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Kovac A, Goss GG. Cellular mechanisms of ion and acid-base regulation in teleost gill ionocytes. J Comp Physiol B 2024:10.1007/s00360-024-01560-6. [PMID: 38761226 DOI: 10.1007/s00360-024-01560-6] [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: 01/21/2024] [Revised: 04/16/2024] [Accepted: 04/27/2024] [Indexed: 05/20/2024]
Abstract
The mechanism(s) of sodium, chloride and pH regulation in teleost fishes has been the subject of intense interest for researchers over the past 100 years. The primary organ responsible for ionoregulatory homeostasis is the gill, and more specifically, gill ionocytes. Building on the theoretical and experimental research of the past, recent advances in molecular and cellular techniques in the past two decades have allowed for substantial advances in our understanding of mechanisms involved. With an increased diversity of teleost species and environmental conditions being investigated, it has become apparent that there are multiple strategies and mechanisms employed to achieve ion and acid-base homeostasis. This review will cover the historical developments in our understanding of the teleost fish gill, highlight some of the recent advances and conflicting information in our understanding of ionocyte function, and serve to identify areas that require further investigation to improve our understanding of complex cellular and molecular machineries involved in iono- and acid-base regulation.
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Affiliation(s)
- Anthony Kovac
- Department of Biological Sciences, University of Alberta, Edmonton, AB, T6G 2E9, Canada
| | - Greg G Goss
- Department of Biological Sciences, University of Alberta, Edmonton, AB, T6G 2E9, 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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Retention of ion channel genes expression increases Japanese medaka survival during seawater reacclimation. J Comp Physiol B 2023; 193:81-93. [PMID: 36264377 DOI: 10.1007/s00360-022-01465-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/11/2022] [Indexed: 01/24/2023]
Abstract
Euryhaline teleosts exhibit varying acclimability to survive in environments that alternate between being hypotonic and hypertonic. Such ability is conferred by ion channels expressed by ionocytes, the ion-regulating cells in the gills or skin. However, switching between environments is physiologically challenging, because most channels can only perform unidirectional ion transportation. Coordination between acute responses, such as gene expression, and long-term responses, such as cell differentiation, is believed to strongly facilitate adaptability. Moreover, the pre-acclimation to half seawater salinity can improve the survivability of Japanese medaka (Oryzias latipes) during direct transfer to seawater; here, the ionocytes preserve hypertonic acclimability while performing hypotonic functions. Whether acclimability can be similarly induced in a closed species and their corresponding responses in terms of ion channel expression remain unclear. In the present study, Japanese medaka pre-acclimated in brackish water were noted to have higher survival rates while retaining higher expression of the three ion channel genes ATP1a1a.1, ATP1b1b, and SLC12a2a. This retention was maintained up to 2 weeks after the fish were transferred back into freshwater. Notably, this induced acclimability was not found in its close kin, Indian medaka (Oryzias dancena), the natural habitat of which is brackish water. In conclusion, Japanese medaka surpassed Indian medaka in seawater acclimability after experiencing exposure to brackish water, and this ability coincided with seawater-retention gene expression.
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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: 0] [Impact Index Per Article: 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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Acute Stress in Lesser-Spotted Catshark (Scyliorhinus canicula Linnaeus, 1758) Promotes Amino Acid Catabolism and Osmoregulatory Imbalances. Animals (Basel) 2022; 12:ani12091192. [PMID: 35565621 PMCID: PMC9105869 DOI: 10.3390/ani12091192] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2022] [Revised: 04/27/2022] [Accepted: 05/04/2022] [Indexed: 11/30/2022] Open
Abstract
Simple Summary In catsharks (Scyliorhinus canicula), air exposure induces amino acid catabolism altogether with osmoregulatory imbalances. This study describes a novel NHE isoform being expressed in gills that may be involved in ammonium excretion. Abstract Acute-stress situations in vertebrates induce a series of physiological responses to cope with the event. While common secondary stress responses include increased catabolism and osmoregulatory imbalances, specific processes depend on the taxa. In this sense, these processes are still largely unknown in ancient vertebrates such as marine elasmobranchs. Thus, we challenged the lesser spotted catshark (Scyliorhinus canicula) to 18 min of air exposure, and monitored their recovery after 0, 5, and 24 h. This study describes amino acid turnover in the liver, white muscle, gills, and rectal gland, and plasma parameters related to energy metabolism and osmoregulatory imbalances. Catsharks rely on white muscle amino acid catabolism to face the energy demand imposed by the stressor, producing NH4+. While some plasma ions (K+, Cl− and Ca2+) increased in concentration after 18 min of air exposure, returning to basal values after 5 h of recovery, Na+ increased after just 5 h of recovery, coinciding with a decrease in plasma NH4+. These changes were accompanied by increased activity of a branchial amiloride-sensitive ATPase. Therefore, we hypothesize that this enzyme may be a Na+/H+ exchanger (NHE) related to NH4+ excretion. The action of an omeprazole-sensitive ATPase, putatively associated to a H+/K+-ATPase (HKA), is also affected by these allostatic processes. Some complementary experiments were carried out to delve a little deeper into the possible branchial enzymes sensitive to amiloride, including in vivo and ex vivo approaches, and partial sequencing of a nhe1 in the gills. This study describes the possible presence of an HKA enzyme in the rectal gland, as well as a NHE in the gills, highlighting the importance of understanding the relationship between acute stress and osmoregulation in elasmobranchs.
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Shih SW, Yan JJ, Tsou YL, Lu SW, Wang MC, Chou MY, Hwang PP. In Vivo Functional Assay in Fish Gills: Exploring Branchial Acid-Excreting Mechanisms in Zebrafish. Int J Mol Sci 2022; 23:ijms23084419. [PMID: 35457237 PMCID: PMC9031880 DOI: 10.3390/ijms23084419] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2022] [Revised: 04/13/2022] [Accepted: 04/14/2022] [Indexed: 02/06/2023] Open
Abstract
Molecular and physiological analyses in ionoregulatory organs (e.g., adult gills and embryonic skin) are essential for studying fish ion regulation. Recent progress in the molecular physiology of fish ion regulation was mostly obtained in embryonic skin; however, studies of ion regulation in adult gills are still elusive and limited because there are no direct methods for in vivo functional assays in the gills. The present study applied the scanning ion-selective electrode technique (SIET) in adult gills to investigate branchial H+-excreting functions in vivo. We removed the opercula from zebrafish and then performed long-term acid acclimation experiments. The results of Western blot and immunofluorescence showed that the protein expression of H+-ATPase (HA) and the number of H+-ATPase-rich ionocytes were increased under acidic situations. The SIET results proved that the H+ excretion capacity is indeed enhanced in the gills acclimated to acidic water. In addition, both HA and Na+/H+ exchanger (Nhe) inhibitors suppressed the branchial H+ excretion capacity, suggesting that H+ is excreted in association with HA and Nhe in zebrafish gills. These results demonstrate that SIET is effective for in vivo detection in fish gills, representing a breakthrough approach for studying the molecular physiology of fish ion regulation.
