1
|
Oehlert AM, Garza J, Nixon S, Frank L, Folkerts EJ, Stieglitz JD, Lu C, Heuer RM, Benetti DD, Del Campo J, Gomez FA, Grosell M. Implications of dietary carbon incorporation in fish carbonates for the global carbon cycle. THE SCIENCE OF THE TOTAL ENVIRONMENT 2024; 916:169895. [PMID: 38215854 DOI: 10.1016/j.scitotenv.2024.169895] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/05/2023] [Revised: 12/18/2023] [Accepted: 01/02/2024] [Indexed: 01/14/2024]
Abstract
Marine bony fish are important participants in Earth's carbon cycle through their contributions to the biological pump and the marine inorganic carbon cycle. However, uncertainties in the composition and magnitude of fish contributions preclude their integration into fully coupled carbon-climate models. Here, we consider recent upwards revisions to global fish biomass estimates (2.7-9.5×) and provide new stable carbon isotope measurements that show marine fish are prodigious producers of carbonate with unique composition. Assuming the median increase (4.17×) in fish biomass estimates is linearly reflected in fish carbonate (ichthyocarbonate) production rate, marine fish are estimated to produce between 1.43 and 3.99 Pg CaCO3 yr-1, but potentially as much as 9.03 Pg CaCO3 yr-1. Thus, marine fish carbonate production is equivalent to or potentially higher than contributions by coccolithophores or pelagic foraminifera. New stable carbon isotope analyses indicate that a significant proportion of ichthyocarbonate is derived from dietary carbon, rather than seawater dissolved inorganic carbon. Using a statistical mixing model to derive source contributions, we estimate ichthyocarbonate contains up to 81 % dietary carbon, with average compositions of 28-56 %, standing in contrast to contents <10 % in other biogenic carbonate minerals. Results also indicate ichthyocarbonate contains 5.5-40.4 % total organic carbon. When scaled to the median revised global production of ichthyocarbonate, an additional 0.08 to 1.61 Pg C yr-1 can potentially be added to estimates of fish contributions to the biological pump, significantly increasing marine fish contributions to total surface carbon export. Our integration of geochemical and physiological analyses identifies an overlooked link between carbonate production and the biological pump. Since ichthyocarbonate production is anticipated to increase with climate change scenarios, due to ocean warming and acidification, these results emphasize the importance of quantitative understanding of the multifaceted role of marine fish in the global carbon cycle.
Collapse
Affiliation(s)
- Amanda M Oehlert
- Department of Marine Geosciences, Rosenstiel School of Marine, Atmospheric, and Earth Science, University of Miami, FL, United States of America.
| | - Jazmin Garza
- Department of Marine Geosciences, Rosenstiel School of Marine, Atmospheric, and Earth Science, University of Miami, FL, United States of America
| | - Sandy Nixon
- Department of Marine Biology and Ecology, Rosenstiel School of Marine, Atmospheric, and Earth Science, University of Miami, FL, United States of America
| | - LeeAnn Frank
- Department of Marine Biology and Ecology, Rosenstiel School of Marine, Atmospheric, and Earth Science, University of Miami, FL, United States of America
| | - Erik J Folkerts
- Department of Marine Biology and Ecology, Rosenstiel School of Marine, Atmospheric, and Earth Science, University of Miami, FL, United States of America
| | - John D Stieglitz
- Department of Marine Biology and Ecology, Rosenstiel School of Marine, Atmospheric, and Earth Science, University of Miami, FL, United States of America
| | - Chaojin Lu
- Department of Marine Geosciences, Rosenstiel School of Marine, Atmospheric, and Earth Science, University of Miami, FL, United States of America
| | - Rachael M Heuer
- Department of Marine Biology and Ecology, Rosenstiel School of Marine, Atmospheric, and Earth Science, University of Miami, FL, United States of America
| | - Daniel D Benetti
- Department of Marine Biology and Ecology, Rosenstiel School of Marine, Atmospheric, and Earth Science, University of Miami, FL, United States of America
| | - Javier Del Campo
- Department of Marine Biology and Ecology, Rosenstiel School of Marine, Atmospheric, and Earth Science, University of Miami, FL, United States of America; Institut de Biologia Evolutiva (CSIC - Universitat Pompeu Fabra), Barcelona, Spain
| | - Fabian A Gomez
- Northern Gulf Institute, Mississippi State University, MS, United States of America; NOAA Atlantic Oceanographic and Meteorological Laboratory, Miami, FL, United States of America
| | - Martin Grosell
- Department of Marine Biology and Ecology, Rosenstiel School of Marine, Atmospheric, and Earth Science, University of Miami, FL, United States of America
| |
Collapse
|
2
|
Folkerts EJ, Oehlert AM, Heuer RM, Nixon S, Stieglitz JD, Grosell M. The role of marine fish-produced carbonates in the oceanic carbon cycle is determined by size, specific gravity, and dissolution rate. THE SCIENCE OF THE TOTAL ENVIRONMENT 2024; 916:170044. [PMID: 38244625 DOI: 10.1016/j.scitotenv.2024.170044] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/22/2023] [Revised: 01/05/2024] [Accepted: 01/07/2024] [Indexed: 01/22/2024]
Abstract
Rising CO2 emissions have heightened the necessity for increased understanding of Earth's carbon cycle to predict future climates. The involvement of marine planktonic species in the global carbon cycle has been extensively studied, but contributions by marine fish remain poorly characterized. Marine teleost fishes produce carbonate minerals ('ichthyocarbonates') within the lumen of their intestines which are excreted at significant rates on a global scale. However, we have limited understanding of the fate of excreted ichthyocarbonate. We analyzed ichthyocarbonate produced by three different marine teleosts for mol%MgCO3 content, size, specific gravity, and dissolution rate to gain a better understanding of ichthyocarbonate fate. Based on the species examined here, we report that 75 % of ichthyocarbonates are ≤0.91 mm in diameter. Analyses indicate high Mg2+ content across species (22.3 to 32.3 % mol%MgCO3), consistent with previous findings. Furthermore, ichthyocarbonate specific gravity ranged from 1.23 to 1.33 g/cm3, and ichthyocarbonate dissolution rates varied among species as a function of aragonite saturation state. Ichthyocarbonate sinking rates and dissolution depth were estimated for the Atlantic, Pacific, and Indian ocean basins for the three species examined. In the North Atlantic, for example, ~33 % of examined ichthyocarbonates are expected to reach depths exceeding 200 m prior to complete dissolution. The remaining ~66 % of ichthyocarbonate is estimated to dissolve and contribute to shallow water alkalinity budgets. Considering fish biomass and ichthyocarbonate production rates, our results support that marine fishes are critical to the global carbon cycle, contributing to oceanic alkalinity budgets and thereby influencing the ability of the oceans to neutralize atmospheric CO2.
