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Sheets L, Holmgren M, Kindt KS. How Zebrafish Can Drive the Future of Genetic-based Hearing and Balance Research. J Assoc Res Otolaryngol 2021; 22:215-235. [PMID: 33909162 PMCID: PMC8110678 DOI: 10.1007/s10162-021-00798-z] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2020] [Accepted: 03/23/2021] [Indexed: 02/06/2023] Open
Abstract
Over the last several decades, studies in humans and animal models have successfully identified numerous molecules required for hearing and balance. Many of these studies relied on unbiased forward genetic screens based on behavior or morphology to identify these molecules. Alongside forward genetic screens, reverse genetics has further driven the exploration of candidate molecules. This review provides an overview of the genetic studies that have established zebrafish as a genetic model for hearing and balance research. Further, we discuss how the unique advantages of zebrafish can be leveraged in future genetic studies. We explore strategies to design novel forward genetic screens based on morphological alterations using transgenic lines or behavioral changes following mechanical or acoustic damage. We also outline how recent advances in CRISPR-Cas9 can be applied to perform reverse genetic screens to validate large sequencing datasets. Overall, this review describes how future genetic studies in zebrafish can continue to advance our understanding of inherited and acquired hearing and balance disorders.
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Affiliation(s)
- Lavinia Sheets
- Department of Otolaryngology-Head & Neck Surgery, Washington University School of Medicine, St. Louis, MO, USA
| | - Melanie Holmgren
- Department of Otolaryngology-Head & Neck Surgery, Washington University School of Medicine, St. Louis, MO, USA
| | - Katie S Kindt
- Section On Sensory Cell Development and Function, National Institutes On Deafness and Other Communication Disorders, National Institutes of Health, Bethesda, USA.
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2
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Parkinson L, Stawicki TM. alms1 mutant zebrafish do not show hair cell phenotypes seen in other cilia mutants. PLoS One 2021; 16:e0246844. [PMID: 33793549 PMCID: PMC8016283 DOI: 10.1371/journal.pone.0246844] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2020] [Accepted: 01/26/2021] [Indexed: 11/18/2022] Open
Abstract
Multiple cilia-associated genes have been shown to affect hair cells in zebrafish (Danio rerio), including the human deafness gene dcdc2, the radial spoke gene rsph9, and multiple intraflagellar transport (IFT) and transition zone genes. Recently a zebrafish alms1 mutant was generated. The ALMS1 gene is the gene mutated in the ciliopathy Alström Syndrome a disease that causes hearing loss among other symptoms. The hearing loss seen in Alström Syndrome may be due in part to hair cell defects as Alms1 mutant mice show stereocilia polarity defects and a loss of hair cells. Hair cell loss is also seen in postmortem analysis of Alström patients. The zebrafish alms1 mutant has metabolic defects similar to those seen in Alström syndrome and Alms1 mutant mice. We wished to investigate if it also had hair cell defects. We, however, failed to find any hair cell related phenotypes in alms1 mutant zebrafish. They had normal lateral line hair cell numbers as both larvae and adults and normal kinocilia formation. They also showed grossly normal swimming behavior, response to vibrational stimuli, and FM1-43 loading. Mutants also showed a normal degree of sensitivity to both short-term neomycin and long-term gentamicin treatment. These results indicate that cilia-associated genes differentially affect different hair cell types.
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Affiliation(s)
- Lauren Parkinson
- Neuroscience Program, Lafayette College, Easton, Pennsylvania, United States of America
| | - Tamara M. Stawicki
- Neuroscience Program, Lafayette College, Easton, Pennsylvania, United States of America
- * E-mail:
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3
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Vona B, Doll J, Hofrichter MAH, Haaf T, Varshney GK. Small fish, big prospects: using zebrafish to unravel the mechanisms of hereditary hearing loss. Hear Res 2020; 397:107906. [PMID: 32063424 PMCID: PMC7415493 DOI: 10.1016/j.heares.2020.107906] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/08/2019] [Revised: 01/13/2020] [Accepted: 01/29/2020] [Indexed: 12/16/2022]
Abstract
Over the past decade, advancements in high-throughput sequencing have greatly enhanced our knowledge of the mutational signatures responsible for hereditary hearing loss. In its present state, the field has a largely uncensored view of protein coding changes in a growing number of genes that have been associated with hereditary hearing loss, and many more that have been proposed as candidate genes. Sequencing data can now be generated using methods that have become widespread and affordable. The greatest hurdles facing the field concern functional validation of uncharacterized genes and rapid application to human diseases, including hearing and balance disorders. To date, over 30 hearing-related disease models exist in zebrafish. New genome editing technologies, including CRISPR/Cas9 will accelerate the functional validation of hearing loss genes and variants in zebrafish. Here, we discuss current progress in the field and recent advances in genome editing approaches.
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Affiliation(s)
- Barbara Vona
- Department of Otolaryngology--Head & Neck Surgery, Tübingen Hearing Research Centre, Eberhard Karls University Tübingen, Tübingen, Germany.
| | - Julia Doll
- Institute of Human Genetics, Julius Maximilians University, Würzburg, Germany
| | | | - Thomas Haaf
- Institute of Human Genetics, Julius Maximilians University, Würzburg, Germany
| | - Gaurav K Varshney
- Genes & Human Disease Research Program, Oklahoma Medical Research Foundation, Oklahoma City, OK, United States.
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4
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Bremer J, Marsden KC, Miller A, Granato M. The ubiquitin ligase PHR promotes directional regrowth of spinal zebrafish axons. Commun Biol 2019; 2:195. [PMID: 31149640 PMCID: PMC6531543 DOI: 10.1038/s42003-019-0434-2] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2019] [Accepted: 04/16/2019] [Indexed: 01/05/2023] Open
Abstract
To reconnect with their synaptic targets, severed axons need to regrow robustly and directionally along the pre-lesional trajectory. While mechanisms directing axonal regrowth are poorly understood, several proteins direct developmental axon outgrowth, including the ubiquitin ligase PHR (Mycbp2). Invertebrate PHR also limits regrowth of injured axons, whereas its role in vertebrate axonal regrowth remains elusive. Here we took advantage of the high regrowth capacity of spinal zebrafish axons and observed robust and directional regrowth following laser transection of spinal Mauthner axons. We found that PHR directs regrowing axons along the pre-lesional trajectory and across the transection site. At the transection site, initial regrowth of wild-type axons was multidirectional. Over time, misdirected sprouts were corrected in a PHR-dependent manner. Ablation of cyfip2, known to promote F-actin-polymerization and pharmacological inhibition of JNK reduced misdirected regrowth of PHR-deficient axons, suggesting that PHR controls directional Mauthner axonal regrowth through cyfip2- and JNK-dependent pathways.
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Affiliation(s)
- Juliane Bremer
- Department of Cell and Developmental Biology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, 19104 PA USA
| | - Kurt C. Marsden
- Department of Cell and Developmental Biology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, 19104 PA USA
- Present Address: Department of Biological Sciences, North Carolina State University, Raleigh, 27607 NC USA
| | - Adam Miller
- Institute of Neuroscience, University of Oregon, Eugene, 97405 OR USA
| | - Michael Granato
- Department of Cell and Developmental Biology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, 19104 PA USA
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5
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Johnson CA. Obituary: Jarema Malicki (1965-2019). Development 2019. [DOI: 10.1242/dev.176677] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
ABSTRACT
Jarema Malicki, a pioneer in developmental studies of the vertebrate retina, died on 4th January 2019, shortly after being diagnosed with cancer. Here, I reflect on Jarema's life and work, with a particular focus on his research interests in zebrafish as a model organism for vertebrate retinogenesis and human ciliopathies.
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Affiliation(s)
- Colin A. Johnson
- Leeds Institute of Medical Research, The University of Leeds, Wellcome Trust Brenner Building, Beckett Street, Leeds LS9 7TF, UK
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6
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Swinburne IA, Mosaliganti KR, Upadhyayula S, Liu TL, Hildebrand DGC, Tsai TYC, Chen A, Al-Obeidi E, Fass AK, Malhotra S, Engert F, Lichtman JW, Kirchhausen T, Betzig E, Megason SG. Lamellar projections in the endolymphatic sac act as a relief valve to regulate inner ear pressure. eLife 2018; 7:37131. [PMID: 29916365 PMCID: PMC6008045 DOI: 10.7554/elife.37131] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2018] [Accepted: 05/09/2018] [Indexed: 01/23/2023] Open
Abstract
The inner ear is a fluid-filled closed-epithelial structure whose function requires maintenance of an internal hydrostatic pressure and fluid composition. The endolymphatic sac (ES) is a dead-end epithelial tube connected to the inner ear whose function is unclear. ES defects can cause distended ear tissue, a pathology often seen in hearing and balance disorders. Using live imaging of zebrafish larvae, we reveal that the ES undergoes cycles of slow pressure-driven inflation followed by rapid deflation. Absence of these cycles in lmx1bb mutants leads to distended ear tissue. Using serial-section electron microscopy and adaptive optics lattice light-sheet microscopy, we find a pressure relief valve in the ES comprised of partially separated apical junctions and dynamic overlapping basal lamellae that separate under pressure to release fluid. We propose that this lmx1-dependent pressure relief valve is required to maintain fluid homeostasis in the inner ear and other fluid-filled cavities. The most internal part of the human ear, the inner ear, is essential for us to hear and have a sense of balance. It is formed by a complex series of connected cavities filled by a liquid. When sound waves and changes in the position of the body make this liquid move, specialized ‘hair’ cells can detect these subtle movements; neurons then relay this information to the brain where it is decoded and interpreted. For the inner ear to work properly, the body needs to finely regulate the pressure created by the liquid inside the cavities. For example, people with unstable pressure in their ears can experience deafness or problems with balance. A structure known as the endolymphatic sac, which is a balloon-like chamber connected to the rest of the inner ear by a thin tube, helps with this regulation. However, scientists are still unsure about how exactly the sac performs its role. One problem is that the inner ear is difficult to study because it is encased in one of the densest bones in the body. Many other animals also have inner ears, from fish to birds and mammals. Here, Swinburne et al. examine the inner ear of zebrafish embryos because, in this fish, the ear starts working before the bones around it form; the structure is therefore accessible for injections and microscopy. Experiments show that when the pressure in the inner ear rises, the endolymphatic sac slowly fills up with the ear liquid, and then it rapidly deflates. Fish with mutations that stop the sac from deflating have overinflated sacs, which is a symptom also found in certain patients with hearing and balance disorders. Looking into the details of these inflation-deflation cycles, Swinburne et al. found that the cells that form the sac have gaps between them, unlike a normal sheet of cells. A flap covers these gaps to keep the liquid in, but under pressure, the flap opens and the liquid can escape. These results show that the endolymphatic sac works as a pressure relief valve for the inner ear. Ultimately, understanding how pressure is regulated in the ear could help patients with inner ear disorders. It could also serve as a template to investigate how eyes, kidneys and the brain, which all have liquid-filled cavities, control their internal pressure.
