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Guan C, Shaikh M, Warnecke A, Vona B, Albert JT. A burden shared: The evolutionary case for studying human deafness in Drosophila. Hear Res 2024; 450:109047. [PMID: 38896942 DOI: 10.1016/j.heares.2024.109047] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/09/2024] [Revised: 05/09/2024] [Accepted: 05/24/2024] [Indexed: 06/21/2024]
Abstract
Hearing impairment is the most prevalent sensory disease in humans and can have dramatic effects on the development, and preservation, of our cognitive abilities and social interactions. Currently 20 % of the world's population suffer from a form of hearing impairment; this is predicted to rise to 25 % by 2050. Despite this staggering disease load, and the vast damage it inflicts on the social, medical and economic fabric of humankind, our ability to predict, or prevent, the loss of hearing is very poor indeed. We here make the case for a paradigm shift in our approach to studying deafness. By exploiting more forcefully the molecular-genetic conservation between human hearing and hearing in morphologically distinct models, such as the fruit fly Drosophila melanogaster, we believe, a deeper understanding of hearing and deafness can be achieved. An understanding that moves beyond the surface of the 'deafness genes' to probe the underlying bedrock of hearing, which is shared across taxa, and partly shared across modalities. When it comes to understanding the workings (and failings) of human sensory function, a simple fruit fly has a lot to offer and a fly eye might sometimes be a powerful model for a human ear. Particularly the use of fly avatars, in which specific molecular (genetic or proteomic) states of humans (e.g. specific patients) are experimentally reproduced, in order to study the corresponding molecular mechanisms (e.g. specific diseases) in a controlled yet naturalistic environment, is a tool that promises multiple unprecedented insights. The use of the fly - and fly avatars - would benefit humans and will help enhance the power of other scientific models, such as the mouse.
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Affiliation(s)
- Chonglin Guan
- Sensory Physiology & Behaviour Group, Department for Neuroscience, School of Medicine and Health Sciences, Carl von Ossietzky University Oldenburg, Carl von Ossietzky Str. 9-11, 26111 Oldenburg, Germany; Cluster of Excellence Hearing4all, Carl von Ossietzky University Oldenburg, Carl von Ossietzky Str. 9-11, 26111 Oldenburg, Germany
| | - Muhammad Shaikh
- Ear Institute, University College London, 332 Gray's Inn Road, London, WC1 × 8EE, UK
| | - Athanasia Warnecke
- Hannover Medical School, Department of Otorhinolaryngology, Head & Neck Surgery, Hannover, Germany; Cluster of Excellence Hearing4all, MHH Hannover, Germany
| | - Barbara Vona
- Institute of Human Genetics, University Medical Center Göttingen, 37073 Göttingen, Germany; Institute for Auditory Neuroscience and InnerEarLab, University Medical Center Göttingen, 37075 Göttingen, Germany.
| | - Joerg T Albert
- Sensory Physiology & Behaviour Group, Department for Neuroscience, School of Medicine and Health Sciences, Carl von Ossietzky University Oldenburg, Carl von Ossietzky Str. 9-11, 26111 Oldenburg, Germany; Cluster of Excellence Hearing4all, Carl von Ossietzky University Oldenburg, Carl von Ossietzky Str. 9-11, 26111 Oldenburg, Germany; Ear Institute, University College London, 332 Gray's Inn Road, London, WC1 × 8EE, UK.
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Ninoyu Y, Friedman RA. The genetic landscape of age-related hearing loss. Trends Genet 2024; 40:228-237. [PMID: 38161109 DOI: 10.1016/j.tig.2023.12.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2023] [Revised: 12/03/2023] [Accepted: 12/04/2023] [Indexed: 01/03/2024]
Abstract
Age-related hearing loss (ARHL) is a prevalent concern in the elderly population. Recent genome-wide and phenome-wide association studies (GWASs and PheWASs) have delved into the identification of causative variants and the understanding of pleiotropy, highlighting the polygenic intricacies of this complex condition. While recent large-scale GWASs have pinpointed significant SNPs and risk variants associated with ARHL, the detailed mechanisms, encompassing both genetic and epigenetic modifications, remain to be fully elucidated. This review presents the latest advances in association studies, integrating findings from both human studies and model organisms. By juxtaposing historical perspectives with contemporary genomics, we aim to catalyze innovative research and foster the development of novel therapeutic strategies for ARHL.