Collapse
Affiliation(s)
- Erik J Folkerts
- Department of Marine Biology and Ecology, Rosenstiel School of Marine, Atmospheric, and Earth Science, University of Miami, Miami, FL 33149, United States of America.
| | - Amanda M Oehlert
- Department of Marine Geosciences, Rosenstiel School of Marine, Atmospheric, and Earth Science, University of Miami, Miami, FL 33149, United States of America
| | - Rachael M Heuer
- Department of Marine Biology and Ecology, Rosenstiel School of Marine, Atmospheric, and Earth Science, University of Miami, Miami, FL 33149, United States of America
| | - Sandy Nixon
- Department of Marine Biology and Ecology, Rosenstiel School of Marine, Atmospheric, and Earth Science, University of Miami, Miami, FL 33149, United States of America
| | - John D Stieglitz
- Department of Marine Biology and Ecology, Rosenstiel School of Marine, Atmospheric, and Earth Science, University of Miami, Miami, FL 33149, United States of America
| | - Martin Grosell
- Department of Marine Biology and Ecology, Rosenstiel School of Marine, Atmospheric, and Earth Science, University of Miami, Miami, FL 33149, United States of America
| |
Collapse
|
3
|
Wood CM, Wang J, Jung EH, Pelster B. The physiological consequences of a very large natural meal in a voracious marine fish, the staghorn sculpin (Leptocottus armatus). J Exp Biol 2023; 226:jeb246034. [PMID: 37675481 DOI: 10.1242/jeb.246034] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2023] [Accepted: 08/26/2023] [Indexed: 09/08/2023]
Abstract
Little information exists on physiological consequences when wild fish eat natural food. Staghorn sculpins at 10-13°C voluntarily consumed 15.8% of their body mass in anchovies. Gastric clearance was slow with >60% of the meal retained in the stomach at 48 h, and was not complete until 84 h. At 14-24 h post-feeding, pH was depressed by 3 units and Cl- concentration was elevated 2-fold in gastric chyme, reflecting HCl secretion, while in all sections of the intestine, pH declined by 1 pH unit but Cl- concentration remained unchanged. PCO2 and total ammonia concentration were greatly elevated throughout the tract, whereas PNH3 and HCO3- concentration were depressed. Intestinal HCO3- secretion rates, measured in gut sacs in vitro, were also lower in fed fish. Whole-animal O2 consumption rate was elevated approximately 2-fold for 72 h post-feeding, reflecting 'specific dynamic action', whereas ammonia and urea-N excretion rates were elevated about 5-fold. Arterial blood exhibited a modest 'alkaline tide' for about 48 h, but there was negligible excretion of metabolic base to the external seawater. PaCO2 and PaO2 remained unchanged. Plasma total amino acid concentration and total lipid concentration were elevated about 1.5-fold for at least 48 h, whereas small increases in plasma total ammonia concentration, PNH3 and urea-N concentration were quickly attenuated. Plasma glucose concentration remained unchanged. We conclude that despite the very large meal, slow processing with high efficiency minimizes internal physiological disturbances. This differs greatly from the picture provided by previous studies on aquacultured species using synthetic diets and/or force-feeding. Questions remain about the role of the gastro-intestinal microbiome in nitrogen and acid-base metabolism.
Collapse
Affiliation(s)
- Chris M Wood
- Department of Zoology, University of British Columbia, Vancouver, BC, Canada, V6T 1Z4
- Bamfield Marine Sciences Centre, Bamfield, BC, Canada, V0R 1B0
- Department of Biology, McMaster University, Hamilton, ON, Canada, L8S 4K1
| | - Jun Wang
- Department of Zoology, University of British Columbia, Vancouver, BC, Canada, V6T 1Z4
- Bamfield Marine Sciences Centre, Bamfield, BC, Canada, V0R 1B0
- College of Marine Life Sciences, Ocean University of China, Qingdao 266003, China
| | - Ellen H Jung
- Department of Zoology, University of British Columbia, Vancouver, BC, Canada, V6T 1Z4
- Bamfield Marine Sciences Centre, Bamfield, BC, Canada, V0R 1B0
| | - Bernd Pelster
- Bamfield Marine Sciences Centre, Bamfield, BC, Canada, V0R 1B0
- Institute of Zoology, University of Innsbruck, 6020 Innsbruck, Austria
- Center for Molecular Biosciences, University Innsbruck, 6020 Innsbruck, Austria
| |
Collapse
|
4
|
Little A, Pasparakis C, Stieglitz J, Grosell M. Metabolic cost of osmoregulation by the gastro-intestinal tract in marine teleost fish. Front Physiol 2023; 14:1163153. [PMID: 37179841 PMCID: PMC10169748 DOI: 10.3389/fphys.2023.1163153] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2023] [Accepted: 04/06/2023] [Indexed: 05/15/2023] Open
Abstract
Introduction: Although dozens of studies have attempted to determine the metabolic cost of osmoregulation, mainly by comparing standard metabolic rates (SMR) in fish acclimated to different salinities, consensus is still lacking. Methods: In the present study, using the Gulf toadfish, Opsanus beta, we aimed to determine the metabolic cost of esophageal and intestinal osmoregulatory processes by estimating ATP consumption from known ion transport rates and pathways and comparing these estimates with measurements on isolated tissues. Further, we performed whole animal respirometry on fish acclimated to 9, 34 and 60 ppt. Results and Discussion: Our theoretical estimates of esophageal and intestinal osmoregulatory costs were in close agreement with direct measurements on isolated tissues and suggest that osmoregulation by these tissues amounts to ∼2.5% of SMR. This value agrees well with an earlier attempt to estimate osmoregulation cost from ion transport rates and combined with published measurements of gill osmoregulatory costs suggests that whole animal costs of osmoregulation in marine teleosts is ∼7.5% of SMR. As in many previous studies, our whole animal measurements were variable between fish and did not seem suited to determine osmoregulatory costs. While the esophagus showed constant metabolic rate regardless of acclimation salinity, the intestine of fish acclimated to higher salinities showed elevated metabolic rates. The esophagus and the intestine had 2.1 and 3.2-fold higher metabolic rates than corresponding whole animal mass specific rates, respectively. The intestinal tissue displays at least four different Cl- uptake pathways of which the Na+:Cl-:2 K+ (NKCC) pathway accounts for 95% of the Cl- uptake and is the most energy efficient. The remaining pathways are via apical anion exchange and seem to primarily serve luminal alkalinization and the formation of intestinal CaCO3 which is essential for water absorption.
Collapse
Affiliation(s)
- A. Little
- University of Miami’s Rosenstiel School of Marine, Atmospheric and Earth Science, Miami, FL, United States
- Department of Biology, McMaster University, Hamilton, ON, Canada
| | - C. Pasparakis
- Bodega Marine Laboratory, University of California Davis, Bodega Bay, CA, United States
| | - J. Stieglitz
- University of Miami’s Rosenstiel School of Marine, Atmospheric and Earth Science, Miami, FL, United States
| | - M. Grosell
- University of Miami’s Rosenstiel School of Marine, Atmospheric and Earth Science, Miami, FL, United States
| |
Collapse
|
5
|
Jung EH, Brauner CJ, Wood CM. Do extreme postprandial levels of oxygen, carbon dioxide, and ammonia in the digestive tract equilibrate with the bloodstream in the freshwater rainbow trout (Oncorhynchus mykiss)? J Comp Physiol B 2023; 193:193-205. [PMID: 36656334 DOI: 10.1007/s00360-023-01475-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2022] [Revised: 12/20/2022] [Accepted: 01/06/2023] [Indexed: 01/20/2023]
Abstract
The gastrointestinal tract (GIT) lumen of teleosts harbors extreme conditions, especially after feeding: high PCO2 (20-115 Torr), total ammonia (415-3710 μM), PNH3 (79-1760 μTorr in the intestine), and virtual anoxia (PO2 < 1 Torr). These levels could be dangerous if they were to equilibrate with the bloodstream. Thus, we investigated the potential equilibration of O2, CO2, and ammonia across the GIT epithelia in freshwater rainbow trout by monitoring postprandial arterial and venous blood gases in vivo and in situ. In vivo blood was sampled from the indwelling catheters in the dorsal aorta (DA) and subintestinal vein (SIV) draining the posterior intestine in the fasting state and at 4 to 48 h following catheter-feeding. To investigate possible ammonia absorption in the anterior part of the GIT, blood was sampled from the DA, SIV and hepatic portal vein (HPV) from anaesthetized fish in situ following voluntary feeding. We found minimal equilibration of all three gases between the GIT lumen and the SIV blood, with the latter maintaining pre-feeding levels (PO2 = 25-49 Torr, PCO2 = 6-8 Torr, and total ammonia = 117-134 μM and PNH3 = 13-30 μTorr at 48 h post-feeding). In contrast to the SIV, we found that the HPV total ammonia more than doubled 24 h after feeding (128 to 297 μM), indicative of absorption in the anterior GIT. Overall, the GIT epithelia of trout, although specialized for absorption, prevent dangerous levels of PO2, PCO2 and ammonia from equilibrating with the blood circulation.
