1
|
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.
Collapse
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.
| |
Collapse
|
2
|
Harter TS, Dichiera AM, Esbaugh AJ. The physiological significance of plasma-accessible carbonic anhydrase in the respiratory systems of fishes. J Comp Physiol B 2024:10.1007/s00360-024-01562-4. [PMID: 38842596 DOI: 10.1007/s00360-024-01562-4] [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: 11/30/2023] [Revised: 04/26/2024] [Accepted: 05/13/2024] [Indexed: 06/07/2024]
Abstract
Carbonic anhydrase (CA) activity is ubiquitously found in all vertebrate species, tissues and cellular compartments. Most species have plasma-accessible CA (paCA) isoforms at the respiratory surfaces, where the enzyme catalyzes the conversion of plasma bicarbonate to carbon dioxide (CO2) that can be excreted by diffusion. A notable exception are the teleost fishes that appear to lack paCA at their gills. The present review: (i) recapitulates the significance of CA activity and distribution in vertebrates; (ii) summarizes the current evidence for the presence or absence of paCA at the gills of fishes, from the basal cyclostomes to the derived teleosts and extremophiles such as the Antarctic icefishes; (iii) explores the contribution of paCA to organismal CO2 excretion in fishes; and (iv) the functional significance of its absence at the gills, for the specialized system of O2 transport in most teleosts; (v) outlines the multiplicity and isoform distribution of membrane-associated CAs in fishes and methodologies to determine their plasma-accessible orientation; and (vi) sketches a tentative time line for the evolutionary dynamics of branchial paCA distribution in the major groups of fishes. Finally, this review highlights current gaps in the knowledge on branchial paCA function and provides recommendations for future work.
Collapse
Affiliation(s)
- Till S Harter
- Department of Biology, McMaster University, Hamilton, ON, L8S 4K1, Canada.
| | - Angelina M Dichiera
- College of William and Mary, Virginia Institute of Marine Science, Gloucester Point, VA, 23062, USA
| | - Andrew J Esbaugh
- Marine Science Institute, University of Texas at Austin, Port Aransas, TX, 78373, USA
| |
Collapse
|
3
|
Nelson C, Standen EM, Allen PJ, Brauner CJ. An investigation of gill and blood carbonic anhydrase characteristics in three basal actinopterygian species: alligator gar (Atractosteus spatula), white sturgeon (Acipenser transmontanus) and Senegal bichir (Polypterus senegalus). J Comp Physiol B 2024; 194:155-166. [PMID: 38459993 DOI: 10.1007/s00360-024-01539-3] [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: 08/29/2023] [Revised: 12/22/2023] [Accepted: 01/19/2024] [Indexed: 03/11/2024]
Abstract
Many teleosts possess a unique set of respiratory characteristics allowing enhanced oxygen unloading to the tissues during stress. This system comprises three major components: highly pH sensitive haemoglobins (large Bohr and Root effects), rapid red blood cell (RBC) intracellular pH (pHi) protection, and a heterogeneous distribution of membrane-bound plasma-accessible carbonic anhydrase (paCA; absence in the gills). The first two components have received considerable research effort; however, the evolutionary loss of branchial paCA has received little attention. In the current study, we investigated the availability of branchial membrane-bound CA, along with several other CA-related characteristics in species belonging to three basal actinopterygian groups: the Lepisosteiformes, Acipenseriformes and Polypteriformes to assess the earlier hypothesis that Root effect haemoglobins constrain branchial paCA availability. We present the first evidence suggesting branchial membrane-bound CA presence in a basal actinopterygian species: the Senegal bichir (Polypterus senegalus) and show that like the teleosts, white sturgeon (Acipenser transmontanus) and alligator gar (Atractosteus spatula) do not possess branchial membrane-bound CA. We discuss the varying respiratory strategies for these species and propose that branchial paCA may have been lost much earlier than previously thought, likely in relation to the changes in haemoglobin buffer capacity associated with the increasing magnitude of the Bohr effect. The findings described here represent an important advancement in our understanding of the evolution of the unique system of enhanced oxygen unloading thought to be present in most teleosts, a group that encompasses half of all vertebrates.
Collapse
Affiliation(s)
| | | | - Peter J Allen
- Mississippi State University, Mississippi, 39762, USA
| | - Colin J Brauner
- University of British Columbia, Vancouver, BC, V6T 1Z4, Canada
| |
Collapse
|
4
|
Takvam M, Wood CM, Kryvi H, Nilsen TO. Role of the kidneys in acid-base regulation and ammonia excretion in freshwater and seawater fish: implications for nephrocalcinosis. Front Physiol 2023; 14:1226068. [PMID: 37457024 PMCID: PMC10339814 DOI: 10.3389/fphys.2023.1226068] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2023] [Accepted: 06/12/2023] [Indexed: 07/18/2023] Open
Abstract
Maintaining normal pH levels in the body fluids is essential for homeostasis and represents one of the most tightly regulated physiological processes among vertebrates. Fish are generally ammoniotelic and inhabit diverse aquatic environments that present many respiratory, acidifying, alkalinizing, ionic and osmotic stressors to which they are able to adapt. They have evolved flexible strategies for the regulation of acid-base equivalents (H+, NH4 +, OH- and HCO3 -), ammonia and phosphate to cope with these stressors. The gills are the main regulatory organ, while the kidneys play an important, often overlooked accessory role in acid-base regulation. Here we outline the kidneys role in regulation of acid-base equivalents and two of the key 'urinary buffers', ammonia and phosphate, by integrating known aspects of renal physiology with recent advances in the molecular and cellular physiology of membrane transport systems in the teleost kidneys. The renal transporters (NHE3, NBC1, AE1, SLC26A6) and enzymes (V-type H+ATPase, CAc, CA IV, ammoniagenic enzymes) involved in H+ secretion, bicarbonate reabsorption, and the net excretion of acidic and basic equivalents, ammonia, and inorganic phosphate are addressed. The role of sodium-phosphate cotransporter (Slc34a2b) and rhesus (Rh) glycoproteins (ammonia channels) in conjunction with apical V-type H+ ATPase and NHE3 exchangers in these processes are also explored. Nephrocalcinosis is an inflammation-like disorder due to the precipitation of calcareous material in the kidneys, and is listed as one of the most prevalent pathologies in land-based production of salmonids in recirculating aquaculture systems. The causative links underlying the pathogenesis and etiology of nephrocalcinosis in teleosts is speculative at best, but acid-base perturbation is probably a central pathophysiological cause. Relevant risk factors associated with nephrocalcinosis are hypercapnia and hyperoxia in the culture water. These raise internal CO2 levels in the fish, triggering complex branchial and renal acid-base compensations which may promote formation of kidney stones. However, increased salt loads through the rearing water and the feed may increase the prevalence of nephrocalcinosis. An increased understanding of the kidneys role in acid-base and ion regulation and how this relates to renal diseases such as nephrocalcinosis will have applied relevance for the biologist and aquaculturist alike.
Collapse
Affiliation(s)
- Marius Takvam
- Department of Biological Sciences, University of Bergen, Bergen, Norway
| | - Chris M. Wood
- Department of Zoology, University of British Columbia, Vancouver, BC, Canada
| | - H. Kryvi
- Department of Biological Sciences, University of Bergen, Bergen, Norway
| | - Tom O. Nilsen
- Department of Biological Sciences, University of Bergen, Bergen, Norway
| |
Collapse
|
5
|
Carlos dos Reis D, Dastoor P, Santos AK, Sumigray K, Ameen NA. CFTR high expresser cells in cystic fibrosis and intestinal diseases. Heliyon 2023; 9:e14568. [PMID: 36967909 PMCID: PMC10031467 DOI: 10.1016/j.heliyon.2023.e14568] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2022] [Revised: 03/02/2023] [Accepted: 03/09/2023] [Indexed: 03/16/2023] Open
Abstract
Cystic Fibrosis Transmembrane Conductance Regulator (CFTR), the Cl-/HCO3 - channel implicated in Cystic Fibrosis, is critical to the pathophysiology of many gastrointestinal diseases. Defects in CFTR lead to intestinal dysfunction, malabsorption, obstruction, infection, inflammation, and cancer that increases morbidity and reduces quality of life. This review will focus on CFTR in the intestine and the implications of the subpopulation of CFTR High Expresser Cells (CHEs) in Cystic Fibrosis (CF), intestinal physiology and pathophysiology of intestinal diseases.
Collapse
Affiliation(s)
- Diego Carlos dos Reis
- Department of Pediatrics/Gastroenterology and Hepatology, Yale School of Medicine, CT, 06510, USA
| | - Parinaz Dastoor
- Department of Pediatrics/Gastroenterology and Hepatology, Yale School of Medicine, CT, 06510, USA
| | - Anderson Kenedy Santos
- Department of Pediatrics/Gastroenterology and Hepatology, Yale School of Medicine, CT, 06510, USA
- Department of Genetics, Yale School of Medicine, New Haven, CT, 06510, USA
| | - Kaelyn Sumigray
- Department of Genetics, Yale School of Medicine, New Haven, CT, 06510, USA
- Yale Stem Cell Center, Yale School of Medicine, New Haven, CT, 06510, USA
- Yale Cancer Center, Yale School of Medicine, New Haven, CT, 06510, USA
| | - Nadia A. Ameen
- Department of Pediatrics/Gastroenterology and Hepatology, Yale School of Medicine, CT, 06510, USA
- Department of Cellular and Molecular Physiology, Yale School of Medicine, New Haven, CT06510, USA
- Corresponding author. Department of Pediatrics/Gastroenterology and Hepatology, Yale School of Medicine, CT, 06510, USA.
| |
Collapse
|
6
|
Dichiera AM, De Anda V, Gilmour KM, Baker BJ, Esbaugh AJ. Functional divergence of teleost carbonic anhydrase 4. Comp Biochem Physiol A Mol Integr Physiol 2023; 277:111368. [PMID: 36642322 DOI: 10.1016/j.cbpa.2023.111368] [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: 10/14/2022] [Revised: 12/14/2022] [Accepted: 01/10/2023] [Indexed: 01/15/2023]
Abstract
The functional role of membrane-bound carbonic anhydrases (CAs) has been of keen interest in the past decade, and in particular, studies have linked CA in red muscle, heart, and eye to enhanced tissue oxygen extraction in bony fishes (teleosts). However, the number of purported membrane-bound CA isoforms in teleosts, combined with the imperfect system of CA isoform nomenclature, present roadblocks for ascribing physiological functions to particular CA isoforms across different teleost lineages. Here we developed an organizational framework for membrane-bound CAs in teleosts, providing the latest phylogenetic analysis of extant CA4 and CA4-like isoforms. Our data confirm that there are three distinct isoforms of CA4 (a, b, and c) that are conserved across major teleost lineages, with the exception of CA4c gene being lost in salmonids. Tissue distribution analyses suggest CA4a functions in oxygen delivery across teleost lineages, while CA4b may be specialized for renal acid-base balance and ion regulation. This work provides an important foundation for researchers to elucidate the functional significance of CA4 isoforms in fishes.
Collapse
Affiliation(s)
- Angelina M Dichiera
- Department of Zoology, The University of British Columbia, Vancouver, BC V6T 1Z4, Canada.
| | - Valerie De Anda
- Marine Science Institute, The University of Texas at Austin, Port Aransas, TX 78373, USA. https://twitter.com/val_deanda
| | | | - Brett J Baker
- Marine Science Institute, The University of Texas at Austin, Port Aransas, TX 78373, USA; Department of Integrative Biology, The University of Texas at Austin, Austin, TX 78712, USA. https://twitter.com/archaeal
| | - Andrew J Esbaugh
- Marine Science Institute, The University of Texas at Austin, Port Aransas, TX 78373, USA
| |
Collapse
|
7
|
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.
Collapse
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
| | | |
Collapse
|
8
|
Aspatwar A, Syrjänen L, Parkkila S. Roles of Carbonic Anhydrases and Carbonic Anhydrase Related Proteins in Zebrafish. Int J Mol Sci 2022; 23:ijms23084342. [PMID: 35457162 PMCID: PMC9032886 DOI: 10.3390/ijms23084342] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2022] [Revised: 04/07/2022] [Accepted: 04/12/2022] [Indexed: 11/25/2022] Open
Abstract
During recent decades, zebrafish (Danio rerio) have become one of the most important model organisms in which to study different physiological and biological phenomena. The research field of carbonic anhydrases (CAs) and carbonic anhydrase related proteins (CARPs) is not an exception to this. The best-known function of CAs is the regulation of acid–base balance. However, studies performed with zebrafish, among others, have revealed important roles for these proteins in many other physiological processes, some of which had not yet been predicted in the light of previous studies and suggestions. Examples include roles in zebrafish pigmentation as well as motor coordination. Disruption of the function of these proteins may generate lethal outcomes. In this review, we summarize the current knowledge of CA-related studies performed in zebrafish from 1993–2021 that was obtained from PubMed search.
Collapse
|
9
|
Aspatwar A, Tolvanen MEE, Barker H, Syrjänen L, Valanne S, Purmonen S, Waheed A, Sly WS, Parkkila S. Carbonic Anhydrases in Metazoan Model Organisms: Molecules, Mechanisms, and Physiology. Physiol Rev 2022; 102:1327-1383. [PMID: 35166161 DOI: 10.1152/physrev.00018.2021] [Citation(s) in RCA: 34] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
During the past three decades, mice, zebrafish, fruit flies, and Caenorhabditis elegans have been the primary model organisms used for the study of various biological phenomena. These models have also been adopted and developed to investigate the physiological roles of carbonic anhydrases (CAs) and carbonic anhydrase-related proteins (CARPs). These proteins belong to eight CA families and are identified by Greek letters: α, β, γ, δ, ζ, η, θ, and ι. Studies using model organisms have focused on two CA families, α-CAs and β-CAs, which are expressed in both prokaryotic and eukaryotic organisms with species-specific distribution patterns and unique functions. This review covers the biological roles of CAs and CARPs in light of investigations performed in model organisms. Functional studies demonstrate that CAs are not only linked to the regulation of pH homeostasis, the classical role of CAs but also contribute to a plethora of previously undescribed functions.
