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Takvam M, Wood CM, Kryvi H, Nilsen TO. Role of the kidneys in acid-base regulation and ammonia excretion in freshwater and seawater fish: implications for nephrocalcinosis. Front Physiol 2023; 14:1226068. [PMID: 37457024 PMCID: PMC10339814 DOI: 10.3389/fphys.2023.1226068] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2023] [Accepted: 06/12/2023] [Indexed: 07/18/2023] Open
Abstract
Maintaining normal pH levels in the body fluids is essential for homeostasis and represents one of the most tightly regulated physiological processes among vertebrates. Fish are generally ammoniotelic and inhabit diverse aquatic environments that present many respiratory, acidifying, alkalinizing, ionic and osmotic stressors to which they are able to adapt. They have evolved flexible strategies for the regulation of acid-base equivalents (H+, NH4 +, OH- and HCO3 -), ammonia and phosphate to cope with these stressors. The gills are the main regulatory organ, while the kidneys play an important, often overlooked accessory role in acid-base regulation. Here we outline the kidneys role in regulation of acid-base equivalents and two of the key 'urinary buffers', ammonia and phosphate, by integrating known aspects of renal physiology with recent advances in the molecular and cellular physiology of membrane transport systems in the teleost kidneys. The renal transporters (NHE3, NBC1, AE1, SLC26A6) and enzymes (V-type H+ATPase, CAc, CA IV, ammoniagenic enzymes) involved in H+ secretion, bicarbonate reabsorption, and the net excretion of acidic and basic equivalents, ammonia, and inorganic phosphate are addressed. The role of sodium-phosphate cotransporter (Slc34a2b) and rhesus (Rh) glycoproteins (ammonia channels) in conjunction with apical V-type H+ ATPase and NHE3 exchangers in these processes are also explored. Nephrocalcinosis is an inflammation-like disorder due to the precipitation of calcareous material in the kidneys, and is listed as one of the most prevalent pathologies in land-based production of salmonids in recirculating aquaculture systems. The causative links underlying the pathogenesis and etiology of nephrocalcinosis in teleosts is speculative at best, but acid-base perturbation is probably a central pathophysiological cause. Relevant risk factors associated with nephrocalcinosis are hypercapnia and hyperoxia in the culture water. These raise internal CO2 levels in the fish, triggering complex branchial and renal acid-base compensations which may promote formation of kidney stones. However, increased salt loads through the rearing water and the feed may increase the prevalence of nephrocalcinosis. An increased understanding of the kidneys role in acid-base and ion regulation and how this relates to renal diseases such as nephrocalcinosis will have applied relevance for the biologist and aquaculturist alike.
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Affiliation(s)
- Marius Takvam
- Department of Biological Sciences, University of Bergen, Bergen, Norway
| | - Chris M. Wood
- Department of Zoology, University of British Columbia, Vancouver, BC, Canada
| | - H. Kryvi
- Department of Biological Sciences, University of Bergen, Bergen, Norway
| | - Tom O. Nilsen
- Department of Biological Sciences, University of Bergen, Bergen, Norway
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2
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Fehsenfeld S, Quijada-Rodriguez AR, Zhouyao H, Durant AC, Donini A, Sachs M, Eck P, Weihrauch D. Hiat1 as a new transporter involved in ammonia regulation. Sci Rep 2023; 13:4416. [PMID: 36932112 PMCID: PMC10023664 DOI: 10.1038/s41598-023-31503-0] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2022] [Accepted: 03/13/2023] [Indexed: 03/19/2023] Open
Abstract
The orphan transporter hippocampus-abundant transcript 1 (Hiat1) was first identified in the mammalian brain. Its specific substrate specificity, however, has not been investigated to date. Here, we identified and analyzed Hiat1 in a crustacean, the green crab Carcinus maenas. Our phylogenetic analysis showed that Hiat1 protein is conserved at a considerable level between mammals and this invertebrate (ca. 78% identical and conserved amino acids). Functional expression of Carcinus maenas Hiat1 in Xenopus laevis oocytes demonstrated the capability to transport ammonia (likely NH4+) in a sodium-dependent manner. Furthermore, applying quantitative polymerase chain reaction, our results indicated a physiological role for Carcinus maenas Hiat1 in ammonia homeostasis, as mRNA abundance increased in posterior gills in response to elevated circulating hemolymph ammonia upon exposure to high environmental ammonia. Its ubiquitous mRNA expression pattern also suggests an essential role in general cellular detoxification of ammonia. Overall, our results introduce a new ubiquitously expressed ammonia transporter, consequently demanding revision of our understanding of ammonia handling in key model systems from mammalian kidneys to crustacean and fish gills.
