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Trautmann G, Block K, Gutsmann M, Besnard S, Furlan S, Denise P, Volpe P, Blottner D, Salanova M. Increased Homer Activity and NMJ Localization in the Vestibular Lesion het-/- Mouse soleus Muscle. Int J Mol Sci 2024; 25:8577. [PMID: 39201265 PMCID: PMC11354602 DOI: 10.3390/ijms25168577] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2024] [Revised: 07/27/2024] [Accepted: 08/02/2024] [Indexed: 09/02/2024] Open
Abstract
We investigated the shuttling of Homer protein isoforms identified in soluble (cytosolic) vs. insoluble (membrane-cytoskeletal) fraction and Homer protein-protein interaction/activation in the deep postural calf soleus (SOL) and non-postural gastrocnemius (GAS) muscles of het-/- mice, i.e., mice with an autosomal recessive variant responsible for a vestibular disorder, in order to further elucidate a) the underlying mechanisms of disrupted vestibular system-derived modulation on skeletal muscle, and b) molecular signaling at respective neuromuscular synapses. Heterozygote mice muscles served as the control (CTR). An increase in Homer cross-linking capacity was present in the SOL muscle of het-/- mice as a compensatory mechanism for the altered vestibule system function. Indeed, in both fractions, different Homer immunoreactive bands were detectable, as were Homer monomers (~43-48 kDa), Homer dimers (~100 kDa), and several other Homer multimer bands (>150 kDA). The het-/- GAS particulate fraction showed no Homer dimers vs. SOL. The het-/- SOL soluble fraction showed a twofold increase (+117%, p ≤ 0.0004) in Homer dimers and multimers. Homer monomers were completely absent from the SOL independent of the animals studied, suggesting muscle-specific changes in Homer monomer vs. dimer expression in the postural SOL vs. the non-postural GAS muscles. A morphological assessment showed an increase (+14%, p ≤ 0.0001) in slow/type-I myofiber cross-sectional area in the SOL of het-/- vs. CTR mice. Homer subcellular immuno-localization at the neuromuscular junction (NMJ) showed an altered expression in the SOL of het-/-mice, whereas only not-significant changes were found for all Homer isoforms, as judged by RT-qPCR analysis. Thus, muscle-specific changes, myofiber properties, and neuromuscular signaling mechanisms share causal relationships, as highlighted by the variable subcellular Homer isoform expression at the instable NMJs of vestibular lesioned het-/- mice.
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Affiliation(s)
- Gabor Trautmann
- Institute of Integrative Neuroanatomy, Neuromuscular Signaling and System, Charité—Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Philippstrasse 12, 10115 Berlin, Germany; (G.T.); (K.B.); (M.G.); (D.B.)
- Center of Space Medicine Berlin, 10115 Berlin, Germany
| | - Katharina Block
- Institute of Integrative Neuroanatomy, Neuromuscular Signaling and System, Charité—Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Philippstrasse 12, 10115 Berlin, Germany; (G.T.); (K.B.); (M.G.); (D.B.)
- Center of Space Medicine Berlin, 10115 Berlin, Germany
| | - Martina Gutsmann
- Institute of Integrative Neuroanatomy, Neuromuscular Signaling and System, Charité—Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Philippstrasse 12, 10115 Berlin, Germany; (G.T.); (K.B.); (M.G.); (D.B.)
| | - Stéphane Besnard
- UR VERTEX 7480, CHU de Caen, Université de Caen Normandie, 10115 Caen, France;
| | - Sandra Furlan
- C.N.R. Institute of Neuroscience, 14000 Padova, Italy;
| | - Pierre Denise
- COMETE U1075, INSERM, CYCERON, CHU de Caen, Normandie Université, Université de Caen Normandie, 10115 Caen, France;
| | - Pompeo Volpe
- Department of Biomedical Sciences, University of Padova, 14000 Padova, Italy;
| | - Dieter Blottner
- Institute of Integrative Neuroanatomy, Neuromuscular Signaling and System, Charité—Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Philippstrasse 12, 10115 Berlin, Germany; (G.T.); (K.B.); (M.G.); (D.B.)
- Center of Space Medicine Berlin, 10115 Berlin, Germany
| | - Michele Salanova
- Institute of Integrative Neuroanatomy, Neuromuscular Signaling and System, Charité—Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Philippstrasse 12, 10115 Berlin, Germany; (G.T.); (K.B.); (M.G.); (D.B.)
- Center of Space Medicine Berlin, 10115 Berlin, Germany
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Herb M. NADPH Oxidase 3: Beyond the Inner Ear. Antioxidants (Basel) 2024; 13:219. [PMID: 38397817 PMCID: PMC10886416 DOI: 10.3390/antiox13020219] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2024] [Revised: 02/02/2024] [Accepted: 02/06/2024] [Indexed: 02/25/2024] Open
Abstract
Reactive oxygen species (ROS) were formerly known as mere byproducts of metabolism with damaging effects on cellular structures. The discovery and description of NADPH oxidases (Nox) as a whole enzyme family that only produce this harmful group of molecules was surprising. After intensive research, seven Nox isoforms were discovered, described and extensively studied. Among them, the NADPH oxidase 3 is the perhaps most underrated Nox isoform, since it was firstly discovered in the inner ear. This stigma of Nox3 as "being only expressed in the inner ear" was also used by me several times. Therefore, the question arose whether this sentence is still valid or even usable. To this end, this review solely focuses on Nox3 and summarizes its discovery, the structural components, the activating and regulating factors, the expression in cells, tissues and organs, as well as the beneficial and detrimental effects of Nox3-mediated ROS production on body functions. Furthermore, the involvement of Nox3-derived ROS in diseases progression and, accordingly, as a potential target for disease treatment, will be discussed.
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Affiliation(s)
- Marc Herb
- Institute for Medical Microbiology, Immunology and Hygiene, Faculty of Medicine, University Hospital Cologne, University of Cologne, 50935 Cologne, Germany;
- German Centre for Infection Research, Partner Site Bonn-Cologne, 50931 Cologne, Germany
- Cologne Cluster of Excellence on Cellular Stress Responses in Aging-Associated Diseases (CECAD), 50931 Cologne, Germany
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Cote JM, Hood A, Kwon B, Smith JC, Houpt TA. Behavioral and neural responses to high-strength magnetic fields are reduced in otolith mutant mice. Am J Physiol Regul Integr Comp Physiol 2023; 325:R181-R192. [PMID: 37306398 PMCID: PMC10393321 DOI: 10.1152/ajpregu.00317.2022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2022] [Revised: 06/06/2023] [Accepted: 06/06/2023] [Indexed: 06/13/2023]
Abstract
Static high magnetic fields (MFs) interact with the vestibular system of humans and rodents. In rats and mice, exposure to MFs causes perturbations such as head movements, circular locomotion, suppressed rearing, nystagmus, and conditioned taste aversion acquisition. To test the role of otoconia, two mutant mouse models were examined, head-tilt Nox3het (het) and tilted Otop1 (tlt), with mutations, respectively, in Nox3, encoding the NADPH oxidase 3 enzyme, and Otop1, encoding the otopetrin 1 proton channel, which are normally expressed in the otolith organs, and are critical for otoconia formation. Consequently, both mutants show a near complete loss of otoconia in the utricle and saccule, and are nonresponsive to linear acceleration. Mice were exposed to a 14.1 Tesla MF for 30 min. After exposure, locomotor activity, conditioned taste aversion and c-Fos (in het) were assessed. Wild-type mice exposed to the MF showed suppressed rearing, increased latency to rear, locomotor circling, and c-Fos in brainstem nuclei related to vestibular processing (prepositus, spinal vestibular, and supragenual nuclei). Mutant het mice showed no response to the magnet and were similar to sham animals in all assays. Unlike het, tlt mutants exposed to the MF showed significant locomotor circling and suppressed rearing compared with sham controls, although they failed to acquire a taste aversion. The residual responsiveness of tlt versus het mice might reflect a greater semicircular deficit in het mice. These results demonstrate the necessity of the otoconia for the full effect of exposure to high MFs, but also suggest a semicircular contribution.