Collapse
Affiliation(s)
- Ashok Aspatwar
- Faculty of Medicine and Health Technology, Tampere University, Tampere, Finland
| | | | - Harlan Barker
- Faculty of Medicine and Health Technology, Tampere University, Tampere, Finland.,Fimlab Ltd and TAYS Cancer Centre, Tampere University Hospital, Tampere, Finland
| | - Leo Syrjänen
- Faculty of Medicine and Health Technology, Tampere University, Tampere, Finland.,Department of Otorhinolaryngology, Tampere University Hospital, Tampere, Finland
| | - Susanna Valanne
- Faculty of Medicine and Health Technology, Tampere University, Tampere, Finland
| | - Sami Purmonen
- Faculty of Medicine and Health Technology, Tampere University, Tampere, Finland
| | - Abdul Waheed
- Department of Biochemistry and Molecular Biology, Edward A. Doisy Research Center, Saint Louis University School of Medicine, St. Louis, MO, United States
| | - William S Sly
- Department of Biochemistry and Molecular Biology, Edward A. Doisy Research Center, Saint Louis University School of Medicine, St. Louis, MO, United States
| | - Seppo Parkkila
- Faculty of Medicine and Health Technology, Tampere University, Tampere, Finland.,Fimlab Ltd and TAYS Cancer Centre, Tampere University Hospital, Tampere, Finland
| |
Collapse
|
10
|
Matsumoto H, Miyagi H, Nakamura N, Shiga Y, Ohta T, Fujiwara S, Tsuzuki M. Carbonic anhydrase inhibitor induces otic hair cell apoptosis via an intrinsic pathway and ER stress in zebrafish larvae. Toxicol Rep 2021; 8:1937-1947. [PMID: 34926172 PMCID: PMC8648832 DOI: 10.1016/j.toxrep.2021.11.018] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2021] [Revised: 11/22/2021] [Accepted: 11/24/2021] [Indexed: 11/28/2022] Open
Abstract
CA inhibitor EZA causes lateral line organ death in zebrafish larvae. Neuromast hair cells are especially sensitive to EZA during embryo development. EZA induces apoptosis in otic hair cells via an intrinsic pathway and ER stress.
Carbonic anhydrase (CA) catalyzes reversible hydration of CO2 to HCO3− to mediate pH and ion homeostasis. Some chemical pollutants have been reported to have inhibitory effects on fish CA. In this study, we investigated effects of a CA inhibitor ethoxyzolamide (EZA) on neuromasts development during zebrafish embryogenesis, since embryogenesis in aquatic organisms can be particularly sensitive to water pollution. EZA caused alteration of pH and calcium concentration and production of reactive oxygen species (ROS) in larvae, and induced apoptosis in hair cells especially in the otic neuromast, in which CA2 was distributed on the body surface. mRNA levels of apoptotic genes and caspase activities were increased by EZA, whereas anti-oxidants and apoptotic inhibitors, Bax, NF-κB, and p53 inhibitors significantly relieved the induction of hair cell death. Also, mRNA levels of Bip and CHOP, which are induced in response to ER stress, were upregulated by EZA, suggesting that EZA induces otic hair cell apoptosis via the intrinsic mitochondrial pathway and ER stress. Our results demonstrated an essential role of CA in neuromast development via maintenance of ion transport and pH, and that the CA, which is directly exposed to the ambient water, shows marked sensitivity to EZA.
Collapse
Affiliation(s)
- Hiroko Matsumoto
- School of Life Sciences, Tokyo University of Pharmacy and Life Sciences, Horinouchi, Hachioji, Tokyo, 192-0392, Japan
| | - Hisako Miyagi
- Department of Life Science and Technology, Tokyo Institute of Technology, 4259-B13 Nagatsuta-cho, Midori-ku, Yokohama, 226-8501, Japan
| | - Nobuhiro Nakamura
- Department of Life Science and Technology, Tokyo Institute of Technology, 4259-B13 Nagatsuta-cho, Midori-ku, Yokohama, 226-8501, Japan
| | - Yasuhiro Shiga
- School of Life Sciences, Tokyo University of Pharmacy and Life Sciences, Horinouchi, Hachioji, Tokyo, 192-0392, Japan
| | - Toshihiro Ohta
- School of Life Sciences, Tokyo University of Pharmacy and Life Sciences, Horinouchi, Hachioji, Tokyo, 192-0392, Japan
| | - Shoko Fujiwara
- School of Life Sciences, Tokyo University of Pharmacy and Life Sciences, Horinouchi, Hachioji, Tokyo, 192-0392, Japan
- Corresponding author at: School of Life Sciences, Tokyo University of Pharmacy and Life Sciences, 1432-1 Horinouchi, Hachioji, Tokyo, 192-0392, Japan.
| | - Mikio Tsuzuki
- School of Life Sciences, Tokyo University of Pharmacy and Life Sciences, Horinouchi, Hachioji, Tokyo, 192-0392, Japan
| |
Collapse
|
11
|
Aranda-Morales SA, Peña-Marín ES, Jiménez-Martínez LD, Martínez-Burguete T, Martínez-Bautista G, Álvarez-Villagómez CS, De la Rosa-García S, Camarillo-Coop S, Martínez-García R, Guzmán-Villanueva LT, Álvarez-González CA. Expression of ion transport proteins and routine metabolism in juveniles of tropical gar (Atractosteus tropicus) exposed to ammonia. Comp Biochem Physiol C Toxicol Pharmacol 2021; 250:109166. [PMID: 34411697 DOI: 10.1016/j.cbpc.2021.109166] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/08/2021] [Revised: 07/13/2021] [Accepted: 08/06/2021] [Indexed: 12/14/2022]
Abstract
Tropical gar (Atractosteus tropicus) thrives in aquatic habitats with high levels of total nitrogen (TAN) and unionized ammonia (NH3). However, the tolerance of TAN and NH3, the excretion mechanisms involved, and the effects of these chemicals on routine metabolism are still unknown. Therefore, our objectives were to assess the acute toxicity of TAN and NH3 in A. tropicus juveniles after a 96-h exposure (LC50-96 h) to NH4Cl and after chronic exposure to two concentrations (15% and 30% of LC50-96 h TAN) for 12 days, as well as to evaluate the transcriptional effects associated with Rhesus proteins (rhag, rhbg, rhcg) and ion transporters (NHE, NKA, NKCC, and CFTR) in gills and skin; and to determine the effects of TAN and NH3 on routine metabolism through oxygen consumption (μM g-1 h-1) and gill ventilation frequency (beats min-1). LC50-96 h values were 100.20 ± 11.21 mg/L for TAN and 3.756 ± 0.259 mg/L for NH3. The genes encoding Rhesus proteins and ion transporters in gills and skin showed a differential expression according to TAN concentrations and exposure time. Oxygen consumption on day 12 showed significant differences between treatments with 15% and 30% TAN. Gill ventilation frequency on day 12 was higher in fish exposed to 30% TAN. In conclusion, A. tropicus juveniles are highly tolerant to TAN, showing upregulation of the genes involved in TAN excretion through gills and skin, which affects routine oxygen consumption and energetic cost. These findings are relevant for understanding adaptations in the physiological response of a tropical ancestral air-breathing fish.
Collapse
Affiliation(s)
- Sonia A Aranda-Morales
- División Académica de Ciencias Biológicas, Universidad Juárez Autónoma de Tabasco, Carretera Villahermosa-Cárdenas Km 0.5, C.P.86139 Villahermosa, Tabasco, Mexico
| | - Emyr S Peña-Marín
- División Académica de Ciencias Biológicas, Universidad Juárez Autónoma de Tabasco, Carretera Villahermosa-Cárdenas Km 0.5, C.P.86139 Villahermosa, Tabasco, Mexico; Consejo Nacional de Ciencia y Tecnología, Av. Insurgentes Sur 1582, Col. Crédito Constructor, Del. Benito Juárez C.P. 03940, Mexico
| | - Luis D Jiménez-Martínez
- División Académica Multidisciplinaria de Jalpa de Méndez, Universidad Juárez Autónoma de Tabasco, Carretera Nacajuca-Jalpa de Méndez R/a Rivera Alta, C.P. 86200 Jalpa de Méndez, Tabasco, Mexico
| | - Talhia Martínez-Burguete
- División Académica de Ciencias Biológicas, Universidad Juárez Autónoma de Tabasco, Carretera Villahermosa-Cárdenas Km 0.5, C.P.86139 Villahermosa, Tabasco, Mexico
| | - Gil Martínez-Bautista
- División Académica de Ciencias Biológicas, Universidad Juárez Autónoma de Tabasco, Carretera Villahermosa-Cárdenas Km 0.5, C.P.86139 Villahermosa, Tabasco, Mexico
| | - Carina S Álvarez-Villagómez
- División Académica de Ciencias Biológicas, Universidad Juárez Autónoma de Tabasco, Carretera Villahermosa-Cárdenas Km 0.5, C.P.86139 Villahermosa, Tabasco, Mexico
| | - Susana De la Rosa-García
- División Académica de Ciencias Biológicas, Universidad Juárez Autónoma de Tabasco, Carretera Villahermosa-Cárdenas Km 0.5, C.P.86139 Villahermosa, Tabasco, Mexico
| | - Susana Camarillo-Coop
- División Académica de Ciencias Biológicas, Universidad Juárez Autónoma de Tabasco, Carretera Villahermosa-Cárdenas Km 0.5, C.P.86139 Villahermosa, Tabasco, Mexico
| | - Rafael Martínez-García
- División Académica de Ciencias Biológicas, Universidad Juárez Autónoma de Tabasco, Carretera Villahermosa-Cárdenas Km 0.5, C.P.86139 Villahermosa, Tabasco, Mexico
| | - Laura T Guzmán-Villanueva
- Consejo Nacional de Ciencia y Tecnología, Av. Insurgentes Sur 1582, Col. Crédito Constructor, Del. Benito Juárez C.P. 03940, Mexico; Centro de Investigaciones Biológicas del Noroeste S.C., Av. Instituto Politécnico Nacional 195. Col. Playa Palo de Santa Rita Sur, 23096 La Paz, Baja California Sur, Mexico
| | - Carlos A Álvarez-González
- División Académica de Ciencias Biológicas, Universidad Juárez Autónoma de Tabasco, Carretera Villahermosa-Cárdenas Km 0.5, C.P.86139 Villahermosa, Tabasco, Mexico.
| |
Collapse
|
12
|
Wen J, Mercado GP, Volland A, Doden HL, Lickwar CR, Crooks T, Kakiyama G, Kelly C, Cocchiaro JL, Ridlon JM, Rawls JF. Fxr signaling and microbial metabolism of bile salts in the zebrafish intestine. SCIENCE ADVANCES 2021; 7:eabg1371. [PMID: 34301599 PMCID: PMC8302129 DOI: 10.1126/sciadv.abg1371] [Citation(s) in RCA: 31] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/13/2020] [Accepted: 06/07/2021] [Indexed: 05/02/2023]
Abstract
Bile salt synthesis, secretion into the intestinal lumen, and resorption in the ileum occur in all vertebrate classes. In mammals, bile salt composition is determined by host and microbial enzymes, affecting signaling through the bile salt-binding transcription factor farnesoid X receptor (Fxr). However, these processes in other vertebrate classes remain poorly understood. We show that key components of hepatic bile salt synthesis and ileal transport pathways are conserved and under control of Fxr in zebrafish. Zebrafish bile salts consist primarily of a C27 bile alcohol and a C24 bile acid that undergo multiple microbial modifications including bile acid deconjugation that augments Fxr activity. Using single-cell RNA sequencing, we provide a cellular atlas of the zebrafish intestinal epithelium and uncover roles for Fxr in transcriptional and differentiation programs in ileal and other cell types. These results establish zebrafish as a nonmammalian vertebrate model for studying bile salt metabolism and Fxr signaling.
Collapse
Affiliation(s)
- Jia Wen
- Department of Molecular Genetics and Microbiology, Duke Microbiome Center, Duke University School of Medicine, Durham, NC, USA
| | - Gilberto Padilla Mercado
- Department of Molecular Genetics and Microbiology, Duke Microbiome Center, Duke University School of Medicine, Durham, NC, USA
| | - Alyssa Volland
- Carl R. Woese Institute for Genomic Biology, University of Illinois at Urbana Champaign, Urbana, IL, USA
| | - Heidi L Doden
- Carl R. Woese Institute for Genomic Biology, University of Illinois at Urbana Champaign, Urbana, IL, USA
- Department of Animal Sciences, University of Illinois at Urbana Champaign, Urbana, IL, USA
| | - Colin R Lickwar
- Department of Molecular Genetics and Microbiology, Duke Microbiome Center, Duke University School of Medicine, Durham, NC, USA
| | - Taylor Crooks
- Carl R. Woese Institute for Genomic Biology, University of Illinois at Urbana Champaign, Urbana, IL, USA
| | - Genta Kakiyama
- Department of Internal Medicine, School of Medicine, Virginia Commonwealth University, Richmond, VA, USA
| | - Cecelia Kelly
- Department of Molecular Genetics and Microbiology, Duke Microbiome Center, Duke University School of Medicine, Durham, NC, USA
| | - Jordan L Cocchiaro
- Department of Molecular Genetics and Microbiology, Duke Microbiome Center, Duke University School of Medicine, Durham, NC, USA
| | - Jason M Ridlon
- Carl R. Woese Institute for Genomic Biology, University of Illinois at Urbana Champaign, Urbana, IL, USA.
