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Gyamfi S, Edziyie RE, Obirikorang KA, Adjei-Boateng D, Skov PV. Nile tilapia (Oreochromis niloticus) show high tolerance to acute ammonia exposure but lose metabolic scope during prolonged exposure at low concentration. AQUATIC TOXICOLOGY (AMSTERDAM, NETHERLANDS) 2024; 271:106932. [PMID: 38692129 DOI: 10.1016/j.aquatox.2024.106932] [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: 01/04/2024] [Revised: 04/23/2024] [Accepted: 04/24/2024] [Indexed: 05/03/2024]
Abstract
Ammonia is a respiratory gas that is produced during the process of protein deamination. In the unionised form (NH3), it readily crosses biological membranes and is highly toxic to fish. In the present study we examined the effects of unionized ammonia (UIA), on the resting oxygen consumption (MO2), ventilation frequency (fV), heart rate (HR) and heart rate variability (HRV) in Nile tilapia (Oreochromis niloticus). Fish were either exposed to progressively increasing UIA concentrations, up to 97 µM over a 5 h period, or to a constant UIA level of 7 µM over a 24 h period. For both treatment groups resting MO2, HR and fV were recorded as physiological variables. Relative to the control group, the fish groups exposed to the incremental UIA levels did not exhibit significant changes in their MO2, HR and fV at UIA concentrations of 4, 10, 35, or 61 µM compared to control fish. Exposure to 97 µM UIA, however, elicited abrupt and significant downregulations (p < 0.05) in all three responses, as MO2, HR and fv decreased by 25, 54 and 76 % respectively, compared to control measurements. Heart rate became increasingly irregular with increasing UIA concentrations, and heart rate variability was significantly increased at 61 and 97 µM UIA. Prolonged exposure elicited significant changes at exposure 7 µM UIA. Standard (SMR) and maximum metabolic rate (MMR) were significantly reduced, as was the corresponding fV and HR. It is evident from this study that Nile tilapia is tolerant to short term exposure to UIA up to 61 µM but experience a significant metabolic change under conditions of prolonged UIA exposures even at low concentrations.
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Affiliation(s)
- Stephen Gyamfi
- Kwame Nkrumah University of Science and Technology, Department of Fisheries and Watershed Management, Kumasi, Ghana
| | - Regina Esi Edziyie
- Kwame Nkrumah University of Science and Technology, Department of Fisheries and Watershed Management, Kumasi, Ghana
| | - Kwasi Adu Obirikorang
- Kwame Nkrumah University of Science and Technology, Department of Fisheries and Watershed Management, Kumasi, Ghana
| | - Daniel Adjei-Boateng
- Kwame Nkrumah University of Science and Technology, Department of Fisheries and Watershed Management, Kumasi, Ghana
| | - Peter Vilhelm Skov
- Technical University of Denmark, DTU Aqua, Section for Aquaculture, The North Sea Research Centre, Hirtshals, Denmark
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Tripathi A, Gayen T, Maitra P, Kumari U, Mittal S, Mittal AK. Assessment of triclosan induced histopathological and biochemical alterations, and molecular docking simulation analysis of acetylcholinesterase enzyme in the gills of fish, Cyprinus carpio. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2024; 31:41069-41083. [PMID: 38842779 DOI: 10.1007/s11356-024-33840-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/15/2023] [Accepted: 05/24/2024] [Indexed: 06/07/2024]
Abstract
Triclosan (TCS), an antimicrobial additive in various personal and health care products, has been widely detected in aquatic environment around the world. The present study investigated the impacts of TCS in the gills of the fish, Cyprinus carpio employing histopathological, biochemical, molecular docking and simulation analysis. The 96 h LC50 value of TCS in C. carpio was found to be 0.968 mg/L. Fish were exposed to 1/1000th (1 µg/L), 1/100th (10 µg/L), and 1/10th (100 µg/L) of 96 h LC50 value for a period of 28 days. The histopathological alterations observed in the gills were hypertrophy, hyperplasia, edematous swellings, and fusion of secondary lamellae in TCS exposed groups. The severity of these alterations increased with both the concentration as well as the duration of exposure. The present study revealed that the activity of antioxidant enzymes such as superoxide dismutase, catalase, glutathione-S-transferase, glutathione reductase, glutathione peroxidase, and reduced glutathione content decreased significantly (p < 0.05) in both concentration and duration dependent manner. However, a significant (p < 0.05) increase in the activity of the metabolic enzymes such as acid phosphatase and alkaline phosphatase was observed in all three exposure concentrations of TCS from 7 to 28 days. The activity of acetylcholinesterase declined significantly (p < 0.05) from 7 to 28 days whereas the content of acetylcholine increased significantly at the end of 28 day. The experimental results were further confirmed by molecular docking and simulation analysis that showed strong binding of TCS with acetylcholinesterase enzyme. The study revealed that long-term exposure to sublethal concentrations of TCS can lead to severe physiological and histopathological alterations in the fish.
