title: Spicule formation in calcareous sponges: Coordinated expression of biomineralization genes and spicule-type specific genes.
abstract: The ability to form mineral structures under biological control is widespread among animals. In several species, specific proteins have been shown to be involved in biomineralization, but it is uncertain how they influence the shape of the growing biomineral and the resulting skeleton. Calcareous sponges are the only sponges that form calcitic spicules, which, based on the number of rays (actines) are distinguished in diactines, triactines and tetractines. Each actine is formed by only two cells, called sclerocytes. Little is known about biomineralization proteins in calcareous sponges, other than that specific carbonic anhydrases (CAs) have been identified, and that uncharacterized Asx-rich proteins have been isolated from calcitic spicules. By RNA-Seq and RNA in situ hybridization (ISH), we identified five additional biomineralization genes in Sycon ciliatum: two bicarbonate transporters (BCTs) and three Asx-rich extracellular matrix proteins (ARPs). We show that these biomineralization genes are expressed in a coordinated pattern during spicule formation. Furthermore, two of the ARPs are spicule-type specific for triactines and tetractines (ARP1 or SciTriactinin) or diactines (ARP2 or SciDiactinin). Our results suggest that spicule formation is controlled by defined temporal and spatial expression of spicule-type specific sets of biomineralization genes.
authors.affiliation: Department of Earth and Environmental Sciences, Palaeontology and Geobiology, Ludwig-Maximilians-Universität München, Richard-Wagner-Str. 10, 80333 Munich, Germany.
authors.forename: Oliver
authors.initials: O
authors.lastname: Voigt
authors.affiliation: Research School of Biology, ANU College of Medicine, Biology and Environment, The Australian National University, Canberra, 46 Sullivans Creek Road, Acton ACT 2601, Australia.
authors.forename: Maja
authors.initials: M
authors.lastname: Adamska
authors.affiliation: Research School of Biology, ANU College of Medicine, Biology and Environment, The Australian National University, Canberra, 46 Sullivans Creek Road, Acton ACT 2601, Australia.
authors.forename: Marcin
authors.initials: M
authors.lastname: Adamski
authors.affiliation: Department of Earth and Environmental Sciences, Palaeontology and Geobiology, Ludwig-Maximilians-Universität München, Richard-Wagner-Str. 10, 80333 Munich, Germany.
authors.forename: André
authors.initials: A
authors.lastname: Kittelmann
authors.affiliation: Department of Earth and Environmental Sciences, Palaeontology and Geobiology, Ludwig-Maximilians-Universität München, Richard-Wagner-Str. 10, 80333 Munich, Germany.
authors.forename: Lukardis
authors.initials: L
authors.lastname: Wencker
authors.affiliation: Department of Earth and Environmental Sciences, Palaeontology and Geobiology, Ludwig-Maximilians-Universität München, Richard-Wagner-Str. 10, 80333 Munich, Germany.|GeoBio-Center, Ludwig-Maximilians-Universität München, Richard-Wagner-Str. 10, 80333 München, Germany.|Bayerische Staatssammlung für Paläontologie und Geologie, Richard-Wagner-Str. 10, 80333 München, Germany.
authors.forename: Gert
authors.initials: G
authors.lastname: Wörheide
mesh_terms: D000825:Animal Structures / Q000378:metabolism*; D000818:Animals; D027321:Anion Transport Proteins / Q000378:metabolism; D001639:Bicarbonates / Q000378:metabolism; D016326:Extracellular Matrix Proteins / Q000235:genetics; D020869:Gene Expression Profiling; D017403:In Situ Hybridization; D011161:Porifera / Q000235:genetics / Q000378:metabolism*; D017423:Sequence Analysis, RNA
chemical_list: D027321:Anion Transport Proteins; D001639:Bicarbonates; D016326:Extracellular Matrix Proteins