title: Spine and test skeletal matrices of the Mediterranean sea urchin Arbacia lixula--a comparative characterization of their sugar signature.
abstract: 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-dimensional SDS/PAGE, FT-IR spectroscopy, and an in vitro crystallization assay. We concentrated our efforts on characterization of the sugar moieties. To this end, we determined the monosaccharide content of the soluble and insoluble organic matrices of A. lixula spines and tests by HPAE-PAD, together with their respective lectin-binding profiles via enzyme-linked lectin assay. Finally, we performed in situ localization of N-acetyl glucosamine-containing saccharides on spines and tests using gold-conjugated wheatgerm agglutinin. Our data show that the test and spine matrices exhibit different biochemical signatures with regard to their saccharidic fraction, suggesting that future studies should analyse the regulation of mineral deposition by the matrix in these two mineralized structures in detail. This study re-emphasizes the importance of non-protein moieties, i.e. sugars, in calcium carbonate systems, and highlights the need to clearly identify their function in the biomineralization process.
authors.affiliation: Department of Zoology, Institute of Biomaterials and Biomolecular Systems, University of Stuttgart, Germany.
authors.forename: Julia M
authors.initials: JM
authors.lastname: Kanold
authors.affiliation: UMR CNRS 6282 Biogéosciences, Bâtiment des Sciences Gabriel, Université de Bourgogne, Dijon, France.
authors.forename: Nathalie
authors.initials: N
authors.lastname: Guichard
authors.affiliation: UMR CNRS 6282 Biogéosciences, Bâtiment des Sciences Gabriel, Université de Bourgogne, Dijon, France.
authors.forename: Françoise
authors.initials: F
authors.lastname: Immel
authors.affiliation: Institut de Chimie Moléculaire de l'Université de Bourgogne, UMR CNRS 6302, Faculté des Sciences Mirande, Université de Bourgogne, Dijon, France.
authors.forename: Laurent
authors.initials: L
authors.lastname: Plasseraud
authors.affiliation: Unité Propre Soutien de Programme PROXISS, Département Agronomie Environnement AgroSupDijon, Dijon Cedex, France.
authors.forename: Marion
authors.initials: M
authors.lastname: Corneillat
authors.affiliation: Unité Propre Soutien de Programme PROXISS, Département Agronomie Environnement AgroSupDijon, Dijon Cedex, France.
authors.forename: Gérard
authors.initials: G
authors.lastname: Alcaraz
authors.affiliation: Department of Zoology, Institute of Biomaterials and Biomolecular Systems, University of Stuttgart, Germany.
authors.forename: Franz
authors.initials: F
authors.lastname: Brümmer
authors.affiliation: UMR CNRS 6282 Biogéosciences, Bâtiment des Sciences Gabriel, Université de Bourgogne, Dijon, France.
authors.forename: Frédéric
authors.initials: F
authors.lastname: Marin
mesh_terms: D000373:Agglutinins / Q000378:metabolism*; D000818:Animals; D047308:Arbacia / Q000378:metabolism*; D002119:Calcium Carbonate / Q000378:metabolism*; D004591:Electrophoresis, Polyacrylamide Gel; D008522:Mediterranean Sea; D008855:Microscopy, Electron, Scanning; D012617:Sea Urchins / Q000378:metabolism; D017550:Spectroscopy, Fourier Transform Infrared
chemical_list: D000373:Agglutinins; D002119:Calcium Carbonate
keywords: biomineralization; echinoid; lectin assay; organic matrix; saccharide