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Affiliation(s)
- Jason M Cote
- Department of Biological Science, Florida State University, Tallahassee, Florida, United States
| | - Alison Hood
- Department of Biological Science, Florida State University, Tallahassee, Florida, United States
| | - Bumsup Kwon
- Department of Biological Science, Florida State University, Tallahassee, Florida, United States
| | - James C Smith
- Department of Psychology, Florida State University, Tallahassee, Florida, United States
| | - Thomas A Houpt
- Department of Biological Science, Florida State University, Tallahassee, Florida, United States
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Song JHT, Grant RL, Behrens VC, Kučka M, Roberts Kingman GA, Soltys V, Chan YF, Kingsley DM. Genetic studies of human-chimpanzee divergence using stem cell fusions. Proc Natl Acad Sci U S A 2021; 118:e2117557118. [PMID: 34921118 PMCID: PMC8713981 DOI: 10.1073/pnas.2117557118] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/10/2021] [Indexed: 12/17/2022] Open
Abstract
Complete genome sequencing has identified millions of DNA changes that differ between humans and chimpanzees. Although a subset of these changes likely underlies important phenotypic differences between humans and chimpanzees, it is currently difficult to distinguish causal from incidental changes and to map specific phenotypes to particular genome locations. To facilitate further genetic study of human-chimpanzee divergence, we have generated human and chimpanzee autotetraploids and allotetraploids by fusing induced pluripotent stem cells (iPSCs) of each species. The resulting tetraploid iPSCs can be stably maintained and retain the ability to differentiate along ectoderm, mesoderm, and endoderm lineages. RNA sequencing identifies thousands of genes whose expression differs between humans and chimpanzees when assessed in single-species diploid or autotetraploid iPSCs. Analysis of gene expression patterns in interspecific allotetraploid iPSCs shows that human-chimpanzee expression differences arise from substantial contributions of both cis-acting changes linked to the genes themselves and trans-acting changes elsewhere in the genome. To enable further genetic mapping of species differences, we tested chemical treatments for stimulating genome-wide mitotic recombination between human and chimpanzee chromosomes, and CRISPR methods for inducing species-specific changes on particular chromosomes in allotetraploid cells. We successfully generated derivative cells with nested deletions or interspecific recombination on the X chromosome. These studies confirm an important role for the X chromosome in trans regulation of expression differences between species and illustrate the potential of this system for more detailed cis and trans mapping of the molecular basis of human and chimpanzee evolution.
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Affiliation(s)
- Janet H T Song
- Department of Developmental Biology, Stanford University School of Medicine, Stanford, CA 94305
- Department of Genetics, Stanford University School of Medicine, Stanford, CA 94305
| | - Rachel L Grant
- Department of Developmental Biology, Stanford University School of Medicine, Stanford, CA 94305
| | - Veronica C Behrens
- Department of Developmental Biology, Stanford University School of Medicine, Stanford, CA 94305
| | - Marek Kučka
- Friedrich Miescher Laboratory of the Max Planck Society, 72076 Tübingen, Germany
| | | | - Volker Soltys
- Friedrich Miescher Laboratory of the Max Planck Society, 72076 Tübingen, Germany
| | - Yingguang Frank Chan
- Friedrich Miescher Laboratory of the Max Planck Society, 72076 Tübingen, Germany
| | - David M Kingsley
- Department of Developmental Biology, Stanford University School of Medicine, Stanford, CA 94305;
- HHMI, Stanford University School of Medicine, Stanford, CA 94305
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Neural Interruption by Unilateral Labyrinthectomy Biases the Directional Preference of Otolith-Related Vestibular Neurons. Brain Sci 2021; 11:brainsci11080987. [PMID: 34439606 PMCID: PMC8393366 DOI: 10.3390/brainsci11080987] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2021] [Revised: 07/13/2021] [Accepted: 07/22/2021] [Indexed: 11/17/2022] Open
Abstract
Background: The directional preference of otolith-related vestibular neurons elucidates the neuroanatomical link of labyrinths, but few direct experimental data have been provided. Methods: The directional preference of otolith-related vestibular neurons was measured in the vestibular nucleus using chemically induced unilateral labyrinthectomy (UL). For the model evaluation, static and dynamic behavioral tests as well as a histological test were performed. Extracellular neural activity was recorded for the neuronal responses to the horizontal head rotation and the linear head translation. Results: Seventy-seven neuronal activities were recorded, and the total population was divided into three groups: left UL (20), sham (35), and right UL (22). Based on directional preference, two sub-groups were again classified as contra- and ipsi-preferred neurons. There was no significance in the number of those sub-groups (contra-, 15/35, 43%; ipsi-, 20/35, 57%) in the sham (p = 0.155). However, more ipsi-preferred neurons (19/22, 86%) were observed after right UL (p = 6.056 × 10−5), while left UL caused more contra-preferred neurons (13/20, 65%) (p = 0.058). In particular, the convergent neurons mainly led this biased difference (ipsi-, 100% after right UL and contra-, 89% after left UL) (p < 0.002). Conclusions: The directional preference of the neurons depended on the side of the lesion, and its dominance was mainly led by the convergent neurons.
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Mouse Magnetic-field Nystagmus in Strong Static Magnetic Fields Is Dependent on the Presence of Nox3. Otol Neurotol 2019; 39:e1150-e1159. [PMID: 30444848 DOI: 10.1097/mao.0000000000002024] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
HYPOTHESIS Magnetic vestibular stimulation (MVS) elicits nystagmus in C57BL/6J mice but not head tilt mice lacking Nox3, which is required for normal otoconial development. BACKGROUND Humans have vertigo and nystagmus in strong magnetic fields within magnetic resonance imaging machines. The hypothesized mechanism is a Lorentz force driven by electrical current entering the utricular neuroepithelium, acting indirectly on crista hair cells via endolymph movement deflecting cupulae. We tested an alternate hypothesized mechanism: Lorentz action directly on crista hair cell stereocilia, driven by their currents independent of the utricle. METHODS Before MVS, vestibulo-ocular reflex responses of eight C57BL/6J mice and six head tilt mice were measured during whole-body sinusoidal rotations and tilts using video-oculography. Mice were then placed within a 4.7 Tesla magnetic field with the horizontal semicircular canals approximately Earth-horizontal for ≥1 minute in several head orientations, while eye movements were recorded via infrared video in darkness. RESULTS Outside the magnet, both C57BL/6J and head tilt mice had intact horizontal vestibulo-ocular reflex, but only C57BL/6J mice exhibited static counter-roll responses to tilt (normal utiruclo-ocular reflex). When placed in the magnet nose-first, C57BL/6J mice had left-beating nystagmus, lasting a median of 32.8 seconds. When tail-first, nystagmus was right-beating and similar duration (median 28.0 s, p > 0.05). In contrast, head tilt mice lacked magnetic field-induced nystagmus (p < 0.001). CONCLUSIONS C57BL/6J mice generate nystagmus in response to MVS, while mice deficient in Nox3 do not. This suggests 1) a normal utricle is necessary, and 2) functioning semicircular canals are insufficient, to generate MVS-induced nystagmus in mice.
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Smith PF. The Growing Evidence for the Importance of the Otoliths in Spatial Memory. Front Neural Circuits 2019; 13:66. [PMID: 31680880 PMCID: PMC6813194 DOI: 10.3389/fncir.2019.00066] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2019] [Accepted: 09/30/2019] [Indexed: 01/14/2023] Open
Abstract
Many studies have demonstrated that vestibular sensory input is important for spatial learning and memory. However, it has been unclear what contributions the different parts of the vestibular system - the semi-circular canals and otoliths - make to these processes. The advent of mutant otolith-deficient mice has made it possible to isolate the relative contributions of the otoliths, the utricle and saccule. A number of studies have now indicated that the loss of otolithic function impairs normal spatial memory and also impairs the normal function of head direction cells in the thalamus and place cells in the hippocampus. Epidemiological studies have also provided evidence that spatial memory impairment with aging, may be linked to saccular function. The otoliths may be important in spatial cognition because of their evolutionary age as a sensory detector of orientation and the fact that velocity storage is important to the way that the brain encodes its place in space.
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Affiliation(s)
- Paul F. Smith
- Department of Pharmacology and Toxicology, Brain Health Research Centre, School of Biomedical Sciences, University of Otago Medical School, Dunedin, New Zealand
- Brain Research New Zealand, Auckland, New Zealand
- Eisdell Moore Centre for Hearing and Balance Research, University of Auckland, Auckland, New Zealand
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Le Gall A, Hilber P, Chesneau C, Bulla J, Toulouse J, Machado M, Philoxene B, Smith P, Besnard S. The critical role of vestibular graviception during cognitive-motor development. Behav Brain Res 2019; 372:112040. [DOI: 10.1016/j.bbr.2019.112040] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2019] [Revised: 06/13/2019] [Accepted: 06/14/2019] [Indexed: 01/07/2023]
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Hilber P, Cendelin J, Le Gall A, Machado ML, Tuma J, Besnard S. Cooperation of the vestibular and cerebellar networks in anxiety disorders and depression. Prog Neuropsychopharmacol Biol Psychiatry 2019; 89:310-321. [PMID: 30292730 DOI: 10.1016/j.pnpbp.2018.10.004] [Citation(s) in RCA: 44] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/04/2018] [Revised: 09/25/2018] [Accepted: 10/04/2018] [Indexed: 12/28/2022]
Abstract
The discipline of affective neuroscience is concerned with the neural bases of emotion and mood. The past decades have witnessed an explosion of research in affective neuroscience, increasing our knowledge of the brain areas involved in fear and anxiety. Besides the brain areas that are classically associated with emotional reactivity, accumulating evidence indicates that both the vestibular and cerebellar systems are involved not only in motor coordination but also influence both cognition and emotional regulation in humans and animal models. The cerebellar and the vestibular systems show the reciprocal connection with a myriad of anxiety and fear brain areas. Perception anticipation and action are also major centers of interest in cognitive neurosciences. The cerebellum is crucial for the development of an internal model of action and the vestibular system is relevant for perception, gravity-related balance, navigation and motor decision-making. Furthermore, there are close relationships between these two systems. With regard to the cooperation between the vestibular and cerebellar systems for the elaboration and the coordination of emotional cognitive and visceral responses, we propose that altering the function of one of the systems could provoke internal model disturbances and, as a result, anxiety disorders followed potentially with depressive states.