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Affiliation(s)
- Sandra Fehsenfeld
- Département de Biologie, Chimie et Géographie, Université du Quebec à Rimouski, 300 Allée des Ursulines, Rimouski, QC, G5L 3A1, Canada.
- Department of Biological Sciences, University of Manitoba, 50 Sifton Road, Winnipeg, MB, R3T 2N2, Canada.
| | - Alex R Quijada-Rodriguez
- Department of Biological Sciences, University of Manitoba, 50 Sifton Road, Winnipeg, MB, R3T 2N2, Canada
| | - Haonan Zhouyao
- Department of Food and Human Nutritional Sciences, University of Manitoba, 35 Chancellor's Circle, Winnipeg, MB, R3T 2N2, Canada
| | - Andrea C Durant
- Department of Biology, York University, 4700 Keele St, Toronto, ON, M3J 1P3, Canada
- Department of Biological Sciences, University of Toronto Scarborough, 1265 Military Trail, Toronto, ON, M1C 1A4, Canada
| | - Andrew Donini
- Department of Biology, York University, 4700 Keele St, Toronto, ON, M3J 1P3, Canada
| | - Maria Sachs
- Department of Biological Sciences, University of Manitoba, 50 Sifton Road, Winnipeg, MB, R3T 2N2, Canada
| | - Peter Eck
- Department of Food and Human Nutritional Sciences, University of Manitoba, 35 Chancellor's Circle, Winnipeg, MB, R3T 2N2, Canada
| | - Dirk Weihrauch
- Department of Biological Sciences, University of Manitoba, 50 Sifton Road, Winnipeg, MB, R3T 2N2, Canada
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3
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Zhang R, Zhao Z, Li M, Luo L, Wang S, Guo K, Xu W. Metabolomics analysis reveals the response mechanism to carbonate alkalinity toxicity in the gills of Eriocheir sinensis. Comp Biochem Physiol C Toxicol Pharmacol 2023; 263:109487. [PMID: 36244570 DOI: 10.1016/j.cbpc.2022.109487] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/30/2022] [Revised: 09/21/2022] [Accepted: 10/09/2022] [Indexed: 11/19/2022]
Abstract
Aquatic water with carbonate alkalinity presents a survival challenge to aquatic animals. As an economically important crab, large quantities of Eriocheir sinensis are cultured in carbonate-type saline-alkali ponds, while the toxic effect on E. sinensis from carbonate alkalinity is still unclear. In this study, untargeted liquid chromatography-mass spectrometry metabolomics was performed to investigate the metabolic change caused by culture alkalinity, and confirmed distinct physiological response under gradient alkalinities. There were 39 differential metabolites obtained in the low-alkalinity group (4.35 mmol/L) versus control group, and "arachidonic acid metabolism" was enriched as a core response pathway. 93 differential metabolites were identified in the high-alkalinity group (17.43 mmol/L) versus control group, and a complex response net was manifested through integrated analysis, building by "steroid hormone biosynthesis", "phenylalanine, tyrosine and tryptophan biosynthesis", "phosphonate and phosphinate metabolism", "phenylalanine metabolism", "mineral absorption", "purine metabolism" and "carbon metabolism". This indicated the mobilization of energy reserves and the suppression of protein and amino acid catabolism were manifested in E. sinensis gills to defense high alkalinity stress. In addition, the persistently regulation of key metabolites under various alkalinity, including diuretic compound "spironolactone" and the antiphlogistic compound "LXB4", suggested anti-inflammatory action and excretion regulation were initiated to defend the stress.