- Department of Animal Sciences, University of Illinois at Urbana Champaign, Urbana, IL, USA
- Division of Nutritional Sciences, University of Illinois at Urbana Champaign, Urbana, IL, USA
- Cancer Center of Illinois, Urbana, IL, USA
| | - John F Rawls
- Department of Molecular Genetics and Microbiology, Duke Microbiome Center, Duke University School of Medicine, Durham, NC, USA.
| |
Collapse
|
13
|
Zimmer AM, Mandic M, Yew HM, Kunert E, Pan YK, Ha J, Kwong RWM, Gilmour KM, Perry SF. Use of a carbonic anhydrase Ca17a knockout to investigate mechanisms of ion uptake in zebrafish ( Danio rerio). Am J Physiol Regul Integr Comp Physiol 2021; 320:R55-R68. [PMID: 33085911 DOI: 10.1152/ajpregu.00215.2020] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
In fishes, branchial cytosolic carbonic anhydrase (CA) plays an important role in ion and acid-base regulation. The Ca17a isoform in zebrafish (Danio rerio) is expressed abundantly in Na+-absorbing/H+-secreting H+-ATPase-rich (HR) cells. The present study aimed to identify the role of Ca17a in ion and acid-base regulation across life stages using CRISPR/Cas9 gene editing. However, in preliminary experiments, we established that ca17a knockout is lethal with ca17a-/- mutants exhibiting a significant decrease in survival beginning at ∼12 days postfertilization (dpf) and with no individuals surviving past 19 dpf. Based on these findings, we hypothesized that ca17a-/- mutants would display alterations in ion and acid-base balance and that these physiological disturbances might underlie their early demise. Na+ uptake rates were significantly increased by up to 300% in homozygous mutants compared with wild-type individuals at 4 and 9 dpf; however, whole body Na+ content remained constant. While Cl- uptake was significantly reduced in ca17a-/- mutants, Cl- content was unaffected. Reduction of CA activity by Ca17a morpholino knockdown or ethoxzolamide treatments similarly reduced Cl- uptake, implicating Ca17a in the mechanism of Cl- uptake by larval zebrafish. H+ secretion, O2 consumption, CO2 excretion, and ammonia excretion were generally unaltered in ca17a-/- mutants. In conclusion, while the loss of Ca17a caused marked changes in ion uptake rates, providing strong evidence for a Ca17a-dependent Cl- uptake mechanism, the underlying causes of the lethality of this mutation in zebrafish remain unclear.
Collapse
Affiliation(s)
- Alex M Zimmer
- Department of Biology, University of Ottawa, Ottawa, Ontario, Canada
| | - Milica Mandic
- Department of Biology, University of Ottawa, Ottawa, Ontario, Canada
| | - Hong Meng Yew
- Department of Biology, University of Ottawa, Ottawa, Ontario, Canada
| | - Emma Kunert
- Department of Biology, University of Ottawa, Ottawa, Ontario, Canada
| | - Yihang K Pan
- Department of Biology, University of Ottawa, Ottawa, Ontario, Canada
| | - Jimmy Ha
- Department of Biology, University of Ottawa, Ottawa, Ontario, Canada
| | - Raymond W M Kwong
- Department of Biology, University of Ottawa, Ottawa, Ontario, Canada
| | | | - Steve F Perry
- Department of Biology, University of Ottawa, Ottawa, Ontario, Canada
| |
Collapse
|
14
|
Posavi M, Gulisija D, Munro JB, Silva JC, Lee CE. Rapid evolution of genome-wide gene expression and plasticity during saline to freshwater invasions by the copepod Eurytemora affinis species complex. Mol Ecol 2020; 29:4835-4856. [PMID: 33047351 DOI: 10.1111/mec.15681] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2019] [Revised: 09/18/2020] [Accepted: 10/01/2020] [Indexed: 01/01/2023]
Abstract
Saline migrants into freshwater habitats constitute among the most destructive invaders in aquatic ecosystems throughout the globe. However, the evolutionary and physiological mechanisms underlying such habitat transitions remain poorly understood. To explore the mechanisms of freshwater adaptation and distinguish between adaptive (evolutionary) and acclimatory (plastic) responses to salinity change, we examined genome-wide patterns of gene expression between ancestral saline and derived freshwater populations of the Eurytemora affinis species complex, reared under two different common-garden conditions (0 versus 15 PSU). We found that evolutionary shifts in gene expression (between saline and freshwater inbred lines) showed far greater changes and were more widespread than acclimatory responses to salinity (0 versus 15 PSU). Most notably, 30-40 genes showing evolutionary shifts in gene expression across the salinity boundary were associated with ion transport function, with inorganic cation transmembrane transport forming the largest Gene Ontology category. Of particular interest was the sodium transporter, the Na+ /H+ antiporter (NHA) gene family, which was discovered in animals relatively recently. Thirty key ion regulatory genes, such as NHA paralogue #7, demonstrated concordant evolutionary and plastic shifts in gene expression, suggesting the evolution of ion transporter function and plasticity during rapid invasions into novel salinities. Moreover, freshwater invasions were associated with the evolution of reduced plasticity in the freshwater population, again for the same key ion transporters, consistent with the predicted evolution of canalization following adaptation to stressful conditions. Our results have important implications for understanding evolutionary and physiological mechanisms of range expansions by some of the most widespread invaders in aquatic habitats.
Collapse
Affiliation(s)
- Marijan Posavi
- Department of Integrative Biology, University of Wisconsin, Madison, WI, USA
| | - Davorka Gulisija
- Department of Biology, University of New Mexico, Albuquerque, NM, USA
| | - James B Munro
- Institute for Genome Sciences, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Joana C Silva
- Institute for Genome Sciences, University of Maryland School of Medicine, Baltimore, MD, USA.,Department of Microbiology and Immunology, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Carol Eunmi Lee
- Department of Integrative Biology, University of Wisconsin, Madison, WI, USA
| |
Collapse
|
15
|
Shir-Mohammadi K, Perry SF. Expression of ion transport genes in ionocytes isolated from larval zebrafish ( Danio rerio) exposed to acidic or Na +-deficient water. Am J Physiol Regul Integr Comp Physiol 2020; 319:R412-R427. [PMID: 32755465 DOI: 10.1152/ajpregu.00095.2020] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
In zebrafish (Danio rerio), a specific ionocyte subtype, the H+-ATPase-rich (HR) cell, is presumed to be a significant site of transepithelial Na+ uptake/acid secretion. During acclimation to environments differing in ionic composition or pH, ionic and acid-base regulations are achieved by adjustments to the activity level of HR cell ion transport proteins. In previous studies, the quantitative assessment of mRNA levels for genes involved in ionic and acid-base regulations relied on measurements using homogenates derived from the whole body (larvae) or the gill (adult). Such studies cannot distinguish whether any differences in gene expression arise from adjustments of ionocyte subtype numbers or transcriptional regulation specifically within individual ionocytes. The goal of the present study was to use fluorescence-activated cell sorting to separate the HR cells from other cellular subpopulations to facilitate the measurement of gene expression of HR cell-specific transporters and enzymes from larvae exposed to low pH (pH 4.0) or low Na+ (5 μM) conditions. The data demonstrate that treatment of larvae with acidic water for 4 days postfertilization caused cell-specific increases in H+-ATPase (atp6v1aa), ca17a, ca15a, nhe3b, and rhcgb mRNA in addition to increases in mRNA linked to cell proliferation. In fish exposed to low Na+, expression of nhe3b and rhcgb was increased owing to HR cell-specific regulation and elevated numbers of HR cells. Thus, the results of this study demonstrate that acclimation to low pH or low Na+ environmental conditions is facilitated by HR cell-specific transcriptional control and by HR cell proliferation.
Collapse
Affiliation(s)
| | - S F Perry
- Department of Biology, University of Ottawa, Ontario, Canada
| |
Collapse
|
16
|
Chou CH, Wu CY, Chen CL, Zhou JQ, Kao YC, Chen HY, Lin PC. In vivo monitoring of carbonic anhydrase expression during the growth of larval zebrafish: a new environment-sensitive fluorophore for responsive turn-on fluorescence. Chem Commun (Camb) 2020; 56:11307-11310. [PMID: 32840276 DOI: 10.1039/d0cc03090b] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
This study monitors the dynamic progress of a newly developed background-free, target responsive strategy; 2,3-dihydroquinolin-4-imine (DQI) that can instantly respond to environmental changes with fluorescence enhancement, revealing a comprehensive platform for in vivo fluorescence bioimaging of mebrane-bound carbonic anhydrase II in HeLa cells and its expression during the growth of larval zebrafish.
Collapse
Affiliation(s)
- Chih-Hung Chou
- Department of Chemistry, National Sun Yat-sen University, Kaohsiung 80424, Taiwan.
| | | | | | | | | | | | | |
Collapse
|
17
|
Zimmer AM, Perry SF. The Rhesus glycoprotein Rhcgb is expendable for ammonia excretion and Na + uptake in zebrafish (Danio rerio). Comp Biochem Physiol A Mol Integr Physiol 2020; 247:110722. [PMID: 32437959 DOI: 10.1016/j.cbpa.2020.110722] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2019] [Revised: 05/01/2020] [Accepted: 05/01/2020] [Indexed: 11/27/2022]
Abstract
In zebrafish (Danio rerio), the ammonia-transporting Rhesus glycoprotein Rhcgb is implicated in mechanisms of ammonia excretion and Na+ uptake. In particular, Rhcgb is thought to play an important role in maintaining ammonia excretion in response to alkaline conditions and high external ammonia (HEA) exposure, in addition to facilitating Na+ uptake via a functional metabolon with the Na+/H+-exchanger Nhe3b, specifically under low Na+ conditions. In the present study, we hypothesized that CRISPR/Cas9 knockout of rhcgb would reduce ammonia excretion and Na+ uptake capacity, particularly under the conditions listed above that have elicited increases in Rhcgb-mediated ammonia excretion and/or Na+ uptake. Contrary to this hypothesis, however, larval and juvenile rhcgb knockout (KO) mutants showed no reductions in ammonia excretion or Na+ uptake under any of the conditions tested in our study. In fact, under control conditions, rhcgb KO mutants generally displayed an increase in ammonia excretion, potentially due to increased transcript abundance of another rh gene, rhbg. Under alkaline conditions, rhcgb KO mutants were also able to maintain ammonia excretion, similar to wild-type fish, and stimulation of ammonia excretion after HEA exposure also was not affected by rhcgb KO. Surprisingly, ammonia excretion and Na+ uptake were unaffected by rhcgb or nhe3b KO in juvenile zebrafish acclimated to normal (800 μmol/L) or low (10 μmol/L) Na+ conditions. These results demonstrate that Rhcgb is expendable for ammonia excretion and Na+ uptake in zebrafish, highlighting the plasticity and flexibility of these physiological systems in this species.
Collapse
Affiliation(s)
- Alex M Zimmer
- Department of Biological Sciences, University of Alberta, Edmonton, Alberta, Canada; Department of Biology, University of Ottawa, Ottawa, Ontario, Canada.
| | - Steve F Perry
- Department of Biology, University of Ottawa, Ottawa, Ontario, Canada
| |
Collapse
|
18
|
Eom J, Fehsenfeld S, Wood CM. Is ammonia excretion affected by gill ventilation in the rainbow trout Oncorhynchus mykiss? Respir Physiol Neurobiol 2020; 275:103385. [DOI: 10.1016/j.resp.2020.103385] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2019] [Revised: 12/09/2019] [Accepted: 01/08/2020] [Indexed: 02/08/2023]
|
19
|
Yew HM, Zimmer AM, Perry SF. Assessing intracellular pH regulation in H +-ATPase-rich ionocytes in zebrafish larvae using in vivo ratiometric imaging. J Exp Biol 2020; 223:jeb212928. [PMID: 32029462 DOI: 10.1242/jeb.212928] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2019] [Accepted: 01/28/2020] [Indexed: 12/11/2022]
Abstract
The H+-ATPase-rich (HR) cells of zebrafish larvae are a sub-type of ion-transporting cell located on the yolk sac epithelium that are responsible for Na+ uptake and H+ extrusion. Current models of HR cell ion transport mechanisms in zebrafish larvae are well established, but little is known about the involvement of the various ion transport pathways in regulating intracellular acid-base status. Here, a ratiometric imaging technique was developed and validated to monitor intracellular pH (pHi) continuously in larval zebrafish HR cells in vivo Gene knockdown or CRISPR/Cas9 knockout approaches were used to evaluate the roles of the two principal apical membrane acid excretory pathways, the Na+/H+ exchanger (NHE3b; slc9a3.2) and the H+-ATPase (atpv1aa). Additionally, the role of HR cell cytosolic carbonic anhydrase (CAc) was investigated because of its presumed role in providing H+ for Na+/H+ exchange and H+-ATPase. The temporal pattern and extent of intracellular acidification during exposure of fish to 1% CO2 and the extent of post-CO2 alkalisation were altered markedly in fish experiencing knockdown/knockout of CAc, NHE3b or H+-ATPase. Although there were slight differences among the three knockdown/knockout experiments, the typical response was a greater degree of intracellular acidification during CO2 exposure and a reduced capacity to restore pHi to baseline levels post-hypercapnia. The metabolic alkalosis and subsequent acidification associated with 20 mmol l-1 NH4Cl exposure and its washout were largely unaffected by gene knockdown. Overall, the results suggest markedly different mechanisms of intracellular acid-base regulation in zebrafish HR cells depending on the nature of the acid-base disturbance.