Collapse
Affiliation(s)
- Ellen H Jung
- Department of Zoology, University of British Columbia, Vancouver, BC, V6T 1Z4, Canada.
| | - Colin J Brauner
- Department of Zoology, University of British Columbia, Vancouver, BC, V6T 1Z4, Canada
| | - Chris M Wood
- Department of Zoology, University of British Columbia, Vancouver, BC, V6T 1Z4, Canada
| |
Collapse
|
6
|
Ghilardi M, Salter MA, Parravicini V, Ferse SCA, Rixen T, Wild C, Birkicht M, Perry CT, Berry A, Wilson RW, Mouillot D, Bejarano S. Temperature, species identity and morphological traits predict carbonate excretion and mineralogy in tropical reef fishes. Nat Commun 2023; 14:985. [PMID: 36813767 PMCID: PMC9947118 DOI: 10.1038/s41467-023-36617-7] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2022] [Accepted: 02/08/2023] [Indexed: 02/24/2023] Open
Abstract
Anthropogenic pressures are restructuring coral reefs globally. Sound predictions of the expected changes in key reef functions require adequate knowledge of their drivers. Here we investigate the determinants of a poorly-studied yet relevant biogeochemical function sustained by marine bony fishes: the excretion of intestinal carbonates. Compiling carbonate excretion rates and mineralogical composition from 382 individual coral reef fishes (85 species and 35 families), we identify the environmental factors and fish traits that predict them. We find that body mass and relative intestinal length (RIL) are the strongest predictors of carbonate excretion. Larger fishes and those with longer intestines excrete disproportionately less carbonate per unit mass than smaller fishes and those with shorter intestines. The mineralogical composition of excreted carbonates is highly conserved within families, but also controlled by RIL and temperature. These results fundamentally advance our understanding of the role of fishes in inorganic carbon cycling and how this contribution will change as community composition shifts under increasing anthropogenic pressures.
Collapse
Affiliation(s)
- Mattia Ghilardi
- Leibniz Centre for Tropical Marine Research (ZMT), Fahrenheitstraße 6, 28359, Bremen, Germany. .,Department of Marine Ecology, Faculty of Biology and Chemistry, University of Bremen, Leobener Straße UFT, 28359, Bremen, Germany.
| | | | - Valeriano Parravicini
- PSL Université Paris: EPHE-UPVD-CNRS, USR3278 CRIOBE, University of Perpignan, 66860, Perpignan, France.,Institut Universitaire de France, Paris, France
| | - Sebastian C A Ferse
- Leibniz Centre for Tropical Marine Research (ZMT), Fahrenheitstraße 6, 28359, Bremen, Germany.,Department of Marine Ecology, Faculty of Biology and Chemistry, University of Bremen, Leobener Straße UFT, 28359, Bremen, Germany
| | - Tim Rixen
- Leibniz Centre for Tropical Marine Research (ZMT), Fahrenheitstraße 6, 28359, Bremen, Germany
| | - Christian Wild
- Department of Marine Ecology, Faculty of Biology and Chemistry, University of Bremen, Leobener Straße UFT, 28359, Bremen, Germany
| | - Matthias Birkicht
- Leibniz Centre for Tropical Marine Research (ZMT), Fahrenheitstraße 6, 28359, Bremen, Germany
| | - Chris T Perry
- Geography, University of Exeter, Exeter, EX4 4RJ, UK
| | - Alex Berry
- Biosciences, University of Exeter, Exeter, EX4 4QD, UK
| | - Rod W Wilson
- Biosciences, University of Exeter, Exeter, EX4 4QD, UK
| | - David Mouillot
- Institut Universitaire de France, Paris, France.,MARBEC, Univ Montpellier, CNRS, Ifremer, IRD, 34095, Montpellier, France
| | - Sonia Bejarano
- Leibniz Centre for Tropical Marine Research (ZMT), Fahrenheitstraße 6, 28359, Bremen, Germany
| |
Collapse
|
7
|
Entrena-Barbero E, Feijoo G, González-García S, Moreira MT. Blue carbon accounting as metrics to be taken into account towards the target of GHG emissions mitigation in fisheries. THE SCIENCE OF THE TOTAL ENVIRONMENT 2022; 847:157558. [PMID: 35901881 DOI: 10.1016/j.scitotenv.2022.157558] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/07/2022] [Revised: 06/21/2022] [Accepted: 07/18/2022] [Indexed: 06/15/2023]
Abstract
The adoption of the 2030 Agenda for Sustainable Development must address the balance between sustainable growth and tackling climate change. In this context, forests can help to reduce greenhouse gas (GHG) emissions, unfortunately, equivalent solutions in the ocean are often overlooked. Moreover, the complexity in determining the real impact of fishing on the environment is not a trivial issue. Thus, the aim of this study is to broaden the scope and analyse, for the first time, the entire carbon cycle associated with the life cycle of a fish: Scomber scombrus from a fishery located in the Cantabrian Sea (Spain). From this carbon cycle assessment, it is estimated that fishing activity has prevented 871.7 t of carbon (in terms of blue carbon) from being sequestered each year. This value comes from the fraction of fish that would have died of natural causes if they had not been caught, reaching the seabed, and undergoing remineralisation processes of the carbon content of their bodies. Beyond these results, it is vital to implement a series of actions with the aim of counteracting the amount of carbon that could have been sequestered on the seabed by the natural death of the fishes if they had not been caught. To this end, it is shown that the implementation of technical improvements to the vessels, the replacement of the current fuel used and the rearrangement of shipping routes in combination with an extension in the closed fishing season and a commitment to an omnivorous diet, allows for a reduction in carbon flow of almost 90 % of the blue carbon that has been prevented from being sequestered by fisheries. A consequential approach can then identify the influence of the proposed changes on their corresponding carbon flows for use as decision criteria in regulating fisheries and environmental management policies.