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Affiliation(s)
- Ian A Swinburne
- Department of Systems Biology, Harvard Medical School, Boston, United States
| | | | - Srigokul Upadhyayula
- Department of Pediatrics, Harvard Medical School, Boston, United States.,Program in Cellular and Molecular Medicine, Boston Children's Hospital, Boston, United States.,Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, United States
| | - Tsung-Li Liu
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, United States
| | - David G C Hildebrand
- Department of Molecular and Cellular Biology, Harvard University, Cambridge, United States
| | - Tony Y-C Tsai
- Department of Systems Biology, Harvard Medical School, Boston, United States
| | - Anzhi Chen
- Department of Systems Biology, Harvard Medical School, Boston, United States
| | - Ebaa Al-Obeidi
- Department of Systems Biology, Harvard Medical School, Boston, United States
| | - Anna K Fass
- Department of Systems Biology, Harvard Medical School, Boston, United States
| | - Samir Malhotra
- Department of Systems Biology, Harvard Medical School, Boston, United States
| | - Florian Engert
- Department of Molecular and Cellular Biology, Harvard University, Cambridge, United States
| | - Jeff W Lichtman
- Department of Molecular and Cellular Biology, Harvard University, Cambridge, United States
| | - Tomas Kirchhausen
- Department of Pediatrics, Harvard Medical School, Boston, United States.,Program in Cellular and Molecular Medicine, Boston Children's Hospital, Boston, United States.,Department of Cell Biology, Harvard Medical School, Boston, United States
| | - Eric Betzig
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, United States
| | - Sean G Megason
- Department of Systems Biology, Harvard Medical School, Boston, United States
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7
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Nagao Y, Takada H, Miyadai M, Adachi T, Seki R, Kamei Y, Hara I, Taniguchi Y, Naruse K, Hibi M, Kelsh RN, Hashimoto H. Distinct interactions of Sox5 and Sox10 in fate specification of pigment cells in medaka and zebrafish. PLoS Genet 2018; 14:e1007260. [PMID: 29621239 PMCID: PMC5886393 DOI: 10.1371/journal.pgen.1007260] [Citation(s) in RCA: 42] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2017] [Accepted: 02/15/2018] [Indexed: 01/06/2023] Open
Abstract
Mechanisms generating diverse cell types from multipotent progenitors are fundamental for normal development. Pigment cells are derived from multipotent neural crest cells and their diversity in teleosts provides an excellent model for studying mechanisms controlling fate specification of distinct cell types. Zebrafish have three types of pigment cells (melanocytes, iridophores and xanthophores) while medaka have four (three shared with zebrafish, plus leucophores), raising questions about how conserved mechanisms of fate specification of each pigment cell type are in these fish. We have previously shown that the Sry-related transcription factor Sox10 is crucial for fate specification of pigment cells in zebrafish, and that Sox5 promotes xanthophores and represses leucophores in a shared xanthophore/leucophore progenitor in medaka. Employing TILLING, TALEN and CRISPR/Cas9 technologies, we generated medaka and zebrafish sox5 and sox10 mutants and conducted comparative analyses of their compound mutant phenotypes. We show that specification of all pigment cells, except leucophores, is dependent on Sox10. Loss of Sox5 in Sox10-defective fish partially rescued the formation of all pigment cells in zebrafish, and melanocytes and iridophores in medaka, suggesting that Sox5 represses Sox10-dependent formation of these pigment cells, similar to their interaction in mammalian melanocyte specification. In contrast, in medaka, loss of Sox10 acts cooperatively with Sox5, enhancing both xanthophore reduction and leucophore increase in sox5 mutants. Misexpression of Sox5 in the xanthophore/leucophore progenitors increased xanthophores and reduced leucophores in medaka. Thus, the mode of Sox5 function in xanthophore specification differs between medaka (promoting) and zebrafish (repressing), which is also the case in adult fish. Our findings reveal surprising diversity in even the mode of the interactions between Sox5 and Sox10 governing specification of pigment cell types in medaka and zebrafish, and suggest that this is related to the evolution of a fourth pigment cell type. How individual cell fates become specified from multipotent progenitors is a fundamental question in developmental and stem cell biology. Body pigment cells derive from a multipotent progenitor, but while in zebrafish there are three types of pigment cells (melanocytes, iridophores and xanthophores), in medaka these progenitors form four (as zebrafish, plus leucophores). Here, we address whether mechanisms generating each cell-type are conserved between the two species. We focus on two key regulatory proteins, Sox5 and Sox10, which we previously showed were involved in pigment cell development in medaka and zebrafish, respectively. We compare experimentally how the two proteins interact in regulating development of each of the pigment cell lineages in these fish. We show that development of all pigment cells, except leucophores, is dependent on Sox10, and that Sox5 modulates Sox10 activity antagonistically in all pigment cells in zebrafish, and melanocytes and iridophores in medaka. Surprisingly, in medaka, Sox5 acts co-operatively with Sox10 to promote xanthophore fate and to repress leucophore fate. Our findings reveal surprising diversity how Sox5 and Sox10 interact to govern pigment cell development in medaka and zebrafish, and suggest that this likely relates to the evolution of the novel leucophore pigment cell type in medaka.
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Affiliation(s)
- Yusuke Nagao
- Bioscience and Biotechnology Center and Division of Biological Science, Graduate School of Science, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, Aichi, Japan
- Department of Biology and Biochemistry, University of Bath, Claverton Down, Bath, United Kingdom
| | - Hiroyuki Takada
- Bioscience and Biotechnology Center and Division of Biological Science, Graduate School of Science, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, Aichi, Japan
| | - Motohiro Miyadai
- Bioscience and Biotechnology Center and Division of Biological Science, Graduate School of Science, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, Aichi, Japan
| | - Tomoko Adachi
- Bioscience and Biotechnology Center and Division of Biological Science, Graduate School of Science, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, Aichi, Japan
| | - Ryoko Seki
- Bioscience and Biotechnology Center and Division of Biological Science, Graduate School of Science, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, Aichi, Japan
| | - Yasuhiro Kamei
- Department of Basic Biology, School of Life Science, Graduate University of Advanced Studies (SOKENDAI), Myodaiji, Okazaki, Aichi, Japan
- Spectrography and Bioimaging Facility, National Institute for Basic Biology, Myodaiji, Okazaki, Aichi, Japan
| | - Ikuyo Hara
- Department of Basic Biology, School of Life Science, Graduate University of Advanced Studies (SOKENDAI), Myodaiji, Okazaki, Aichi, Japan
- Laboratory of Bioresources, National Institute for Basic Biology, Myodaiji, Okazaki, Aichi, Japan
| | - Yoshihito Taniguchi
- Department of Public Health and Preventive Medicine, Kyorin University, School of Medicine, Mitaka, Tokyo, Japan
| | - Kiyoshi Naruse
- Department of Basic Biology, School of Life Science, Graduate University of Advanced Studies (SOKENDAI), Myodaiji, Okazaki, Aichi, Japan
- Laboratory of Bioresources, National Institute for Basic Biology, Myodaiji, Okazaki, Aichi, Japan
| | - Masahiko Hibi
- Bioscience and Biotechnology Center and Division of Biological Science, Graduate School of Science, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, Aichi, Japan
| | - Robert N. Kelsh
- Department of Biology and Biochemistry, University of Bath, Claverton Down, Bath, United Kingdom
- * E-mail: (HH); (RNK)
| | - Hisashi Hashimoto
- Bioscience and Biotechnology Center and Division of Biological Science, Graduate School of Science, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, Aichi, Japan
- * E-mail: (HH); (RNK)
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8
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Blanco-Sánchez B, Clément A, Phillips JB, Westerfield M. Zebrafish models of human eye and inner ear diseases. Methods Cell Biol 2016; 138:415-467. [PMID: 28129854 DOI: 10.1016/bs.mcb.2016.10.006] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Eye and inner ear diseases are the most common sensory impairments that greatly impact quality of life. Zebrafish have been intensively employed to understand the fundamental mechanisms underlying eye and inner ear development. The zebrafish visual and vestibulo-acoustic systems are very similar to these in humans, and although not yet mature, they are functional by 5days post-fertilization (dpf). In this chapter, we show how the zebrafish has significantly contributed to the field of biomedical research and how researchers, by establishing disease models and meticulously characterizing their phenotypes, have taken the first steps toward therapies. We review here models for (1) eye diseases, (2) ear diseases, and (3) syndromes affecting eye and/or ear. The use of new genome editing technologies and high-throughput screening systems should increase considerably the speed at which knowledge from zebrafish disease models is acquired, opening avenues for better diagnostics, treatments, and therapies.
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Affiliation(s)
| | - A Clément
- University of Oregon, Eugene, OR, United States
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9
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Leventea E, Hazime K, Zhao C, Malicki J. Analysis of cilia structure and function in zebrafish. Methods Cell Biol 2016; 133:179-227. [PMID: 27263414 DOI: 10.1016/bs.mcb.2016.04.016] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Cilia are microtubule-based protrusions on the surface of most eukaryotic cells. They are found in most, if not all, vertebrate organs. Prominent cilia form in sensory structures, the eye, the ear, and the nose, where they are crucial for the detection of environmental stimuli, such as light and odors. Cilia are also involved in developmental processes, including left-right asymmetry formation, limb morphogenesis, and the patterning of neurons in the neural tube. Some cilia, such as those found in nephric ducts, are thought to have mechanosensory roles. Zebrafish proved very useful in genetic analysis and imaging of cilia-related processes, and in the modeling of mechanisms behind human cilia abnormalities, known as ciliopathies. A number of zebrafish defects resemble those seen in human ciliopathies. Forward and reverse genetic strategies generated a wide range of cilia mutants in zebrafish, which can be studied using sophisticated genetic and imaging approaches. In this chapter, we provide a set of protocols to examine cilia morphology, motility, and cilia-related defects in a variety of organs, focusing on the embryo and early postembryonic development.
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Affiliation(s)
- E Leventea
- The University of Sheffield, Sheffield, United Kingdom
| | - K Hazime
- The University of Sheffield, Sheffield, United Kingdom
| | - C Zhao
- The University of Sheffield, Sheffield, United Kingdom; Ocean University of China, Qingdao, China
| | - J Malicki
- The University of Sheffield, Sheffield, United Kingdom
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10
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Smith ME, Monroe JD. Causes and Consequences of Sensory Hair Cell Damage and Recovery in Fishes. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2016; 877:393-417. [PMID: 26515323 DOI: 10.1007/978-3-319-21059-9_17] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/11/2023]
Abstract
Sensory hair cells are the mechanotransductive receptors that detect gravity, sound, and vibration in all vertebrates. Damage to these sensitive receptors often results in deficits in vestibular function and hearing. There are currently two main reasons for studying the process of hair cell loss in fishes. First, fishes, like other non-mammalian vertebrates, have the ability to regenerate hair cells that have been damaged or lost via exposure to ototoxic chemicals or acoustic overstimulation. Thus, they are used as a biomedical model to understand the process of hair cell death and regeneration and find therapeutics that treat or prevent human hearing loss. Secondly, scientists and governmental natural resource managers are concerned about the potential effects of intense anthropogenic sounds on aquatic organisms, including fishes. Dr. Arthur N. Popper and his students, postdocs and research associates have performed pioneering experiments in both of these lines of fish hearing research. This review will discuss the current knowledge regarding the causes and consequences of both lateral line and inner ear hair cell damage in teleost fishes.
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Affiliation(s)
- Michael E Smith
- Department of Biology, Western Kentucky University, Bowling Green, KY, 42101, USA.
| | - J David Monroe
- Department of Biology, Western Kentucky University, Bowling Green, KY, 42101, USA.
