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Zimmer AM. Ammonia excretion by the fish gill: discoveries and ideas that shaped our current understanding. J Comp Physiol B 2024:10.1007/s00360-024-01561-5. [PMID: 38849577 DOI: 10.1007/s00360-024-01561-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2023] [Revised: 03/06/2024] [Accepted: 05/15/2024] [Indexed: 06/09/2024]
Abstract
The fish gill serves many physiological functions, among which is the excretion of ammonia, the primary nitrogenous waste in most fishes. Although it is the end-product of nitrogen metabolism, ammonia serves many physiological functions including acting as an acid equivalent and as a counter-ion in mechanisms of ion regulation. Our current understanding of the mechanisms of ammonia excretion have been influenced by classic experimental work, clever mechanistic approaches, and modern molecular and genetic techniques. In this review, I will overview the history of the study of ammonia excretion by the gills of fishes, highlighting the important advancements that have shaped this field with a nearly 100-year history. The developmental and evolutionary implications of an ammonia and gill-dominated nitrogen regulation strategy in most fishes will also be discussed. Throughout the review, I point to areas in which more work is needed to push forward this field of research that continues to produce novel insights and discoveries that will undoubtedly shape our overall understanding of fish physiology.
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Affiliation(s)
- Alex M Zimmer
- Department of Biological Sciences, University of New Brunswick, 100 Tucker Park Road, Saint John, Saint John, New Brunswick, E2L 4L5, Canada.
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2
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Zhao XF, Huang J, Li W, Wang SY, Liang LQ, Zhang LM, Liew HJ, Chang YM. Rh proteins and H + transporters involved in ammonia excretion in Amur Ide (Leuciscus waleckii) under high alkali exposure. ECOTOXICOLOGY AND ENVIRONMENTAL SAFETY 2024; 273:116160. [PMID: 38432157 DOI: 10.1016/j.ecoenv.2024.116160] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/03/2023] [Revised: 02/22/2024] [Accepted: 02/25/2024] [Indexed: 03/05/2024]
Abstract
High alkaline environment can lead to respiratory alkalosis and ammonia toxification to freshwater fish. However, the Amur ide (Leuciscus waleckii), which inhabits an extremely alkaline lake in China with titratable alkalinity up to 53.57 mM (pH 9.6) has developed special physiological and molecular mechanisms to adapt to such an environment. Nevertheless, how the Amur ide can maintain acid-base balance and perform ammonia detoxification effectively remains unclear. Therefore, this study was designed to study the ammonia excretion rate (Tamm), total nitrogen accumulation in blood and tissues, including identification, expression, and localization of ammonia-related transporters in gills of both the alkali and freshwater forms of the Amur ide. The results showed that the freshwater form Amur ide does not have a perfect ammonia excretion mechanism exposed to high-alkaline condition. Nevertheless, the alkali form of Amur ide was able to excrete ammonia better than freshwater from Amur ide, which was facilitated by the ionocytes transporters (Rhbg, Rhcg1, Na+/H+ exchanger 2 (NHE2), and V-type H+ ATPase (VHA)) in the gills. Converting ammonia into urea served as an ammonia detoxication strategy to reduced endogenous ammonia accumulation under high-alkaline environment.
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Affiliation(s)
- Xue Fei Zhao
- National and Local Joint Engineering Laboratory for Freshwater Fish Breeding, Heilongjiang River Fisheries Research Institute, Chinese Academy of Fishery Sciences, Harbin 150070, China; College of Wildlife and Protected Area, Northeast Forestry University, Harbin 150040, China
| | - Jing Huang
- National and Local Joint Engineering Laboratory for Freshwater Fish Breeding, Heilongjiang River Fisheries Research Institute, Chinese Academy of Fishery Sciences, Harbin 150070, China
| | - Wen Li
- National and Local Joint Engineering Laboratory for Freshwater Fish Breeding, Heilongjiang River Fisheries Research Institute, Chinese Academy of Fishery Sciences, Harbin 150070, China; College of Fisheries and Life Science, Shanghai Ocean University, Shanghai 2000, China
| | - Shuang Yi Wang
- National and Local Joint Engineering Laboratory for Freshwater Fish Breeding, Heilongjiang River Fisheries Research Institute, Chinese Academy of Fishery Sciences, Harbin 150070, China; BGI Genomics, BGI-Shenzhen, Shenzhen, Guangdong 518083, China
| | - Li Qun Liang
- National and Local Joint Engineering Laboratory for Freshwater Fish Breeding, Heilongjiang River Fisheries Research Institute, Chinese Academy of Fishery Sciences, Harbin 150070, China
| | - Li Min Zhang
- National and Local Joint Engineering Laboratory for Freshwater Fish Breeding, Heilongjiang River Fisheries Research Institute, Chinese Academy of Fishery Sciences, Harbin 150070, China
| | - Hon Jung Liew
- Higher Institution Center of Excellence (HICoE), Institute of Tropical Aquaculture and Fisheries, Universiti of Malaysia Terengganu, Kuala Nerus, Terengganu 21030, Malaysia
| | - Yu Mei Chang
- National and Local Joint Engineering Laboratory for Freshwater Fish Breeding, Heilongjiang River Fisheries Research Institute, Chinese Academy of Fishery Sciences, Harbin 150070, China.
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Quijada-Rodriguez AR, Fehsenfeld S, Marini AM, Wilson JM, Nash MT, Sachs M, Towle DW, Weihrauch D. Branchial CO 2 and ammonia excretion in crustaceans: Involvement of an apical Rhesus-like glycoprotein. Acta Physiol (Oxf) 2024; 240:e14078. [PMID: 38205922 DOI: 10.1111/apha.14078] [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: 02/07/2023] [Revised: 10/13/2023] [Accepted: 12/14/2023] [Indexed: 01/12/2024]
Abstract
AIM To determine whether the crustacean Rh1 protein functions as a dual CO2 /ammonia transporter and investigate its role in branchial ammonia excretion and acid-base regulation. METHODS Sequence analysis of decapod Rh1 proteins was used to determine the conservation of amino acid residues putatively involved in ammonia transport and CO2 binding in human and bacterial Rh proteins. Using the Carcinus maenas Rh1 protein (CmRh1) as a representative of decapod Rh1 proteins, we test the ammonia and CO2 transport capabilities of CmRh1 through heterologous expression in yeast and Xenopus oocytes coupled with site-directed mutagenesis. Quantitative PCR was used to assess the distribution of CmRh1 mRNA in various tissues. Western blotting was used to assess CmRh1 protein expression changes in response to high environmental ammonia and CO2 . Further, immunohistochemistry was used to assess sub-cellular localization of CmRh1 and a membrane-bound carbonic anhydrase (CmCAg). RESULTS Sequence analysis of decapod Rh proteins revealed high conservation of several amino acid residues putatively involved in conducting ammonia transport and CO2 binding. Expression of CmRh1 in Xenopus oocytes enhanced both ammonia and CO2 transport which was nullified in CmRh1 D180N mutant oocytes. Transport of the ammonia analog methylamine by CmRh1 is dependent on both ionized and un-ionized ammonia/methylamine species. CmRh1 was co-localized with CmCAg to the apical membrane of the crustacean gill and only experienced decreased protein expression in the anterior gills when exposed to high environmental ammonia. CONCLUSION CmRh1 is the first identified apical transporter-mediated route for ammonia and CO2 excretion in the crustacean gill. Our findings shed further light on the potential universality of dual ammonia and CO2 transport capacity of Rhesus glycoproteins in both vertebrates and invertebrates.
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Affiliation(s)
- Alex R Quijada-Rodriguez
- Department of Biological Sciences, University of Manitoba, Winnipeg, Manitoba, Canada
- Department of Biology, Wilfrid Laurier University, Waterloo, Ontario, Canada
| | - Sandra Fehsenfeld
- Department of Biological Sciences, University of Manitoba, Winnipeg, Manitoba, Canada
- Département de biologie, chimie et géographie, Université du Québec à Rimouski, Rimouski, Quebec, Canada
| | - Anna-Maria Marini
- Biology of Membrane Transport Laboratory, Molecular Biology Department, Université Libre de Bruxelles, Bruxelles, Belgium
- WELBIO, Wavre, Belgium
| | - Jonathan M Wilson
- Department of Biology, Wilfrid Laurier University, Waterloo, Ontario, Canada
| | - Mikyla T Nash
- Department of Biological Sciences, University of Manitoba, Winnipeg, Manitoba, Canada
| | - Maria Sachs
- Department of Biological Sciences, University of Manitoba, Winnipeg, Manitoba, Canada
| | - David W Towle
- Mount Desert Island Biological Laboratory, Salisbury Cove, Maine, USA
| | - Dirk Weihrauch
- Department of Biological Sciences, University of Manitoba, Winnipeg, Manitoba, Canada
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Zahrae Radi F, Bencheikh N, Anarghou H, Bouhrim M, Alqahtani AS, Hawwal MF, Noman OM, Bnouham M, Zair T. Quality control, phytochemical profile, and biological activities of Crataegus monogyna Jacq. and Crataegus laciniata Ucria fruits aqueous extracts. Saudi Pharm J 2023; 31:101753. [PMID: 37705878 PMCID: PMC10495647 DOI: 10.1016/j.jsps.2023.101753] [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: 03/25/2023] [Accepted: 08/17/2023] [Indexed: 09/15/2023] Open
Abstract
The current study aimed to evaluate the phytochemical composition, quality control, and antioxidant, antibacterial, antifungal, antihyperglycemic activities, and toxicity assessment of Crataegus monogyna Jacq (C. monogyna) and Crataegus laciniata Ucria (C. laciniata) fruits aqueous extracts. The quality control of the plant material revealed that it is free of heavy metals and the acidity and ash parameters comply with international standards. HPLC-DAD analysis revealed the presence of eight phenolic compounds in the C. monogyna extract and nine compounds in the C. laciniata extract, with coumaric acid present only in the C. laciniata extract. According to the findings, both extracts are high in total polyphenols, total flavonoids, and condensed tannins. The results of the antioxidant activity revealed that our extracts have significant effects against 2, 2-diphényl 1-picrylhydrazyle (DPPH), and Ferric Reducing Antioxidant Power (FRAP). The antibacterial test revealed that the two extracts tested were effective against four bacterial strains, including Staphylococcus aureus, Escherichia coli, Enterobacter cloacae, and Shigella dysenteria, but were ineffective against Salmonella typhi, and Acinetobacter baumanii. In addition, extracts from both plants showed remarkable antihyperglycemic activity with no acute toxicity. In conclusion, the extracts studied could be a good source of bioactive molecules with antioxidant, antimicrobial, and anti-diabetic activity for pharmaceutical applications.