Collapse
Affiliation(s)
- Eduardo Entrena-Barbero
- CRETUS, Department of Chemical Engineering, School of Engineering, Universidade de Santiago de Compostela, 15782 Santiago de Compostela, Spain.
| | - Gumersindo Feijoo
- CRETUS, Department of Chemical Engineering, School of Engineering, Universidade de Santiago de Compostela, 15782 Santiago de Compostela, Spain
| | - Sara González-García
- CRETUS, Department of Chemical Engineering, School of Engineering, Universidade de Santiago de Compostela, 15782 Santiago de Compostela, Spain
| | - María Teresa Moreira
- CRETUS, Department of Chemical Engineering, School of Engineering, Universidade de Santiago de Compostela, 15782 Santiago de Compostela, Spain
| |
Collapse
|
8
|
Yarlett RT, Perry CT, Wilson RW. Quantifying production rates and size fractions of parrotfish-derived sediment: A key functional role on Maldivian coral reefs. Ecol Evol 2021; 11:16250-16265. [PMID: 34824825 PMCID: PMC8601892 DOI: 10.1002/ece3.8306] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2021] [Revised: 09/13/2021] [Accepted: 10/15/2021] [Indexed: 11/11/2022] Open
Abstract
Coral reef fish perform numerous important functional roles on coral reefs. Of these, carbonate sediment production, as a by-product of parrotfish feeding, is especially important for contributing to reef framework construction and reef-associated landform development. However, only limited data exist on: (i) how production rates vary among reef habitats as a function of parrotfish assemblages, (ii) the relative importance of sediment produced from eroded, reworked, and endogenous sources, or (iii) the size fractions of sediment generated by different parrotfish species and size classes. These parameters influence not only overall reef-derived sediment supply, but also influence the transport potential and depositional fate of this sedimentary material. Here, we show that parrotfish sediment production varies significantly between reef-platform habitats on an atoll-margin Maldivian reef. Highest rates of production (over 0.8 kg m-2 year-1) were calculated in three of the eight platform habitats; a rubble-dominated zone, an Acropora spp. dominated zone, and a patch reef zone. Habitat spatial extent and differences in associated parrotfish assemblages strongly influenced the total quantities of sediment generated within each habitat. Nearly half of total parrotfish sediment production occurred in the rubble habitat, which comprised only 8% of the total platform area. Over 90% of this sedimentary material originated from eroded reef framework as opposed to being reworked existing or endogenously produced sediment, and comprised predominantly coral sands (predominantly 125-1000 µm in diameter). This is comparable to the dominant sand types and size fractions found on Maldivian reef islands. By contrast, nearly half of the sediment egested by parrotfish in the Acropora spp. dominated and patch reef habitats resulted from reworked existing sediments. These differences between habitats are a result of the different parrotfish assemblages supported. Endogenous carbonate production was found to be insignificant compared to the quantity of eroded and reworked material. Our findings have important implications for identifying key habitats and species which act as major sources of sediment for reef-island systems.
Collapse
Affiliation(s)
- Robert T. Yarlett
- GeographyCollege of Life and Environmental SciencesUniversity of ExeterExeterUK
| | - Chris T. Perry
- GeographyCollege of Life and Environmental SciencesUniversity of ExeterExeterUK
| | - Rod W. Wilson
- BiosciencesCollege of Life and Environmental SciencesUniversity of ExeterExeterUK
| |
Collapse
|
9
|
Takei Y. The digestive tract as an essential organ for water acquisition in marine teleosts: lessons from euryhaline eels. ZOOLOGICAL LETTERS 2021; 7:10. [PMID: 34154668 PMCID: PMC8215749 DOI: 10.1186/s40851-021-00175-x] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/02/2020] [Accepted: 04/16/2021] [Indexed: 05/17/2023]
Abstract
Adaptation to a hypertonic marine environment is one of the major topics in animal physiology research. Marine teleosts lose water osmotically from the gills and compensate for this loss by drinking surrounding seawater and absorbing water from the intestine. This situation is in contrast to that in mammals, which experience a net osmotic loss of water after drinking seawater. Water absorption in fishes is made possible by (1) removal of monovalent ions (desalinization) by the esophagus, (2) removal of divalent ions as carbonate (Mg/CaCO3) precipitates promoted by HCO3- secretion, and (3) facilitation of NaCl and water absorption from diluted seawater by the intestine using a suite of unique transporters. As a result, 70-85% of ingested seawater is absorbed during its passage through the digestive tract. Thus, the digestive tract is an essential organ for marine teleost survival in the hypertonic seawater environment. The eel is a species that has been frequently used for osmoregulation research in laboratories worldwide. The eel possesses many advantages as an experimental animal for osmoregulation studies, one of which is its outstanding euryhalinity, which enables researchers to examine changes in the structure and function of the digestive tract after direct transfer from freshwater to seawater. In recent years, the molecular mechanisms of ion and water transport across epithelial cells (the transcellular route) and through tight junctions (the paracellular route) have been elucidated for the esophagus and intestine. Thanks to the rapid progress in analytical methods for genome databases on teleosts, including the eel, the molecular identities of transporters, channels, pumps and junctional proteins have been clarified at the isoform level. As 10 y have passed since the previous reviews on this subject, it seems relevant and timely to summarize recent progress in research on the molecular mechanisms of water and ion transport in the digestive tract in eels and to compare the mechanisms with those of other teleosts and mammals from comparative and evolutionary viewpoints. We also propose future directions for this research field to achieve integrative understanding of the role of the digestive tract in adaptation to seawater with regard to pathways/mechanisms including the paracellular route, divalent ion absorption, metabolon formation and cellular trafficking of transporters. Notably, some of these have already attracted practical attention in laboratories.
Collapse
Affiliation(s)
- Yoshio Takei
- Laboratory of Physiology, Department of Marine Bioscience, Atmosphere and Ocean Research Institute, The University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba, 277-8564, Japan.
| |
Collapse
|
10
|
Goodrich HR, Bayley M, Birgersson L, Davison WG, Johannsson OE, Kim AB, Le My P, Tinh TH, Thanh PN, Thanh HDT, Wood CM. Understanding the gastrointestinal physiology and responses to feeding in air-breathing Anabantiform fishes. JOURNAL OF FISH BIOLOGY 2020; 96:986-1003. [PMID: 32060920 DOI: 10.1111/jfb.14288] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/09/2019] [Revised: 12/16/2019] [Accepted: 02/13/2020] [Indexed: 06/10/2023]
Abstract
The Mekong Delta is host to a large number of freshwater species, including a unique group of facultative air-breathing Anabantiforms. Of these, the striped snakehead (Channa striata), the climbing perch (Anabas testudineus), the giant gourami (Osphronemus goramy) and the snakeskin gourami (Trichogaster pectoralis) are major contributors to aquaculture production in Vietnam. The gastrointestinal responses to feeding in these four species are detailed here. Relative intestinal length was lowest in the snakehead, indicating carnivory, and 5.5-fold greater in the snakeskin, indicating herbivory; climbing perch and giant gourami were intermediate, indicating omnivory. N-waste excretion (ammonia-N + urea-N) was greatest in the carnivorous snakehead and least in the herbivorous snakeskin, whereas the opposite trend was observed for net K+ excretion. Similarly, the more carnivorous species had a greater stomach acidity than the more herbivorous species. Measurements of acid-base flux to water indicated that the greatest postprandial alkaline tide occurred in the snakehead and a potential acidic tide in the snakeskin. Additional findings of interest were high levels of both PCO2 (up to 40 mmHg) and HCO3 - (up to 33 mM) in the intestinal chyme of all four of these air-breathing species. Using in vitro gut sac preparations of the climbing perch, it was shown that the intestinal net absorption of fluid, Na+ and HCO3 - was upregulated by feeding but not net Cl- uptake, glucose uptake or K+ secretion. Upregulated net absorption of HCO3 - suggests that the high chyme (HCO3 - ) does not result from secretion by the intestinal epithelium. The possibility of ventilatory control of PCO2 to regulate postprandial acid-base balance in these air-breathing fish is discussed.
