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Coffin AB, Dale E, Molano O, Pederson A, Costa EK, Chen J. Age-related changes in the zebrafish and killifish inner ear and lateral line. Sci Rep 2024; 14:6670. [PMID: 38509148 PMCID: PMC10954678 DOI: 10.1038/s41598-024-57182-z] [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: 10/06/2023] [Accepted: 03/14/2024] [Indexed: 03/22/2024] Open
Abstract
Age-related hearing loss (ARHL) is a debilitating disorder for millions worldwide. While there are multiple underlying causes of ARHL, one common factor is loss of sensory hair cells. In mammals, new hair cells are not produced postnatally and do not regenerate after damage, leading to permanent hearing impairment. By contrast, fish produce hair cells throughout life and robustly regenerate these cells after toxic insult. Despite these regenerative abilities, zebrafish show features of ARHL. Here, we show that aged zebrafish of both sexes exhibited significant hair cell loss and decreased cell proliferation in all inner ear epithelia (saccule, lagena, utricle). Ears from aged zebrafish had increased expression of pro-inflammatory genes and significantly more macrophages than ears from young adult animals. Aged zebrafish also had fewer lateral line hair cells and less cell proliferation than young animals, although lateral line hair cells still robustly regenerated following damage. Unlike zebrafish, African turquoise killifish (an emerging aging model) only showed hair cell loss in the saccule of aged males, but both sexes exhibit age-related changes in the lateral line. Our work demonstrates that zebrafish exhibit key features of auditory aging, including hair cell loss and increased inflammation. Further, our finding that aged zebrafish have fewer lateral line hair cells yet retain regenerative capacity, suggests a decoupling of homeostatic hair cell addition from regeneration following acute trauma. Finally, zebrafish and killifish show species-specific strategies for lateral line homeostasis that may inform further comparative research on aging in mechanosensory systems.
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Affiliation(s)
- Allison B Coffin
- College of Arts and Sciences, Washington State University Vancouver, Vancouver, WA, 98686, USA.
- Department of Integrative Physiology and Neuroscience, Washington State University Vancouver, Vancouver, WA, 98686, USA.
| | - Emily Dale
- College of Arts and Sciences, Washington State University Vancouver, Vancouver, WA, 98686, USA
- Neuroimmunology Research, Mayo Clinic, Rochester, MN, 55902, USA
| | - Olivia Molano
- College of Arts and Sciences, Washington State University Vancouver, Vancouver, WA, 98686, USA
- Neuroscience Graduate Program, Brown University, Providence, RI, 02912, USA
| | - Alexandra Pederson
- College of Arts and Sciences, Washington State University Vancouver, Vancouver, WA, 98686, USA
- Department of Behavioral Neuroscience, Oregon Health & Science University, Portland, OR, 97239, USA
| | - Emma K Costa
- Department of Neurology and Neurological Sciences, Stanford University, Stanford, CA, 94305, USA
- Neurosciences Interdepartmental Program, Stanford University School of Medicine, Stanford, CA, 94305, USA
| | - Jingxun Chen
- Department of Genetics, Stanford University, Stanford, CA, 94305, USA
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Kalka M, Bielak K, Ptak M, Stolarski J, Dobryszycki P, Wojtas M. Calcium carbonate polymorph selection in fish otoliths: A key role of phosphorylation of Starmaker-like protein. Acta Biomater 2024; 174:437-446. [PMID: 38061675 DOI: 10.1016/j.actbio.2023.11.039] [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: 09/05/2023] [Revised: 11/27/2023] [Accepted: 11/30/2023] [Indexed: 12/21/2023]
Abstract
Fish otoliths are calcium carbonate biominerals found in the inner ear commonly used for tracking fish biochronologies and as a model system for biomineralization. The process of fish otolith formation is biologically controlled by numerous biomacromolecules which not only affect crystal size, shape, mechanical properties, but also selection of calcium carbonate polymorph (e.g., aragonite, vaterite). The proteinaceous control over calcium carbonate polymorph selection occurs in many other species (e.g., corals, mollusks, echinoderms) but the exact mechanism of protein interactions with calcium and carbonate ions - constituents of CaCO3 - are not fully elucidated. Herein, we focus on a native Starmaker-like protein isolated from vaterite asteriscus otoliths from Cyprinus carpio. The proteomic studies show the presence of the phosphorylated protein in vaterite otoliths. In a series of in vitro mineralization experiments with Starmaker-like, we show that native phosphorylation is a crucial determinant for the selection of a crystal's polymorphic form. This is the first report showing that the switch in calcium carbonate phase depends on the phosphorylation pattern of a single isolated protein. STATEMENT OF SIGNIFICANCE: Calcium carbonate has numerous applications in industry and medicine. However, we still do not understand the mechanism of biologically driven polymorph selection which results in specific biomineral properties. Previous work on calcium carbonate biominerals showed that either several macromolecular factors or high magnesium concentration (non-physiological) are required for proper polymorph selection (e.g., in mollusk shells, corals and otoliths). In this work, we showed for the first time that protein phosphorylation is a crucial factor for controlling the calcium carbonate crystal phase. This is important because a single protein from the otolith organic matrix could switch between polymorphs depending on the phosphorylation level. It seems that protein post-translational modifications (native, not artificial) are more important for biomolecular control of crystal growth than previously considered.