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Affiliation(s)
- Pascal Hilber
- Centre de Recherche sur les Fonctionnements et Dysfonctionnements Psychologigues, CRFDP EA 7475, Rouen Normandie University, Bat Blondel, Place E. Blondel 76821, Mont Saint Aignan cedex, France.
| | - Jan Cendelin
- Department of Pathophysiology, Faculty of Medicine in Pilsen, Charles University, alej Svobody 1655/76, 323 00 Plzen, Czech Republic; Laboratory of Neurodegenerative Disorders, Biomedical Center, Faculty of Medicine in Pilsen, Charles University, alej Svobody 1655/76, 323 00 Plzen, Czech Republic
| | - Anne Le Gall
- UMR UCBN/INSERM U 1075 COMETE, Pole des Formations et de Recherche en Sante, Normandie University, 2 Rue Rochambelles, 14032 Caen, cedex 5, France
| | - Marie-Laure Machado
- UMR UCBN/INSERM U 1075 COMETE, Pole des Formations et de Recherche en Sante, Normandie University, 2 Rue Rochambelles, 14032 Caen, cedex 5, France
| | - Jan Tuma
- Department of Pathophysiology, Faculty of Medicine in Pilsen, Charles University, alej Svobody 1655/76, 323 00 Plzen, Czech Republic; Laboratory of Neurodegenerative Disorders, Biomedical Center, Faculty of Medicine in Pilsen, Charles University, alej Svobody 1655/76, 323 00 Plzen, Czech Republic
| | - Stephane Besnard
- UMR UCBN/INSERM U 1075 COMETE, Pole des Formations et de Recherche en Sante, Normandie University, 2 Rue Rochambelles, 14032 Caen, cedex 5, France
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Fuller PM, Fuller CA. Genetic Evidence for a Neurovestibular Influence on the Mammalian Circadian Pacemaker. J Biol Rhythms 2016; 21:177-84. [PMID: 16731657 DOI: 10.1177/0748730406288148] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The mammalian circadian timing system (CTS) exerts endogenous temporal control over virtually every biochemical, physiological, and neurobiological process. Recent studies have suggested an interrelationship between the neurovestibular system, specifically the macular otoconial gravity receptors, and the CTS. To test for a functional relationship between these 2 seemingly disparate neuronal systems, the authors performed a study to evaluate the influence of the vestibular system on 3 fundamental properties of the CTS: entrainment, photic modulation, and period. The present study used a nonrecombinant mutant mouse, the head-tilt mouse (abbr. het), which lacks otoconia and hence gravity reception, to evaluate CTS function in mice lacking vestibular inputs. Circadian rhythms of body temperature (Tb) and locomotor activity (ACT) were recorded continuously by biotelemetry in het mice as well as wild-type (PWT) controls during exposure to 4 photic regimens: 12:12 LD, DD (0 μmoles s-1m-2), constant bright light (LLB; 0.5 μmoles s-1m-2), and constant dim light (LLD; 0.02 μmoles s-1m-2). In DD, the circadian period of the Tband ACT rhythms was significantly longer ( p < 0.001) in het than in PWT mice. In addition, the circadian period of Tband ACT was significantly longer ( p < 0.01) in LLBthan in DD for both the het and PWT groups, although increasing ambient illuminance (i.e., DD to LLB) had a significantly greater ( p < 0.01) period-lengthening effect in the PWT group than in the het group. The results of the present study demonstrate for the first time that the vestibular macular gravity receptors influence 2 fundamental properties of the mammalian CTS: (1) the intrinsic circadian pacemaker period and (2) the period-altering response to changes in tonic light intensity. The results of the present study thus provide the first neurobehavioral evidence for a vestibular-circadian interrelationship as well as suggest a novel mechanism underlying the signaling of activity-based nonphotic stimuli to the CTS.
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Affiliation(s)
- Patrick M Fuller
- Section of Neurobiology, Physiology & Behavior, University of California, Davis, CA 95616-8519, USA
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Vijayakumar S, Lever TE, Pierce J, Zhao X, Bergstrom D, Lundberg YW, Jones TA, Jones SM. Vestibular dysfunction, altered macular structure and trait localization in A/J inbred mice. Mamm Genome 2015; 26:154-72. [PMID: 25645995 DOI: 10.1007/s00335-015-9556-0] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2014] [Accepted: 01/13/2015] [Indexed: 11/30/2022]
Abstract
A/J mice develop progressive hearing loss that begins before 1 month of age and is attributed to cochlear hair cell degeneration. Screening tests indicated that this strain also develops early onset vestibular dysfunction and has otoconial deficits. The purpose of this study was to characterize the vestibular dysfunction and macular structural pathology over the lifespan of A/J mice. Vestibular function was measured using linear vestibular evoked potentials (VsEPs). Macular structural pathology was evaluated using light microscopy, scanning electron microscopy, transmission electron microscopy, confocal microscopy and Western blotting. Individually, vestibular functional deficits in mice ranged from mild to profound. On average, A/J mice had significantly reduced vestibular sensitivity (elevated VsEP response thresholds and smaller amplitudes), whereas VsEP onset latency was prolonged compared to age-matched controls (C57BL/6). A limited age-related vestibular functional loss was also present. Structural analysis identified marked age-independent otoconial abnormalities in concert with some stereociliary bundle defects. Macular epithelia were incompletely covered by otoconial membranes with significantly reduced opacity and often contained abnormally large or giant otoconia as well as normal-appearing otoconia. Elevated expression of key otoconins (i.e., otoconin 90, otolin and keratin sulfate proteoglycan) ruled out the possibility of reduced levels contributing to otoconial dysgenesis. The phenotype of A/J was partially replicated in a consomic mouse strain (C57BL/6J-Chr 17(A/J)/NaJ), thus indicating that Chr 17(A/J) contained a trait locus for a new gene variant responsible to some extent for the A/J vestibular phenotype. Quantitative trait locus analysis identified additional epistatic influences associated with chromosomes 1, 4, 9 and X. Results indicate that the A/J phenotype represents a complex trait, and the A/J mouse strain presents a new model for the study of mechanisms underlying otoconial formation and maintenance.
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Affiliation(s)
- Sarath Vijayakumar
- Department of Special Education and Communication Disorders, University of Nebraska-Lincoln, 301 Barkley Memorial Center, Lincoln, NE, 68583, USA
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Jones SM, Jones TA. Genetics of peripheral vestibular dysfunction: lessons from mutant mouse strains. J Am Acad Audiol 2014; 25:289-301. [PMID: 25032973 PMCID: PMC4310552 DOI: 10.3766/jaaa.25.3.8] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
BACKGROUND A considerable amount of research has been published about genetic hearing impairment. Fifty to sixty percent of hearing loss is thought to have a genetic cause. Genes may also play a significant role in acquired hearing loss due to aging, noise exposure, or ototoxic medications. Between 1995 and 2012, over 100 causative genes have been identified for syndromic and nonsyndromic forms of hereditary hearing loss. Mouse models have been extremely valuable in facilitating the discovery of hearing loss genes and in understanding inner ear pathology due to genetic mutations or elucidating fundamental mechanisms of inner ear development. PURPOSE Whereas much is being learned about hereditary hearing loss and the genetics of cochlear disorders, relatively little is known about the role genes may play in peripheral vestibular impairment. Here we review the literature with regard to genetics of vestibular dysfunction and discuss what we have learned from studies using mutant mouse models and direct measures of peripheral vestibular neural function. RESULTS Several genes are considered that when mutated lead to varying degrees of inner ear vestibular dysfunction due to deficits in otoconia, stereocilia, hair cells, or neurons. Behavior often does not reveal the inner ear deficit. Many of the examples presented are also known to cause human disorders. CONCLUSIONS Knowledge regarding the roles of particular genes in the operation of the vestibular sensory apparatus is growing, and it is clear that gene products co-expressed in the cochlea and vestibule may play different roles in the respective end organs. The discovery of new genes mediating critical inner ear vestibular function carries the promise of new strategies in diagnosing, treating, and managing patients as well as predicting the course and level of morbidity in human vestibular disease.