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Affiliation(s)
- Fatima Zahrae Radi
- Research Team of Chemistry of Bioactive Molecules and the Environment, Laboratory of Innovative Materials and Biotechnology of Natural Resources, Faculty of Sciences, Moulay Ismail University of Meknes, B.P. 11201 Zitoune, Meknes 50070, Morocco
| | - Noureddine Bencheikh
- Laboratory of Bioressources, Biotechnology, Ethnopharmacology and Health, Department of Biology, Faculty of Sciences, University Mohammed First, Boulevard Mohamed VI BP 717, Oujda 60000, Morocco
| | - Hammou Anarghou
- Laboratory of Biological Engineering, Team of Functional and Pathological Biology, University Sultan Moulay Slimane, Faculty of Sciences and Technology, Beni Mellal, Morocco
| | - Mohamed Bouhrim
- Laboratory of Biological Engineering, Team of Functional and Pathological Biology, University Sultan Moulay Slimane, Faculty of Sciences and Technology, Beni Mellal, Morocco
- Laboratories TBC, Laboratory of Pharmacology, Pharmacokinetics and Clinical Pharmacy, Faculty of Pharmacy, University of Lille, Lille, France
| | - Ali S. Alqahtani
- Department of Pharmacognosy, College of Pharmacy, King Saud University, PO Box 2457, Riyadh 11451, Saudi Arabia
| | - Mohammed F. Hawwal
- Department of Pharmacognosy, College of Pharmacy, King Saud University, PO Box 2457, Riyadh 11451, Saudi Arabia
| | - Omar M. Noman
- Department of Pharmacognosy, College of Pharmacy, King Saud University, PO Box 2457, Riyadh 11451, Saudi Arabia
| | - Mohamed Bnouham
- Laboratory of Bioressources, Biotechnology, Ethnopharmacology and Health, Department of Biology, Faculty of Sciences, University Mohammed First, Boulevard Mohamed VI BP 717, Oujda 60000, Morocco
| | - Touriya Zair
- Research Team of Chemistry of Bioactive Molecules and the Environment, Laboratory of Innovative Materials and Biotechnology of Natural Resources, Faculty of Sciences, Moulay Ismail University of Meknes, B.P. 11201 Zitoune, Meknes 50070, Morocco
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Cazorla-Vázquez S, Kösters P, Bertz S, Pfister F, Daniel C, Dedden M, Zundler S, Jobst-Schwan T, Amann K, Engel FB. Adhesion GPCR Gpr126 (Adgrg6) Expression Profiling in Zebrafish, Mouse, and Human Kidney. Cells 2023; 12:1988. [PMID: 37566066 PMCID: PMC10417176 DOI: 10.3390/cells12151988] [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: 06/27/2023] [Revised: 07/22/2023] [Accepted: 07/29/2023] [Indexed: 08/12/2023] Open
Abstract
Adhesion G protein-coupled receptors (aGPCRs) comprise the second-largest class of GPCRs, the most common target for approved pharmacological therapies. aGPCRs play an important role in development and disease and have recently been associated with the kidney. Several aGPCRs are expressed in the kidney and some aGPCRs are either required for kidney development or their expression level is altered in diseased kidneys. Yet, general aGPCR function and their physiological role in the kidney are poorly understood. Here, we characterize in detail Gpr126 (Adgrg6) expression based on RNAscope® technology in zebrafish, mice, and humans during kidney development in adults. Gpr126 expression is enriched in the epithelial linage during nephrogenesis and persists in the adult kidney in parietal epithelial cells, collecting ducts, and urothelium. Single-cell RNAseq analysis shows that gpr126 expression is detected in zebrafish in a distinct ionocyte sub-population. It is co-detected selectively with slc9a3.2, slc4a4a, and trpv6, known to be involved in apical acid secretion, buffering blood or intracellular pH, and to maintain high cytoplasmic Ca2+ concentration, respectively. Furthermore, gpr126-expressing cells were enriched in the expression of potassium transporter kcnj1a.1 and gcm2, which regulate the expression of a calcium sensor receptor. Notably, the expression patterns of Trpv6, Kcnj1a.1, and Gpr126 in mouse kidneys are highly similar. Collectively, our approach permits a detailed insight into the spatio-temporal expression of Gpr126 and provides a basis to elucidate a possible role of Gpr126 in kidney physiology.
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Affiliation(s)
- Salvador Cazorla-Vázquez
- Experimental Renal and Cardiovascular Research, Department of Nephropathology, Institute of Pathology, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), 91054 Erlangen, Germany; (S.C.-V.); (P.K.)
| | - Peter Kösters
- Experimental Renal and Cardiovascular Research, Department of Nephropathology, Institute of Pathology, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), 91054 Erlangen, Germany; (S.C.-V.); (P.K.)
| | - Simone Bertz
- Institute of Pathology, University Hospital Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), 91054 Erlangen, Germany;
| | - Frederick Pfister
- Department of Nephropathology, Institute of Pathology, University Hospital Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), 91054 Erlangen, Germany; (F.P.); (C.D.); (K.A.)
| | - Christoph Daniel
- Department of Nephropathology, Institute of Pathology, University Hospital Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), 91054 Erlangen, Germany; (F.P.); (C.D.); (K.A.)
| | - Mark Dedden
- Department of Medicine 1, University Hospital Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), 91054 Erlangen, Germany; (M.D.); (S.Z.)
| | - Sebastian Zundler
- Department of Medicine 1, University Hospital Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), 91054 Erlangen, Germany; (M.D.); (S.Z.)
| | - Tilman Jobst-Schwan
- Department of Nephrology and Hypertension, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), 91054 Erlangen, Germany;
- Research Center On Rare Kidney Diseases (RECORD), University Hospital Erlangen, Friedrich-Alexander-University Erlangen-Nürnberg (FAU), 91054 Erlangen, Germany
| | - Kerstin Amann
- Department of Nephropathology, Institute of Pathology, University Hospital Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), 91054 Erlangen, Germany; (F.P.); (C.D.); (K.A.)
| | - Felix B. Engel
- Experimental Renal and Cardiovascular Research, Department of Nephropathology, Institute of Pathology, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), 91054 Erlangen, Germany; (S.C.-V.); (P.K.)
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Hung GY, Pan YC, Horng JL, Lin LY. Sublethal effects of methylmercury on lateral line sensory and ion-regulatory functions in zebrafish embryos. Comp Biochem Physiol C Toxicol Pharmacol 2023; 271:109700. [PMID: 37442313 DOI: 10.1016/j.cbpc.2023.109700] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/22/2023] [Revised: 06/26/2023] [Accepted: 07/09/2023] [Indexed: 07/15/2023]
Abstract
Methylmercury can interfere with the normal functioning of the nervous system, causing a variety of behavioral and physiological changes in fish. However, the influence of MeHg on the lateral line sensory and ion-regulatory functions of fish is not clear. Zebrafish embryos were utilized as a model to address this question. After exposure to water-borne MeHg (5, 10, 50, or 100 ppb) for 96 h (4-100 h post-fertilization), the survival rate declined by ca. 50 % at 100 ppb. However, MeHg at sublethal concentrations delayed hatching and decreased heart rates and body length. As to effects on the lateral line sensory system, MeHg at ≥10 ppb decreased the number of hair cells and impaired hair bundles and Ca2+-mediated mechanical transduction. As to ion regulation, MeHg at ≥10 ppb decreased the densities of skin stem cells and ionocytes, leading to declines in ion (Na+, K+, and Ca2+) contents and H+/NH4+ excretion levels. A gene expression analysis also revealed declines in messenger RNA levels of several ion-regulatory genes (ncc2b, trpv6v1a, trpv5/6, ncx1b, and rhcg1). This study demonstrated that the lateral line sensory and ion regulatory functions of fish are extremely sensitive to MeHg.
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Affiliation(s)
- Giun-Yi Hung
- Division of Pediatric Hematology and Oncology, Department of Pediatrics, Taipei Veterans General Hospital, Taipei 112, Taiwan; School of Medicine, College of Medicine, National Yang Ming Chiao Tung University, Taipei 112, Taiwan
| | - Yu-Chin Pan
- Department of Life Science, National Taiwan Normal University, Taipei 11677, Taiwan
| | - Jiun-Lin Horng
- Department of Anatomy and Cell Biology, School of Medicine, College of Medicine, Taipei Medical University, Taipei 11042, Taiwan
| | - Li-Yih Lin
- Department of Life Science, National Taiwan Normal University, Taipei 11677, Taiwan.