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Affiliation(s)
- Yuzuru Ninoyu
- Department of Otolaryngology-Head and Neck Surgery, University of California, San Diego, La Jolla, CA, USA; Department of Otolaryngology-Head and Neck Surgery, Kyoto Prefectural University of Medicine, Kyoto, Japan
| | - Rick A Friedman
- Department of Otolaryngology-Head and Neck Surgery, University of California, San Diego, La Jolla, CA, USA.
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Austin TT, Thomas CL, Warren B. Auditory robustness and resilience in the aging auditory system of the desert locust. Neurobiol Aging 2024; 133:39-50. [PMID: 37913625 DOI: 10.1016/j.neurobiolaging.2023.09.009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2023] [Revised: 09/19/2023] [Accepted: 09/19/2023] [Indexed: 11/03/2023]
Abstract
After overexposure to loud music, we experience a decrease in our ability to hear (robustness), which usually recovers (resilience). Here, we exploited the amenable auditory system of the desert locust, Schistocerca gregaria, to measure how robustness and resilience depend on age. We found that gene expression changes are dominated by age as opposed to noise exposure. We measured sound-evoked nerve activity for young and aged locusts directly, after 24 hours and 48 hours after noise exposure. We found that both young and aged locusts recovered their auditory nerve function over 48 hours. We also measured the sound-evoked transduction current in individual auditory neurons, and although the transduction current magnitude recovered in the young locusts after noise exposure, it failed to recover in the aged locusts. A plastic mechanism compensates for the decreased transduction current in aged locusts. We suggest key genes upregulated in young noise-exposed locusts that mediate robustness to noise exposure and find potential candidates responsible for compensatory mechanisms in the auditory neurons of aged noise-exposed locusts.
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Affiliation(s)
- Thomas T Austin
- Neurogenetics Group, College of Life Sciences, University of Leicester, Leicester LE1 7RH, UK
| | - Christian L Thomas
- Neurogenetics Group, College of Life Sciences, University of Leicester, Leicester LE1 7RH, UK
| | - Ben Warren
- Neurogenetics Group, College of Life Sciences, University of Leicester, Leicester LE1 7RH, UK.
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Warren B, Eberl D. What can insects teach us about hearing loss? J Physiol 2024; 602:297-316. [PMID: 38128023 DOI: 10.1113/jp281281] [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: 05/26/2023] [Accepted: 12/05/2023] [Indexed: 12/23/2023] Open
Abstract
Over the last three decades, insects have been utilized to provide a deep and fundamental understanding of many human diseases and disorders. Here, we present arguments for insects as models to understand general principles underlying hearing loss. Despite ∼600 million years since the last common ancestor of vertebrates and invertebrates, we share an overwhelming degree of genetic homology particularly with respect to auditory organ development and maintenance. Despite the anatomical differences between human and insect auditory organs, both share physiological principles of operation. We explain why these observations are expected and highlight areas in hearing loss research in which insects can provide insight. We start by briefly introducing the evolutionary journey of auditory organs, the reasons for using insect auditory organs for hearing loss research, and the tools and approaches available in insects. Then, the first half of the review focuses on auditory development and auditory disorders with a genetic cause. The second half analyses the physiological and genetic consequences of ageing and short- and long-term changes as a result of noise exposure. We finish with complex age and noise interactions in auditory systems. In this review, we present some of the evidence and arguments to support the use of insects to study mechanisms and potential treatments for hearing loss in humans. Obviously, insects cannot fully substitute for all aspects of human auditory function and loss of function, although there are many important questions that can be addressed in an animal model for which there are important ethical, practical and experimental advantages.
