title: Enamel-like apatite crown covering amorphous mineral in a crayfish mandible.
abstract: Carbonated hydroxyapatite is the mineral found in vertebrate bones and teeth, whereas invertebrates utilize calcium carbonate in their mineralized organs. In particular, stable amorphous calcium carbonate is found in many crustaceans. Here we report on an unusual, crystalline enamel-like apatite layer found in the mandibles of the arthropod Cherax quadricarinatus (freshwater crayfish). Despite their very different thermodynamic stabilities, amorphous calcium carbonate, amorphous calcium phosphate, calcite and fluorapatite coexist in well-defined functional layers in close proximity within the mandible. The softer amorphous minerals are found primarily in the bulk of the mandible whereas apatite, the harder and less soluble mineral, forms a wear-resistant, enamel-like coating of the molar tooth. Our findings suggest a unique case of convergent evolution, where similar functional challenges of mastication led to independent developments of structurally and mechanically similar, apatite-based layers in the teeth of genetically remote phyla: vertebrates and crustaceans.
authors.affiliation: Department of Biotechnological Engineering, Ben-Gurion University, 84105 Beer-Sheva, Israel.
authors.forename: Shmuel
authors.initials: S
authors.lastname: Bentov
authors.forename: Paul
authors.initials: P
authors.lastname: Zaslansky
authors.forename: Ali
authors.initials: A
authors.lastname: Al-Sawalmih
authors.forename: Admir
authors.initials: A
authors.lastname: Masic
authors.forename: Peter
authors.initials: P
authors.lastname: Fratzl
authors.forename: Amir
authors.initials: A
authors.lastname: Sagi
authors.forename: Amir
authors.initials: A
authors.lastname: Berman
authors.forename: Barbara
authors.initials: B
authors.lastname: Aichmayer
mesh_terms: D000818:Animals; D001031:Apatites / Q000032:analysis* / Q000378:metabolism; D003400:Astacoidea / Q000737:chemistry* / Q000378:metabolism; D005075:Biological Evolution; D002119:Calcium Carbonate / Q000032:analysis; D003743:Dental Enamel / Q000737:chemistry*; D017886:Durapatite / Q000032:analysis / Q000378:metabolism; D008334:Mandible / Q000737:chemistry / Q000378:metabolism; D008963:Molar / Q000737:chemistry / Q000378:metabolism
chemical_list: D001031:Apatites; D017886:Durapatite; D002119:Calcium Carbonate