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7
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Kantha P, Liu ST, Horng JL, Lin LY. Acute exposure to polystyrene nanoplastics impairs skin cells and ion regulation in zebrafish embryos. AQUATIC TOXICOLOGY (AMSTERDAM, NETHERLANDS) 2022; 248:106203. [PMID: 35617773 DOI: 10.1016/j.aquatox.2022.106203] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/24/2021] [Revised: 04/27/2022] [Accepted: 05/18/2022] [Indexed: 06/15/2023]
Abstract
The presence of nanoplastics in aquatic environments is a global problem. Accumulating evidence shows that nanoplastics can accumulate in fish and influence internal organs. However, it is still unknown if nanoplastics can impair skin cells (keratinocytes and ionocytes), which play critical roles in maintaining body fluid homeostasis. In the present study, zebrafish embryos were exposed to polystyrene nanoplastics (PS-NPs; 25 nm in size, at 0, 10, 25, and 50 mg/L) for 96 h to test the effects of PS-NPs on skin functions. After exposure to 50 mg/L, the survival rate, ion (Na+, K+, and Ca2+) contents, and acid/ammonia excretion by skin cells of embryos significantly declined. The apical structure of skin keratinocytes was damaged at 10, 25, and 50 mg/L. The number and mitochondrial activity of ionocytes were reduced at 25 and 50 mg/L. Reactive oxygen species (ROS) levels indicated by CellROX staining showed that both ionocytes and keratinocytes were under oxidative stress. PS-NPs reduced the mRNA expression of antioxidant genes (sod1, sod2, cat, and gpx1a), and promoted apoptosis-related genes (casp3a). Taken together, this study suggests that PS-NPs might suppress antioxidative reactions and induce oxidative stress, leading to mitochondrial damage and cell death of ionocytes, eventually impairing skin functions including ion uptake, pH regulation, and ammonia excretion.
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Affiliation(s)
- Phunsin Kantha
- Department of Life Science, School of Life Science, National Taiwan Normal University, Taipei, Taiwan; Biodiversity Program, Taiwan International Graduate Program, Biodiversity Research Center, Academia Sinica and National Taiwan Normal University, Taipei, Taiwan
| | - Sian-Tai Liu
- Department of Life Science, School of Life Science, National Taiwan Normal University, Taipei, Taiwan
| | - Jiun-Lin Horng
- Department of Anatomy and Cell Biology, School of Medicine, College of Medicine, Taipei Medical University, Taipei 11031, Taiwan
| | - Li-Yih Lin
- Department of Life Science, School of Life Science, National Taiwan Normal University, Taipei, Taiwan; Biodiversity Program, Taiwan International Graduate Program, Biodiversity Research Center, Academia Sinica and National Taiwan Normal University, Taipei, Taiwan.
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8
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Aranda-Morales SA, Peña-Marín ES, Jiménez-Martínez LD, Martínez-Burguete T, Martínez-Bautista G, Álvarez-Villagómez CS, De la Rosa-García S, Camarillo-Coop S, Martínez-García R, Guzmán-Villanueva LT, Álvarez-González CA. Expression of ion transport proteins and routine metabolism in juveniles of tropical gar (Atractosteus tropicus) exposed to ammonia. Comp Biochem Physiol C Toxicol Pharmacol 2021; 250:109166. [PMID: 34411697 DOI: 10.1016/j.cbpc.2021.109166] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/08/2021] [Revised: 07/13/2021] [Accepted: 08/06/2021] [Indexed: 12/14/2022]
Abstract
Tropical gar (Atractosteus tropicus) thrives in aquatic habitats with high levels of total nitrogen (TAN) and unionized ammonia (NH3). However, the tolerance of TAN and NH3, the excretion mechanisms involved, and the effects of these chemicals on routine metabolism are still unknown. Therefore, our objectives were to assess the acute toxicity of TAN and NH3 in A. tropicus juveniles after a 96-h exposure (LC50-96 h) to NH4Cl and after chronic exposure to two concentrations (15% and 30% of LC50-96 h TAN) for 12 days, as well as to evaluate the transcriptional effects associated with Rhesus proteins (rhag, rhbg, rhcg) and ion transporters (NHE, NKA, NKCC, and CFTR) in gills and skin; and to determine the effects of TAN and NH3 on routine metabolism through oxygen consumption (μM g-1 h-1) and gill ventilation frequency (beats min-1). LC50-96 h values were 100.20 ± 11.21 mg/L for TAN and 3.756 ± 0.259 mg/L for NH3. The genes encoding Rhesus proteins and ion transporters in gills and skin showed a differential expression according to TAN concentrations and exposure time. Oxygen consumption on day 12 showed significant differences between treatments with 15% and 30% TAN. Gill ventilation frequency on day 12 was higher in fish exposed to 30% TAN. In conclusion, A. tropicus juveniles are highly tolerant to TAN, showing upregulation of the genes involved in TAN excretion through gills and skin, which affects routine oxygen consumption and energetic cost. These findings are relevant for understanding adaptations in the physiological response of a tropical ancestral air-breathing fish.
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Affiliation(s)
- Sonia A Aranda-Morales
- División Académica de Ciencias Biológicas, Universidad Juárez Autónoma de Tabasco, Carretera Villahermosa-Cárdenas Km 0.5, C.P.86139 Villahermosa, Tabasco, Mexico
| | - Emyr S Peña-Marín
- División Académica de Ciencias Biológicas, Universidad Juárez Autónoma de Tabasco, Carretera Villahermosa-Cárdenas Km 0.5, C.P.86139 Villahermosa, Tabasco, Mexico; Consejo Nacional de Ciencia y Tecnología, Av. Insurgentes Sur 1582, Col. Crédito Constructor, Del. Benito Juárez C.P. 03940, Mexico
| | - Luis D Jiménez-Martínez
- División Académica Multidisciplinaria de Jalpa de Méndez, Universidad Juárez Autónoma de Tabasco, Carretera Nacajuca-Jalpa de Méndez R/a Rivera Alta, C.P. 86200 Jalpa de Méndez, Tabasco, Mexico
| | - Talhia Martínez-Burguete
- División Académica de Ciencias Biológicas, Universidad Juárez Autónoma de Tabasco, Carretera Villahermosa-Cárdenas Km 0.5, C.P.86139 Villahermosa, Tabasco, Mexico
| | - Gil Martínez-Bautista
- División Académica de Ciencias Biológicas, Universidad Juárez Autónoma de Tabasco, Carretera Villahermosa-Cárdenas Km 0.5, C.P.86139 Villahermosa, Tabasco, Mexico
| | - Carina S Álvarez-Villagómez
- División Académica de Ciencias Biológicas, Universidad Juárez Autónoma de Tabasco, Carretera Villahermosa-Cárdenas Km 0.5, C.P.86139 Villahermosa, Tabasco, Mexico
| | - Susana De la Rosa-García
- División Académica de Ciencias Biológicas, Universidad Juárez Autónoma de Tabasco, Carretera Villahermosa-Cárdenas Km 0.5, C.P.86139 Villahermosa, Tabasco, Mexico
| | - Susana Camarillo-Coop
- División Académica de Ciencias Biológicas, Universidad Juárez Autónoma de Tabasco, Carretera Villahermosa-Cárdenas Km 0.5, C.P.86139 Villahermosa, Tabasco, Mexico
| | - Rafael Martínez-García
- División Académica de Ciencias Biológicas, Universidad Juárez Autónoma de Tabasco, Carretera Villahermosa-Cárdenas Km 0.5, C.P.86139 Villahermosa, Tabasco, Mexico
| | - Laura T Guzmán-Villanueva
- Consejo Nacional de Ciencia y Tecnología, Av. Insurgentes Sur 1582, Col. Crédito Constructor, Del. Benito Juárez C.P. 03940, Mexico; Centro de Investigaciones Biológicas del Noroeste S.C., Av. Instituto Politécnico Nacional 195. Col. Playa Palo de Santa Rita Sur, 23096 La Paz, Baja California Sur, Mexico
| | - Carlos A Álvarez-González
- División Académica de Ciencias Biológicas, Universidad Juárez Autónoma de Tabasco, Carretera Villahermosa-Cárdenas Km 0.5, C.P.86139 Villahermosa, Tabasco, Mexico.