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11
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Schulz-Mirbach T, Ladich F. Diversity of Inner Ears in Fishes: Possible Contribution Towards Hearing Improvements and Evolutionary Considerations. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2016; 877:341-91. [DOI: 10.1007/978-3-319-21059-9_16] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/03/2022]
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12
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Nishimura Y, Inoue A, Sasagawa S, Koiwa J, Kawaguchi K, Kawase R, Maruyama T, Kim S, Tanaka T. Using zebrafish in systems toxicology for developmental toxicity testing. Congenit Anom (Kyoto) 2016; 56:18-27. [PMID: 26537640 DOI: 10.1111/cga.12142] [Citation(s) in RCA: 136] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/07/2015] [Accepted: 10/27/2015] [Indexed: 12/20/2022]
Abstract
With the high cost and the long-term assessment of developmental toxicity testing in mammals, the vertebrate zebrafish has become a useful alternative model organism for high-throughput developmental toxicity testing. Zebrafish is also very favorable for the 3R perspective in toxicology; however, the methodologies used by research groups vary greatly, posing considerable challenges to integrative analysis. In this review, we discuss zebrafish developmental toxicity testing, focusing on the methods of chemical exposure, the assessment of morphological abnormalities, housing conditions and their effects on the production of healthy embryos, and future directions. Zebrafish as a systems toxicology model has the potential to elucidate developmental toxicity pathways, and to provide a sound basis for human health risk assessments.
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Affiliation(s)
- Yuhei Nishimura
- Department of Molecular and Cellular Pharmacology, Pharmacogenomics and Pharmacoinformatics, Mie University Graduate School of Medicine, Tsu, Mie.,Mie University Medical Zebrafish Research Center, Tsu, Mie.,Department of Systems Pharmacology, Mie University Graduate School of Medicine, Tsu, Mie.,Department of Omics Medicine, Mie University Industrial Technology Innovation Institute, Tsu, Mie.,Department of Bioinformatics, Mie University Life Science Research Center, Tsu, Mie
| | | | - Shota Sasagawa
- Department of Molecular and Cellular Pharmacology, Pharmacogenomics and Pharmacoinformatics, Mie University Graduate School of Medicine, Tsu, Mie
| | - Junko Koiwa
- Department of Molecular and Cellular Pharmacology, Pharmacogenomics and Pharmacoinformatics, Mie University Graduate School of Medicine, Tsu, Mie
| | - Koki Kawaguchi
- Department of Molecular and Cellular Pharmacology, Pharmacogenomics and Pharmacoinformatics, Mie University Graduate School of Medicine, Tsu, Mie
| | - Reiko Kawase
- Department of Molecular and Cellular Pharmacology, Pharmacogenomics and Pharmacoinformatics, Mie University Graduate School of Medicine, Tsu, Mie
| | | | - Soonih Kim
- Ono Pharmaceutical Co, Ltd, Osaka, Japan
| | - Toshio Tanaka
- Department of Molecular and Cellular Pharmacology, Pharmacogenomics and Pharmacoinformatics, Mie University Graduate School of Medicine, Tsu, Mie.,Mie University Medical Zebrafish Research Center, Tsu, Mie.,Department of Systems Pharmacology, Mie University Graduate School of Medicine, Tsu, Mie.,Department of Omics Medicine, Mie University Industrial Technology Innovation Institute, Tsu, Mie.,Department of Bioinformatics, Mie University Life Science Research Center, Tsu, Mie
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13
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Lin SY, Vollrath MA, Mangosing S, Shen J, Cardenas E, Corey DP. The zebrafish pinball wizard gene encodes WRB, a tail-anchored-protein receptor essential for inner-ear hair cells and retinal photoreceptors. J Physiol 2015; 594:895-914. [PMID: 26593130 DOI: 10.1113/jp271437] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2015] [Accepted: 11/17/2015] [Indexed: 11/08/2022] Open
Abstract
KEY POINTS The zebrafish pinball wizard (pwi) mutant is deaf and blind. The pwi phenotype includes a reduced auditory startle response and reduced visual evoked potentials, suggesting fatigue of synaptic release at ribbon synapses in hair cells and photoreceptors. The gene defective in the pwi mutant is WRB, a protein homologous to the yeast protein Get1, which is involved in the insertion of 'tail-anchored' membrane proteins. Many tail-anchored proteins are associated with synaptic vesicles, and both vesicles and synaptic ribbons are reduced in synaptic regions of hair cells in pwi. Abnormal processing of synaptic vesicle proteins important for ribbon synapses can explain the pwi phenotype. ABSTRACT In a large-scale zebrafish insertional mutagenesis screen, we identified the pinball wizard (pwi) line, which displays a deafness and blindness phenotype. Although the gross morphology and structure of the pwi larval inner ear was near normal, acoustic startle stimuli evoked smaller postsynaptic responses in afferent neurons, which rapidly fatigued. In the retina, similarly, an abnormal electroretinogram suggested reduced transmission at the photoreceptor ribbon synapse. A functional deficit in these specialized synapses was further supported by a reduction of synaptic marker proteins Rab3 and cysteine-string protein (CSP/Dnajc5) in hair cells and photoreceptors, as well as by a reduction of the number of both ribbons and vesicles surrounding the ribbons in hair cells. The pwi gene encodes a homologue of the yeast Get1 and human tryptophan-rich basic (WRB) proteins, which are receptors for membrane insertion of tail-anchored (TA) proteins. We identified more than 100 TA proteins expressed in hair cells, including many synaptic proteins. The expression of synaptobrevin and syntaxin 3, TA proteins essential for vesicle fusion, was reduced in the synaptic layers of mutant retina, consistent with a role for the pwi/WRB protein in TA-protein processing. The WRB protein was located near the apical domain and the ribbons in hair cells, and in the inner segment and the axon of the photoreceptor, consistent with a role in vesicle biogenesis or trafficking. Taken together, our results suggest that WRB plays a critical role in synaptic functions in these two sensory cells, and that disrupted processing of synaptic vesicle TA proteins explains much of the mutant phenotype.
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Affiliation(s)
- Shuh-Yow Lin
- Department of Surgery, UC San Diego School of Medicine, La Jolla, CA, USA
| | - Melissa A Vollrath
- Department of Neurobiology, Harvard Medical School, Boston, MA, USA.,Howard Hughes Medical Institute, Chevy Chase, MD, USA
| | - Sara Mangosing
- Department of Surgery, UC San Diego School of Medicine, La Jolla, CA, USA
| | - Jun Shen
- Department of Neurobiology, Harvard Medical School, Boston, MA, USA.,Howard Hughes Medical Institute, Chevy Chase, MD, USA
| | - Elena Cardenas
- Department of Surgery, UC San Diego School of Medicine, La Jolla, CA, USA
| | - David P Corey
- Department of Neurobiology, Harvard Medical School, Boston, MA, USA.,Howard Hughes Medical Institute, Chevy Chase, MD, USA
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14
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Mitotic cell rounding and epithelial thinning regulate lumen growth and shape. Nat Commun 2015; 6:7355. [PMID: 26077034 DOI: 10.1038/ncomms8355] [Citation(s) in RCA: 57] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2014] [Accepted: 04/29/2015] [Indexed: 01/09/2023] Open
Abstract
Many organ functions rely on epithelial cavities with particular shapes. Morphogenetic anomalies in these cavities lead to kidney, brain or inner ear diseases. Despite their relevance, the mechanisms regulating lumen dimensions are poorly understood. Here, we perform live imaging of zebrafish inner ear development and quantitatively analyse the dynamics of lumen growth in 3D. Using genetic, chemical and mechanical interferences, we identify two new morphogenetic mechanisms underlying anisotropic lumen growth. The first mechanism involves thinning of the epithelium as the cells change their shape and lose fluids in concert with expansion of the cavity, suggesting an intra-organ fluid redistribution process. In the second mechanism, revealed by laser microsurgery experiments, mitotic rounding cells apicobasally contract the epithelium and mechanically contribute to expansion of the lumen. Since these mechanisms are axis specific, they not only regulate lumen growth but also the shape of the cavity.
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15
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Aceto J, Nourizadeh-Lillabadi R, Marée R, Dardenne N, Jeanray N, Wehenkel L, Aleström P, van Loon JJWA, Muller M. Zebrafish Bone and General Physiology Are Differently Affected by Hormones or Changes in Gravity. PLoS One 2015; 10:e0126928. [PMID: 26061167 PMCID: PMC4465622 DOI: 10.1371/journal.pone.0126928] [Citation(s) in RCA: 57] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2014] [Accepted: 04/09/2015] [Indexed: 11/18/2022] Open
Abstract
Teleost fish such as zebrafish (Danio rerio) are increasingly used for physiological, genetic and developmental studies. Our understanding of the physiological consequences of altered gravity in an entire organism is still incomplete. We used altered gravity and drug treatment experiments to evaluate their effects specifically on bone formation and more generally on whole genome gene expression. By combining morphometric tools with an objective scoring system for the state of development for each element in the head skeleton and specific gene expression analysis, we confirmed and characterized in detail the decrease or increase of bone formation caused by a 5 day treatment (from 5dpf to 10 dpf) of, respectively parathyroid hormone (PTH) or vitamin D3 (VitD3). Microarray transcriptome analysis after 24 hours treatment reveals a general effect on physiology upon VitD3 treatment, while PTH causes more specifically developmental effects. Hypergravity (3g from 5dpf to 9 dpf) exposure results in a significantly larger head and a significant increase in bone formation for a subset of the cranial bones. Gene expression analysis after 24 hrs at 3g revealed differential expression of genes involved in the development and function of the skeletal, muscular, nervous, endocrine and cardiovascular systems. Finally, we propose a novel type of experimental approach, the "Reduced Gravity Paradigm", by keeping the developing larvae at 3g hypergravity for the first 5 days before returning them to 1g for one additional day. 5 days exposure to 3g during these early stages also caused increased bone formation, while gene expression analysis revealed a central network of regulatory genes (hes5, sox10, lgals3bp, egr1, edn1, fos, fosb, klf2, gadd45ba and socs3a) whose expression was consistently affected by the transition from hyper- to normal gravity.
