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De Vreese S, Orekhova K, Morell M, Gerussi T, Graïc JM. Neuroanatomy of the Cetacean Sensory Systems. Animals (Basel) 2023; 14:66. [PMID: 38200796 PMCID: PMC10778493 DOI: 10.3390/ani14010066] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2023] [Revised: 11/10/2023] [Accepted: 12/21/2023] [Indexed: 01/12/2024] Open
Abstract
Cetaceans have undergone profound sensory adaptations in response to their aquatic environment during evolution. These adaptations are characterised by anatomo-functional changes in the classically defined sensory systems, shaping their neuroanatomy accordingly. This review offers a concise and up-to-date overview of our current understanding of the neuroanatomy associated with cetacean sensory systems. It encompasses a wide spectrum, ranging from the peripheral sensory cells responsible for detecting environmental cues, to the intricate structures within the central nervous system that process and interpret sensory information. Despite considerable progress in this field, numerous knowledge gaps persist, impeding a comprehensive and integrated understanding of their sensory adaptations, and through them, of their sensory perspective. By synthesising recent advances in neuroanatomical research, this review aims to shed light on the intricate sensory alterations that differentiate cetaceans from other mammals and allow them to thrive in the marine environment. Furthermore, it highlights pertinent knowledge gaps and invites future investigations to deepen our understanding of the complex processes in cetacean sensory ecology and anatomy, physiology and pathology in the scope of conservation biology.
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Affiliation(s)
- Steffen De Vreese
- Laboratory of Applied Bioacoustics (LAB), Universitat Politècnica de Catalunya-BarcelonaTech (UPC), 08800 Vilanova i la Geltrú, Spain
| | - Ksenia Orekhova
- Department of Comparative Biomedicine and Food Science (BCA), University of Padova, 35020 Legnaro, Italy; (K.O.); (T.G.); (J.-M.G.)
| | - Maria Morell
- Institute for Terrestrial and Aquatic Wildlife Research (ITAW), University of Veterinary Medicine Hannover, Foundation, 25761 Büsum, Germany;
| | - Tommaso Gerussi
- Department of Comparative Biomedicine and Food Science (BCA), University of Padova, 35020 Legnaro, Italy; (K.O.); (T.G.); (J.-M.G.)
| | - Jean-Marie Graïc
- Department of Comparative Biomedicine and Food Science (BCA), University of Padova, 35020 Legnaro, Italy; (K.O.); (T.G.); (J.-M.G.)
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2
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Liu Q, Zhang X, Huang H, Chen Y, Wang F, Hao A, Zhan W, Mao Q, Hu Y, Han L, Sun Y, Zhang M, Liu Z, Li GL, Zhang W, Shu Y, Sun L, Chen Z. Asymmetric pendrin homodimer reveals its molecular mechanism as anion exchanger. Nat Commun 2023; 14:3012. [PMID: 37230976 DOI: 10.1038/s41467-023-38303-0] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2022] [Accepted: 04/23/2023] [Indexed: 05/27/2023] Open
Abstract
Pendrin (SLC26A4) is an anion exchanger expressed in the apical membranes of selected epithelia. Pendrin ablation causes Pendred syndrome, a genetic disorder associated with sensorineural hearing loss, hypothyroid goiter, and reduced blood pressure. However its molecular structure has remained unknown, limiting our understanding of the structural basis of transport. Here, we determine the cryo-electron microscopy structures of mouse pendrin with symmetric and asymmetric homodimer conformations. The asymmetric homodimer consists of one inward-facing protomer and the other outward-facing protomer, representing coincident uptake and secretion- a unique state of pendrin as an electroneutral exchanger. The multiple conformations presented here provide an inverted alternate-access mechanism for anion exchange. The structural and functional data presented here disclose the properties of an anion exchange cleft and help understand the importance of disease-associated variants, which will shed light on the pendrin exchange mechanism.