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Zimmer AM, Mandic M, Yew HM, Kunert E, Pan YK, Ha J, Kwong RWM, Gilmour KM, Perry SF. Use of a carbonic anhydrase Ca17a knockout to investigate mechanisms of ion uptake in zebrafish ( Danio rerio). Am J Physiol Regul Integr Comp Physiol 2021; 320:R55-R68. [PMID: 33085911 DOI: 10.1152/ajpregu.00215.2020] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
In fishes, branchial cytosolic carbonic anhydrase (CA) plays an important role in ion and acid-base regulation. The Ca17a isoform in zebrafish (Danio rerio) is expressed abundantly in Na+-absorbing/H+-secreting H+-ATPase-rich (HR) cells. The present study aimed to identify the role of Ca17a in ion and acid-base regulation across life stages using CRISPR/Cas9 gene editing. However, in preliminary experiments, we established that ca17a knockout is lethal with ca17a-/- mutants exhibiting a significant decrease in survival beginning at ∼12 days postfertilization (dpf) and with no individuals surviving past 19 dpf. Based on these findings, we hypothesized that ca17a-/- mutants would display alterations in ion and acid-base balance and that these physiological disturbances might underlie their early demise. Na+ uptake rates were significantly increased by up to 300% in homozygous mutants compared with wild-type individuals at 4 and 9 dpf; however, whole body Na+ content remained constant. While Cl- uptake was significantly reduced in ca17a-/- mutants, Cl- content was unaffected. Reduction of CA activity by Ca17a morpholino knockdown or ethoxzolamide treatments similarly reduced Cl- uptake, implicating Ca17a in the mechanism of Cl- uptake by larval zebrafish. H+ secretion, O2 consumption, CO2 excretion, and ammonia excretion were generally unaltered in ca17a-/- mutants. In conclusion, while the loss of Ca17a caused marked changes in ion uptake rates, providing strong evidence for a Ca17a-dependent Cl- uptake mechanism, the underlying causes of the lethality of this mutation in zebrafish remain unclear.
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Affiliation(s)
- Alex M Zimmer
- Department of Biology, University of Ottawa, Ottawa, Ontario, Canada
| | - Milica Mandic
- Department of Biology, University of Ottawa, Ottawa, Ontario, Canada
| | - Hong Meng Yew
- Department of Biology, University of Ottawa, Ottawa, Ontario, Canada
| | - Emma Kunert
- Department of Biology, University of Ottawa, Ottawa, Ontario, Canada
| | - Yihang K Pan
- Department of Biology, University of Ottawa, Ottawa, Ontario, Canada
| | - Jimmy Ha
- Department of Biology, University of Ottawa, Ottawa, Ontario, Canada
| | - Raymond W M Kwong
- Department of Biology, University of Ottawa, Ottawa, Ontario, Canada
| | | | - Steve F Perry
- Department of Biology, University of Ottawa, Ottawa, Ontario, Canada
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10
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Lee CY, Horng JL, Liu ST, Lin LY. Exposure to copper nanoparticles impairs ion uptake, and acid and ammonia excretion by ionocytes in zebrafish embryos. CHEMOSPHERE 2020; 261:128051. [PMID: 33113650 DOI: 10.1016/j.chemosphere.2020.128051] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/23/2020] [Revised: 08/15/2020] [Accepted: 08/17/2020] [Indexed: 06/11/2023]
Abstract
The potential toxicity of copper nanoparticles (CuNPs) to early stages of fishes is not fully understood, and little is known about their effects on ionocytes and associated functions. This study used zebrafish embryos as a model to investigate the toxic effects of CuNPs on two subtypes of ionocytes. Zebrafish embryos were exposed to 0.1, 1, and 3 mg L-1 CuNPs for 96 h. After exposure, whole-body Na+ and Ca2+ contents were significantly reduced at ≥0.1 mg L-1, while the K+ content had decreased at ≥1 mg L-1. H+ and NH4+ excretion by the skin significantly decreased at ≥1 mg L-1. The number of living ionocytes labeled with rhodamine-123 had significantly decreased with ≥0.1 mg L-1 CuNPs. The ionocyte subtypes of H+-ATPase-rich (HR) and Na+/K+-ATPase-rich (NaR) cells were labeled by immunostaining and had decreased with ≥1 mg L-1. Shrinkage of the apical opening of ionocytes was revealed by scanning electronic microscopy. Functional impairment was also reflected by changes in gene expressions, including ion transporters/channels and Ca2+-regulatory hormones. This study shows that CuNP exposure can impair two subtypes of ionocytes and their associated functions, including Na+/Ca2+ uptake and H+/NH4+ excretion in zebrafish embryos.
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Affiliation(s)
- Chih-Ying Lee
- Department of Life Science, School of Life Science, National Taiwan Normal University, Taipei, Taiwan; Division of Pediatric Hematology and Oncology, Department of Pediatrics, Taipei Veterans General Hospital, Taipei, Taiwan; Department of Pediatrics, Faculty of Medicine, School of Medicine, National Yang-Ming University, Taipei, Taiwan
| | - Jiun-Lin Horng
- Department of Anatomy and Cell Biology, School of Medicine, College of Medicine, Taipei Medical University, Taipei, Taiwan
| | - Sian-Tai Liu
- Department of Life Science, School of Life Science, National Taiwan Normal University, Taipei, Taiwan
| | - Li-Yih Lin
- Department of Life Science, School of Life Science, National Taiwan Normal University, Taipei, Taiwan.
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11
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Lin LY, Zheng JA, Huang SC, Hung GY, Horng JL. Ammonia exposure impairs lateral-line hair cells and mechanotransduction in zebrafish embryos. CHEMOSPHERE 2020; 257:127170. [PMID: 32497837 DOI: 10.1016/j.chemosphere.2020.127170] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/17/2020] [Revised: 05/18/2020] [Accepted: 05/20/2020] [Indexed: 06/11/2023]
Abstract
Ammonia (including NH3 and NH4+) is a major pollutant of freshwater environments. However, the toxic effects of ammonia on the early stages of fish are not fully understood, and little is known about the effects on the sensory system. In this study, we hypothesized that ammonia exposure can cause adverse effects on embryonic development and impair the lateral line system of fish. Zebrafish embryos were exposed to high-ammonia water (10, 15, 20, 25, and 30 mM NH4Cl; pH 7.0) for 96 h (0-96 h post-fertilization). The body length, heart rate, and otic vesicle size had significantly decreased with ≥15 mM NH4Cl, while the number and function of lateral-line hair cells had decreased with ≥10 mM NH4Cl. The mechanoelectrical transduction (MET) channel-mediated Ca2+ influx was measured with a scanning ion-selective microelectrode technique to reveal the function of hair cells. We found that NH4+ (≥5 mM NH4Cl) entered hair cells and suppressed the Ca2+ influx of hair cells. Neomycin and La3+ (MET channel blockers) suppressed NH4+ influx, suggesting that NH4+ enters hair cells via MET channels in hair bundles. In conclusion, this study showed that ammonia exposure (≥10 mM NH4Cl) can cause adverse effects in zebrafish embryos, and lateral-line hair cells are sensitive to ammonia exposure.
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Affiliation(s)
- Li-Yih Lin
- Department of Life Science, School of Life Science, National Taiwan Normal University, Taipei, 11677, Taiwan
| | - Jie-An Zheng
- Department of Life Science, School of Life Science, National Taiwan Normal University, Taipei, 11677, Taiwan
| | - Shun-Chih Huang
- Department of Life Science, School of Life Science, National Taiwan Normal University, Taipei, 11677, Taiwan
| | - Giun-Yi Hung
- Division of Pediatric Hematology and Oncology, Department of Pediatrics, Taipei Veterans General Hospital, Taipei, 11217, Taiwan; Department of Pediatrics, Faculty of Medicine, School of Medicine, National Yang-Ming University, Taipei, 11221, Taiwan
| | - Jiun-Lin Horng
- Department of Anatomy and Cell Biology, School of Medicine, College of Medicine, Taipei Medical University, Taipei, 11031, Taiwan.
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12
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Zimmer AM, Perry SF. The Rhesus glycoprotein Rhcgb is expendable for ammonia excretion and Na + uptake in zebrafish (Danio rerio). Comp Biochem Physiol A Mol Integr Physiol 2020; 247:110722. [PMID: 32437959 DOI: 10.1016/j.cbpa.2020.110722] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2019] [Revised: 05/01/2020] [Accepted: 05/01/2020] [Indexed: 11/27/2022]
Abstract
In zebrafish (Danio rerio), the ammonia-transporting Rhesus glycoprotein Rhcgb is implicated in mechanisms of ammonia excretion and Na+ uptake. In particular, Rhcgb is thought to play an important role in maintaining ammonia excretion in response to alkaline conditions and high external ammonia (HEA) exposure, in addition to facilitating Na+ uptake via a functional metabolon with the Na+/H+-exchanger Nhe3b, specifically under low Na+ conditions. In the present study, we hypothesized that CRISPR/Cas9 knockout of rhcgb would reduce ammonia excretion and Na+ uptake capacity, particularly under the conditions listed above that have elicited increases in Rhcgb-mediated ammonia excretion and/or Na+ uptake. Contrary to this hypothesis, however, larval and juvenile rhcgb knockout (KO) mutants showed no reductions in ammonia excretion or Na+ uptake under any of the conditions tested in our study. In fact, under control conditions, rhcgb KO mutants generally displayed an increase in ammonia excretion, potentially due to increased transcript abundance of another rh gene, rhbg. Under alkaline conditions, rhcgb KO mutants were also able to maintain ammonia excretion, similar to wild-type fish, and stimulation of ammonia excretion after HEA exposure also was not affected by rhcgb KO. Surprisingly, ammonia excretion and Na+ uptake were unaffected by rhcgb or nhe3b KO in juvenile zebrafish acclimated to normal (800 μmol/L) or low (10 μmol/L) Na+ conditions. These results demonstrate that Rhcgb is expendable for ammonia excretion and Na+ uptake in zebrafish, highlighting the plasticity and flexibility of these physiological systems in this species.