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Affiliation(s)
- Rui Zhang
- Key Open Laboratory of Cold Water Fish Germplasm Resources and Breeding of Heilongjiang Province, Heilongjiang River Fisheries Research Institute, Chinese Academy of Fishery Sciences, Harbin 150070, People's Republic of China; Engineering Technology Research Center of Saline-alkaline Water Fisheries (Harbin), Chinese Academy of Fishery Sciences, Harbin 150070, People's Republic of China
| | - Zhigang Zhao
- Key Open Laboratory of Cold Water Fish Germplasm Resources and Breeding of Heilongjiang Province, Heilongjiang River Fisheries Research Institute, Chinese Academy of Fishery Sciences, Harbin 150070, People's Republic of China; Engineering Technology Research Center of Saline-alkaline Water Fisheries (Harbin), Chinese Academy of Fishery Sciences, Harbin 150070, People's Republic of China.
| | - Mingshuai Li
- Key Open Laboratory of Cold Water Fish Germplasm Resources and Breeding of Heilongjiang Province, Heilongjiang River Fisheries Research Institute, Chinese Academy of Fishery Sciences, Harbin 150070, People's Republic of China; College of Animal Science and Technology, Northeast Agricultural University, Harbin 150030, People's Republic of China
| | - Liang Luo
- Key Open Laboratory of Cold Water Fish Germplasm Resources and Breeding of Heilongjiang Province, Heilongjiang River Fisheries Research Institute, Chinese Academy of Fishery Sciences, Harbin 150070, People's Republic of China; Engineering Technology Research Center of Saline-alkaline Water Fisheries (Harbin), Chinese Academy of Fishery Sciences, Harbin 150070, People's Republic of China
| | - Shihui Wang
- Key Open Laboratory of Cold Water Fish Germplasm Resources and Breeding of Heilongjiang Province, Heilongjiang River Fisheries Research Institute, Chinese Academy of Fishery Sciences, Harbin 150070, People's Republic of China; Engineering Technology Research Center of Saline-alkaline Water Fisheries (Harbin), Chinese Academy of Fishery Sciences, Harbin 150070, People's Republic of China
| | - Kun Guo
- Key Open Laboratory of Cold Water Fish Germplasm Resources and Breeding of Heilongjiang Province, Heilongjiang River Fisheries Research Institute, Chinese Academy of Fishery Sciences, Harbin 150070, People's Republic of China; Engineering Technology Research Center of Saline-alkaline Water Fisheries (Harbin), Chinese Academy of Fishery Sciences, Harbin 150070, People's Republic of China
| | - Wei Xu
- Key Open Laboratory of Cold Water Fish Germplasm Resources and Breeding of Heilongjiang Province, Heilongjiang River Fisheries Research Institute, Chinese Academy of Fishery Sciences, Harbin 150070, People's Republic of China; Engineering Technology Research Center of Saline-alkaline Water Fisheries (Harbin), Chinese Academy of Fishery Sciences, Harbin 150070, People's Republic of China
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4
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Takvam M, Wood CM, Kryvi H, Nilsen TO. Ion Transporters and Osmoregulation in the Kidney of Teleost Fishes as a Function of Salinity. Front Physiol 2021; 12:664588. [PMID: 33967835 PMCID: PMC8098666 DOI: 10.3389/fphys.2021.664588] [Citation(s) in RCA: 40] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2021] [Accepted: 03/24/2021] [Indexed: 12/13/2022] Open
Abstract
Euryhaline teleosts exhibit major changes in renal function as they move between freshwater (FW) and seawater (SW) environments, thus tolerating large fluctuations in salinity. In FW, the kidney excretes large volumes of water through high glomerular filtration rates (GFR) and low tubular reabsorption rates, while actively reabsorbing most ions at high rates. The excreted product has a high urine flow rate (UFR) with a dilute composition. In SW, GFR is greatly reduced, and the tubules reabsorb as much water as possible, while actively secreting divalent ions. The excreted product has a low UFR, and is almost isosmotic to the blood plasma, with Mg2+, SO42–, and Cl– as the major ionic components. Early studies at the organismal level have described these basic patterns, while in the last two decades, studies