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Affiliation(s)
- Marta Kalka
- Wroclaw University of Science and Technology, Faculty of Chemistry, Department of Biochemistry, Molecular Biology and Biotechnology, Wrocław, Poland
| | - Klaudia Bielak
- Wroclaw University of Science and Technology, Faculty of Chemistry, Department of Biochemistry, Molecular Biology and Biotechnology, Wrocław, Poland
| | - Maciej Ptak
- Division of Optical Spectroscopy, Institute of Low Temperature and Structure Research, Polish Academy of Sciences, Wrocław, Poland
| | | | - Piotr Dobryszycki
- Wroclaw University of Science and Technology, Faculty of Chemistry, Department of Biochemistry, Molecular Biology and Biotechnology, Wrocław, Poland
| | - Magdalena Wojtas
- Wroclaw University of Science and Technology, Faculty of Chemistry, Department of Biochemistry, Molecular Biology and Biotechnology, Wrocław, Poland.
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Araújo R, David R, Benoit J, Lungmus JK, Stoessel A, Barrett PM, Maisano JA, Ekdale E, Orliac M, Luo ZX, Martinelli AG, Hoffman EA, Sidor CA, Martins RMS, Spoor F, Angielczyk KD. Inner ear biomechanics reveals a Late Triassic origin for mammalian endothermy. Nature 2022; 607:726-731. [PMID: 35859179 DOI: 10.1038/s41586-022-04963-z] [Citation(s) in RCA: 18] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2021] [Accepted: 06/10/2022] [Indexed: 01/12/2023]
Abstract
Endothermy underpins the ecological dominance of mammals and birds in diverse environmental settings1,2. However, it is unclear when this crucial feature emerged during mammalian evolutionary history, as most of the fossil evidence is ambiguous3-17. Here we show that this key evolutionary transition can be investigated using the morphology of the endolymph-filled semicircular ducts of the inner ear, which monitor head rotations and are essential for motor coordination, navigation and spatial awareness18-22. Increased body temperatures during the ectotherm-endotherm transition of mammal ancestors would decrease endolymph viscosity, negatively affecting semicircular duct biomechanics23,24, while simultaneously increasing behavioural activity25,26 probably required improved performance27. Morphological changes to the membranous ducts and enclosing bony canals would have been necessary to maintain optimal functionality during this transition. To track these morphofunctional changes in 56 extinct synapsid species, we developed the thermo-motility index, a proxy based on bony canal morphology. The results suggest that endothermy evolved abruptly during the Late Triassic period in Mammaliamorpha, correlated with a sharp increase in body temperature (5-9 °C) and an expansion of aerobic and anaerobic capacities. Contrary to previous suggestions3-14, all stem mammaliamorphs were most probably ectotherms. Endothermy, as a crucial physiological characteristic, joins other distinctive mammalian features that arose during this period of climatic instability28.
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Affiliation(s)
- Ricardo Araújo
- Instituto de Plasmas e Fusão Nuclear, Instituto Superior Técnico, Universidade de Lisboa, Lisboa, Portugal. .,Institut des Sciences de L'Évolution de Montpellier, Université de Montpellier, Montpellier, France.
| | - Romain David
- Natural History Museum, London, UK. .,Max Plank Institute for Evolutionary Anthropology, Leipzig, Germany.
