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Yamaguchi Y, Ikeba K, Yoshida MA, Takagi W. Molecular basis of the unique osmoregulatory strategy in the inshore hagfish, Eptatretus burgeri. Am J Physiol Regul Integr Comp Physiol 2024; 327:R208-R233. [PMID: 38105762 DOI: 10.1152/ajpregu.00166.2023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2023] [Revised: 12/05/2023] [Accepted: 12/11/2023] [Indexed: 12/19/2023]
Abstract
Hagfishes are characterized by omo- and iono-conforming nature similar to marine invertebrates. Conventionally, hagfishes had been recognized as the most primitive living vertebrate that retains plesiomorphic features. However, some of the "ancestral" features of hagfishes, such as rudimentary eyes and the lack of vertebrae, have been proven to be deceptive. Similarly, by the principle of maximum parsimony, the unique body fluid regulatory strategy of hagfishes seems to be apomorphic, since the lamprey, another cyclostome, adopts osmo- and iono-regulatory mechanisms as in jawed vertebrates. Although hagfishes are unequivocally important in discussing the origin and evolution of the vertebrate osmoregulatory system, the molecular basis for the body fluid homeostasis in hagfishes has been poorly understood. In the present study, we explored this matter in the inshore hagfish, Eptatretus burgeri, by analyzing the transcriptomes obtained from the gill, kidney, and muscle of the animals acclimated to distinct environmental salinities. Together with the measurement of parameters in the muscular fluid compartment, our data indicate that the hagfish possesses an ability to conduct free amino acid (FAA)-based osmoregulation at a cellular level, which is in coordination with the renal and branchial FAA absorption. We also revealed that the hagfish does possess the orthologs of the known osmoregulatory genes and that the transepithelial movement of inorganic ions in the hagfish gill and kidney is more complex than previously thought. These observations pose a challenge to the conventional view that the physiological features of hagfishes have been inherited from the last common ancestor of the extant vertebrates.
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Affiliation(s)
- Yoko Yamaguchi
- Institute of Agricultural and Life Sciences, Academic Assembly, Shimane University, Matsue, Japan
| | - Kiriko Ikeba
- Laboratory of Physiology, Atmosphere and Ocean Research Institute, The University of Tokyo, Kashiwa, Japan
| | - Masa-Aki Yoshida
- Institute of Agricultural and Life Sciences, Academic Assembly, Shimane University, Matsue, Japan
- Marine Biological Science Section, Education and Research Center for Biological Resources, Faculty of Life and Environmental Science, Shimane University, Okinoshima, Japan
| | - Wataru Takagi
- Laboratory of Physiology, Atmosphere and Ocean Research Institute, The University of Tokyo, Kashiwa, Japan
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2
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Zimmer AM. Ammonia excretion by the fish gill: discoveries and ideas that shaped our current understanding. J Comp Physiol B 2024:10.1007/s00360-024-01561-5. [PMID: 38849577 DOI: 10.1007/s00360-024-01561-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2023] [Revised: 03/06/2024] [Accepted: 05/15/2024] [Indexed: 06/09/2024]
Abstract
The fish gill serves many physiological functions, among which is the excretion of ammonia, the primary nitrogenous waste in most fishes. Although it is the end-product of nitrogen metabolism, ammonia serves many physiological functions including acting as an acid equivalent and as a counter-ion in mechanisms of ion regulation. Our current understanding of the mechanisms of ammonia excretion have been influenced by classic experimental work, clever mechanistic approaches, and modern molecular and genetic techniques. In this review, I will overview the history of the study of ammonia excretion by the gills of fishes, highlighting the important advancements that have shaped this field with a nearly 100-year history. The developmental and evolutionary implications of an ammonia and gill-dominated nitrogen regulation strategy in most fishes will also be discussed. Throughout the review, I point to areas in which more work is needed to push forward this field of research that continues to produce novel insights and discoveries that will undoubtedly shape our overall understanding of fish physiology.
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Affiliation(s)
- Alex M Zimmer
- Department of Biological Sciences, University of New Brunswick, 100 Tucker Park Road, Saint John, Saint John, New Brunswick, E2L 4L5, Canada.
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3
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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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Breves JP, Shaughnessy CA. Endocrine control of gill ionocyte function in euryhaline fishes. J Comp Physiol B 2024:10.1007/s00360-024-01555-3. [PMID: 38739280 DOI: 10.1007/s00360-024-01555-3] [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: 01/08/2024] [Revised: 02/16/2024] [Accepted: 04/11/2024] [Indexed: 05/14/2024]
Abstract
The endocrine system is an essential regulator of the osmoregulatory organs that enable euryhaline fishes to maintain hydromineral balance in a broad range of environmental salinities. Because branchial ionocytes are the primary site for the active exchange of Na+, Cl-, and Ca2+ with the external environment, their functional regulation is inextricably linked with adaptive responses to changes in salinity. Here, we review the molecular-level processes that connect osmoregulatory hormones with branchial ion transport. We focus on how factors such as prolactin, growth hormone, cortisol, and insulin-like growth-factors operate through their cognate receptors to direct the expression of specific ion transporters/channels, Na+/K+-ATPases, tight-junction proteins, and aquaporins in ion-absorptive (freshwater-type) and ion-secretory (seawater-type) ionocytes. While these connections have historically been deduced in teleost models, more recently, increased attention has been given to understanding the nature of these connections in basal lineages. We conclude our review by proposing areas for future investigation that aim to fill gaps in the collective understanding of how hormonal signaling underlies ionocyte-based processes.
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Affiliation(s)
- Jason P Breves
- Department of Biology, Skidmore College, 815 N. Broadway, Saratoga Springs, NY, 12866, USA.
| | - Ciaran A Shaughnessy
- Department of Integrative Biology, Oklahoma State University, 501 Life Sciences West, Stillwater, OK, 74078, USA
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5
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Breves JP, Runiewicz ER, Richardson SG, Bradley SE, Hall DJ, McCormick SD. Transcriptional regulation of esophageal, intestinal, and branchial solute transporters by salinity, growth hormone, and cortisol in Atlantic salmon. JOURNAL OF EXPERIMENTAL ZOOLOGY. PART A, ECOLOGICAL AND INTEGRATIVE PHYSIOLOGY 2024; 341:107-117. [PMID: 38010889 DOI: 10.1002/jez.2766] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/31/2023] [Revised: 11/05/2023] [Accepted: 11/08/2023] [Indexed: 11/29/2023]
Abstract
In marine habitats, Atlantic salmon (Salmo salar) imbibe seawater (SW) to replace body water that is passively lost to the ambient environment. By desalinating consumed SW, the esophagus enables solute-linked water absorption across the intestinal epithelium. The processes underlying esophageal desalination in salmon and their hormonal regulation during smoltification and following SW exposure are unresolved. To address this, we considered whether two Na+ /H+ exchangers (Nhe2 and -3) expressed in the esophagus contribute to the uptake of Na+ from lumenal SW. There were no seasonal changes in esophageal nhe2 or -3 expression during smoltification; however, nhe3 increased following 48 h of SW exposure in May. Esophageal nhe2, -3, and growth hormone receptor b1 were elevated in smolts acclimated to SW for 2.5 weeks. Treatment with cortisol stimulated branchial Na+ /K+ -ATPase (Nka) activity, and Na+ /K+ /2Cl- cotransporter 1 (nkcc1), cystic fibrosis transmembrane regulator 1 (cftr1), and nka-α1b expression. Esophageal nhe2, but not nhe3 expression, was stimulated by cortisol. In anterior intestine, cortisol stimulated nkcc2, cftr2, and nka-α1b. Our findings indicate that salinity stimulates esophageal nhe2 and -3, and that cortisol coordinates the expression of esophageal, intestinal, and branchial solute transporters to support the SW adaptability of Atlantic salmon.
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Affiliation(s)
- Jason P Breves
- Department of Biology, Skidmore College, Saratoga Springs, New York, USA
| | - Ellie R Runiewicz
- Department of Biology, Skidmore College, Saratoga Springs, New York, USA
| | | | - Serena E Bradley
- Department of Biology, Skidmore College, Saratoga Springs, New York, USA
| | - Daniel J Hall
- Department of Biology, University of Massachusetts, Amherst, Massachusetts, USA
| | - Stephen D McCormick
- Department of Biology, University of Massachusetts, Amherst, Massachusetts, USA
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Tresguerres M, Kwan GT, Weinrauch A. Evolving views of ionic, osmotic and acid-base regulation in aquatic animals. J Exp Biol 2023; 226:jeb245747. [PMID: 37522267 DOI: 10.1242/jeb.245747] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/01/2023]
Abstract
The regulation of ionic, osmotic and acid-base (IOAB) conditions in biological fluids is among the most fundamental functions in all organisms; being surrounded by water uniquely shapes the IOAB regulatory strategies of water-breathing animals. Throughout its centennial history, Journal of Experimental Biology has established itself as a premier venue for publication of comparative, environmental and evolutionary studies on IOAB regulation. This Review provides a synopsis of IOAB regulation in aquatic animals, some of the most significant research milestones in the field, and evolving views about the underlying cellular mechanisms and their evolutionary implications. It also identifies promising areas for future research and proposes ideas for enhancing the impact of aquatic IOAB research.
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Affiliation(s)
- Martin Tresguerres
- Scripps Institution of Oceanography, University of California, San Diego, La Jolla, CA 92037, USA
| | - Garfield T Kwan
- Department of Wildlife, Fish, and Conservation Biology, University of California, Davis, Davis, CA 95616, USA
| | - Alyssa Weinrauch
- Department of Biological Sciences, University of Manitoba, Winnipeg, MB R3T 2M5, Canada
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Lee CE, Charmantier G, Lorin-Nebel C. Mechanisms of Na + uptake from freshwater habitats in animals. Front Physiol 2022; 13:1006113. [PMID: 36388090 PMCID: PMC9644288 DOI: 10.3389/fphys.2022.1006113] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2022] [Accepted: 09/28/2022] [Indexed: 07/20/2023] Open
Abstract
Life in fresh water is osmotically and energetically challenging for living organisms, requiring increases in ion uptake from dilute environments. However, mechanisms of ion uptake from freshwater environments are still poorly understood and controversial, especially in arthropods, for which several hypothetical models have been proposed based on incomplete data. One compelling model involves the proton pump V-type H+ ATPase (VHA), which energizes the apical membrane, enabling the uptake of Na+ (and other cations) via an unknown Na+ transporter (referred to as the "Wieczorek Exchanger" in insects). What evidence exists for this model of ion uptake and what is this mystery exchanger or channel that cooperates with VHA? We present results from studies that explore this question in crustaceans, insects, and teleost fish. We argue that the Na+/H+ antiporter (NHA) is a likely candidate for the Wieczorek Exchanger in many crustaceans and insects; although, there is no evidence that this is the case for fish. NHA was discovered relatively recently in animals and its functions have not been well characterized. Teleost fish exhibit redundancy of Na+ uptake pathways at the gill level, performed by different ion transporter paralogs in diverse cell types, apparently enabling tolerance of low environmental salinity and various pH levels. We argue that much more research is needed on overall mechanisms of ion uptake from freshwater habitats, especially on NHA and other potential Wieczorek Exchangers. Such insights gained would contribute greatly to our general understanding of ionic regulation in diverse species across habitats.
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Affiliation(s)
- Carol Eunmi Lee
- Department of Integrative Biology, University of Wisconsin, Madison, WI, United States
- MARBEC, Univ Montpellier, CNRS, Ifremer, IRD, Montpellier, France
| | - Guy Charmantier
- MARBEC, Univ Montpellier, CNRS, Ifremer, IRD, Montpellier, France
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Zhu S, Yan X, Shen C, Wu L, Tang D, Wang Y, Wang Z. Transcriptome analysis of the gills of Eriocheir sinensis provide novel insights into the molecular mechanisms of the pH stress response. Gene 2022; 833:146588. [PMID: 35598683 DOI: 10.1016/j.gene.2022.146588] [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: 10/06/2021] [Revised: 04/26/2022] [Accepted: 05/16/2022] [Indexed: 11/04/2022]
Abstract
Eriocheir sinensis is an important economic species in China, which is easily affected by pH changes. However, the molecular mechanism of the pH stress response in E. sinensis is still unclear. Therefore, this study aimed to examine the molecular response mechanism of E. sinensis based on pH variation surveillance, histopathological evaluation and transcriptomic analyses. Firstly, pH variation surveillance showed that E. sinensis could actively regulate the pH of its environment. Meanwhile, the histopathological evaluation suggested that pH stress seriously damaged the gills, especially at high pH. Finally, transcriptome analysis showed that the expression of genes related to ion transport, immune stress, and energy metabolism significantly changed. Many genes played an important role in the pH response of E. sinensis, such as carbonic anhydrase (CA), mitochondrial proton/calcium exchanger protein (LETM1), recombinant sodium/hydrogen exchanger 3 (SLC9A3/NHE3), heat shock protein 90 alpha family class a member (HSP90A), alkylglycerone phosphate synthase (AGPS), succinate-CoA ligase ADP-forming subunit beta (LSC2), and superoxide dismutase (SOD). Our study revealed the molecular response mechanism of E. sinensis in response to pH stress, thus providing a basis for further research on the molecular mechanism of response to pH stress in aquatic animals.