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Affiliation(s)
- Anchal Tripathi
- Fish Physiology Laboratory, Zoology Section, Mahila Mahavidyalaya, Banaras Hindu University, Varanasi, 221 005, India
| | - Tuhina Gayen
- Fish Physiology Laboratory, Zoology Section, Mahila Mahavidyalaya, Banaras Hindu University, Varanasi, 221 005, India
| | - Priyasha Maitra
- Bioinformatics Programme, Mahila Mahavidyalaya, Banaras Hindu University, Varanasi, 221 005, India
| | - Usha Kumari
- Fish Physiology Laboratory, Zoology Section, Mahila Mahavidyalaya, Banaras Hindu University, Varanasi, 221 005, India.
| | - Swati Mittal
- Skin Physiology Laboratory, Department of Zoology, Institute of Science, Banaras Hindu University, Varanasi, 221 005, India
| | - Ajay Kumar Mittal
- Department of Zoology, Banaras Hindu University, 9, Mani Nagar, Kandawa, Varanasi, 221106, India
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Brown TL, Horton EC, Craig EW, Goo CEA, Black EC, Hewitt MN, Yee NG, Fan ET, Raible DW, Rasmussen JP. Dermal appendage-dependent patterning of zebrafish atoh1a+ Merkel cells. eLife 2023; 12:85800. [PMID: 36648063 PMCID: PMC9901935 DOI: 10.7554/elife.85800] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2022] [Accepted: 01/11/2023] [Indexed: 01/18/2023] Open
Abstract
Touch system function requires precise interactions between specialized skin cells and somatosensory axons, as exemplified by the vertebrate mechanosensory Merkel cell-neurite complex. Development and patterning of Merkel cells and associated neurites during skin organogenesis remain poorly understood, partly due to the in utero development of mammalian embryos. Here, we discover Merkel cells in the zebrafish epidermis and identify Atonal homolog 1a (Atoh1a) as a marker of zebrafish Merkel cells. We show that zebrafish Merkel cells derive from basal keratinocytes, express neurosecretory and mechanosensory machinery, extend actin-rich microvilli, and complex with somatosensory axons, all hallmarks of mammalian Merkel cells. Merkel cells populate all major adult skin compartments, with region-specific densities and distribution patterns. In vivo photoconversion reveals that Merkel cells undergo steady loss and replenishment during skin homeostasis. Merkel cells develop concomitant with dermal appendages along the trunk and loss of Ectodysplasin signaling, which prevents dermal appendage formation, reduces Merkel cell density by affecting cell differentiation. By contrast, altering dermal appendage morphology changes the distribution, but not density, of Merkel cells. Overall, our studies provide insights into touch system maturation during skin organogenesis and establish zebrafish as an experimentally accessible in vivo model for the study of Merkel cell biology.