| | - Julien Benoit
- Evolutionary Studies Institute, University of Witwatersrand, Johannesburg, South Africa
| | - Jacqueline K Lungmus
- Department of Paleobiology, National Museum of Natural History, Washington DC, USA
| | - Alexander Stoessel
- Max Plank Institute for Evolutionary Anthropology, Leipzig, Germany.,Institute of Zoology and Evolutionary Research, Friedrich Schiller University Jena, Jena, Germany
| | | | - Jessica A Maisano
- Jackson School of Geosciences, University of Texas at Austin, Austin, TX, USA
| | - Eric Ekdale
- Department of Biology, San Diego State University, San Diego, CA, USA.,Department of Paleontology, San Diego Natural History Museum, San Diego, CA, USA
| | - Maëva Orliac
- Institut des Sciences de L'Évolution de Montpellier, Université de Montpellier, Montpellier, France
| | - Zhe-Xi Luo
- Department of Organismal Biology and Anatomy, University of Chicago, Chicago, IL, USA
| | - Agustín G Martinelli
- Museo Argentino de Ciencias Naturales 'Bernardino Rivadavia', Buenos Aires, Argentina
| | - Eva A Hoffman
- Division of Paleontology, American Museum of Natural History, New York, NY, USA
| | - Christian A Sidor
- Burke Museum and Department of Biology, University of Washington, Seattle, WA, USA
| | - Rui M S Martins
- Instituto de Plasmas e Fusão Nuclear, Instituto Superior Técnico, Universidade de Lisboa, Lisboa, Portugal
| | - Fred Spoor
- Natural History Museum, London, UK.,Max Plank Institute for Evolutionary Anthropology, Leipzig, Germany.,Department of Anthropology, University College London, London, UK
| | - Kenneth D Angielczyk
- Neguanee Integrative Research Center, Field Museum of Natural History, Chicago, IL, USA.
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4
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Rabbitt RD. Semicircular canal biomechanics in health and disease. J Neurophysiol 2019; 121:732-755. [PMID: 30565972 PMCID: PMC6520623 DOI: 10.1152/jn.00708.2018] [Citation(s) in RCA: 46] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2018] [Revised: 12/11/2018] [Accepted: 12/11/2018] [Indexed: 12/12/2022] Open
Abstract
The semicircular canals are responsible for sensing angular head motion in three-dimensional space and for providing neural inputs to the central nervous system (CNS) essential for agile mobility, stable vision, and autonomic control of the cardiovascular and other gravity-sensitive systems. Sensation relies on fluid mechanics within the labyrinth to selectively convert angular head acceleration into sensory hair bundle displacements in each of three inner ear sensory organs. Canal afferent neurons encode the direction and time course of head movements over a broad range of movement frequencies and amplitudes. Disorders altering canal mechanics result in pathological inputs to the CNS, often leading to debilitating symptoms. Vestibular disorders and conditions with mechanical substrates include benign paroxysmal positional nystagmus, direction-changing positional nystagmus, alcohol positional nystagmus, caloric nystagmus, Tullio phenomena, and others. Here, the mechanics of angular motion transduction and how it contributes to neural encoding by the semicircular canals is reviewed in both health and disease.
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Affiliation(s)
- R. D. Rabbitt
- Department of Biomedical Engineering, University of Utah, Salt Lake City, Utah
- Otolaryngology-Head Neck Surgery, University of Utah, Salt Lake City, Utah
- Neuroscience Program, University of Utah, Salt Lake City, Utah
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5
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Hawkins AD, Popper AN. Directional hearing and sound source localization by fishes. THE JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA 2018; 144:3329. [PMID: 30599653 DOI: 10.1121/1.5082306] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/04/2018] [Accepted: 11/20/2018] [Indexed: 06/09/2023]
Abstract
Directional hearing may enable fishes to seek out prey, avoid predators, find mates, and detect important spatial cues. Early sound localization experiments gave negative results, and it was thought unlikely that fishes utilized the same direction-finding mechanisms as terrestrial vertebrates. However, fishes swim towards underwater sound sources, and some can discriminate between sounds from different directions and distances. The otolith organs of the inner ear detect the particle motion components of sound, acting as vector detectors through the presence of sensory hair cells with differing orientation. However, many questions remain on inner ear functioning. There are problems in understanding the actual mechanisms involved in determining sound direction and distance. Moreover, very little is still known about the ability of fishes to locate sound sources in three-dimensional space. Do fishes swim directly towards a source, or instead "sample" sound levels while moving towards the source? To what extent do fishes utilize other senses and especially vision in locating the source? Further behavioral studies of free-swimming fishes are required to provide better understanding of how fishes might actually locate sound sources. In addition, more experiments are required on the auditory mechanism that fishes may utilize.
