscale the close relationships between the mineral and the organic phases, and secondly, to characterize the acetic acid-soluble matrices extracted from different articulate brachiopods. Recent articulate brachiopod shells were observed according to a standard procedure, which emphasizes the microstructural details. For th…
Biominéralisation - Des protéines acides peuvent lier le vivant et le minéral.
2011
Rubrique "Questions à l'expert" - Matière; National audience
Biochemical Characterization of the Soluble Organic Matrix of Gastroliths from Decapods.
2005
10 pages; International audience; Gastroliths are disc-shaped calcium storage structures cyclically elaborated by some decapods in their stomach wall. In the present study, we extracted the gastrolith organic matrix from three different decapods, two crayfishes and one lobster, and began to characterize the soluble matrix obtained after decalcification by acetic acid. By using different staining (silver nitrate, Coomassie Blue, Stains-all) after SDS-PAGE, we evidenced that these soluble fractions are rich in polypeptides, some seems common, others are completely different. Among them, putative calcium binding proteins might be present and have to be further characterized. This soluble organ…
Calcification in the Shell of the Freshwater Bivalve Unio pictorum.
2005
8 pages; International audience; The scope of the present study is to elucidate the primary structure of the shell proteins of the mollusk Unio pictorum. This freshwater bivalve exhibits an aragonitic shell with nacro-prismatic microstructures. The acetic acid-soluble matrix of the nacreous layer has been extracted, and analyzed on standard polyacrylamide gel under denaturing conditions. Five main proteins can be observed. Their respective apparent molecular weight is 95, 50, 29, 14 and 10 kDa. The three high molecular weight bands are acidic, glycosylated and bind calcium in vitro. These proteins are purified by preparative SDSPAGE. In addition, these fractions are tested to check their ab…
Il y a nacre et nacre.
2016
1 page - commentaire; National audience
Biomineralization: from fundamentals to biomaterials & environmental issues.
2015
350 pages; International audience
Caspartin: thermal stability and occurrence in mollusk calcified tissues.
2005
8 pages; International audience; The fan mussel Pinna nobilis secretes a two-layered shell, the external layer of which is composed of long calcitic prisms. The dissolution of these prisms releases an assemblage of acidic intracrystalline proteins, among which caspartin, an Asp-rich protein (Marin et al., 2005). A polyclonal antibody raised against purified caspartin was used for estimating its thermal stability, and for investigating the presence of cross-reacting proteins in the shell matrices of several mollusks. In the first case, prisms of Pinna nobilis were heated at 100°C, for one to eleven days. The degradation of caspartin was followed on SDS-PAGE and on Western-blot. The experimen…
'Shellome': Proteins involved in mollusk shell biomineralization - diversity, functions.
2011
18 pages; International audience
The XP-Endo Finisher for the removal of calcium hydroxide paste from root canals and from the apical third
2017
Background The aim was to compare the efficacy of the passive ultrasonic irrigation PUI and the Xp-endo Finisher (FKG-Dentaire, La-Chaux-de-Fonds, Switzerland) in removing the calcium hydroxide paste from root canals and from the apical third. Material and methods Sixty-eight root canals of single-rooted teeth were shaped using the BT-Race files (FKG-Dentaire, La-Chaux-de-Fonds, Switzerland). Ca(OH)2 was placed in all samples except for the negative control group (n=4). Remaining teeth were randomly divided into three groups: G1-Xp (n=30), G2-PUI (n=30) and the positive control group (n=4). Removal procedure consisted of three repeated one-minute-cycles. Samples were split longitudinally, p…
Evidence of atrazine mineralization in a soil from the Nile Delta: Isolation of Arthrobacter sp. TES6, an atrazine-degrading strain
2011
International audience; The s-triazine herbicide atrazine was rapidly mineralized (i.e., about 60% of C-14-ring-labelled atrazine released as (CO2)-C-14 within 21 days) by an agricultural soil from the Nile Delta (Egypt) that had been cropped with corn and periodically treated with this herbicide. Seven strains able to degrade atrazine were isolated by enrichment cultures of this soil. DNA fingerprint and phylogenetic studies based on 165 rRNA analysis showed that the seven strains were identical and belonged to the phylogeny of the genus Arthrobacter (99% similarity with Arthrobacter sp. AD38, EU710554). One strain, designated Arthrobacter sp. strain TES6, degraded atrazine and mineralized…