Collapse
Affiliation(s)
- H M Yew
- Department of Biology, University of Ottawa, 30 Marie Curie, Ottawa, ON KIN 6N5, Canada
| | - A M Zimmer
- Department of Biology, University of Ottawa, 30 Marie Curie, Ottawa, ON KIN 6N5, Canada
| | - S F Perry
- Department of Biology, University of Ottawa, 30 Marie Curie, Ottawa, ON KIN 6N5, Canada
| |
Collapse
|
20
|
Chen P, Liu C, Li P, Wang Q, Gao X, Wu H, Huang J. High RhCG expression predicts poor survival and promotes migration and proliferation of gastric cancer via keeping intracellular alkaline. Exp Cell Res 2020; 386:111740. [PMID: 31756312 DOI: 10.1016/j.yexcr.2019.111740] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2019] [Revised: 11/15/2019] [Accepted: 11/18/2019] [Indexed: 11/25/2022]
Abstract
Advanced gastric cancer (GC) is aggressive with a high mortality rate. Rhesus family, C glycoprotein (RhCG) participates in tumor progression in many cancers, however its function in GC is still unknown. Here, we showed that RhCG was overexpressed in GC tissues at mRNA (P = 0.036) and protein levels (P < 0.05) compared with normal tissues. High RhCG level was correlated with poor differentiation (P = 0.037), TNM stage (P < 0.001), high HER-2 level (P = 0.018) and worse prognosis (P < 0.001). Cox proportional hazard model indicated that RhCG level was an independent prognostic biomarker. RhCG knockdown significantly decreased pHi and impeded tumor cellular proliferation, migration and invasion and repressed β-catenin and c-myc expression in GC cells. Moreover, GC cells with high RhCG level had reduced oxaliplatin efficacy suggesting a role for RhCG as a therapeutic target for GC. Our findings revealed a function of RhCG in cancer pathogenesis, invasion and metastasis in human GC. We suggest that RhCG act may as a novel prognostic indicator and a therapeutic target for gastric adenocarcinoma.
Collapse
Affiliation(s)
- Pei Chen
- Department of Clinical Biobank, Affiliated Hospital of Nantong University, Nantong, Jiangsu, 226000, China; Department of Oncology, Medical School of Nantong University, Nantong, Jiangsu, 226000, China
| | - Can Liu
- Department of Oncology, Medical School of Nantong University, Nantong, Jiangsu, 226000, China
| | - Peng Li
- Department of General Surgery, Affiliated Hospital of Nantong University, Nantong, Jiangsu, 226000, China
| | - Qingqing Wang
- Department of General Surgery, Affiliated Hospital of Nantong University, Nantong, Jiangsu, 226000, China
| | - Xiaodong Gao
- Department of General Surgery, Medical School of Nantong University, Nantong, Jiangsu, 226000, China
| | - Han Wu
- Department of General Surgery, Affiliated Hospital of Nantong University, Nantong, Jiangsu, 226000, China.
| | - JianFei Huang
- Department of Clinical Biobank, Affiliated Hospital of Nantong University, Nantong, Jiangsu, 226000, China; Institute of Oncology, Affiliated Hospital of Nantong University, Nantong 226001, Jiangsu, China.
| |
Collapse
|
21
|
Gordon WE, Espinoza JA, Leerberg DM, Yelon D, Hamdoun A. Xenobiotic transporter activity in zebrafish embryo ionocytes. AQUATIC TOXICOLOGY (AMSTERDAM, NETHERLANDS) 2019; 212:88-97. [PMID: 31077970 PMCID: PMC6561644 DOI: 10.1016/j.aquatox.2019.04.013] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/27/2019] [Revised: 04/14/2019] [Accepted: 04/16/2019] [Indexed: 06/09/2023]
Abstract
Ionocytes are specialized cells in the epidermis of embryonic zebrafish (Danio rerio) that play important roles in ion homeostasis and have functional similarities to mammalian renal cells. Here, we examined whether these cells might also share another functional similarity with renal cells, which is the presence of efflux transporter activities useful for elimination of toxic small molecules. Xenobiotic transporters (XTs), including the ATP-Binding Cassette (ABC) family, are a major defense mechanism against diffusible toxic molecules in aquatic embryos, including zebrafish, but their activity in the ionocytes has not previously been studied. Using fluorescent small molecule substrates of XT, we observed that specific populations of ionocytes uptake and efflux fluorescent small molecules in a manner consistent with active transport. We specifically identified a P-gp/ABCB1 inhibitor-sensitive efflux activity in the H+-ATPase-rich (HR) ionocytes, and show that these cells exhibit enriched expression of the ABCB gene, abcb5. The results extend our understanding of the functional significance of zebrafish ionocytes and indicate that these cells could play an important role in protection of the fish embryo from harmful small molecules.
Collapse
Affiliation(s)
- Wei E Gordon
- Marine Biology Research Division, Scripps Institution of Oceanography, University of California, San Diego, La Jolla, CA, USA; Division of Biological Sciences, University of California, San Diego, La Jolla, CA, USA
| | - Jose A Espinoza
- Marine Biology Research Division, Scripps Institution of Oceanography, University of California, San Diego, La Jolla, CA, USA
| | - Dena M Leerberg
- Division of Biological Sciences, University of California, San Diego, La Jolla, CA, USA
| | - Deborah Yelon
- Division of Biological Sciences, University of California, San Diego, La Jolla, CA, USA
| | - Amro Hamdoun
- Marine Biology Research Division, Scripps Institution of Oceanography, University of California, San Diego, La Jolla, CA, USA.
| |
Collapse
|
22
|
Monroe I, Wentworth S, Thede K, Aravindabose V, Garvin J, Packer RK. Activity changes in gill ion transporter enzymes in response to salinity and temperature in fathead minnows (Pimephales promelas). Comp Biochem Physiol A Mol Integr Physiol 2019; 228:29-34. [DOI: 10.1016/j.cbpa.2018.10.018] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2018] [Accepted: 10/21/2018] [Indexed: 02/08/2023]
|
23
|
Zimmer AM, Shir-Mohammadi K, Kwong RWM, Perry SF. Reassessing the contribution of the Na+/H+ exchanger Nhe3b to Na+ uptake in zebrafish (Danio rerio) using CRISPR/Cas9 gene editing. J Exp Biol 2019; 223:jeb.215111. [DOI: 10.1242/jeb.215111] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2019] [Accepted: 12/10/2019] [Indexed: 12/14/2022]
Abstract
Freshwater fishes absorb Na+ from their dilute environment using ion-transporting cells. In larval zebrafish (Danio rerio), Na+ uptake is coordinated by (1) Na+/H+-exchanger 3b (Nhe3b) and (2) H+-ATPase-powered electrogenic uptake in H+-ATPase-rich (HR) cells and by (3) Na+-Cl−-cotransporter (Ncc) expressed in NCC cells. The present study aimed to better understand the roles of these 3 proteins in Na+ uptake by larval zebrafish under ‘normal’ (800 µmol/L) and ‘low’ (10 µmol/L) Na+ conditions. We hypothesized that Na+ uptake would be reduced by CRISPR/Cas9 knockout (KO) of slc9a3.2 (encoding Nhe3b), particularly in low Na+ where Nhe3b is believed to play a dominant role. Contrary to this hypothesis, Na+ uptake was sustained in nhe3b KO larvae under both Na+ conditions, which led to the exploration of whether compensatory regulation of H+-ATPase or Ncc was responsible for maintaining Na+ uptake in nhe3b KO larvae. mRNA expression of the genes encoding H+-ATPase and Ncc were not altered in nhe3b KO. Moreover, morpholino knockdown of H+-ATPase, which significantly reduced H+ flux by HR cells, did not reduce Na+ uptake in nhe3b KO larvae, nor did rearing larvae in chloride-free conditions, thereby eliminating any driving force for Na+-Cl−-cotransport via Ncc. Finally, simultaneously treating nhe3b KO larvae with H+-ATPase morpholino and chloride-free conditions did not reduce Na+ uptake under normal or low Na+. These findings highlight the flexibility of the Na+ uptake system and demonstrate that Nhe3b is expendable to Na+ uptake in zebrafish and that our understanding of Na+ uptake mechanisms in this species is incomplete.
Collapse
Affiliation(s)
- Alex M. Zimmer
- Department of Biology, University of Ottawa, Ottawa, Ontario, Canada
| | | | | | - Steve F. Perry
- Department of Biology, University of Ottawa, Ottawa, Ontario, Canada
| |
Collapse
|
24
|
Physiological protective action of dissolved organic carbon on ion regulation and nitrogenous waste excretion of zebrafish (Danio rerio) exposed to low pH in ion-poor water. J Comp Physiol B 2018; 188:793-807. [DOI: 10.1007/s00360-018-1169-y] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2018] [Revised: 05/29/2018] [Accepted: 06/04/2018] [Indexed: 12/25/2022]
|
25
|
Zimmer AM, Wright PA, Wood CM. Ammonia and urea handling by early life stages of fishes. ACTA ACUST UNITED AC 2018; 220:3843-3855. [PMID: 29093184 DOI: 10.1242/jeb.140210] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Nitrogen metabolism in fishes has been a focus of comparative physiologists for nearly a century. In this Review, we focus specifically on early life stages of fishes, which have received considerable attention in more recent work. Nitrogen metabolism and excretion in early life differs fundamentally from that of juvenile and adult fishes because of (1) the presence of a chorion capsule in embryos that imposes a limitation on effective ammonia excretion, (2) an amino acid-based metabolism that generates a substantial ammonia load, and (3) the lack of a functional gill, which is the primary site of nitrogen excretion in juvenile and adult fishes. Recent findings have shed considerable light on the mechanisms by which these constraints are overcome in early life. Perhaps most importantly, the discovery of Rhesus (Rh) glycoproteins as ammonia transporters and their expression in ion-transporting cells on the skin of larval fishes has transformed our understanding of ammonia excretion by fishes in general. The emergence of larval zebrafish as a model species, together with genetic knockdown techniques, has similarly advanced our understanding of ammonia and urea metabolism and excretion by larval fishes. It has also now been demonstrated that ammonia excretion is one of the primary functions of the developing gill in rainbow trout larvae, leading to new hypotheses regarding the physiological demands driving gill development in larval fishes. Here, we highlight and discuss the dramatic changes in nitrogen handling that occur over early life development in fishes.
Collapse
Affiliation(s)
- Alex M Zimmer
- Department of Biology, University of Ottawa, Ottawa, ON, Canada K1N 6N57
| | - Patricia A Wright
- Department of Integrative Biology, University of Guelph, Guelph, ON, Canada N1G 2W1
| | - Chris M Wood
- Department of Zoology, University of British Columbia, Vancouver, BC, Canada V6T 1Z4.,Department of Biology, McMaster University, Hamilton, ON, Canada L8S 4K1
| |
Collapse
|
26
|
Lewis L, Kwong RWM. Zebrafish as a Model System for Investigating the Compensatory Regulation of Ionic Balance during Metabolic Acidosis. Int J Mol Sci 2018; 19:E1087. [PMID: 29621145 PMCID: PMC5979485 DOI: 10.3390/ijms19041087] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2018] [Revised: 03/25/2018] [Accepted: 04/02/2018] [Indexed: 12/16/2022] Open
Abstract
Zebrafish (Danio rerio) have become an important model for integrative physiological research. Zebrafish inhabit a hypo-osmotic environment; to maintain ionic and acid-base homeostasis, they must actively take up ions and secrete acid to the water. The gills in the adult and the skin at larval stage are the primary sites of ionic regulation in zebrafish. The uptake of ions in zebrafish is mediated by specific ion transporting cells termed ionocytes. Similarly, in mammals, ion reabsorption and acid excretion occur in specific cell types in the terminal region of the renal tubules (distal convoluted tubule and collecting duct). Previous studies have suggested that functional regulation of several ion transporters/channels in the zebrafish ionocytes resembles that in the mammalian renal cells. Additionally, several mechanisms involved in regulating the epithelial ion transport during metabolic acidosis are found to be similar between zebrafish and mammals. In this article, we systemically review the similarities and differences in ionic regulation between zebrafish and mammals during metabolic acidosis. We summarize the available information on the regulation of epithelial ion transporters during acidosis, with a focus on epithelial Na⁺, Cl- and Ca2+ transporters in zebrafish ionocytes and mammalian renal cells. We also discuss the neuroendocrine responses to acid exposure, and their potential role in ionic compensation. Finally, we identify several knowledge gaps that would benefit from further study.