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Affiliation(s)
- Shang-Wu Shih
- Institute of Cellular and Organismic Biology, Academia Sinica, Taipei 11529, Taiwan; (S.-W.S.); (J.-J.Y.); (Y.-L.T.); (S.-W.L.); (M.-C.W.)
- Department of Life Science, National Taiwan University, Taipei 10617, Taiwan;
| | - Jia-Jiun Yan
- Institute of Cellular and Organismic Biology, Academia Sinica, Taipei 11529, Taiwan; (S.-W.S.); (J.-J.Y.); (Y.-L.T.); (S.-W.L.); (M.-C.W.)
| | - Yi-Ling Tsou
- Institute of Cellular and Organismic Biology, Academia Sinica, Taipei 11529, Taiwan; (S.-W.S.); (J.-J.Y.); (Y.-L.T.); (S.-W.L.); (M.-C.W.)
| | - Shao-Wei Lu
- Institute of Cellular and Organismic Biology, Academia Sinica, Taipei 11529, Taiwan; (S.-W.S.); (J.-J.Y.); (Y.-L.T.); (S.-W.L.); (M.-C.W.)
| | - Min-Chen Wang
- Institute of Cellular and Organismic Biology, Academia Sinica, Taipei 11529, Taiwan; (S.-W.S.); (J.-J.Y.); (Y.-L.T.); (S.-W.L.); (M.-C.W.)
| | - Ming-Yi Chou
- Department of Life Science, National Taiwan University, Taipei 10617, Taiwan;
| | - Pung-Pung Hwang
- Institute of Cellular and Organismic Biology, Academia Sinica, Taipei 11529, Taiwan; (S.-W.S.); (J.-J.Y.); (Y.-L.T.); (S.-W.L.); (M.-C.W.)
- Department of Life Science, National Taiwan University, Taipei 10617, Taiwan;
- Correspondence:
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7
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Liu ST, Horng JL, Lin LY. Role of the Basolateral Na+/H+ Exchanger-2 (NHE2) in Ionocytes of Seawater- Acclimated Medaka (Oryzias latipes). Front Physiol 2022; 13:870967. [PMID: 35399277 PMCID: PMC8987715 DOI: 10.3389/fphys.2022.870967] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2022] [Accepted: 02/28/2022] [Indexed: 12/03/2022] Open
Abstract
Ionocytes in the skin and gills of seawater (SW) fishes are responsible for acid-base regulation and salt secretion. Na+/H+ exchangers (NHEs) are considered the major acid (H+)-secreting transporters in ionocytes of SW fishes. However, the subcellular localization and function of a specific NHE isoform (NHE2) have never clearly been revealed. In this study, we cloned and sequenced NHE2 from an SW-acclimated medaka (Oryzias latipes) and examined its functions in medaka embryos. A phylogenetic analysis showed that the evolutionary relationships of mammalian NHE2 and NHE4 are close to those of fish NHE2. A gene structure analysis showed that tetrapod NHE4 might be a tandem duplication of fish NHE2. Immunohistochemistry with a medaka-specific antibody localized NHE2 to the basolateral membrane of ionocytes. Lost-of-function experiments with photo-activated morpholino oligonucleotides showed that both H+ and Cl– secretion by ionocytes were suppressed in NHE2-knockdown embryos, suggesting that the basolateral NHE2 facilitates acid and salt secretion by ionocytes of medaka in seawater.
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Affiliation(s)
- Sian-Tai Liu
- Department of Life Science, School of Life Sciences, National Taiwan Normal University, Taipei City, Taiwan
| | - Jiun-Lin Horng
- Department of Anatomy and Cell Biology, School of Medicine, College of Medicine, Taipei Medical University, Taipei City, Taiwan
| | - Li-Yih Lin
- Department of Life Science, School of Life Sciences, National Taiwan Normal University, Taipei City, Taiwan
- *Correspondence: Li-Yih Lin,
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8
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Chang YM, Zhao XF, Liew HJ, Sun B, Wang SY, Luo L, Zhang LM, Liang LQ. Effects of Bicarbonate Stress on Serum Ions and Gill Transporters in Alkali and Freshwater Forms of Amur Ide ( Leuciscus waleckii). Front Physiol 2021; 12:676096. [PMID: 34594232 PMCID: PMC8476968 DOI: 10.3389/fphys.2021.676096] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2021] [Accepted: 08/19/2021] [Indexed: 11/30/2022] Open
Abstract
The Amur ide (Leuciscus waleckii) is a fish in the Cyprinidae family. Compared with other Amur ide living in freshwater ecosystems, the Amur ide population in Lake Dali Nor of China is famous for its high tolerance to the alkaline conditions of 54 mM (pH 9.6). Yet, surprisingly, the ionoregulatory mechanism responsible for this remarkable alkaline adaptation remains unclear. Therefore, this study sought to investigate how bicarbonate affects the acid-base balancing and ionoregulatory responses of this animal. Here, using a comparative approach, the alkali form of Amur ide and its ancestral freshwater form living in other freshwater basins were each exposed to 50 mM (pH 9.59 ± 0.09), a level close to the alkalinity of Lake Dali Nor, and their physiological (AE1) adjustment of ions and acid-base regulation were investigated. This study highlighted differences in blood pH and serum ions (e.g., Na+, K+, Cl−, and Ca2+), Na+/K+ ATPase (NKA) activity and its mRNA level, and mRNA expression of gill transporters (Na+/H+ exchanger member 2 and/or 3, Na+/HCO3- cotransporter (NBC1), Cl−/HCO3- exchanger, Na+/Cl− cotransporter (NCC), Na+/K+/2Cl− (NKCC1), SLC26A5, and SLC26A6) for alkalinity adaptation between the two forms of Amur ide differing in alkalinity tolerance. Specifically, close relationships among the serum Na+ and mRNA levels of NCC, NKCC1, and NHE, and also NKA and NBC1, in addition to serum Cl− and bicarbonate transporters (e.g., SLC26A5 and SLC26A6), characterized the alkali form of Amur ide. We propose that this ecotype can ensure its transepithelial Cl− and Na+ uptake/base secretions are highly functional, by its basolateral NKA with NBC1 and apical ionic transporters, and especially NCC incorporated with other transporters (e.g., SLC26). This suggests an evolved strong ability to maintain an ion osmotic and acid-base balance for more effectively facilitating its adaptability to the high alkaline environment. This study provides new insights into the physiological responses of the alkaline form of the Amur ide fish for adapting to extreme alkaline conditions. This information could be used as a reference to cultivating alkaline-tolerant fish species in abandoned alkaline waters.