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Affiliation(s)
- Shang Zhu
- Jiangsu Key Laboratory for Bioresources of Saline Soils, Jiangsu Synthetic Innovation Center for Coastal Bio-agriculture, Jiangsu Provincial Key Laboratory of Coastal Wetland Bioresources and Environmental Protection, School of Wetlands, Yancheng Teachers University, Yancheng 224001, Jiangsu Province, China
| | - Xinyao Yan
- Jiangsu Key Laboratory for Bioresources of Saline Soils, Jiangsu Synthetic Innovation Center for Coastal Bio-agriculture, Jiangsu Provincial Key Laboratory of Coastal Wetland Bioresources and Environmental Protection, School of Wetlands, Yancheng Teachers University, Yancheng 224001, Jiangsu Province, China
| | - Chenchen Shen
- Jiangsu Key Laboratory for Bioresources of Saline Soils, Jiangsu Synthetic Innovation Center for Coastal Bio-agriculture, Jiangsu Provincial Key Laboratory of Coastal Wetland Bioresources and Environmental Protection, School of Wetlands, Yancheng Teachers University, Yancheng 224001, Jiangsu Province, China
| | - Lv Wu
- Jiangsu Key Laboratory for Bioresources of Saline Soils, Jiangsu Synthetic Innovation Center for Coastal Bio-agriculture, Jiangsu Provincial Key Laboratory of Coastal Wetland Bioresources and Environmental Protection, School of Wetlands, Yancheng Teachers University, Yancheng 224001, Jiangsu Province, China
| | - Dan Tang
- Jiangsu Key Laboratory for Bioresources of Saline Soils, Jiangsu Synthetic Innovation Center for Coastal Bio-agriculture, Jiangsu Provincial Key Laboratory of Coastal Wetland Bioresources and Environmental Protection, School of Wetlands, Yancheng Teachers University, Yancheng 224001, Jiangsu Province, China; College of Biotechnology and Pharmaceutical Engineering, Nanjing Tech University, Nanjing 211800, Jiangsu Province, China
| | - Yue Wang
- Jiangsu Key Laboratory for Bioresources of Saline Soils, Jiangsu Synthetic Innovation Center for Coastal Bio-agriculture, Jiangsu Provincial Key Laboratory of Coastal Wetland Bioresources and Environmental Protection, School of Wetlands, Yancheng Teachers University, Yancheng 224001, Jiangsu Province, China
| | - Zhengfei Wang
- Jiangsu Key Laboratory for Bioresources of Saline Soils, Jiangsu Synthetic Innovation Center for Coastal Bio-agriculture, Jiangsu Provincial Key Laboratory of Coastal Wetland Bioresources and Environmental Protection, School of Wetlands, Yancheng Teachers University, Yancheng 224001, Jiangsu Province, China.
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Genome-wide identification of the NHE gene family in Coilia nasus and its response to salinity challenge and ammonia stress. BMC Genomics 2022; 23:526. [PMID: 35858854 PMCID: PMC9297642 DOI: 10.1186/s12864-022-08761-9] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2022] [Accepted: 07/13/2022] [Indexed: 11/25/2022] Open
Abstract
Background In aquatic environments, pH, salinity, and ammonia concentration are extremely important for aquatic animals. NHE is a two-way ion exchange carrier protein, which can transport Na+ into cells and exchange out H+, and also plays key roles in regulating intracellular pH, osmotic pressure, and ammonia concentration. Results In the present study, ten NHEs, the entire NHE gene family, were identified from Coilia nasus genome and systemically analyzed via phylogenetic, structural, and synteny analysis. Different expression patterns of C. nasus NHEs in multiple tissues indicated that expression profiles of NHE genes displayed tissue-specific. Expression patterns of C. nasus NHEs were related to ammonia excretion during multiple embryonic development stages. To explore the potential functions on salinity challenge and ammonia stress, expression levels of ten NHEs were detected in C. nasus gills under hypotonic stress, hypertonic stress, and ammonia stress. Expression levels of all NHEs were upregulated during hypotonic stress, while they were downregulated during hypertonic stress. NHE2 and NHE3 displayed higher expression levels in C. nasus larvae and juvenile gills under ammonia stress. Conclusions Our study revealed that NHE genes played distinct roles in embryonic development, salinity stress, and ammonia exposure. Syntenic analysis showed significant difference between stenohaline fish and euryhaline fishes. Our findings will provide insight into effects of C. nasus NHE gene family on ion transport and ammonia tolerance and be beneficial for healthy aquaculture of C. nasus. Supplementary Information The online version contains supplementary material available at 10.1186/s12864-022-08761-9.
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Zhao H, Wang Q, Zhao H, Chen C. Transcriptome profiles revealed high- and low-salinity water altered gill homeostasis in half-smooth tongue sole (Cynoglossus semilaevis). COMPARATIVE BIOCHEMISTRY AND PHYSIOLOGY. PART D, GENOMICS & PROTEOMICS 2022; 42:100989. [PMID: 35421665 DOI: 10.1016/j.cbd.2022.100989] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/24/2022] [Revised: 03/27/2022] [Accepted: 04/06/2022] [Indexed: 06/14/2023]
Abstract
Salinity is an important environmental factor that affects fish growth, development, and reproduction. As euryhaline fish, half-smooth tongue sole (Cynoglossus semilaevis) are a suitable species for deciphering the salinity adaptation mechanism of fish; however, the molecular mechanisms underlying low- and high-salinity responses remain unclear. In this study, RNA-seq was applied to characterize the genes and regulatory pathways involved in C. semilaevis gill responses to high- (32 ppt), low- (8 ppt), and control-salinity (24 ppt) water. Gills were rich in mitochondria-rich cells (MRCs) in high salinity. Compared with control, 2137 and 218 differentially expressed genes (DEGs) were identified in low and high salinity, respectively. The enriched functions of most DEGs were metabolism, ion transport, regulation of cell cycle, and immune response. The DEGs involved in oxidative phosphorylation, citrate cycle, and fatty acid metabolism were down-regulated in low salinity. For ion transport, high and low salinity significantly altered the expressions of prlr, ca12, and cftr. In cell cycle arrest and cellular repair, gadd45b, igfbp5, and igfbp2 were significantly upregulated in high and low salinity. For immune response, il10, il34, il12b, and crp increased in high and low salinity. Our findings suggested that alterations in material and energy metabolism, ions transport, cell cycle arrest, cellular repair, and immune response, are required to maintain C. semilaevis gill homeostasis under high and low salinity. This study provides insight into the divergence of C. semilaevis osmoregulation mechanisms acclimating to high and low salinity, which will serve as reference for the healthy culture of C. semilaevis.
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Affiliation(s)
- Huiyan Zhao
- Tianjin Key Laboratory of Aqua-Ecology and Aquaculture, Tianjin 300392, China; College of Fisheries, Tianjin Agricultural University, Tianjin 300392, China
| | - Qingkui Wang
- Tianjin Key Laboratory of Aqua-Ecology and Aquaculture, Tianjin 300392, China; College of Fisheries, Tianjin Agricultural University, Tianjin 300392, China.
| | - Honghao Zhao
- Tianjin Key Laboratory of Aqua-Ecology and Aquaculture, Tianjin 300392, China; College of Fisheries, Tianjin Agricultural University, Tianjin 300392, China
| | - Chengxun Chen
- Tianjin Key Laboratory of Aqua-Ecology and Aquaculture, Tianjin 300392, China; College of Fisheries, Tianjin Agricultural University, Tianjin 300392, China
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Zhou B, Qi D, Liu S, Qi H, Wang Y, Zhao K, Tian F. Physiological, morphological and transcriptomic responses of Tibetan naked carps (Gymnocypris przewalskii) to salinity variations. COMPARATIVE BIOCHEMISTRY AND PHYSIOLOGY. PART D, GENOMICS & PROTEOMICS 2022; 42:100982. [PMID: 35279439 DOI: 10.1016/j.cbd.2022.100982] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/19/2022] [Revised: 03/03/2022] [Accepted: 03/03/2022] [Indexed: 11/30/2022]
Abstract
Gymnocypris przewalskii is a native cyprinid fish that dwells in the Lake Qinghai with salinity of 12-13‰. It migrates annually to the freshwater rivers for spawning, experiencing the significant changes in salinity. In the present study, we performed the physiological, morphological and transcriptomic analyses to understand the osmoregulation in G. przewalskii. The physiological assay showed that the osmotic pressure of G. przewalskii was almost isosmotic to the brackish lake water. The low salinity reduced its ionic concentrations and osmotic pressure. The plasticity of gill microstructure was linked to the salinity variations, including the presence of mucus and intact tight junctions in brackish water and the development of the mitochondria-rich cells and the loosened tight junctions in freshwater. RNA-seq analysis identified 1926 differentially expressed genes, including 710 and 1216 down- and up-regulated genes in freshwater, which were enriched in ion transport, cell-cell adhesion, and mucus secretion. Genes in ion uptake were activated in low salinity, and mucus pathways and tight junction showed the higher transcription in brackish water. The isosmoticity between the body fluid and the environment suggested G. przewalskii was in the metabolic-saving condition in the brackish water. The decreased salinity disrupted this balance, which activated the ion uptake in freshwater to maintain osmotic homeostasis. The gill remodeling was involved in this process through the development of the mitochondria-rich cells to enhance ion uptake. The current finding provided insights into the potential mechanisms of G. przewalskii to cope with salinity alteration.
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Affiliation(s)
- Bingzheng Zhou
- Key Laboratory of Adaptation and Evolution of Plateau Biota, Qinghai Provincial Key Laboratory of Animal Ecological Genomics, Northwest Institute of Plateau Biology, Chinese Academy of Sciences, Xining 810008, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Delin Qi
- State Key Laboratory of Plateau Ecology and Agriculture, College of Eco-Environmental Engineering, Qinghai University, Xining 810008, China
| | - Sijia Liu
- Key Laboratory of Adaptation and Evolution of Plateau Biota, Qinghai Provincial Key Laboratory of Animal Ecological Genomics, Northwest Institute of Plateau Biology, Chinese Academy of Sciences, Xining 810008, China
| | - Hongfang Qi
- Qinghai Provincial Key Laboratory of Gymnocypris przewalskii breeding and reproduction, Xining 810008, China
| | - Yang Wang
- Qinghai Provincial Key Laboratory of Gymnocypris przewalskii breeding and reproduction, Xining 810008, China
| | - Kai Zhao
- Key Laboratory of Adaptation and Evolution of Plateau Biota, Qinghai Provincial Key Laboratory of Animal Ecological Genomics, Northwest Institute of Plateau Biology, Chinese Academy of Sciences, Xining 810008, China
| | - Fei Tian
- Key Laboratory of Adaptation and Evolution of Plateau Biota, Qinghai Provincial Key Laboratory of Animal Ecological Genomics, Northwest Institute of Plateau Biology, Chinese Academy of Sciences, Xining 810008, China.
