title: Mineral homeostasis and regulation of mineralization processes in the skeletons of sharks, rays and relatives (Elasmobranchii).
abstract: Sharks, rays and other elasmobranch fishes are characterized by a skeletal type that is unique among living vertebrates, comprised predominantly of an unmineralized cartilage, covered by a thin outer layer of sub-millimeter, mineralized tiles called tesserae. The mineralized portion of the skeleton appears to grow only by apposition, adding material at the edges of each tessera; maintenance of non-mineralized joints between tesserae is therefore vital, with precise control of mineral deposition and inhibition at the many thousands of growth fronts in the skeleton. Yet, we have only scattered evidence as to how the elasmobranchs mineralize and grow their skeletons. In this review, we take an "environment to skeleton" approach, drawing together research from a vast range of perspectives to track calcium and phosphate from the typical elasmobranch habitats into and through the body, to their deposition at tesseral growth fronts. In the process, we discuss the available evidence for skeletal resorption capability, mineral homeostasis hormones, and nucleation inhibition mechanisms. We also outline relevant theories in crystal nucleation and typical errors in measurements of serum calcium and phosphate in the study of vertebrate biology. We assemble research that suggests consensus in some concepts in elasmobranch skeletal development, but also highlight the very large gaps in our knowledge, particularly in regards to endocrine functional networks and biomineralization mechanisms. In this way, we lay out frameworks for future directions in the study of elasmobranch skeletal biology with stronger and more comparative links to research in other disciplines and into other taxa.
authors.affiliation: Department Biomaterials, Max Planck Institute of Colloids & Interfaces, Am Muehlenberg 1, 14424 Potsdam, Germany. Electronic address: mason.dean@mpikg.mpg.de.
authors.forename: Mason N
authors.initials: MN
authors.lastname: Dean
authors.affiliation: Department of Biology, Wheaton College, Norton, MA 02766, USA.
authors.forename: Laura
authors.initials: L
authors.lastname: Ekstrom
authors.affiliation: Institute of Biochemistry and Nutrition Faculty of Agricultural, Food and Environmental Sciences, The Hebrew University, P.O.B. 12, Rehovot 76100, Israel.
authors.forename: Efrat
authors.initials: E
authors.lastname: Monsonego-Ornan
authors.affiliation: Department of Integrative Biology, University of Guelph, 50 Stone Road East, Guelph, Ontario, Canada.
authors.forename: Jim
authors.initials: J
authors.lastname: Ballantyne
authors.affiliation: Department of Biology, Ghent University, Ledeganckstraat 35, 9000 Gent, Belgium.
authors.forename: P Eckhard
authors.initials: PE
authors.lastname: Witten
authors.affiliation: Laboratoire de Paléontologie et Biologie Évolutive, Université du Québec à Rimouski, 300 Allée des Ursulines, Rimouski, QC G5L 3A1, Canada.
authors.forename: Cyrena
authors.initials: C
authors.lastname: Riley
authors.affiliation: Department Biomaterials, Max Planck Institute of Colloids & Interfaces, Am Muehlenberg 1, 14424 Potsdam, Germany.
authors.forename: Wouter
authors.initials: W
authors.lastname: Habraken
authors.affiliation: Department of Chemical and Biological Engineering, University of Ottawa, Colonel By Building, 161 Louis Pasteur Pvt., Room A-408, Ottawa K1N 6N5, Canada.
authors.forename: Sidney
authors.initials: S
authors.lastname: Omelon
mesh_terms: D000818:Animals; D001639:Bicarbonates / Q000378:metabolism; D002118:Calcium / Q000378:metabolism; D002356:Cartilage / Q000378:metabolism*; D018940:Elasmobranchii / Q000145:classification / Q000378:metabolism*; D006706:Homeostasis; D008903:Minerals / Q000378:metabolism*; D010710:Phosphates / Q000378:metabolism; D012754:Sharks / Q000378:metabolism*; D012860:Skates, Fish / Q000378:metabolism*
chemical_list: D001639:Bicarbonates; D008903:Minerals; D010710:Phosphates; D002118:Calcium
keywords: Apatite; Biomineralization; Elasmobranch; Skeleton; Tessellated cartilage; Tesserae