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Affiliation(s)
- Alex M Zimmer
- Department of Biological Sciences, University of Alberta, Edmonton, Alberta, Canada; Department of Biology, University of Ottawa, Ottawa, Ontario, Canada.
| | - Steve F Perry
- Department of Biology, University of Ottawa, Ottawa, Ontario, Canada
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13
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Lee CY, Horng JL, Chen PY, Lin LY. Silver nanoparticle exposure impairs ion regulation in zebrafish embryos. AQUATIC TOXICOLOGY (AMSTERDAM, NETHERLANDS) 2019; 214:105263. [PMID: 31376794 DOI: 10.1016/j.aquatox.2019.105263] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/28/2019] [Revised: 07/23/2019] [Accepted: 07/23/2019] [Indexed: 06/10/2023]
Abstract
The potential toxicity of silver nanoparticles (AgNPs) to the early stages of fish is still unclear. This study used zebrafish embryos as a model to investigate the toxic effects of AgNPs on ion regulation by skin ionocytes. Zebrafish embryos were exposed to AgNPs for 96 h (4-100 h post-fertilization (hpf)) or 4 h (96-100 hpf). After 96 h of exposure to 5 and 10 mg/L AgNPs, survival rates had decreased to 42% and 0%, respectively; the body length had also significantly decreased at 5 mg/L. Whole-body Na+ and K+ contents significantly decreased at 1 and 3 mg/L, while Ca2+ contents decreased at ≥0.1 mg/L. H+ secretion by the skin significantly decreased at 1 mg/L. The density of skin ionocytes labeled with rhodamine 123 (a mitochondrion marker) decreased by 25% and 55% at 1 and 3 mg/L, respectively; and 54% of ionocytes (at 3 mg/L) were deformed from an oval to a spinous shape. After 4 h of exposure to 1 and 5 mg/L, whole-body Na+ and Ca2+ contents, H+ secretion, and density of ionocytes had also significantly decreased. This study revealed the toxicity of AgNPs to skin ionocytes and ion regulation in the early stages of zebrafish embryos.
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Affiliation(s)
- Chih-Ying Lee
- Department of Life Science, School of Life Science, National Taiwan Normal University, Taipei, Taiwan; Division of Pediatric Hematology and Oncology, Department of Pediatrics, Taipei Veterans General Hospital, Taipei, Taiwan; Department of Pediatrics, Faculty of Medicine, School of Medicine, National Yang-Ming University, Taipei, Taiwan
| | - Jiun-Lin Horng
- Department of Anatomy and Cell Biology, School of Medicine, College of Medicine, Taipei Medical University, Taipei, Taiwan
| | - Po-Yen Chen
- Department of Life Science, School of Life Science, National Taiwan Normal University, Taipei, Taiwan
| | - Li-Yih Lin
- Department of Life Science, School of Life Science, National Taiwan Normal University, Taipei, Taiwan.
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14
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Zimmer AM, Pan YK, Chandrapalan T, Kwong RWM, Perry SF. Loss-of-function approaches in comparative physiology: is there a future for knockdown experiments in the era of genome editing? ACTA ACUST UNITED AC 2019; 222:222/7/jeb175737. [PMID: 30948498 DOI: 10.1242/jeb.175737] [Citation(s) in RCA: 34] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Loss-of-function technologies, such as morpholino- and RNAi-mediated gene knockdown, and TALEN- and CRISPR/Cas9-mediated gene knockout, are widely used to investigate gene function and its physiological significance. Here, we provide a general overview of the various knockdown and knockout technologies commonly used in comparative physiology and discuss the merits and drawbacks of these technologies with a particular focus on research conducted in zebrafish. Despite their widespread use, there is an ongoing debate surrounding the use of knockdown versus knockout approaches and their potential off-target effects. This debate is primarily fueled by the observations that, in some studies, knockout mutants exhibit phenotypes different from those observed in response to knockdown using morpholinos or RNAi. We discuss the current debate and focus on the discrepancies between knockdown and knockout phenotypes, providing literature and primary data to show that the different phenotypes are not necessarily a direct result of the off-target effects of the knockdown agents used. Nevertheless, given the recent evidence of some knockdown phenotypes being recapitulated in knockout mutants lacking the morpholino or RNAi target, we stress that results of knockdown experiments need to be interpreted with caution. We ultimately argue that knockdown experiments should not be discontinued if proper control experiments are performed, and that with careful interpretation, knockdown approaches remain useful to complement the limitations of knockout studies (e.g. lethality of knockout and compensatory responses).
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Affiliation(s)
- Alex M Zimmer
- Department of Biology, University of Ottawa, Ottawa, ON K1N 6N5, Canada
| | - Yihang K Pan
- Department of Biology, University of Ottawa, Ottawa, ON K1N 6N5, Canada
| | | | | | - Steve F Perry
- Department of Biology, University of Ottawa, Ottawa, ON K1N 6N5, Canada
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15
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Hung GY, Wu CL, Chou YL, Chien CT, Horng JL, Lin LY. Cisplatin exposure impairs ionocytes and hair cells in the skin of zebrafish embryos. AQUATIC TOXICOLOGY (AMSTERDAM, NETHERLANDS) 2019; 209:168-177. [PMID: 30784778 DOI: 10.1016/j.aquatox.2019.02.006] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/01/2018] [Revised: 02/11/2019] [Accepted: 02/11/2019] [Indexed: 06/09/2023]
Abstract
This study aimed to assess the sublethal effects of a platinum-based compound, cisplatin, using a zebrafish model. Zebrafish embryos were incubated in different concentrations of cisplatin at 0-96 h post-fertilization. Using a non-invasive, scanning ion-selective electrode technique (SIET), we measured the functions of hair cells (Ca2+ influx) and ionocytes ([H+] gradients). The survival rate, hatching rate, phenotype, body length, whole-body ion (Na+, Cl-, and Ca2+) and Pt contents were also determined. The effects of cisplatin on zebrafish embryos were demonstrated as first impairing hair cell function (at 1 μM of cisplatin), the hair cell number, and body ion content of Cl- (at 10 μM of cisplatin), then decreasing ionocyte acid secretion and overall body ion contents of Na+ and Ca2+ (at 50 μM of cisplatin). The body length and ionocyte density decreased at 100 μM of cisplatin, and survival decreased at 500 μM of cisplatin. As the cisplatin concentration increased, the accumulation of Pt in fish embryos also increased. These results revealed that hair cells are significantly more susceptible to cisplatin toxicity than ionocytes. By determining the lowest observed effective concentration of cisplatin that caused in vivo functional alterations of zebrafish hair cells and skin ionocytes, this model demonstrated 500-fold greater sensitivity than by detecting changes in survival, for early assessment of the effects of platinum-based chemotherapeutic drugs on fish.
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Affiliation(s)
- Giun-Yi Hung
- Department of Life Science, School of Life Science, National Taiwan Normal University, Taipei 11677, Taiwan; Division of Pediatric Hematology and Oncology, Department of Pediatrics, Taipei Veterans General Hospital, Taipei 11217, Taiwan; Department of Pediatrics, Faculty of Medicine, School of Medicine, National Yang-Ming University, Taipei 11221, Taiwan
| | - Ciao-Ling Wu
- Department of Life Science, School of Life Science, National Taiwan Normal University, Taipei 11677, Taiwan
| | - Yi-Ling Chou
- Department of Life Science, School of Life Science, National Taiwan Normal University, Taipei 11677, Taiwan
| | - Chiang-Ting Chien
- Department of Life Science, School of Life Science, National Taiwan Normal University, Taipei 11677, Taiwan
| | - Jiun-Lin Horng
- Department of Anatomy and Cell Biology, School of Medicine, College of Medicine, Taipei Medical University, Taipei 11042, Taiwan
| | - Li-Yih Lin
- Department of Life Science, School of Life Science, National Taiwan Normal University, Taipei 11677, Taiwan.
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16
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Durant AC, Donini A. Evidence that Rh proteins in the anal papillae of the freshwater mosquito Aedes aegypti are involved in the regulation of acid-base balance in elevated salt and ammonia environments. ACTA ACUST UNITED AC 2018; 221:jeb.186866. [PMID: 30305376 DOI: 10.1242/jeb.186866] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2018] [Accepted: 10/04/2018] [Indexed: 12/13/2022]
Abstract
Aedes aegypti commonly inhabit ammonia-rich sewage effluents in tropical regions of the world where the adults are responsible for the spread of disease. Studies have shown the importance of the anal papillae of A. aegypti in ion uptake and ammonia excretion. The anal papillae express ammonia transporters and Rhesus (Rh) proteins which are involved in ammonia excretion and studies have primarily focused on understanding these mechanisms in freshwater. In this study, effects of rearing larvae in salt (5 mmol l-1 NaCl) or ammonia (5 mmol l-1 NH4Cl) on physiological endpoints of ammonia and ion regulation were assessed. In anal papillae of NaCl-reared larvae, Rh protein expression increased, NHE3 transcript abundance decreased and NH4 + excretion increased, and this coincided with decreased hemolymph [NH4 +] and pH. We propose that under these conditions, larvae excrete more NH4 + through Rh proteins as a means of eliminating acid from the hemolymph. In anal papillae of NH4Cl-reared larvae, expression of an apical ammonia transporter and the Rh proteins decreased, the activities of NKA and VA decreased and increased, respectively, and this coincided with hemolymph acidification. The results present evidence for a role of Rh proteins in acid-base balance in response to elevated levels of salt, whereby ammonia is excreted as an acid equivalent.