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Affiliation(s)
- Tanya L Brown
- Department of Biology, University of WashingtonSeattleUnited States
| | - Emma C Horton
- Department of Biology, University of WashingtonSeattleUnited States
| | - Evan W Craig
- Department of Biology, University of WashingtonSeattleUnited States
| | - Camille EA Goo
- Department of Biology, University of WashingtonSeattleUnited States
| | - Erik C Black
- Department of Biology, University of WashingtonSeattleUnited States
- Molecular and Cellular Biology Program, University of WashingtonSeattleUnited States
| | - Madeleine N Hewitt
- Molecular and Cellular Biology Program, University of WashingtonSeattleUnited States
- Department of Biological Structure, University of WashingtonSeattleUnited States
| | - Nathaniel G Yee
- Department of Biology, University of WashingtonSeattleUnited States
| | - Everett T Fan
- Department of Biology, University of WashingtonSeattleUnited States
| | - David W Raible
- Department of Biological Structure, University of WashingtonSeattleUnited States
- Department of Otolaryngology - Head and Neck Surgery, University of WashingtonSeattleUnited States
- Institute for Stem Cell and Regenerative Medicine, University of WashingtonSeattleUnited States
| | - Jeffrey P Rasmussen
- Department of Biology, University of WashingtonSeattleUnited States
- Institute for Stem Cell and Regenerative Medicine, University of WashingtonSeattleUnited States
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Expression of the Antimicrobial Peptide Piscidin 1 and Neuropeptides in Fish Gill and Skin: A Potential Participation in Neuro-Immune Interaction. Mar Drugs 2022; 20:md20020145. [PMID: 35200674 PMCID: PMC8879440 DOI: 10.3390/md20020145] [Citation(s) in RCA: 16] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2022] [Revised: 02/09/2022] [Accepted: 02/14/2022] [Indexed: 12/12/2022] Open
Abstract
Antimicrobial peptides (AMPs) are found widespread in nature and possess antimicrobial and immunomodulatory activities. Due to their multifunctional properties, these peptides are a focus of growing body of interest and have been characterized in several fish species. Due to their similarities in amino-acid composition and amphipathic design, it has been suggested that neuropeptides may be directly involved in the innate immune response against pathogen intruders. In this review, we report the molecular characterization of the fish-specific AMP piscidin1, the production of an antibody raised against this peptide and the immunohistochemical identification of this peptide and enkephalins in the neuroepithelial cells (NECs) in the gill of several teleost fish species living in different habitats. In spite of the abundant literature on Piscidin1, the biological role of this peptide in fish visceral organs remains poorly explored, as well as the role of the neuropeptides in neuroimmune interaction in fish. The NECs, by their role as sensors of hypoxia changes in the external environments, in combination with their endocrine nature and secretion of immunomodulatory substances would influence various types of immune cells that contain piscidin, such as mast cells and eosinophils, both showing interaction with the nervous system. The discovery of piscidins in the gill and skin, their diversity and their role in the regulation of immune response will lead to better selection of these immunomodulatory molecules as drug targets to retain antimicrobial barrier function and for aquaculture therapy in the future.
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Tuong DD, Huong DTT, Phuong NT, Bayley M, Milsom WK. Ventilatory responses of the clown knifefish, Chitala ornata, to arterial hypercapnia remain after gill denervation. J Comp Physiol B 2019; 189:673-683. [PMID: 31552490 DOI: 10.1007/s00360-019-01236-6] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2019] [Revised: 08/22/2019] [Accepted: 09/12/2019] [Indexed: 01/20/2023]
Abstract
The aim of this study was to corroborate the presence of CO2/H+-sensitive arterial chemoreceptors involved in producing air-breathing responses to aquatic hypercarbia in the facultative air-breathing clown knifefish (Chitala ornata) and to explore their possible location. Progressively increasing levels of CO2 mixed with air were injected into the air-breathing organ (ABO) of one group of intact fish to elevate internal PCO2 and decrease blood pH. Another group of fish in which the gills were totally denervated was exposed to aquatic hypercarbia (pH ~ 6) or arterial hypercapnia in aquatic normocarbia (by injection of acetazolamide to increase arterial PCO2 and decrease blood pH). Air-breathing frequency, gill ventilation frequency, heart rate and arterial PCO2 and pH were recorded during all treatments. The CO2 injections into the ABO induced progressive increases in air-breathing frequency, but did not alter gill ventilation or heart rate. Exposure to both hypercarbia and acetazolamide post-denervation of the gills also produced significant air-breathing responses, but no changes in gill ventilation. While all treatments produced increases in arterial PCO2 and decreases in blood pH, the modest changes in arterial PCO2/pH in the acetazolamide treatment produced the greatest increases in air-breathing frequency. These results strengthen the evidence that internal CO2/H+ sensing is involved in the stimulation of air breathing in clown knifefish and suggest that it involves extra-branchial chemoreceptors possibly situated either centrally or in the air-breathing organ.