of regulation at the cell and molecular level have been implemented, though only in a few euryhaline groups (salmonids, eels, tilapias, and fugus). There have been few studies combining the two approaches. The aim of the review is to integrate known aspects of renal physiology (reabsorption and secretion) with more recent advances in molecular water and solute physiology (gene and protein function of transporters). The renal transporters addressed include the subunits of the Na+, K+- ATPase (NKA) enzyme, monovalent ion transporters for Na+, Cl–, and K+ (NKCC1, NKCC2, CLC-K, NCC, ROMK2), water transport pathways [aquaporins (AQP), claudins (CLDN)], and divalent ion transporters for SO42–, Mg2+, and Ca2+ (SLC26A6, SLC26A1, SLC13A1, SLC41A1, CNNM2, CNNM3, NCX1, NCX2, PMCA). For each transport category, we address the current understanding at the molecular level, try to synthesize it with classical knowledge of overall renal function, and highlight knowledge gaps. Future research on the kidney of euryhaline fishes should focus on integrating changes in kidney reabsorption and secretion of ions with changes in transporter function at the cellular and molecular level (gene and protein verification) in different regions of the nephrons. An increased focus on the kidney individually and its functional integration with the other osmoregulatory organs (gills, skin and intestine) in maintaining overall homeostasis will have applied relevance for aquaculture.
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Affiliation(s)
- Marius Takvam
- Department of Biological Sciences, University of Bergen, Bergen, Norway.,NORCE, Norwegian Research Centre, NORCE Environment, Bergen, Norway
| | - Chris M Wood
- Department of Zoology, University of British Columbia, Vancouver, BC, Canada
| | - Harald Kryvi
- Department of Biological Sciences, University of Bergen, Bergen, Norway
| | - Tom O Nilsen
- Department of Biological Sciences, University of Bergen, Bergen, Norway.,NORCE, Norwegian Research Centre, NORCE Environment, Bergen, Norway
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5
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Wood CM, Pelster B, Braz-Mota S, Val AL. Gills versus kidney for ionoregulation in the obligate air-breathing Arapaima gigas, a fish with a kidney in its air-breathing organ. J Exp Biol 2020; 223:jeb232694. [PMID: 32895323 DOI: 10.1242/jeb.232694] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2020] [Accepted: 08/19/2020] [Indexed: 12/19/2022]
Abstract
In Arapaima gigas, an obligate air-breather endemic to ion-poor Amazonian waters, a large complex kidney runs through the air-breathing organ (ABO). Previous indirect evidence suggested that the kidney, relative to the small gills, may be exceptionally important in ionoregulation and nitrogen (N) waste excretion, with support of kidney function by direct O2 supply from the airspace. We tested these ideas by continuous urine collection and gill flux measurements in ∼700 g fish. ATPase activities were many-fold greater in kidney than gills. In normoxia, gill Na+ influx and efflux were in balance, with net losses of Cl- and K+ Urine flow rate (UFR, ∼11 ml kg-1 h-1) and urinary ions (< 0.2 mmol l-1) were exceptional, with [urine]:[plasma] ratios of 0.02-0.002 for K+, Na+, and Cl-, indicating strong reabsorption with negligible urinary ion losses. Urinary [ammonia] was very high (10 mmol l-1, [urine]:[plasma] ∼17) indicating strong secretion. The kidney accounted for 21-24% of N excretion, with ammonia dominating (95%) over urea-N through both routes. High urinary [ammonia] was coupled to high urinary [HCO3-]. Aerial hypoxia (15.3 kPa) and aerial hyperoxia (>40.9 kPa) had no effects on UFR, but both inhibited branchial Na+ influx, revealing novel aspects of the osmorespiratory compromise. Aquatic hypoxia (4.1 kPa), but not aquatic hyperoxia (>40.9 kPa), inhibited gill Na+ influx, UFR and branchial and urinary ammonia excretion. We conclude that the kidney is more important than gills in ionoregulation, and is significant in N excretion. Although not definitive, our results do not indicate direct O2 supply from the ABO for kidney function.