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Affiliation(s)
| | - Arthur N Popper
- Department of Biology, University of Maryland, College Park, Maryland 20742, USA
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6
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Schulz-Mirbach T, Ladich F, Plath M, Heß M. Enigmatic ear stones: what we know about the functional role and evolution of fish otoliths. Biol Rev Camb Philos Soc 2018; 94:457-482. [DOI: 10.1111/brv.12463] [Citation(s) in RCA: 71] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2017] [Revised: 08/16/2018] [Accepted: 08/20/2018] [Indexed: 12/11/2022]
Affiliation(s)
- Tanja Schulz-Mirbach
- Department Biology II, Zoology; Ludwig-Maximilians-University; Großhaderner Strasse 2, 82152 Planegg-Martinsried Germany
| | - Friedrich Ladich
- Department of Behavioural Biology; University of Vienna; Althanstrasse 14, 1090 Vienna Austria
| | - Martin Plath
- College of Animal Science & Technology; Northwest A&F University; 22 Xinong Road, Yangling Shaanxi China
| | - Martin Heß
- Department Biology II, Zoology; Ludwig-Maximilians-University; Großhaderner Strasse 2, 82152 Planegg-Martinsried Germany
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7
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Schlupp I. Male mate choice in livebearing fishes: an overview. Curr Zool 2018; 64:393-403. [PMID: 30402080 PMCID: PMC6007348 DOI: 10.1093/cz/zoy028] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2017] [Accepted: 04/01/2018] [Indexed: 12/12/2022] Open
Abstract
Although the majority of studies on mate choice focus on female mate choice, there is growing recognition of the role of male mate choice too. Male mate choice is tightly linked to 2 other phenomena: female competition for males and ornamentation in females. In the current article, I review the existing literature on this in a group of fishes, Poeciliidae. In this group, male mate choice appears to be based on differences in female quality, especially female size, which is a proxy for fecundity. Some males also have to choose between heterospecific and conspecific females in the unusual mating system of the Amazon molly. In this case, they typically show a preference for conspecific females. Whereas male mate choice is relatively well documented for this family, female ornamentation and female competition are not.
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Affiliation(s)
- Ingo Schlupp
- Department of Biology, University of Oklahoma, 730 Van Vleet Oval, Norman, OK 73019, USA
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8
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Boyle R, Ehsanian R, Mofrad A, Popova Y, Varelas J. Morphology of the utricular otolith organ in the toadfish, Opsanus tau. J Comp Neurol 2018. [PMID: 29524209 DOI: 10.1002/cne.24429] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
The utricle provides the vestibular reflex pathways with the sensory codes of inertial acceleration of self-motion and head orientation with respect to gravity to control balance and equilibrium. Here we present an anatomical description of this structure in the adult oyster toadfish and establish a morphological basis for interpretation of subsequent functional studies. Light, scanning, and transmission electron microscopy techniques were applied to visualize the sensory epithelium at varying levels of detail, its neural innervation and its synaptic organization. Scanning electron microscopy was used to visualize otolith mass and morphological polarization patterns of hair cells. Afferent nerve fibers were visualized following labeling with biocytin, and light microscope images were used to make three-dimensional (3-D) reconstructions of individual labeled afferents to identify dendritic morphology with respect to epithelial location. Transmission electron micrographs were compiled to create a serial 3-D reconstruction of a labeled afferent over a segment of its dendritic field and to examine the cell-afferent synaptic contacts. Major observations are: a well-defined striola, medial and lateral extra-striolar regions with a zonal organization of hair bundles; prominent lacinia projecting laterally; dependence of hair cell density on macular location; narrow afferent dendritic fields that follow the hair bundle polarization; synaptic specializations issued by afferents are typically directed towards a limited number of 7-13 hair cells, but larger dendritic fields in the medial extra-striola can be associated with > 20 hair cells also; and hair cell synaptic bodies can be confined to only an individual afferent or can synapse upon several afferents.