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Affiliation(s)
- Jessica Aceto
- Laboratory for Organogenesis and Regeneration, GIGA- Research, University of Liège, B-4000, Liège, Sart-Tilman, Belgium
| | | | - Raphael Marée
- GIGA & Department of Electrical Engineering and Computer Science, University of Liège, Liège, Belgium
| | - Nadia Dardenne
- Unité de soutien méth. en Biostatistique et Epidémiologie, University of Liège, B23, Sart Tilman, Liège, Belgium
| | - Nathalie Jeanray
- Laboratory for Organogenesis and Regeneration, GIGA- Research, University of Liège, B-4000, Liège, Sart-Tilman, Belgium
| | - Louis Wehenkel
- GIGA & Department of Electrical Engineering and Computer Science, University of Liège, Liège, Belgium
| | - Peter Aleström
- BasAM, Norwegian University of Life Sciences, Vetbio, 0033 Dep, Oslo, Norway
| | - Jack J. W. A. van Loon
- DESC (Dutch Experiment Support Center), Department of Oral and Maxillofacial Surgery / Oral Pathology, VU University Medical Center & Academic Centre for Dentistry Amsterdam (ACTA), Amsterdam, The Netherlands
- ESA-ESTEC, TEC-MMG, NL-2200 AG, Noordwijk, The Netherlands
| | - Marc Muller
- Laboratory for Organogenesis and Regeneration, GIGA- Research, University of Liège, B-4000, Liège, Sart-Tilman, Belgium
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16
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Stooke-Vaughan GA, Obholzer ND, Baxendale S, Megason SG, Whitfield TT. Otolith tethering in the zebrafish otic vesicle requires Otogelin and α-Tectorin. Development 2015; 142:1137-45. [PMID: 25758224 PMCID: PMC4360185 DOI: 10.1242/dev.116632] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Otoliths are biomineralised structures important for balance and hearing in fish. Their counterparts in the mammalian inner ear, otoconia, have a primarily vestibular function. Otoliths and otoconia form over sensory maculae and are attached to the otolithic membrane, a gelatinous extracellular matrix that provides a physical coupling between the otolith and the underlying sensory epithelium. In this study, we have identified two proteins required for otolith tethering in the zebrafish ear, and propose that there are at least two stages to this process: seeding and maintenance. The initial seeding step, in which otolith precursor particles tether directly to the tips of hair cell kinocilia, fails to occur in the einstein (eis) mutant. The gene disrupted in eis is otogelin (otog); mutations in the human OTOG gene have recently been identified as causative for deafness and vestibular dysfunction (DFNB18B). At later larval stages, maintenance of otolith tethering to the saccular macula is dependent on tectorin alpha (tecta) function, which is disrupted in the rolling stones (rst) mutant. α-Tectorin (Tecta) is a major constituent of the tectorial membrane in the mammalian cochlea. Mutations in the human TECTA gene can cause either dominant (DFNA8/12) or recessive (DFNB21) forms of deafness. Our findings indicate that the composition of extracellular otic membranes is highly conserved between mammals and fish, reinforcing the view that the zebrafish is an excellent model system for the study of deafness and vestibular disease.
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Affiliation(s)
| | - Nikolaus D Obholzer
- Department of Systems Biology, Harvard Medical School, 200 Longwood Avenue, Boston, MA 02115, USA
| | - Sarah Baxendale
- Bateson Centre and Department of Biomedical Science, University of Sheffield, Sheffield S10 2TN, UK
| | - Sean G Megason
- Department of Systems Biology, Harvard Medical School, 200 Longwood Avenue, Boston, MA 02115, USA
| | - Tanya T Whitfield
- Bateson Centre and Department of Biomedical Science, University of Sheffield, Sheffield S10 2TN, UK
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17
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Lundberg YW, Xu Y, Thiessen KD, Kramer KL. Mechanisms of otoconia and otolith development. Dev Dyn 2014; 244:239-53. [PMID: 25255879 DOI: 10.1002/dvdy.24195] [Citation(s) in RCA: 96] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2014] [Revised: 08/25/2014] [Accepted: 08/26/2014] [Indexed: 01/17/2023] Open
Abstract
BACKGROUND Otoconia are bio-crystals that couple mechanic forces to the sensory hair cells in the utricle and saccule, a process essential for us to sense linear acceleration and gravity for the purpose of maintaining bodily balance. In fish, structurally similar bio-crystals called otoliths mediate both balance and hearing. Otoconia abnormalities are common and can cause vertigo and imbalance in humans. However, the molecular etiology of these illnesses is unknown, as investigators have only begun to identify genes important for otoconia formation in recent years. RESULTS To date, in-depth studies of selected mouse otoconial proteins have been performed, and about 75 zebrafish genes have been identified to be important for otolith development. CONCLUSIONS This review will summarize recent findings as well as compare otoconia and otolith development. It will provide an updated brief review of otoconial proteins along with an overview of the cells and cellular processes involved. While continued efforts are needed to thoroughly understand the molecular mechanisms underlying otoconia and otolith development, it is clear that the process involves a series of temporally and spatially specific events that are tightly coordinated by numerous proteins. Such knowledge will serve as the foundation to uncover the molecular causes of human otoconia-related disorders.
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Affiliation(s)
- Yunxia Wang Lundberg
- Vestibular Genetics Laboratory, Boys Town National Research Hospital, Omaha, Nebraska
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18
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Ito-Amano M, Nakamura Y, Morisaki M, He X, Hayashi M, Watanapokasin R, Kato H. Temporal and spatial expression patterns of bone morphogenetic protein 3 in developing zebrafish. Open Rheumatol J 2014; 8:69-72. [PMID: 25328556 PMCID: PMC4196250 DOI: 10.2174/1874312901408010069] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2014] [Revised: 07/18/2014] [Accepted: 07/19/2014] [Indexed: 11/22/2022] Open
Abstract
Bone morphogenetic proteins (BMPs) are important elements in bone biology. We herein report the expression profiles of zebrafish bmp3 (zbmp3) as demonstrated by real-time PCR and in situ hybridization. The expression of zbmp3 was highly detectable by real-time PCR from 1 day post-fertilization (1 dpf) to 2 weeks post-fertilization (2 wpf) and peaked at 1 wpf. For in situ hybridization experiments, zbmp3 was expressed in the otic vesicle at 1 dpf, 2 dpf, 3 dpf, and 5 dpf. It was also expressed in the pharyngeal arches, including the opercle, branchiostegal ray, and pectoral fins, at 2 dpf. Our results suggest that zbmp3 may play an important role in the skeletal biology of developing zebrafish.
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Affiliation(s)
- Midori Ito-Amano
- Department of Orthopaedic Surgery, Shinshu University School of Medicine, Asahi 3-1-1, Matsumoto 390-8621, Japan
| | - Yukio Nakamura
- Department of Orthopaedic Surgery, Shinshu University School of Medicine, Asahi 3-1-1, Matsumoto 390-8621, Japan
| | - Mika Morisaki
- Department of Orthopaedic Surgery, Shinshu University School of Medicine, Asahi 3-1-1, Matsumoto 390-8621, Japan
| | - Xinjun He
- Department of Stem Cell and Regenerative Biology, Harvard University, Cambridge, Massachusetts 02138, USA
| | - Masanori Hayashi
- Department of Orthopaedic Surgery, Shinshu University School of Medicine, Asahi 3-1-1, Matsumoto 390-8621, Japan
| | - Ramida Watanapokasin
- Department of Biochemistry, Faculty of Medicine, Srinakharinwirot University, Bangkok 10110, Thailand
| | - Hiroyuki Kato
- Department of Orthopaedic Surgery, Shinshu University School of Medicine, Asahi 3-1-1, Matsumoto 390-8621, Japan
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19
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Lush ME, Piotrowski T. Sensory hair cell regeneration in the zebrafish lateral line. Dev Dyn 2014; 243:1187-202. [PMID: 25045019 DOI: 10.1002/dvdy.24167] [Citation(s) in RCA: 74] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2014] [Revised: 07/12/2014] [Accepted: 07/14/2014] [Indexed: 12/19/2022] Open
Abstract
BACKGROUND Damage or destruction of sensory hair cells in the inner ear leads to hearing or balance deficits that can be debilitating, especially in older adults. Unfortunately, the damage is permanent, as regeneration of the inner ear sensory epithelia does not occur in mammals. RESULTS Zebrafish and other non-mammalian vertebrates have the remarkable ability to regenerate sensory hair cells and understanding the molecular and cellular basis for this regenerative ability will hopefully aid us in designing therapies to induce regeneration in mammals. Zebrafish not only possess hair cells in the ear but also in the sensory lateral line system. Hair cells in both organs are functionally analogous to hair cells in the inner ear of mammals. The lateral line is a mechanosensory system found in most aquatic vertebrates that detects water motion and aids in predator avoidance, prey capture, schooling, and mating. Although hair cell regeneration occurs in both the ear and lateral line, most research to date has focused on the lateral line due to its relatively simple structure and accessibility. CONCLUSIONS Here we review the recent discoveries made during the characterization of hair cell regeneration in zebrafish.
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Affiliation(s)
- Mark E Lush
- Stowers Institute for Medical Research, Kansas City, Missouri
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20
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Bondurand N, Sham MH. The role of SOX10 during enteric nervous system development. Dev Biol 2013; 382:330-43. [DOI: 10.1016/j.ydbio.2013.04.024] [Citation(s) in RCA: 67] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2013] [Accepted: 04/24/2013] [Indexed: 12/30/2022]
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21
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Zamora LY, Lu Z. Alcohol-induced morphological deficits in the development of octavolateral organs of the zebrafish (Danio rerio). Zebrafish 2013; 10:52-61. [PMID: 23461415 DOI: 10.1089/zeb.2012.0830] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
Prenatal alcohol exposure is known to have many profound detrimental effects on human fetal development (fetal alcohol spectrum disorders), which may manifest as lifelong disabilities. However, how alcohol affects the auditory/vestibular system is still largely unknown. This is the first study to investigate morphological effects of alcohol on the developing octavolateral system (the inner ear and lateral line) using the zebrafish, Danio rerio. Zebrafish embryos of 2 hours post fertilization (hpf) were treated in 2% alcohol for 48 hours and screened at 72 hpf for morphological defects of the inner ear and lateral line. Octavolateral organs from both alcohol-treated and control zebrafish were examined using light, confocal, and scanning electron microscopy. We observed several otolith phenotypes for alcohol-treated zebrafish including zero, one, two abnormal, two normal, and multiple otoliths. Results of this study show that alcohol treatment during early development impairs the inner ear (smaller ear, abnormal otoliths, and fewer sensory hair cells) and the lateral line (smaller neuromasts, fewer neuromasts and hair cells per neuromast, and shorter kinocilia of hair cells). Early embryonic alcohol exposure may also result in defects in hearing, balance, and hydrodynamic function of zebrafish.
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Affiliation(s)
- Lilliann Y Zamora
- Department of Biology, University of Miami, 1301 Memorial Drive, Coral Gables, FL 33146, USA
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22
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Obholzer N, Swinburne IA, Schwab E, Nechiporuk AV, Nicolson T, Megason SG. Rapid positional cloning of zebrafish mutations by linkage and homozygosity mapping using whole-genome sequencing. Development 2012; 139:4280-90. [PMID: 23052906 DOI: 10.1242/dev.083931] [Citation(s) in RCA: 66] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Forward genetic screens in zebrafish have identified >9000 mutants, many of which are potential disease models. Most mutants remain molecularly uncharacterized because of the high cost, time and labor investment required for positional cloning. These costs limit the benefit of previous genetic screens and discourage future screens. Drastic improvements in DNA sequencing technology could dramatically improve the efficiency of positional cloning in zebrafish and other model organisms, but the best strategy for cloning by sequencing has yet to be established. Using four zebrafish inner ear mutants, we developed and compared two approaches for 'cloning by sequencing': one based on bulk segregant linkage (BSFseq) and one based on homozygosity mapping (HMFseq). Using BSFseq we discovered that mutations in lmx1b and jagged1b cause abnormal ear morphogenesis. With HMFseq we validated that the disruption of cdh23 abolishes the ear's sensory functions and identified a candidate lesion in lhfpl5a predicted to cause nonsyndromic deafness. The success of HMFseq shows that the high intrastrain polymorphism rate in zebrafish eliminates the need for time-consuming map crosses. Additionally, we analyzed diversity in zebrafish laboratory strains to find areas of elevated diversity and areas of fixed homozygosity, reinforcing recent findings that genome diversity is clustered. We present a database of >15 million sequence variants that provides much of this approach's power. In our four test cases, only a single candidate single nucleotide polymorphism (SNP) remained after subtracting all database SNPs from a mutant's critical region. The saturation of the common SNP database and our open source analysis pipeline MegaMapper will improve the pace at which the zebrafish community makes unique discoveries relevant to human health.