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Affiliation(s)
- Ben Warren
- Neurogenetics Group, College of Life Sciences, University of Leicester, Leicester, UK
| | - Daniel Eberl
- Department of Biology, University of Iowa, Iowa City, IA, USA
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Austin TT, Woodrow C, Pinchin J, Montealegre-Z F, Warren B. Effects of age and noise on tympanal displacement in the Desert Locust. JOURNAL OF INSECT PHYSIOLOGY 2024; 152:104595. [PMID: 38052320 DOI: 10.1016/j.jinsphys.2023.104595] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/19/2023] [Revised: 11/21/2023] [Accepted: 12/02/2023] [Indexed: 12/07/2023]
Abstract
Insect cuticle is an evolutionary-malleable exoskeleton that has specialised for various functions. Insects that detect the pressure component of sound bear specialised sound-capturing tympani evolved from cuticular thinning. Whilst the outer layer of insect cuticle is composed of non-living chitin, its mechanical properties change during development and aging. Here, we measured the displacements of the tympanum of the desert Locust, Schistocerca gregaria, to understand biomechanical changes as a function of age and noise-exposure. We found that the stiffness of the tympanum decreases within 12 h of noise-exposure and increases as a function of age, independent of noise-exposure. Noise-induced changes were dynamic with an increased tympanum displacement to sound within 12 h post noise-exposure. Within 24 h, however, the tone-evoked displacement of the tympanum decreased below that of control Locusts. After 48 h, the tone-evoked displacement of the tympanum was not significantly different to Locusts not exposed to noise. Tympanal displacements reduced predictably with age and repeatably noise-exposed Locusts (every three days) did not differ from their non-noise-exposed counterparts. Changes in the biomechanics of the tympanum may explain an age-dependent decrease in auditory detection in tympanal insects.
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Affiliation(s)
- Thomas T Austin
- College of Life Sciences, University of Leicester, Leicester LE1 7RH, UK
| | - Charlie Woodrow
- School of Life Sciences, University of Lincoln, Joseph Banks Laboratories, Lincoln LN6 7DL, UK
| | - James Pinchin
- Faculty of Engineering, University of Nottingham, University Park, Nottinghamshire NG7 2RD, UK
| | - Fernando Montealegre-Z
- School of Life Sciences, University of Lincoln, Joseph Banks Laboratories, Lincoln LN6 7DL, UK
| | - Ben Warren
- College of Life Sciences, University of Leicester, Leicester LE1 7RH, UK.
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Sharma Y, Jacobs JS, Sivan-Loukianova E, Lee E, Kernan MJ, Eberl DF. The retrograde IFT dynein is required for normal function of diverse mechanosensory cilia in Drosophila. Front Mol Neurosci 2023; 16:1263411. [PMID: 37808471 PMCID: PMC10556659 DOI: 10.3389/fnmol.2023.1263411] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2023] [Accepted: 09/07/2023] [Indexed: 10/10/2023] Open
Abstract
Introduction Cilia biogenesis relies on intraflagellar transport (IFT), a conserved transport mechanism which functions bi-directionally to bring protein complexes to the growing ciliary tip and recycle signaling and transport proteins between the cilium and cell body. In Drosophila, anterograde IFT is critical for assembly of sensory cilia in the neurons of both chordotonal (ch) organs, which have relatively long ciliary axonemes, and external sensory (es) organs, which have short axonemal segments with microtubules in distal sensory segments forming non-axonemal bundles. We previously isolated the beethoven (btv) mutant in a mutagenesis screen for auditory mutants. Although many btv mutant flies are deaf, some retain a small residual auditory function as determined both by behavior and by auditory electrophysiology. Results Here we molecularly characterize the btv gene and demonstrate that it encodes the IFT-associated dynein-2 heavy chain Dync2h1. We also describe morphological changes in Johnston's organ as flies age to 30 days, and we find that morphological and electrophysiological phenotypes in this ch organ of btv mutants become more severe with age. We show that NompB protein, encoding the conserved IFT88 protein, an IFT complex B component, fails to be cleared from chordotonal cilia in btv mutants, instead accumulating in the distorted cilia. In macrochaete bristles, a class of es organ, btv mutants show a 50% reduction in mechanoreceptor potentials. Discussion Thus, the btv-encoded Dync2h1 functions as the retrograde IFT motor in the assembly of long ciliary axonemes in ch organs and is also important for normal function of the short ciliary axonemes in es organs.