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Affiliation(s)
- Qianying Liu
- The Fifth People's Hospital of Shanghai and Institutes of Biomedical Sciences, Fudan University, Shanghai, 200032, China
| | - Xiang Zhang
- The Fifth People's Hospital of Shanghai and Institutes of Biomedical Sciences, Fudan University, Shanghai, 200032, China
| | - Hui Huang
- The Fifth People's Hospital of Shanghai and Institutes of Biomedical Sciences, Fudan University, Shanghai, 200032, China
| | - Yuxin Chen
- ENT Institute and Department of Otorhinolaryngology, Eye & ENT Hospital and State Key Laboratory of Medical Neurobiology, Fudan University, Shanghai, 200031, China
- MOE Frontiers Center for Brain Science, Fudan University, Shanghai, 200031, China
- NHC Key Laboratory of Hearing Medicine, Fudan University, Shanghai, 200031, China
| | - Fang Wang
- ENT Institute and Department of Otorhinolaryngology, Eye & ENT Hospital and State Key Laboratory of Medical Neurobiology, Fudan University, Shanghai, 200031, China
- MOE Frontiers Center for Brain Science, Fudan University, Shanghai, 200031, China
- NHC Key Laboratory of Hearing Medicine, Fudan University, Shanghai, 200031, China
| | - Aihua Hao
- The Fifth People's Hospital of Shanghai and Institutes of Biomedical Sciences, Fudan University, Shanghai, 200032, China
| | - Wuqiang Zhan
- The Fifth People's Hospital of Shanghai and Institutes of Biomedical Sciences, Fudan University, Shanghai, 200032, China
| | - Qiyu Mao
- The Fifth People's Hospital of Shanghai and Institutes of Biomedical Sciences, Fudan University, Shanghai, 200032, China
| | - Yuxia Hu
- The Fifth People's Hospital of Shanghai and Institutes of Biomedical Sciences, Fudan University, Shanghai, 200032, China
| | - Lin Han
- The Fifth People's Hospital of Shanghai and Institutes of Biomedical Sciences, Fudan University, Shanghai, 200032, China
| | - Yifang Sun
- The Fifth People's Hospital of Shanghai and Institutes of Biomedical Sciences, Fudan University, Shanghai, 200032, China
| | - Meng Zhang
- The Fifth People's Hospital of Shanghai and Institutes of Biomedical Sciences, Fudan University, Shanghai, 200032, China
| | - Zhimin Liu
- The Fifth People's Hospital of Shanghai and Institutes of Biomedical Sciences, Fudan University, Shanghai, 200032, China
| | - Geng-Lin Li
- ENT Institute and Department of Otorhinolaryngology, Eye & ENT Hospital and State Key Laboratory of Medical Neurobiology, Fudan University, Shanghai, 200031, China
- MOE Frontiers Center for Brain Science, Fudan University, Shanghai, 200031, China
- NHC Key Laboratory of Hearing Medicine, Fudan University, Shanghai, 200031, China
| | - Weijia Zhang
- The Fifth People's Hospital of Shanghai and Institutes of Biomedical Sciences, Fudan University, Shanghai, 200032, China
| | - Yilai Shu
- ENT Institute and Department of Otorhinolaryngology, Eye & ENT Hospital and State Key Laboratory of Medical Neurobiology, Fudan University, Shanghai, 200031, China.
- MOE Frontiers Center for Brain Science, Fudan University, Shanghai, 200031, China.
- NHC Key Laboratory of Hearing Medicine, Fudan University, Shanghai, 200031, China.
- Institutes of Biomedical Sciences, Fudan University, Shanghai, 200032, China.
| | - Lei Sun
- The Fifth People's Hospital of Shanghai and Institutes of Biomedical Sciences, Fudan University, Shanghai, 200032, China.
- Shanghai Institute of Infectious Disease and Biosecurity, Shanghai, 200032, China.
- Shanghai Key Laboratory of Medical Epigenetics, Shanghai, 200032, China.
| | - Zhenguo Chen
- The Fifth People's Hospital of Shanghai and Institutes of Biomedical Sciences, Fudan University, Shanghai, 200032, China.
- Shanghai Institute of Infectious Disease and Biosecurity, Shanghai, 200032, China.
- Shanghai Key Laboratory of Medical Epigenetics, Shanghai, 200032, China.