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Affiliation(s)
- Yu Mei Chang
- National and Local Joint Engineering Laboratory for Freshwater Fish Breeding, Heilongjiang River Fisheries Research Institute, Chinese Academy of Fishery Sciences, Harbin, China
| | - Xue Fei Zhao
- National and Local Joint Engineering Laboratory for Freshwater Fish Breeding, Heilongjiang River Fisheries Research Institute, Chinese Academy of Fishery Sciences, Harbin, China.,College of Wildlife and Protected Area, Northeast Forestry University, Harbin, China
| | - Hon Jung Liew
- National and Local Joint Engineering Laboratory for Freshwater Fish Breeding, Heilongjiang River Fisheries Research Institute, Chinese Academy of Fishery Sciences, Harbin, China.,Higher Institution of Center Excellence, Institute of Tropical Aquaculture and Fisheries, Faculty of Fisheries and Food Science, Universiti Malaysia Terengganu, Kuala Nerus, Malaysia
| | - Bo Sun
- National and Local Joint Engineering Laboratory for Freshwater Fish Breeding, Heilongjiang River Fisheries Research Institute, Chinese Academy of Fishery Sciences, Harbin, 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, China.,College of Fisheries and Life Science, Shanghai Ocean University, Shanghai, China
| | - Liang Luo
- National and Local Joint Engineering Laboratory for Freshwater Fish Breeding, Heilongjiang River Fisheries Research Institute, Chinese Academy of Fishery Sciences, Harbin, 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, 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, China
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Hung GY, Chen PY, Horng JL, Lin LY. Vincristine exposure impairs skin keratinocytes, ionocytes, and lateral-line hair cells in developing zebrafish embryos. AQUATIC TOXICOLOGY (AMSTERDAM, NETHERLANDS) 2021; 230:105703. [PMID: 33249295 DOI: 10.1016/j.aquatox.2020.105703] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/31/2020] [Revised: 11/18/2020] [Accepted: 11/19/2020] [Indexed: 06/12/2023]
Abstract
Environmental contamination by anticancer pharmaceuticals has been widely reported. These drugs are not readily biodegradable, and their parent compounds and/or metabolites have been detected in surface waters and groundwater throughout the world. Adverse effects of anticancer drugs occur frequently in cancer patients, and a large body of clinical knowledge has accumulated. However, the effects of these drugs on aquatic organisms have not been thoroughly studied. This study aimed to investigate the effects of acute exposure to a common anticancer drug, vincristine (VCR), on zebrafish embryonic development and skin function. After 96 h of VCR exposure (0, 1, 10, 15, and 25 mg/L), significant teratogenic effects were observed, including growth retardation, pericardial edema, spine, tail, and yolk sac malformations (VCR ≥ 15 mg/L), a decreased heart rate, and ocular malformations (VCR ≥ 10 mg/L). The value of the half lethal concentration for zebrafish embryos was 20.6 mg/L. At ≥10 mg/L VCR, systemic ion contents and acid secretion in the skin over the yolk-sac decreased, and these findings were associated with decreases in skin ionocytes (H+-ATPase-rich cells and Na+-K+-ATPase-rich cells). Also, the microridge-structure of skin keratinocytes was significantly damaged. The number of lateral line hair cells was reduced when VCR was ≥10 mg/L, and functional impairment was detected when VCR was as low as 1 mg/L. Results of this in vivo study in zebrafish embryos indicate that acute exposure to VCR can lead to developmental defects, impairment of skin functions, and even fish death.
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Affiliation(s)
- Giun-Yi Hung
- Division of Pediatric Hematology and Oncology, Department of Pediatrics, Taipei Veterans General Hospital, 201 Shih-Pai Road, Sec. 2, Taipei 11217, Taiwan; Faculty of Medicine, School of Medicine, National Yang-Ming University, 155 Linong St., Sec. 2, Taipei 11221, Taiwan; Department of Life Science, School of Life Science, National Taiwan Normal University, 88 Ting-Chow Rd., Sec. 4, Taipei 11677, Taiwan.
| | - Po-Yen Chen
- Department of Anatomy and Cell Biology, School of Medicine, College of Medicine, Taipei Medical University, 250 Wuxing St., Taipei 11031, Taiwan.
| | - Jiun-Lin Horng
- Department of Anatomy and Cell Biology, School of Medicine, College of Medicine, Taipei Medical University, 250 Wuxing St., Taipei 11031, Taiwan.
| | - Li-Yih Lin
- Department of Life Science, School of Life Science, National Taiwan Normal University, 88 Ting-Chow Rd., Sec. 4, Taipei 11677, Taiwan.
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10
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Yao Z, Schauer KL, Ruhr IM, Mager EM, Heuer RM, Grosell M. A marine teleost, Opsanus beta, compensates acidosis in hypersaline water by H + excretion or reduced HCO 3- excretion rather than HCO 3- uptake. J Comp Physiol B 2020; 191:85-98. [PMID: 33070210 DOI: 10.1007/s00360-020-01320-2] [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: 02/10/2020] [Revised: 09/10/2020] [Accepted: 09/29/2020] [Indexed: 10/23/2022]
Abstract
Increases in ambient salinity demand parallel increases in intestinal base secretion for maintenance of osmoregulatory status, which is likely the cause of a transient acidosis following transfer of euryhaline fish from freshwater to seawater. It was predicted that transfer of the marine Gulf toadfish (Opsanus beta) from seawater (35 ppt) to hypersaline (60 ppt) seawater (HSW) would lead to a transient acidosis that would be compensated by increases in branchial acid excretion to offset the acid-base disturbance. Toadfish exposed to HSW showed a significant decrease in blood pH and [HCO3-] but no increase in pCO2, followed by a full recovery after 48-96 h. A similar metabolic acidosis and recovery was found when fish were exposed to 60-ppt HCO3--free seawater (HEPES-buffered), which may suggest that compensation for intestinal base loss during hypersaline treatment is from gill H+ excretion rather than gill HCO3- uptake. However, we cannot rule out that reduced branchial HCO3- excretion contributed to an increase in net acid excretion. Since colchicine prevents full compensation, translocation of H+ and/or HCO3- transporters between cytosolic compartments and plasma membrane fractions might be involved in compensating for the hypersalinity-induced acidosis. Translocation of transporters rather than de novo synthesis may represent a faster and less energetically demanding response to rapidly fluctuating and high salinities encountered by toadfish in their natural environment.