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Affiliation(s)
- Richard Boyle
- Vestibular Biophysics Laboratory, Ames Research Center, NASA, Moffett Field, California, 94035-1000
| | - Reza Ehsanian
- Vestibular Biophysics Laboratory, Ames Research Center, NASA, Moffett Field, California, 94035-1000
| | - Alireza Mofrad
- Vestibular Biophysics Laboratory, Ames Research Center, NASA, Moffett Field, California, 94035-1000
| | - Yekaterina Popova
- Vestibular Biophysics Laboratory, Ames Research Center, NASA, Moffett Field, California, 94035-1000
| | - Joseph Varelas
- Vestibular Biophysics Laboratory, Ames Research Center, NASA, Moffett Field, California, 94035-1000.,University of California, Santa Cruz, California, 95064
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9
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Ladich F, Schulz-Mirbach T. Diversity in Fish Auditory Systems: One of the Riddles of Sensory Biology. Front Ecol Evol 2016. [DOI: 10.3389/fevo.2016.00028] [Citation(s) in RCA: 58] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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10
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Schulz-Mirbach T, Ladich F. Diversity of Inner Ears in Fishes: Possible Contribution Towards Hearing Improvements and Evolutionary Considerations. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2016; 877:341-91. [DOI: 10.1007/978-3-319-21059-9_16] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/03/2022]
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11
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Soares D, Niemiller ML, Higgs DM. Hearing in Cavefishes. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2016; 877:187-95. [PMID: 26515315 DOI: 10.1007/978-3-319-21059-9_9] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Caves and associated subterranean habitats represent some of the harshest environments on Earth, yet many organisms, including fishes, have colonized and thrive in these habitats despite the complete absence of light, and other abiotic and biotic constraints. Over 170 species of fishes are considered obligate subterranean inhabitants (stygobionts) that exhibit some degree of troglomorphy, including degeneration of eyes and reduction in pigmentation. To compensate for lack of vision, many species have evolved constructive changes to non-visual sensory modalities. In this chapter we review hearing in cavefishes, with particular emphasize on our own studies on amblyopsid cavefishes. Hearing in cavefishes has not been well studied to date, as hearing ability has only been examined in four species. Two species show no differences in hearing ability relative to their surface relatives, while the other two species (family Amblyopsidae) exhibit regression in the form of reduced hearing range and reduction in hair cell densities on sensory epithelia. In addition to reviewing our current knowledge on cavefish hearing, we offer suggestions for future avenues of research on cavefish hearing and discuss the influence of Popper and Fay on the field of cavefish bioacoustics.
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Affiliation(s)
- Daphne Soares
- Biological Sciences, New Jersey Institute of Technology, Newark, NJ, 07102, USA.
| | - Matthew L Niemiller
- Illinois Natural History Survey, University of Illinois, Champaign, IL, 61820, USA
| | - Dennis M Higgs
- Biological Sciences, University of Windsor, Windsor, ON, Canada, N9B 3P4
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12
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Reichenbacher B, Reichard M. Otoliths of five extant species of the annual killifish Nothobranchius from the East African savannah. PLoS One 2014; 9:e112459. [PMID: 25383789 PMCID: PMC4226545 DOI: 10.1371/journal.pone.0112459] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2014] [Accepted: 10/15/2014] [Indexed: 01/17/2023] Open
Abstract
This study presents, for the first time, a comprehensive dataset that documents the range of inter- and intraspecific otolith variation in aplocheiloid killifish, based on a total of 86 individuals representing five extant species of Nothobranchius PETERS, 1868, from East Africa: the sympatric pairs N. rubripinnis SEEGERS, 1986 and N. ruudwildekampi COSTA, 2009 (Eastern Tanzania), and N. orthonotus (PETERS, 1844) and N. furzeri JUBB, 1971 (Southern Mozambique), and two isolated populations of N. korthausae MEINKEN, 1973 (Eastern Tanzania). Otolith characters were analysed based on SEM images, and otolith morphometry was conducted using uni- and multivariate statistics. Two ancient clades of probably Early to Middle Miocene age in eastern Tanzania and southern Mozambique can be recognized based on otolith morphologies, which is consistent with previous work based on molecular data. The distinctive sulcus morphologies in the otoliths of sympatric species may be linked to species-specific hearing capabilities, perhaps constituting a case of character displacement in an area of secondary sympatry. The otoliths of the studied species of Nothobranchius are diagnostic at the species level, even in the case of closely related species diagnosable otherwise only by minor differences in coloration. The two populations of N. korthausae also displayed some differences in their otolith characters. The new data may facilitate future recognition of fossil species of Nothobranchius. As no fossil remains of extant aplocheiloid killifishes have yet been described, the discovery of fossil otoliths of Nothobranchius would significantly advance understanding of the evolutionary history of this interesting group of fishes.