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Affiliation(s)
- Sherri M Jones
- Department of Special Education and Communication Disorders, University of Nebraska-Lincoln
| | - Timothy A Jones
- Department of Special Education and Communication Disorders, University of Nebraska-Lincoln
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Beraneck M, Bojados M, Le Séac'h A, Jamon M, Vidal PP. Ontogeny of mouse vestibulo-ocular reflex following genetic or environmental alteration of gravity sensing. PLoS One 2012; 7:e40414. [PMID: 22808156 PMCID: PMC3393735 DOI: 10.1371/journal.pone.0040414] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2012] [Accepted: 06/07/2012] [Indexed: 11/28/2022] Open
Abstract
The vestibular organs consist of complementary sensors: the semicircular canals detect rotations while the otoliths detect linear accelerations, including the constant pull of gravity. Several fundamental questions remain on how the vestibular system would develop and/or adapt to prolonged changes in gravity such as during long-term space journey. How do vestibular reflexes develop if the appropriate assembly of otoliths and semi-circular canals is perturbed? The aim of present work was to evaluate the role of gravity sensing during ontogeny of the vestibular system. In otoconia-deficient mice (ied), gravity cannot be sensed and therefore maculo-ocular reflexes (MOR) were absent. While canals-related reflexes were present, the ied deficit also led to the abnormal spatial tuning of the horizontal angular canal-related VOR. To identify putative otolith-related critical periods, normal C57Bl/6J mice were subjected to 2G hypergravity by chronic centrifugation during different periods of development or adulthood (Adult-HG) and compared to non-centrifuged (control) C57Bl/6J mice. Mice exposed to hypergravity during development had completely normal vestibulo-ocular reflexes 6 months after end of centrifugation. Adult-HG mice all displayed major abnormalities in maculo-ocular reflexe one month after return to normal gravity. During the next 5 months, adaptation to normal gravity occurred in half of the individuals. In summary, genetic suppression of gravity sensing indicated that otolith-related signals might be necessary to ensure proper functioning of canal-related vestibular reflexes. On the other hand, exposure to hypergravity during development was not sufficient to modify durably motor behaviour. Hence, 2G centrifugation during development revealed no otolith-specific critical period.
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Affiliation(s)
- Mathieu Beraneck
- CNRS UMR 8194, Université Paris Descartes, Sorbonne Paris Cité, Paris, France.
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14
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Machado ML, Kroichvili N, Freret T, Philoxène B, Lelong-Boulouard V, Denise P, Besnard S. Spatial and non-spatial performance in mutant mice devoid of otoliths. Neurosci Lett 2012; 522:57-61. [PMID: 22705908 DOI: 10.1016/j.neulet.2012.06.016] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2012] [Revised: 06/01/2012] [Accepted: 06/05/2012] [Indexed: 11/17/2022]
Abstract
Vestibular deafferentation induces strong spatial memory impairments in rodents and dorsal hippocampal atrophy in humans, suggesting that vestibular information plays an important role in spatial-memory processes. However, previous studies have not discriminated between the role of the semi-circular canals, gravisensors and cochlear sense organ in such impairments due to complete damage of the vestibular and cochlear organs in their models of lesions. This is the first time that mutant mice (het/het) devoid of otoconia (lack of vestibular gravisensors) have been evaluated in behavioral tests. Results show different levels of achievement in the tests. The rotarod and elevated plus-maze were not executable, the rotarod being a safer test for differentiating the het/het mouse phenotype compared to the more anxiogenic swimming pool. Y-maze and place recognition tests were achieved, but chance values were not reached in the het/het group. Additionally, het/het mice presented uncommon behavior when faced with objects during the object recognition test. Impairments in het/het mice in the Y-maze test suggest a crucial role of the vestibular gravisensors in spatial-memory processes.
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Affiliation(s)
- M L Machado
- Université de Caen Basse-Normandie, U 1075 COMETE, Caen 14032, France.
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15
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Kaneko CRS, Rosenfeld S, Fontaine E, Markov A, Phillips JO, Yarno J. A preformed scleral search coil for measuring mouse eye movements. J Neurosci Methods 2010; 193:126-31. [PMID: 20817027 DOI: 10.1016/j.jneumeth.2010.08.023] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2010] [Revised: 08/12/2010] [Accepted: 08/24/2010] [Indexed: 10/19/2022]
Abstract
Mice are excellent subjects for use of genetic-manipulation techniques to study the basis of pathological and normal physiology and behavior; however behavioral analyses of associated phenotypes is often limited. To improve the accuracy and specificity of repeated measurements of vestibular function, we developed a miniaturized, contact-lens scleral search coil to measure mouse eye movements. We describe the physical attributes and document its functionality by measuring vestibuloocular responses in normal mice. This coil should greatly improve the sensitivity and documentation of vestibular dysfunction in mouse models of pathology and dysfunction while allowing screening of significant numbers of subjects.
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Affiliation(s)
- Chris R S Kaneko
- Department of Physiology and Biophysics, University of Washington, Seattle, WA 98195, USA.
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16
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Jones TA, Jones SM, Hoffman LF. Resting discharge patterns of macular primary afferents in otoconia-deficient mice. J Assoc Res Otolaryngol 2008; 9:490-505. [PMID: 18661184 DOI: 10.1007/s10162-008-0132-0] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2007] [Accepted: 07/07/2008] [Indexed: 10/21/2022] Open
Abstract
Vestibular primary afferents in the normal mammal are spontaneously active. The consensus hypothesis states that such discharge patterns are independent of stimulation and depend instead on excitation by vestibular hair cells due to background release of synaptic neurotransmitter. In the case of otoconial sensory receptors, it is difficult to test the independence of resting discharge from natural tonic stimulation by gravity. We examined this question by studying discharge patterns of single vestibular primary afferent neurons in the absence of gravity stimulation using two mutant strains of mice that lack otoconia (OTO-; head tilt, het-Nox3, and tilted, tlt-Otop1). Our findings demonstrated that macular primary afferent neurons exhibit robust resting discharge activity in OTO- mice. Spike interval coefficient of variation (CV = SD/mean spike interval) values reflected both regular and irregular discharge patterns in OTO- mice, and the range of values for rate-normalized CV was similar to mice and other mammals with intact otoconia although there were proportionately fewer irregular fibers. Mean discharge rates were slightly higher in otoconia-deficient strains even after accounting for proportionately fewer irregular fibers [OTO- = 75.4 +/- 31.1(113) vs OTO+ = 68.1 +/- 28.5(143) in sp/s]. These results confirm the hypothesis that resting activity in macular primary afferents occurs in the absence of ambient stimulation. The robust discharge rates are interesting in that they may reflect the presence of a functionally 'up-regulated' tonic excitatory process in the absence of natural sensory stimulation.
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Affiliation(s)
- T A Jones
- Communication Sciences and Disorders, School of Allied Health Sciences, East Carolina University, Health Sciences Building, Rm 3310P, Greenville, NC 27858-4353, USA.
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17
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Hoffman LF, Ross MD, Varelas J, Jones SM, Jones TA. Afferent synapses are present in utricular hair cells from otoconia-deficient mice. Hear Res 2006; 222:35-42. [PMID: 17023128 DOI: 10.1016/j.heares.2006.05.013] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/20/2005] [Revised: 05/17/2006] [Accepted: 05/19/2006] [Indexed: 11/23/2022]
Abstract
The head tilt mouse (het/het, abbr. het) is a naturally occurring mutant whose salient phenotypic traits include the complete absence of otoconia in both the utricle and saccule. Cursory histologic evaluation has indicated that the neuroepithelia exhibit a normal appearance. Though evidence exists indicating that utricular function is severely if not completely compromised in these animals, it is not yet known whether afferent synapses exist within utricular hair cells of otoconia-deficient mutants. The absence of synapses would be suggestive of a trophic relationship between stimulus-evoked hair cell activation and the afferent synapse. To address this question, we have conducted an ultrastructural survey of utricular sensory epithelia from confirmed het mice. The specific objective was to determine whether utricular hair cells made synaptic contact with afferent neurons. We found that both type I and II hair cells from utricles of het mice exhibited afferent synapses that were found at numerous sites distributed throughout the utricle. These results indicate that afferent synapses within vestibular hair cells do not critically depend upon stimulus-evoked activity.
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Affiliation(s)
- Larry F Hoffman
- Division of Head and Neck Surgery and Brain Research Institute, Geffen School of Medicine at UCLA, Box 951624, Los Angeles, CA 90095-1624, USA.