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Affiliation(s)
- Zongli Yao
- Sino-US joint laboratory of Aquatic Animal Physiology, East China Sea Fisheries Research Institute, Chinese Academy of Fisheries Sciences, Shanghai, China. .,Department of Marine Biology and Ecology, Rosenstiel School of Marine and Atmospheric Science, University of Miami, Miami, FL, USA.
| | - Kevin L Schauer
- Department of Marine Biology and Ecology, Rosenstiel School of Marine and Atmospheric Science, University of Miami, Miami, FL, USA
| | - Ilan M Ruhr
- Department of Marine Biology and Ecology, Rosenstiel School of Marine and Atmospheric Science, University of Miami, Miami, FL, USA.,Cardiovascular Sciences, School of Medical Sciences, The University of Manchester, Manchester, UK
| | - Edward M Mager
- Department of Marine Biology and Ecology, Rosenstiel School of Marine and Atmospheric Science, University of Miami, Miami, FL, USA.,Department of Biological Sciences, University of North Texas, Denton, TX, USA
| | - Rachael M Heuer
- Department of Marine Biology and Ecology, Rosenstiel School of Marine and Atmospheric Science, University of Miami, Miami, FL, USA
| | - Martin Grosell
- Sino-US joint laboratory of Aquatic Animal Physiology, East China Sea Fisheries Research Institute, Chinese Academy of Fisheries Sciences, Shanghai, China.,Department of Marine Biology and Ecology, Rosenstiel School of Marine and Atmospheric Science, University of Miami, Miami, FL, USA
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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: 3] [Impact Index Per Article: 0.8] [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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Huang PC, Liu TY, Hu MY, Casties I, Tseng YC. Energy and nitrogenous waste from glutamate/glutamine catabolism facilitates acute osmotic adjustment in non-neuroectodermal branchial cells. Sci Rep 2020; 10:9460. [PMID: 32528019 PMCID: PMC7289822 DOI: 10.1038/s41598-020-65913-1] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2018] [Accepted: 05/12/2020] [Indexed: 11/30/2022] Open
Abstract
Maintenance of homeostasis is one of the most important physiological responses for animals upon osmotic perturbations. Ionocytes of branchial epithelia are the major cell types responsible for active ion transport, which is mediated by energy-consuming ion pumps (e.g., Na+-K+-ATPase, NKA) and secondary active transporters. Consequently, in addition to osmolyte adjustments, sufficient and immediate energy replenishment is essenttableial for acclimation to osmotic changes. In this study, we propose that glutamate/glutamine catabolism and trans-epithelial transport of nitrogenous waste may aid euryhaline teleosts Japanese medaka (Oryzias latipes) during acclimation to osmotic changes. Glutamate family amino acid contents in gills were increased by hyperosmotic challenge along an acclimation period of 72 hours. This change in amino acids was accompanied by a stimulation of putative glutamate/glutamine transporters (Eaats, Sat) and synthesis enzymes (Gls, Glul) that participate in regulating glutamate/glutamine cycling in branchial epithelia during acclimation to hyperosmotic conditions. In situ hybridization of glutaminase and glutamine synthetase in combination with immunocytochemistry demonstrate a partial colocalization of olgls1a and olgls2 but not olglul with Na+/K+-ATPase-rich ionocytes. Also for the glutamate and glutamine transporters colocalization with ionocytes was found for oleaat1, oleaat3, and olslc38a4, but not oleaat2. Morpholino knock-down of Sat decreased Na+ flux from the larval epithelium, demonstrating the importance of glutamate/glutamine transport in osmotic regulation. In addition to its role as an energy substrate, glutamate deamination produces NH4+, which may contribute to osmolyte production; genes encoding components of the urea production cycle, including carbamoyl phosphate synthetase (CPS) and ornithine transcarbamylase (OTC), were upregulated under hyperosmotic challenges. Based on these findings the present work demonstrates that the glutamate/glutamine cycle and subsequent transepithelial transport of nitrogenous waste in branchial epithelia represents an essential component for the maintenance of ionic homeostasis under a hyperosmotic challenge.
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Affiliation(s)
- Pei-Chen Huang
- Marine Research Station, Institute of Cellular and organismic Biology, Academia Sinica, I-Lan County, Taiwan (ROC)
| | - Tzu-Yen Liu
- Marine Research Station, Institute of Cellular and organismic Biology, Academia Sinica, I-Lan County, Taiwan (ROC)
| | - Marian Y Hu
- Institute of Physiology, Christian-Albrechts University Kiel, Kiel, Germany
| | - Isabel Casties
- Helmholtz Centre for Ocean Research Kiel (GEOMAR), Kiel, Germany
| | - Yung-Che Tseng
- Marine Research Station, Institute of Cellular and organismic Biology, Academia Sinica, I-Lan County, Taiwan (ROC).
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13
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Liu ST, Chou MY, Wu LC, Horng JL, Lin LY. Transient receptor potential vanilloid 4 modulates ion balance through the isotocin pathway in zebrafish (Danio rerio). Am J Physiol Regul Integr Comp Physiol 2020; 318:R751-R759. [DOI: 10.1152/ajpregu.00307.2019] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Isotocin controls ion regulation through modulating the functions of ionocytes (also called mitochondria-rich cells or chloride cells). However, little is known about the upstream molecule of the isotocin system. Herein, we identify transient receptor potential vanilloid 4 (TRPV4), which regulates the mRNA and protein expressions of isotocin and affects ion regulation through the isotocin pathway. Double immunohistochemical results showed that TRPV4 is expressed in isotocinergic neurons in the hypothalamus of the adult zebrafish brain. To further elucidate the roles of TRPV4, we manipulated TRPV4 protein expression and evaluated its ionoregulatory functions in zebrafish embryos. TRPV4 gene knockdown with morpholino oligonucleotides decreased ionic contents (Na+, Cl−, and Ca2+) of whole larvae and the H+-secreting function of larval skin of zebrafish. mRNA expressions of ionocyte-related transporters, including H+-ATPase, the epithelial Ca2+ channel, and the Na+-Cl− cotransporter, were also suppressed in trpv4 morphants. Numbers of ionocytes (H+-ATPase-rich cells and Na+-K+-ATPase-rich cells) and epidermal stem cells in zebrafish larval skin also decreased after trpv4 knockdown. Our results showed that TRPV4 modulates ion balance through the isotocin pathway.