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Affiliation(s)
- Yashoda Sharma
- Department of Biology, The University of Iowa, Iowa City, IA, United States
| | - Julie S. Jacobs
- Department of Biology, The University of Iowa, Iowa City, IA, United States
| | | | - Eugene Lee
- Department of Neurobiology and Behavior, State University of New York, Stony Brook, NY, United States
| | - Maurice J. Kernan
- Department of Neurobiology and Behavior, State University of New York, Stony Brook, NY, United States
| | - Daniel F. Eberl
- Department of Biology, The University of Iowa, Iowa City, IA, United States
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Austin TT, Thomas CL, Lewis C, Blockley A, Warren B. Metabolic decline in an insect ear: correlative or causative for age-related auditory decline? Front Cell Dev Biol 2023; 11:1138392. [PMID: 37274746 PMCID: PMC10233746 DOI: 10.3389/fcell.2023.1138392] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2023] [Accepted: 04/25/2023] [Indexed: 06/06/2023] Open
Abstract
One leading hypothesis for why we lose our hearing as we age is a decrease in ear metabolism. However, direct measurements of metabolism across a lifespan in any auditory system are lacking. Even if metabolism does decrease with age, a question remains: is a metabolic decrease a cause of age-related auditory decline or simply correlative? We use an insect, the desert locust Schistocerca gregaria, as a physiologically versatile model to understand how cellular metabolism correlates with age and impacts on age-related auditory decline. We found that auditory organ metabolism decreases with age as measured fluorometrically. Next, we measured the individual auditory organ's metabolic rate and its sound-evoked nerve activity and found no correlation. We found no age-related change in auditory nerve activity, using hook electrode recordings, and in the electrophysiological properties of auditory neurons, using patch-clamp electrophysiology, but transduction channel activity decreased. To further test for a causative role of the metabolic rate in auditory decline, we manipulated metabolism of the auditory organ through diet and cold-rearing but found no difference in sound-evoked nerve activity. We found that although metabolism correlates with age-related auditory decline, it is not causative. Finally, we performed RNA-Seq on the auditory organs of young and old locusts, and whilst we found enrichment for Gene Ontology terms associated with metabolism, we also found enrichment for a number of additional aging GO terms. We hypothesize that age-related hearing loss is dominated by accumulative damage in multiple cell types and multiple processes which outweighs its metabolic decline.
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Zhang T, Li C, Deng J, Jia Y, Qu L, Ning Z. Chicken Hypothalamic and Ovarian DNA Methylome Alteration in Response to Forced Molting. Animals (Basel) 2023; 13:ani13061012. [PMID: 36978553 PMCID: PMC10044502 DOI: 10.3390/ani13061012] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2022] [Revised: 02/12/2023] [Accepted: 03/03/2023] [Indexed: 03/18/2023] Open
Abstract
Epigenetic modifications play an important role in regulating animal adaptation to external stress. To explore how DNA methylation regulates the expression levels of related genes during forced molting (FM) of laying hens, the hypothalamus and ovary tissues were analyzed at five periods using Whole-Genome Bisulfite Sequencing. The results show that methylation levels fluctuated differently in the exon, intron, 5′UTR, 3′UTR, promoter, and intergenic regions of the genome during FM. In addition, 16 differentially methylated genes (DMGs) regulating cell aging, immunity, and development were identified in the two reversible processes of starvation and redevelopment during FM. Comparing DMGs with differentially expressed genes (DEGs) obtained in the same periods, five hypermethylated DMGs (DSTYK, NKTR, SMOC1, SCAMP3, and ATOH8) that inhibited the expression of DEGs were found. Therefore, DMGs epigenetically modify the DEGs during the FM process of chickens, leading to the rapid closure and restart of their reproductive function and a re-increase in the egg-laying rate. Therefore, this study further confirmed that epigenetic modifications could regulate gene expression during FM and provides theoretical support for the subsequent optimization of FM technology.