Collapse
Affiliation(s)
- Lletta Lewis
- Department of Biology, York University, Toronto, ON M3J 1P3, Canada.
| | - Raymond W M Kwong
- Department of Biology, York University, Toronto, ON M3J 1P3, Canada.
| |
Collapse
|
27
|
Wood CM, Gonzalez RJ, Ferreira MS, Braz-Mota S, Val AL. The physiology of the Tambaqui (Colossoma macropomum) at pH 8.0. J Comp Physiol B 2017; 188:393-408. [DOI: 10.1007/s00360-017-1137-y] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2017] [Revised: 11/05/2017] [Accepted: 11/17/2017] [Indexed: 12/20/2022]
|
28
|
Chen XL, Zhang B, Chng YR, Ong JLY, Chew SF, Wong WP, Lam SH, Ip YK. Na +/H + Exchanger 3 Is Expressed in Two Distinct Types of Ionocyte, and Probably Augments Ammonia Excretion in One of Them, in the Gills of the Climbing Perch Exposed to Seawater. Front Physiol 2017; 8:880. [PMID: 29209224 PMCID: PMC5701670 DOI: 10.3389/fphys.2017.00880] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2017] [Accepted: 10/18/2017] [Indexed: 01/22/2023] Open
Abstract
The freshwater climbing perch, Anabas testudineus, is an euryhaline teleost and an obligate air-breather with the ability to actively excrete ammonia. Members of the Na+/H+ exchanger (NHE) family help maintain intracellular pH homeostasis and ionic balance through the electroneutral exchange of Na+ and H+. This study aimed to obtain, from the gills of A. testudineus, the full cDNA coding sequence of nhe3, and to determine the effects of exposure to seawater or 100 mmol l-1 of NH4Cl in fresh water on its mRNA and protein expression levels. Efforts were also made to elucidate the type of ionocyte that Nhe3 was associated with in the branchial epithelium of A. testudineus. The transcript level and protein abundance of nhe3/Nhe3 were very low in the gills of freshwater A. testudineus, but they increased significantly in the gills of fish acclimated to seawater. In the gills of fish exposed to seawater, Nhe3 was expressed in two distinct types of seawater-inducible Na+/K+-ATPase (Nka)-immunoreactive ionocytes. In Nkaα1b-immunoreactive ionocytes, Nhe3 had an apical localization. As these ionocytes also expressed apical Rhcg1 and basolateral Rhcg2, which are known to transport ammonia, they probably participated in proton-facilitated ammonia excretion in A. testudineus during seawater acclimation. In Nkaα1c-immunoreactive ionocytes, Nhe3 was atypically expressed in the basolateral membrane, and its physiological function is uncertain. For A. testudineus exposed to NH4Cl in fresh water, the transcript and protein expression levels of nhe3/Nhe3 remained low. In conclusion, the branchial Nhe3 of A. testudineus plays a greater physiological role in passive ammonia transport and acid-base balance during seawater acclimation than in active ammonia excretion during environmental ammonia exposure.
Collapse
Affiliation(s)
- Xiu L. Chen
- Department of Biological Sciences, National University of Singapore, Singapore, Singapore
| | - Biyan Zhang
- Department of Biological Sciences, National University of Singapore, Singapore, Singapore
| | - You R. Chng
- Department of Biological Sciences, National University of Singapore, Singapore, Singapore
| | - Jasmine L. Y. Ong
- Department of Biological Sciences, National University of Singapore, Singapore, Singapore
| | - Shit F. Chew
- Natural Sciences and Science Education, National Institute of Education, Nanyang Technological University, Singapore, Singapore
| | - Wai P. Wong
- Department of Biological Sciences, National University of Singapore, Singapore, Singapore
| | - Siew H. Lam
- Department of Biological Sciences, National University of Singapore, Singapore, Singapore
- NUS Environmental Research Institute, National University of Singapore, Singapore, Singapore
| | - Yuen K. Ip
- Department of Biological Sciences, National University of Singapore, Singapore, Singapore
| |
Collapse
|
29
|
Matsumoto H, Fujiwara S, Miyagi H, Nakamura N, Shiga Y, Ohta T, Tsuzuki M. Carbonic Anhydrase Inhibitors Induce Developmental Toxicity During Zebrafish Embryogenesis, Especially in the Inner Ear. MARINE BIOTECHNOLOGY (NEW YORK, N.Y.) 2017; 19:430-440. [PMID: 28695384 DOI: 10.1007/s10126-017-9763-7] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/11/2016] [Accepted: 06/06/2017] [Indexed: 06/07/2023]
Abstract
In vertebrates, carbonic anhydrases (CAs) play important roles in ion transport and pH regulation in many organs, including the eyes, kidneys, central nervous system, and inner ear. In aquatic organisms, the enzyme is inhibited by various chemicals present in the environment, such as heavy metals, pesticides, and pharmaceuticals. In this study, the effects of CA inhibitors, i.e., sulfonamides [ethoxyzolamide (EZA), acetazolamide (AZA), and dorzolamide (DZA)], on zebrafish embryogenesis were investigated. In embryos treated with the sulfonamides, abnormal development, such as smaller otoliths, an enlarged heart, an irregular pectoral fin, and aberrant swimming behavior, was observed. Especially, the development of otoliths and locomotor activity was severely affected by all the sulfonamides, and EZA was a consistently stronger inhibitor than AZA or DZA. In the embryos treated with EZA, inner ear hair cells containing several CA isoforms, which provide HCO3- to the endolymph for otolith calcification and maintain an appropriate pH there, were affected. Acridine orange/ethidium bromide staining indicated that the hair cell damage in the inner ear and pectral fin is due to apoptosis. Moreover, RNA measurement demonstrated that altered gene expression of cell cycle arrest- and apoptosis-related proteins p53, p21, p27, and Bcl-2 occurred even at 0.08 ppm with which normal development was observed. This finding suggests that a low concentration of EZA may affect embryogenesis via the apoptosis pathway. Thus, our findings demonstrated the importance of potential risk assessment of CA inhibition, especially regarding the formation of otoliths as a one of the most sensitive organs in embryogenesis.
Collapse
Affiliation(s)
- Hiroko Matsumoto
- School of Life Sciences, Tokyo University of Pharmacy and Life Sciences, Horinouchi, Hachioji, Tokyo, 192-0392, Japan
| | - Shoko Fujiwara
- School of Life Sciences, Tokyo University of Pharmacy and Life Sciences, Horinouchi, Hachioji, Tokyo, 192-0392, Japan.
| | - Hisako Miyagi
- Department of Life Science and Technology, Tokyo Institute of Technology, 4259-B13 Nagatsuta-cho, Midori-ku, Yokohama, 226-8501, Japan
| | - Nobuhiro Nakamura
- Department of Life Science and Technology, Tokyo Institute of Technology, 4259-B13 Nagatsuta-cho, Midori-ku, Yokohama, 226-8501, Japan
| | - Yasuhiro Shiga
- School of Life Sciences, Tokyo University of Pharmacy and Life Sciences, Horinouchi, Hachioji, Tokyo, 192-0392, Japan
| | - Toshihiro Ohta
- School of Life Sciences, Tokyo University of Pharmacy and Life Sciences, Horinouchi, Hachioji, Tokyo, 192-0392, Japan
| | - Mikio Tsuzuki
- School of Life Sciences, Tokyo University of Pharmacy and Life Sciences, Horinouchi, Hachioji, Tokyo, 192-0392, Japan
| |
Collapse
|
30
|
Araújo JDA, Ghelfi A, Val AL. Triportheus albus Cope, 1872 in the Blackwater, Clearwater, and Whitewater of the Amazon: A Case of Phenotypic Plasticity? Front Genet 2017; 8:114. [PMID: 28912799 PMCID: PMC5583242 DOI: 10.3389/fgene.2017.00114] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2017] [Accepted: 08/17/2017] [Indexed: 12/15/2022] Open
Abstract
The Amazon basin includes 1000s of bodies of water, that are sorted according to their color in three types: blackwater, clearwater, and whitewater, which significantly differ in terms of their physicochemical parameters. More than 3,000 species of fish live in the rivers of the Amazon, among them, the sardine, Triportheus albus, which is one of the few species that inhabit all three types of water. The purpose of our study was to analyze if the gene expression of T. albus is determined by the different types of water, that is, if the species presents phenotypic plasticity to live in blackwater, clearwater, and whitewater. Gills of T. albus were collected at well-characterized sites for each type of water. Nine cDNA libraries were constructed, three biological replicates of each condition and the RNA was sequenced (RNA-Seq) on the MiSeq® Platform (Illumina®). A total of 51.6 million of paired-end reads, and 285,456 transcripts were assembled. Considering the FDR ≤ 0.05 and fold change ≥ 2, 13,754 differentially expressed genes were detected in the three water types. Two mechanisms related to homeostasis were detected in T. albus that live in blackwater, when compared to the ones in clearwater and whitewater. The acidic blackwater is a challenging environment for many types of aquatic organisms. The first mechanism is related to the decrease in cellular permeability, highlighting the genes coding for claudin proteins, actn4, itgb3b, DSP, Gap junction protein, and Ca2+-ATPase. The second with ionic and acid-base regulation [rhcg1, slc9a6a (NHE), ATP6V0A2, Na+/K+-ATPase, slc26a4 (pedrin) and slc4a4b]. We suggest T. albus is a good species of fish for future studies involving the ionic and acid-base regulation of Amazonian species. We also concluded that, T. albus, shows well defined phenotypic plasticity for each water type in the Amazon basin.
Collapse
Affiliation(s)
- José D A Araújo
- Laboratory of Ecophysiology and Molecular Evolution, National Institute of Amazonian ResearchManaus, Brazil.,Federal University of AmazonasManaus, Brazil
| | | | - Adalberto L Val
- Laboratory of Ecophysiology and Molecular Evolution, National Institute of Amazonian ResearchManaus, Brazil
| |
Collapse
|
31
|
Wang X, Wang M, Jia Z, Qiu L, Wang L, Zhang A, Song L. A Carbonic Anhydrase Serves as an Important Acid-Base Regulator in Pacific Oyster Crassostrea gigas Exposed to Elevated CO 2: Implication for Physiological Responses of Mollusk to Ocean Acidification. MARINE BIOTECHNOLOGY (NEW YORK, N.Y.) 2017; 19:22-35. [PMID: 28204970 DOI: 10.1007/s10126-017-9734-z] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/11/2016] [Accepted: 12/24/2016] [Indexed: 06/06/2023]
Abstract
Carbonic anhydrases (CAs) have been demonstrated to play an important role in acid-base regulation in vertebrates. However, the classification and modulatory function of CAs in marine invertebrates, especially their responses to ocean acidification remain largely unknown. Here, a cytosolic α-CA (designated as CgCAII-1) was characterized from Pacific oyster Crassostrea gigas and its molecular activities against CO2 exposure were investigated. CgCAII-1 possessed a conserved CA catalytic domain, with high similarity to invertebrate cytoplasmic or mitochondrial α-CAs. Recombinant CgCAII-1 could convert CO2 to HCO3- with calculated activity as 0.54 × 103 U/mg, which could be inhibited by acetazolamide (AZ). The mRNA transcripts of CgCAII-1 in muscle, mantle, hepatopancreas, gill, and hemocytes increased significantly after exposure to elevated CO2. CgCAII-1 could interact with the hemocyte membrane proteins and the distribution of CgCAII-1 protein became more concentrated and dense in gill and mantle under CO2 exposure. The intracellular pH (pHi) of hemocytes under CO2 exposure increased significantly (p < 0.05) and CA inhibition reduced the pHi value. Besides, there was no increase in CA activity in gill and mantle after CO2 exposure. The impact of CO2 exposure on CA activity coupled with the mRNA expression level and protein translocation of CgCAII-1 provided evidences that CgCAII-1 could respond to ocean acidification and participate in acid-base regulation. Such cytoplasmic CA-based physiological regulation mechanism might explain other physiological responses of marine organisms to OA.
Collapse
Affiliation(s)
- Xiudan Wang
- Key Laboratory of Experimental Marine Biology, Institute of Oceanology, Chinese Academy of Sciences, Qingdao, 266071, China
- University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Mengqiang Wang
- Key Laboratory of Experimental Marine Biology, Institute of Oceanology, Chinese Academy of Sciences, Qingdao, 266071, China
| | - Zhihao Jia
- Key Laboratory of Experimental Marine Biology, Institute of Oceanology, Chinese Academy of Sciences, Qingdao, 266071, China
- University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Limei Qiu
- Key Laboratory of Experimental Marine Biology, Institute of Oceanology, Chinese Academy of Sciences, Qingdao, 266071, China
| | - Lingling Wang
- Liaoning Key Laboratory of Marine Animal Immunology and Disease Control, Dalian Ocean University, Dalian, 116023, China
| | - Anguo Zhang
- Liaoning Key Laboratory of Marine Animal Immunology and Disease Control, Dalian Ocean University, Dalian, 116023, China
| | - Linsheng Song
- Liaoning Key Laboratory of Marine Animal Immunology and Disease Control, Dalian Ocean University, Dalian, 116023, China.
| |
Collapse
|
32
|
Harter TS, Brauner CJ. The O 2 and CO 2 Transport System in Teleosts and the Specialized Mechanisms That Enhance Hb–O 2 Unloading to Tissues. ACTA ACUST UNITED AC 2017. [DOI: 10.1016/bs.fp.2017.09.001] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
|
33
|
Kersten S, Arjona FJ. Ion transport in the zebrafish kidney from a human disease angle: possibilities, considerations, and future perspectives. Am J Physiol Renal Physiol 2017; 312:F172-F189. [DOI: 10.1152/ajprenal.00425.2016] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2016] [Revised: 11/11/2016] [Accepted: 11/14/2016] [Indexed: 12/31/2022] Open
Abstract
Unique experimental advantages, such as its embryonic/larval transparency, high-throughput nature, and ease of genetic modification, underpin the rapid emergence of the zebrafish ( Danio rerio) as a preeminent model in biomedical research. Particularly in the field of nephrology, the zebrafish provides a promising model for studying the physiological implications of human solute transport processes along consecutive nephron segments. However, although the zebrafish might be considered a valuable model for numerous renal ion transport diseases and functional studies of many channels and transporters, not all human renal electrolyte transport mechanisms and human diseases can be modeled in the zebrafish. With this review, we explore the ontogeny of zebrafish renal ion transport, its nephron structure and function, and thereby demonstrate the clinical translational value of this model. By critical assessment of genomic and amino acid conservation of human proteins involved in renal ion handling (channels, transporters, and claudins), kidney and nephron segment conservation, and renal electrolyte transport physiology in the zebrafish, we provide researchers and nephrologists with an indication of the possibilities and considerations of the zebrafish as a model for human renal ion transport. Combined with advanced techniques envisioned for the future, implementation of the zebrafish might expand beyond unraveling pathophysiological mechanisms that underlie distinct genetic or environmentally, i.e., pharmacological and lifestyle, induced renal transport deficits. Specifically, the ease of drug administration and the exploitation of improved genetic approaches might argue for the adoption of the zebrafish as a model for preclinical personalized medicine for distinct renal diseases and renal electrolyte transport proteins.
