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.

Austromegabalanus psittacus barnacle shell structure and proteoglycan localization and functionality

“…However, these authors did not explore the activity of proteoglycans. Such polyanionic macromolecules have been involved in eggshell and crustacean gastrolith structure and formation (Arias and Fernandez, 2008;Arias et al, 2007;Fernández et al, 2012;Luquet et al, 2013).…”

Calcium Deposits in the Crayfish, Cherax quadricarinatus: Microstructure Versus Elemental Distribution

“…They are synthesized in two specialized discoidal areas by epithelial cells between the stomach epithelium and a noncalcified cuticle underlying this epithelium (Travis, 1963;Shechter et al, 2008a;Glazer & Sagi, 2012). The mineral phase, which originates from decalcification of the old carapace, is precipitated within an organic template of chitin-protein fibers tightly linked by protein bridges (Thormann et al, 2012;Luquet et al, 2013; see also Fig. 1).…”

Retrosynthesis of CaCO3 via amorphous precursor particles using gastroliths of the Red Claw lobster (Cherax quadricarinatus)

“…Gastrolith concretions have a flat concave and convex sides related to their anatomical location in the stomach lumen. The occurrence of PG molecules in gastroliths of the crayfish Cherax quadricarinatus and analyses of the ultrastructure and composition of gastroliths from freshwater crayfish utilizing a combination of microscopic and physical techniques have been previously reported (Fernández et al, 2012;Luquet et al, 2013).…”