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Affiliation(s)
- Sian-Tai Liu
- Department of Life Science, National Taiwan Normal University, Taipei, Taiwan
| | - Ming-Yi Chou
- Department of Life Science, National Taiwan University, Taipei, Taiwan
| | - Liang-Chun Wu
- Department 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, Taiwan
| | - Li-Yih Lin
- Department of Life Science, National Taiwan Normal University, Taipei, Taiwan
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14
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Yen HJ, Horng JL, Yu CH, Fang CY, Yeh YH, Lin LY. Toxic effects of silver and copper nanoparticles on lateral-line hair cells of zebrafish embryos. AQUATIC TOXICOLOGY (AMSTERDAM, NETHERLANDS) 2019; 215:105273. [PMID: 31445453 DOI: 10.1016/j.aquatox.2019.105273] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/21/2019] [Revised: 08/12/2019] [Accepted: 08/13/2019] [Indexed: 06/10/2023]
Abstract
The potential toxicity of nanoparticles (NPs) to the early stages of fish is still unclear. In this study, we investigated the toxic effects of silver (AgNPs) and copper nanoparticles (CuNPs) on lateral-line hair cells of zebrafish embryos. Zebrafish embryos were incubated in different concentrations of AgNPs and CuNPs at 0˜96 h post-fertilization (hpf). Both AgNPs and CuNPs were found to cause toxic effects in zebrafish embryos in a dose-dependent manner. Values of the 96-h 50% lethal concentration (LC50) of AgNPs and CuNPs were 6.1 ppm (56.5 μM) and 2.61 ppm (41.1 μM), respectively. The number of FM1-43-labeled hair cells and the microstructure of hair bundles were significantly impaired by AgNPs [≥1 ppm (9.3 μM)] and CuNPs [≥0.01 ppm (0.16 μM)]. Ca2+ influxes at hair bundles of hair cells were measured with a scanning ion-selective microelectrode technique to evaluate the function of hair cells. AgNPs [≥0.1 ppm (0.9 μM)] and CuNPs [≥0.01 ppm (0.16 μM)] were both found to significantly reduce Ca2+ influxes. Similar toxic effects were also found in hatched embryos subjected to 4 h of exposure (96˜100 hpf) to AgNPs and CuNPs. This study revealed that lateral-line hair cells of zebrafish are susceptible to AgNPs and CuNPs, and these contaminants in aquatic environments could pose a threat to fish survival.
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Affiliation(s)
- Hsiu-Ju Yen
- 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, National Yang-Ming University, School of Medicine, Faculty of Medicine, Taipei, Taiwan
| | - Jiun-Lin Horng
- Department of Anatomy and Cell Biology, School of Medicine, College of Medicine, Taipei Medical University, Taipei, Taiwan
| | - Ching-Hua Yu
- Department of Life Science, School of Life Science, National Taiwan Normal University, Taipei, Taiwan
| | - Ching-Ya Fang
- Department of Life Science, School of Life Science, National Taiwan Normal University, Taipei, Taiwan
| | - Ya-Hsin Yeh
- Department of Anatomy and Cell Biology, School of Medicine, College of Medicine, Taipei Medical University, Taipei, Taiwan
| | - Li-Yih Lin
- Department of Life Science, School of Life Science, National Taiwan Normal University, Taipei, Taiwan.
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15
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Xiao J, Li QY, Tu JP, Chen XL, Chen XH, Liu QY, Liu H, Zhou XY, Zhao YZ, Wang HL. Stress response and tolerance mechanisms of ammonia exposure based on transcriptomics and metabolomics in Litopenaeus vannamei. ECOTOXICOLOGY AND ENVIRONMENTAL SAFETY 2019; 180:491-500. [PMID: 31121556 DOI: 10.1016/j.ecoenv.2019.05.029] [Citation(s) in RCA: 45] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/26/2019] [Revised: 05/06/2019] [Accepted: 05/10/2019] [Indexed: 06/09/2023]
Abstract
Ammonia, one of the major limiting environment factors in aquaculture, may pose a threat to the shrimp growth, reproduction and survival. In this study, to understand molecular differences of transcriptomic and metabolomic responses and investigate the tolerance mechanisms underlying ammonia stress in Litopenaeus vannamei, ammonia-tolerant family (LV-AT) and ammonia-sensitive family (LV-AS) of these two extreme families were exposed to high-concentration (NH4Cl, 46 mg/L) ammonia for 24 h. The comparative transcriptome analysis between ammonia-treated and control (LV-C) groups revealed involvement of immune defense, cytoskeleton remodeling, antioxidative system and metabolic pathway in ammonia-stress response of L. vannamei. Likewise, metabolomics analysis showed that ammonia exposure could disturb amino acid metabolism, nucleotide metabolism and lipid metabolism, with metabolism related-genes changed according to RNA-seq analysis. The comparison of metabolite and transcript profiles between LV-AT and LV-AS indicated that LV-AT used the enhanced glycolysis and tricarboxylic acid (TCA) cycle strategies for energy supply and ammonia excretion to adapt high-concentration ammonia. Furthermore, some of genes involved in the detoxification and ammonia excretion were highly expressed in LV-AT. We speculate that the higher ability of ammonia excretion and detoxification and the accelerated energy metabolism for energy supplies might be the adaptive strategies for LV-AT relative to LV-AS after ammonia stress. Collectively, the combination of transcriptomics and metabolomics results will greatly contribute to incrementally understand the stress responses on ammonia exposure to L. vannamei and supply molecular level support for evaluating the environmental effects of ammonia on aquatic organisms. The results further constitute new sights on the potential molecular mechanisms of ammonia adaptive strategies in shrimps at the transcriptomics and metabolomics levels.
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Affiliation(s)
- Jie Xiao
- Key Lab of Freshwater Animal Breeding, Key Laboratory of Agricultural Animal Genetics, Breeding and Reproduction, Ministry of Education, College of Fishery Huazhong Agricultural University, Wuhan, PR China
| | - Qiang-Yong Li
- Guangxi Academy of Fishery Sciences, Guangxi Key Laboratory of Aquatic Genetic Breeding and Healthy Aquaculture, Guangxi, Nanning, 530021, China, PR China
| | - Jia-Peng Tu
- Key Lab of Freshwater Animal Breeding, Key Laboratory of Agricultural Animal Genetics, Breeding and Reproduction, Ministry of Education, College of Fishery Huazhong Agricultural University, Wuhan, PR China
| | - Xiu-Li Chen
- Guangxi Academy of Fishery Sciences, Guangxi Key Laboratory of Aquatic Genetic Breeding and Healthy Aquaculture, Guangxi, Nanning, 530021, China, PR China
| | - Xiao-Han Chen
- Guangxi Academy of Fishery Sciences, Guangxi Key Laboratory of Aquatic Genetic Breeding and Healthy Aquaculture, Guangxi, Nanning, 530021, China, PR China
| | - Qing-Yun Liu
- Guangxi Academy of Fishery Sciences, Guangxi Key Laboratory of Aquatic Genetic Breeding and Healthy Aquaculture, Guangxi, Nanning, 530021, China, PR China
| | - Hong Liu
- Key Lab of Freshwater Animal Breeding, Key Laboratory of Agricultural Animal Genetics, Breeding and Reproduction, Ministry of Education, College of Fishery Huazhong Agricultural University, Wuhan, PR China
| | - Xiao-Yun Zhou
- Key Lab of Freshwater Animal Breeding, Key Laboratory of Agricultural Animal Genetics, Breeding and Reproduction, Ministry of Education, College of Fishery Huazhong Agricultural University, Wuhan, PR China
| | - Yong-Zhen Zhao
- Guangxi Academy of Fishery Sciences, Guangxi Key Laboratory of Aquatic Genetic Breeding and Healthy Aquaculture, Guangxi, Nanning, 530021, China, PR China.