Collapse
Affiliation(s)
- Simone Kersten
- Department of Physiology, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, The Netherlands; and
- Nephrology Division, Department of Medicine, Massachusetts General Hospital, Charlestown, Massachusetts
| | - Francisco J. Arjona
- Department of Physiology, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, The Netherlands; and
| |
Collapse
|
34
|
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: 14] [Impact Index Per Article: 1.8] [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.
Collapse
|
35
|
Dennenmoser S, Vamosi SM, Nolte AW, Rogers SM. Adaptive genomic divergence under high gene flow between freshwater and brackish-water ecotypes of prickly sculpin (Cottus asper) revealed by Pool-Seq. Mol Ecol 2016; 26:25-42. [DOI: 10.1111/mec.13805] [Citation(s) in RCA: 52] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2016] [Revised: 07/29/2016] [Accepted: 08/11/2016] [Indexed: 12/19/2022]
Affiliation(s)
- Stefan Dennenmoser
- Max-Planck Institute for Evolutionary Biology; August Thienemann Strasse 2 24306 Plön Germany
- Department of Biological Sciences; University of Calgary; 2500 University Drive NW Calgary AB Canada T2N 1N4
| | - Steven M. Vamosi
- Department of Biological Sciences; University of Calgary; 2500 University Drive NW Calgary AB Canada T2N 1N4
| | - Arne W. Nolte
- Max-Planck Institute for Evolutionary Biology; August Thienemann Strasse 2 24306 Plön Germany
- Institute for Biology; Carl von Ossietzky University Oldenburg; Carl von Ossietzky Str. 9-11 26111 Oldenburg Germany
| | - Sean M. Rogers
- Department of Biological Sciences; University of Calgary; 2500 University Drive NW Calgary AB Canada T2N 1N4
| |
Collapse
|
36
|
Bucking C. A broader look at ammonia production, excretion, and transport in fish: a review of impacts of feeding and the environment. J Comp Physiol B 2016; 187:1-18. [PMID: 27522221 DOI: 10.1007/s00360-016-1026-9] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2016] [Revised: 07/22/2016] [Accepted: 07/29/2016] [Indexed: 12/23/2022]
Abstract
For nearly a century, researchers have studied ammonia production and excretion in teleost fish. Stemming from past investigations a body of knowledge now exists on various aspects including biochemical mechanisms of ammonia formation and specific routes and tissues used for ammonia transport, culminating in a current detailed theoretical model of branchial transport, including the molecular identities of the moieties involved. However, typical studies examining ammonia balance use routine laboratory conditions and fasted fish. While avoiding additional variables that influence nitrogen balance, these studies are arguably idealistic and do not reflect the natural variety of conditions that fish encounter. Further studies have revealed the impacts of extrinsic factors (e.g. salinity, pH, temperature) on ammonia handling in fasted fish whereas others have explored intrinsic factors, such as life history and developmental impacts. One routine challenge for ammonia balance that fish encounter is feeding and digestion. Fortunately, many new studies have revealed the impact of feeding and digestion on several aspects of ammonia balance; from production to excretion and to transport, and several have done so incorporating supplemental extrinsic and/or intrinsic factors. Together, these complex studies reveal realistic responses to multifactorial challenges encountered by animals in the wild and begin to provide a holistic view of ammonia balance in freshwater teleost fish.
Collapse
Affiliation(s)
- Carol Bucking
- Department of Biology, Farquharson Life Science Building, York University, Toronto, ON, M3J 1P3, Canada.
| |
Collapse
|
37
|
Liu ST, Horng JL, Chen PY, Hwang PP, Lin LY. Salt secretion is linked to acid-base regulation of ionocytes in seawater-acclimated medaka: new insights into the salt-secreting mechanism. Sci Rep 2016; 6:31433. [PMID: 27511107 PMCID: PMC4980601 DOI: 10.1038/srep31433] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2015] [Accepted: 07/12/2016] [Indexed: 11/25/2022] Open
Abstract
Ionocytes in the skin and gills of seawater (SW) teleosts are responsible for both salt and acid secretion. However, the mechanism through which ionocytes secrete acid is still unclear. Here, we hypothesized that apical Na+/H+ exchangers (NHE2/3), carbonic anhydrase (CA2-like), and basolateral HCO3−/Cl− exchanger (AE1) are involved in acid secretion. In addition, the hypothesized involvement of basolateral AE1 suggested that acid secretion may be linked to Cl− secretion by ionocytes. The scanning ion-selective electrode technique (SIET) was used to measure H+ and Cl− secretion by ionocytes in the skin of medaka larvae acclimated to SW. Treatment with inhibitors of NHE, CA, and AE suppressed both H+ and Cl− secretion by ionocytes. Short-term exposure to hypercapnic SW stimulated both H+ and Cl− secretion. mRNA of CA2-like and AE1 were localized to ionocytes in the skin. Branchial mRNA levels of NKCC1a, CA2-like, and AE1a increased together with the salinity to which fish were acclimated. In addition, both AE1a and AE1b mRNA increased in fish acclimated to acidified (pH 7) SW; NKCC1a mRNA increased in fish acclimated to pH 9 SW. This study reveals the mechanism of H+ secretion by ionocytes, and refines our understanding of the well-established mechanism of Cl− secretion by ionocytes of SW fish.
Collapse
Affiliation(s)
- Sian-Tai Liu
- Department of Life Science, National Taiwan Normal University, Taipei, Taiwan
| | - Jiun-Lin Horng
- Department of Anatomy and Cell Biology, Taipei Medical University, Taipei, Taiwan
| | - Po-Yen Chen
- Department of Life Science, National Taiwan Normal University, Taipei, Taiwan
| | - Pung-Pung Hwang
- Institute of Cellular and Organismic Biology, Academia Sinica, Taipei, Taiwan
| | - Li-Yih Lin
- Department of Life Science, National Taiwan Normal University, Taipei, Taiwan
| |
Collapse
|
38
|
Duarte RM, Smith DS, Val AL, Wood CM. Dissolved organic carbon from the upper Rio Negro protects zebrafish (Danio rerio) against ionoregulatory disturbances caused by low pH exposure. Sci Rep 2016; 6:20377. [PMID: 26853589 PMCID: PMC4745052 DOI: 10.1038/srep20377] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2015] [Accepted: 11/25/2015] [Indexed: 01/24/2023] Open
Abstract
The so-called "blackwaters" of the Amazonian Rio Negro are rich in highly coloured dissolved organic carbon (DOC), but ion-poor and very acidic, conditions that would cause fatal ionoregulatory failure in most fish. However these blackwaters support 8% of the world's ichthyofauna. We tested the hypothesis that native DOC provides protection against ionoregulatory dysfunction in this extreme environment. DOCs were isolated by reverse-osmosis from two Rio Negro sites. Physico-chemical characterization clearly indicated a terrigenous origin, with a high proportion of hydroxyl and phenolic sites, high chemical reactivity to protons, and unusual proteinaceous fluorescence. When tested using zebrafish (a model organism), Rio Negro DOC provided almost perfect protection against ionoregulatory disturbances associated with acute exposure to pH 4.0 in ion-poor water. DOC reduced diffusive losses of Na(+) and Cl(-), and promoted a remarkable stimulation of Na(+) uptake that otherwise would have been completely inhibited. Additionally, prior acclimation to DOC at neutral pH reduced rates of branchial Na(+) turnover, and provided similar protection against acid-induced ionoregulatory disturbances, even if the DOC was no longer present. These results reinforce the important roles that DOC molecules can play in the regulation of gill functions in freshwater fish, particularly in ion-poor, acidic blackwaters.
Collapse
Affiliation(s)
- Rafael M. Duarte
- Laboratory of Ecophysiology and Molecular Evolution, National Institute for Amazonian Research, Manaus, AM, Brazil
- Biosciences Institute, São Paulo State University - UNESP, Coastal Campus, São Vicente, SP, Brazil
| | - D. Scott Smith
- Department of Chemistry and Biochemistry, Wilfrid Laurier University, Waterloo, ON, N2L 3C5, Canada
| | - Adalberto L. Val
- Laboratory of Ecophysiology and Molecular Evolution, National Institute for Amazonian Research, Manaus, AM, Brazil
| | - Chris M. Wood
- Laboratory of Ecophysiology and Molecular Evolution, National Institute for Amazonian Research, Manaus, AM, Brazil
- Department of Biology, McMaster University, Hamilton, ON L8S 4K1, Canada
- Department of Zoology, University of British Columbia, Vancouver, BC V6T 1Z4, Canada
| |
Collapse
|
39
|
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.
Collapse
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
| |
Collapse
|
40
|
Nawata CM, Walsh PJ, Wood CM. Physiological and molecular responses of the spiny dogfish shark (Squalus acanthias) to high environmental ammonia: scavenging for nitrogen. ACTA ACUST UNITED AC 2015; 218:238-48. [PMID: 25609784 DOI: 10.1242/jeb.114967] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
In teleosts, a branchial metabolon links ammonia excretion to Na(+) uptake via Rh glycoproteins and other transporters. Ureotelic elasmobranchs are thought to have low branchial ammonia permeability, and little is known about Rh function in this ancient group. We cloned Rh cDNAs (Rhag, Rhbg and Rhp2) and evaluated gill ammonia handling in Squalus acanthias. Control ammonia excretion was <5% of urea-N excretion. Sharks exposed to high environmental ammonia (HEA; 1 mmol(-1) NH4HCO3) for 48 h exhibited active ammonia uptake against partial pressure and electrochemical gradients for 36 h before net excretion was re-established. Plasma total ammonia rose to seawater levels by 2 h, but dropped significantly below them by 24-48 h. Control ΔP(NH3) (the partial pressure gradient of NH3) across the gills became even more negative (outwardly directed) during HEA. Transepithelial potential increased by 30 mV, negating a parallel rise in the Nernst potential, such that the outwardly directed NH4(+) electrochemical gradient remained unchanged. Urea-N excretion was enhanced by 90% from 12 to 48 h, more than compensating for ammonia-N uptake. Expression of Rhp2 (gills, kidney) and Rhbg (kidney) did not change, but branchial Rhbg and erythrocytic Rhag declined during HEA. mRNA expression of branchial Na(+)/K(+)-ATPase (NKA) increased at 24 h and that of H(+)-ATPase decreased at 48 h, while expression of the potential metabolon components Na(+)/H(+) exchanger2 (NHE2) and carbonic anhydrase IV (CA-IV) remained unchanged. We propose that the gill of this nitrogen-limited predator is poised not only to minimize nitrogen loss by low efflux permeability to urea and ammonia but also to scavenge ammonia-N from the environment during HEA to enhance urea-N synthesis.
Collapse
Affiliation(s)
- C Michele Nawata
- Bamfield Marine Sciences Centre, 100 Pachena Road, Bamfield, BC, Canada V0R 1B0 Department of Biology, McMaster University, 1280 Main Street, West, Hamilton, ON, Canada L8S 4K1 Department of Physiology, University of Arizona, 1501 N. Campbell Avenue Tucson, AZ 85724, USA
| | - Patrick J Walsh
- Bamfield Marine Sciences Centre, 100 Pachena Road, Bamfield, BC, Canada V0R 1B0 Department of Biology and Centre for Advanced Research in Environmental Genomics, University of Ottawa, Ottawa, ON, Canada K1N 6N5
| | - Chris M Wood
- Bamfield Marine Sciences Centre, 100 Pachena Road, Bamfield, BC, Canada V0R 1B0 Department of Biology, McMaster University, 1280 Main Street, West, Hamilton, ON, Canada L8S 4K1 Department of Zoology, University of British Columbia, #4321-6270 University Boulevard, Vancouver, BC, Canada V6T 1Z4
| |
Collapse
|
41
|
You X, Bian C, Zan Q, Xu X, Liu X, Chen J, Wang J, Qiu Y, Li W, Zhang X, Sun Y, Chen S, Hong W, Li Y, Cheng S, Fan G, Shi C, Liang J, Tom Tang Y, Yang C, Ruan Z, Bai J, Peng C, Mu Q, Lu J, Fan M, Yang S, Huang Z, Jiang X, Fang X, Zhang G, Zhang Y, Polgar G, Yu H, Li J, Liu Z, Zhang G, Ravi V, Coon SL, Wang J, Yang H, Venkatesh B, Wang J, Shi Q. Mudskipper genomes provide insights into the terrestrial adaptation of amphibious fishes. Nat Commun 2014; 5:5594. [PMID: 25463417 PMCID: PMC4268706 DOI: 10.1038/ncomms6594] [Citation(s) in RCA: 107] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2014] [Accepted: 10/16/2014] [Indexed: 01/18/2023] Open
Abstract
Mudskippers are amphibious fishes that have developed morphological and physiological adaptations to match their unique lifestyles. Here we perform whole-genome sequencing of four representative mudskippers to elucidate the molecular mechanisms underlying these adaptations. We discover an expansion of innate immune system genes in the mudskippers that may provide defence against terrestrial pathogens. Several genes of the ammonia excretion pathway in the gills have experienced positive selection, suggesting their important roles in mudskippers’ tolerance to environmental ammonia. Some vision-related genes are differentially lost or mutated, illustrating genomic changes associated with aerial vision. Transcriptomic analyses of mudskippers exposed to air highlight regulatory pathways that are up- or down-regulated in response to hypoxia. The present study provides a valuable resource for understanding the molecular mechanisms underlying water-to-land transition of vertebrates. Mudskippers are amphibious fishes that have adapted to live on mudflats. Here, the authors sequence the genomes of four different mudskipper species and highlight genetic changes that may have had an evolutionary role in the water-to-land transition of vertebrates.
