title: Localization and characterization of ferritin in Demospongiae: a possible role on spiculogenesis.
abstract: Iron, as inorganic ion or as oxide, is widely used by biological systems in a myriad of biological functions (e.g., enzymatic, gene activation and/or regulation). In particular, marine organisms containing silica structures--diatoms and sponges--grow preferentially in the presence of iron. Using primary sponge cell culture from S. domuncula-primmorphs--as an in vitro model to study the Demospongiae spiculogenesis, we found the presence of agglomerates 50 nm in diameter exclusively inside sponge specialized cells called sclerocytes. A clear phase/material separation is observed between the agglomerates and the initial stages of intracellular spicule formation. STEM-HRTEM-EDX analysis of the agglomerates (30-100 nm) showed that they are composed of pseudohexagonal nanoparticles between 5 and 15 nm in size, displaying lattice parameters corresponding to hematite (Fe2O3) and mixed iron oxide phases typically attributed to ferritin. Further analysis, using western blotting, inductively coupled plasma mass spectrometry (ICP-MS), sequence alignment analysis, immunostaining and magnetic resonance imaging (MRI), of mature spicule filaments confirm the presence of ferritin within these organic structures. We suggest that S. domuncula can be classified as a dual biomineralizating organism, i.e., within the same cellular structure two distinct biomineralizing processes can occur as a result of the same cellular/metabolic function, spiculogenesis.
authors.affiliation: Institut für Chemie-Anorganische Chemie, Naturwissenschaftliche Fakultät II-Chemie, Physik und Mathematik, Martin-Luther-Universität Halle-Wittenberg, Kurt-Mothes-Straße 2, Halle 06120, Germany. filipe.natalio@chemie.uni-halle.de.
authors.forename: Filipe
authors.initials: F
authors.lastname: Natalio
authors.affiliation: Institut für Chemie-Anorganische Chemie, Naturwissenschaftliche Fakultät II-Chemie, Physik und Mathematik, Martin-Luther-Universität Halle-Wittenberg, Kurt-Mothes-Straße 2, Halle 06120, Germany. stefanie.wiese@chemie.uni-halle.de.
authors.forename: Stefanie
authors.initials: S
authors.lastname: Wiese
authors.affiliation: Institut für Chemie-Anorganische Chemie, Naturwissenschaftliche Fakultät II-Chemie, Physik und Mathematik, Martin-Luther-Universität Halle-Wittenberg, Kurt-Mothes-Straße 2, Halle 06120, Germany. norman.friedrich@chemie.uni-halle.de.
authors.forename: Norman
authors.initials: N
authors.lastname: Friedrich
authors.affiliation: Max-Planck Institute of Microstructure Physics, Weinberg 2, Halle 06120, Germany. werner@mpi-halle.mpg.de.
authors.forename: Peter
authors.initials: P
authors.lastname: Werner
authors.affiliation: Institut für Anorganische Chemie und Analytische Chemie, Johannes Gutenberg-Universität, Duesbergweg 10-14, Mainz 55099, Germany. tahir@uni-mainz.de.
authors.forename: Muhammad Nawaz
authors.initials: MN
authors.lastname: Tahir
mesh_terms: D000818:Animals; D002478:Cells, Cultured; D017377:Diatoms / Q000378:metabolism; D005290:Ferric Compounds / Q000378:metabolism; D005293:Ferritins / Q000378:metabolism*; D007501:Iron / Q000378:metabolism; D011161:Porifera / Q000378:metabolism*; D012822:Silicon Dioxide / Q000378:metabolism; D047233:Suberites / Q000378:metabolism
chemical_list: D005290:Ferric Compounds; C000499:ferric oxide; D012822:Silicon Dioxide; D005293:Ferritins; D007501:Iron