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12
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Romersi RF, Nicklisch SCT. Interactions of Environmental Chemicals and Natural Products With ABC and SLC Transporters in the Digestive System of Aquatic Organisms. Front Physiol 2022; 12:767766. [PMID: 35095552 PMCID: PMC8793745 DOI: 10.3389/fphys.2021.767766] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2021] [Accepted: 11/18/2021] [Indexed: 12/03/2022] Open
Abstract
An organism’s diet is a major route of exposure to both beneficial nutrients and toxic environmental chemicals and natural products. The uptake of dietary xenobiotics in the intestine is prevented by transporters of the Solute Carrier (SLC) and ATP Binding Cassette (ABC) family. Several environmental chemicals and natural toxins have been identified to induce expression of these defense transporters in fish and aquatic invertebrates, indicating that they are substrates and can be eliminated. However, certain environmental chemicals, termed Transporter-Interfering Chemicals or TICs, have recently been shown to bind to and inhibit fish and mammalian P-glycoprotein (ABCB1), thereby sensitizing cells to toxic chemical accumulation. If and to what extent other xenobiotic defense or nutrient uptake transporters can also be inhibited by dietary TICs is still unknown. To date, most chemical-transporter interaction studies in aquatic organisms have focused on ABC-type transporters, while molecular interactions of xenobiotics with SLC-type transporters are poorly understood. In this perspective, we summarize current advances in the identification, localization, and functional analysis of protective MXR transporters and nutrient uptake systems in the digestive system of fish and aquatic invertebrates. We collate the existing literature data on chemically induced transporter gene expression and summarize the molecular interactions of xenobiotics with these transport systems. Our review emphasizes the need for standardized assays in a broader panel of commercially important fish and seafood species to better evaluate the effects of TIC and other xenobiotic interactions with physiological substrates and MXR transporters across the aquatic ecosystem and predict possible transfer to humans through consumption.
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Breves JP, Nelson NN, Koltenyuk V, Petro-Sakuma CK, Celino-Brady FT, Seale AP. Enhanced expression of ncc1 and clc2c in the kidney and urinary bladder accompanies freshwater acclimation in Mozambique tilapia. Comp Biochem Physiol A Mol Integr Physiol 2021; 260:111021. [PMID: 34174427 PMCID: PMC8355173 DOI: 10.1016/j.cbpa.2021.111021] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2021] [Revised: 06/19/2021] [Accepted: 06/21/2021] [Indexed: 11/15/2022]
Abstract
Euryhaline fishes maintain hydromineral balance in a broad range of environmental salinities via the activities of multiple osmoregulatory organs, namely the gill, gastrointestinal tract, skin, kidney, and urinary bladder. Teleosts residing in freshwater (FW) environments are faced with the diffusive loss of ions and the osmotic gain of water, and, therefore, the kidney and urinary bladder reabsorb Na+ and Cl- to support the production of dilute urine. Nonetheless, the regulated pathways for Na+ and Cl- transport by euryhaline fishes, especially in the urinary bladder, have not been fully resolved. Here, we first investigated the ultrastructure of epithelial cells within the urinary bladder of FW-acclimated Mozambique tilapia (Oreochromis mossambicus) by electron microscopy. We then investigated whether tilapia employ Na+/Cl- cotransporter 1 (Ncc1) and Clc family Cl- channel 2c (Clc2c) for the reabsorption of Na+ and Cl- by the kidney and urinary bladder. We hypothesized that levels of their associated gene transcripts vary inversely with environmental salinity. In whole kidney and urinary bladder homogenates, ncc1 and clc2c mRNA levels were markedly higher in steady-state FW- versus SW (seawater)-acclimated tilapia. Following transfer from SW to FW, ncc1 and clc2c in both the kidney and urinary bladder were elevated within 48 h. A concomitant increase in branchial ncc2, and decreases in Na+/K+/2Cl-cotransporter 1a (nkcc1a) and cystic fibrosis transmembrane regulator 1 (cftr1) levels indicated a transition from Na+ and Cl- secretion to absorption by the gills in parallel with the identified renal and urinary bladder responses to FW transfer. Our findings suggest that Ncc1 and Clc2c contribute to the functional plasticity of the kidney and urinary bladder in tilapia.
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Affiliation(s)
- Jason P Breves
- Department of Biology, Skidmore College, Saratoga Springs, NY 12866, USA.
| | - Nastasia N Nelson
- Department of Biology, Skidmore College, Saratoga Springs, NY 12866, USA
| | - Victor Koltenyuk
- Department of Biology, Skidmore College, Saratoga Springs, NY 12866, USA
| | - Cody K Petro-Sakuma
- Department of Human Nutrition, Food and Animal Sciences, University of Hawai'i at Mānoa, 1955 East-West Road, Honolulu, HI 96822, USA
| | - Fritzie T Celino-Brady
- Department of Human Nutrition, Food and Animal Sciences, University of Hawai'i at Mānoa, 1955 East-West Road, Honolulu, HI 96822, USA
| | - Andre P Seale
- Department of Human Nutrition, Food and Animal Sciences, University of Hawai'i at Mānoa, 1955 East-West Road, Honolulu, HI 96822, USA
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14
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Chen X, Gong H, Chi H, Xu B, Zheng Z, Bai Y. Gill Transcriptome Analysis Revealed the Difference in Gene Expression Between Freshwater and Seawater Acclimated Guppy (Poecilia reticulata). MARINE BIOTECHNOLOGY (NEW YORK, N.Y.) 2021; 23:615-627. [PMID: 34426939 DOI: 10.1007/s10126-021-10053-4] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/10/2021] [Accepted: 07/09/2021] [Indexed: 06/13/2023]
Abstract
Guppy (Poecilia reticulata) can adapt to a wide range of salinity changes. To investigate the gene expression changes in the guppy exposed to seawater, we characterized its gill transcriptome using RNA sequencing. Experimental fish were exposed to salinity increase from 0 to 30‰ within 4 days, while control fish were cultured in freshwater (0‰ salinity). Seven days after salinity exposure, the gills were sampled and the mortality within 2 weeks was recorded. No significant difference in the cumulative mortality at the second week was found between the two groups. Transcriptomic analysis identified 3477 differentially expressed genes (DEGs), including 1067 upregulated and 2410 downregulated genes. These DEGs were enriched in several biological processes, including ion transport, ion homeostasis, ATP biosynthetic process, metabolic process, and immune system process. Oxidative phosphorylation was the most activated pathway. DEGs involved in the pathway "endoplasmic reticulum (ER)-mediated phagocytosis," "starch and sucrose metabolism," and "steroid biosynthesis" were mainly downregulated; chemokines and interleukins involved in "cytokine-cytokine receptor interaction" were differentially expressed. The present results suggested that oxidative phosphorylation had essential roles in osmoregulation in the gills of seawater acclimated guppy, during which the decline in the expression of genes encoding V-ATPases and calreticulin had a negative effect on the phagocytosis and immune response. Besides, several metabolic processes including "starch and sucrose metabolism" and "steroid biosynthesis" were affected. This study elucidates transcriptomic changes in osmotic regulation, metabolism, and immunity in seawater acclimated guppy.
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Affiliation(s)
- Xiuxia Chen
- Biotechnology Institute, Fujian Academy of Agricultural Sciences, Fuzhou, China
| | - Hui Gong
- Biotechnology Institute, Fujian Academy of Agricultural Sciences, Fuzhou, China.
| | - Hongshu Chi
- Biotechnology Institute, Fujian Academy of Agricultural Sciences, Fuzhou, China
| | - Binfu Xu
- Biotechnology Institute, Fujian Academy of Agricultural Sciences, Fuzhou, China
| | - Zaiyu Zheng
- Biotechnology Institute, Fujian Academy of Agricultural Sciences, Fuzhou, China
| | - Yulin Bai
- State Key Laboratory of Marine Environmental Science, College of Ocean and Earth Sciences, Xiamen University, Xiamen, China
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15
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Lin CH, Hu HJ, Chuang HJ, Tsou YL, Hwang PP. Cortisol and glucocorticoid receptor 2 regulate acid secretion in medaka (Oryzias latipes) larvae. J Comp Physiol B 2021; 191:855-864. [PMID: 34274982 DOI: 10.1007/s00360-021-01390-w] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2020] [Revised: 05/19/2021] [Accepted: 07/06/2021] [Indexed: 11/26/2022]
Abstract
Freshwater fish live in environments where pH levels fluctuate more than those in seawater. During acidic stress, the acid-base balance in these fish is regulated by ionocytes in the gills, which directly contact water and function as an external kidney. In ionocytes, apical acid secretion is largely mediated by H+-ATPase and the sodium/hydrogen exchanger (NHE). Control of this system was previously proposed to depend on the hormone, cortisol, mostly based on studies of zebrafish, a stenohaline fish, which utilize H+-ATPase as the main route for apical acid secretion. However, the role of cortisol is poorly understood in euryhaline fish species that preferentially use NHE as the main transporter. In the present study, we explored the role of cortisol in NHE-mediated acid secretion in medaka larvae. mRNA expression levels of transporters related to acid secretion and cortisol-synthesis enzyme were enhanced by acidic FW treatment (pH 4.5, 2 days) in medaka larvae. Moreover, exogenous cortisol treatment (25 mg/L, 2 days) resulted in upregulation of nhe3 and rhcg1 expression, as well as acid secretion in 7 dpf medaka larvae. In loss-of-function experiments, microinjection of glucocorticoid receptor (GR)2 morpholino (MO) caused reductions in nhe3 and rhcg1 expression and diminished acid secretion, but microinjection of mineralocorticoid receptor (MR) and GR1 MOs did not. Together, these results suggest a conserved action of cortisol and GR2 on fish body fluid acid-base regulation.
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Affiliation(s)
- Chia-Hao Lin
- Department of Marine Biotechnology, National Kaohsiung University of Science and Technology, Kaohsiung, 81143, Taiwan.
- The iEGG and Animal Biotechnology Center, National Chung Hsing University, Taichung, 40227, Taiwan.
| | - Huei-Jyun Hu
- Institute of Cellular and Organismic Biology, Academia Sinica, Taipei, 11529, Taiwan
| | - Hsin-Ju Chuang
- Institute of Cellular and Organismic Biology, Academia Sinica, Taipei, 11529, Taiwan
- Department of Life Science, National Taiwan University, Taipei, 10607, Taiwan
| | - Yi-Ling Tsou
- Institute of Cellular and Organismic Biology, Academia Sinica, Taipei, 11529, Taiwan
| | - Pung-Pung Hwang
- Institute of Cellular and Organismic Biology, Academia Sinica, Taipei, 11529, Taiwan.
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16
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Zimmer AM, Goss GG, Glover CN. Reductionist approaches to the study of ionoregulation in fishes. Comp Biochem Physiol B Biochem Mol Biol 2021; 255:110597. [PMID: 33781928 DOI: 10.1016/j.cbpb.2021.110597] [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: 01/05/2021] [Revised: 03/15/2021] [Accepted: 03/22/2021] [Indexed: 10/21/2022]
Abstract
The mechanisms underlying ionoregulation in fishes have been studied for nearly a century, and reductionist methods have been applied at all levels of biological organization in this field of research. The complex nature of ionoregulatory systems in fishes makes them ideally suited to reductionist methods and our collective understanding has been dramatically shaped by their use. This review provides an overview of the broad suite of techniques used to elucidate ionoregulatory mechanisms in fishes, from the whole-animal level down to the gene, discussing some of the advantages and disadvantages of these methods. We provide a roadmap for understanding and appreciating the work that has formed the current models of organismal, endocrine, cellular, molecular, and genetic regulation of ion balance in fishes and highlight the contribution that reductionist techniques have made to some of the fundamental leaps forward in the field throughout its history.