Collapse
Affiliation(s)
- Xinxin You
- 1] Shenzhen Key Lab of Marine Genomics, State Key Laboratory of Agricultural Genomics, Shenzhen 518083, China [2] BGI-Shenzhen, Shenzhen 518083, China
| | - Chao Bian
- 1] Shenzhen Key Lab of Marine Genomics, State Key Laboratory of Agricultural Genomics, Shenzhen 518083, China [2] BGI-Shenzhen, Shenzhen 518083, China
| | - Qijie Zan
- Shenzhen Wild Animal Rescue Center, Shenzhen 518040, China
| | - Xun Xu
- BGI-Shenzhen, Shenzhen 518083, China
| | - Xin Liu
- BGI-Shenzhen, Shenzhen 518083, China
| | - Jieming Chen
- 1] Shenzhen Key Lab of Marine Genomics, State Key Laboratory of Agricultural Genomics, Shenzhen 518083, China [2] BGI-Shenzhen, Shenzhen 518083, China
| | | | - Ying Qiu
- 1] Shenzhen Key Lab of Marine Genomics, State Key Laboratory of Agricultural Genomics, Shenzhen 518083, China [2] BGI-Shenzhen, Shenzhen 518083, China
| | - Wujiao Li
- Shenzhen Key Lab of Marine Genomics, State Key Laboratory of Agricultural Genomics, Shenzhen 518083, China
| | - Xinhui Zhang
- 1] Shenzhen Key Lab of Marine Genomics, State Key Laboratory of Agricultural Genomics, Shenzhen 518083, China [2] BGI-Shenzhen, Shenzhen 518083, China
| | - Ying Sun
- BGI-Shenzhen, Shenzhen 518083, China
| | - Shixi Chen
- College of Ocean and Earth Science, Xiamen University, Xiamen 361005, China
| | - Wanshu Hong
- College of Ocean and Earth Science, Xiamen University, Xiamen 361005, China
| | | | | | | | | | - Jie Liang
- BGI-Shenzhen, Shenzhen 518083, China
| | | | | | - Zhiqiang Ruan
- 1] Shenzhen Key Lab of Marine Genomics, State Key Laboratory of Agricultural Genomics, Shenzhen 518083, China [2] BGI-Shenzhen, Shenzhen 518083, China
| | - Jie Bai
- 1] Shenzhen Key Lab of Marine Genomics, State Key Laboratory of Agricultural Genomics, Shenzhen 518083, China [2] BGI-Shenzhen, Shenzhen 518083, China
| | - Chao Peng
- 1] Shenzhen Key Lab of Marine Genomics, State Key Laboratory of Agricultural Genomics, Shenzhen 518083, China [2] BGI-Shenzhen, Shenzhen 518083, China
| | - Qian Mu
- BGI-Shenzhen, Shenzhen 518083, China
| | - Jun Lu
- 1] BGI-Shenzhen, Shenzhen 518083, China [2] Shenzhen BGI Fisheries Sci &Tech Co. Ltd, Shenzhen 518083, China
| | - Mingjun Fan
- Center for Fish Genomics, BGI-Wuhan, Wuhan 430075, China
| | - Shuang Yang
- 1] BGI-Shenzhen, Shenzhen 518083, China [2] Center for Fish Genomics, BGI-Wuhan, Wuhan 430075, China
| | | | | | | | | | | | - Gianluca Polgar
- Environmental and Life Sciences Programme, Faculty of Science, Universiti Brunei Darussalam, Jln Tungku Link, BE1410 Brunei Darussalam
| | - Hui Yu
- 1] Shenzhen Key Lab of Marine Genomics, State Key Laboratory of Agricultural Genomics, Shenzhen 518083, China [2] BGI-Shenzhen, Shenzhen 518083, China
| | - Jia Li
- 1] Shenzhen Key Lab of Marine Genomics, State Key Laboratory of Agricultural Genomics, Shenzhen 518083, China [2] BGI-Shenzhen, Shenzhen 518083, China
| | - Zhongjian Liu
- Shenzhen Key Laboratory for Orchid Conservation and Utilization of the Orchid Conservation and Research Center of Shenzhen, Shenzhen 518114, China
| | - Guoqiang Zhang
- Shenzhen Key Laboratory for Orchid Conservation and Utilization of the Orchid Conservation and Research Center of Shenzhen, Shenzhen 518114, China
| | - Vydianathan Ravi
- Institute of Molecular and Cell Biology, A*STAR, Biopolis, Singapore 138673, Singapore
| | - Steven L Coon
- Molecular Genomics Laboratory, National Institutes of Health, Bethesda, Maryland 20892, USA
| | - Jian Wang
- 1] BGI-Shenzhen, Shenzhen 518083, China [2] James D. Watson Institute of Genome Science, Hangzhou 310008, China
| | - Huanming Yang
- 1] BGI-Shenzhen, Shenzhen 518083, China [2] James D. Watson Institute of Genome Science, Hangzhou 310008, China [3] Princess Al Jawhara Center of Excellence in the Research of Hereditary Disorders, King Abdulaziz University, Jeddah, Saudi Arabia
| | - Byrappa Venkatesh
- Institute of Molecular and Cell Biology, A*STAR, Biopolis, Singapore 138673, Singapore
| | - Jun Wang
- 1] BGI-Shenzhen, Shenzhen 518083, China [2] Princess Al Jawhara Center of Excellence in the Research of Hereditary Disorders, King Abdulaziz University, Jeddah, Saudi Arabia [3] Department of Biology, University of Copenhagen, DK-2200 Copenhagen, Denmark
| | - Qiong Shi
- 1] Shenzhen Key Lab of Marine Genomics, State Key Laboratory of Agricultural Genomics, Shenzhen 518083, China [2] BGI-Shenzhen, Shenzhen 518083, China [3] Shenzhen BGI Fisheries Sci &Tech Co. Ltd, Shenzhen 518083, China [4] Center for Fish Genomics, BGI-Wuhan, Wuhan 430075, China
| |
Collapse
|
42
|
Boyle D, Clifford AM, Orr E, Chamot D, Goss GG. Mechanisms of Cl(-) uptake in rainbow trout: cloning and expression of slc26a6, a prospective Cl(-)/HCO3(-) exchanger. Comp Biochem Physiol A Mol Integr Physiol 2014; 180:43-50. [PMID: 25446148 DOI: 10.1016/j.cbpa.2014.11.001] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2014] [Revised: 10/27/2014] [Accepted: 11/02/2014] [Indexed: 10/24/2022]
Abstract
In fresh waters, fishes continuously acquire ions to offset diffusive losses to a more dilute ambient environment and to maintain acid-base status. The objectives of the present study were to clone slc26a6, a prospective Cl(-)/HCO3(-) exchanger from rainbow trout, investigate its expression patterns in various tissues, at different developmental stages and after differential salinity exposure, and probe the mechanisms of Cl(-) uptake in rainbow trout embryos during development using a pharmacological inhibitor approach combined with (36)Cl(-) unidirectional fluxes. Results showed that the cloned gene encoded a 783 amino acid protein with conserved domains characteristic of the SLC26a family of anion exchange proteins. Phylogenetic analysis of this sequence against all subfamilies of the SLC26a family demonstrated that this translated protein shared a common ancestor with other actinopterygii and mammalian SLC26a6 isoforms and thus confirmed the identity of the cloned gene. Expression of slc26a6 was detected in all tissues and developmental stages assayed but was highest in the gill of juvenile trout. In trout embryos, Cl(-) uptake increased significantly post-hatch and was demonstrated to be mediated via an anion exchanger specific (DIDS sensitive) pathway that was also sensitive to hypercapnia. This parallels well with the predicted function of slc26a6, and the detection of the transcript in embryos and tissues of trout. In conclusion, this study is the first report of slc26a6 in rainbow trout and functional and expression analyses indicate its likely involvement in Cl(-)/HCO3(-) exchange in two life stages of rainbow trout.
Collapse
Affiliation(s)
- David Boyle
- Department of Biological Sciences, University of Alberta, Edmonton, Alberta T6G 2E9, Canada
| | - Alexander M Clifford
- Department of Biological Sciences, University of Alberta, Edmonton, Alberta T6G 2E9, Canada
| | - Elizabeth Orr
- 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.
| |
Collapse
|
43
|
Zhang L, Michele Nawata C, De Boeck G, Wood CM. Rh protein expression in branchial neuroepithelial cells, and the role of ammonia in ventilatory control in fish. Comp Biochem Physiol A Mol Integr Physiol 2014; 186:39-51. [PMID: 25465530 DOI: 10.1016/j.cbpa.2014.10.004] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2014] [Revised: 10/14/2014] [Accepted: 10/14/2014] [Indexed: 01/02/2023]
Abstract
Bill Milsom has made seminal contributions to our understanding of ventilatory control in a wide range of vertebrates. Teleosts are particularly interesting, because they produce a 3rd, potentially toxic respiratory gas (ammonia) in large amounts. Fish are well known to hyperventilate under high environmental ammonia (HEA), but only recently has the potential role of ammonia in normal ventilatory control been investigated. It is now clear that ammonia can act directly as a ventilatory stimulant in trout, independent of its effects on acid-base balance. Even in ureotelic dogfish sharks, acute elevations in ammonia cause increases in ventilation. Peripherally, the detection of elevated ammonia resides in gill arches I and II in trout, and in vitro, neuroepithelial cells (NECs) from these arches are sensitive to ammonia, responding with elevations in intracellular Ca(2+) ([Ca(2+)]i). Centrally, hyperventilatory responses to ammonia correlate more closely with concentrations of ammonia in the brain than in plasma or CSF. After chronic HEA exposure, ventilatory responsiveness to ammonia is lost, associated with both an attenuation of the [Ca(2+)]i response in NECs, and the absence of elevation in brain ammonia concentration. Chronic exposure to HEA also causes increases in the mRNA expression of several Rh proteins (ammonia-conductive channels) in both brain and gills. "Single cell" PCR techniques have been used to isolate the individual responses of NECs versus other gill cell types. We suggest several circumstances (post-feeding, post-exercise) where the role of ammonia as a ventilatory stimulant may have adaptive benefits for O2 uptake in fish.
Collapse
Affiliation(s)
- Li Zhang
- Dept. of Biology, McMaster University, Hamilton, Canada; Key Laboratory of Marine Bio-resources Sustainable Utilization, South China Sea Institute of Oceanology, Guangzhou, China
| | - C Michele Nawata
- Dept. of Biology, McMaster University, Hamilton, Canada; Dept. of Physiology, University of Arizona, Tucson, USA; Bamfield Marine Sciences Centre, Bamfield, Canada
| | - Gudrun De Boeck
- Bamfield Marine Sciences Centre, Bamfield, Canada; SPHERE, Dept. of Biology, University of Antwerp, Antwerp, Belgium
| | - Chris M Wood
- Dept. of Biology, McMaster University, Hamilton, Canada; Bamfield Marine Sciences Centre, Bamfield, Canada; Dept. of Zoology, University of British Columbia, Vancouver, Canada.
| |
Collapse
|
44
|
Wood CM, Robertson LM, Johannsson OE, Val AL. Mechanisms of Na+ uptake, ammonia excretion, and their potential linkage in native Rio Negro tetras (Paracheirodon axelrodi, Hemigrammus rhodostomus, and Moenkhausia diktyota). J Comp Physiol B 2014; 184:877-90. [PMID: 25106686 DOI: 10.1007/s00360-014-0847-7] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2014] [Revised: 07/10/2014] [Accepted: 07/19/2014] [Indexed: 12/13/2022]
Abstract
Mechanisms of Na(+) uptake, ammonia excretion, and their potential linkage were investigated in three characids (cardinal, hemigrammus, moenkhausia tetras), using radiotracer flux techniques to study the unidirectional influx (J in), efflux (J out), and net flux rates (J net) of Na(+) and Cl(-), and the net excretion rate of ammonia (J Amm). The fish were collected directly from the Rio Negro, and studied in their native "blackwater" which is acidic (pH 4.5), ion-poor (Na(+), Cl(-) ~20 µM), and rich in dissolved organic matter (DOM 11.5 mg C l(-1)). J in (Na) , J in (Cl) , and J Amm were higher than in previous reports on tetras obtained from the North America aquarium trade and/or studied in low DOM water. In all three species, J in (Na) was unaffected by amiloride (10(-4) M, NHE and Na(+) channel blocker), but both J in (Na) and J in (Cl) were virtually eliminated (85-99 % blockade) by AgNO3 (10(-7) M). A time course study on cardinal tetras demonstrated that J in (Na) blockade by AgNO3 was very rapid (<5 min), suggesting inhibition of branchial carbonic anhydrase (CA), and exposure to the CA-blocker acetazolamide (10(-4) M) caused a 50 % reduction in J in (Na) .. Additionally, J in (Na) was unaffected by phenamil (10(-5) M, Na(+) channel blocker), bumetanide (10(-4) M, NKCC blocker), hydrochlorothiazide (5 × 10(-3) M, NCC blocker), and exposure to an acute 3 unit increase in water pH. None of these treatments, including partial or complete elimination of J in (Na) (by acetazolamide and AgNO3 respectively), had any inhibitory effect on J Amm. Therefore, Na(+) uptake in Rio Negro tetras depends on an internal supply of H(+) from CA, but does not fit any of the currently accepted H(+)-dependent models (NHE, Na(+) channel/V-type H(+)-ATPase), or co-transport schemes (NCC, NKCC), and ammonia excretion does not fit the current "Na(+)/NH4 (+) exchange metabolon" paradigm. Na(+), K(+)-ATPase and V-type H(+)-ATPase activities were present at similar levels in gill homogenates, Acute exposure to high environmental ammonia (NH4Cl, 10(-3) M) significantly increased J in (Na) , and NH4 (+) was equally or more effective than K(+) in activating branchial Na(+),(K(+)) ATPase activity in vitro. We propose that ammonia excretion does not depend on Na(+) uptake, but that Na(+) uptake (by an as yet unknown H(+)-dependent apical mechanism) depends on ammonia excretion, driven by active NH4 (+) entry via basolateral Na(+),(K(+))-ATPase.