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Affiliation(s)
- Dang Diem Tuong
- College of Aquaculture and Fisheries, Can Tho University, Can Tho, Vietnam.
| | - Do Thi Thanh Huong
- College of Aquaculture and Fisheries, Can Tho University, Can Tho, Vietnam
| | | | - Mark Bayley
- Department of Bioscience Zoophysiology, Aarhus University, Aarhus, Denmark
| | - William K Milsom
- Department of Zoology, University of British Columbia, Vancouver, Canada
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6
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Kolesnikova EE. Neurophysiological Mechanisms of Respiratory Activity in Cyclostomes and Fish during Aquatic Breathing. J EVOL BIOCHEM PHYS+ 2019. [DOI: 10.1134/s0022093019020017] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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7
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Green S, Dietrich MR, Leonelli S, Ankeny RA. 'Extreme' organisms and the problem of generalization: interpreting the Krogh principle. HISTORY AND PHILOSOPHY OF THE LIFE SCIENCES 2018; 40:65. [PMID: 30382416 PMCID: PMC6208786 DOI: 10.1007/s40656-018-0231-0] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/10/2018] [Accepted: 10/17/2018] [Indexed: 05/22/2023]
Abstract
Many biologists appeal to the so-called Krogh principle when justifying their choice of experimental organisms. The principle states that "for a large number of problems there will be some animal of choice, or a few such animals, on which it can be most conveniently studied". Despite its popularity, the principle is often critiqued for implying unwarranted generalizations from optimal models. We argue that the Krogh principle should be interpreted in relation to the historical and scientific contexts in which it has been developed and used. We interpret the Krogh Principle as a heuristic, i.e., as a recommendation to approach biological problems through organisms where a specific trait or physiological mechanism is expected to be most distinctively displayed or most experimentally accessible. We designate these organisms "Krogh organisms". We clarify the differences between uses of model organisms and non-standard Krogh organisms. Among these is the use of Krogh organisms as "negative models" in biomedical research, where organisms are chosen for their dissimilarity to human physiology. Importantly, the representational scope of Krogh organisms and the generalizability of their characteristics are not fixed or assumed but explored through experimental studies. Research on Krogh organisms is steeped in the comparative method characteristic of zoology and comparative physiology, in which studies of biological variation produce insights into general physiological constraints. Accordingly, we conclude that the Krogh principle exemplifies the advantages of studying biological variation as a strategy to produce generalizable insights.
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Affiliation(s)
- Sara Green
- Department of Science Education, University of Copenhagen, Copenhagen, Denmark
| | - Michael R. Dietrich
- Department of History and Philosophy of Science, University of Pittsburgh, Pittsburgh, USA
| | - Sabina Leonelli
- Department of Sociology, Philosophy and Anthropology, University of Exeter, Exeter, UK
| | - Rachel A. Ankeny
- School of Humanities, University of Adelaide, Adelaide, Australia
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8
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Green S, Dietrich MR, Leonelli S, Ankeny RA. 'Extreme' organisms and the problem of generalization: interpreting the Krogh principle. HISTORY AND PHILOSOPHY OF THE LIFE SCIENCES 2018. [PMID: 30382416 DOI: 10.1007/s40656-017-0165-y] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
Many biologists appeal to the so-called Krogh principle when justifying their choice of experimental organisms. The principle states that "for a large number of problems there will be some animal of choice, or a few such animals, on which it can be most conveniently studied". Despite its popularity, the principle is often critiqued for implying unwarranted generalizations from optimal models. We argue that the Krogh principle should be interpreted in relation to the historical and scientific contexts in which it has been developed and used. We interpret the Krogh Principle as a heuristic, i.e., as a recommendation to approach biological problems through organisms where a specific trait or physiological mechanism is expected to be most distinctively displayed or most experimentally accessible. We designate these organisms "Krogh organisms". We clarify the differences between uses of model organisms and non-standard Krogh organisms. Among these is the use of Krogh organisms as "negative models" in biomedical research, where organisms are chosen for their dissimilarity to human physiology. Importantly, the representational scope of Krogh organisms and the generalizability of their characteristics are not fixed or assumed but explored through experimental studies. Research on Krogh organisms is steeped in the comparative method characteristic of zoology and comparative physiology, in which studies of biological variation produce insights into general physiological constraints. Accordingly, we conclude that the Krogh principle exemplifies the advantages of studying biological variation as a strategy to produce generalizable insights.