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Affiliation(s)
- 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
| | - Bernd Pelster
- Institute of Zoology, University of Innsbruck, Innsbruck A-6020, Austria
- Center for Molecular Biosciences, University Innsbruck, Innsbruck A-6020, Austria
| | - Susana Braz-Mota
- Laboratory of Ecophysiology and Molecular Evolution, Brazilian National Institute for Research of the Amazon, Manaus 69080-971, Brazil
| | - Adalberto L Val
- Laboratory of Ecophysiology and Molecular Evolution, Brazilian National Institute for Research of the Amazon, Manaus 69080-971, Brazil
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6
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Sunga J, Wilson JM, Wilkie MP. Functional re-organization of the gills of metamorphosing sea lamprey (Petromyzon marinus): preparation for a blood diet and the freshwater to seawater transition. J Comp Physiol B 2020; 190:701-715. [PMID: 32852575 DOI: 10.1007/s00360-020-01305-1] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2019] [Revised: 05/31/2020] [Accepted: 06/18/2020] [Indexed: 11/28/2022]
Abstract
Sea lamprey (Petromyzon marinus) begin life as filter-feeding larvae (ammocoetes) before undergoing a complex metamorphosis into parasitic juveniles, which migrate to the sea where they feed on the blood of large-bodied fishes. The greater protein intake during this phase results in marked increases in the production of nitrogenous wastes (N-waste), which are excreted primarily via the gills. However, it is unknown how gill structure and function change during metamorphosis and how it is related to modes of ammonia excretion, nor do we have a good understanding of how the sea lamprey's transition from fresh water (FW) to sea water (SW) affects patterns and mechanisms of N-waste excretion in relation to ionoregulation. Using immunohistochemistry, we related changes in the gill structure of larval, metamorphosing, and juvenile sea lampreys to their patterns of ammonia excretion (Jamm) and urea excretion (Jurea) in FW, and following FW to artificial seawater (ASW) transfer. Rates of Jamm and Jurea were low in larval sea lamprey and increased in feeding juvenile, parasitic sea lamprey. In freshwater-dwelling ammocoetes, immunohistochemical analysis revealed that Rhesus glycoprotein C-like protein (Rhcg-like) was diffusely distributed on the lamellar epithelium, but following metamorphosis, Rhcg-like protein was restricted to SW mitochondrion-rich cells (MRCs; ionocytes) between the gill lamellae. Notably, these interlamellar Rhcg-like proteins co-localized with Na+/K+-ATPase (NKA), which increased in expression and activity by almost tenfold during metamorphosis. The distribution of V-type H+-ATPase (V-ATPase) on the lamellae decreased following metamorphosis, indicating it may have a more important role in acid-base regulation and Na+ uptake in FW, compared to SW. We conclude that the re-organization of the sea lamprey gill during metamorphosis not only plays a critical role in allowing them to cope with greater salinity following the FW-SW transition, but that it simultaneously reflects fundamental changes in methods used to excrete ammonia.