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Affiliation(s)
- Alex M Zimmer
- Department of Biological Sciences, CW 405, Biological Sciences Bldg., University of Alberta, Edmonton, AB T6G 2E9, Canada.
| | - Greg G Goss
- Department of Biological Sciences, CW 405, Biological Sciences Bldg., University of Alberta, Edmonton, AB T6G 2E9, Canada
| | - Chris N Glover
- Department of Biological Sciences, CW 405, Biological Sciences Bldg., University of Alberta, Edmonton, AB T6G 2E9, Canada; Faculty of Science and Technology and Athabasca River Basin Research Institute, Athabasca University, Athabasca, AB T9S 3A3, Canada
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17
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Blair S, Li X, Dutta D, Chamot D, Fliegel L, Goss G. Rainbow Trout ( Oncorhynchus mykiss) Na +/H + Exchangers tNhe3a and tNhe3b Display Unique Inhibitory Profiles Dissimilar from Mammalian NHE Isoforms. Int J Mol Sci 2021; 22:ijms22042205. [PMID: 33672216 PMCID: PMC7926675 DOI: 10.3390/ijms22042205] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2021] [Revised: 02/17/2021] [Accepted: 02/20/2021] [Indexed: 01/05/2023] Open
Abstract
Freshwater fishes maintain an internal osmolality of ~300 mOsm, while living in dilute environments ranging from 0 to 50 mOsm. This osmotic challenge is met at least partially, by Na+/H+ exchangers (NHE) of fish gill and kidney. In this study, we cloned, expressed, and pharmacologically characterized fish-specific Nhes of the commercially important species Oncorhynchus mykiss. Trout (t) Nhe3a and Nhe3b isoforms from gill and kidney were expressed and characterized in an NHE-deficient cell line. Western blotting and immunocytochemistry confirmed stable expression of the tagged trout tNhe proteins. To measure NHE activity, a transient acid load was induced in trout tNhe expressing cells and intracellular pH was measured. Both isoforms demonstrated significant activity and recovered from an acute acid load. The effect of the NHE transport inhibitors amiloride, EIPA (5-(N-ethyl-N-isopropyl)-amiloride), phenamil, and DAPI was examined. tNhe3a was inhibited in a dose-dependent manner by amiloride and EIPA and tNhe3a was more sensitive to amiloride than EIPA, unlike mammalian NHE1. tNhe3b was inhibited by high concentrations of amiloride, while even in the presence of high concentrations of EIPA (500 µM), some activity of tNhe3b remained. Phenamil and DAPI were ineffective at inhibiting tNhe activity of either isoform. The current study aids in understanding the pharmacology of fish ion transporters. Both isoforms display inhibitory profiles uniquely different from mammalian NHEs and show resistance to inhibition. Our study allows for more direct interpretation of past, present, and future fish-specific sodium transport studies, with less reliance on mammalian NHE data for interpretation.
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Affiliation(s)
- Salvatore Blair
- Department of Biology, Winthrop University, Rock Hill, SC 29733, USA;
- Department of Biological Sciences, University of Alberta, Edmonton, AB T6G 2E9, Canada;
| | - Xiuju Li
- Department of Biochemistry, University of Alberta, Edmonton, AB T6G 2H7, Canada; (X.L.); (D.D.); (L.F.)
| | - Debajyoti Dutta
- Department of Biochemistry, University of Alberta, Edmonton, AB T6G 2H7, Canada; (X.L.); (D.D.); (L.F.)
| | - Danuta Chamot
- Department of Biological Sciences, University of Alberta, Edmonton, AB T6G 2E9, Canada;
| | - Larry Fliegel
- Department of Biochemistry, University of Alberta, Edmonton, AB T6G 2H7, Canada; (X.L.); (D.D.); (L.F.)
| | - Greg Goss
- Department of Biological Sciences, University of Alberta, Edmonton, AB T6G 2E9, Canada;
- Correspondence: ; Tel.: +1-780-492-1276; Fax: +1-780-492-9234
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18
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Barnawi EA, Doherty JE, Ferreira PG, Wilson JM. Extra-gastric expression of the proton pump H +/K +-ATPase in the gills and kidney of the teleost Oreochromis niloticus. J Exp Biol 2020; 223:jeb214890. [PMID: 32611790 DOI: 10.1242/jeb.214890] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2019] [Accepted: 06/26/2020] [Indexed: 12/12/2022]
Abstract
Potassium regulation is essential for the proper functioning of excitable tissues in vertebrates. The H+/K+-ATPase (HKA), which is composed of the HKα1 (gene: atp4a) and HKβ (gene: atp4b) subunits, has an established role in potassium and acid-base regulation in mammals and is well known for its role in gastric acidification. However, the role of HKA in extra-gastric organs such as the gill and kidney is less clear, especially in fishes. In the present study in Nile tilapia, Oreochromis niloticus, uptake of the K+ surrogate flux marker rubidium (Rb+) was demonstrated in vivo; however, this uptake was not inhibited with omeprazole, a potent inhibitor of the gastric HKA. This contrasts with gill and kidney ex vivo preparations, where tissue Rb+ uptake was significantly inhibited by omeprazole and SCH28080, another gastric HKA inhibitor. The cellular localization of this pump in both the gill and kidney was demonstrated using immunohistochemical techniques with custom-made antibodies specific for Atp4a and Atp4b. Antibodies against the two subunits showed the same apical ionocyte distribution pattern in the gill and collecting tubules/ducts in the kidney. Atp4a antibody specificity was confirmed by western blotting. RT-PCT was used to confirm the expression of both subunits in the gill and kidney. Taken together, these results indicate for the first time K+ (Rb+) uptake in O. niloticus and that HKA is implicated, as shown through the ex vivo uptake inhibition by omeprazole and SCH28080, verifying a role for HKA in K+ absorption in the gill's ionocytes and collecting tubule/duct segments of the kidney.
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Affiliation(s)
- Ebtesam Ali Barnawi
- Department of Biology, Wilfrid Laurier University, Waterloo, ON, Canada, N2L 3C5
| | - Justine E Doherty
- Department of Biology, Wilfrid Laurier University, Waterloo, ON, Canada, N2L 3C5
| | | | - Jonathan M Wilson
- Department of Biology, Wilfrid Laurier University, Waterloo, ON, Canada, N2L 3C5
- Molecular Physiology, Centro Interdisciplinar de Investigação Marinha e Ambiental, 4450-208 Matosinhos, Portugal
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19
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Wichmann L, Althaus M. Evolution of epithelial sodium channels: current concepts and hypotheses. Am J Physiol Regul Integr Comp Physiol 2020; 319:R387-R400. [PMID: 32783689 DOI: 10.1152/ajpregu.00144.2020] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
The conquest of freshwater and terrestrial habitats was a key event during vertebrate evolution. Occupation of low-salinity and dry environments required significant osmoregulatory adaptations enabling stable ion and water homeostasis. Sodium is one of the most important ions within the extracellular liquid of vertebrates, and molecular machinery for urinary reabsorption of this electrolyte is critical for the maintenance of body osmoregulation. Key ion channels involved in the fine-tuning of sodium homeostasis in tetrapod vertebrates are epithelial sodium channels (ENaCs), which allow the selective influx of sodium ions across the apical membrane of epithelial cells lining the distal nephron or the colon. Furthermore, ENaC-mediated sodium absorption across tetrapod lung epithelia is crucial for the control of liquid volumes lining the pulmonary surfaces. ENaCs are vertebrate-specific members of the degenerin/ENaC family of cation channels; however, there is limited knowledge on the evolution of ENaC within this ion channel family. This review outlines current concepts and hypotheses on ENaC phylogeny and discusses the emergence of regulation-defining sequence motifs in the context of osmoregulatory adaptations during tetrapod terrestrialization. In light of the distinct regulation and expression of ENaC isoforms in tetrapod vertebrates, we discuss the potential significance of ENaC orthologs in osmoregulation of fishes as well as the putative fates of atypical channel isoforms in mammals. We hypothesize that ancestral proton-sensitive ENaC orthologs might have aided the osmoregulatory adaptation to freshwater environments whereas channel regulation by proteases evolved as a molecular adaptation to lung liquid homeostasis in terrestrial tetrapods.
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Affiliation(s)
- Lukas Wichmann
- Institute for Animal Physiology, Justus Liebig University, Giessen, Germany
| | - Mike Althaus
- Department of Natural Sciences, Bonn-Rhein-Sieg University of Applied Sciences, Rheinbach, Germany
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20
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Griffith MB, Lazorchak JM, Haring H. Uptake of Sulfate from Ambient Water by Freshwater Animals. WATER 2020; 12:1-1496. [PMID: 32704397 PMCID: PMC7376752 DOI: 10.3390/w12051496] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
To better understand how the sulfate (SO4 2-) anion may contribute to the adverse effects associated with elevated ionic strength or salinity in freshwaters, we measured the uptake and efflux of SO4 2- in four freshwater species: the fathead minnow (Pimephales promelas, Teleostei: Cyprinidae), paper pondshell (Utterbackia imbecillis, Bivalvia: Unionidae), red swamp crayfish (Procambarus clarkii, Crustacea: Cambaridae), and two-lined mayfly (Hexagenia bilineata, Insecta: Ephemeridae). Using δ( 34 S/ 32 S) stable isotope ratios and the concentrations of S and SO4 2-, we measured the SO4 2- influx rate (J in ), net flux (J net ), and efflux rate (Jout) during a 24 h exposure period. For all four species, the means of J in for SO4 2- were positive, and J in was significantly greater than 0 at both target SO4 2- concentrations in the fish and mollusk and at the lower SO4 2- concentration in the crayfish. The means of J out and J net were much more variable than those for J in , but several species by target SO4 2- concentration combinations for J out and J net , were negative, which suggests the net excretion of SO4 2- by the animals. The results of our experiments suggest a greater regulation of SO4 2- in freshwater animals than has been previously reported.
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Affiliation(s)
- Michael B. Griffith
- U.S. Environmental Protection Agency, Office of Research and Development, National Center for Environmental Assessment, Cincinnati, OH 45268, USA
- U.S. Environmental Protection Agency, Office of Research and Development, Center for Environmental Measurement and Modeling, Cincinnati, OH 45268, USA
| | - James M. Lazorchak
- U.S. Environmental Protection Agency, Office of Research and Development, Center for Environmental Measurement and Modeling, Cincinnati, OH 45268, USA
- U.S. Environmental Protection Agency, Office of Research and Development, National Exposure Research Laboratory, Cincinnati, OH 45268, USA
| | - Herman Haring
- Pegasus Technical Services, Inc., Cincinnati, OH 45268, USA
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21
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Malakpour Kolbadinezhad S, Coimbra J, Wilson JM. Is the dendritic organ of the striped eel catfish Plotosus lineatus an ammonia excretory organ? Comp Biochem Physiol A Mol Integr Physiol 2019; 241:110640. [PMID: 31870932 DOI: 10.1016/j.cbpa.2019.110640] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2019] [Revised: 12/13/2019] [Accepted: 12/16/2019] [Indexed: 11/24/2022]
Abstract
The dendritic organ (DO) is a salt secretory organ in the Plotosidae marine catfishes. The potential role of the DO in ammonia excretion was investigated by examining the effects of salinity [brackishwater (BW 3‰), seawater (SW 34‰) and hypersaline water (HSW 60‰)] acclimation and DO ligation on ammonia excretion and ammonia transporter expression by immunohistochemistry (IHC), immunoblotting (IB) and qPCR. Ammonia flux rates (JAmm) were significantly lower in BW compared to SW and HSW. DO ligation resulted in a significantly lower JAmm in SW but not BW fish. IHC demonstrated apical and basolateral localization of Rhesus-associated glycoprotein (Rhag-like) and Rhbg-like proteins, respectively, in parenchymal cells of the DO acini. In the gills, which are the primary site of ammonia excretion in teleost fishes, IHC showed an apical localization of Rhag-like protein in some Na+/K+-ATPase (NKA) immunoreactive (IR) cells limited to a few interlamellar regions of the filament and, in both apical and basolateral membranes of pillar cells irrespective of treatment group. In gills, the distribution of NKA-IR cells showed no salinity and/or ligation dependency. IB of Rhag and Rhbg-like proteins was found only in the gills and expression levels did not change with salinity but ligation in BW decreased Rhbg-like levels. Although Rhcg was not detected with heterologous antibodies, rhcg1 mRNA expression was detected in both gills and DO. HSW was associated with the lowest expression in DO and ligations in SW and BW were without effect on branchial expression levels. Taken together these results indicate the DO potentially has a physiological role in ammonia excretion under SW conditions.
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Affiliation(s)
- Salman Malakpour Kolbadinezhad
- Centro Interdisciplinar de Investigação Marinha e Ambiental (CIIMAR/CIMAR), Universidade do Porto, Porto, Portugal; Instituto de Ciências Biomédicas de Abel Salazar (ICBAS), Universidade do Porto, Porto, Portugal; Coldwater Fisheries Research Center (CFRC), Iranian Fisheries Sciences Research Institute (IFSRI), Agricultural Research, Education and Extension Organization, Tonekabon, Iran.
| | - João Coimbra
- Centro Interdisciplinar de Investigação Marinha e Ambiental (CIIMAR/CIMAR), Universidade do Porto, Porto, Portugal; Instituto de Ciências Biomédicas de Abel Salazar (ICBAS), Universidade do Porto, Porto, Portugal.
| | - Jonathan M Wilson
- Centro Interdisciplinar de Investigação Marinha e Ambiental (CIIMAR/CIMAR), Universidade do Porto, Porto, Portugal; Instituto de Ciências Biomédicas de Abel Salazar (ICBAS), Universidade do Porto, Porto, Portugal; Department of Biology, Wilfrid Laurier University, Waterloo, Canada.