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18
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MacLennan AJ, Benner SJ, Andringa A, Chaves AH, Rosing JL, Vesey R, Karpman AM, Cronier SA, Lee N, Erway LC, Miller ML. The S1P2 sphingosine 1-phosphate receptor is essential for auditory and vestibular function. Hear Res 2006; 220:38-48. [PMID: 16945494 DOI: 10.1016/j.heares.2006.06.016] [Citation(s) in RCA: 71] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/22/2005] [Revised: 06/15/2006] [Accepted: 06/23/2006] [Indexed: 11/16/2022]
Abstract
Sphingosine 1-phosphate (S1P) is an endogenous growth factor with potent effects on many different cell types. Most of these effects are produced by activation of one or more of a family of G-protein coupled receptors. The S1P2 receptor can mediate S1P-induced proliferation, differentiation and survival in a wide variety of cells in culture. However, identifying essential in vivo functions for S1P2 has been hampered by its ubiquitous expression and the failure to detect any anatomical abnormalities in initial analyses of S1P2 knockout mice. We report here that all S1P2 knockout mice are profoundly deaf from postnatal day 22 and approximately half display a progressive loss of vestibular function with aging. Anatomically, both the auditory and vestibular systems appear to develop normally but then degrade. Morphological defects associated with hearing are first detected at 3 weeks postnatal as deformations of the organ of Corti/Nuel's space. By one year of age structures within the scala media are dramatically altered. The S1P2 knockout mice also display a loss of otoconia consistent with the vestibular impairment. The present data are the first to indicate that S1P signaling plays critical roles, in vivo, in auditory and vestibular functions. The data further establish that the S1P signaling occurs through the S1P2 receptor and makes an essential contribution to the structural maintenance of these systems, raising the possibility that properly targeted enhancement of this signaling may prove to be clinically beneficial.
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Affiliation(s)
- A John MacLennan
- Department of Molecular and Cellular Physiology, University of Cincinnati, 231 Albert Sabin Way, Room 4155 MSB, Cincinnati, OH 45267-0576, USA
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19
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Beckingham KM, Texada MJ, Baker DA, Munjaal R, Armstrong JD. Genetics of graviperception in animals. ADVANCES IN GENETICS 2006; 55:105-45. [PMID: 16291213 DOI: 10.1016/s0065-2660(05)55004-1] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/10/2023]
Abstract
Gravity is a constant stimulus for life on Earth and most organisms have evolved structures to sense gravitational force and incorporate its influence into their behavioral repertoire. Here we focus attention on animals and their diverse structures for perceiving and responding to the gravitational vector-one of the few static reference stimuli for any mobile organism. We discuss vertebrate, arthropod, and nematode models from the perspective of the role that genetics is playing in our understanding of graviperception in each system. We describe the key sensory structures in each class of organism and present what is known about the genetic control of development of these structures and the molecular signaling pathways operating in the mature organs. We also discuss the role of large genetic screens in identifying specific genes with roles in mechanosensation and graviperception.
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Affiliation(s)
- Kathleen M Beckingham
- Department of Biochemistry and Cell Biology, Rice University, Houston, TX 77005, USA
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20
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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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21
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Jones SM, Jones TA, Johnson KR, Yu H, Erway LC, Zheng QY. A comparison of vestibular and auditory phenotypes in inbred mouse strains. Brain Res 2006; 1091:40-6. [PMID: 16499890 PMCID: PMC2859199 DOI: 10.1016/j.brainres.2006.01.066] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2005] [Revised: 01/12/2006] [Accepted: 01/13/2006] [Indexed: 10/25/2022]
Abstract
The purposes of this research were to quantify gravity receptor function in inbred mouse strains and compare vestibular and auditory function for strain- and age-matched animals. Vestibular evoked potentials (VsEPs) were collected for 19 inbred strains at ages from 35 to 389 days old. On average, C57BL/6J (35 to 190 days), BALB/cByJ, C3H/HeSnJ, CBA/J, and young LP/J mice had VsEP thresholds comparable to normal. Elevated VsEP thresholds were found for elderly C57BL/6J, NOD.NONH2(kb), BUB/BnJ, A/J, DBA/2J, NOD/LtJ, A/WySnJ, MRL/MpJ, A/HeJ, CAST/Ei, SJL/J, elderly LP/J, and CE/J. These results suggest that otolithic function varies among inbred strains and several strains displayed gravity receptor deficits by 90 days old. Auditory brainstem response (ABR) thresholds were compared to VsEP thresholds for 14 age-matched strains. C57BL/6J mice (up to 190 days) showed normal VsEPs with normal to mildly elevated ABR thresholds. Four strains (BUB/BnJ, NOD/LtJ, A/J, elderly LP/J) had significant hearing loss and elevated VsEP thresholds. Four strains (DBA/2J, A/WySnJ, NOD.NONH2(kb), A/HeJ) had elevated VsEP thresholds (including absent VsEPs) with mild to moderate elevations in ABR thresholds. Three strains (MRL/MpJ, Ce/J, SJL/J) had significant vestibular loss with no concomitant hearing loss. These results suggest that functional change in one sensory system does not obligate change in the other. We hypothesize that genes responsible for early onset hearing loss may affect otolithic function, yet the time course of functional change may vary. In addition, some genetic mutations may produce primarily gravity receptor deficits. Potential genes responsible for selective gravity receptor impairment demonstrated herein remain to be identified.
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Affiliation(s)
- Sherri M Jones
- Department of Communication Sciences and Disorders, East Carolina University, Belk Annex, Greenville and Charles Boulevards, Greenville, NC 27858, USA.
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22
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Besson V, Nalesso V, Herpin A, Bizot JC, Messaddeq N, Romand R, Puech A, Blanquet V, Hérault Y. Training and aging modulate the loss-of-balance phenotype observed in a new ENU-induced allele of Otopetrin1. Biol Cell 2005; 97:787-98. [PMID: 15730345 DOI: 10.1042/bc20040525] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
BACKGROUND INFORMATION The sensing of head movement in mammals depends upon the vestibular endorgan of the inner ear, a complex structure made up of the semicircular canals and otoliths. Due to the similarity between the human and mouse vestibular apparatus, the analysis of mutant mouse is a valuable strategy aiming to identify genes involved in the control of balance and movement. RESULTS In the course of a genome-wide chemical-mutagenesis programme, we isolated a recessive mutation, named ied (inner ear defect), which induced a severe loss-of-balance. A detailed phenotypic analysis of the mutant mice demonstrates that the balance impairment does not affect the motor activity and can be rescued, in part, by training, despite a complete agenesis of otoconia in the utricule and the saccule of the inner ear. Molecular characterization of the ied mutation revealed a transversion that affects the splicing of the second exon of the Otopetrin1 gene located on mouse chromosome 5. The consequence of such a mutation leads to a disruption of the transcription of the gene. CONCLUSIONS The identification of the ied knock-down allele strengthens the role of the Otopetrin1 in the sensing of balance. Moreover, the rescue of the ied mutant phenotype in specific behavioural tasks confirmed that other sensory inputs or neural plasticity can compensate, to some extent, for the loss-of-balance. In the future, the ied mutant mice might be helpful to study the genetic control of the compensation strategies developed by organisms to counteract balance defects.
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Affiliation(s)
- Vanessa Besson
- CNRS IEM FRE2815, Institut de Transgénose, 3B rue de la Férollerie, 45071 Orleans cedex 2, France
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23
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Shim K, Minowada G, Coling DE, Martin GR. Sprouty2, a mouse deafness gene, regulates cell fate decisions in the auditory sensory epithelium by antagonizing FGF signaling. Dev Cell 2005; 8:553-64. [PMID: 15809037 DOI: 10.1016/j.devcel.2005.02.009] [Citation(s) in RCA: 203] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2005] [Revised: 02/11/2005] [Accepted: 02/22/2005] [Indexed: 11/20/2022]
Abstract
The auditory sensory epithelium (organ of Corti), where sound waves are converted to electrical signals, comprises a highly ordered array of sensory receptor (hair) cells and nonsensory supporting cells. Here, we report that Sprouty2, which encodes a negative regulator of signaling via receptor tyrosine kinases, is required for normal hearing in mice, and that lack of SPRY2 results in dramatic perturbations in organ of Corti cytoarchitecture: instead of two pillar cells, there are three, resulting in the formation of an ectopic tunnel of Corti. We demonstrate that these effects are due to a postnatal cell fate transformation of a Deiters' cell into a pillar cell. Both this cell fate change and hearing loss can be partially rescued by reducing Fgf8 gene dosage in Spry2 null mutant mice. Our results provide evidence that antagonism of FGF signaling by SPRY2 is essential for establishing the cytoarchitecture of the organ of Corti and for hearing.