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Affiliation(s)
- Sara Green
- Department of Science Education, University of Copenhagen, Copenhagen, Denmark.
| | - Michael R Dietrich
- Department of History and Philosophy of Science, University of Pittsburgh, Pittsburgh, USA
| | - Sabina Leonelli
- Department of Sociology, Philosophy and Anthropology, University of Exeter, Exeter, UK
| | - Rachel A Ankeny
- School of Humanities, University of Adelaide, Adelaide, Australia
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9
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The sensing of respiratory gases in fish: Mechanisms and signalling pathways. Respir Physiol Neurobiol 2016; 224:71-9. [DOI: 10.1016/j.resp.2015.06.007] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2015] [Revised: 06/16/2015] [Accepted: 06/17/2015] [Indexed: 12/29/2022]
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10
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Jonz MG, Zachar PC, Da Fonte DF, Mierzwa AS. Peripheral chemoreceptors in fish: A brief history and a look ahead. Comp Biochem Physiol A Mol Integr Physiol 2015; 186:27-38. [DOI: 10.1016/j.cbpa.2014.09.002] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2014] [Revised: 09/03/2014] [Accepted: 09/03/2014] [Indexed: 11/24/2022]
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11
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Bessemer RA, Butler KMA, Tunnah L, Callaghan NI, Rundle A, Currie S, Dieni CA, MacCormack TJ. Cardiorespiratory toxicity of environmentally relevant zinc oxide nanoparticles in the freshwater fishCatostomus commersonii. Nanotoxicology 2014; 9:861-70. [DOI: 10.3109/17435390.2014.982737] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
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12
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Sengar M, Yadav L, Gopesh A, Zaccone D, Lauriano ER, Capillo G. Fine structure of diffused pseudobranchial neurosecretory cells associated with carotid labyrinth in an air-breathing catfishClarias batrachus. ACTA ZOOL-STOCKHOLM 2014. [DOI: 10.1111/azo.12100] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Affiliation(s)
- Manvendra Sengar
- Department of Zoology; Institute of Basic Science; Bundelkhand University; Jhansi 284128 UP India
| | - Laxmi Yadav
- Department of Zoology; Smt. Indira Gandhi Govt. P.G. College; Lalganj Mirzapur 211003 UP India
| | - Anita Gopesh
- Department of Zoology; University of Allahabad; Allahabad 211002 UP India
| | - Daniele Zaccone
- Dipartimento di Scienze Dell'Ambiente, della Sicurezza, del Territorio, degli Alimenti e della Salute (S.A.S.T.S.); Viale Stagno d'Alcontres 31; University of Messina; I-98166 Messina Italy
| | - Eugenia Rita Lauriano
- Dipartimento di Scienze Dell'Ambiente, della Sicurezza, del Territorio, degli Alimenti e della Salute (S.A.S.T.S.); Viale Stagno d'Alcontres 31; University of Messina; I-98166 Messina Italy
| | - Gioiele Capillo
- Dipartimento di Scienze Dell'Ambiente, della Sicurezza, del Territorio, degli Alimenti e della Salute (S.A.S.T.S.); Viale Stagno d'Alcontres 31; University of Messina; I-98166 Messina Italy
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13
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Abstract
Organisms exposed to altered salinity must be able to perceive osmolality change because metabolism has evolved to function optimally at specific intracellular ionic strength and composition. Such osmosensing comprises a complex physiological process involving many elements at organismal and cellular levels of organization. Input from numerous osmosensors is integrated to encode magnitude, direction, and ionic basis of osmolality change. This combinatorial nature of osmosensing is discussed with emphasis on fishes.