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22
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Nunan BL, Silva AS, Wang T, da Silva GS. Respiratory control of acid-base status in lungfish. Comp Biochem Physiol A Mol Integr Physiol 2019; 237:110533. [DOI: 10.1016/j.cbpa.2019.110533] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2019] [Revised: 07/02/2019] [Accepted: 07/31/2019] [Indexed: 01/19/2023]
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23
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Effect of salinity and temperature on the expression of genes involved in branchial ion transport processes in European sea bass. J Therm Biol 2019; 85:102422. [DOI: 10.1016/j.jtherbio.2019.102422] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2019] [Revised: 09/05/2019] [Accepted: 09/17/2019] [Indexed: 12/24/2022]
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Wong MKS, Nobata S, Hyodo S. Enhanced osmoregulatory ability marks the smoltification period in developing chum salmon (Oncorhynchus keta). Comp Biochem Physiol A Mol Integr Physiol 2019; 238:110565. [PMID: 31493553 DOI: 10.1016/j.cbpa.2019.110565] [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: 06/03/2019] [Revised: 08/29/2019] [Accepted: 08/30/2019] [Indexed: 11/29/2022]
Abstract
The freshwater (FW) life of chum salmon is short, as they migrate to the ocean soon after emergence from the substrate gravel of natal waters. The alevins achieve seawater (SW) acclimating ability at an early developmental stage and the details of smoltification are not clear. We examined the stage-dependent SW acclimating ability in chum salmon alevins and found a sharp increase in SW tolerance during development that resembles the physiological parr-smolt transformation seen in other salmonids. Perturbation of plasma Na+ after SW exposure was prominent from the hatched embryo stage to emerged alevins, but the plasma Na+ became highly stable and more resistant to perturbation soon after complete absorption of yolk. Marker gene expression for SW-ionocytes including Na/K-ATPase (NKA α1b), Na-K-Cl cotransporter 1a (NKCC1a), Na/H exchanger 3a (NHE3a), cystic fibrosis transmembrane conductance regulators (CFTR I and CFTR II) were all upregulated profoundly at the same stage when the alevins were challenged by SW, suggesting that the stability of plasma Na+ concentration was partly a result of elevated osmoregulatory capability. FW-ionocyte markers including NKA α1a and NHE3b were consistently downregulated independent of stage by SW exposure, suggesting that embryos at all stages respond to salinity challenge, but the increase in SW osmoregulatory capability is restricted to the developmental stage after emergence. We propose that the "smoltification period" is condensed and integrated into the early development of chum salmon, and our results can be extrapolated to the future studies on hormonal controls and developmental triggers for smoltification in salmonids.
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Affiliation(s)
- Marty Kwok-Shing Wong
- Laboratory of Physiology, Atmosphere and Ocean Research Institute, The University of Tokyo, Chiba, Japan.
| | - Shigenori Nobata
- International Coastal Research Center, Atmosphere and Ocean Research Institute, the University of Tokyo, Otsuchi, Iwate, Japan
| | - Susumu Hyodo
- Laboratory of Physiology, Atmosphere and Ocean Research Institute, The University of Tokyo, Chiba, Japan
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25
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Ion uptake pathways in European sea bass Dicentrarchus labrax. Gene 2019; 692:126-137. [DOI: 10.1016/j.gene.2019.01.006] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2018] [Revised: 12/12/2018] [Accepted: 01/02/2019] [Indexed: 01/20/2023]
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26
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Liu Y, Wen H, Qi X, Zhang X, Zhang K, Fan H, Tian Y, Hu Y, Li Y. Genome-wide identification of the Na+/H+ exchanger gene family in Lateolabrax maculatus and its involvement in salinity regulation. COMPARATIVE BIOCHEMISTRY AND PHYSIOLOGY D-GENOMICS & PROTEOMICS 2019; 29:286-298. [DOI: 10.1016/j.cbd.2019.01.001] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/08/2018] [Revised: 01/03/2019] [Accepted: 01/04/2019] [Indexed: 01/21/2023]
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Lema SC, Carvalho PG, Egelston JN, Kelly JT, McCormick SD. Dynamics of Gene Expression Responses for Ion Transport Proteins and Aquaporins in the Gill of a Euryhaline Pupfish during Freshwater and High-Salinity Acclimation. Physiol Biochem Zool 2019; 91:1148-1171. [PMID: 30334669 DOI: 10.1086/700432] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
Pupfishes (genus Cyprinodon) evolved some of the broadest salinity tolerances of teleost fishes, with some taxa surviving in conditions from freshwater to nearly 160 ppt. In this study, we examined transcriptional dynamics of ion transporters and aquaporins in the gill of the desert Amargosa pupfish (Cyprinodon nevadensis amargosae) during rapid salinity change. Pupfish acclimated to 7.5 ppt were exposed to freshwater (0.3 ppt), seawater (35 ppt), or hypersaline (55 ppt) conditions over 4 h and sampled at these salinities over 14 d. Plasma osmolality and Cl- concentration became elevated 8 h after the start of exposure to 35 or 55 ppt but returned to baseline levels after 14 d. Osmolality recovery was paralleled by increased gill Na+/K+-ATPase activity and higher relative levels of messenger RNAs (mRNAs) encoding cystic fibrosis transmembrane conductance regulator (cftr) and Na+/K+/2Cl- cotransporter-1 (nkcc1). Transcripts encoding one Na+-HCO3- cotransporter-1 isoform (nbce1.1) also increased in the gills at higher salinities, while a second isoform (nbce1.2) increased expression in freshwater. Pupfish in freshwater also had lower osmolality and elevated gill mRNAs for Na+/H+ exchanger isoform-2a (nhe2a) and V-type H+-ATPase within 8 h, followed by increases in Na+/H+ exchanger-3 (nhe3), carbonic anhydrase 2 (ca2), and aquaporin-3 (aqp3) within 1 d. Gill mRNAs for Na+/Cl- cotransporter-2 (ncc2) also were elevated 14 d after exposure to 0.3 ppt. These results offer insights into how coordinated transcriptional responses for ion transporters in the gill facilitate reestablishment of osmotic homeostasis after changes in environmental salinity and provide evidence that the teleost gill expresses two Na+-HCO3- cotransporter-1 isoforms with different roles in freshwater and seawater acclimation.
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Brauner CJ, Shartau RB, Damsgaard C, Esbaugh AJ, Wilson RW, Grosell M. Acid-base physiology and CO2 homeostasis: Regulation and compensation in response to elevated environmental CO2. FISH PHYSIOLOGY 2019. [DOI: 10.1016/bs.fp.2019.08.003] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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29
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Martin KE, Ehrman JM, Wilson JM, Wright PA, Currie S. Skin ionocyte remodeling in the amphibious mangrove rivulus fish (Kryptolebias marmoratus
). JOURNAL OF EXPERIMENTAL ZOOLOGY PART 2018; 331:128-138. [DOI: 10.1002/jez.2247] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/22/2018] [Revised: 10/24/2018] [Accepted: 10/25/2018] [Indexed: 12/19/2022]
Affiliation(s)
- Keri E. Martin
- Department of Biology, Mount Allison University; Sackville New Brunswick Canada
| | - James M. Ehrman
- Department of Biology, Mount Allison University; Sackville New Brunswick Canada
| | - Jonathan M. Wilson
- Department of Biology, Wilfrid Laurier University; Waterloo Ontario Canada
| | - Patricia A. Wright
- Department of Integrative Biology, University of Guelph; Guelph Ontario Canada
| | - Suzanne Currie
- Department of Biology, Mount Allison University; Sackville New Brunswick Canada
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Fehsenfeld S, Wood CM. Section-specific expression of acid-base and ammonia transporters in the kidney tubules of the goldfish Carassius auratus and their responses to feeding. Am J Physiol Renal Physiol 2018; 315:F1565-F1582. [PMID: 30089033 DOI: 10.1152/ajprenal.00510.2017] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
In teleost fishes, renal contributions to acid-base and ammonia regulation are often neglected compared with the gills. In goldfish, increased renal acid excretion in response to feeding was indicated by increased urine ammonia and inorganic phosphate concentrations and decreased urine pH. By microdissecting the kidney tubules and performing quantitative real-time PCR and/or immunohistochemistry, we profiled the section-specific expression of glutamate dehydrogenase (GDH), glutamine synthetase (GS), Na+/H+-exchanger 3 (NHE3), carbonic anhydrase II (CAIIa), V-H+-ATPase subunit 1b, Cl-/ HCO3- -exchanger 1 (AE1), Na+/ HCO3- -cotransporter 1 (NBC1), Na+/K+-ATPase subunit 1α, and Rhesus-proteins Rhbg, Rhcg1a, and Rhcg1b. Here, we show for the first time that 1) the proximal tubule appears to be the major site for ammoniagenesis, 2) epithelial transporters are differentially expressed along the renal tubule, and 3) a potential feeding-related "acidic tide" results in the differential regulation of epithelial transporters, resembling the mammalian renal response to a metabolic acidosis. Specifically, GDH and NHE3 mRNAs were upregulated and GS downregulated in the proximal tubule upon feeding, suggesting this section as a major site for ammoniagenesis and acid secretion. The distal tubule may play a major role in renal ammonia secretion, with feeding-induced upregulation of mRNA and protein for apical NHE3, cytoplasmic CAIIa, universal Rhcg1a and apical Rhcg1b, and downregulation of basolateral Rhbg and AE1. Changes in mRNA expression of the Wolffian ducts and bladder suggest supporting roles in fine-tuning urine composition. The present study verifies an important renal contribution to acid-base balance and emphasizes that studies looking at the whole kidney may overlook key section-specific responses.
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Affiliation(s)
- Sandra Fehsenfeld
- University of British Columbia, Department of Zoology , Vancouver , Canada
| | - Chris M Wood
- University of British Columbia, Department of Zoology , Vancouver , Canada
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Brannen M, Gilmour KM. Carbonic anhydrase expression in the branchial ionocytes of rainbow trout. J Exp Biol 2018; 221:jeb.164582. [DOI: 10.1242/jeb.164582] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2017] [Accepted: 01/22/2018] [Indexed: 12/13/2022]
Abstract
Rainbow trout (Oncorhynchus mykiss) exposed to acid-base challenges activate branchial mechanisms for the excretion of acid-base equivalents. Current models of branchial acid-base excretion in freshwater rainbow trout propose two main ionocyte types; the peanut lectin agglutinin-positive (PNA+) mitochondrion-rich cell or ionocyte is believed to secrete HCO3− in exchange for Cl−, whereas H+ secretion is thought to occur across PNA− ionocytes in exchange for Na+. Both HCO3− and H+ are supplied by intracellular hydration of CO2 catalyzed by cytosolic carbonic anhydrase (CAc). Immunohistochemical approaches revealed that under control conditions, CAc was detectable in 92.3±1.0% (N=11) of PNA− ionocytes, and the abundance of PNA− ionocytes increased in response to systemic acidosis elicited by 72 h exposure to water of low pH (nominally pH 4.5), hypercapnia (1% CO2, nominally 7.6 Torr) or hyperoxia (achieved by gassing water with pure O2), as did the abundance of PNA− ionocytes that exhibited immunofluorescence for CAc. However, just 4.3 ± 0.6% (N=11) of PNA+ ionocytes expressed detectable CAc under control conditions. Marked increases in the abundance of CAc-positive PNA+ ionocytes were detected following exposure of trout to a base load via recovery from hypercapnia, or base infusion (72 h infusion with 140 mmol L−1 NaHCO3). The percentage of CAc-positive PNA+ ionocytes also was increased in trout treated with cortisol (10 mg kg−1 hydrocortisone 21-hemisuccinate daily for 7 d). These results suggest that regulation of CA within PNA+ ionocytes and/or the abundance of CAc-positive PNA+ ionocytes plays a role in activating base secretion in response to systemic alkalosis.