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Affiliation(s)
- Nikolaus Obholzer
- Department of Systems Biology, Harvard Medical School, 200 Longwood Avenue, Boston, MA 02115, USA
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23
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Stooke-Vaughan GA, Huang P, Hammond KL, Schier AF, Whitfield TT. The role of hair cells, cilia and ciliary motility in otolith formation in the zebrafish otic vesicle. Development 2012; 139:1777-87. [PMID: 22461562 DOI: 10.1242/dev.079947] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Otoliths are biomineralised structures required for the sensation of gravity, linear acceleration and sound in the zebrafish ear. Otolith precursor particles, initially distributed throughout the otic vesicle lumen, become tethered to the tips of hair cell kinocilia (tether cilia) at the otic vesicle poles, forming two otoliths. We have used high-speed video microscopy to investigate the role of cilia and ciliary motility in otolith formation. In wild-type ears, groups of motile cilia are present at the otic vesicle poles, surrounding the immotile tether cilia. A few motile cilia are also found on the medial wall, but most cilia (92-98%) in the otic vesicle are immotile. In mutants with defective cilia (iguana) or ciliary motility (lrrc50), otoliths are frequently ectopic, untethered or fused. Nevertheless, neither cilia nor ciliary motility are absolutely required for otolith tethering: a mutant that lacks cilia completely (MZovl) is still capable of tethering otoliths at the otic vesicle poles. In embryos with attenuated Notch signalling [mindbomb mutant or Su(H) morphant], supernumerary hair cells develop and otolith precursor particles bind to the tips of all kinocilia, or bind directly to the hair cells' apical surface if cilia are absent [MZovl injected with a Su(H)1+2 morpholino]. However, if the first hair cells are missing (atoh1b morphant), otolith formation is severely disrupted and delayed. Our data support a model in which hair cells produce an otolith precursor-binding factor, normally localised to tether cell kinocilia. We also show that embryonic movement plays a minor role in the formation of normal otoliths.
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Affiliation(s)
- Georgina A Stooke-Vaughan
- MRC Centre for Developmental and Biomedical Genetics and Department of Biomedical Science, University of Sheffield, Sheffield, S10 2TN, UK
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24
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Malicki J, Avanesov A, Li J, Yuan S, Sun Z. Analysis of cilia structure and function in zebrafish. Methods Cell Biol 2011; 101:39-74. [PMID: 21550439 DOI: 10.1016/b978-0-12-387036-0.00003-7] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
The cilium, a previously little studied cell surface protrusion, has emerged as an important organelle in vertebrate cells. This tiny structure is essential for normal embryonic development, including the formation of left-right asymmetry, limb morphogenesis, and the differentiation of sensory cells. In the adult, cilia also function in a variety of processes, such as the survival of photoreceptor cells, and the homeostasis in several tissues, including the epithelia of nephric ducts. Human ciliary malfunction is associated with situs inversus, kidney cysts, polydactyly, blindness, mental retardation, obesity, and many other abnormalities. The genetic accessibility and optical transparency of the zebrafish make it an excellent vertebrate model system to study cilia biology. In this chapter, we describe the morphology and distribution of cilia in zebrafish embryonic and larval organs. We also provide essential protocols to analyze cilia formation and function.
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Affiliation(s)
- Jarema Malicki
- Division of Craniofacial and Molecular Genetics, Tufts University, Massachusetts, USA
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25
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Clendenon SG, Shah B, Miller CA, Schmeisser G, Walter A, Gattone VH, Barald KF, Liu Q, Marrs JA. Cadherin-11 controls otolith assembly: evidence for extracellular cadherin activity. Dev Dyn 2009; 238:1909-22. [PMID: 19582870 DOI: 10.1002/dvdy.22015] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
Cadherin-11/Cdh11 is expressed through early development and strongly during inner ear development (otic placode and vesicle). Here we show that antisense knockdown of Cdh11 during early zebrafish development interferes with otolith formation. Immunofluorescence labeling showed that Cdh11 expression was concentrated on and within the otolith. Cdh11 was faintly detected at the lateral surface (sites of cell-cell contact) of otic epithelial cells and in the cytoplasm. Strongly labeled Cdh11 containing puncta were detected within the otolymph (the fluid within the otic vesicle) and associated with the otolith surface. BODIPY-ceramine-labeled vesicular structures detected in the otolymph were larger and more numerous in Cdh11 knockdown embryos. We present evidence supporting a working model that vesicular structures containing Cdh11 (perhaps containing biomineralization components) are exported from the otic epithelium into the otolymph, adhere to one another and to the surface of the growing otolith, facilitating otolith growth.
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Affiliation(s)
- Sherry G Clendenon
- Department of Medicine, Indiana University Medical Center, Indianapolis, Indiana 46202-5130, USA
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26
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Petko JA, Kabbani N, Frey C, Woll M, Hickey K, Craig M, Canfield VA, Levenson R. Proteomic and functional analysis of NCS-1 binding proteins reveals novel signaling pathways required for inner ear development in zebrafish. BMC Neurosci 2009; 10:27. [PMID: 19320994 PMCID: PMC2679751 DOI: 10.1186/1471-2202-10-27] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2008] [Accepted: 03/25/2009] [Indexed: 01/11/2023] Open
Abstract
BACKGROUND The semicircular canals, a subdivision of the vestibular system of the vertebrate inner ear, function as sensors of angular acceleration. Little is currently known, however, regarding the underlying molecular mechanisms that govern the development of this intricate structure. Zebrafish represent a particularly tractable model system for the study of inner ear development. This is because the ear can be easily visualized during early embryogenesis, and both forward and reverse genetic techniques are available that can be applied to the discovery of novel genes that contribute to proper ear development. We have previously shown that in zebrafish, the calcium sensing molecule neuronal calcium sensor-1 (NCS-1) is required for semicircular canal formation. The function of NCS-1 in regulating semicircular canal formation has not yet been elucidated. RESULTS We initiated a multistep functional proteomic strategy to identify neuronal calcium sensor-1 (NCS-1) binding partners (NBPs) that contribute to inner ear development in zebrafish. By performing a Y2H screen in combination with literature and database searches, we identified 10 human NBPs. BLAST searches of the zebrafish EST and genomic databases allowed us to clone zebrafish orthologs of each of the human NBPs. By investigating the expression profiles of zebrafish NBP mRNAs, we identified seven that were expressed in the developing inner ear and overlapped with the ncs-1a expression profile. GST pulldown experiments confirmed that selected NBPs interacted with NCS-1, while morpholino-mediated knockdown experiments demonstrated an essential role for arf1, pi4kbeta, dan, and pink1 in semicircular canal formation. CONCLUSION Based on their functional profiles, the hypothesis is presented that Ncs-1a/Pi4kbeta/Arf1 form a signaling pathway that regulates secretion of molecular components, including Dan and Bmp4, that are required for development of the vestibular apparatus. A second set of NBPs, consisting of Pink1, Hint2, and Slc25a25, are destined for localization in mitochondria. Our findings reveal a novel signalling pathway involved in development of the semicircular canal system, and suggest a previously unrecognized role for NCS-1 in mitochondrial function via its association with several mitochondrial proteins.
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Affiliation(s)
- Jessica A Petko
- Department of Pharmacology, Penn State College of Medicine, 500 University Drive, Hershey PA 17033, USA.
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27
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Esaki M, Hoshijima K, Nakamura N, Munakata K, Tanaka M, Ookata K, Asakawa K, Kawakami K, Wang W, Weinberg ES, Hirose S. Mechanism of development of ionocytes rich in vacuolar-type H(+)-ATPase in the skin of zebrafish larvae. Dev Biol 2009; 329:116-29. [PMID: 19268451 DOI: 10.1016/j.ydbio.2009.02.026] [Citation(s) in RCA: 62] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2008] [Revised: 02/23/2009] [Accepted: 02/24/2009] [Indexed: 11/17/2022]
Abstract
Mitochondrion-rich cells (MRCs), or ionocytes, play a central role in aquatic species, maintaining body fluid ionic homeostasis by actively taking up or excreting ions. Since their first description in 1932 in eel gills, extensive morphological and physiological analyses have yielded important insights into ionocyte structure and function, but understanding the developmental pathway specifying these cells remains an ongoing challenge. We previously succeeded in identifying a key transcription factor, Foxi3a, in zebrafish larvae by database mining. In the present study, we analyzed a zebrafish mutant, quadro (quo), deficient in foxi1 gene expression and found that foxi1 is essential for development of an MRC subpopulation rich in vacuolar-type H(+)-ATPase (vH-MRC). foxi1 acts upstream of Delta-Notch signaling that determines sporadic distribution of vH-MRC and regulates foxi3a expression. Through gain- and loss-of-function assays and cell transplantation experiments, we further clarified that (1) the expression level of foxi3a is maintained by a positive feedback loop between foxi3a and its downstream gene gcm2 and (2) Foxi3a functions cell-autonomously in the specification of vH-MRC. These observations provide a better understanding of the differentiation and distribution of the vH-MRC subtype.
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Affiliation(s)
- Masahiro Esaki
- Department of Biological Sciences, Tokyo Institute of Technology, Midori-ku, Yokohama, Japan
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28
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Brignull HR, Raible DW, Stone JS. Feathers and fins: non-mammalian models for hair cell regeneration. Brain Res 2009; 1277:12-23. [PMID: 19245801 DOI: 10.1016/j.brainres.2009.02.028] [Citation(s) in RCA: 105] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2009] [Revised: 02/09/2009] [Accepted: 02/11/2009] [Indexed: 11/18/2022]
Abstract
Death of mechanosensory cells in the inner ear results in two profound disabilities: hearing loss and balance disorders. Although mammals lack the capacity to regenerate hair cells, recent studies in mice and other rodents have offered valuable insight into strategies for stimulating hair cell regeneration in mammals. Investigations of model organisms that retain the ability to form new hair cells after embryogenesis, such as fish and birds, are equally important and have provided clues as to the cellular and molecular mechanisms that may block hair cell regeneration in mammals. Here, we summarize studies on hair cell regeneration in the chicken and the zebrafish, discuss specific advantages of each model, and propose future directions for the use of non-mammalian models in understanding hair cell regeneration.
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Affiliation(s)
- Heather R Brignull
- Department of Biological Structure, University of Washington, WA 98195-7420, USA.
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29
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Kremer H, Cremers FPM. Positional cloning of deafness genes. Methods Mol Biol 2009; 493:215-238. [PMID: 18839350 DOI: 10.1007/978-1-59745-523-7_13] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
The identification of the majority of the known causative genes involved in nonsyndromic sensorineural hearing loss (NSHL) started with linkage analysis as part of a positional cloning procedure. The human and mouse genome projects in combination with technical developments on genotyping, transcriptomics, proteomics, and the creation of animal models have greatly enhanced the speed of disease gene identification. In the present chapter, we first discuss the possibilities for exclusion of known NSHL loci and genes. Subsequently, methods are described to determine the genomic regions that contain the genetic defects. These include linkage analysis with genotyping and statistical evaluation and the determination of copy number variations. In the case of a large genomic region, candidate genes are selected and prioritized using gene expression analysis, protein network data, and phenotypes of animal models. A number of algorithms are described to automate the process of candidate gene selection. The novel high-throughput sequencing techniques might make gene selection and prioritization unnecessary in the near future. Once genetic variants are identified, questions on pathogenicity need to be addressed, which is the topic of the last section of this chapter.