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3
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Morell M, IJsseldijk LL, Berends AJ, Gröne A, Siebert U, Raverty SA, Shadwick RE, Kik MJL. Evidence of Hearing Loss and Unrelated Toxoplasmosis in a Free-Ranging Harbour Porpoise ( Phocoena phocoena). Animals (Basel) 2021; 11:ani11113058. [PMID: 34827790 PMCID: PMC8614470 DOI: 10.3390/ani11113058] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2021] [Accepted: 10/20/2021] [Indexed: 01/09/2023] Open
Abstract
Simple Summary Evidence of hearing impairment was identified in a female harbour porpoise (Phocoena phocoena) on the basis of inner ear analysis. The animal live stranded on the Dutch coast at Domburg in 2016 and died a few hours later. Ultrastructural examination of the inner ear revealed evidence of sensory cell loss, which is compatible with noise exposure. In addition, histopathology also revealed multifocal necrotising protozoal encephalitis. A diagnosis of toxoplasmosis was confirmed by positive staining of tissue with anti-Toxoplasma gondii antibodies; however, T. gondii tachyzoites were not observed histologically in any of the examined tissues. This is the first case of presumptive noise-induced hearing loss and demonstration of T. gondii cysts in the brain of a free-ranging harbour porpoise from the North Sea. Abstract Evidence of hearing impairment was identified in a harbour porpoise (Phocoena phocoena) on the basis of scanning electron microscopy. In addition, based on histopathology and immunohistochemistry, there were signs of unrelated cerebral toxoplasmosis. The six-year old individual live stranded on the Dutch coast at Domburg in 2016 and died a few hours later. The most significant gross lesion was multifocal necrosis and haemorrhage of the cerebrum. Histopathology of the brain revealed extensive necrosis and haemorrhage in the cerebrum with multifocal accumulations of degenerated neutrophils, lymphocytes and macrophages, and perivascular lymphocytic cuffing. The diagnosis of cerebral toxoplasmosis was confirmed by positive staining of protozoa with anti-Toxoplasma gondii antibodies. Tachyzoites were not observed histologically in any of the examined tissues. Ultrastructural evaluation of the inner ear revealed evidence of scattered loss of outer hair cells in a 290 µm long segment of the apical turn of the cochlea, and in a focal region of ~ 1.5 mm from the apex of the cochlea, which was compatible with noise-induced hearing loss. This is the first case of concurrent presumptive noise-induced hearing loss and toxoplasmosis in a free-ranging harbour porpoise from the North Sea.
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Affiliation(s)
- Maria Morell
- Institute for Terrestrial and Aquatic Wildlife Research, University of Veterinary Medicine Hannover, Foundation, 25761 Büsum, Germany;
- Zoology Department, The University of British Columbia, Vancouver, BC V6T 1Z4, Canada; (S.A.R.); (R.E.S.)
- Correspondence: (M.M.); (L.L.I.)
| | - Lonneke L. IJsseldijk
- Department of Biomolecular Health Sciences, Division of Pathology, Faculty of Veterinary Medicine, Utrecht University, 3584 CL Utrecht, The Netherlands; (A.J.B.); (A.G.); (M.J.L.K.)
- Correspondence: (M.M.); (L.L.I.)
| | - Alinda J. Berends
- Department of Biomolecular Health Sciences, Division of Pathology, Faculty of Veterinary Medicine, Utrecht University, 3584 CL Utrecht, The Netherlands; (A.J.B.); (A.G.); (M.J.L.K.)
| | - Andrea Gröne
- Department of Biomolecular Health Sciences, Division of Pathology, Faculty of Veterinary Medicine, Utrecht University, 3584 CL Utrecht, The Netherlands; (A.J.B.); (A.G.); (M.J.L.K.)
| | - Ursula Siebert
- Institute for Terrestrial and Aquatic Wildlife Research, University of Veterinary Medicine Hannover, Foundation, 25761 Büsum, Germany;
| | - Stephen A. Raverty
- Zoology Department, The University of British Columbia, Vancouver, BC V6T 1Z4, Canada; (S.A.R.); (R.E.S.)