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Affiliation(s)
- Michael Brannen
- Department of Biology, University of Ottawa, Ottawa, Ontario, Canada
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Esbaugh AJ, Cutler B. Intestinal Na+, K+, 2Cl- cotransporter 2 plays a crucial role in hyperosmotic transitions of a euryhaline teleost. Physiol Rep 2017; 4:4/22/e13028. [PMID: 27881573 PMCID: PMC5358003 DOI: 10.14814/phy2.13028] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2016] [Revised: 10/06/2016] [Accepted: 10/07/2016] [Indexed: 11/29/2022] Open
Abstract
Euryhaline fishes, such as the red drum (Sciaenops ocellatus), must quickly transition between hyperosmotic and hypoosmotic physiological strategies. When freshwater individuals transition to seawater they are exposed to increased diffusive water loss and ion gain. To maintain osmoregulatory balance these animals must drink and absorb seawater through the intestine, followed by ion excretion at the gills. The ability of fishes to transition between strategies can limit the magnitude of osmotic shock that can be tolerated. Here, we demonstrate that red drum can tolerate direct transfer from freshwater to full‐strength seawater with marginal impacts on osmotic balance, as indicated by plasma and muscle ion concentration, as well as muscle water. Seawater transition is concurrent with a significant increase in intestinal fluid volume. Typical patterns of osmoregulatory plasticity were observed in the gill with increased expression of nkcc1 and cftr. Expression changes in the anterior intestine were observed after 24 h for nkcc2 with smaller and later responses observed for slc26a3, slc26a6, and nbc. Immunofluorescence staining demonstrated similar patterns of NKCC localization in freshwater and seawater intestines; however, reduced basolateral staining of V‐type ATPase was observed in seawater. Electrophysiological preparations demonstrated that seawater fish had increased absorptive current in the anterior intestine, which was significantly reduced in the presence of 10 μmol/L bumetanide. Overall, these results suggest that nkcc2 plays a crucial role during hyperosmotic transitions, and may be a more important complement to the well‐known bicarbonate secretion pathway than generally considered.
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Affiliation(s)
- Andrew J Esbaugh
- University of Texas at Austin Marine Science Institute, Austin, Texas
| | - Brett Cutler
- University of Texas at Austin Marine Science Institute, Austin, Texas
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Adlimoghaddam A, O’Donnell MJ, Quijada-Rodriguez A, Weihrauch D. Sodium–hydrogen exchangers in the nematode Caenorhabditis elegans: investigations towards their potential role in hypodermal H+ excretion, Na+ uptake, and ammonia excretion, as well as acid–base balance. CAN J ZOOL 2017. [DOI: 10.1139/cjz-2016-0243] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Cation/proton exchangers of the cation proton antiporter 1 (CPA1) subfamily (NHEs, SLC 9) play an important role in many physiological processes, including cell volume regulation, acid–base homeostasis, and ammonia excretion. The soil nematode Caenorhabditis elegans (Maupas, 1900) (N2, 1968) expresses nine paralogues (NHX-1 to NHX-9). The current study was undertaken to investigate the role of the cation/proton exchanger in hypodermal Na+ and H+ fluxes, as well in ammonia excretion processes. Measurements using SIET (scanning ion-selective electrode technique) showed that the hypodermis promotes H+ secretion and Na+ uptake. Inhibitory effects on fluxes were observed upon application of amiloride but not EIPA, suggesting that NHXs are not involved in the transport processes. In response to stress induced by starvation or exposure to 1 mmol·L−1 NH4Cl, pH 5.5, or pH 8.0, body pH stayed fairly constant, with changes in mRNA expression levels detected in intestinal NHX-2 and hypodermal NHX-3. In conclusion, the study suggest that hypodermal apically localized EIPA-sensitive Na+/H+ exchangers do not likely play a role in ammonia excretion and Na+ uptake in the hypodermis of C. elegans, whereas apical amiloride-sensitive Na+ channels seem to be involved not just in hypodermal Na+ uptake but indirectly also in NH4+ and H+ excretion.
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Affiliation(s)
- Aida Adlimoghaddam
- Department of Biological Sciences, University of Manitoba, Winnipeg, MB R3T 2N2, Canada
| | | | | | - Dirk Weihrauch
- Department of Biological Sciences, University of Manitoba, Winnipeg, MB R3T 2N2, Canada
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Quijada-Rodriguez AR, Schultz AG, Wilson JM, He Y, Allen GJP, Goss GG, Weihrauch D. Ammonia-independent sodium uptake mediated by Na + channels and NHEs in the freshwater ribbon leech Nephelopsis obscura. ACTA ACUST UNITED AC 2017; 220:3270-3279. [PMID: 28684464 DOI: 10.1242/jeb.159459] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2017] [Accepted: 07/03/2017] [Indexed: 12/18/2022]
Abstract
Freshwater organisms actively take up ions from their environment to counter diffusive ion losses due to inhabiting hypo-osmotic environments. The mechanisms behind active Na+ uptake are quite well understood in freshwater teleosts; however, the mechanisms employed by invertebrates are not. Pharmacological and molecular approaches were used to investigate Na+ uptake mechanisms and their link to ammonia excretion in the ribbon leech Nephelopsis obscura At the molecular level, we identified a Na+ channel and a Na+/H+ exchanger (NHE) in the skin of N. obscura, where the NHE was up-regulated when acclimated to extremely low [Na+] (0.05 mmol l-1, pH 5) conditions. Additionally, we found that leeches in dilute freshwater environments use both a vacuolar-type H+-ATPase (VHA)-assisted uptake via a Na+ channel and a NHE-based mechanisms for Na+ uptake. Immunolocalization of VHA and Na+/K+-ATPase (NKA) indicated at least two cell types present within leech skin, VHA+ and VHA- cells, where the VHA+ cells are probably involved in Na+ uptake. NKA was present throughout the epithelium. We also found that increasing ammonia excretion by decreasing water pH, ammonia loading leeches or exposing leeches to high environmental ammonia does not affect Na+ uptake, providing indications that an NHE-Rh metabolon is not present and that ammonia excretion and Na+ uptake are not coupled in N. obscura To our knowledge, this is the first study showing the mechanisms of Na+ uptake and their links to ammonia excretion in a freshwater invertebrate, where results suggest an ammonia-independent Na+ uptake mechanism relying on both Na+ channels and NHEs.
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Affiliation(s)
| | - Aaron G Schultz
- School of Life and Environmental Sciences, Deakin University, Locked Bag 20000, Geelong, VIC 3220, Australia
| | - Jonathan M Wilson
- Department of Biology, Wilfrid Laurier University, Waterloo, ON, Canada N2L 3C5
| | - Yuhe He
- Department of Biological Sciences, University of Alberta, Edmonton, AB, Canada T6G 2E9
| | - Garett J P Allen
- Department of Biological Sciences, University of Manitoba, Winnipeg, MB, Canada R3T2N2
| | - Greg G Goss
- Department of Biological Sciences, University of Alberta, Edmonton, AB, Canada T6G 2E9
| | - Dirk Weihrauch
- Department of Biological Sciences, University of Manitoba, Winnipeg, MB, Canada R3T2N2
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Physiological and behavioral flexibility to an acute CO 2 challenge, within and between genotypes in rainbow trout. Comp Biochem Physiol A Mol Integr Physiol 2017; 209:25-33. [PMID: 28396262 DOI: 10.1016/j.cbpa.2017.04.002] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2016] [Revised: 03/21/2017] [Accepted: 04/03/2017] [Indexed: 11/23/2022]
Abstract
Adaptive capacities, governing the ability of animals to cope with an environmental stressor, have been demonstrated to be strongly dependent upon genetic factors. Two isogenic lines of rainbow trout, previously described for their sensitivity and resilience to an acute confinement challenge, were used in the present study to investigate whether adaptive capacities remain consistent when fish are exposed to a different type of challenge. For this purpose, the effects of a 4-hour hypercapnia (CO2 increase) challenge at concentrations relevant in aquaculture conditions are described for the two isogenic lines. Oxygen consumption, cortisol release, group dispersion and group swimming activity were measured before, during and after the challenge. Sensitivity and resilience for each measure were extracted from temporal responses and analyzed using multivariate statistics. The two fish lines displayed significant differences in their cortisol response, translating differences in the stress axis sensitivity to the stressor. On the contrary, both lines showed, for other measures, similar temporal patterns across the study. Notable within line variability in the stress response was observed, despite identical genome between fish. The results are discussed in the context of animal robustness.
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36
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Allmon EB, Esbaugh AJ. Carbon dioxide induced plasticity of branchial acid-base pathways in an estuarine teleost. Sci Rep 2017; 7:45680. [PMID: 28378831 PMCID: PMC5381225 DOI: 10.1038/srep45680] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2016] [Accepted: 03/02/2017] [Indexed: 12/21/2022] Open
Abstract
Anthropogenic CO2 is expected to drive ocean pCO2 above 1,000 μatm by 2100 – inducing respiratory acidosis in fish that must be corrected through branchial ion transport. This study examined the time course and plasticity of branchial metabolic compensation in response to varying levels of CO2 in an estuarine fish, the red drum, which regularly encounters elevated CO2 and may therefore have intrinsic resilience. Under control conditions fish exhibited net base excretion; however, CO2 exposure resulted in a dose dependent increase in acid excretion during the initial 2 h. This returned to baseline levels during the second 2 h interval for exposures up to 5,000 μatm, but remained elevated for exposures above 15,000 μatm. Plasticity was assessed via gene expression in three CO2 treatments: environmentally realistic 1,000 and 6,000 μatm exposures, and a proof-of-principle 30,000 μatm exposure. Few differences were observed at 1,000 or 6,000 μatm; however, 30,000 μatm stimulated widespread up-regulation. Translocation of V-type ATPase after 1 h of exposure to 30,000 μatm was also assessed; however, no evidence of translocation was found. These results indicate that red drum can quickly compensate to environmentally relevant acid-base disturbances using baseline cellular machinery, yet are capable of plasticity in response to extreme acid-base challenges.
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Affiliation(s)
- Elizabeth B Allmon
- University of Texas at Austin, University of Texas Marine Science Institute, Port Aransas, TX 78373, USA
| | - Andrew J Esbaugh
- University of Texas at Austin, University of Texas Marine Science Institute, Port Aransas, TX 78373, USA
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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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Wright PA, Wood CM, Hiroi J, Wilson JM. (Uncommon) Mechanisms of Branchial Ammonia Excretion in the Common Carp (Cyprinus carpio) in Response to Environmentally Induced Metabolic Acidosis. Physiol Biochem Zool 2016; 89:26-40. [PMID: 27082522 DOI: 10.1086/683990] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Freshwater fishes generally increase ammonia excretion in acidic waters. The new model of ammonia transport in freshwater fish involves an association between the Rhesus (Rh) protein Rhcg-b, the Na(+)/H(+) exchanger (NHE), and a suite of other membrane transporters. We tested the hypothesis that Rhcg-b and NHE3 together play a critical role in branchial ammonia excretion in common carp (Cyprinus carpio) chronically exposed to a low-pH environment. Carp were exposed to three sequential environmental treatments-control pH 7.6 water (24 h), pH 4.0 water (72 h), and recovery pH 7.6 water (24 h)-or in a separate series were simply exposed to either control (72 h) or pH 4.0 (72 h) water. Branchial ammonia excretion was increased by ∼2.5-fold in the acid compared with the control period, despite the absence of an increase in the plasma-to-water partial pressure NH3 gradient. Alanine aminotransferase activity was higher in the gills of fish exposed to pH 4 versus control water, suggesting that ammonia may be generated in gill tissue. Gill Rhcg-b and NHE3b messenger RNA levels were significantly elevated in acid-treated relative to control fish, but at the protein level Rhcg-b decreased (30%) and NHE3b increased (2-fold) in response to water of pH 4.0. Using immunofluorescence microscopy, NHE3b and Rhcg-b were found to be colocalized to ionocytes along the interlamellar space of the filament of control fish. After 72 h of acid exposure, Rhcg-b staining almost disappeared from this region, and NHE3b was more prominent along the lamellae. We propose that ammoniagenesis within the gill tissue itself is responsible for the higher rates of branchial ammonia excretion during chronic metabolic acidosis. Unexpectedly, gill Rhcg-b does not appear to be important in gill ammonia transport in low-pH water, but the strong induction of NHE3b suggests that some NH4(+) may be eliminated directly in exchange for Na(+). These findings contrast with previous studies in larval zebrafish (Danio rerio) and medaka (Oryzias latipes), underlining the importance of species comparisons.