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Affiliation(s)
- Hannie Kremer
- Department of Otorhinolaryngology, Nijmegen Centre for Molecular Life Sciences, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands
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30
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A functional screen for genes involved in Xenopus pronephros development. Mech Dev 2008; 125:571-86. [PMID: 18472403 DOI: 10.1016/j.mod.2008.03.001] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2008] [Revised: 03/05/2008] [Accepted: 03/08/2008] [Indexed: 11/23/2022]
Abstract
In Xenopus, the pronephros is the functional larval kidney and consists of two identifiable components; the glomus, the pronephric tubules, which can be divided into four separate segments, based on marker gene expression. The simplicity of this organ, coupled with the fact that it displays the same basic organization and function as more complex mesonephros and metanephros, makes this an attractive model to study vertebrate kidney formation. In this study, we have performed a functional screen specifically to identify genes involved in pronephros development in Xenopus. Gain-of-function screens are performed by injecting mRNA pools made from a non-redundant X. tropicalis full-length plasmid cDNA library into X. laevis eggs, followed by sib-selection to identify the single clone that caused abnormal phenotypes in the pronephros. Out of 768 egg and gastrula stage cDNA clones, 31 genes, approximately 4% of the screened clones, affected pronephric marker expression examined by whole mount in situ hybridization or antibody staining. Most of the positive clones had clear expression patterns in pronephros and predicted/established functions highly likely to be involved in developmental processes. In order to carry out a more detailed study, we selected Sox7, Cpeb3, P53csv, Mecr and Dnajc15, which had highly specific expression patterns in the pronephric region. The over-expression of these five selected clones indicated that they caused pronephric abnormalities with different temporal and spatial effects. These results suggest that our strategy to identify novel genes involved in pronephros development was highly successful, and that this strategy is effective for the identification of novel genes involved in late developmental events.
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31
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Burket CT, Montgomery JE, Thummel R, Kassen SC, LaFave MC, Langenau DM, Zon LI, Hyde DR. Generation and characterization of transgenic zebrafish lines using different ubiquitous promoters. Transgenic Res 2007; 17:265-79. [PMID: 17968670 DOI: 10.1007/s11248-007-9152-5] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2007] [Accepted: 10/09/2007] [Indexed: 01/24/2023]
Abstract
Two commonly used promoters to ubiquitously express transgenes in zebrafish are the Xenopus laevis elongation factor 1 alpha promoter (XlEef1a1) and the zebrafish histone variant H2A.F/Z (h2afv) promoter. Recently, transgenes utilizing these promoters were shown to be silenced in certain adult tissues, particularly the central nervous system. To overcome this limitation, we cloned the promoters of four zebrafish genes that likely are transcribed ubiquitously throughout development and into the adult. These four genes are the TATA box binding protein gene, the taube nuss-like gene, the eukaryotic elongation factor 1-gamma gene, and the beta-actin-1 gene. We PCR amplified approximately 2.5 kb upstream of the putative translational start site of each gene and cloned each into a Tol2 expression vector that contains the EGFP reporter transgene. We used these four Tol2 vectors to independently generate stable transgenic fish lines for analysis of transgene expression during development and in the adult. We demonstrated that all four promoters drive a very broad pattern of EGFP expression throughout development and the adult. Using the retina as a well-characterized component of the CNS, all four promoters appeared to drive EGFP expression in all neuronal and non-neuronal cells of the adult retina. In contrast, the h2afv promoter failed to express EGFP in the adult retina. When we examined EGFP expression in the various cells of the blood cell lineage, we observed that all four promoters exhibited a more heterogenous expression pattern than either the XlEef1a1 or h2afv promoters. While these four ubiquitous promoters did not express EGFP in all the adult blood cells, they did express EGFP throughout the CNS and in broader expression patterns in the adult than either the XlEef1a1 or h2afv promoters. For these reasons, these four promoters will be valuable tools for expressing transgenes in adult zebrafish.
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Affiliation(s)
- Christopher T Burket
- Department of Biological Sciences and the Center for Zebrafish Research, University of Notre Dame, Notre Dame, IN 46556, USA
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32
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Nemoto Y, Chatani M, Inohaya K, Hiraki Y, Kudo A. Expression of marker genes during otolith development in medaka. Gene Expr Patterns 2007; 8:92-5. [PMID: 17981516 DOI: 10.1016/j.modgep.2007.10.001] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2007] [Revised: 10/02/2007] [Accepted: 10/05/2007] [Indexed: 11/16/2022]
Abstract
Little is known about the genes and processes involved in the development of otoliths. In this study, we isolated the biomineralization-related genes otolin and chondromodulin-1 (chm1) from medaka, and examined their spatiotemporal expression pattern as well as that of two other genes also related to biomineralization, i.e., sparc/osteonectin and type II collagen (col2a), during otic development in medaka. Our results demonstrated that all the tested genes were expressed in the otic vesicle, and that chm1 was exclusively expressed in the semicircular canal of the otic vesicle.
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Affiliation(s)
- Yoshiyuki Nemoto
- Department of Biological Information, Tokyo Institute of Technology, Yokohama 226-8501, Japan
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33
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Schibler A, Malicki J. A screen for genetic defects of the zebrafish ear. Mech Dev 2007; 124:592-604. [PMID: 17574823 DOI: 10.1016/j.mod.2007.04.005] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2006] [Revised: 04/13/2007] [Accepted: 04/19/2007] [Indexed: 10/23/2022]
Abstract
To advance the understanding of genetic mechanisms involved in the patterning and the differentiation of the vertebrate auditory system, we screened for mutations affecting ear development in the zebrafish larva. Fifteen recessive mutant alleles have been isolated and analyzed. The phenotypes of these mutants involve abnormalities in ear morphology, otolith formation, or both processes in parallel. Among morphological defects, we found mutations affecting early patterning of the otic vesicle, the morphogenesis of semicircular canals, and the expansion of the ear lumen. The two most severe mutant phenotypes involve the absence of anterior and posterior cristae, as well as a severely misshapen morphology of the ear. In the category of otolith mutants, we found defects in otolith formation, growth, and shape. As it proved to be the case in past screening efforts of this type, these mutant lines represent an asset in the studies of molecular mechanisms that regulate vertebrate ear development.
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Affiliation(s)
- Andria Schibler
- Department of Ophthalmology, Harvard Medical School, 243 Charles Street, Boston, MA 02114, USA
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34
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Blaser R, Gerlai R. Behavioral phenotyping in zebrafish: comparison of three behavioral quantification methods. Behav Res Methods 2007; 38:456-69. [PMID: 17186756 DOI: 10.3758/bf03192800] [Citation(s) in RCA: 199] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The zebrafish has been popular in developmental biology and genetics, but its brain function has rarely been studied. High-throughput screening of mutation or drug-induced changes in brain function requires simple and automatable behavioral tests. This article compares three behavioral quantification methods in four simple behavioral paradigms that test a range of characteristics of adult zebrafish, including novelty-induced responses, social behavior, aggression, and predator-model-induced responses. Two quantification methods, manual recording and computerized videotracking of location and activity, yielded very similar results, suggesting that automated videotracking reliably measures activity parameters and will allow high-throughput screening. However, observation-based event recording of posture patterns was found generally not to correlate with videotracking measures, suggesting that further refinement of automated behavior quantification may be considered.
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Affiliation(s)
- Rachel Blaser
- University of Hawaii at Manoa, Honolulu, Hawaii, USA
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35
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Abstract
For both vertebrate developmental and evolutionary biologists, and also for clinicians, the neural crest (NC) is a fundamental cell population. An understanding of Sox10 function in NC development is of particular significance since Sox10 mutations underlie several neurocristopathies. Surprisingly, experiments in different model organisms aimed at identifying Sox10's role(s) have suggested at least four distinct functions. Sox10 may be critical for formation of neural crest cells (NCCs), maintaining multipotency of crest cells, specification of derivative cell fates from these cells and their differentiation. Here, I discuss this controversy and argue that these functions are, in part, molecularly interrelated.
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Affiliation(s)
- Robert N Kelsh
- Centre for Regenerative Medicine, University of Bath, Department of Biology and Biochemistry, Claverton Down, Bath BA2 7AY, UK.
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36
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Hammond CL, Hinits Y, Osborn DP, Minchin JE, Tettamanti G, Hughes SM. Signals and myogenic regulatory factors restrict pax3 and pax7 expression to dermomyotome-like tissue in zebrafish. Dev Biol 2006; 302:504-21. [PMID: 17094960 PMCID: PMC3960072 DOI: 10.1016/j.ydbio.2006.10.009] [Citation(s) in RCA: 115] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2006] [Revised: 09/26/2006] [Accepted: 10/05/2006] [Indexed: 11/22/2022]
Abstract
Pax3/7 paired homeodomain transcription factors are important markers of muscle stem cells. Pax3 is required upstream of myod for lateral dermomyotomal cells in the amniote somite to form particular muscle cells. Later Pax3/7-dependent cells generate satellite cells and most body muscle. Here we analyse early myogenesis from, and regulation of, a population of Pax3-expressing dermomyotome-like cells in the zebrafish. Zebrafish pax3 is widely expressed in the lateral somite and, along with pax7, becomes restricted anteriorly and then to the external cells on the lateral somite surface. Midline-derived Hedgehog signals appear to act directly on lateral somite cells to repress Pax3/7. Both Hedgehog and Fgf8, signals that induce muscle formation within the somite, suppress Pax3/7 and promote expression of myogenic regulatory factors (MRFs) myf5 and myod in specific muscle precursor cell populations. Loss of MRF function leads to loss of myogenesis by specific populations of muscle fibres, with parallel up-regulation of Pax3/7. Myod is required for lateral fast muscle differentiation from pax3-expressing cells. In contrast, either Myf5 or Myod is sufficient to promote slow muscle formation from adaxial cells. Thus, myogenic signals act to drive somite cells to a myogenic fate through up-regulation of distinct combinations of MRFs. Our data show that the relationship between Pax3/7 genes and myogenesis is evolutionarily ancient, but that changes in the MRF targets for particular signals contribute to myogenic differences between species.
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Affiliation(s)
| | | | | | | | | | - Simon M. Hughes
- Corresponding author: Simon M. Hughes, 4 floor South, New Hunt’s House, Guy’s Campus, King’s College London, London SE1 1UL, UK tel: +44 (0)20 7848 6445, fax+44 (0)20 7848 6798,
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37
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Sison M, Cawker J, Buske C, Gerlai R. Fishing for genes influencing vertebrate behavior: zebrafish making headway. Lab Anim (NY) 2006; 35:33-9. [PMID: 16645614 DOI: 10.1038/laban0506-33] [Citation(s) in RCA: 102] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2005] [Accepted: 03/13/2006] [Indexed: 11/08/2022]
Abstract
The zebrafish (Danio rerio) has been a favorite model of developmental biologists and geneticists, but only recently have investigators begun to appreciate its usefulness in behavior genetics. Papers focusing on the behavior or brain function of this species were once extremely rare, but during the past decade rapid growth has taken place. Despite the increased interest, however, the number of studies devoted to the analysis of the behavior of this species is still orders of magnitude less than those conducted on more traditional laboratory subjects including the rat and the mouse. The authors review selected literature and demonstrate that zebrafish is an excellent subject for behavior genetics research, especially in the area of forward genetics (mutagenesis).