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Affiliation(s)
- Katherine Shim
- Department of Anatomy and Program in Developmental Biology, School of Medicine, University of California, San Francisco, California 94143, USA
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24
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Jones SM, Erway LC, Johnson KR, Yu H, Jones TA. Gravity receptor function in mice with graded otoconial deficiencies. Hear Res 2005; 191:34-40. [PMID: 15109702 DOI: 10.1016/j.heares.2004.01.008] [Citation(s) in RCA: 68] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/04/2003] [Accepted: 01/10/2004] [Indexed: 11/19/2022]
Abstract
The purpose of the present study was to examine gravity receptor function in mutant mouse strains with variable deficits in otoconia: lethal milk (lm), pallid (pa), tilted (tlt), mocha (mh), and muted (mu). Control animals were either age-matched heterozygotes or C57BL/6J (abbr. B6) mice. Gravity receptor function was measured using linear vestibular evoked potentials (VsEPs). Cage and swimming behaviors were also documented. Temporal bones were cleared to assess the overall otoconial deficit and to correlate structure and function for lm mice. Results confirmed the absence of VsEPs for mice that lacked otoconia completely. VsEP thresholds and amplitudes varied in mouse strains with variable loss of otoconia. Some heterozygotes also showed elevated VsEP thresholds in comparison to B6 mice. In lm mice, which have absent otoconia in the utricle and a variable loss of otoconia in the saccule, VsEPs were present and average P1/N1 amplitudes were highly correlated with the average loss of saccular otoconia (R = 0.77,p < 0.001). Cage and swimming behavior were not adversely affected in those animals with recordable VsEPs. Most, but not all, mice with absent VsEPs were unable to swim. Some animals were able to swim despite having no measurable gravity receptor response. The latter finding underscores the remarkable adaptive potential exhibited by neurobehavioral systems following profound sensory loss. It also shows that behavior alone may be an unreliable indicator of the extent of gravity receptor deficits.
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Affiliation(s)
- Sherri M Jones
- School of Medicine, University of Missouri, Columbia, MO 65212, USA.
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25
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Fuller PM, Jones TA, Jones SM, Fuller CA. Evidence for macular gravity receptor modulation of hypothalamic, limbic and autonomic nuclei. Neuroscience 2005; 129:461-71. [PMID: 15501603 DOI: 10.1016/j.neuroscience.2004.05.059] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/29/2004] [Indexed: 11/21/2022]
Abstract
Mice lacking normal vestibular gravity reception show altered homeostatic, circadian and autonomic responses to hypergravity (+G) exposure. Using c-Fos as a marker of neuronal activation, the current study identifies CNS nuclei that may be critical for initiating and integrating such responses to changes in vestibular signaling. This experiment utilized the mutant C57BL/6JEi-het mouse (het), which lacks macular otoconia and thus gravity receptor function. Following 2 h of 2G (2x Earth's gravity) exposure (via centrifugation) the neuronal responses of the het mice were compared with wildtype mice similarly exposed to 2G, as well as het and wildtype 1G controls. Wildtype mice exposed to 2G demonstrated robust c-Fos expression in multiple autonomic, hypothalamic and limbic nuclei, including: the lateral septum, bed nucleus of the stria terminalis, amygdala, paraventricular hypothalamus, dorsomedial hypothalamus, arcuate, suprachiasmatic hypothalamus, intergeniculate leaflet, dorsal raphe, parabrachial and locus coeruleus. The het mice exposed to 2G demonstrated little to null c-Fos expression in these nuclei with a few exceptions and, in general, a similar pattern of c-Fos to 1G controls. Data from this study further support the existence of a complex and extensive influence of the neurovestibular system on homeostatic, circadian and possibly autonomic regulatory systems.
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Affiliation(s)
- P M Fuller
- Section of Neurobiology, Physiology and Behavior, University of California, One Shields Avenue, Davis, CA 95616-8519, USA
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26
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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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Paffenholz R, Bergstrom RA, Pasutto F, Wabnitz P, Munroe RJ, Jagla W, Heinzmann U, Marquardt A, Bareiss A, Laufs J, Russ A, Stumm G, Schimenti JC, Bergstrom DE. Vestibular defects in head-tilt mice result from mutations in Nox3, encoding an NADPH oxidase. Genes Dev 2004; 18:486-91. [PMID: 15014044 PMCID: PMC374230 DOI: 10.1101/gad.1172504] [Citation(s) in RCA: 208] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
The vestibular system of the inner ear is responsible for the perception of motion and gravity. Key elements of this organ are otoconia, tiny biomineral particles in the utricle and the saccule. In response to gravity or linear acceleration, otoconia deflect the stereocilia of the hair cells, thus transducing kinetic movements into sensorineural action potentials. Here, we present an allelic series of mutations at the otoconia-deficient head tilt (het) locus, affecting the gene for NADPH oxidase 3 (Nox3). This series of mutations identifies for the first time a protein with a clear enzymatic function as indispensable for otoconia morphogenesis.
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Irons-Brown SR, Jones SM, Jones TA. The simultaneous in vivo perilymphatic perfusion of avian auditory and vestibular end organs. J Neurosci Methods 2003; 131:57-64. [PMID: 14659824 DOI: 10.1016/s0165-0270(03)00239-5] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Perilymphatic perfusion is a method that allows the control of fluid parameters throughout the perilymphatic space of the inner ear. We have evaluated a new method for continuous perilymphatic perfusion of the auditory and vestibular end organs with artificial perilymph (APL) in chickens. Perfusate temperature (39.0 degrees C), pH (7.4), osmolarity (328 +/- 2 mosm), and flow rate (2 microl/min) were carefully controlled. Independent functional tests of vestibular and auditory sensory systems were made throughout perfusion periods by recording peripheral compound action potentials (CAPs). The recordings provided a means of monitoring the status of hair cell transduction, synaptic transmission and collective primary afferent activation in response to auditory or vestibular gravity receptor stimuli. Auditory and vestibular responses were stable during perfusion. No significant changes occurred in vestibular or auditory CAP amplitudes during long-term perfusion (50-80 min, n=7) and responses remained stable in one animal perfused for over 3 h. To our knowledge, there have been no reports evaluating vestibular function under these conditions. This technique enables us to systematically study receptor pharmacology in the peripheral vestibular and auditory systems virtually simultaneously in vivo. The model is well suited for use in the study of the pharmacology and toxicology of inner ear sensory systems.
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Affiliation(s)
- Shunda R Irons-Brown
- Department of Physiology, University of Missouri-Columbia, Columbia, MO 65203, USA
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29
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Abstract
The molecular mechanisms for the transduction of light and chemical signals in animals are fairly well understood. In contrast, the processes by which the senses of touch, balance, hearing, and proprioception are transduced are still largely unknown. Biochemical approaches to identify transduction components are difficult to use with mechanosensory systems, but genetic approaches are proving more successful. Genetic research in several organisms has demonstrated the importance of cytoskeletal, extracellular, and membrane components for sensory mechanotransduction. In particular, researchers have identified channel proteins in the DEG/ENaC and TRP families that are necessary for signaling in a variety of mechanosensory cells. Proof that these proteins are components of the transduction channel, however, is incomplete.
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Affiliation(s)
- Glen G Ernstrom
- Department of Biological Sciences, 1012 Fairchild Center, Columbia University, 1212 Amsterdam Avenue, New York, NY 10027, USA.
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30
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Harrod CG, Baker JF. The vestibulo ocular reflex (VOR) in otoconia deficient head tilt (het) mutant mice versus wild type C57BL/6 mice. Brain Res 2003; 972:75-83. [PMID: 12711080 DOI: 10.1016/s0006-8993(03)02505-8] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The horizontal and vertical vestibulo ocular reflex (VOR) of head tilted (het) mutant mice was compared to C57BL/6 controls. Eye movements were recorded in darkness using a temporarily attached search coil. Contributions of semicircular canal versus otolith organ signals were investigated by providing a canal only (vertical axis) or canal plus otolith organ (horizontal axis) stimulus. In controls, rotations that stimulated only the canals (upright yaw and on tail roll) produced accurate VOR timing during middle frequency rotations at 0.5 Hz (gain 0.27, phase error 6 degrees), and a phase advanced VOR during low frequency rotations at 0.05 Hz (0.05, 115 degrees). In het mutant mice, these rotations produced a highly attenuated VOR response and phase errors at both 0.5 Hz (0.11, 42 degrees) and 0.05 Hz (0.01, 36 degrees). In controls, rotations that stimulated both the otolith organs and semicircular canals (upright roll and on tail yaw) produced higher VOR gains overall than were elicited during vertical axis rotations, with phase accurate VOR at both 0.5 Hz (0.52, 4 degrees) and 0.05 Hz (0.34, 9 degrees). In het mutant mice, these rotations produced a highly attenuated VOR response and phase errors at both 0.5 Hz (0.14, 51 degrees) and 0.05 Hz (0.01, 43 degrees). During constant velocity rotations about an earth horizontal axis, eye velocity bias and modulation were virtually absent in het mutant mice, while robust in controls. Control mice produced compensatory ocular deviations in response to static head tilt, but responses in het mice were weak and inconsistent. These results show that het mice not only lack all aspects of otolith mediated VOR, but also are deficient in canal mediated VOR. Because semicircular canals are normal in het mice, we conclude that central neurons of the canal VOR are dependent on otolith organ signals for normal performance.