- Animal Health Center, Ministry of Agriculture, Abbotsford, BC V3G 2M3, Canada
| | - Robert E. Shadwick
- Zoology Department, The University of British Columbia, Vancouver, BC V6T 1Z4, Canada; (S.A.R.); (R.E.S.)
| | - Marja J. L. Kik
- Department of Biomolecular Health Sciences, Division of Pathology, Faculty of Veterinary Medicine, Utrecht University, 3584 CL Utrecht, The Netherlands; (A.J.B.); (A.G.); (M.J.L.K.)
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Neurotoxic Effects of Neonicotinoids on Mammals: What Is There beyond the Activation of Nicotinic Acetylcholine Receptors?-A Systematic Review. Int J Mol Sci 2021; 22:ijms22168413. [PMID: 34445117 PMCID: PMC8395098 DOI: 10.3390/ijms22168413] [Citation(s) in RCA: 35] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2021] [Revised: 07/29/2021] [Accepted: 08/02/2021] [Indexed: 02/07/2023] Open
Abstract
Neonicotinoids are a class of insecticides that exert their effect through a specific action on neuronal nicotinic acetylcholine receptors (nAChRs). The success of these insecticides is due to this mechanism of action, since they act as potent agonists of insect nAChRs, presenting low affinity for vertebrate nAChRs, which reduces potential toxic risk and increases safety for non-target species. However, although neonicotinoids are considered safe, their presence in the environment could increase the risk of exposure and toxicity. On the other hand, although neonicotinoids have low affinity for mammalian nAChRs, the large quantity, variety, and ubiquity of these receptors, combined with its diversity of functions, raises the question of what effects these insecticides can produce in non-target species. In the present systematic review, we investigate the available evidence on the biochemical and behavioral effects of neonicotinoids on the mammalian nervous system. In general, exposure to neonicotinoids at an early age alters the correct neuronal development, with decreases in neurogenesis and alterations in migration, and induces neuroinflammation. In adulthood, neonicotinoids induce neurobehavioral toxicity, these effects being associated with their modulating action on nAChRs, with consequent neurochemical alterations. These alterations include decreased expression of nAChRs, modifications in acetylcholinesterase activity, and significant changes in the function of the nigrostriatal dopaminergic system. All these effects can lead to the activation of a series of intracellular signaling pathways that generate oxidative stress, neuroinflammation and, finally, neuronal death. Neonicotinoid-induced changes in nAChR function could be responsible for most of the effects observed in the different studies.
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Morell M, IJsseldijk LL, Piscitelli-Doshkov M, Ostertag S, Estrade V, Haulena M, Doshkov P, Bourien J, Raverty SA, Siebert U, Puel JL, Shadwick RE. Cochlear apical morphology in toothed whales: Using the pairing hair cell-Deiters' cell as a marker to detect lesions. Anat Rec (Hoboken) 2021; 305:622-642. [PMID: 34096183 DOI: 10.1002/ar.24680] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2020] [Revised: 03/17/2021] [Accepted: 04/15/2021] [Indexed: 11/06/2022]
Abstract
The apex or apical region of the cochlear spiral within the inner ear encodes for low-frequency sounds. The disposition of sensory hair cells on the organ of Corti is largely variable in the apical region of mammals, and it does not necessarily follow the typical three-row pattern of outer hair cells (OHCs). As most underwater noise sources contain low-frequency components, we expect to find most lesions in the apical region of the cochlea of toothed whales, in cases of permanent noise-induced hearing loss. To further understand how man-made noise might affect cetacean hearing, there is a need to describe normal morphological features of the apex and document interspecific anatomic variations in cetaceans. However, distinguishing between apical normal variability and hair cell death is challenging. We describe anatomical features of the organ of Corti of the apex in 23 ears from five species of toothed whales (harbor porpoise Phocoena phocoena, spinner dolphin Stenella longirostris, pantropical spotted dolphin Stenella attenuata, pygmy sperm whale Kogia breviceps, and beluga whale Delphinapterus leucas) by scanning electron microscopy and immunofluorescence. Our results showed an initial region where the lowest frequencies are encoded with two or three rows of OHCs, followed by the typical configuration of three OHC rows and three rows of supporting Deiters' cells. Whenever two rows of OHCs were detected, there were usually only two corresponding rows of supporting Deiters' cells, suggesting that the number of rows of Deiters' cells is a good indicator to distinguish between normal and pathological features.