Collapse
Affiliation(s)
- Chris M Wood
- Department of Biology, McMaster University, 1280 Main St. West, Hamilton, ON, L8S 4K1, Canada,
| | | | | | | |
Collapse
|
45
|
Kumai Y, Porteus CS, Kwong RWM, Perry SF. Hydrogen sulfide inhibits Na+ uptake in larval zebrafish, Danio rerio. Pflugers Arch 2014; 467:651-64. [PMID: 24939700 DOI: 10.1007/s00424-014-1550-y] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2013] [Revised: 05/31/2014] [Accepted: 06/02/2014] [Indexed: 12/28/2022]
Abstract
The present study investigated the role of hydrogen sulfide (H2S) in regulating Na(+) uptake in larval zebrafish, Danio rerio. Waterborne treatment of larvae at 4 days post-fertilization (dpf) with Na2S or GYY-4137 (chemicals known to generate H2S) significantly reduced Na(+) uptake. Exposure of larvae to water enriched with NaCl (1 mM NaCl) caused a pronounced reduction in Na(+) uptake which was prevented by pharmacological inhibition of cystathionine β-synthase (CBS) or cystathionine γ-lyase (CSE), two key enzymes involved in the endogenous synthesis of H2S. Furthermore, translational gene knockdown of CSE and CBSb significantly increased the basal rate of Na(+) uptake. Waterborne treatment with Na2S significantly decreased whole-body acid excretion and reduced Na(+) uptake in larval zebrafish preexposed to acidic (pH 4.0) water (a condition shown to promote Na(+) uptake via Na(+)-H(+)-exchanger 3b, NHE3b). However, Na2S did not affect Na(+) uptake in larvae depleted of NHE3b-containing ionocytes (HR cells) after knockdown of transcription factor glial cell missing 2 (gcm2) in which Na(+) uptake occurs predominantly via Na(+)-Cl(-) co-transporter (NCC)-containing cells. These observations suggest that Na(+) uptake via NHE3b, but not NCC, is regulated by H2S. Whole-mount immunohistochemistry demonstrated that ionocytes expressing NHE3b also express CSE. These data suggests a physiologically relevant role of H2S as a mechanism to lower Na(+) uptake in zebrafish larvae, probably through its inhibitory action on NHE3b.
Collapse
Affiliation(s)
- Yusuke Kumai
- Department of Biology, University of Ottawa, 30 Marie Curie, Ottawa, ON, K1N 6N5, Canada
| | | | | | | |
Collapse
|
46
|
Kwong RWM, Kumai Y, Perry SF. The physiology of fish at low pH: the zebrafish as a model system. J Exp Biol 2014; 217:651-62. [DOI: 10.1242/jeb.091603] [Citation(s) in RCA: 81] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Ionic regulation and acid–base balance are fundamental to the physiology of vertebrates including fish. Acidification of freshwater ecosystems is recognized as a global environmental problem, and the physiological responses to acid exposure in a few fish species are well characterized. However, the underlying mechanisms promoting ionic and acid–base balance for most fish species that have been investigated remain unclear. Zebrafish (Danio rerio) has emerged as a powerful model system to elucidate the molecular basis of ionic and acid–base regulation. The utility of zebrafish is related to the ease with which it can be genetically manipulated, its suitability for state-of-the-art molecular and cellular approaches, and its tolerance to diverse environmental conditions. Recent studies have identified several key regulatory mechanisms enabling acclimation of zebrafish to acidic environments, including activation of the sodium/hydrogen exchanger (NHE) and H+-ATPase for acid secretion and Na+ uptake, cortisol-mediated regulation of transcellular and paracellular Na+ movements, and ionocyte proliferation controlled by specific cell-fate transcription factors. These integrated physiological responses ultimately contribute to ionic and acid–base homeostasis in zebrafish exposed to acidic water. In the present review, we provide an overview of the general effects of acid exposure on freshwater fish, the adaptive mechanisms promoting extreme acid tolerance in fishes native to acidic environments, and the mechanisms regulating ionic and acid–base balance during acid exposure in zebrafish.
Collapse
Affiliation(s)
- Raymond W. M. Kwong
- Department of Biology, University of Ottawa, 30 Marie Curie, Ottawa, ON, Canada, K1N 6N5
| | - Yusuke Kumai
- Department of Biology, University of Ottawa, 30 Marie Curie, Ottawa, ON, Canada, K1N 6N5
| | - Steve F. Perry
- Department of Biology, University of Ottawa, 30 Marie Curie, Ottawa, ON, Canada, K1N 6N5
| |
Collapse
|
47
|
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.
Collapse
Affiliation(s)
- Yusuke Ito
- Department of Biological Sciences, Tokyo Institute of Technology, Yokohama, Japan; and
| | | | | | | | | |
Collapse
|
48
|
Kumai Y, Kwong RWM, Perry SF. The role of cAMP-mediated intracellular signaling in regulating Na+ uptake in zebrafish larvae. Am J Physiol Regul Integr Comp Physiol 2013; 306:R51-60. [PMID: 24259461 DOI: 10.1152/ajpregu.00317.2013] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
In the current study, the role of cAMP in stimulating Na(+) uptake in larval zebrafish was investigated. Treating larvae at 4 days postfertilization (dpf) with 10 μM forskolin or 1 μM 8-bromo cAMP significantly increased Na(+) uptake by three-fold and twofold, respectively. The cAMP-dependent stimulation of Na(+) uptake was probably unrelated to protein trafficking via microtubules because pretreatment with 200 μM colchicine or 30 μM nocodazole did not attenuate the magnitude of the response. Na(+) uptake was stimulated markedly following acute (2 h) exposure to acidic water. The acid-induced increase in Na(+) uptake was accompanied by a twofold elevation in whole body cAMP levels and attenuated by inhibiting PKA with 10 μM H-89. Knockdown of Na(+)-H(+) exchanger 3b (NHE3b) attenuated, but did not abolish, the stimulation of Na(+) uptake during forskolin treatment. In glial cell missing 2 morphants, in which the role of NHE3b in Na(+) uptake is diminished and the Na(+)-Cl(-) cotransporter (NCC) becomes the predominant route of Na(+) entry, forskolin treatment continued to increase Na(+) uptake. These data suggest that at least NHE3b and NCC are targeted by cAMP in zebrafish larvae. Staining of larvae with fluorescent forskolin and propranolol revealed the presence of transmembrane adenylyl cyclase within multiple subtypes of ionocytes expressing β-adrenergic receptors. Taken together, results of the present study demonstrate that cAMP-mediated intracellular signaling may regulate multiple Na(+) transporters and plays an important role in regulating Na(+) uptake in zebrafish larvae during acute exposure to an acidic environment.
Collapse
Affiliation(s)
- Yusuke Kumai
- Department of Biology, University of Ottawa, Ottawa, Ontario, Canada
| | | | | |
Collapse
|
49
|
Zimmer AM, Brauner CJ, Wood CM. Ammonia transport across the skin of adult rainbow trout (Oncorhynchus mykiss) exposed to high environmental ammonia (HEA). J Comp Physiol B 2013; 184:77-90. [PMID: 24114656 DOI: 10.1007/s00360-013-0784-x] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2013] [Revised: 09/04/2013] [Accepted: 09/23/2013] [Indexed: 12/27/2022]
Abstract
Recent molecular evidence points towards a capacity for ammonia transport across the skin of adult rainbow trout. A series of in vivo and in vitro experiments were conducted to understand the role of cutaneous ammonia excretion (J amm) under control conditions and after 12-h pre-exposure to high environmental ammonia (HEA; 2 mmol/l NH4HCO3). Divided chamber experiments with bladder-catheterized, rectally ligated fish under light anesthesia were performed to separate cutaneous J amm from branchial, renal, and intestinal J amm. Under control conditions, cutaneous J amm accounted for 4.5 % of total J amm in vivo. In fish pre-exposed to HEA, plasma total ammonia concentration increased 20-fold to approximately 1,000 μmol/l, branchial J amm increased 1.5- to 2.7-fold, and urinary J amm increased about 7-fold. Urinary J amm still accounted for less than 2 % of total J amm. Cutaneous J amm increased 4-fold yet amounted to only 5.7 % of total J amm in these fish. Genes (Rhcg1, Rhcg2, Rhbg, NHE-2, v-type H(+)-ATPase) known to be involved in ammonia excretion at the gills of trout were all expressed at the mRNA level in the skin, but their expression did not increase with HEA pre-exposure. In vitro analyses using [(14)C] methylamine (MA), an ammonia analog which is transported by Rh proteins, demonstrated that MA permeability in isolated skin sections was higher in HEA pre-exposed fish than in control fish. The addition of basolateral ammonia (1,000 μmol/l) to this system abolished this increase in permeability, suggesting ammonia competition with MA for Rh-mediated transport across the skin of HEA pre-exposed trout; this did not occur in skin sections from control trout. Moreover, in vitro J amm by the skin of fish which had been pre-exposed to HEA was also higher than in control fish in the absence of basolateral ammonia, pointing towards a possible cutaneous ammonia loading in response to HEA. In vitro MA permeability was reduced upon the addition of amiloride (10(-4) mol/l), but not phenamil (10(-5) mol/l) suggesting a role for a Na/H-exchanger (NHE) in cutaneous ammonia transport, as has been previously described in the skin of larval fish. Overall, it appears that under control conditions and in response to HEA pre-exposure, the skin makes only a very minor contribution to total J amm, but the observed increases in cutaneous J amm in vivo and in cutaneous J amm and MA permeability in vitro demonstrate the capacity for ammonia transport in the skin of adult trout. It remains unclear if this capacity may become significant under certain environmental challenges or if it is merely a remnant of cutaneous transport capacity from early life stages in these fish.
Collapse
Affiliation(s)
- Alex M Zimmer
- Department of Biology, McMaster University, Hamilton, ON, L8S 4K1, Canada,
| | | | | |
Collapse
|
50
|
Peña-Münzenmayer G, Niemeyer MI, Sepúlveda FV, Cid LP. Zebrafish and mouse TASK-2 K(+) channels are inhibited by increased CO2 and intracellular acidification. Pflugers Arch 2013; 466:1317-27. [PMID: 24081451 DOI: 10.1007/s00424-013-1365-2] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2013] [Revised: 09/12/2013] [Accepted: 09/13/2013] [Indexed: 11/28/2022]
Abstract
TASK-2 is a K2P K(+) channel considered as a candidate to mediate CO2 sensing in central chemosensory neurons in mouse. Neuroepithelial cells in zebrafish gills sense CO2 levels through an unidentified K2P K(+) channel. We have now obtained zfTASK-2 from zebrafish gill tissue that is 49 % identical to mTASK-2. Like its mouse equivalent, it is gated both by extra- and intracellular pH being activated by alkalinization and inhibited by acidification. The pHi dependence of zfTASK-2 is similar to that of mTASK-2, with pK 1/2 values of 7.9 and 8.0, respectively, but pHo dependence occurs with a pK 1/2 of 8.8 (8.0 for mTASK-2) in line with the relatively alkaline plasma pH found in fish. Increasing CO2 led to a rapid, concentration-dependent (IC50 ~1.5 % CO2) inhibition of mouse and zfTASK-2 that could be resolved into an inhibition by intracellular acidification and a CO2 effect independent of pHi change. Indeed a CO2 effect persisted despite using strongly buffered intracellular solutions abolishing any change in pHi, was present in TASK-2-K245A mutant insensitive to pHi, and also under carbonic anhydrase inhibition. The mechanism by which TASK-2 senses CO2 is unknown but requires the presence of the 245-273 stretch of amino acids in the C terminus that comprises numerous basic amino acids and is important in TASK-2 G protein subunit binding and regulation of the channel. The described CO2 effect might be of importance in the eventual roles played by TASK-2 in chemoreception in mouse and zebrafish.
Collapse
|