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Affiliation(s)
- Julia Sunga
- Department of Biology and Laurier Institute for Water Science, Wilfrid Laurier University, Waterloo, ON, N2L 3C5, Canada
| | - Jonathan M Wilson
- Department of Biology and Laurier Institute for Water Science, Wilfrid Laurier University, Waterloo, ON, N2L 3C5, Canada
| | - Michael P Wilkie
- Department of Biology and Laurier Institute for Water Science, Wilfrid Laurier University, Waterloo, ON, N2L 3C5, Canada.
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7
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Fehsenfeld S, Wood CM. A potential role for hyperpolarization-activated cyclic nucleotide-gated sodium/potassium channels (HCNs) in teleost acid-base and ammonia regulation. Comp Biochem Physiol B Biochem Mol Biol 2020; 248-249:110469. [PMID: 32653509 DOI: 10.1016/j.cbpb.2020.110469] [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: 05/11/2020] [Revised: 06/24/2020] [Accepted: 07/02/2020] [Indexed: 11/27/2022]
Abstract
Increasing evidence suggests the involvement of hyperpolarization-activated cyclic nucleotide-gated sodium/potassium channels (HCNs) not only in cardiac and neural function, but also in more general physiological processes including acid-base and ammonia regulation. We have identified four different HCN paralogs/isoforms in the goldfish Carassius auratus (CaHCN1, CaHCN2b, CaHCN4a and CaHCN4b) as likely candidates to contribute to renal, branchial and intestinal acid-base and ammonia regulation in this teleost. Quantitative real-time PCR showed not only high mRNA abundance of all isoforms in heart and brain, but also detectable levels (particularly of CaHCN2b and CaHCN4b) in non-excitable tissues, including gills and kidneys. In response to an internal or external acid-base and/or ammonia disturbance caused by feeding or high environmental ammonia, respectively, we observed differential and tissue-specific changes in mRNA abundance of all isoforms except CaHCN4b. Furthermore, our data suggest that the functions of specific HCN channels are supplemented by certain Rhesus glycoprotein functions to help in the protection of tissues from elevated ammonia levels, or as potential direct routes for ammonia transport in gills, kidney, and gut. The present results indicate important individual roles for each HCN isoform in response to acid-base and ammonia disturbances.
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Affiliation(s)
- Sandra Fehsenfeld
- Université du Quebec à Rimouski, Département de biologie, chimie et géographie, 300 Allée des Ursulines, Rimouski, QC G5L 3A1, Canada; University of British Columbia, Department of Zoology, 4200 - 6270 University Blvd., Vancouver, BC V6T 1Z4, Canada.
| | - Chris M Wood
- University of British Columbia, Department of Zoology, 4200 - 6270 University Blvd., Vancouver, BC V6T 1Z4, Canada
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8
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L'Honoré T, Farcy E, Blondeau-Bidet E, Lorin-Nebel C. Inter-individual variability in freshwater tolerance is related to transcript level differences in gill and posterior kidney of European sea bass. Gene 2020; 741:144547. [PMID: 32165299 DOI: 10.1016/j.gene.2020.144547] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2019] [Revised: 01/30/2020] [Accepted: 03/08/2020] [Indexed: 02/06/2023]
Abstract
Acclimation to low salinities is a vital physiological challenge for euryhaline fish as the European sea bass Dicentrarchus labrax. This species undertakes seasonal migrations towards lagoons and estuaries where a wide range of salinity variations occur along the year. We have previously reported intraspecific differences in freshwater tolerance, with an average 30% mortality rate. In this study, we bring new evidence of mechanisms underlying freshwater tolerance in sea bass at gill and kidney levels. In fresh water (FW), intraspecific differences in mRNA expression levels of several ion transporters and prolactin receptors were measured. We showed that the branchial Cl-/HCO3- anion transporter (slc26a6c) was over-expressed in freshwater intolerant fish, probably as a compensatory response to low blood chloride levels and potential metabolic alkalosis. Moreover, prolactin receptor a (prlra) and Na+/Cl- cotransporter (ncc1) but not ncc-2a expression seemed to be slightly increased and highly variable between individuals in freshwater intolerant fish. In the posterior kidney, freshwater intolerant fish exhibited differential expression levels of slc26 anion transporters and Na+/K+/2Cl- cotransporter 1b (nkcc1b). Lower expression levels of prolactin receptors (prlra, prlrb) were measured in posterior kidney which probably contributes to the failure in ion reuptake at the kidney level. Freshwater intolerance seems to be a consequence of renal failure of ion reabsorption, which is not sufficiently compensated at the branchial level.
