title: Biomineral ultrastructure, elemental constitution and genomic analysis of biomineralization-related proteins in hemichordates.
abstract: Here, we report the discovery and characterization of biominerals in the acorn worms Saccoglossus bromophenolosus and Ptychodera flava galapagos (Phylum: Hemichordata). Using electron microscopy, X-ray microprobe analyses and confocal Raman spectroscopy, we show that hemichordate biominerals are small CaCO(3) aragonitic elements restricted to specialized epidermal structures, and in S. bromophenolosus, are apparently secreted by sclerocytes. Investigation of urchin biomineralizing proteins in the translated genome and expressed sequence tag (EST) libraries of Saccoglossus kowalevskii indicates that three members of the urchin MSP-130 family, a carbonic anhydrase and a matrix metaloprotease are present and transcribed during the development of S. kowalevskii. The SM family of proteins is absent from the hemichordate genome. These results increase the number of phyla known to biomineralize and suggest that some of the gene-regulatory 'toolkit', if not mineralized tissue themselves, may have been present in the common ancestor to hemichordates and echinoderms.
authors.affiliation: Département de Sciences Biologiques, Université de Montréal, C.P. 6128, Succ. Centre-ville, Montréal, Quebec, Canada, H3C 3J7. c.cameron@umontreal.ca
authors.forename: C B
authors.initials: CB
authors.lastname: Cameron
authors.forename: C D
authors.initials: CD
authors.lastname: Bishop
mesh_terms: D000818:Animals; D002113:Calcification, Physiologic; D002119:Calcium Carbonate / Q000737:chemistry*; D002256:Carbonic Anhydrases / Q000737:chemistry / Q000235:genetics; D002816:Chordata, Nonvertebrate / Q000235:genetics* / Q000378:metabolism / Q000648:ultrastructure*; D016678:Genome; D023281:Genomics; D053509:Matrix Metalloproteinase 13 / Q000737:chemistry / Q000235:genetics; D017348:Microscopy, Electron, Scanning Transmission; D011506:Proteins / Q000737:chemistry* / Q000235:genetics; D013059:Spectrum Analysis, Raman
chemical_list: D011506:Proteins; D053509:Matrix Metalloproteinase 13; D002256:Carbonic Anhydrases; D002119:Calcium Carbonate