Collapse
Affiliation(s)
- Harriet R Goodrich
- School of Biological Sciences, The University of Queensland, St Lucia, QLD, Australia
- College of Life and Environmental Sciences, The University of Exeter, Exeter, Devon, UK
| | - Mark Bayley
- Department of Bioscience, Zoophysiology Aarhus University, Aarhus, Denmark
| | - Lina Birgersson
- Department of Biological and Environmental Sciences, University of Gothenburg, Göteborg, Sweden
| | - William G Davison
- College of Life and Environmental Sciences, The University of Exeter, Exeter, Devon, UK
| | - Ora E Johannsson
- Department of Zoology, University of British Columbia, Vancouver, BC, Canada
| | - Anne B Kim
- Department of Zoology, University of British Columbia, Vancouver, BC, Canada
| | - Phuong Le My
- Department of Agriculture, Bac Lieu University, Bac Lieu, Vietnam
| | - Tran H Tinh
- Aquaculture and Fisheries, Department of Animal Sciences, Wageningen University and Research, Wageningen, The Netherlands
| | - Phuong N Thanh
- College of Aquaculture and Fisheries, Can Tho University, Cần Thơ, Vietnam
| | - Huong Do Thi Thanh
- College of Aquaculture and Fisheries, Can Tho University, Cần Thơ, Vietnam
| | - Chris M Wood
- Department of Zoology, University of British Columbia, Vancouver, BC, Canada
| |
Collapse
|
11
|
Wood CM, Eom J. The internal CO 2 threat to fish: high PCO 2 in the digestive tract. Proc Biol Sci 2019; 286:20190832. [PMID: 31311467 DOI: 10.1098/rspb.2019.0832] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Our goal was to use novel fibreoptic sensors to make the first direct PCO2 measurements in the digestive tracts of live freshwater fish (anaesthetized, artificially ventilated, 12°C). PCO2 levels in gastrointestinal fluids were substantially higher than in blood, and were elevated after feeding. In the carnivorous, gastric rainbow trout, the mean PCO2 in various parts of the tract increased from 7-13 torr (1 torr = 0.1333 kPa) during fasting to 20-41 torr after feeding, relative to arterial levels of 3.5-4 torr. In the agastric, omnivorous goldfish, the mean gut levels varied from 10-13 torr in fasted animals to 14-18 torr in fed animals, relative to arterial levels of 5-7 torr. These elevated PCO2 values were associated with surprisingly high [Formula: see text] concentrations (greater than 40 mmol l-1) in the intestinal chyme. Incubations of food pellets with acid or water revealed endogenous PCO2 generation sufficient to explain gastric PCO2 in fed trout and anterior intestine PCO2 in fed goldfish. The impacts of possible equilibration with venous blood draining the tract are assessed. We conclude that fish are already coping with PCO2 levels in the internal gastrointestinal environment many-fold greater than those of current concern in the external environment for climate change and aquacultural scenarios.
Collapse
Affiliation(s)
- Chris M Wood
- Department of Zoology, University of British Columbia, Vancouver, British Columbia, Canada V6T 1Z4
| | - Junho Eom
- Department of Zoology, University of British Columbia, Vancouver, British Columbia, Canada V6T 1Z4
| |
Collapse
|
12
|
Gregório SF, Ruiz-Jarabo I, Carvalho EM, Fuentes J. Increased intestinal carbonate precipitate abundance in the sea bream (Sparus aurata L.) in response to ocean acidification. PLoS One 2019; 14:e0218473. [PMID: 31226164 PMCID: PMC6588277 DOI: 10.1371/journal.pone.0218473] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2019] [Accepted: 06/03/2019] [Indexed: 12/20/2022] Open
Abstract
Marine fish contribute to the carbon cycle by producing mineralized intestinal precipitates generated as by-products of their osmoregulation. Here we aimed at characterizing the control of epithelial bicarbonate secretion and intestinal precipitate presence in the gilthead sea bream in response to predicted near future increases of environmental CO2. Our results demonstrate that hypercapnia (950 and 1800 μatm CO2) elicits higher intestine epithelial HCO3- secretion ex vivo and a subsequent parallel increase of intestinal precipitate presence in vivo when compared to present values (440 μatm CO2). Intestinal gene expression analysis in response to environmental hypercapnia revealed the up-regulation of transporters involved in the intestinal bicarbonate secretion cascade such as the basolateral sodium bicarbonate co-transporter slc4a4, and the apical anion transporters slc26a3 and slc26a6 of sea bream. In addition, other genes involved in intestinal ion uptake linked to water absorption such as the apical nkcc2 and aquaporin 1b expression, indicating that hypercapnia influences different levels of intestinal physiology. Taken together the current results are consistent with an intestinal physiological response leading to higher bicarbonate secretion in the intestine of the sea bream paralleled by increased luminal carbonate precipitate abundance and the main related transporters in response to ocean acidification.
Collapse
Affiliation(s)
- Sílvia F. Gregório
- Centre of Marine Sciences (CCMar), Universidade do Algarve, Campus de Gambelas, Faro, Portugal
| | - Ignacio Ruiz-Jarabo
- Centre of Marine Sciences (CCMar), Universidade do Algarve, Campus de Gambelas, Faro, Portugal
| | - Edison M. Carvalho
- Centre of Marine Sciences (CCMar), Universidade do Algarve, Campus de Gambelas, Faro, Portugal
| | - Juan Fuentes
- Centre of Marine Sciences (CCMar), Universidade do Algarve, Campus de Gambelas, Faro, Portugal
- * E-mail:
| |
Collapse
|
13
|
Williams M, Barranca D, Bucking C. Zonation of Ca 2+ transport and enzyme activity in the caeca of rainbow trout - a simple structure with complex functions. ACTA ACUST UNITED AC 2019; 222:jeb.187484. [PMID: 30765468 DOI: 10.1242/jeb.187484] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2018] [Accepted: 02/07/2019] [Indexed: 11/20/2022]
Abstract
Trout caeca are vermiform structures projecting from the anterior intestine of the gastrointestinal tract. Despite their simple gross morphology, these appendages are physically distinct along the anterior-posterior axis, and ultrastructural evidence suggests zonation of function within the structures. Individual caeca from three sections (anterior, middle and posterior) were removed from the intestine of freshwater rainbow trout and investigated for ion transport and enzyme activity. Ca2+ absorption appeared as a combination of active and passive movement, with Michaelis-Menten kinetics observable under symmetrical conditions, and was inhibited by several pharmacological agents (ouabain, La3+ and a calmodulin antagonist). There was a decrease in ion transport function from adjacent to the intestine (proximal) to the distal tip of each caecum, along with decreasing transport from anterior to posterior for the proximal portion alone. Feeding increased the J Max and K M for Ca2+ absorption within all sections, whereas ion-poor water (IPW) exposure further increased the J Max and K M for Ca2+ transport in the anterior and middle sections. Increased Na+/K+-ATPase (NKA) and citrate synthase (CS) activity rates paralleled trends seen in Ca2+ transport. Feeding in freshwater and IPW exposure increased the glycolytic capacity of the caeca via increased pyruvate kinase (PK) and decreased lactate dehydrogenase (LDH) activity, while amino acid metabolism increased with IPW exposure through increased glutamate dehydrogenase (GDH) activity. Overall, feeding and IPW exposure each altered ionoregulation within the caeca of freshwater rainbow trout in a zone-specific pattern, with the anterior and proximal portions of the caeca being most affected. Increased carbohydrate and protein metabolism fueled the increased ATP demand of NKA through CS.