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Boyle D, Blair SD, Chamot D, Goss GG. Characterization of developmental Na(+) uptake in rainbow trout larvae supports a significant role for Nhe3b. Comp Biochem Physiol A Mol Integr Physiol 2016; 201:30-36. [PMID: 27350321 DOI: 10.1016/j.cbpa.2016.06.027] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2016] [Revised: 06/22/2016] [Accepted: 06/22/2016] [Indexed: 11/26/2022]
Abstract
Developing freshwater fish must compensate for the loss of ions, including sodium (Na(+)), to the environment. In this study, we used a radiotracer flux approach and pharmacological inhibitors to investigate the role of sodium/hydrogen exchange proteins (Nhe) in Na(+) uptake in rainbow trout (Oncorhynchus mykiss) reared from fertilization in soft water (0.1mM Na(+)). For comparison, a second group of embryos/larvae reared in hard water (2.2mM Na(+), higher pH and [Ca(2+)]) were also included in the experiment but were fluxed in soft water, only. Unidirectional rates of Na(+) uptake increased throughout development and were significantly higher in embryos/larvae reared in soft water. However, the mechanisms of Na(+) uptake in both groups of larvae were not significantly different, either in larvae immediately post-hatch or later in development: the broad spectrum Na(+) channel blocker amiloride inhibited 85-90% of uptake and the Nhe-inhibitor EIPA also caused near maximal inhibitions of Na(+) uptake. These data indicated Na(+) uptake was Nhe-mediated in soft water. A role of Nhe3b (but not Nhe2 or Nhe3a) in Na(+) uptake in soft water was also supported through gene expression analyses: expression of nhe3b increased throughout development in whole embryos/larvae in both groups and was significantly higher in those reared in soft water. This pattern of expression correlated well with measurements of Na(+) uptake. Together these data indicate that in part, rainbow trout embryos/larvae reared in low Na(+) soft water maintained Na(+) homeostasis by an EIPA sensitive component of Na(+) uptake, and support a primary role for Nhe3b.
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Affiliation(s)
- David Boyle
- Department of Biological Sciences, University of Alberta, Edmonton, Alberta, T6G 2E9, Canada
| | - Salvatore D Blair
- Department of Biological Sciences, University of Alberta, Edmonton, Alberta, T6G 2E9, Canada
| | - Danuta Chamot
- Department of Biological Sciences, University of Alberta, Edmonton, Alberta, T6G 2E9, Canada
| | - Greg G Goss
- Department of Biological Sciences, University of Alberta, Edmonton, Alberta, T6G 2E9, Canada.
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Bollinger RJ, Madsen SS, Bossus MC, Tipsmark CK. Does Japanese medaka (Oryzias latipes) exhibit a gill Na(+)/K(+)-ATPase isoform switch during salinity change? J Comp Physiol B 2016; 186:485-501. [PMID: 26920794 DOI: 10.1007/s00360-016-0972-6] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2015] [Revised: 02/02/2016] [Accepted: 02/12/2016] [Indexed: 12/12/2022]
Abstract
Some euryhaline teleosts exhibit a switch in gill Na(+)/K(+)-ATPase (Nka) α isoform when moving between fresh water (FW) and seawater (SW). The present study tested the hypothesis that a similar mechanism is present in Japanese medaka and whether salinity affects ouabain, Mg(2+), Na(+) and K(+) affinity of the gill enzyme. Phylogenetic analysis classified six separate medaka Nka α isoforms (α1a, α1b, α1c, α2, α3a and α3b). Medaka acclimated long-term (>30 days) to either FW or SW had similar gill expression of α1c, α2, α3a and α3b, while both α1a and α1b were elevated in SW. Since a potential isoform shift may rely on early changes in transcript abundance, we conducted two short-term (1-3 days) salinity transfer experiments. FW to SW acclimation induced an elevation of α1b and α1a after 1 and 3 days. SW to FW acclimation reduced α1b after 3 days with no other α isoforms affected. To verify that the responses were typical, additional transport proteins were examined. Gill ncc and nhe3 expression were elevated in FW, while cftr and nkcc1a were up-regulated in SW. This is in accordance with putative roles in ion-uptake and secretion. SW-acclimated medaka had higher gill Nka V max and lower apparent K m for Na(+) compared to FW fish, while apparent affinities for K(+), Mg(2+) and ouabain were unchanged. The present study showed that the Japanese medaka does not exhibit a salinity-induced α isoform switch and therefore suggests that Na(+) affinity changes involve altered posttranslational modification or intermolecular interactions.
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Affiliation(s)
- Rebecca J Bollinger
- Department of Biological Sciences, University of Arkansas, SCEN 601, Fayetteville, AR, 72701, USA
| | - Steffen S Madsen
- Department of Biological Sciences, University of Arkansas, SCEN 601, Fayetteville, AR, 72701, USA
- Department of Biology, University of Southern Denmark, Campusvej 55, 5230, Odense M, Denmark
| | - Maryline C Bossus
- Department of Biological Sciences, University of Arkansas, SCEN 601, Fayetteville, AR, 72701, USA
| | - Christian K Tipsmark
- Department of Biological Sciences, University of Arkansas, SCEN 601, Fayetteville, AR, 72701, USA.
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Lin CH, Hu HJ, Hwang PP. Cortisol regulates sodium homeostasis by stimulating the transcription of sodium-chloride transporter (NCC) in zebrafish (Danio rerio). Mol Cell Endocrinol 2016; 422:93-102. [PMID: 26678829 DOI: 10.1016/j.mce.2015.12.001] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/28/2015] [Revised: 11/16/2015] [Accepted: 12/01/2015] [Indexed: 12/28/2022]
Abstract
In mammals, sodium/hydrogen exchanger (NHE) and sodium-chloride cotransporter (NCC) are expressed in renal tubules, and exhibit functional redundancy and mutual compensation in Na(+) uptake. In teleosts, the gills of the adult and skin of the embryonic stage function as external kidneys, and ionocytes are responsible for ionoregulation in these tissues. NHE- and NCC-expressing ionocytes mutually cooperate to adjust Na(+) uptake, which is analogous to the activity of the mammalian kidney. Cortisol is a hormone that controls Na(+) uptake through regulating NCC expression and activity in mammals; however, cortisol-mediated control of NCC expression is little understood in non-mammalian vertebrates, such as teleosts. It is essential for our understanding of the evolution of such regulation to determine whether cortisol has a conserved effect on NCC in vertebrates. In the present study, we treated zebrafish embryos with low Na(+) medium (LNa, 0.04 mM Na(+)) for 3 d to stimulate the mRNA expression of nhe3b, ncc, and cyp11b1 (a cortisol-synthesis enzyme) and whole body cortisol level. Exogenous cortisol treatment (20 mg/l, 3 d) resulted in an elevation of whole-body Na(+) content, ncc expression, and the density of ncc-expressing cells in zebrafish larvae. In loss-of-function experiments, microinjection of glucocorticoid receptor (gr) morpholino (MO) suppressed sodium content, ncc expression, and the density of ncc-expressing cells, but injection of mr MO had no such effects. In addition, exogenous cortisol treatment and gr MO injection also altered ncc expression and the density of ncc-expressing cells in gcm2 morphant larvae. Taken together, cortisol and GR appear to regulate Na(+) absorption through stimulating ncc expression and the differentiation of ncc-expressing ionocytes, providing new insights into the actions of cortisol on Na(+) uptake.
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Affiliation(s)
- Chia-Hao Lin
- Institute of Cellular and Organismic Biology, Academia Sinica, Taipei 115, Taiwan; National Institute for Basic Biology, National Institutes of Natural Sciences, Okazaki, Aichi 444-8787, Japan
| | - Huei-Jyun Hu
- Institute of Cellular and Organismic Biology, Academia Sinica, Taipei 115, Taiwan
| | - Pung-Pung Hwang
- Institute of Cellular and Organismic Biology, Academia Sinica, Taipei 115, Taiwan.
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Zimmer AM, Wilson JM, Wright PA, Hiroi J, Wood CM. Different mechanisms of Na+ uptake and ammonia excretion by the gill and yolk sac epithelium of early life stage rainbow trout. J Exp Biol 2016; 220:775-786. [DOI: 10.1242/jeb.148429] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2016] [Accepted: 12/07/2016] [Indexed: 12/30/2022]
Abstract
In rainbow trout, the dominant site of Na+ uptake (JNain) and ammonia excretion (Jamm) shifts from the skin to the gills over development. Post-hatch (PH; 7 days post-hatch) larvae utilize the yolk sac skin for physiological exchange, whereas by complete yolk sac absorption (CYA; 30 days post-hatch), the gill is the dominant site. At the gills, JNain and Jamm occur via loose Na+/NH4+ exchange, but this exchange has not been examined in the skin of larval trout. Based on previous work, we hypothesized that, contrary to the gill model, JNain by the yolk sac skin of PH trout occurs independently of Jamm. Following a 12-h exposure to high environmental ammonia (HEA; 0.5 mmol l−1 NH4HCO3; [Na+]=600 µmol l−1; pH=8), Jamm by the gills of CYA trout and the yolk sac skin of PH larvae, which were isolated using divided chambers, increased significantly. However, this was coupled to an increase in JNain across the gills only, supporting our hypothesis. Moreover, gene expression of proteins involved in JNain (Na+/H+-exchanger-2 (NHE2) and H+-ATPase) increased in response to HEA only in the CYA gills. We further identified expression of the apical Rhesus (Rh) proteins Rhcg2 in putative pavement cells and Rhcg1 (co-localized with apical NHE2 and NHE3b and Na+/K+-ATPase) in putative peanut lectin agglutinin-positive (PNA+) ionocytes in gill sections. Similar Na+/K+-ATPase-positive cells expressing Rhcg1 and NHE3b, but not NHE2, were identified in the yolk sac epithelium. Overall, our findings suggest that the mechanisms of JNain and Jamm by the dominant exchange epithelium at two distinct stages of early development are fundamentally different.
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Affiliation(s)
- Alex M. Zimmer
- Department of Biology, University of Ottawa, Ottawa, ON, Canada K1N 6N57
- Department of Biology, Wilfrid Laurier University, ON, Canada N2L 3C5
- Department of Zoology, University of British Columbia, Vancouver, BC, Canada V6T 1Z4
| | | | - Patricia A. Wright
- Department of Anatomy, St Marianna University School of Medicine, Miyamae, Kawasaki 216-8511, Japan
| | - Junya Hiroi
- Department of Integrative Biology, University of Guelph, Guelph, ON, Canada N1G 2W1
| | - Chris M. Wood
- Department of Zoology, University of British Columbia, Vancouver, BC, Canada V6T 1Z4
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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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Guffey SC, Fliegel L, Goss GG. Cloning and characterization of Na(+)/H(+) Exchanger isoforms NHE2 and NHE3 from the gill of Pacific dogfish Squalus suckleyi. Comp Biochem Physiol B Biochem Mol Biol 2015; 188:46-53. [PMID: 26112825 DOI: 10.1016/j.cbpb.2015.06.003] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2015] [Revised: 06/16/2015] [Accepted: 06/17/2015] [Indexed: 01/26/2023]
Abstract
Na(+)/H(+) Exchanger (NHE) proteins mediate cellular and systemic homeostasis of sodium and acid and may be the major sodium uptake method for fishes. We cloned and sequenced NHE2 and NHE3 from the gill of the North Pacific Spiny Dogfish shark Squalus suckleyi and expressed them in functional form in NHE-deficient (AP-1) cell lines. Estimated IC50 for inhibition of NHE activity by amiloride and EIPA were 55 μmol l(-1) and 4.8 μmol l(-1), respectively, for NHE2 and 9 μmol l(-1) and 24 μmol l(-1), respectively, for NHE3. Phenamil at 100 μmol l(-1) caused less than 16% inhibition of activity for each isoform. Although the IC50 are similar for the two isoforms, dfNHE2 is less sensitive than human NHE2 to inhibition by amiloride and EIPA, while dfNHE3 is more sensitive than human NHE3. These IC50 estimates should be considered when selecting inhibitor doses for fishes and for reinterpretation of previous studies that use these pharmacological agents.