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Affiliation(s)
- Andrea C Durant
- Department of Biology, York University, Toronto, ON, Canada M3J 1P3
| | - Andrew Donini
- Department of Biology, York University, Toronto, ON, Canada M3J 1P3
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17
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Zimmer AM, Wright PA, Wood CM. Ammonia and urea handling by early life stages of fishes. ACTA ACUST UNITED AC 2018; 220:3843-3855. [PMID: 29093184 DOI: 10.1242/jeb.140210] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Nitrogen metabolism in fishes has been a focus of comparative physiologists for nearly a century. In this Review, we focus specifically on early life stages of fishes, which have received considerable attention in more recent work. Nitrogen metabolism and excretion in early life differs fundamentally from that of juvenile and adult fishes because of (1) the presence of a chorion capsule in embryos that imposes a limitation on effective ammonia excretion, (2) an amino acid-based metabolism that generates a substantial ammonia load, and (3) the lack of a functional gill, which is the primary site of nitrogen excretion in juvenile and adult fishes. Recent findings have shed considerable light on the mechanisms by which these constraints are overcome in early life. Perhaps most importantly, the discovery of Rhesus (Rh) glycoproteins as ammonia transporters and their expression in ion-transporting cells on the skin of larval fishes has transformed our understanding of ammonia excretion by fishes in general. The emergence of larval zebrafish as a model species, together with genetic knockdown techniques, has similarly advanced our understanding of ammonia and urea metabolism and excretion by larval fishes. It has also now been demonstrated that ammonia excretion is one of the primary functions of the developing gill in rainbow trout larvae, leading to new hypotheses regarding the physiological demands driving gill development in larval fishes. Here, we highlight and discuss the dramatic changes in nitrogen handling that occur over early life development in fishes.
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Affiliation(s)
- Alex M Zimmer
- Department of Biology, University of Ottawa, Ottawa, ON, Canada K1N 6N57
| | - Patricia A Wright
- Department of Integrative Biology, University of Guelph, Guelph, ON, Canada N1G 2W1
| | - Chris M Wood
- Department of Zoology, University of British Columbia, Vancouver, BC, Canada V6T 1Z4.,Department of Biology, McMaster University, Hamilton, ON, Canada L8S 4K1
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18
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Potassium Regulation in Medaka (Oryzias latipes) Larvae Acclimated to Fresh Water: Passive Uptake and Active Secretion by the Skin Cells. Sci Rep 2017; 7:16215. [PMID: 29176723 PMCID: PMC5701230 DOI: 10.1038/s41598-017-16381-7] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2016] [Accepted: 11/13/2017] [Indexed: 01/29/2023] Open
Abstract
Molecular mechanisms of Na+, Cl−, and Ca2+ regulation in ionocytes of fish have been well investigated. However, the regulatory mechanism of K+ in fishes has been largely unknown. In this study, we investigated the mechanism of K+ regulation in medaka larvae acclimated to fresh water. Using a scanning ion-selective electrode technique (SIET) to measure the K+ fluxes at skin cells, significant K+ effluxes were found at ionocytes; in contrast, significant K+ influxes were found at the boundaries between keratinocytes. High K+ water (HK) acclimation induced the K+ effluxes at ionocytes and suppressed the K+ influxes at keratinocytes. The K+ effluxes of ionocytes were suppressed by VU591, bumetanide and ouabain. The K+ influxes of keratinocytes were suppressed by TAP. In situ hybridization analysis showed that mRNA of ROMKa was expressed by ionocytes in the skin and gills of medaka larvae. Quantitative PCR showed that mRNA levels of ROMKa and NKCC1a in gills of adult medaka were upregulated after HK acclimation. This study suggests that medaka obtain K+ through a paracellular pathway between keratinocytes and extrude K+ through ionocytes; apical ROMKa and basolateral NKCC1a are involved in the K+ secretion by ionocytes.
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19
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Guh YJ, Hwang PP. Insights into molecular and cellular mechanisms of hormonal actions on fish ion regulation derived from the zebrafish model. Gen Comp Endocrinol 2017; 251:12-20. [PMID: 27554927 DOI: 10.1016/j.ygcen.2016.08.009] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/29/2016] [Revised: 08/15/2016] [Accepted: 08/18/2016] [Indexed: 02/07/2023]
Abstract
Fish have sophisticated mechanisms of ionic and acid-base regulation for maintaining body fluid homeostasis. Many hormones have been proposed to control the ionic and acid-base regulation mechanisms in fishes; however, lots of the proposed actions lack convincing cellular/molecular evidence. With the advantages of available genetic databases and molecular manipulation techniques, zebrafish has become an emerging model for research into ion transport physiology and functional regulation. Different types of ionocytes were found to transport ions through various sets of ion transporters, and the molecular mechanisms of ionocyte proliferation and differentiation have also been dissected, providing a competent platform with which to precisely study the ion transport pathways and ionocytes targeted by hormones, including isotocin, prolactin, cortisol, stanniocalcin-1, calcitonin, endothelin-1, vitamin D, parathyroid hormone 1, catecholamines, the renin-angiotensin-system, estrogen-related receptor α, and calcitonin gene-related peptide, which have been demonstrated to positively or negatively regulate ion transport through specific receptors at different molecular levels (transcriptional, translational, or posttranslational) or at different developmental stages of ionocytes (proliferation or differentiation). The knowledge obtained in zebrafish not only enhances our understanding of the hormonal control of fish ion regulation, but also informs studies on other animal species, thereby providing insights into related fields.
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Affiliation(s)
- Ying-Jey Guh
- Institute of Biological Chemistry, Academia Sinica, Taipei 11529, Taiwan; Institute of Cellular and Organismic Biology, Academia Sinica, Taipei 11529, Taiwan
| | - Pung-Pung Hwang
- Institute of Cellular and Organismic Biology, Academia Sinica, Taipei 11529, Taiwan.
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20
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Talbot K, Kwong RWM, Gilmour KM, Perry SF. The water channel aquaporin-1a1 facilitates movement of CO₂ and ammonia in zebrafish (Danio rerio) larvae. ACTA ACUST UNITED AC 2017; 218:3931-40. [PMID: 26677259 DOI: 10.1242/jeb.129759] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
The present study tested the hypothesis that zebrafish (Danio rerio) aquaporin-1a1 (AQP1a1) serves as a multi-functional channel for the transfer of the small gaseous molecules, CO2 and ammonia, as well as water, across biological membranes. Zebrafish embryos were microinjected with a translation-blocking morpholino oligonucleotide targeted to AQP1a1. Knockdown of AQP1a1 significantly reduced rates of CO2 and ammonia excretion, as well as water fluxes, in larvae at 4 days post fertilization (dpf). Because AQP1a1 is expressed both in ionocytes present on the body surface and in red blood cells, the haemolytic agent phenylhydrazine was used to distinguish between the contributions of AQP1a1 to gas transfer in these two locations. Phenylhydrazine treatment had no effect on AQP1a1-linked excretion of CO2 or ammonia, providing evidence that AQP1a1 localized to the yolk sac epithelium, rather than red blood cell AQP1a1, is the major site of CO2 and ammonia movements. The possibility that AQP1a1 and the rhesus glycoprotein Rhcg1, which also serves as a dual CO2 and ammonia channel, act in concert to facilitate CO2 and ammonia excretion was explored. Although knockdown of each protein did not affect the abundance of mRNA and protein of the other protein under control conditions, impairment of ammonia excretion by chronic exposure to high external ammonia triggered a significant increase in the abundance of AQP1a1 mRNA and protein in 4 dpf larvae experiencing Rhcg1 knockdown. Collectively, these results suggest that AQP1a1 in zebrafish larvae facilitates the movement of CO2 and ammonia, as well as water, in a physiologically relevant fashion.
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Affiliation(s)
- Krystle Talbot
- Department of Biology, University of Ottawa, Ottawa, Ontario K1N 6N5, Canada
| | - Raymond W M Kwong
- Department of Biology, University of Ottawa, Ottawa, Ontario K1N 6N5, Canada
| | - Kathleen M Gilmour
- Department of Biology, University of Ottawa, Ottawa, Ontario K1N 6N5, Canada
| | - Steve F Perry
- Department of Biology, University of Ottawa, Ottawa, Ontario K1N 6N5, Canada
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21
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Chasiotis H, Ionescu A, Misyura L, Bui P, Fazio K, Wang J, Patrick M, Weihrauch D, Donini A. An animal homolog of plant Mep/Amt transporters promotes ammonia excretion by the anal papillae of the disease vector mosquito Aedes aegypti. ACTA ACUST UNITED AC 2016; 219:1346-55. [PMID: 26944496 DOI: 10.1242/jeb.134494] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2015] [Accepted: 02/22/2016] [Indexed: 12/16/2022]
Abstract
The transcripts of three putative ammonia (NH3/NH4 (+)) transporters, Rhesus-like glycoproteins AeRh50-1, AeRh50-2 and Amt/Mep-like AeAmt1 were detected in the anal papillae of larval Aedes aegypti Quantitative PCR studies revealed 12-fold higher transcript levels of AeAmt1 in anal papillae relative to AeRh50-1, and levels of AeRh50-2 were even lower. Immunoblotting revealed AeAmt1 in anal papillae as a pre-protein with putative monomeric and trimeric forms. AeAmt1 was immunolocalized to the basal side of the anal papillae epithelium where it co-localized with Na(+)/K(+)-ATPase. Ammonium concentration gradients were measured adjacent to anal papillae using the scanning ion-selective electrode technique (SIET) and used to calculate ammonia efflux by the anal papillae. dsRNA-mediated reductions in AeAmt1 decreased ammonia efflux at larval anal papillae and significantly increased ammonia levels in hemolymph, indicating a principal role for AeAmt1 in ammonia excretion. Pharmacological characterization of ammonia transport mechanisms in the anal papillae suggests that, in addition to AeAmt1, the ionomotive pumps V-type H(+)-ATPase and Na(+)/K(+)-ATPase as well as NHE3 are involved in ammonia excretion at the anal papillae.