| | - Huan-Ling Wang
- Key Lab of Freshwater Animal Breeding, Key Laboratory of Agricultural Animal Genetics, Breeding and Reproduction, Ministry of Education, College of Fishery Huazhong Agricultural University, Wuhan, PR China.
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16
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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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17
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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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18
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Chen XL, Zhang B, Chng YR, Ong JLY, Chew SF, Wong WP, Lam SH, Ip YK. Na +/H + Exchanger 3 Is Expressed in Two Distinct Types of Ionocyte, and Probably Augments Ammonia Excretion in One of Them, in the Gills of the Climbing Perch Exposed to Seawater. Front Physiol 2017; 8:880. [PMID: 29209224 PMCID: PMC5701670 DOI: 10.3389/fphys.2017.00880] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2017] [Accepted: 10/18/2017] [Indexed: 01/22/2023] Open
Abstract
The freshwater climbing perch, Anabas testudineus, is an euryhaline teleost and an obligate air-breather with the ability to actively excrete ammonia. Members of the Na+/H+ exchanger (NHE) family help maintain intracellular pH homeostasis and ionic balance through the electroneutral exchange of Na+ and H+. This study aimed to obtain, from the gills of A. testudineus, the full cDNA coding sequence of nhe3, and to determine the effects of exposure to seawater or 100 mmol l-1 of NH4Cl in fresh water on its mRNA and protein expression levels. Efforts were also made to elucidate the type of ionocyte that Nhe3 was associated with in the branchial epithelium of A. testudineus. The transcript level and protein abundance of nhe3/Nhe3 were very low in the gills of freshwater A. testudineus, but they increased significantly in the gills of fish acclimated to seawater. In the gills of fish exposed to seawater, Nhe3 was expressed in two distinct types of seawater-inducible Na+/K+-ATPase (Nka)-immunoreactive ionocytes. In Nkaα1b-immunoreactive ionocytes, Nhe3 had an apical localization. As these ionocytes also expressed apical Rhcg1 and basolateral Rhcg2, which are known to transport ammonia, they probably participated in proton-facilitated ammonia excretion in A. testudineus during seawater acclimation. In Nkaα1c-immunoreactive ionocytes, Nhe3 was atypically expressed in the basolateral membrane, and its physiological function is uncertain. For A. testudineus exposed to NH4Cl in fresh water, the transcript and protein expression levels of nhe3/Nhe3 remained low. In conclusion, the branchial Nhe3 of A. testudineus plays a greater physiological role in passive ammonia transport and acid-base balance during seawater acclimation than in active ammonia excretion during environmental ammonia exposure.
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Affiliation(s)
- Xiu L. Chen
- Department of Biological Sciences, National University of Singapore, Singapore, Singapore
| | - Biyan Zhang
- Department of Biological Sciences, National University of Singapore, Singapore, Singapore
| | - You R. Chng
- Department of Biological Sciences, National University of Singapore, Singapore, Singapore
| | - Jasmine L. Y. Ong
- Department of Biological Sciences, National University of Singapore, Singapore, Singapore
| | - Shit F. Chew
- Natural Sciences and Science Education, National Institute of Education, Nanyang Technological University, Singapore, Singapore
| | - Wai P. Wong
- Department of Biological Sciences, National University of Singapore, Singapore, Singapore
| | - Siew H. Lam
- Department of Biological Sciences, National University of Singapore, Singapore, Singapore
- NUS Environmental Research Institute, National University of Singapore, Singapore, Singapore
| | - Yuen K. Ip
- Department of Biological Sciences, National University of Singapore, Singapore, Singapore
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19
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Esbaugh AJ. Physiological implications of ocean acidification for marine fish: emerging patterns and new insights. J Comp Physiol B 2017; 188:1-13. [PMID: 28547292 DOI: 10.1007/s00360-017-1105-6] [Citation(s) in RCA: 50] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2017] [Revised: 05/04/2017] [Accepted: 05/10/2017] [Indexed: 12/15/2022]
Abstract
Ocean acidification (OA) is an impending environmental stress facing all marine life, and as such has been a topic of intense research interest in recent years. Numerous detrimental effects have been documented in marine fish, ranging from reduced mortality to neurosensory impairment, and the prevailing opinions state that these effects are largely the downstream consequences of altered blood carbon dioxide chemistry caused by respiratory acid-base disturbances. While the respiratory acid-base disturbances are consistent responses to OA across tested fish species, it is becoming increasingly clear that there is wide variability in the degree of downstream impairments between species. This can also be extended to intraspecies variability, whereby some individuals have tolerant physiological traits, while others succumb to the effects of OA. This review will synthesize relevant literature on marine fish to highlight consistent trends of impairment, as well as observed interspecies variability in the responses to OA, and the potential routes of physiological acclimation. In all cases, whole animal responses are linked to demonstrated or proposed physiological impairments. Major topics of focus include: (1) respiratory acid-base disturbances; (2) early life survival and growth; (3) the implications for metabolic performance, activity, and reproduction; and (4) emerging physiological theories pertaining to neurosensory impairment and the role of GABAA receptors. Particular emphasis is placed on the importance of understanding the underlying physiological traits that confer inter- and intraspecies tolerance, as the abundance of these traits will decide the long-term outlook of marine fish.
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Affiliation(s)
- Andrew J Esbaugh
- Marine Science Institute, University of Texas at Austin, Austin, TX, 78373, USA.