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Affiliation(s)
- Maria Morell
- Institute for Terrestrial and Aquatic Wildlife Research, University of Veterinary Medicine Hannover, Foundation, Büsum, Germany.,Institute for Neurosciences of Montpellier, University of Montpellier, INSERM Unit 1051, Montpellier, France.,Department of Zoology, The University of British Columbia, Vancouver, British Columbia, Canada
| | - Lonneke L IJsseldijk
- Division of Pathology, Department of Biomolecular Health Sciences, Faculty of Veterinary Medicine, Utrecht University, Utrecht, The Netherlands
| | | | - Sonja Ostertag
- School of Public Health, University of Waterloo, Waterloo, Ontario, Canada.,Freshwater Institute, Fisheries and Oceans Canada, Winnipeg, Manitoba, Canada
| | | | - Martin Haulena
- Vancouver Aquarium Marine Science Center, Vancouver, British Columbia, Canada
| | - Paul Doshkov
- Cape Hatteras National Seashore, Manteo, North Carolina, USA
| | - Jérôme Bourien
- Institute for Neurosciences of Montpellier, University of Montpellier, INSERM Unit 1051, Montpellier, France
| | - Stephen A Raverty
- Department of Zoology, The University of British Columbia, Vancouver, British Columbia, Canada.,Animal Health Center, Animal Health Center, Ministry of Agriculture, Abbotsford, British Columbia, Canada
| | - Ursula Siebert
- Institute for Terrestrial and Aquatic Wildlife Research, University of Veterinary Medicine Hannover, Foundation, Büsum, Germany
| | - Jean-Luc Puel
- Institute for Neurosciences of Montpellier, University of Montpellier, INSERM Unit 1051, Montpellier, France
| | - Robert E Shadwick
- Department of Zoology, The University of British Columbia, Vancouver, British Columbia, Canada
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6
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Wang Z, Ma Q, Lu J, Cui X, Chen H, Wu H, Huang Z. Functional Parameters of Prestin Are Not Correlated With the Best Hearing Frequency. Front Cell Dev Biol 2021; 9:638530. [PMID: 34046403 PMCID: PMC8144510 DOI: 10.3389/fcell.2021.638530] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2020] [Accepted: 03/23/2021] [Indexed: 11/29/2022] Open
Abstract
Among the vertebrate lineages with different hearing frequency ranges, humans lie between the low-frequency hearing (1 kHz) of fish and amphibians and the high-frequency hearing (100 kHz) of bats and dolphins. Little is known about the mechanism underlying such a striking difference in the limits of hearing frequency. Prestin, responsible for cochlear amplification and frequency selectivity in mammals, seems to be the only candidate to date. Mammalian prestin is densely expressed in the lateral plasma membrane of the outer hair cells (OHCs) and functions as a voltage-dependent motor protein. To explore the molecular basis for the contribution of prestin in hearing frequency detection, we collected audiogram data from humans, dogs, gerbils, bats, and dolphins because their average hearing frequency rises in steps. We generated stable cell lines transfected with human, dog, gerbil, bat, and dolphin prestins (hPres, dPres, gPres, bPres, and nPres, respectively). The non-linear capacitance (NLC) of different prestins was measured using a whole-cell patch clamp. We found that the Qmax/Clin of bPres and nPres was significantly higher than that of humans. The V1/2 of hPres was more hyperpolarized than that of nPres. The z values of hPres and bPres were higher than that of nPres. We further analyzed the relationship between the high-frequency hearing limit (Fmax) and the functional parameters (V1/2, z, and Qmax/Clin) of NLC among five prestins. Interestingly, no significant correlation was found between the functional parameters and Fmax. Additionally, a comparative study showed that the amino acid sequences and tertiary structures of five prestins were quite similar. There might be a common fundamental mechanism driving the function of prestins. These findings call for a reconsideration of the leading role of prestin in hearing frequency perception. Other intriguing kinetics underlying the hearing frequency response of auditory organs might exist.