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Affiliation(s)
- Christopher G Harrod
- Northwestern University, Department of Physiology and Institute for Neuroscience, 303 East Chicago Avenue, M211, Chicago, IL 60611, USA
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31
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Lockwood DR, Kwon B, Smith JC, Houpt TA. Behavioral effects of static high magnetic fields on unrestrained and restrained mice. Physiol Behav 2003; 78:635-40. [PMID: 12782218 DOI: 10.1016/s0031-9384(03)00040-4] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
High-strength static magnetic fields are common tools in clinical imaging, but the behavioral effects are not well characterized. Previous studies on rats showed that fields of 7 T or above produced locomotor circling, conditioned taste aversion (CTA) and c-Fos in vestibular nuclei. To determine the generality of the behavioral effects on a smaller species, we subjected restrained or unrestrained mice to 30-min exposures in a 14.1-T field. Mice were given saccharin immediately prior to magnet or sham exposure on 3 consecutive days. All mice exposed to the magnet developed a CTA, and a significant number displayed tight circling and suppression of rearing. Unrestrained mice exhibited larger effects than restrained mice. These effects, similar to the effects in rats, may be the result of a vestibular disturbance caused by the magnetic field.
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Affiliation(s)
- Denesa R Lockwood
- Department of Biological Science, Program in Neuroscience, Florida State University, BRF 209 MC 4340, Tallahassee, FL 32306-4340, USA
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32
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Chao HHJ, Mentzer SE, Schimenti JC, You Y. Overlapping deletions define novel embryonic lethal loci in the mouse t complex. Genesis 2003; 35:133-42. [PMID: 12533796 DOI: 10.1002/gene.10174] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
SUMMARY The t complex region of mouse chromosome 17 contains genetic information critical for embryonic development. To identify and map loci required for normal embryogenesis, a set of overlapping deletions (D17Aus9(df10J), D17Aus9(df12J), and D17Aus9(df13J)) surrounding the D17Aus9 locus and one encompassing the T locus, Del(17)T(7J), were bred in various combinations and the consequences of nullizygosity in overlapping regions were examined. The results indicated that there are at least two functional units within 1 cM of D17Aus9. l17J1 is a peri-implantation lethal mutation within the region deleted in D17Aus9(df13J), whereas l17J2 is a later-acting lethal defined by the region of overlap between Del(17)T(7J) and D17Aus9(df12J). Del(17)T(7J)/D17Aus9(df12J) embryos die around 10.5 dpc. The development of the mutant embryos is characterized by lack of axial rotation, an abnormal notochord structure, and a ballooning pericardium. These studies demonstrate the value of overlapping deletion complexes, as opposed to individual deletion complexes, for the identification, mapping, and analysis of genes required for embryonic development.
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Affiliation(s)
- Hanna H J Chao
- Life Sciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831-6445, USA
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33
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Mizuno R, Ijiri K. Otolith formation in a mutant Medaka with a deficiency in gravity-sensing. ADVANCES IN SPACE RESEARCH : THE OFFICIAL JOURNAL OF THE COMMITTEE ON SPACE RESEARCH (COSPAR) 2003; 32:1513-1520. [PMID: 15000116 DOI: 10.1016/s0273-1177(03)90389-9] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Mutant Medaka ha exhibit spontaneous mutation that is characterized by frequent inhibition or perturbation in the formation of utricular otoliths and/or semicircular canals. Three major features of otolith morphogenesis were observed in ha strain: 1) The initial appearance of otoliths was delayed, mispositioned, and malformed compared to normal embryos. 2) No utricular otoliths appeared on macula of any ha fry just after hatching. A symmetric state of otoliths was seen only when saccular otoliths were situated on macula in both inner ears. 3) In some fry, formation of utricular otoliths was observed in their later development. However, no new utricular otoliths appeared after fish were seventy or more days old after hatching. These observations show that otolith morphogenesis in ha is very different from that of wild-type. In this study, we classified adult ha into four different phenotypes using the existence or absence of utricular otoliths as our criteria. We concluded that dysfunction of utricular otoliths and semicircular canals cause a defect that affects the gravity-sensing abilities of medaka ha.
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Affiliation(s)
- R Mizuno
- Radioisotope Center, University of Tokyo, Yayoi, Bunkyo-ku, Tokyo, Japan.
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34
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Ijiri K. Life-Cycle Experiments of Medaka Fish Aboard the International Space Station. DEVELOPMENTAL BIOLOGY RESEARCH IN SPACE 2003; 9:201-16. [PMID: 14631634 DOI: 10.1016/s1569-2574(03)09008-7] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/10/2023]
Abstract
Fish are the most likely candidates to be the first vertebrate to live their life cycle aboard the International Space Station (ISS). In the space-shuttle experiment using medaka, the fry born in space had the same number of germ cells as the ground control fish, and these germ cells later developed to produce the offspring on the ground. Fry hatched in space did not exhibit any looping behavior regardless of their strain, visual acuity, etc. The aquatic habitat (AQH) is a space habitat designed for long-term breeding of medaka, zebrafish and Xenopus, and recent advancements in this hardware also support fish life-cycle experiments. From the crosses between two strains, fish having good eyesight and less sensitivity to gravity were obtained, and their tolerance to microgravity was tested by parabolic flight using an airplane. The fish exhibited less looping and no differences in degree of looping between light and dark conditions. These are possible candidates for the first adult medaka (parent fish) to start a life cycle aboard ISS. Embryos were treated with a three-dimensional clinostat. Such simulated microgravity caused no differences in tissue architecture or in gene expression within the retina, nor in formation of cartilage (head skeleton). Otolith formation in embryos and fry was investigated for wild-type and mutant (ha) medaka. The ha embryos could not form utricular otoliths. They formed saccular otoliths but with a delay. Fry of the mutant fish lacking the utricular otoliths are highly light-dependent at the time of hatching, showing a perfect dorsal-light response (DLR). As they grow, they eventually shift from being light dependent to gravity dependent. Continuous treatment of the fry with altered light direction suppressed this shift to gravity dependence. Being less dependent on gravity, these fish can serve as model fish in studying the differences expected for the fish that have experienced a life cycle in microgravity.
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Affiliation(s)
- Kenichi Ijiri
- Radioisotope Center, University of Tokyo, Yayoi, Bunkyo-ku, Tokyo 113-0032, Japan.
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35
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Ijiri K, Mizuno R, Eguchi H. Use of an otolith-deficient mutant in studies of fish behavior in microgravity. ADVANCES IN SPACE RESEARCH : THE OFFICIAL JOURNAL OF THE COMMITTEE ON SPACE RESEARCH (COSPAR) 2003; 32:1501-1512. [PMID: 15000112 DOI: 10.1016/s0273-1177(03)90388-7] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
The mutant strain (ha) of medaka (Oryzias latipes) lack utricular otoliths as fry, and some never form otoliths for life. The cross (F1 generation) between the strain having good eyesight and another strain having ordinary eyesight augmented visual acuity of the F1 generation. Crossing the good eyesight strain and ha mutant produced fish having good eyesight and less sensitivity to gravity in the F2 population. Their tolerance to microgravity was tested by parabolic flight using an airplane. The fish exhibited less looping and no differences in degree of looping between light and dark conditions, suggesting that loss of eyesight (in darkness) is not a direct cause for looping behavior in microgravity. The ha embryos could not form utricular otoliths. They did form saccular otoliths, but with a delay. Fry of the mutant fish lacking the utricular otoliths are highly dependent on light upon hatching and exhibit a perfect dorsal-light response (DLR). As they grow, they eventually shift from being light-dependent to being gravity-dependent. Continuous treatment of the fry with altered light direction suppressed this shift to gravity dependence. Being less dependent on gravity, these fish can serve as models in studying the differences expected for the vestibular system of fish reared in microgravity. When these fish were exposed to microgravity (parabolic flights) of an airplane, they spent far less time looping than fish reared in an ordinary light regimen.
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Affiliation(s)
- K Ijiri
- Radioisotope Center, University of Tokyo, Yayoi, Bunkyo-ku, Tokyo, Japan.
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36
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Fuller PM, Jones TA, Jones SM, Fuller CA. Neurovestibular modulation of circadian and homeostatic regulation: vestibulohypothalamic connection? Proc Natl Acad Sci U S A 2002; 99:15723-8. [PMID: 12434016 PMCID: PMC137783 DOI: 10.1073/pnas.242251499] [Citation(s) in RCA: 86] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2002] [Indexed: 11/18/2022] Open
Abstract
Chronic exposure to increased force environments (+G) has pronounced effects on the circadian and homeostatic regulation of body temperature (T(b)), ambulatory activity (Act), heart rate, feeding, and adiposity. By using the Brn 3.1 knockout mouse, which lacks vestibular hair cells, we recently described a major role of the vestibular system in mediating some of these adaptive responses. The present study used the C57BL6JEi-het mouse strain (het), which lacks macular otoconia, to elucidate the contribution of specific vestibular receptors. In this study, eight het and eight WT mice were exposed to 2G for 8 weeks by means of chronic centrifugation. In addition, eight het and eight WT mice were maintained as 1G controls in similar conditions. Upon 2G exposure, the WT exhibited a decrease in T(b) and an attenuated T(b) circadian rhythm. Act means and rhythms also were attenuated. Body mass and food intake were significantly lower than the 1G controls. After 8 weeks, percent body fat was significantly lower in the WT mice (P < 0.0001). In contrast, the het mice did not exhibit a decrease in mean T(b) and only a slight decrease in T(b) circadian amplitude. het Act levels were attenuated similarly to the WT mice. Body mass and food intake were only slightly attenuated in the het mice, and percent body fat, after 8 weeks, was not different in the 2G het group. These results link the vestibular macular receptors with specific alterations in homeostatic and circadian regulation.