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Affiliation(s)
- Helen Chasiotis
- Department of Biology, York University, 4700 Keele Street, Toronto, Ontario, Canada M3J 1P3
| | - Adrian Ionescu
- Department of Biology, York University, 4700 Keele Street, Toronto, Ontario, Canada M3J 1P3
| | - Lidiya Misyura
- Department of Biology, York University, 4700 Keele Street, Toronto, Ontario, Canada M3J 1P3
| | - Phuong Bui
- Department of Biology, York University, 4700 Keele Street, Toronto, Ontario, Canada M3J 1P3
| | - Kimberly Fazio
- Department of Biology, University of San Diego, 5998 Alcala Park, San Diego, CA 92110, USA
| | - Jason Wang
- Department of Biology, University of San Diego, 5998 Alcala Park, San Diego, CA 92110, USA
| | - Marjorie Patrick
- Department of Biology, University of San Diego, 5998 Alcala Park, San Diego, CA 92110, USA
| | - Dirk Weihrauch
- Department of Biological Sciences, University of Manitoba, 50 Sifton Road, Winnipeg, Manitoba, Canada R3T 2N2
| | - Andrew Donini
- Department of Biology, York University, 4700 Keele Street, Toronto, Ontario, Canada M3J 1P3
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22
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Aquaporin 1 Is Involved in Acid Secretion by Ionocytes of Zebrafish Embryos through Facilitating CO2 Transport. PLoS One 2015; 10:e0136440. [PMID: 26287615 PMCID: PMC4546062 DOI: 10.1371/journal.pone.0136440] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2015] [Accepted: 08/04/2015] [Indexed: 12/29/2022] Open
Abstract
Mammalian aquaporin 1 (AQP1) is well known to function as a membrane channel for H2O and CO2 transport. Zebrafish AQP1a.1 (the homologue of mammalian AQP1) was recently identified in ionocytes of embryos; however its role in ionocytes is still unclear. In this study, we hypothesized that zebrafish AQP1a.1 is involved in the acid secretion by ionocytes through facilitating H2O and CO2 diffusion. A real-time PCR showed that mRNA levels of AQP1a.1 in embryos were induced by exposure to 1% CO2 hypercapnia for 3 days. In situ hybridization and immunohistochemistry showed that the AQP1a.1 transcript was highly expressed by acid-secreting ionocytes, i.e., H+-ATPase-rich (HR) cells. A scanning ion-selective electrode technique (SIET) was applied to analyze CO2-induced H+ secretion by individual ionocytes in embryos. H+ secretion by HR cells remarkably increased after a transient loading of CO2 (1% for 10 min). AQP1a.1 knockdown with morpholino oligonucleotides decreased the H+ secretion of HR cells by about half and limited the CO2 stimulated increase. In addition, exposure to an AQP inhibitor (PCMB) for 10 min also suppressed CO2-induced H+ secretion. Results from this study support our hypothesis and provide in vivo evidence of the physiological role of AQP1 in CO2 transport.
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23
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Guh YJ, Lin CH, Hwang PP. Osmoregulation in zebrafish: ion transport mechanisms and functional regulation. EXCLI JOURNAL 2015; 14:627-59. [PMID: 26600749 PMCID: PMC4650948 DOI: 10.17179/excli2015-246] [Citation(s) in RCA: 48] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/30/2015] [Accepted: 04/21/2015] [Indexed: 12/21/2022]
Abstract
Fish, like mammals, have to maintain their body fluid ionic and osmotic homeostasis through sophisticated iono-/osmoregulation mechanisms, which are conducted mainly by ionocytes of the gill (the skin in embryonic stages), instead of the renal tubular cells in mammals. Given the advantages in terms of genetic database availability and manipulation, zebrafish is an emerging model for research into regulatory and integrative physiology. At least five types of ionocytes, HR, NaR, NCC, SLC26, and KS cells, have been identified to carry out Na(+) uptake/H(+) secretion/NH4 (+) excretion, Ca(2+) uptake, Na(+)/Cl(-) uptake, K(+) secretion, and Cl(-) uptake/HCO3 (-) secretion, respectively, through distinct sets of transporters. Several hormones, namely isotocin, prolactin, cortisol, stanniocalcin-1, calcitonin, endothelin-1, vitamin D, parathyorid hormone 1, catecholamines, and the renin-angiotensin-system, have been demonstrated to positively or negatively regulate ion transport through specific receptors at different ionocytes stages, at either the transcriptional/translational or posttranslational level. The knowledge obtained using zebrafish answered many long-term contentious or unknown issues in the field of fish iono-/osmoregulation. The homology of ion transport pathways and hormone systems also means that the zebrafish model informs studies on mammals or other animal species, thereby providing insights into related fields.
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Affiliation(s)
- Ying-Jey Guh
- Institute of Cellular and Organismic Biology, Academia Sinica, Nakang, Taipei, Taiwan ; Institute of Biological Chemistry, Academia Sinica, Nakang, Taipei, Taiwan
| | - Chia-Hao Lin
- National Institute for Basic Biology, Myodaiji-cho, Okazaki, 444-8787, Japan
| | - Pung-Pung Hwang
- Institute of Cellular and Organismic Biology, Academia Sinica, Nakang, Taipei, Taiwan
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24
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Furukawa F, Tseng YC, Liu ST, Chou YL, Lin CC, Sung PH, Uchida K, Lin LY, Hwang PP. Induction of Phosphoenolpyruvate Carboxykinase (PEPCK) during Acute Acidosis and Its Role in Acid Secretion by V-ATPase-Expressing Ionocytes. Int J Biol Sci 2015; 11:712-25. [PMID: 25999794 PMCID: PMC4440261 DOI: 10.7150/ijbs.11827] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2015] [Accepted: 04/09/2015] [Indexed: 12/21/2022] Open
Abstract
Vacuolar-Type H+-ATPase (V-ATPase) takes the central role in pumping H+ through cell membranes of diverse organisms, which is essential for surviving acid-base fluctuating lifestyles or environments. In mammals, although glucose is believed to be an important energy source to drive V-ATPase, and phosphoenolpyruvate carboxykinase (PEPCK), a key enzyme for gluconeogenesis, is known to be activated in response to acidosis, the link between acid secretion and PEPCK activation remains unclear. In the present study, we used zebrafish larva as an in vivo model to show the role of acid-inducible PEPCK activity in glucose production to support higher rate of H+ secretion via V-ATPase, by utilizing gene knockdown, glucose supplementation, and non-invasive scanning ion-selective electrode technique (SIET). Zebrafish larvae increased V-ATPase-mediated acid secretion and transiently expression of Pck1, a zebrafish homolog of PEPCK, in response to acid stress. When pck1 gene was knocked down by specific morpholino, the H+ secretion via V-ATPase decreased, but this effect was rescued by supplementation of glucose into the yolk. By assessing changes in amino acid content and gene expression of respective enzymes, glutamine and glutamate appeared to be the major source for replenishment of Krebs cycle intermediates, which are subtracted by Pck1 activity. Unexpectedly, pck1 knockdown did not affect glutamine/glutamate catalysis, which implies that Pck1 does not necessarily drive this process. The present study provides the first in vivo evidence that acid-induced PEPCK provides glucose for acid-base homeostasis at an individual level, which is supported by rapid pumping of H+ via V-ATPase at the cellular level.
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Affiliation(s)
- Fumiya Furukawa
- 1. Institute of Cellular and Organismic Biology, Academia Sinica, Nankang, Taipei, Taiwan ; 2. Department of Marine Biology and Environmental Sciences, Faculty of Agriculture, University of Miyazaki, Miyazaki, Japan
| | - Yung-Che Tseng
- 3. Department of Life Science, National Taiwan Normal University, Taipei, Taiwan
| | - Sian-Tai Liu
- 3. Department of Life Science, National Taiwan Normal University, Taipei, Taiwan
| | - Yi-Ling Chou
- 1. Institute of Cellular and Organismic Biology, Academia Sinica, Nankang, Taipei, Taiwan
| | - Ching-Chun Lin
- 1. Institute of Cellular and Organismic Biology, Academia Sinica, Nankang, Taipei, Taiwan
| | - Po-Hsuan Sung
- 4. Department of Life Science, National Taiwan University, Taipei, Taiwan
| | - Katsuhisa Uchida
- 2. Department of Marine Biology and Environmental Sciences, Faculty of Agriculture, University of Miyazaki, Miyazaki, Japan
| | - Li-Yih Lin
- 3. Department of Life Science, National Taiwan Normal University, Taipei, Taiwan
| | - Pung-Pung Hwang
- 1. Institute of Cellular and Organismic Biology, Academia Sinica, Nankang, Taipei, Taiwan
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25
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Edwards SL, Arnold J, Blair SD, Pray M, Bradley R, Erikson O, Walsh PJ. Ammonia excretion in the Atlantic hagfish (Myxine glutinosa) and responses of an Rhc glycoprotein. Am J Physiol Regul Integr Comp Physiol 2015; 308:R769-78. [DOI: 10.1152/ajpregu.00355.2014] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2014] [Accepted: 02/20/2015] [Indexed: 12/21/2022]
Abstract
Hagfishes, the most ancient of the extant craniates, demonstrate a high tolerance for a number of unfavorable environmental conditions, including elevated ammonia. Proposed mechanisms of ammonia excretion in aquatic organisms include vesicular NH4+ transport and release by exocytosis in marine crabs, and passive NH3 diffusion, active NH4+ transport, and paracellular leakage of NH3 or NH4+ across the gills of fishes. Recently, an emerging paradigm suggests that Rhesus glycoproteins play a vital role in ammonia transport in both aquatic invertebrates and vertebrates. This study has identified an Rh glycoprotein ortholog from the gills of Atlantic hagfish. The hagfish Rhcg shares a 56–60% amino acid identity to other vertebrate Rhcg cDNAs. Sequence information was used to produce an anti-hagfish Rhcg (hRhcg) antibody. We have used hRhcg to localize protein expression to epithelial cells of the gill and the skin. In addition, we have quantified hRhcg expression following exposure to elevated plasma ammonia levels. Animals exposed to a 3 mmol/kg NH4Cl load resulted in significantly elevated plasma ammonia concentrations compared with controls for up to 4 h postinjection. This correlated with net ammonia excretion rates that were also significantly elevated for up to 4 h postinjection. Rhcg mRNA expression in both the gill and skin was significantly elevated by 15 min and 1 h, respectively, and hRhcg protein expression in gills was significantly elevated at 2, 4, and 8 h postinjection. These results demonstrate a potential role for Rhcg in the excretion of ammonia in the Atlantic hagfish.