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Affiliation(s)
- Zhongying Wang
- Department of Otolaryngology-Head and Neck Surgery, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China.,Ear Institute, Shanghai Jiao Tong University School of Medicine, Shanghai, China.,Shanghai Key Laboratory of Translational Medicine on Ear and Nose Diseases, Shanghai, China
| | - Qingping Ma
- Department of Otolaryngology-Head and Neck Surgery, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China.,Ear Institute, Shanghai Jiao Tong University School of Medicine, Shanghai, China.,Shanghai Key Laboratory of Translational Medicine on Ear and Nose Diseases, Shanghai, China
| | - Jiawen Lu
- Department of Otolaryngology-Head and Neck Surgery, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China.,Ear Institute, Shanghai Jiao Tong University School of Medicine, Shanghai, China.,Shanghai Key Laboratory of Translational Medicine on Ear and Nose Diseases, Shanghai, China
| | - Xiaochen Cui
- State Key Laboratory of Microbial Metabolism, Joint International Research Laboratory of Metabolic and Developmental Sciences, Department of Bioinformatics and Biostatistics, National Experimental Teaching Center for Life Sciences and Biotechnology, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai, China
| | - Haifeng Chen
- State Key Laboratory of Microbial Metabolism, Joint International Research Laboratory of Metabolic and Developmental Sciences, Department of Bioinformatics and Biostatistics, National Experimental Teaching Center for Life Sciences and Biotechnology, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai, China.,Shanghai Center for Bioinformation Technology, Shanghai, China
| | - Hao Wu
- Department of Otolaryngology-Head and Neck Surgery, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China.,Ear Institute, Shanghai Jiao Tong University School of Medicine, Shanghai, China.,Shanghai Key Laboratory of Translational Medicine on Ear and Nose Diseases, Shanghai, China
| | - Zhiwu Huang
- Department of Otolaryngology-Head and Neck Surgery, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China.,Ear Institute, Shanghai Jiao Tong University School of Medicine, Shanghai, China.,Shanghai Key Laboratory of Translational Medicine on Ear and Nose Diseases, Shanghai, China
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7
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IJsseldijk LL, Scheidat M, Siemensma ML, Couperus B, Leopold MF, Morell M, Gröne A, Kik MJL. Challenges in the Assessment of Bycatch: Postmortem Findings in Harbor Porpoises ( Phocoena phocoena) Retrieved From Gillnets. Vet Pathol 2021; 58:405-415. [PMID: 33272139 PMCID: PMC7961740 DOI: 10.1177/0300985820972454] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Bycatch is considered one of the most significant threats affecting cetaceans worldwide. In the North Sea, bottom-set gillnets are a specific risk for harbor porpoises (Phocoena phocoena). Methods to estimate bycatch rates include on-board observers, remote electronic monitoring, and fishermen voluntarily reporting; none of these are systematically conducted. Additionally, necropsies of stranded animals can provide insights into bycatch occurrence and health status of individuals. There are, however, uncertainties when it comes to the assessment of bycatch in stranded animals, mainly due to the lack of diagnostic tools specific for underwater entrapment. We conducted a literature review to establish criteria that aid in the assessment of bycatch in small cetaceans, and we tested which of these criteria applied to harbor porpoises retrieved from gillnets in the Netherlands (n = 12). Twenty-five criteria were gathered from literature. Of these, "superficial incisions," "encircling imprints," and "recent ingestion of prey" were observed in the vast majority of our confirmed bycatch cases. Criteria like "pulmonary edema," "pulmonary emphysema," and "organ congestion" were also frequently observed, although considered unspecific as an indicator of bycatch. Notably, previously mentioned criteria as "favorable health status," "absence of disease," or "good nutritional condition" did not apply to the majority of our bycaught porpoises. This may reflect an overall reduced fitness of harbor porpoises inhabiting the southern North Sea or a higher chance of a debilitated porpoise being bycaught, and could result in an underestimation of bycatch rates when assessing stranded animals.