Collapse
Affiliation(s)
- Melanie Williams
- Department of Biology, York University, Toronto, Ontario, Canada, M3J 1P3
| | - Domenico Barranca
- Department of Biology, York University, Toronto, Ontario, Canada, M3J 1P3
| | - Carol Bucking
- Department of Biology, York University, Toronto, Ontario, Canada, M3J 1P3
| |
Collapse
|
14
|
Brauner CJ, Shartau RB, Damsgaard C, Esbaugh AJ, Wilson RW, Grosell M. Acid-base physiology and CO2 homeostasis: Regulation and compensation in response to elevated environmental CO2. FISH PHYSIOLOGY 2019. [DOI: 10.1016/bs.fp.2019.08.003] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
|
15
|
Gregório SF, Fuentes J. Regulation of Bicarbonate Secretion in Marine Fish Intestine by the Calcium-Sensing Receptor. Int J Mol Sci 2018; 19:E1072. [PMID: 29617283 PMCID: PMC5979614 DOI: 10.3390/ijms19041072] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2017] [Revised: 03/26/2018] [Accepted: 04/01/2018] [Indexed: 12/29/2022] Open
Abstract
In marine fish, high epithelial intestinal HCO₃− secretion generates luminal carbonate precipitates of divalent cations that play a key role in water and ion homeostasis. The present study was designed to expose the putative role for calcium and the calcium-sensing receptor (CaSR) in the regulation of HCO₃− secretion in the intestine of the sea bream (Sparus aurata L.). Effects on the expression of the CaSR in the intestine were evaluated by qPCR and an increase was observed in the anterior intestine in fed fish compared with unfed fish and with different regions of intestine. CaSR expression reflected intestinal fluid calcium concentration. In addition, anterior intestine tissue was mounted in Ussing chambers to test the putative regulation of HCO₃− secretion in vitro using the anterior intestine. HCO₃− secretion was sensitive to varying calcium levels in luminal saline and to calcimimetic compounds known to activate/block the CaSR i.e., R 568 and NPS-2143. Subsequent experiments were performed in intestinal sacs to measure water absorption and the sensitivity of water absorption to varying luminal levels of calcium and calcimimetics were exposed as well. It appears, that CaSR mediates HCO₃− secretion and water absorption in marine fish as shown by responsiveness to calcium levels and calcimimetic compounds.
Collapse
Affiliation(s)
- Sílvia F Gregório
- Centre of Marine Sciences (CCMar), Universidade do Algarve, Campus de Gambelas, 8005-139 Faro, Portugal.
| | - Juan Fuentes
- Centre of Marine Sciences (CCMar), Universidade do Algarve, Campus de Gambelas, 8005-139 Faro, Portugal.
| |
Collapse
|
16
|
Esbaugh AJ, Cutler B. Intestinal Na+, K+, 2Cl- cotransporter 2 plays a crucial role in hyperosmotic transitions of a euryhaline teleost. Physiol Rep 2017; 4:4/22/e13028. [PMID: 27881573 PMCID: PMC5358003 DOI: 10.14814/phy2.13028] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2016] [Revised: 10/06/2016] [Accepted: 10/07/2016] [Indexed: 11/29/2022] Open
Abstract
Euryhaline fishes, such as the red drum (Sciaenops ocellatus), must quickly transition between hyperosmotic and hypoosmotic physiological strategies. When freshwater individuals transition to seawater they are exposed to increased diffusive water loss and ion gain. To maintain osmoregulatory balance these animals must drink and absorb seawater through the intestine, followed by ion excretion at the gills. The ability of fishes to transition between strategies can limit the magnitude of osmotic shock that can be tolerated. Here, we demonstrate that red drum can tolerate direct transfer from freshwater to full‐strength seawater with marginal impacts on osmotic balance, as indicated by plasma and muscle ion concentration, as well as muscle water. Seawater transition is concurrent with a significant increase in intestinal fluid volume. Typical patterns of osmoregulatory plasticity were observed in the gill with increased expression of nkcc1 and cftr. Expression changes in the anterior intestine were observed after 24 h for nkcc2 with smaller and later responses observed for slc26a3, slc26a6, and nbc. Immunofluorescence staining demonstrated similar patterns of NKCC localization in freshwater and seawater intestines; however, reduced basolateral staining of V‐type ATPase was observed in seawater. Electrophysiological preparations demonstrated that seawater fish had increased absorptive current in the anterior intestine, which was significantly reduced in the presence of 10 μmol/L bumetanide. Overall, these results suggest that nkcc2 plays a crucial role during hyperosmotic transitions, and may be a more important complement to the well‐known bicarbonate secretion pathway than generally considered.
Collapse
Affiliation(s)
- Andrew J Esbaugh
- University of Texas at Austin Marine Science Institute, Austin, Texas
| | - Brett Cutler
- University of Texas at Austin Marine Science Institute, Austin, Texas
| |
Collapse
|
17
|
Similarity of osmoregulatory capacity in coastal and inland alligator gar. Comp Biochem Physiol A Mol Integr Physiol 2017; 209:16-24. [PMID: 28400249 DOI: 10.1016/j.cbpa.2017.04.003] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2016] [Revised: 04/05/2017] [Accepted: 04/05/2017] [Indexed: 11/24/2022]
Abstract
The alligator gar Atractosteus spatula is a primitive fish species, occupying a wide range of temperature and salinity habitats. Long-distance movements are limited, leading to genetic differentiation between inland and coastal populations. Unknown is whether physiological capacity differs between geographically separated populations, particularly for traits important to osmoregulation in saline environments. Alligator gar from inland and coastal populations were reared in a similar environment and exposed to temperature (10, 30°C) and salinity (0, 20ppt) extremes to determine whether iono- and osmoregulatory ability differed between populations. There were few differences in osmoregulatory ability between populations, with similar gill, blood and gastrointestinal tract osmoregulatory parameters. Blood plasma osmolality, ion concentrations, intestinal pH and bicarbonate base concentrations, intestinal fluid osmolality, ion concentrations and gill Na+, K+-ATPase (NKA) activity were similar between populations. Notably, gar from both populations did not osmoregulate well at low temperature and high salinity, with elevated plasma osmolality and ion concentrations, low gill NKA, and little evidence of gastrointestinal tract contribution to ionic and base regulation based on a lack of intestinal fluid and low base content. Therefore, the hypothesis that coastal gar would have improved osmotic regulatory ability in saline environments as compared to inland alligator gar was not supported, suggesting physiological capacity may be retained in primitive species possibly due to its importance to their persistence through time.
Collapse
|
18
|
Dietary electrolyte balance affects growth performance, amylase activity and metabolic response in the meagre (Argyrosomus regius). Comp Biochem Physiol B Biochem Mol Biol 2017; 211:8-15. [PMID: 28323073 DOI: 10.1016/j.cbpb.2017.03.001] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2016] [Revised: 03/10/2017] [Accepted: 03/10/2017] [Indexed: 12/30/2022]
Abstract
Dietary ion content is known to alter the acid-base balance in freshwater fish. The current study investigated the metabolic impact of acid-base disturbances produced by differences in dietary electrolyte balance (DEB) in the meagre (Argyrosomus regius), an euryhaline species. Changes in fish performance, gastric chyme characteristics, pH and ion concentrations in the bloodstream, digestive enzyme activities and metabolic rates were analyzed in meagre fed ad libitum two experimental diets (DEB 200 or DEB 700mEq/kg) differing in the Na2CO3 content for 69days. Fish fed the DEB 200 diet had 60-66% better growth performance than the DEB 700 group. Meagre consuming the DEB 200 diet were 90-96% more efficient than fish fed the DEB 700 diet at allocating energy from feed into somatic growth. The pH values in blood were significantly lower in the DEB 700 group 2h after feeding when compared to DEB 200, indicating that acid-base balance in meagre was affected by electrolyte balance in diet. Osmolality, and Na+ and K+ concentrations in plasma did not vary with the dietary treatment. Gastric chyme in the DEB 700 group had higher pH values, dry matter, protein and energy contents, but lower lipid content than in the DEB 200 group. Twenty-four hours after feeding, amylase activity was higher in the gastrointestinal tract of DEB 700 group when compared to the DEB 200 group. DEB 700 group had lower routine metabolic (RMR) and standard metabolic (SMR) rates, indicating a decrease in maintenance energy expenditure 48h after feeding the alkaline diet. The current study demonstrates that feeding meagre with an alkaline diet not only causes acid-base imbalance, but also negatively affects digestion and possibly nutrient assimilation, resulting in decreased growth performance.