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Affiliation(s)
- Tongyu Zhang
- Department of Animal Genetics and Breeding, College of Animal Science and Technology, China Agricultural University, Beijing 100193, China
| | - Chengfeng Li
- Hubei Shendan Healthy Food Co., Ltd., Xiaogan 432600, China
| | - Jianwen Deng
- Department of Animal Genetics and Breeding, College of Animal Science and Technology, China Agricultural University, Beijing 100193, China
| | - Yaxiong Jia
- Institute of Animal Science, Chinese Academy of Agricultural Sciences, Beijing 100091, China
| | - Lujiang Qu
- Department of Animal Genetics and Breeding, College of Animal Science and Technology, China Agricultural University, Beijing 100193, China
- National Engineering Laboratory for Animal Breeding, College of Animal Science and Technology, China Agricultural University, Beijing 100193, China
- State Key Laboratory of Animal Nutrition, Beijing 100193, China
| | - Zhonghua Ning
- Department of Animal Genetics and Breeding, College of Animal Science and Technology, China Agricultural University, Beijing 100193, China
- National Engineering Laboratory for Animal Breeding, College of Animal Science and Technology, China Agricultural University, Beijing 100193, China
- State Key Laboratory of Animal Nutrition, Beijing 100193, China
- Correspondence:
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Loh YM, Su MP, Ellis DA, Andrés M. The auditory efferent system in mosquitoes. Front Cell Dev Biol 2023; 11:1123738. [PMID: 36923250 PMCID: PMC10009176 DOI: 10.3389/fcell.2023.1123738] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2022] [Accepted: 02/17/2023] [Indexed: 03/02/2023] Open
Abstract
Whilst acoustic communication forms an integral component of the mating behavior of many insect species, it is particularly crucial for disease-transmitting mosquitoes; swarming males rely on hearing the faint sounds of flying females for courtship initiation. That males can hear females within the din of a swarm is testament to their fabulous auditory systems. Mosquito hearing is highly frequency-selective, remarkably sensitive and, most strikingly, supported by an elaborate system of auditory efferent neurons that modulate the auditory function - the only documented example amongst insects. Peripheral release of octopamine, serotonin and GABA appears to differentially modulate hearing across major disease-carrying mosquito species, with receptors from other neurotransmitter families also identified in their ears. Because mosquito mating relies on hearing the flight tones of mating partners, the auditory efferent system offers new potential targets for mosquito control. It also represents a unique insect model for studying auditory efferent networks. Here we review current knowledge of the mosquito auditory efferent system, briefly compare it with its counterparts in other species and highlight future research directions to unravel its contribution to mosquito auditory perception.
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Affiliation(s)
- YuMin M. Loh
- Graduate School of Science, Nagoya University, Nagoya, Aichi, Japan
| | - Matthew P. Su
- Graduate School of Science, Nagoya University, Nagoya, Aichi, Japan
- Institute for Advanced Research, Nagoya University, Nagoya, Aichi, Japan
| | - David A. Ellis
- UCL Ear Institute, University College London, London, United Kingdom
- The Francis Crick Institute, London, United Kingdom
| | - Marta Andrés
- UCL Ear Institute, University College London, London, United Kingdom
- The Francis Crick Institute, London, United Kingdom
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10
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Kang DS, Kim Y, Stanley D. What is in a model? ARCHIVES OF INSECT BIOCHEMISTRY AND PHYSIOLOGY 2023; 112:e21972. [PMID: 36164283 DOI: 10.1002/arch.21972] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/03/2022] [Revised: 08/25/2022] [Accepted: 08/26/2022] [Indexed: 06/16/2023]
Abstract
After reading contradictory claims of model status for some insect species, we feel a brief discussion of the topic may be useful. Here, we document a few examples where clarity on model status seems to be lacking, briefly review work on widely recognized models, and offer criteria for including any given species as a model organism.
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Affiliation(s)
- David S Kang
- USDA/Agricultural Research Service, Biological Control of Insects Research Laboratory, Columbia, Missouri, USA
| | - Yonggyun Kim
- Department of Plant Medicals, College of Life Sciences, Andong National University, Andong, South Korea
| | - David Stanley
- USDA/Agricultural Research Service, Biological Control of Insects Research Laboratory, Columbia, Missouri, USA
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11
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Requena T, Keder A, zur Lage P, Albert JT, Jarman AP. A Drosophila model for Meniere's disease: Dystrobrevin is required for support cell function in hearing and proprioception. Front Cell Dev Biol 2022; 10:1015651. [PMID: 36438562 PMCID: PMC9688402 DOI: 10.3389/fcell.2022.1015651] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2022] [Accepted: 10/27/2022] [Indexed: 08/04/2023] Open
Abstract
Meniere's disease (MD) is an inner ear disorder characterised by recurrent vertigo attacks associated with sensorineural hearing loss and tinnitus. Evidence from epidemiology and Whole Exome Sequencing (WES) suggests a genetic susceptibility involving multiple genes, including α-Dystrobrevin (DTNA). Here we investigate a Drosophila model. We show that mutation, or knockdown, of the DTNA orthologue in Drosophila, Dystrobrevin (Dyb), results in defective proprioception and impaired function of Johnston's Organ (JO), the fly's equivalent of the inner ear. Dyb and another component of the dystrophin-glycoprotein complex (DGC), Dystrophin (Dys), are expressed in support cells within JO. Their specific locations suggest that they form part of support cell contacts, thereby helping to maintain the integrity of the hemolymph-neuron diffusion barrier, which is equivalent to a blood-brain barrier. These results have important implications for the human condition, and notably, we note that DTNA is expressed in equivalent cells of the mammalian inner ear.