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Affiliation(s)
- Dietmar Kültz
- Department of Animal Science, Physiological Genomics Group, University of California, Davis, Davis, California
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14
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Zachar PC, Jonz MG. Confocal imaging of Merkel-like basal cells in the taste buds of zebrafish. Acta Histochem 2012; 114:101-15. [PMID: 21477848 DOI: 10.1016/j.acthis.2011.03.006] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2011] [Revised: 03/07/2011] [Accepted: 03/09/2011] [Indexed: 10/18/2022]
Abstract
The oropharyngeal cavity in fish supports a range of sensory modalities, including detection of chemical and mechanical stimuli. Taste buds are found throughout this tissue and may participate in both processes. We used confocal microscopy and immunohistochemistry to characterize the morphology of Merkel-like cells and their association with other cell types and nerve fibers of the taste bud in the vertebrate model, the zebrafish. In addition, we document procedures for the observation of these structures in whole-tissue preparations from larvae and adults using zebrafish-specific and monoclonal antibodies. A single microvillus Merkel-like cell was found in each taste bud regardless of age or location. Merkel-like cells were neurosecretory, as indicated by labelling with the styryl dye, FM1-43, and the synaptic vesicle marker, SV2. Merkel-like cells were associated with SV2- and calretinin-positive taste receptor cells, received innervation from discoid aggregations of nerve fibers, and retained serotonin-filled synaptic vesicles oriented within the cytoplasm toward adjacent innervation. Moreover, a ring-like formation of nerve endings was identified with the neuronal marker, zn-12 that circumscribed the taste receptor area, surrounding calretinin-immunoreactive taste cell microvilli, and appeared to associate with the nerve plexus adjacent to Merkel-like cells. We suggest that these nerve fibers are somatosensory, perhaps associated with mechanoreception or the common chemical sense.
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16
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Secourgeon JF. [Hypoxaemia, peripheral chemoreceptors and fetal heart rate]. ACTA ACUST UNITED AC 2011; 41:26-40. [PMID: 21798673 DOI: 10.1016/j.jgyn.2011.06.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2010] [Revised: 06/04/2011] [Accepted: 06/14/2011] [Indexed: 10/17/2022]
Abstract
The perinatal results of the widespread adoption of the continuous electronic fetal heart rate monitoring during labor remain rather disappointing. This is due in part to a lack of consistent interpretation of the fetal heart tracings. Despite efforts by referral agencies over the past decade the situation has not improved. In defense of practitioners the heterogeneity and complexity of definitions and classifications patterns especially morphological currently proposed should be noted. Whereas with the recent advances in the field of neuroscience, it is now possible to visualize the chain of pathophysiological events that lead from the hypoxemic stimulus of the glomus cell to changes in the morphology of the fetal heart rate tracing. Thus by taking some examples of real situations, we propose a method of analysis that dissects the fetal heart tracing and take into account the functional specifications of the chemoreceptor when exposed to a hypoxic environment. Furthermore we can identify tracings with a "threshold effect" and also "sensitization and desensitization effects" according to the intensity, duration and recurrence of hypoxaemic episodes. This new approach based upon specific research into the mechanism behind the fetal heart rate abnormalities may be useful to complement the morphological study of the fetal heart tracing, to provide a better idea of the fetal status and to better define the indications of fetal blood sampling procedures.
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Affiliation(s)
- J-F Secourgeon
- Service d'obstétrique, pôle femme-mère-enfant, centre hospitalier de Côte Basque, 13, avenue de l'Interne-Jacques-Loëb, 64100 Bayonne, France.
