title: Comparative ultrastructure and carbohydrate composition of gastroliths from astacidae, cambaridae and parastacidae freshwater crayfish (crustacea, decapoda).
abstract: Crustaceans have to cyclically replace their rigid exoskeleton in order to grow. Most of them harden this skeleton by a calcification process. Some decapods (land crabs, lobsters and crayfish) elaborate calcium storage structures as a reservoir of calcium ions in their stomach wall, as so-called gastroliths. For a better understanding of the cyclic elaboration of these calcium deposits, we studied the ultrastructure of gastroliths from freshwater crayfish by using a combination of microscopic and physical techniques. Because sugars are also molecules putatively involved in the elaboration process of these biomineralizations, we also determined their carbohydrate composition. This study was performed in a comparative perspective on crayfish species belonging to the infra-order Astacidea (Decapoda, Malacostraca): three species from the Astacoidea superfamily and one species from the Parastacoidea superfamily. We observed that all the gastroliths exhibit a similar dense network of protein-chitin fibers, from macro- to nanoscale, within which calcium is precipitated as amorphous calcium carbonate. Nevertheless, they are not very similar at the molecular level, notably as regards their carbohydrate composition. Besides glucosamine, the basic carbohydrate component of chitin, we evidenced the presence of other sugars, some of which are species-specific like rhamnose and galacturonic acid whereas xylose and mannose could be linked to proteoglycan components.
authors: Biogéosciences, UMR 6282 CNRS-Université de Bourgogne, 21000 Dijon, France. gilles.luquet@mnhn.fr.
authors: Gilles
authors: G
authors: Luquet
authors: Faculty of Veterinary and Animal Sciences, Universidad de Chile, Santiago, Chile. sofernan@uchile.cl.
authors: María S
authors: MS
authors: Fernández
authors: Biologie des Organismes et Ecosystèmes Aquatiques, UMR MNHN-CNRS 7208- UPMC-IRD 207, Station de Biologie Marine, 29900 Concarneau, France. aicha.badou@mnhn.fr.
authors: Aïcha
authors: A
authors: Badou
authors: Biogéosciences, UMR 6282 CNRS-Université de Bourgogne, 21000 Dijon, France. nathalie.guichard@u-bourgogne.fr.
authors: Nathalie
authors: N
authors: Guichard
authors: Biogéosciences, UMR 6282 CNRS-Université de Bourgogne, 21000 Dijon, France. nathalie.le-roy@u-bourgogne.fr.
authors: Nathalie Le
authors: NL
authors: Roy
authors: UPSP PROXISS, Département Agronomie Environnement, AgroSupDijon, 21000 Dijon, France. m.corneillat@agrosupdijon.fr.
authors: Marion
authors: M
authors: Corneillat
authors: UPSP PROXISS, Département Agronomie Environnement, AgroSupDijon, 21000 Dijon, France. g.alcaraz@agrosupdijon.fr.
authors: Gérard
authors: G
authors: Alcaraz
authors: Faculty of Veterinary and Animal Sciences, Universidad de Chile, Santiago, Chile. jarias@uchile.cl.
authors: José L
authors: JL
authors: Arias