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Affiliation(s)
- Patrick M Fuller
- Section of Neurobiology, Physiology and Behavior, University of California, Davis 95616, USA.
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37
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Kaartinen V, Nagy A, Gonzalez-Gomez I, Groffen J, Heisterkamp N. Vestibular dysgenesis in mice lacking Abr and Bcr Cdc42/RacGAPs. Dev Dyn 2002; 223:517-25. [PMID: 11921339 DOI: 10.1002/dvdy.10071] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
The inner ear develops from a simple epithelium (otic placode) into the complex structures specialized for balance (vestibule) and sound (cochlea) detection. Abnormal vestibular and cochlear development is associated with many birth defects. During recent years, considerable progress has been made in understanding the molecular bases of these conditions. To determine the biological function of two closely related GTPase activating proteins for the Cdc42/Rac GTPases, Abr and Bcr, we generated a mouse strain deficient in both of these proteins. Double null mutant mice exhibit hyperactivity, persistent circling, and are unable to swim. These phenotypes are typically found in mice with vestibular defects. Indeed, adult double null mutants display abnormal dysmorphic structures of both the saccule and utricle. Moreover, a total loss of otoconia can be seen in the utricle, whereas in the saccule, otoconia are either missing or their number is drastically decreased and they are abnormally large. Interestingly, both the cochlea and semicircular canals are normal and the double null mutant mice are not deaf. These data demonstrate that Abr and Bcr play important complementary roles during vestibular morphogenesis and that a function of Cdc42/RacGAPs and, therefore, that of the small Rho-related GTPases is critically important for balance and motor coordination.
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Affiliation(s)
- Vesa Kaartinen
- Developmental Biology Program, Department of Pathology and Laboratory Medicine, Childrens Hospital Los Angeles Research Institute, Los Angeles, California 90027, USA.
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38
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Goodwin NC, Ishida Y, Hartford S, Wnek C, Bergstrom RA, Leder P, Schimenti JC. DelBank: a mouse ES-cell resource for generating deletions. Nat Genet 2001; 28:310-1. [PMID: 11479588 DOI: 10.1038/91064] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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39
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Lyon MF, Schimenti JC, Evans EP. Narrowing the critical regions for mouse t complex transmission ratio distortion factors by use of deletions. Genetics 2000; 155:793-801. [PMID: 10835400 PMCID: PMC1461107 DOI: 10.1093/genetics/155.2.793] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Previously a deletion in mouse chromosome 17, T(22H), was shown to behave like a t allele of the t complex distorter gene Tcd1, and this was attributed to deletion of this locus. Seven further deletions are studied here, with the aim of narrowing the critical region in which Tcd1 must lie. One deletion, T(30H), together with three others, T(31H), T(33H), and T(36H), which extended more proximally, caused male sterility when heterozygous with a complete t haplotype and also enhanced transmission ratio of the partial t haplotype t(6), and this was attributed to deletion of the Tcd1 locus. The deletions T(29H), T(32H), and T(34H) that extended less proximally than T(30H) permitted male fertility when opposite a complete t haplotype. These results enabled narrowing of the critical interval for Tcd1 to between the markers D17Mit164 and D17Leh48. In addition, T(29H) and T(32H) enhanced the transmission ratio of t(6), but significantly less so than T(30H). T(34H) had no effect on transmission ratio. These results could be explained by a new distorter located between the breakpoints of T(29H) and T(34H) (between T and D17Leh66E). It is suggested that the original distorter Tcd1 in fact consists of two loci: Tcd1a, lying between D17Mit164 and D17Leh48, and Tcd1b, lying between T and D17Leh66E.
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Affiliation(s)
- M F Lyon
- MRC Mammalian Genetics Unit, Harwell, Didcot, Oxon, United Kingdom.
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40
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Planchart A, You Y, Schimenti JC. Physical mapping of male fertility and meiotic drive quantitative trait loci in the mouse t complex using chromosome deficiencies. Genetics 2000; 155:803-12. [PMID: 10835401 PMCID: PMC1461111 DOI: 10.1093/genetics/155.2.803] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
The t complex spans 20 cM of the proximal region of mouse chromosome 17. A variant form, the t haplotype (t), exists at significant frequencies in wild mouse populations and is characterized by the presence of inversions that suppress recombination with wild-type (+) chromosomes. Transmission ratio distortion and sterility are associated with t and affect males only. It is hypothesized that these phenomena are caused by trans-acting distorter/sterility factors that interact with a responder locus (Tcr(t)) and that the distorter and sterility factors are the same because homozygosity of the distorters causes male sterility. One factor, Tcd1, was previously shown to be amorphic using a chromosome deletion. To overcome limitations imposed by recombination suppression, we used a series of deletions within the t complex in trans to t chromosomes to characterize the Tcd1 region. We find that the distorter activity of Tcd1 is distinct from a linked sterility factor, originally called tcs1. YACs mapped with respect to deletion breakpoints localize tcs1 to a 1.1-Mb interval flanked by D17Aus9 and Tctex1. We present evidence for the existence of multiple proximal t complex regions that exhibit distorter activity. These studies demonstrate the utility of chromosome deletions for complex trait analysis.
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Affiliation(s)
- A Planchart
- The Jackson Laboratory, Bar Harbor, Maine 04609, USA
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41
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Abstract
Gravity receptor function was characterized in four mammalian species using far-field vestibular evoked potentials (VsEPs). VsEPs are compound action potentials of the vestibular nerve and central relays that are elicited by linear acceleration ramps applied to the cranium. Rats, mice, guinea pigs, and gerbils were studied. In all species, response onset occurred within 1.5 ms of the stimulus onset. Responses persisted during intense (116 dBSPL) wide-band (50 to 50,000 Hz) forward masking, whereas auditory responses to intense clicks (112 dBpeSPL) were eliminated under the same conditions. VsEPs remained after cochlear extirpation but were eliminated following bilateral labyrinthectomy. Responses included a series of positive and negative peaks that occurred within 8 ms of stimulus onset (range of means at +6 dBre: 1.0 g/ms: P1=908 to 1062 micros, N1=1342 to 1475 micros, P2=1632 to 1952 micros, N2=2038 to 2387 micros). Mean response amplitudes at +6 dBre: 1.0 g/ms ranged from 0.14 to 0.99 microV. VsEP input/output functions revealed latency slopes that varied across peaks and species ranging from -19 to -51 micros/dB. Amplitude-intensity slopes also varied ranging from 0.04 to 0.08 microV/dB for rats and mice. Latency values were comparable to those of birds although amplitudes were substantially smaller in mammals. VsEP threshold values were considerably higher in mammals compared to birds and ranged from -8.1 to -10.5 dBre 1.0 g/ms across species. These results support the hypothesis that mammalian gravity receptors are less sensitive to dynamic stimuli than are those of birds.
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Affiliation(s)
- T A Jones
- Departments of Surgery and Physiology, University of Missouri School of Medicine, 207 Allton Bldg., DC375.00, Columbia, MO, USA.
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42
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Jones SM, Erway LC, Bergstrom RA, Schimenti JC, Jones TA. Vestibular responses to linear acceleration are absent in otoconia-deficient C57BL/6JEi-het mice. Hear Res 1999; 135:56-60. [PMID: 10491954 DOI: 10.1016/s0378-5955(99)00090-8] [Citation(s) in RCA: 77] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
UNLABELLED Vestibular evoked potentials (VsEPs) were measured in normal mice and in mice homozygous for the head tilt mutation (het/het, abbr. het). The het mice lack otoconia, the inertial mass critical for natural stimulation of inner ear gravity receptors. Our findings demonstrate that vestibular neural responses to pulsed linear acceleration are absent in het mice. THE RESULTS (1) confirm that adequate sensory stimuli fail to activate gravity receptors in the het model; and (2) serve as definitive evidence that far-field vestibular responses to pulsed linear acceleration depend critically on otolith end organs. The C57BL/6JEi-het mouse may be an excellent model of gravity receptor sensory deprivation.
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Affiliation(s)
- S M Jones
- Department of Surgery/ENT, University of Missouri School of Medicine, Columbia 65212, USA
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