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Affiliation(s)
- Samuel C Guffey
- Department of Biological Sciences, Z512 Biological Sciences Bldg, University of Alberta, Edmonton, AB T6G 2E9, Canada; Bamfield Marine Sciences Centre, 100 Pachena Road, Bamfield, BC V0R 1B0, Canada.
| | - Larry Fliegel
- Department of Biochemistry, 347 Medical Sciences Bldg, University of Alberta, Edmonton, AB T6G 2H7, Canada.
| | - Greg G Goss
- Department of Biological Sciences, Z512 Biological Sciences Bldg, University of Alberta, Edmonton, AB T6G 2E9, Canada; Bamfield Marine Sciences Centre, 100 Pachena Road, Bamfield, BC V0R 1B0, Canada.
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Lawrence MJ, Wright PA, Wood CM. Physiological and molecular responses of the goldfish (Carassius auratus) kidney to metabolic acidosis, and potential mechanisms of renal ammonia transport. ACTA ACUST UNITED AC 2015; 218:2124-35. [PMID: 25987732 DOI: 10.1242/jeb.117689] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2015] [Accepted: 05/05/2015] [Indexed: 01/20/2023]
Abstract
Relative to the gills, the mechanisms by which the kidney contributes to ammonia and acid-base homeostasis in fish are poorly understood. Goldfish were exposed to a low pH environment (pH 4.0, 48 h), which induced a characteristic metabolic acidosis and an increase in total plasma [ammonia] but reduced plasma ammonia partial pressure (PNH3). In the kidney tissue, total ammonia, lactate and intracellular pH remained unchanged. The urinary excretion rate of net base under control conditions changed to net acid excretion under low pH, with contributions from both the NH4 (+) (∼30%) and titratable acidity minus bicarbonate (∼70%; TA-HCO3 (-)) components. Inorganic phosphate (Pi), urea and Na(+) excretion rates were also elevated while Cl(-) excretion rates were unchanged. Renal alanine aminotransferase activity increased under acidosis. The increase in renal ammonia excretion was due to significant increases in both the glomerular filtration and the tubular secretion rates of ammonia, with the latter accounting for ∼75% of the increase. There was also a 3.5-fold increase in the mRNA expression of renal Rhcg-b (Rhcg1) mRNA. There was no relationship between ammonia secretion and Na(+) reabsorption. These data indicate that increased renal ammonia secretion during acidosis is probably mediated through Rhesus (Rh) glycoproteins and occurs independently of Na(+) transport, in contrast to branchial and epidermal models of Na(+)-dependent ammonia transport in freshwater fish. Rather, we propose a model of parallel H(+)/NH3 transport as the primary mechanism of renal tubular ammonia secretion that is dependent on renal amino acid catabolism.
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Affiliation(s)
- Michael J Lawrence
- Department of Biology, McMaster University, Hamilton, ON, Canada L8S 4K1 Department of Biology, Carleton University, Ottawa, ON, Canada K1S 5B6
| | - Patricia A Wright
- Department of Integrative Biology, University of Guelph, Guelph, ON, Canada N1G 2W1
| | - Chris M Wood
- Department of Biology, McMaster University, Hamilton, ON, Canada L8S 4K1 Department of Zoology, University of British Columbia, Vancouver, BC, Canada V6T 1Z4
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Watson CJ, Nordi WM, Esbaugh AJ. Osmoregulation and branchial plasticity after acute freshwater transfer in red drum, Sciaenops ocellatus. Comp Biochem Physiol A Mol Integr Physiol 2014; 178:82-9. [PMID: 25152533 DOI: 10.1016/j.cbpa.2014.08.008] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2014] [Revised: 07/21/2014] [Accepted: 08/13/2014] [Indexed: 11/27/2022]
Abstract
Red drum, Sciaenops ocellatus, is an estuarine-dependent fish species commonly found in the Gulf of Mexico and along the coast of the southeastern United States. This economically important species has demonstrated freshwater tolerance; however, the physiological mechanisms and costs related to freshwater exposure remain poorly understood. The current study therefore investigated the physiological response of red drum using an acute freshwater transfer protocol. Plasma osmolality, Cl⁻, Mg²⁺ and Ca²⁺ were all significantly reduced by 24h post-transfer; Cl⁻ and Mg²⁺ recovered to control levels by 7days post-transfer. No effect of transfer was observed on muscle water content; however, muscle Cl⁻ was significantly reduced. Interestingly, plasma and muscle Na⁺ content was unaffected by freshwater transfer. Intestinal fluid was absent by 24h post-transfer indicating cessation of drinking. Branchial gene expression analysis showed that both CFTR and NKCC1 exhibited significant down-regulation at 8 and 24h post-transfer, respectively, although transfer had no impact on NHE2, NHE3 or Na⁺, K⁺ ATPase (NKA) activity. These general findings are supported by immunohistochemical analysis, which revealed no apparent NKCC containing cells in the gills at 7days post transfer while NKA cells localization was unaffected. The results of the current study suggest that red drum can effectively regulate Na⁺ balance upon freshwater exposure using already present Na⁺ uptake pathways while also down-regulating ion excretion mechanisms.
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Affiliation(s)
| | - Wiolene M Nordi
- University of Texas Marine Science Institute, Austin, TX 78373, USA
| | - Andrew J Esbaugh
- University of Texas Marine Science Institute, Austin, TX 78373, USA.
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Takei Y, Hiroi J, Takahashi H, Sakamoto T. Diverse mechanisms for body fluid regulation in teleost fishes. Am J Physiol Regul Integr Comp Physiol 2014; 307:R778-92. [PMID: 24965789 DOI: 10.1152/ajpregu.00104.2014] [Citation(s) in RCA: 87] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Teleost fishes are the major group of ray-finned fishes and represent more than one-half of the total number of vertebrate species. They have experienced in their evolution an additional third-round whole genome duplication just after the divergence of their lineage, which endowed them with an extra adaptability to invade various aquatic habitats. Thus their physiology is also extremely diverse compared with other vertebrate groups as exemplified by the many patterns of body fluid regulation or osmoregulation. The key osmoregulatory organ for teleosts, whose body fluid composition is similar to mammals, is the gill, where ions are absorbed from or excreted into surrounding waters of various salinities against concentration gradients. It has been shown that the underlying molecular physiology of gill ionocytes responsible for ion regulation is highly variable among species. This variability is also seen in the endocrine control of osmoregulation where some hormones have distinct effects on body fluid regulation in different teleost species. A typical example is atrial natriuretic peptide (ANP); ANP is secreted in response to increased blood volume and acts on various osmoregulatory organs to restore volume in rainbow trout as it does in mammals, but it is secreted in response to increased plasma osmolality, and specifically decreases NaCl, and not water, in the body of eels. The distinct actions of other osmoregulatory hormones such as growth hormone, prolactin, angiotensin II, and vasotocin among teleost species are also evident. We hypothesized that such diversity of ionocytes and hormone actions among species stems from their intrinsic differences in body fluid regulation that originated from their native habitats, either fresh water or seawater. In this review, we summarized remarkable differences in body fluid regulation and its endocrine control among teleost species, although the number of species is still limited to substantiate the hypothesis.
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Affiliation(s)
- Yoshio Takei
- Laboratory of Physiology, Atmosphere and Ocean Research Institute, The University of Tokyo, Kashiwa, Chiba, Japan;
| | - Junya Hiroi
- Department of Anatomy, St. Marianna University School of Medicine, Kawasaki, Kanagawa, Japan; and
| | - Hideya Takahashi
- Ushimado Marine Institute (UMI), Faculty of Science, Okayama University, Setouchi, Okayama, Japan
| | - Tatsuya Sakamoto
- Ushimado Marine Institute (UMI), Faculty of Science, Okayama University, Setouchi, Okayama, Japan
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Dymowska AK, Schultz AG, Blair SD, Chamot D, Goss GG. Acid-sensing ion channels are involved in epithelial Na+ uptake in the rainbow trout Oncorhynchus mykiss. Am J Physiol Cell Physiol 2014; 307:C255-65. [PMID: 24898589 DOI: 10.1152/ajpcell.00398.2013] [Citation(s) in RCA: 58] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
A role for acid-sensing ion channels (ASICs) to serve as epithelial channels for Na(+) uptake by the gill of freshwater rainbow trout was investigated. We found that the ASIC inhibitors 4',6-diamidino-2-phenylindole and diminazene decreased Na(+) uptake in adult rainbow trout in a dose-dependent manner, with IC50 values of 0.12 and 0.96 μM, respectively. Furthermore, we cloned the trout ASIC1 and ASIC4 homologs and demonstrated that they are expressed differentially in the tissues of the rainbow trout, including gills and isolated mitochondrion-rich cells. Immunohistochemical analysis using custom-made anti-zASIC4.2 antibody and the Na(+)-K(+)-ATPase (α5-subunit) antibody demonstrated that the trout ASIC localizes to Na(+)/K(+)-ATPase-rich cells in the gill. Moreover, three-dimensional rendering of confocal micrographs demonstrated that ASIC is found in the apical region of mitochondrion-rich cells. We present a revised model whereby ASIC4 is proposed as one mechanism for Na(+) uptake from dilute freshwater in the gill of rainbow trout.
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Affiliation(s)
- Agnieszka K Dymowska
- Department of Biological Sciences, University of Alberta, Edmonton, Alberta, Canada
| | - Aaron G Schultz
- Department of Biological Sciences, University of Alberta, Edmonton, Alberta, Canada
| | - Salvatore D Blair
- Department of Biological Sciences, University of Alberta, Edmonton, Alberta, Canada
| | - Danuta Chamot
- Department of Biological Sciences, University of Alberta, Edmonton, Alberta, Canada
| | - Greg G Goss
- Department of Biological Sciences, University of Alberta, Edmonton, Alberta, Canada
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Larsen EH, Deaton LE, Onken H, O'Donnell M, Grosell M, Dantzler WH, Weihrauch D. Osmoregulation and Excretion. Compr Physiol 2014; 4:405-573. [DOI: 10.1002/cphy.c130004] [Citation(s) in RCA: 127] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
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Ito Y, Kato A, Hirata T, Hirose S, Romero MF. Na+/H+ and Na+/NH+4 activities of zebrafish NHE3b expressed in Xenopus oocytes. Am J Physiol Regul Integr Comp Physiol 2014; 306:R315-27. [PMID: 24401990 PMCID: PMC3949079 DOI: 10.1152/ajpregu.00363.2013] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2013] [Accepted: 01/05/2014] [Indexed: 01/14/2023]
Abstract
Zebrafish Na(+)/H(+) exchanger 3b (zNHE3b) is highly expressed in the apical membrane of ionocytes where Na(+) is absorbed from ion-poor fresh water against a concentration gradient. Much in vivo data indicated that zNHE3b is involved in Na(+) absorption but not leakage. However, zNHE3b-mediated Na(+) absorption has not been thermodynamically explained, and zNHE3b activity has not been measured. To address this issue, we overexpressed zNHE3b in Xenopus oocytes and characterized its activity by electrophysiology. Exposure of zNHE3b oocytes to Na(+)-free media resulted in significant decrease in intracellular pH (pH(i)) and intracellular Na(+) activity (aNa(i)). aNa(i) increased significantly when the cytoplasm was acidified by media containing CO₂-HCO₃(-) or butyrate. Activity of zNHE3b was inhibited by amiloride or 5-ethylisopropyl amiloride (EIPA). Although the activity was accompanied by a large hyperpolarization of ∼50 mV, voltage-clamp experiments showed that Na(+)/H(+) exchange activity of zNHE3b is electroneutral. Exposure of zNHE3b oocytes to medium containing NH₃/NH₄(+) resulted in significant decreases in pH(i) and aNa(i) and significant increase in intracellular NH₄(+) activity, indicating that zNHE3b mediates the Na(+)/NH₄(+) exchange. In low-Na(+) (0.5 mM) media, zNHE3b oocytes maintained aNa(i) of 1.3 mM, and Na(+)-influx was observed when pHi was decreased by media containing CO₂-HCO₃(-) or butyrate. These results provide thermodynamic evidence that zNHE3b mediates Na(+) absorption from ion-poor fresh water by its Na(+)/H(+) and Na(+)/NH₄(+) exchange activities.
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Affiliation(s)
- Yusuke Ito
- Department of Biological Sciences, Tokyo Institute of Technology, Yokohama, Japan; and
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