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Affiliation(s)
- T. Requena
- Biomedical Sciences: Centre for Discovery Brain Sciences, Edinburgh Medical School, University of Edinburgh, Edinburgh, United Kingdom
- Division of Functional Genetics and Development, The Royal Dick School of Veterinary Sciences, The Roslin Institute, The University of Edinburgh, Edinburgh, United Kingdom
| | - A. Keder
- Ear Institute, University College London, London, United Kingdom
| | - P. zur Lage
- Biomedical Sciences: Centre for Discovery Brain Sciences, Edinburgh Medical School, University of Edinburgh, Edinburgh, United Kingdom
| | - J. T. Albert
- Ear Institute, University College London, London, United Kingdom
| | - A. P. Jarman
- Biomedical Sciences: Centre for Discovery Brain Sciences, Edinburgh Medical School, University of Edinburgh, Edinburgh, United Kingdom
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12
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Blockley A, Ogle D, Woodrow C, Montealegre-Z F, Warren B. Physiological changes throughout an insect ear due to age and noise - a longitudinal study. iScience 2022; 25:104746. [PMID: 36034233 PMCID: PMC9400085 DOI: 10.1016/j.isci.2022.104746] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2022] [Revised: 06/06/2022] [Accepted: 06/07/2022] [Indexed: 11/20/2022] Open
Abstract
Hearing loss is not unique to humans and is experienced by all animals in the face of wild and eclectic differences in ear morphology. Here, we exploited the high throughput and accessible tympanal ear of the desert locust, Schistocerca gregaria to rigorously quantify changes in the auditory system due to noise exposure and age. In this exploratory study, we analyzed tympanal displacements, morphology of the auditory Müller’s organ and measured activity of the auditory nerve, the transduction current, and electrophysiological properties of individual auditory receptors. This work shows that hearing loss manifests as a complex disorder due to differential effects of age and noise on several processes and cell types within the ear. The “middle-aged deafness” pattern of hearing loss found in locusts mirrors that found for humans exposed to noise early in their life suggesting a fundamental interaction of the use of an auditory system (noise) and its aging. Locusts routinely exposed to noise follow same pattern of hearing loss as humans Parts of the auditory system are affected by noise, age, or both noise and age Hearing loss is a multifaceted disorder caused by defects in distinct ear processes
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13
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Strauß J, Stritih-Peljhan N. Vibration detection in arthropods: Signal transfer, biomechanics and sensory adaptations. ARTHROPOD STRUCTURE & DEVELOPMENT 2022; 68:101167. [PMID: 35576788 DOI: 10.1016/j.asd.2022.101167] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/05/2021] [Revised: 04/07/2022] [Accepted: 04/14/2022] [Indexed: 06/15/2023]
Abstract
In arthropods, the detection of vibrational signals and stimuli is essential in several behaviours, including mate recognition and pair formation, prey detection, and predator evasion. These behaviours have been studied in several species of insects, arachnids, and crustaceans for vibration production and propagation in the environment. Vibration stimuli are transferred over the animals' appendages and the body to vibrosensory organs. Ultimately, the stimuli are transferred to act on the dendrites of the mechanosensitive sensilla. We refer to these two different levels of transfer as macromechanics and micromechanics, respectively. These biomechanical processes have important roles in filtering and pre-processing of stimuli, which are not carried out by neuronal components of sensory organs. Also, the macromechanical transfer is posture-dependent and enables behavioural control of vibration detection. Diverse sensory organs respond to vibrations, including cuticular sensilla (slit sensilla, campaniform sensilla) and internal chordotonal organs. These organs provide various adaptations, as they occur at diverse body positions with different mechanical couplings as input pathways. Macromechanics likely facilitated evolution of vibrosensory organs at specific body locations. Thus, vibration detection is a highly complex sensory capacity, which employs body and sensory mechanics for signal filtering, amplification, and analysis of frequency, intensity and directionality.