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17
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McMullan S, Pilowsky PM. The effects of baroreceptor stimulation on central respiratory drive: A review. Respir Physiol Neurobiol 2010; 174:37-42. [DOI: 10.1016/j.resp.2010.07.009] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2010] [Revised: 06/30/2010] [Accepted: 07/22/2010] [Indexed: 02/07/2023]
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18
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Pan TCF, Burggren WW. Onset and early development of hypoxic ventilatory responses and branchial neuroepithelial cells in Xenopus laevis. Comp Biochem Physiol A Mol Integr Physiol 2010; 157:382-91. [PMID: 20728560 DOI: 10.1016/j.cbpa.2010.08.018] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2010] [Revised: 08/09/2010] [Accepted: 08/10/2010] [Indexed: 11/17/2022]
Abstract
Onset and ontogeny of the O₂ chemoreceptive control of ventilation was investigated in Xenopus laevis. The density and size of branchial serotonin-immunoreactive neuroepithelial cells (5-HT-IR NECs) were also determined using confocal immunofluorescent microscopy. Larvae started gill ventilation at 3 days post-fertilization (dpf), and, at this early stage, acute hypoxic exposure produced an increase in frequency from 28 ± 4 to 60 ± 2 beats x min⁻¹. Concurrent with the onset of ventilatory responses, 5-HT-IR NECs appeared in the gill filament bud. Lung ventilation began at 5 dpf and exhibited a 3-fold increase in frequency during acute hypoxia. At 10 dpf, gill ventilatory sensitivity to hypoxia increased, as did NEC density, from 15 ± 1 (5 dpf) to 29 ± 2 (10 dpf) cells x mm of filament⁻¹. Unlike ventilation frequency, gill ventilation amplitude and lung expired volume were unaltered by acute hypoxia. Chronic exposure to moderate hypoxia, at a P(O₂) of 110 mmHg, attenuated acute responses to moderate hypoxia at 10 and 14 dpf but had no effect at more severe hypoxia or at other stages. Chronic hypoxia also stimulated 5-HT-IR NECs growth at 21 dpf. Collectively, larvae at 5 dpf exhibited strong O₂-driven gill and lung ventilatory responses, and between 10 and 21 dpf, the early hypoxic responses can be shaped by the ambient P(O₂).
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Affiliation(s)
- Tien-Chien F Pan
- Developmental Physiology and Genetics Research Cluster, Department of Biological Sciences, University of North Texas, Denton, Texas 76203-5017, USA.
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19
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Gopesh A, Sengar M, Tiwari S. Presence of paraneuronal pseudobranchial neurosecretory system in the gill region of two air-breathing clupeids, Notopterus chitala and Notopterus notopterus. Respir Physiol Neurobiol 2010; 171:135-43. [PMID: 20206306 DOI: 10.1016/j.resp.2010.02.012] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2009] [Revised: 02/18/2010] [Accepted: 02/24/2010] [Indexed: 11/15/2022]
Abstract
The pseudobranchial neurosecretory system (PNS) is a system of neurosecretion observed in certain groups of teleosts, which are air-breathing or known to tolerate low oxygen tension in the surrounding water. Like other neuroendocrine cells of gill, cells belonging to this system have also been observed to have a role in condition of hypoxia. Uniformly found in all catfish species, the system was reported to be present in few non-catfish groups also, viz.-Atheriniformes, Channiformes (Devi, 1987), Perciformes, and Clupeiformes (Srivastava et al., 1981; Gopesh, 1983). In an attempt to study the structure and organization of the pseudobranchial neurosecretory system in non-catfish species of teleost, present investigation was undertaken in two species of Notopterus, viz. Notopterus chitala and Notopterus notopterus. The histological observations, using neurosecretion specific stains, undertaken on two clupeids are reported and the findings are discussed in the light of association of PNS with Carotid gland-a structure of intermediate stage in the process of transformation of pseudobranch into the carotid labyrinth, in course of evolution and also the air-breathing habit of the fish.
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Affiliation(s)
- A Gopesh
- Department of Zoology, University of Allahabad, Allahabad 211002, U.P., India.
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Abstract
The fish gill is a highly complex organ that performs a wide variety of physiological processes and receives extensive nervous innervation from both afferent (sensory) and efferent (motor) fibres. Innervation from the latter source includes autonomic nerve fibres of spinal (sympathetic) and cranial (parasympathetic) origin whose primary role is to induce vasomotor changes within the respiratory or nonrespiratory pathways of the gill vasculature. Autonomic control of the gill occurs by nerve fibres identified as adrenergic, cholinergic, and more recent evidence indicates that nonadrenergic-noncholinergic (NANC) nerve fibres, such as those that express amines, peptides, or nitric oxide, may also play an important role. The distribution and physiological function of NANC nerve fibres, however, is less clear. This review primarily discusses histochemical studies that have characterized the nervous innervation and autonomic control of the gill vasculature. In addition, supporting evidence from recent studies for the efferent control, or modulation, of other homeostatic processes in the gill is examined.
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