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Affiliation(s)
- Margarette Sison
- Department of Psychology, University of Toronto at Mississauga, 3359 Mississauga Rd., Mississauga, ON Canada
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38
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Jones SM, Johnson KR, Yu H, Erway LC, Alagramam KN, Pollak N, Jones TA. A quantitative survey of gravity receptor function in mutant mouse strains. J Assoc Res Otolaryngol 2006; 6:297-310. [PMID: 16235133 PMCID: PMC2504620 DOI: 10.1007/s10162-005-0009-4] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2004] [Accepted: 06/20/2005] [Indexed: 02/04/2023] Open
Abstract
The purpose of this research was to identify vestibular deficits in mice using linear vestibular evoked potentials (VsEPs). VsEP thresholds, peak latencies, and peak amplitudes from 24 strains with known genetic mutations and 6 inbred background strains were analyzed and descriptive statistics generated for each strain. Response parameters from mutant homozygotes were compared with heterozygote and/or background controls and all strain averages were contrasted to normative ranges. Homozygotes of the following recessive mutations had absent VsEPs at the ages tested: Espn(je), Atp2b2dfw-2J, Spnb4qv-lnd2J, Spnb4qv-3J, Myo7ash1, Tmie(sr), Myo6sv, jc, Pcdh15av-J, Pcdh15av-2J, Pcdh15av-3J, Cdh23v-2J, Sans(js), hr, Kcne1pkr and Pou3f4del. These results suggest profound gravity receptor deficits for these homozygotes, which is consistent with the structural deficits that have been documented for many of these strains. Homozygotes of Catna2cdf, Grid2ho4J, Wnt1sw, qk, and Mbpshi strains and heterozygotes of Grid2lc had measurable VsEPs but one or more response parameters differed from the respective control group (heterozygote or background strain) or were outside normal ranges. For example, qk and Mbpshi homozygotes showed significantly prolonged latencies consistent with the abnormal myelin that has been described for these strains. Prolonged latencies may suggest deficits in neural conduction; elevated thresholds suggest reduced sensitivity, and reduced amplitudes may be suggestive for reduced neural synchrony. One mutation, Otx1jv, had all VsEP response parameters within normal limits--an expected finding because the abnormality in Otxljv is presumably restricted to the lateral semicircular canal. Interestingly, some heterozygote groups also showed abnormalities in one or more VsEP response parameters, suggesting that vestibular dysfunction, although less severe, may be present in some heterozygous animals.
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Affiliation(s)
- Sherri M Jones
- Department of Communication Sciences and Disorders, East Carolina University, Greenville, NC 27858, USA.
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39
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Matsui JI, Parker MA, Ryals BM, Cotanche DA. Regeneration and replacement in the vertebrate inner ear. Drug Discov Today 2005; 10:1307-12. [PMID: 16214675 DOI: 10.1016/s1359-6446(05)03577-4] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
Deafness affects more than 40 million people in the UK and the USA, and many more world-wide. The primary cause of hearing loss is damage to or death of the sensory receptor cells in the inner ear, the hair cells. Birds can readily regenerate their cochlear hair cells but the mammalian cochlea has shown no ability to regenerate after damage. Current research efforts are focusing on gene manipulation, gene therapy and stem cell transplantation for repairing or replacing damaged mammalian cochlear hair cells, which could lead to therapies for treating deafness in humans.
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Affiliation(s)
- Jonathan I Matsui
- Laboratory for Cellular and Molecular Hearing Research, Department of Otolaryngology, Children's Hospital, Boston, MA 02115, USA
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40
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Pickart MA, Sivasubbu S, Nielsen AL, Shriram S, King RA, Ekker SC. Functional genomics tools for the analysis of zebrafish pigment. ACTA ACUST UNITED AC 2005; 17:461-70. [PMID: 15357832 DOI: 10.1111/j.1600-0749.2004.00189.x] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
Genetic model organisms are increasingly valuable in the post-genomics era to provide a basis for comparative analysis of the human genome. For higher order processes of vertebrate pigment cell biology and development, the mouse has historically been the model of choice. A complementary organism, the zebrafish (Danio rerio), shares many of the signaling and biological processes of vertebrates, e.g. neural crest development. The zebrafish has a number of characteristics that make it an especially valuable model for the study of pigment cell biology and disease. Large-scale genetic screens have identified a collection of pigmentation mutants that have already made valuable contributions to pigment research. An increasing repertoire of genomic resources such as an expressed sequence tag-based Gene Index (The Institute for Genomic Research) and improving methods of mutagenesis, transgenesis, and gene targeting make zebrafish a particularly attractive model. Morpholino phosphorodiamidate oligonucleotide (MO) 'knockdown' of pigment gene expression provides a non-conventional antisense tool for the analysis of genes involved in pigment cell biology and disease. In addition, an ongoing, reverse-genetic, MO-based screen for the rapid identification of gene function promises to be a valuable complement to other high-throughput microarray and proteomic approaches for understanding pigment cell biology. Novel reagents for zebrafish transgenesis, such as the Sleeping Beauty transposon system, continue to improve the capacity for genetic analysis in this system and ensure that the zebrafish will be a valuable genetic model for understanding a variety of biological processes and human diseases for years to come.
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Affiliation(s)
- Michael A Pickart
- Department of Oral Sciences and Minnesota Craniofacial Research Training Program (MinnCResT), University of Minnesota, Minneapolis, MN, USA
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41
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Noramly S, Zimmerman L, Cox A, Aloise R, Fisher M, Grainger RM. A gynogenetic screen to isolate naturally occurring recessive mutations in Xenopus tropicalis. Mech Dev 2005; 122:273-87. [PMID: 15763208 DOI: 10.1016/j.mod.2004.11.001] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2004] [Revised: 10/27/2004] [Accepted: 11/04/2004] [Indexed: 10/25/2022]
Abstract
In the rapidly developing, diploid amphibian Xenopus tropicalis, genetics can be married to the already powerful tools of the amphibian system to overcome a disability that has hampered Xenopus laevis as a model organism: the difficulties inherent in conducting genetic analyses in a tetraploid organism with a longer generation time. We describe here a gynogenetic screen to uncover naturally occurring recessive mutations in wild X. tropicalis populations, a procedure that is both faster and easier than conventional genetic screens traditionally employed in model organisms to dissect early developmental pathways. During the first round of our screen, gynogenetic diploids from over 160 females comprising four different wild-caught populations were examined. Forty-two potential mutant phenotypes were isolated during this round of gynogenesis. From this group, we describe 10 lines that have genetically heritable recessive mutations. A wide range of developmental defects were obtained in this screen, encompassing effects limited to individual organs as well phenotypes characterized by more global changes in tadpole body morphology. The frequency of recessive mutations detected in our screen appears lower than that seen in other vertebrate genetic screens, but given constraints on the screening procedure used here, is likely to be consistent with rates seen in other animals, and clearly illustrates how wild-caught animals can be a productive source of developmental mutations for experimental study. The development of genetic strategies for the Xenopus system, together with new genomic resources, existing technologies for transgenesis, and other means for manipulating gene expression, as well as the power of performing embryonic manipulations, will provide an impressive set of tools for resolving complex cell and developmental phenomena in the future.
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Affiliation(s)
- Selina Noramly
- Department of Biology, University of Virginia, Gilmer Hall, Charlottesville, VA 22904, USA
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42
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Kelsh RN, Inoue C, Momoi A, Kondoh H, Furutani-Seiki M, Ozato K, Wakamatsu Y. The Tomita collection of medaka pigmentation mutants as a resource for understanding neural crest cell development. Mech Dev 2005; 121:841-59. [PMID: 15210190 DOI: 10.1016/j.mod.2004.01.004] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2003] [Revised: 11/17/2003] [Accepted: 11/25/2003] [Indexed: 12/29/2022]
Abstract
All body pigment cells in vertebrates are derived from the neural crest. In fish the neural crest can generate up to six different types of pigment cells, as well as various non-pigmented derivatives. In mouse and zebrafish, extensive collections of pigmentation mutants have enabled dissection of many aspects of pigment cell development, including fate specification, survival, proliferation and differentiation. A collection of spontaneous mutations collected from wild medaka (Oryzias latipes) populations and maintained at Nagoya University includes more than 40 pigmentation mutations. The descriptions of their adult phenotypes have been previously published by Tomita and colleagues (summarised in Medaka (Killifish) Biology and Strains, 1975), but the embryonic phenotypes have not been systematically described. Here we examine these embryonic phenotypes, paying particular attention to the likely defect in pigment cell development in each, and comparing the spectrum of defects to those in the zebrafish and mouse collections. Many phenotypes parallel those of identified zebrafish mutants, although pigment cell death phenotypes are largely absent, presumably due to the different selective pressures under which the mutants were isolated. We have identified mutant phenotypes that may represent the Mitf/Kit pathway of melanophore specification and survival. We use in situ hybridisation with available markers to confirm a key prediction of this hypothesis. We also highlight a set of novel phenotypes not seen in the zebrafish collection. These mutants will be a valuable resource for pigment cell and neural crest studies and will strongly complement the mutant collections in other vertebrates.
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Affiliation(s)
- Robert N Kelsh
- Developmental Biology Programme, Department of Biology and Biochemistry, Centre for Regenerative Medicine, University of Bath, Claverton Down, Bath BA2 7AY, UK.
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43
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Kozlowski DJ, Whitfield TT, Hukriede NA, Lam WK, Weinberg ES. The zebrafish dog-eared mutation disrupts eya1, a gene required for cell survival and differentiation in the inner ear and lateral line. Dev Biol 2005; 277:27-41. [PMID: 15572137 DOI: 10.1016/j.ydbio.2004.08.033] [Citation(s) in RCA: 95] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2004] [Revised: 08/17/2004] [Accepted: 08/20/2004] [Indexed: 11/19/2022]
Abstract
To understand the molecular basis of sensory organ development and disease, we have cloned and characterized the zebrafish mutation dog-eared (dog) that is defective in formation of the inner ear and lateral line sensory systems. The dog locus encodes the eyes absent-1 (eya1) gene and single point mutations were found in three independent dog alleles, each prematurely truncating the expressed protein within the Eya domain. Moreover, morpholino-mediated knockdown of eya1 gene function phenocopies the dog-eared mutation. In zebrafish, the eya1 gene is widely expressed in placode-derived sensory organs during embryogenesis but Eya1 function appears to be primarily required for survival of sensory hair cells in the developing ear and lateral line neuromasts. Increased levels of apoptosis occur in the migrating primordia of the posterior lateral line in dog embryos and as well as in regions of the developing otocyst that are mainly fated to give rise to sensory cells of the cristae. Importantly, mutation of the EYA1 or EYA4 gene causes hereditary syndromic deafness in humans. Determination of eya gene function during zebrafish organogenesis will facilitate understanding the molecular etiology of human vestibular and hearing disorders.