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Affiliation(s)
- Johannes Strauß
- AG Integrative Sensory Physiology, Institute for Animal Physiology, Justus Liebig University Gießen, Gießen, Germany; Center for Mind, Brain and Behavior (CMBB), University of Marburg and Justus Liebig University Gießen, Germany.
| | - Nataša Stritih-Peljhan
- National Institute of Biology, Department of Organisms and Ecosystems Research, Ljubljana, Slovenia.
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14
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Paplou V, Schubert NMA, Pyott SJ. Age-Related Changes in the Cochlea and Vestibule: Shared Patterns and Processes. Front Neurosci 2021; 15:680856. [PMID: 34539328 PMCID: PMC8446668 DOI: 10.3389/fnins.2021.680856] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2021] [Accepted: 07/20/2021] [Indexed: 12/16/2022] Open
Abstract
Both age-related hearing loss (ARHL) and age-related loss in vestibular function (ARVL) are prevalent conditions with deleterious consequences on the health and quality of life. Age-related changes in the inner ear are key contributors to both conditions. The auditory and vestibular systems rely on a shared sensory organ - the inner ear - and, like other sensory organs, the inner ear is susceptible to the effects of aging. Despite involvement of the same sensory structure, ARHL and ARVL are often considered separately. Insight essential for the development of improved diagnostics and treatments for both ARHL and ARVL can be gained by careful examination of their shared and unique pathophysiology in the auditory and vestibular end organs of the inner ear. To this end, this review begins by comparing the prevalence patterns of ARHL and ARVL. Next, the normal and age-related changes in the structure and function of the auditory and vestibular end organs are compared. Then, the contributions of various molecular mechanisms, notably inflammaging, oxidative stress, and genetic factors, are evaluated as possible common culprits that interrelate pathophysiology in the cochlea and vestibular end organs as part of ARHL and ARVL. A careful comparison of these changes reveals that the patterns of pathophysiology show similarities but also differences both between the cochlea and vestibular end organs and among the vestibular end organs. Future progress will depend on the development and application of new research strategies and the integrated investigation of ARHL and ARVL using both clinical and animal models.
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Affiliation(s)
- Vasiliki Paplou
- Department of Otorhinolaryngology and Head/Neck Surgery, University of Groningen, University Medical Center Groningen, Groningen, Netherlands
| | - Nick M A Schubert
- Department of Otorhinolaryngology and Head/Neck Surgery, University of Groningen, University Medical Center Groningen, Groningen, Netherlands.,Research School of Behavioural and Cognitive Neurosciences, Graduate School of Medical Sciences, University of Groningen, Groningen, Netherlands
| | - Sonja J Pyott
- Department of Otorhinolaryngology and Head/Neck Surgery, University of Groningen, University Medical Center Groningen, Groningen, Netherlands.,Research School of Behavioural and Cognitive Neurosciences, Graduate School of Medical Sciences, University of Groningen, Groningen, Netherlands
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15
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Warren B, Nowotny M. Bridging the Gap Between Mammal and Insect Ears – A Comparative and Evolutionary View of Sound-Reception. Front Ecol Evol 2021. [DOI: 10.3389/fevo.2021.667218] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Insects must wonder why mammals have ears only in their head and why they evolved only one common principle of ear design—the cochlea. Ears independently evolved at least 19 times in different insect groups and therefore can be found in completely different body parts. The morphologies and functional characteristics of insect ears are as wildly diverse as the ecological niches they exploit. In both, insects and mammals, hearing organs are constrained by the same biophysical principles and their respective molecular processes for mechanotransduction are thought to share a common evolutionary origin. Due to this, comparative knowledge of hearing across animal phyla provides crucial insight into fundamental processes of auditory transduction, especially at the biomechanical and molecular level. This review will start by comparing hearing between insects and mammals in an evolutionary context. It will then discuss current findings about sound reception will help to bridge the gap between both research fields.