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Affiliation(s)
- Susan L. Edwards
- Department of Biology, Appalachian State University, Boone, North Carolina
- Mount Desert Island Biological Laboratory, Salisbury Cove, Maine; and
| | - Justin Arnold
- Department of Biology, Appalachian State University, Boone, North Carolina
- Mount Desert Island Biological Laboratory, Salisbury Cove, Maine; and
| | - Salvatore D. Blair
- Department of Biology, Appalachian State University, Boone, North Carolina
- Mount Desert Island Biological Laboratory, Salisbury Cove, Maine; and
| | - Margaret Pray
- Department of Biology, Appalachian State University, Boone, North Carolina
- Mount Desert Island Biological Laboratory, Salisbury Cove, Maine; and
| | - Rachel Bradley
- Department of Biology, Appalachian State University, Boone, North Carolina
- Mount Desert Island Biological Laboratory, Salisbury Cove, Maine; and
| | - Olivia Erikson
- Mount Desert Island Biological Laboratory, Salisbury Cove, Maine; and
| | - Patrick J. Walsh
- Department of Biology, University of Ottawa, Ottawa, Ontario, Canada
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26
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Sandberg K, Verbalis JG, Yosten GLC, Samson WK. Sex and basic science. A Title IX position. Am J Physiol Regul Integr Comp Physiol 2014; 307:R361-5. [PMID: 24944252 PMCID: PMC5504397 DOI: 10.1152/ajpregu.00251.2014] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Affiliation(s)
- Kathryn Sandberg
- Center for the Study of Sex Differences in Health, Aging and Disease and Department of Medicine, Georgetown University, Washington, DC; and
| | - Joseph G Verbalis
- Center for the Study of Sex Differences in Health, Aging and Disease and Department of Medicine, Georgetown University, Washington, DC; and
| | - Gina L C Yosten
- Department of Pharmacological and Physiological Science, Saint Louis University, Saint Louis, Missouri
| | - Willis K Samson
- Department of Pharmacological and Physiological Science, Saint Louis University, Saint Louis, Missouri
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27
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Zimmer AM, Brauner CJ, Wood CM. Exposure to waterborne Cu inhibits cutaneous Na⁺ uptake in post-hatch larval rainbow trout (Oncorhynchus mykiss). AQUATIC TOXICOLOGY (AMSTERDAM, NETHERLANDS) 2014; 150:151-158. [PMID: 24680751 DOI: 10.1016/j.aquatox.2014.03.001] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/21/2014] [Revised: 02/24/2014] [Accepted: 03/02/2014] [Indexed: 06/03/2023]
Abstract
In freshwater rainbow trout (Oncorhynchus mykiss), two common responses to acute waterborne copper (Cu) exposure are reductions in ammonia excretion and Na(+) uptake at the gills, with the latter representing the likely lethal mechanism of action for Cu in adult fish. Larval fish, however, lack a functional gill following hatch and rely predominantly on cutaneous exchange, yet represent the most Cu-sensitive life stage. It is not known if Cu toxicity in larval fish occurs via the skin or gills. The present study utilized divided chambers to assess cutaneous and branchial Cu toxicity over larval development, using disruptions in ammonia excretion (Jamm) and Na(+) uptake (Jin(Na)) as toxicological endpoints. Early in development (early; 3 days post-hatch; dph), approximately 95% of Jamm and 78% of Jin(Na) occurred cutaneously, while in the late developmental stage (late; 25 dph), the gills were the dominant site of exchange (83 and 87% of Jamm and Jin(Na), respectively). Exposure to 50 μg/l Cu led to a 49% inhibition of Jamm in the late developmental stage only, while in the early and middle developmental (mid; 17 dph) stages, Cu had no effect on Jamm. Jin(Na), however, was significantly inhibited by Cu exposure at the early (53% reduction) and late (47% reduction) stages. Inhibition at the early stage of development was mediated by a reduction in cutaneous uptake, representing the first evidence of cutaneous metal toxicity in an intact aquatic organism. The inhibitions of both Jamm and Jin(Na) in the late developmental stage occurred via a reduction in branchial exchange only. The differential responses of the skin and gills to Cu exposure suggest that the mechanisms of Jamm and Jin(Na) and/or Cu toxicity differ between these tissues. Exposure to 20μg/l Cu revealed that Jamm is the more Cu-sensitive process. The results presented here have important implications in predicting metal toxicity in larval fish. The Biotic Ligand Model (BLM) is currently used to predict metal toxicity in aquatic organisms. However, for rainbow trout this is based on gill binding constants from juvenile fish. This may not be appropriate for post-hatch larval fish where the skin is the site of toxic action of Cu. Determining Cu binding constants and lethal accumulation concentrations for both skin and gills in larval fish may aid in developing a larval fish-specific BLM. Overall, the changing site of toxic action and physiology of developing larval fish present an interesting and exciting avenue for future research.
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Affiliation(s)
- Alex M Zimmer
- Department of Biology, McMaster University, Hamilton, ON, Canada L8S 4K1; Department of Zoology, University of British Columbia, Vancouver, BC, Canada V6T 1Z4.
| | - Colin J Brauner
- Department of Zoology, University of British Columbia, Vancouver, BC, Canada V6T 1Z4.
| | - Chris M Wood
- Department of Biology, McMaster University, Hamilton, ON, Canada L8S 4K1; Department of Zoology, University of British Columbia, Vancouver, BC, Canada V6T 1Z4.
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28
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Cruz SA, Lin CH, Chao PL, Hwang PP. Glucocorticoid receptor, but not mineralocorticoid receptor, mediates cortisol regulation of epidermal ionocyte development and ion transport in zebrafish (danio rerio). PLoS One 2013; 8:e77997. [PMID: 24205060 PMCID: PMC3812134 DOI: 10.1371/journal.pone.0077997] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2013] [Accepted: 09/08/2013] [Indexed: 12/25/2022] Open
Abstract
Cortisol is the major endogenous glucocorticoid (GC) both in human and fish, mediated by corticosteroid receptors. Due to the absence of aldosterone production in teleost fish, cortisol is also traditionally accepted to function as mineralocorticoid (MC); but whether it acts through the glucocorticoid receptor (GR) or the mineralocorticoid receptor (MR) remains a subject of debate. Here, we used loss-of-function and rescue assays to determine whether cortisol affects zebrafish epidermal ionocyte development and function via the GR and/or the MR. GR knockdown morphants displayed a significant decrease in the major ionocytes, namely Na(+)-K(+)-ATPase-rich cells (NaRCs) and H(+)-ATPase-rich cells (HRCs), as well as other cells, including epidermal stem cells (ESCs), keratinocytes, and mucus cells; conversely, cell numbers were unaffected in MR knockdown morphants. In agreement, GR morphants, but not MR morphants, exhibited decreased NaRC-mediated Ca(2+) uptake and HRC-mediated H(+) secretion. Rescue via GR capped mRNA injection or exogenous cortisol incubation normalized the number of epidermal ionocytes in GR morphants. We also provide evidence for GR localization in epidermal cells. At the transcript level, GR mRNA is ubiquitously expressed in gill sections and present in both NaRCs and HRCs, supporting the knockdown and functional assay results in embryo. Altogether, we have provided solid molecular evidence that GR is indeed present on ionocytes, where it mediates the effects of cortisol on ionocyte development and function. Hence, cortisol-GR axis performs the roles of both GC and MC in zebrafish skin and gills.
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Affiliation(s)
- Shelly Abad Cruz
- Institute of Cellular and Organismic Biology, Academia Sinica, Nankang, Taipei, Taiwan, R. O. C
| | - Chia-Hao Lin
- Institute of Cellular and Organismic Biology, Academia Sinica, Nankang, Taipei, Taiwan, R. O. C
| | - Pei-Lin Chao
- Institute of Cellular and Organismic Biology, Academia Sinica, Nankang, Taipei, Taiwan, R. O. C
| | - Pung-Pung Hwang
- Institute of Cellular and Organismic Biology, Academia Sinica, Nankang, Taipei, Taiwan, R. O. C
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