Collapse
|
19
|
Ruiz-Jarabo I, Gregório SF, Gaetano P, Trischitta F, Fuentes J. High rates of intestinal bicarbonate secretion in seawater tilapia (Oreochromis mossambicus). Comp Biochem Physiol A Mol Integr Physiol 2017; 207:57-64. [PMID: 28238831 DOI: 10.1016/j.cbpa.2017.02.022] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2016] [Revised: 02/13/2017] [Accepted: 02/20/2017] [Indexed: 01/07/2023]
Abstract
Osmoregulation in fish is a complex process that requires the orchestrated cooperation of many tissues. In fish facing hyperosmotic environments, the intestinal absorption of some monovalent ions and the secretion of bicarbonate are key processes to favor water absorption. In the present study, we showed that bicarbonate levels in the intestinal fluid are several fold higher in seawater than in freshwater acclimated tilapia (Oreochromis mossambicus). In addition, we analyzed gene expression of the main molecular mechanisms involved in HCO3- movements i.e. slc26a6, slc26a3, slc4a4 and v-type H-ATPase sub C in the intestine of tilapia acclimated to both seawater and freshwater. Our results show an anterior/posterior functional regionalization of the intestine in tilapia in terms of expression patterns, which is affected by environmental salinity mostly in the anterior and mid intestine. Analysis of bicarbonate secretion using pH-Stat in tissues mounted in Ussing chambers reveals high rates of bicarbonate secretion in tilapia acclimated to seawater from anterior intestine to rectum ranging between ~900 and ~1700nmolHCO3-cm-2h-1. However, a relationship between the expression of slc26a6, slc26a3, slc4a4 and the rate of bicarbonate secretion seems to be compromised in the rectum. In this region, the low expression of the bicarbonate transporters could not explain the high bicarbonate secretion rates here described. However, we postulate that the elevated v-type H-ATPase mRNA expression in the rectum could be involved in this process.
Collapse
Affiliation(s)
- I Ruiz-Jarabo
- Comparative Endocrinology and Integrative Biology, Centre of Marine Sciences (CCMar), Universidade do Algarve, Campus de Gambelas, 8005-139 Faro, Portugal
| | - S F Gregório
- Comparative Endocrinology and Integrative Biology, Centre of Marine Sciences (CCMar), Universidade do Algarve, Campus de Gambelas, 8005-139 Faro, Portugal
| | - P Gaetano
- Comparative Endocrinology and Integrative Biology, Centre of Marine Sciences (CCMar), Universidade do Algarve, Campus de Gambelas, 8005-139 Faro, Portugal; Dipartimento di Scienze Chimiche, Biologiche, Farmaceutiche ed Ambientali, Università degli Studi di Messina, Messina, Italy
| | - F Trischitta
- Dipartimento di Scienze Chimiche, Biologiche, Farmaceutiche ed Ambientali, Università degli Studi di Messina, Messina, Italy
| | - J Fuentes
- Comparative Endocrinology and Integrative Biology, Centre of Marine Sciences (CCMar), Universidade do Algarve, Campus de Gambelas, 8005-139 Faro, Portugal.
| |
Collapse
|
20
|
Ruiz-Jarabo I, Barany A, Jerez-Cepa I, Mancera JM, Fuentes J. Intestinal response to salinity challenge in the Senegalese sole (Solea senegalensis). Comp Biochem Physiol A Mol Integr Physiol 2016; 204:57-64. [PMID: 27865855 DOI: 10.1016/j.cbpa.2016.11.009] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2016] [Revised: 09/08/2016] [Accepted: 11/14/2016] [Indexed: 12/27/2022]
Abstract
Fish are continuously forced to actively absorb or expel water and ions through epithelia. Most studies have focused on the gill due to its role in Na+ and Cl- trafficking. However, comparatively few studies have focused on the changing function of the intestine in response to external salinity. Therefore, the present study investigated the main intestinal changes of long-term acclimation of the Senegalese sole (Solea senegalensis) to 5, 15, 38 and 55ppt. Through the measurement of short-circuit current (Isc) in Ussing chambers and biochemical approaches, we described a clear anterior/posterior functional regionalization of the intestine in response to salinity. The use of specific inhibitors in Ussing chamber experiments, revealed that the bumetanide-sensitive Na+/K+/Cl- co-transporters are the main effectors of Cl- uptake in both anterior intestine and rectum. Additionally, the use of the anion exchanger specific inhibitor, DIDS, showed a salinity/region dependency of anion exchanger function. Moreover, we also described ouabain-sensitive Na+/K+-ATPase (NKA) and Bafilomycin A1-sensitive H+-ATPase activities (HA), which displayed changes related to salinity and intestinal region. However, the most striking result of the present study is the description of an omeprazole-sensitive H+/K+-ATPase (HKA) in the rectum of Senegalese sole. Its activity was consistently measurable and increased at lower salinities, reaching rates even higher than those of the NKA. Together our results provide new insights into the changing role of the intestine in response to external salinity in teleost fish. The rectal activity of HKA offers an alternative/cooperative mechanism with the HA in the final processing of intestinal water absorption by apical titration of secreted bicarbonate.
Collapse
Affiliation(s)
- I Ruiz-Jarabo
- Comparative Endocrinology and Integrative Biology, Centre of Marine Sciences (CCMar), Universidade do Algarve, Campus de Gambelas, 8005-139 Faro, Portugal; Departamento de Biología, Facultad de Ciencias del Mar y Ambientales, Universidad de Cádiz, 11510, Puerto Real, Cádiz, Spain
| | - A Barany
- Comparative Endocrinology and Integrative Biology, Centre of Marine Sciences (CCMar), Universidade do Algarve, Campus de Gambelas, 8005-139 Faro, Portugal; Departamento de Biología, Facultad de Ciencias del Mar y Ambientales, Universidad de Cádiz, 11510, Puerto Real, Cádiz, Spain
| | - I Jerez-Cepa
- Departamento de Biología, Facultad de Ciencias del Mar y Ambientales, Universidad de Cádiz, 11510, Puerto Real, Cádiz, Spain
| | - J M Mancera
- Departamento de Biología, Facultad de Ciencias del Mar y Ambientales, Universidad de Cádiz, 11510, Puerto Real, Cádiz, Spain
| | - J Fuentes
- Comparative Endocrinology and Integrative Biology, Centre of Marine Sciences (CCMar), Universidade do Algarve, Campus de Gambelas, 8005-139 Faro, Portugal.
| |
Collapse
|
21
|
Schauer KL, LeMoine CMR, Pelin A, Corradi N, Warren WC, Grosell M, McDonald MD. A proteinaceous organic matrix regulates carbonate mineral production in the marine teleost intestine. Sci Rep 2016; 6:34494. [PMID: 27694946 PMCID: PMC5046086 DOI: 10.1038/srep34494] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2016] [Accepted: 09/14/2016] [Indexed: 12/24/2022] Open
Abstract
Marine teleost fish produce CaCO3 in their intestine as part of their osmoregulatory strategy. This precipitation is critical for rehydration and survival of the largest vertebrate group on earth, yet the molecular mechanisms that regulate this reaction are unknown. Here, we isolate and characterize an organic matrix associated with the intestinal precipitates produced by Gulf toadfish (Opsanus beta). Toadfish precipitates were purified using two different methods, and the associated organic matrix was extracted. Greater than 150 proteins were identified in the isolated matrix by mass spectrometry and subsequent database searching using an O. beta transcriptomic sequence library produced here. Many of the identified proteins were enriched in the matrix compared to the intestinal fluid, and three showed no substantial homology to any previously characterized protein in the NCBI database. To test the functionality of the isolated matrix, a micro-modified in vitro calcification assay was designed, which revealed that low concentrations of isolated matrix substantially promoted CaCO3 production, where high concentrations showed an inhibitory effect. High concentrations of matrix also decreased the incorporation of magnesium into the forming mineral, potentially providing an explanation for the variability in magnesium content observed in precipitates produced by different fish species.