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Affiliation(s)
- Thibaut L'Honoré
- Univ Montpellier, MARBEC (CNRS, IFREMER, IRD, UM), Montpellier, France
| | - Emilie Farcy
- Univ Montpellier, MARBEC (CNRS, IFREMER, IRD, UM), Montpellier, France
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9
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Burggren W, Bautista N. Invited review: Development of acid-base regulation in vertebrates. Comp Biochem Physiol A Mol Integr Physiol 2019; 236:110518. [DOI: 10.1016/j.cbpa.2019.06.018] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2019] [Revised: 06/24/2019] [Accepted: 06/25/2019] [Indexed: 12/26/2022]
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10
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Fehsenfeld S, Kolosov D, Wood CM, O'Donnell MJ. Section-specific H + flux in renal tubules of fasted and fed goldfish. ACTA ACUST UNITED AC 2019; 222:jeb.200964. [PMID: 31138633 DOI: 10.1242/jeb.200964] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2019] [Accepted: 05/21/2019] [Indexed: 12/12/2022]
Abstract
A recent study demonstrated that in response to a feeding-induced metabolic acidosis, goldfish (Carassius auratus) adjust epithelial protein and/or mRNA expression in their kidney tubules for multiple transporters known to be relevant for acid-base regulation. These include Na+/H+ exchanger (NHE), V-type H+-ATPase (V-ATPase), cytoplasmic carbonic anhydrase, HCO3 - transporters and Rhesus proteins. Consequently, renal acid output in the form of protons and NH4 + increases. However, little is known about the mechanistic details of renal acid-base regulation in C. auratus and teleost fishes in general. The present study applied the scanning ion-selective electrode technique (SIET) to measure proton flux in proximal, distal and connecting tubules of goldfish. We detected increased H+ efflux into the extracellular fluid from the tubule in fed animals, resulting from paracellular back-flux of H+ through the tight junction. By applying inhibitors for selected acid-base regulatory epithelial transporters, we found that cytosolic carbonic anhydrase and HCO3 - transporters were important in mediating H+ flux in all three tubule segments of fed goldfish. Contrastingly, V-ATPase seemed to play a role in H+ flux only in proximal and distal tubules, and NHE in proximal and connecting tubules. We developed working models for transport of acid-base relevant equivalents (H+, HCO3 -, NH3/NH4 +) for each tubule segment in C. auratus kidney. While the proximal tubule appears to play a major role in both H+ secretion and HCO3 - reabsorption, the distal and connecting tubules seem to mainly serve for HCO3 - reabsorption and NH3/NH4 + secretion.
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Affiliation(s)
- Sandra Fehsenfeld
- Département de Biologie, Chimie et Géographie, Université du Québec à Rimouski, Rimouski, QC, G5L 3A1, Canada .,Department of Zoology, University of British Columbia, Vancouver, BC, V6T 1Z4, Canada
| | - Dennis Kolosov
- Department of Biology, McMaster University, Hamilton, ON, L8S 4K1, Canada
| | - Chris M Wood
- Department of Zoology, University of British Columbia, Vancouver, BC, V6T 1Z4, Canada.,Department of Biology, McMaster University, Hamilton, ON, L8S 4K1, Canada
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