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Affiliation(s)
- David J Kozlowski
- Department of Biology, University of Pennsylvania, Philadelphia, PA 19104, USA
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44
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Abstract
The zebrafish has become a widely used model organism because of its fecundity, its morphological and physiological similarity to mammals, the existence of many genomic tools and the ease with which large, phenotype-based screens can be performed. Because of these attributes, the zebrafish might also provide opportunities to accelerate the process of drug discovery. By combining the scale and throughput of in vitro screens with the physiological complexity of animal studies, the zebrafish promises to contribute to several aspects of the drug development process, including target identification, disease modelling, lead discovery and toxicology.
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Affiliation(s)
- Leonard I Zon
- Howard Hughes Medical Institute, Division of Hematology/Oncology, Children's Hospital, Harvard Medical School, Boston, Massachusetts 02115, USA
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45
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Sims RJ, Belotserkovskaya R, Reinberg D. Elongation by RNA polymerase II: the short and long of it. Genes Dev 2004; 18:2437-68. [PMID: 15489290 DOI: 10.1101/gad.1235904] [Citation(s) in RCA: 533] [Impact Index Per Article: 26.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Appreciable advances into the process of transcript elongation by RNA polymerase II (RNAP II) have identified this stage as a dynamic and highly regulated step of the transcription cycle. Here, we discuss the many factors that regulate the elongation stage of transcription. Our discussion includes the classical elongation factors that modulate the activity of RNAP II, and the more recently identified factors that facilitate elongation on chromatin templates. Additionally, we discuss the factors that associate with RNAP II, but do not modulate its catalytic activity. Elongation is highlighted as a central process that coordinates multiple stages in mRNA biogenesis and maturation.
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Affiliation(s)
- Robert J Sims
- Howard Hughes Medical Institute, Robert Wood Johnson Medical School, Piscataway, New Jersey 08854, USA
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Hughes I, Blasiole B, Huss D, Warchol ME, Rath NP, Hurle B, Ignatova E, Dickman JD, Thalmann R, Levenson R, Ornitz DM. Otopetrin 1 is required for otolith formation in the zebrafish Danio rerio. Dev Biol 2004; 276:391-402. [PMID: 15581873 PMCID: PMC2522322 DOI: 10.1016/j.ydbio.2004.09.001] [Citation(s) in RCA: 80] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2004] [Revised: 08/30/2004] [Accepted: 09/02/2004] [Indexed: 11/23/2022]
Abstract
Orientation with respect to gravity is essential for the survival of complex organisms. The gravity receptor is one of the phylogenetically oldest sensory systems, and special adaptations that enhance sensitivity to gravity are highly conserved. The fish inner ear contains three large extracellular biomineral particles, otoliths, which have evolved to transduce the force of gravity into neuronal signals. Mammalian ears contain thousands of small particles called otoconia that serve a similar function. Loss or displacement of these structures can be lethal for fish and is responsible for benign paroxysmal positional vertigo (BPPV) in humans. The distinct morphologies of otoconial particles and otoliths suggest divergent developmental mechanisms. Mutations in a novel gene Otopetrin 1 (Otop1), encoding multi-transmembrane domain protein, result in nonsyndromic otoconial agenesis and a severe balance disorder in mice. Here we show that the zebrafish, Danio rerio, contains a highly conserved gene, otop1, that is essential for otolith formation. Morpholino-mediated knockdown of zebrafish Otop1 leads to otolith agenesis without affecting the sensory epithelium or other structures within the inner ear. Despite lack of otoliths in early development, otolith formation partially recovers in some fish after 2 days. However, the otoliths are malformed, misplaced, lack an organic matrix, and often consist of inorganic calcite crystals. These studies demonstrate that Otop1 has an essential and conserved role in the timing of formation and the size and shape of the developing otolith.
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Affiliation(s)
- Inna Hughes
- Department of Molecular Biology and Pharmacology, Washington University Medical School, St. Louis, MO 63110, United States
| | - Brian Blasiole
- Department of Pharmacology, Pennsylvania State University College of Medicine, Hershey, PA 17033, United States
| | - David Huss
- Department of Anatomy and Neurobiology, Washington University Medical School, St. Louis, MO 63110, United States
| | - Mark E. Warchol
- Department of Otolaryngology, Washington University Medical School, St. Louis, MO 63110, United States
| | - Nigam P. Rath
- Department of Chemistry and Biochemistry, University of Missouri, St. Louis, MO 63110, United States
| | - Belen Hurle
- National Institutes of Health, National Human Genome Research Institute, Bethesda, MD 20892−2152, United States
| | - Elena Ignatova
- Department of Otolaryngology, Washington University Medical School, St. Louis, MO 63110, United States
| | - J. David Dickman
- Department of Anatomy and Neurobiology, Washington University Medical School, St. Louis, MO 63110, United States
| | - Ruediger Thalmann
- Department of Otolaryngology, Washington University Medical School, St. Louis, MO 63110, United States
| | - Robert Levenson
- Department of Pharmacology, Pennsylvania State University College of Medicine, Hershey, PA 17033, United States
| | - David M. Ornitz
- Department of Molecular Biology and Pharmacology, Washington University Medical School, St. Louis, MO 63110, United States
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47
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Söllner C, Schwarz H, Geisler R, Nicolson T. Mutated otopetrin 1 affects the genesis of otoliths and the localization of Starmaker in zebrafish. Dev Genes Evol 2004; 214:582-90. [PMID: 15480759 DOI: 10.1007/s00427-004-0440-2] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2004] [Accepted: 09/10/2004] [Indexed: 10/26/2022]
Abstract
Otoliths in bony fishes and otoconia in mammals are composite crystals consisting of calcium carbonate and proteins. These biominerals are part of the gravity and linear acceleration detection system of the inner ear. Mutations in otopetrin 1 have been shown to result in lack of otoconia in tilted and mergulhador mutant mice. The molecular function of Otopetrin 1, a novel protein that contains ten predicted transmembrane domains, however, has remained elusive. Here we show that a mutation in the orthologous gene in zebrafish is responsible for the complete absence of otoliths in backstroke mutants. We examined the localization of Starmaker, a secreted protein that is highly abundant in otoliths in backstroke mutants. Starmaker protein accumulated within cells of the otic epithelium, indicating a possible defect in secretion. Our data suggest that Otopetrin 1 in zebrafish may be involved in the protein trafficking of components required for formation of biominerals in the ear.
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Affiliation(s)
- Christian Söllner
- Max Planck Institut für Entwicklungsbiologie, Spemannstrasse 35, 72076, Tübingen, Germany
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Matsui JI, Cotanche DA. Sensory hair cell death and regeneration: two halves of the same equation. Curr Opin Otolaryngol Head Neck Surg 2004; 12:418-25. [PMID: 15377955 DOI: 10.1097/01.moo.0000136873.56878.56] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
PURPOSE OF REVIEW Sensory hair cells are susceptible to ototoxic damage from a variety of sources, including antibiotic treatment. Unfortunately, this often results in permanent hearing and/or balance problems in humans. By understanding how sensory hair cells die in response to aminoglycoside treatment, preventive strategies may be developed. This review will discuss some of the key recent findings in sensory hair cell death and regeneration. RECENT FINDINGS Aminoglycosides induce hair cell death through the initiation of apoptosis. Early and late stages of hair cell apoptosis have been defined, and several of the key molecules involved in the cascade have been identified. Moreover, specific inhibitors of apoptosis rescue hair cells from death and preserve function. Hair cell death has been shown to induce regeneration through supporting cell transdifferentiation, proliferation, and new hair cell differentiation in birds and lower vertebrates. Regeneration in the mammalian cochlea does not occur spontaneously, but genetic manipulation of cell cycle genes, induction of new hair cells through gene therapy, and introduction of stem cells into damaged cochleas suggest that repair and replacement of lost hair cells in the organ of Corti may be possible. Finally, continuing investigations of the mouse, zebrafish, and human genomes may one day enable manipulation of the cochlea so that functional regeneration is readily available as a therapeutic intervention. SUMMARY The discovery that hair cells can regenerate in birds and other nonmammalian vertebrates has fueled a wide range of studies to find ways to restore hearing and balance in mammals. The demonstration that apoptosis and proliferation are coupled as controlling factors in regeneration and the advent of new approaches such as gene therapy, stem cell transplantation, and genomics may lead to methods for inducing hair cell regeneration and repair in the mammalian cochlear and vestibular systems.
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Affiliation(s)
- Jonathan Isamu Matsui
- Laboratory for Cellular and Molecular Hearing Research, Department of Otolaryngology, Children's Hospital, 300 Longwood Avenue, Boston, MA 02115, USA.
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49
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Abstract
Zebrafish have emerged as a useful vertebrate model system in which unbiased large-scale screens have revealed hundreds of mutations affecting vertebrate development. Many zebrafish mutants closely resemble known human disorders, thus providing intriguing prospects for uncovering the genetic basis of human diseases and for the development of pharmacologic agents that inhibit or correct the progression of developmental disorders. The rapid pace of advances in genomic sequencing and map construction, in addition to morpholino targeting and transgenic techniques, have facilitated the identification and analysis of genes associated with zebrafish mutants, thus promoting the development of zebrafish as a model for human disorders. This review aims to illustrate how the zebrafish has been used to identify unknown genes, to assign function to known genes, and to delineate genetic pathways, all contributing valuable leads toward understanding human pathophysiology.
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Affiliation(s)
- Trista E North
- Division of Hematology/Oncology, Department of Medicine, Children's Hospital of Boston, Enders Research Building, Boston, Massachusetts 02115, USA
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50
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Blasiole B, Degrave A, Canfield V, Boehmler W, Thisse C, Thisse B, Mohideen MAPK, Levenson R. Differential expression of Na,K-ATPase alpha and beta subunit genes in the developing zebrafish inner ear. Dev Dyn 2004; 228:386-92. [PMID: 14579377 DOI: 10.1002/dvdy.10391] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
We have used whole-mount in situ hybridization to analyze Na,K-ATPase alpha and beta subunit gene expression in the developing zebrafish ear. Four alpha1-like (alpha1a.1, alpha1a.2, alpha1a.4, and alpha1a.5) and two beta (beta1a and beta2b) subunit genes are expressed in ear beginning at mid-somitogenesis. Each gene exhibits a distinct spatial and temporal expression pattern. The alpha1a.1 gene was ubiquitously expressed in the otic epithelium from mid-somitogenesis to 24 hr postfertilization (hpf). Expression of this gene was gradually reduced and by 48 hpf, alpha1a.1 transcripts were no longer detectable in the ear. The alpha1a.2 and alpha1a.5 genes were expressed in regions that correspond to the anterior macula, lateral crista, and semicircular canal projections up to 48 hpf. At later stages, expression of these genes was limited to cells in the dorsolateral septum and semicircular canal projections. alpha1a.4 and beta1a transcripts were ubiquitously expressed during ear development and were present in most otic tissues at 5 days postfertilization (dpf). Expression of the beta2b gene, on the other hand, was restricted to subsets of cells that form sensory epithelia. These results strongly suggest different functional roles for individual Na,K-ATPase genes in zebrafish ear development. Na,K-ATPase genes are likely to represent useful markers for the analysis of zebrafish otogenesis.
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Affiliation(s)
- Brian Blasiole
- Department of Pharmacology, Penn State College of Medicine, Hershey, Pennsylvania 17033, USA
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