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Affiliation(s)
- Bettina Reichenbacher
- Department of Earth and Environmental Sciences, Palaeontology & Geobiology, Ludwig-Maximilians-University, Munich, Germany
| | - Martin Reichard
- Institute of Vertebrate Biology, Academy of Sciences of the Czech Republic, Brno, Czech Republic
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13
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Schulz-Mirbach T, Ladich F, Plath M, Metscher BD, Heß M. Are accessory hearing structures linked to inner ear morphology? Insights from 3D orientation patterns of ciliary bundles in three cichlid species. Front Zool 2014; 11:25. [PMID: 24645675 PMCID: PMC3999956 DOI: 10.1186/1742-9994-11-25] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2014] [Accepted: 02/27/2014] [Indexed: 11/26/2022] Open
Abstract
Background Cichlid fishes show considerable diversity in swim bladder morphology. In members of the subfamily Etroplinae, the connection between anterior swim bladder extensions and the inner ears enhances sound transmission and translates into an improved hearing ability. We tested the hypothesis that those swim bladder modifications coincide with differences in inner ear morphology and thus compared Steatocranus tinanti (vestigial swim bladder), Hemichromis guttatus (large swim bladder without extensions), and Etroplus maculatus (intimate connection between swim bladder and inner ears). Methodology and results We applied immunostaining together with confocal imaging and scanning electron microscopy for the investigation of sensory epithelia, and high-resolution, contrast-enhanced microCT imaging for characterizing inner ears in 3D, and evaluated otolith dimensions. Compared to S. tinanti and H. guttatus, inner ears of E. maculatus showed an enlargement of all three maculae, and a particularly large lacinia of the macula utriculi. While our analysis of orientation patterns of ciliary bundles on the three macula types using artificially flattened maculae uncovered rather similar orientation patterns of ciliary bundles, interspecific differences became apparent when illustrating the orientation patterns on the 3D models of the maculae: differences in the shape and curvature of the lacinia of the macula utriculi, and the anterior arm of the macula lagenae resulted in an altered arrangement of ciliary bundles. Conclusions Our results imply that improved audition in E. maculatus is associated not only with swim bladder modifications but also with altered inner ear morphology. However, not all modifications in E. maculatus could be connected to enhanced auditory abilities, and so a potential improvement of the vestibular sense, among others, also needs to be considered. Our study highlights the value of analyzing orientation patterns of ciliary bundles in their intact 3D context in studies of inner ear morphology and physiology.
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Affiliation(s)
- Tanja Schulz-Mirbach
- Department Biology II, Zoology, Ludwig-Maximilians-University, Martinsried, Germany.
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14
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Schulz-Mirbach T, Heß M, Metscher BD. Sensory epithelia of the fish inner ear in 3D: studied with high-resolution contrast enhanced microCT. Front Zool 2013; 10:63. [PMID: 24160754 PMCID: PMC4177137 DOI: 10.1186/1742-9994-10-63] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2013] [Accepted: 10/21/2013] [Indexed: 11/10/2022] Open
Abstract
Introduction While a number of studies have illustrated and analyzed 3D models of inner ears in higher vertebrates, inner ears in fishes have rarely been investigated in 3D, especially with regard to the sensory epithelia of the end organs, the maculae. It has been suggested that the 3D curvature of these maculae may also play an important role in hearing abilities in fishes. We therefore set out to develop a fast and reliable approach for detailed 3D visualization of whole inner ears as well as maculae. Results High-resolution microCT imaging of black mollies Poecilia sp. (Poeciliidae, Teleostei) and Steatocranus tinanti (Cichlidae, Teleostei) stained with phosphotungstic acid (PTA) resulted in good tissue contrast, enabling us to perform a reliable 3D reconstruction of all three sensory maculae of the inner ears. Comparison with maculae that have been 3D reconstructed based on histological serial sections and phalloidin-stained maculae showed high congruence in overall shape of the maculae studied here. Conclusions PTA staining and subsequent high-resolution contrast enhanced microCT imaging is a powerful method to obtain 3D models of fish inner ears and maculae in a fast and more reliable manner. Future studies investigating functional morphology, phylogenetic potential of inner ear features, or evolution of hearing and inner ear specialization in fishes may benefit from the use of 3D models of inner ears and maculae.
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Affiliation(s)
- Tanja Schulz-Mirbach
- Department of Biology II, Zoology, Ludwig-Maximilians-University, Martinsried, Germany.
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15
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Rüschenbaum S, Schlupp I. Non-Visual Mate Choice Ability in a Cavefish (Poecilia mexicana) is not Mechanosensory. Ethology 2013. [DOI: 10.1111/eth.12072] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Affiliation(s)
| | - Ingo Schlupp
- Department of Biology; University of Oklahoma; Norman; OK; USA
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