Biochemical Characterization of the Soluble Organic Matrix of Gastroliths from Decapods.
Résumé
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 organic matrix also interacts in vitro with calcite crystals growth, suggesting its involvement in the calcium carbonate precipitation. The main conclusion of this preliminary study is that close species from the same order of animals have developed very similar calcium storage strategies by elaborating morphologically identical structures, but different in their molecular composition.