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16
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French AS, Warren B. Gene transcription changes in a locust model of noise-induced deafness. J Neurophysiol 2021; 125:2264-2278. [PMID: 33949886 PMCID: PMC8285658 DOI: 10.1152/jn.00119.2021] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Locusts have auditory structures called Müller’s organs attached to tympanic membranes on either side of the abdomen. We measured the normalized abundances of 500 different mRNA transcripts in 320 Müller’s organs obtained from 160 locusts (Schistocerca gregaria) that had been subjected to a loud continuous 3-kHz tone for 24 h. Abundance ratios were then measured relative to transcripts from 360 control organs. A histogram of the number of observed transcripts versus their abundance ratios (noise exposed/control) was well fitted by a Cauchy distribution with median value near one. Transcripts below 5% and above 95% of the cumulative distribution function of the fitted Cauchy distribution were selected as putatively different from the expected values of an untreated preparation. This yielded eight transcripts with ratios increased by noise exposure (ratios 1.689–3.038) and 18 transcripts with reduced ratios (0.069–0.457). Most of the transcripts with increased abundance represented genes responsible for cuticular construction, suggesting extensive remodeling of some or all the cuticular components of the auditory structure, whereas the reduced abundance transcripts were mostly involved in lipid and protein storage and metabolism, suggesting a profound reduction in metabolic activity in response to the overstimulation. NEW & NOTEWORTHY Locust ears have functional and genetic similarities to human ears, including loss of hearing from age or noise exposure. We measured transcript abundances in transcriptomes of noise-exposed and control locust ears. The data indicate remodeling of the ear tympanum and profound reductions in metabolism that may explain reduced sound transduction. These findings advance our understanding of this useful model and suggest further experiments to elucidate mechanisms that ears use to cope with excessive stimulation.
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Affiliation(s)
- Andrew S French
- Department of Physiology and Biophysics, Dalhousie University, Halifax, Nova Scotia, Canada
| | - Ben Warren
- Department of Neuroscience, Psychology and Behavior, University of Leicester, Leicester, United Kingdom
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17
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Boyd-Gibbins N, Tardieu CH, Blunskyte M, Kirkwood N, Somers J, Albert JT. Turnover and activity-dependent transcriptional control of NompC in the Drosophila ear. iScience 2021; 24:102486. [PMID: 34027326 PMCID: PMC8134069 DOI: 10.1016/j.isci.2021.102486] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2020] [Revised: 02/17/2021] [Accepted: 04/27/2021] [Indexed: 01/17/2023] Open
Abstract
Across their lives, biological sensors maintain near-constant functional outputs despite countless exogenous and endogenous perturbations. This sensory homeostasis is the product of multiple dynamic equilibria, the breakdown of which contributes to age-related decline. The mechanisms of homeostatic maintenance, however, are still poorly understood. The ears of vertebrates and insects are characterized by exquisite sensitivities but also by marked functional vulnerabilities. Being under the permanent load of thermal and acoustic noise, auditory transducer channels exemplify the homeostatic challenge. We show that (1) NompC-dependent mechanotransducers in the ear of the fruit fly Drosophila melanogaster undergo continual replacement with estimated turnover times of 9.1 hr; (2) a de novo synthesis of NompC can restore transducer function in the adult ears of congenitally hearing-impaired flies; (3) key components of the auditory transduction chain, including NompC, are under activity-dependent transcriptional control, likely forming a transducer-operated mechanosensory gain control system that extends beyond hearing organs. De novo NompC synthesis restores auditory transduction in congenitally deafened flies. Complete turnover of NompC mechanotransducers within less than 24 hr. Activity-dependent transcriptional control of transducers controls auditory function.
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Affiliation(s)
| | - Camille H Tardieu
- Ear Institute, University College London, 332 Gray's Inn Road, London WC1X 8EE, UK
| | - Modesta Blunskyte
- Ear Institute, University College London, 332 Gray's Inn Road, London WC1X 8EE, UK
| | - Nerissa Kirkwood
- Ear Institute, University College London, 332 Gray's Inn Road, London WC1X 8EE, UK
| | - Jason Somers
- Ear Institute, University College London, 332 Gray's Inn Road, London WC1X 8EE, UK.,The Francis Crick Institute, 1 Midland Road, London NW1 1AT, UK
| | - Joerg T Albert
- Ear Institute, University College London, 332 Gray's Inn Road, London WC1X 8EE, UK.,The Francis Crick Institute, 1 Midland Road, London NW1 1AT, UK.,Centre for Mathematics and Physics in the Life Sciences and Experimental Biology (CoMPLEX), University College London, Gower Street, London WC1E 6BT, UK.,Department of Cell and Developmental Biology, University College London, Gower Street, London WC1E 6DE, UK
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