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Affiliation(s)
- Lonneke L. IJsseldijk
- Division of Pathology, Department of Biomolecular Health Sciences, Faculty of Veterinary Medicine, Utrecht University, The Netherlands
| | | | | | - Bram Couperus
- Wageningen Marine Research, Ijmuiden, the Netherlands
| | | | - Maria Morell
- Institute for Terrestrial and Aquatic Wildlife Research, University of Veterinary Medicine Hannover, Büsum, Germany
| | - Andrea Gröne
- Division of Pathology, Department of Biomolecular Health Sciences, Faculty of Veterinary Medicine, Utrecht University, The Netherlands
| | - Marja J. L. Kik
- Division of Pathology, Department of Biomolecular Health Sciences, Faculty of Veterinary Medicine, Utrecht University, The Netherlands
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8
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Morell M, Raverty SA, Mulsow J, Haulena M, Barrett-Lennard L, Nordstrom CA, Venail F, Shadwick RE. Combining Cochlear Analysis and Auditory Evoked Potentials in a Beluga Whale With High-Frequency Hearing Loss. Front Vet Sci 2020; 7:534917. [PMID: 33330679 PMCID: PMC7672125 DOI: 10.3389/fvets.2020.534917] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2020] [Accepted: 10/05/2020] [Indexed: 11/21/2022] Open
Abstract
Correlations between inner ear morphology and auditory sensitivity in the same individual are extremely difficult to obtain for stranded cetaceans. Animals in captivity and rehabilitation offer the opportunity to combine several techniques to study the auditory system and cases of hearing impairment in a controlled environment. Morphologic and auditory findings from two beluga whales (Delphinapterus leucas) in managed care are presented. Cochlear analysis of a 21-year-old beluga whale showed bilateral high-frequency hearing loss. Specifically, scanning electron microscopy of the left ear revealed sensory cell death in the first 4.9 mm of the base of the cochlea with scar formation. Immunofluorescence microscopy of the right ear confirmed the absence of hair cells and type I afferent innervation in the first 6.6 mm of the base of the cochlea, most likely due to an ischemia. Auditory evoked potentials (AEPs) measured 1.5 years prior this beluga's death showed a generalized hearing loss, being more pronounced in the high frequencies. This individual might have had a mixed hearing loss that would explain the generalized hearing impairment. Conversely, based on AEP evaluation, her mother had normal hearing and subsequent cochlear analysis did not feature any apparent sensorineural pathology. This is believed to be the first study to compare two cochlear analysis techniques and hearing sensitivity measurements from AEPs in cetaceans. The ability to combine morphological and auditory data is crucial to validate predictions of cochlear frequency maps based on morphological features. In addition, our study shows that these three complementary analysis techniques lead to comparable results, thus improving our understanding of how hearing impairment can be detected in stranding cases.
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Affiliation(s)
- Maria Morell
- Zoology Department, The University of British Columbia, Vancouver, BC, Canada
- INSERM Unit 1051, Institute for Neurosciences of Montpellier, Montpellier, France
- Institute for Terrestrial and Aquatic Wildlife Research, University of Veterinary Medicine Hannover, Foundation, Büsum, Germany
| | - Stephen A. Raverty
- Zoology Department, The University of British Columbia, Vancouver, BC, Canada
- Animal Health Center, Ministry of Agriculture, Abbotsford, BC, Canada
| | - Jason Mulsow
- National Marine Mammal Foundation, San Diego, CA, United States
| | - Martin Haulena
- Vancouver Aquarium Marine Science Center, Vancouver, BC, Canada
| | | | - Chad A. Nordstrom
- Coastal Ocean Research Institute, Vancouver Aquarium, Vancouver, BC, Canada
- Fisheries and Oceans Canada, Pacific Biological Station, Nanaimo, BC, Canada
| | - Frederic Venail
- INSERM Unit 1051, Institute for Neurosciences of Montpellier, Montpellier, France
| | - Robert E. Shadwick
- Zoology Department, The University of British Columbia, Vancouver, BC, Canada
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