title: Otoc1: a novel otoconin-90 ortholog required for otolith mineralization in zebrafish.
abstract: Within the vestibular system of virtually all vertebrate species, gravity and linear acceleration are detected via coupling of calcified masses to the cilia of mechanosensory hair cells. The mammalian ear contains thousands of minute biomineralized particles called otoconia, whereas the inner ear of teleost fish contains three large ear stones called otoliths that serve a similar function. Otoconia and otoliths are composed of calcium carbonate crystals condensed on a core protein lattice. Otoconin-90 (Oc90) is the major matrix protein of mammalian and avian otoconia, while otolith matrix protein (OMP) is the most abundant matrix protein found in the otoliths of teleost fish. We have identified a novel gene, otoc1, which encodes the zebrafish ortholog of Oc90. Expression of otoc1 was detected in the ear between 15 hpf and 72 hpf, and was restricted primarily to the macula and the developing epithelial pillars of the semicircular canals. Expression of otoc1 was also detected in epiphysis, optic stalk, midbrain, diencephalon, flexural organ, and spinal cord. During embryogenesis, expression of otoc1 mRNA preceded the appearance of omp-1 transcripts. Knockdown of otoc1 mRNA translation with antisense morpholinos produced a variety of aberrant otolith phenotypes. Our results suggest that Otoc1 may serve to nucleate calcium carbonate mineralization of aragonitic otoliths.
authors.affiliation: Department of Pharmacology, Penn State University College of Medicine, Hershey, PA 17033, USA.
authors.forename: Jessica A
authors.initials: JA
authors.lastname: Petko
authors.forename: Bonny B
authors.initials: BB
authors.lastname: Millimaki
authors.forename: Victor A
authors.initials: VA
authors.lastname: Canfield
authors.forename: Bruce B
authors.initials: BB
authors.lastname: Riley
authors.forename: Robert
authors.initials: R
authors.lastname: Levenson
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D001921:Brain / Q000166:cytology / Q000196:embryology / Q000378:metabolism; D002119:Calcium Carbonate / Q000378:metabolism; D002135:Calcium-Binding Proteins; D015536:Down-Regulation / Q000235:genetics; D016326:Extracellular Matrix Proteins / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D018507:Gene Expression Regulation, Developmental / Q000235:genetics; D008903:Minerals / Q000378:metabolism; D008969:Molecular Sequence Data; D010037:Otolithic Membrane / Q000166:cytology / Q000196:embryology* / Q000378:metabolism; D010802:Phylogeny; D014176:Protein Biosynthesis / Q000235:genetics; D016372:RNA, Antisense / Q000494:pharmacology; D012333:RNA, Messenger / Q000032:analysis / Q000235:genetics / Q000378:metabolism; D012665:Semicircular Canals / Q000166:cytology / Q000196:embryology / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D012689:Sequence Homology, Nucleic Acid; D014722:Vestibule, Labyrinth / Q000166:cytology / Q000196:embryology* / Q000378:metabolism; D015027:Zebrafish / Q000196:embryology* / Q000235:genetics / Q000378:metabolism; D029961:Zebrafish Proteins / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*
chemical_list: D002135:Calcium-Binding Proteins; D016326:Extracellular Matrix Proteins; D008903:Minerals; C512837:Oc90 protein, mouse; C528118:Oc90 protein, zebrafish; D016372:RNA, Antisense; D012333:RNA, Messenger; D029961:Zebrafish Proteins; D002119:Calcium Carbonate