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20
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Inokuchi M, Nakamura M, Miyanishi H, Hiroi J, Kaneko T. Functional classification of gill ionocytes and spatiotemporal changes in their distribution after transfer from seawater to fresh water in Japanese seabass. J Exp Biol 2017; 220:4720-4732. [DOI: 10.1242/jeb.167320] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2017] [Accepted: 10/24/2017] [Indexed: 01/26/2023]
Abstract
Spatiotemporal changes in branchial ionocyte distribution were investigated following transfer from seawater (SW) to fresh water (FW) in Japanese seabass. The mRNA expression levels of cystic fibrosis transmembrane conductance regulator (CFTR) and Na+/K+/2Cl− cotransporter 1a (NKCC1a) in the gills rapidly decreased after transfer to FW, whereas Na+/H+ exchanger 3 (NHE3) and Na+/Cl− cotransporter 2 (NCC2) expressions were upregulated following the transfer. By quadruple-color whole-mount immunofluorescence staining with anti-Na+/K+-ATPase, anti-NHE3, anti-CFTR and T4 (anti-NKCC1a/NCC2) antibodies, we classified ionocytes into one SW-type and two FW-types; NHE3 cell and NCC2 cell. Time-course observation after transfer revealed an intermediate type between SW-type and FW-type NHE3 ionocytes, suggesting functional plasticity of ionocytes. Finally, on the basis of the ionocyte classification of Japanese seabass, we observed the location of ionocyte subtypes on frozen sections of the gill filaments stained by triple-color immunofluorescence staining. Our observation indicated that SW-type ionocytes transformed into FW-type NHE3 ionocytes and at the same time shifted their distribution from filaments to lamellae. On the other hand, FW-specific NCC2 ionocytes appeared mainly in the filaments. Taken together, these findings indicated that ionocytes originated from undifferentiated cells in the filaments and expanded their distribution to the lamellae during FW acclimation.
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Affiliation(s)
- Mayu Inokuchi
- Department of Life Sciences, Toyo University, Itakura, Gunma 374-0193, Japan
| | - Masahiro Nakamura
- National Research Institute of Fisheries and Environment of Inland Sea, Fisheries Research Agency, Imabari, Ehime 794-2305, Japan
| | - Hiroshi Miyanishi
- Faculty of Agriculture, University of Miyazaki, Gakuen-kibanadai-nishi, Miyazaki 889-2192, Japan
| | - Junya Hiroi
- Department of Anatomy, St. Marianna University School of Medicine, Kawasaki, Kanagawa 216-8511, Japan
| | - Toyoji Kaneko
- Department of Aquatic Bioscience, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Bunkyo, Tokyo 113-8657, Japan
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21
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Liu ST, Horng JL, Chen PY, Hwang PP, Lin LY. Salt secretion is linked to acid-base regulation of ionocytes in seawater-acclimated medaka: new insights into the salt-secreting mechanism. Sci Rep 2016; 6:31433. [PMID: 27511107 PMCID: PMC4980601 DOI: 10.1038/srep31433] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2015] [Accepted: 07/12/2016] [Indexed: 11/25/2022] Open
Abstract
Ionocytes in the skin and gills of seawater (SW) teleosts are responsible for both salt and acid secretion. However, the mechanism through which ionocytes secrete acid is still unclear. Here, we hypothesized that apical Na+/H+ exchangers (NHE2/3), carbonic anhydrase (CA2-like), and basolateral HCO3−/Cl− exchanger (AE1) are involved in acid secretion. In addition, the hypothesized involvement of basolateral AE1 suggested that acid secretion may be linked to Cl− secretion by ionocytes. The scanning ion-selective electrode technique (SIET) was used to measure H+ and Cl− secretion by ionocytes in the skin of medaka larvae acclimated to SW. Treatment with inhibitors of NHE, CA, and AE suppressed both H+ and Cl− secretion by ionocytes. Short-term exposure to hypercapnic SW stimulated both H+ and Cl− secretion. mRNA of CA2-like and AE1 were localized to ionocytes in the skin. Branchial mRNA levels of NKCC1a, CA2-like, and AE1a increased together with the salinity to which fish were acclimated. In addition, both AE1a and AE1b mRNA increased in fish acclimated to acidified (pH 7) SW; NKCC1a mRNA increased in fish acclimated to pH 9 SW. This study reveals the mechanism of H+ secretion by ionocytes, and refines our understanding of the well-established mechanism of Cl− secretion by ionocytes of SW fish.
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Affiliation(s)
- Sian-Tai Liu
- Department of Life Science, National Taiwan Normal University, Taipei, Taiwan
| | - Jiun-Lin Horng
- Department of Anatomy and Cell Biology, Taipei Medical University, Taipei, Taiwan
| | - Po-Yen Chen
- Department of Life Science, National Taiwan Normal University, Taipei, Taiwan
| | - Pung-Pung Hwang
- Institute of Cellular and Organismic Biology, Academia Sinica, Taipei, Taiwan
| | - Li-Yih Lin
- Department of Life Science, National Taiwan Normal University, Taipei, Taiwan
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22
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Hu MY, Hwang PP, Tseng YC. Recent advances in understanding trans-epithelial acid-base regulation and excretion mechanisms in cephalopods. Tissue Barriers 2015; 3:e1064196. [PMID: 26716070 DOI: 10.1080/21688370.2015.1064196] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2015] [Revised: 06/09/2015] [Accepted: 06/15/2015] [Indexed: 01/17/2023] Open
Abstract
Cephalopods have evolved complex sensory systems and an active lifestyle to compete with fish for similar resources in the marine environment. Their highly active lifestyle and their extensive protein metabolism has led to substantial acid-base regulatory abilities enabling these organisms to cope with CO2 induced acid-base disturbances. In convergence to teleost, cephalopods possess an ontogeny-dependent shift in ion-regulatory epithelia with epidermal ionocytes being the major site of embryonic acid-base regulation and ammonia excretion, while gill epithelia take these functions in adults. Although the basic morphology and excretory function of gill epithelia in cephalopods were outlined almost half a century ago, modern immunohistological and molecular techniques are bringing new insights to the mechanistic basis of acid-base regulation and excretion of nitrogenous waste products (e.g. NH3/NH4 (+)) across ion regulatory epithelia of cephalopods. Using cephalopods as an invertebrate model, recent findings reveal partly conserved mechanisms but also novel aspects of acid-base regulation and nitrogen excretion in these exclusively marine animals. Comparative studies using a range of marine invertebrates will create a novel and exciting research direction addressing the evolution of pH regulatory and excretory systems.
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Affiliation(s)
- Marian Y Hu
- Institute of Physiology; Christian-Albrechts University Kiel ; Kiel, Germany ; Institute of Cellular and Organismic Biology; Academia Sinica ; Taipei City, Taiwan
| | - Pung-Pung Hwang
- Institute of Cellular and Organismic Biology; Academia Sinica ; Taipei City, Taiwan
| | - Yung-Che Tseng
- Department of Life Science; National Taiwan Normal University ; Taipei City, Taiwan
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23
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Lin CH, Shih TH, Liu ST, Hsu HH, Hwang PP. Cortisol Regulates Acid Secretion of H(+)-ATPase-rich Ionocytes in Zebrafish (Danio rerio) Embryos. Front Physiol 2015; 6:328. [PMID: 26635615 PMCID: PMC4646979 DOI: 10.3389/fphys.2015.00328] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2015] [Accepted: 10/29/2015] [Indexed: 01/01/2023] Open
Abstract
Systemic acid-base regulation is vital for physiological processes in vertebrates. Freshwater (FW) fish live in an inconstant environment, and thus frequently face ambient acid stress. FW fish have to efficiently modulate their acid secretion processes for body fluid acid-base homeostasis during ambient acid challenge; hormonal control plays an important role in such physiological regulation. The hormone cortisol was previously proposed to be associated with acid base regulation in FW fish; however, the underlying mechanism has not been fully described. In the present study, mRNA expression of acid-secreting related transporters and cyp11b (encoding an enzyme involved in cortisol synthesis) in zebrafish embryos was stimulated by treatment with acidic FW (AFW, pH 4.0) for 3 d. Exogenous cortisol treatment (20 mg/L, 3 d) resulted in upregulated expression of transporters related to acid secretion and increased acid secretion function at the organism level in zebrafish embryos. Moreover, cortisol treatment also significantly increased the acid secretion capacity of H(+)-ATPase-rich cells (HRCs) at the cellular level. In loss-of-function experiments, microinjection of glucocorticoid receptor (GR) morpholino (MO) suppressed the expression of acid-secreting related transporters, and decreased acid secretion function at both the organism and cellular levels; on the other hand, mineralocorticoid receptor (MR) MO did not induce any effects. Such evidence supports the hypothesized role of cortisol in fish acid-base regulation, and provides new insights into the roles of cortisol; cortisol-GR signaling stimulates zebrafish acid secretion function through transcriptional/translational regulation of the transporters and upregulation of acid secretion capacity in each acid-secreting ionocyte.
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Affiliation(s)
- Chia-Hao Lin
- Institute of Cellular and Organismic Biology, Academia SinicaTaipei, Taiwan
- National Institute for Basic Biology, National Institutes of Natural SciencesOkazaki, Japan
| | - Tin-Han Shih
- Biodiversity Research Center, Academia SinicaTaipei, Taiwan
| | - Sian-Tai Liu
- Department of Life Science, National Taiwan Normal UniversityTaipei, Taiwan
| | - Hao-Hsuan Hsu
- Institute of Cellular and Organismic Biology, Academia SinicaTaipei, Taiwan
| | - Pung-Pung Hwang
- Institute of Cellular and Organismic Biology, Academia SinicaTaipei, Taiwan
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24
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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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A new model for fish ion regulation: identification of ionocytes in freshwater- and seawater-acclimated medaka (Oryzias latipes). Cell Tissue Res 2014; 357:225-43. [PMID: 24842048 DOI: 10.1007/s00441-014-1883-z] [Citation(s) in RCA: 71] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2013] [Accepted: 03/27/2014] [Indexed: 10/25/2022]
Abstract
The ion regulation mechanisms of fishes have been recently studied in zebrafish (Danio rerio), a stenohaline species. However, recent advances using this organism are not necessarily applicable to euryhaline fishes. The euryhaline species medaka (Oryzias latipes), which, like zebrafish, is genetically well categorized and amenable to molecular manipulation, was proposed as an alternative model for studying osmoregulation during acclimation to different salinities. To establish its suitability as an alternative, the present study was conducted to (1) identify different types of ionocytes in the embryonic skin and (2) analyze gene expressions of the transporters during seawater acclimation. Double/triple in situ hybridization and/or immunocytochemistry revealed that freshwater (FW) medaka contain three types of ionocyte: (1) Na(+)/H(+) exchanger 3 (NHE3) cells with apical NHE3 and basolateral Na(+)-K(+)-2Cl(-) cotransporter (NKCC), Na(+)-K(+)-ATPase (NKA) and anion exchanger (AE); (2) Na(+)-Cl(-) cotransporter (NCC) cells with apical NCC and basolateral H(+)-ATPase; and (3) epithelial Ca(2+) channel (ECaC) cells [presumed accessory (AC) cells] with apical ECaC. On the other hand, seawater (SW) medaka has a single predominant ionocyte type, which possesses apical cystic fibrosis transmembrane conductance regulator (CFTR) and NHE3 and basolateral NKCC and NKA and is accompanied by smaller AC cells that express lower levels of basolateral NKA. Reciprocal gene expressions of decreased NHE3, AE, NCC and ECaC and increased CFTR and NKCC in medaka gills during SW were revealed by quantative PCR analysis.
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Esophageal desalination is mediated by Na⁺, H⁺ exchanger-2 in the gulf toadfish (Opsanus beta). Comp Biochem Physiol A Mol Integr Physiol 2014; 171:57-63. [PMID: 24548910 DOI: 10.1016/j.cbpa.2014.02.012] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2013] [Revised: 01/30/2014] [Accepted: 02/11/2014] [Indexed: 10/25/2022]
Abstract
Esophageal desalination is a crucial step in the gastrointestinal water absorption pathway, as this pre-intestinal processing establishes the osmotic conditions necessary for water absorption. Previous work has shown that esophageal Na(+) absorption is amiloride sensitive; however, it is as yet unclear if Na(+), H(+) exchangers (NHE) or Na(+) channels (ENaC) are responsible. The purpose of the current study was therefore to investigate the roles that NHE isoforms may play in this process in a marine teleost, the gulf toadfish (Opsanus beta), as well as what role NHE isoforms may play in the downstream intestinal Na(+) transport. A combination of symmetrical current clamp and asymmetrical voltage clamp experiments showed the esophagus to contain both an ion absorptive current (I(sc)=0.83±0.68) and serosal side negative transepithelial potential (TEP=-4.9±0.6). (22)Na uptake (J(Na)(m→s)) was inhibited by 0.5 mM EIPA, with no effect of 0.1 mM amiloride, 1 mM furosemide or 1 mM thiazide. A Cl(-) free saline reduced J(Na)(m→s) by 40% while also reducing conductance and reversing TEP. These results suggest that both transcellular and paracellular components contribute to esophageal Na(+) transport, with transcellular transport mediated by NHE. The NHE1, NHE2 and NHE3 genes were amplified and tissue distribution analysis by real-time PCR showed high NHE2 expression levels in the esophagus and stomach. Little NHE3 expression was observed throughout the gastrointestinal tract, and NHE2 expression was absent from the intestine. Hypersalinity (60 ppt) had no effect on the expression profile of NHE2, slc4a2, scl26a6, CAc or V-type ATPase (β-subunit), suggesting that esophageal desalination is less flexible in response to osmotic stress than the intestine.
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