Collapse
Affiliation(s)
- Kevin L Schauer
- Marine Biology and Ecology, Rosenstiel School of Marine and Atmospheric Science, University of Miami, Miami, FL, 33149, USA
| | - Christophe M R LeMoine
- Department of Biology, Brandon University, Brandon, MB, R7A 6A9, Canada.,Canadian Institute for Advanced Research, Department of Biology, University of Ottawa, Ottawa, ON, K1N 6N5, Canada
| | - Adrian Pelin
- Canadian Institute for Advanced Research, Department of Biology, University of Ottawa, Ottawa, ON, K1N 6N5, Canada
| | - Nicolas Corradi
- Canadian Institute for Advanced Research, Department of Biology, University of Ottawa, Ottawa, ON, K1N 6N5, Canada
| | - Wesley C Warren
- McDonnell Genome Institute, Washington University School of Medicine, St Louis, Missouri 63108, USA
| | - Martin Grosell
- Marine Biology and Ecology, Rosenstiel School of Marine and Atmospheric Science, University of Miami, Miami, FL, 33149, USA
| | | |
Collapse
|
22
|
Heuer RM, Munley KM, Narsinghani N, Wingar JA, Mackey T, Grosell M. Changes to Intestinal Transport Physiology and Carbonate Production at Various CO2Levels in a Marine Teleost, the Gulf Toadfish (Opsanus beta). Physiol Biochem Zool 2016; 89:402-16. [DOI: 10.1086/688235] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
|
23
|
Hu MY, Michael K, Kreiss CM, Stumpp M, Dupont S, Tseng YC, Lucassen M. Temperature Modulates the Effects of Ocean Acidification on Intestinal Ion Transport in Atlantic Cod, Gadus morhua. Front Physiol 2016; 7:198. [PMID: 27313538 PMCID: PMC4889603 DOI: 10.3389/fphys.2016.00198] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2016] [Accepted: 05/17/2016] [Indexed: 01/09/2023] Open
Abstract
CO2-driven seawater acidification has been demonstrated to enhance intestinal bicarbonate secretion rates in teleosts, leading to an increased release of CaCO3 under simulated ocean acidification scenarios. In this study, we investigated if increasing CO2 levels stimulate the intestinal acid–base regulatory machinery of Atlantic cod (Gadus morhua) and whether temperatures at the upper limit of thermal tolerance stimulate or counteract ion regulatory capacities. Juvenile G. morhua were acclimated for 4 weeks to three CO2 levels (550, 1200, and 2200 μatm) covering present and near-future natural variability, at optimum (10°C) and summer maximum temperature (18°C), respectively. Immunohistochemical analyses revealed the subcellular localization of ion transporters, including Na+/K+-ATPase (NKA), Na+/H+-exchanger 3 (NHE3), Na+/HCO3− cotransporter (NBC1), pendrin-like Cl−/HCO3− exchanger (SLC26a6), V-type H+-ATPase subunit a (VHA), and Cl− channel 3 (CLC3) in epithelial cells of the anterior intestine. At 10°C, proteins and mRNA were generally up-regulated for most transporters in the intestinal epithelium after acclimation to higher CO2 levels. This supports recent findings demonstrating increased intestinal HCO3− secretion rates in response to CO2 induced seawater acidification. At 18°C, mRNA expression and protein concentrations of most ion transporters remained unchanged or were even decreased, suggesting thermal compensation. This response may be energetically favorable to retain blood HCO3− levels to stabilize pHe, but may negatively affect intestinal salt and water resorption of marine teleosts in future oceans.
Collapse
Affiliation(s)
- Marian Y Hu
- Institute of Physiology, University of Kiel Kiel, Germany
| | - Katharina Michael
- Helmholtz Center for Polar and Marine Research, Alfred Wegener Institute Bremerhaven, Germany
| | - Cornelia M Kreiss
- Helmholtz Center for Polar and Marine Research, Alfred Wegener Institute Bremerhaven, Germany
| | - Meike Stumpp
- Helmholtz Centre for Ocean Research Kiel Kiel, Germany
| | - Sam Dupont
- Department of Biological and Environmental Sciences, The Sven Lovén Centre for Marine Sciences, University of Gothenburg Gothenburg, Sweden
| | - Yung-Che Tseng
- Department of Life Science, National Taiwan Normal University Taipei City, Taiwan
| | - Magnus Lucassen
- Helmholtz Center for Polar and Marine Research, Alfred Wegener Institute Bremerhaven, Germany
| |
Collapse
|
24
|
Robertson LM, Kochhann D, Bianchini A, Matey V, Almeida-Val VF, Val AL, Wood CM. Gill paracellular permeability and the osmorespiratory compromise during exercise in the hypoxia-tolerant Amazonian oscar (Astronotus ocellatus). J Comp Physiol B 2015; 185:741-54. [DOI: 10.1007/s00360-015-0918-4] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2015] [Revised: 06/06/2015] [Accepted: 06/10/2015] [Indexed: 01/08/2023]
|
25
|
Carvalho ESM, Gregório SF, Canário AVM, Power DM, Fuentes J. PTHrP regulates water absorption and aquaporin expression in the intestine of the marine sea bream (Sparus aurata, L.). Gen Comp Endocrinol 2015; 213:24-31. [PMID: 25562629 DOI: 10.1016/j.ygcen.2014.12.011] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/24/2013] [Revised: 12/25/2014] [Accepted: 12/27/2014] [Indexed: 11/22/2022]
Abstract
Water ingestion by drinking is fundamental for ion homeostasis in marine fish. However, the fluid ingested requires processing to allow net water absorption in the intestine. The formation of luminal carbonate aggregates impacts on calcium homeostasis and requires epithelial HCO3(-) secretion to enable water absorption. In light of its endocrine importance in calcium handling and the indication of involvement in HCO3(-) secretion the present study was designed to expose the role of the parathyroid hormone-related protein (PTHrP) in HCO3(-) secretion, water absorption and the regulation of aqp1 gene expression in the anterior intestine of the sea bream. HCO3(-) secretion rapidly decreased when PTHrP(1-34) was added to anterior intestine of the sea bream mounted in Ussing chambers. The effect achieved a maximum inhibition of 60% of basal secretion rates, showing a threshold effective dose of 0.1 ng ml(-1) compatible with reported plasma values of PTHrP. When applied in combination with the adenylate cyclase inhibitor (SQ 22.536, 100 μmol l(-1)) or the phospholipase C inhibitor (U73122, 10 μmol l(-1)) the effect of PTHrP(1-34) on HCO3(-) secretion was reduced by about 50% in both cases. In parallel, bulk water absorption measured in intestinal sacs was sensitive to inhibition by PTHrP. The inhibitory action conforms to a typical dose-response curve in the range of 0.1-1000 ng ml(-1), achieves a maximal effect of 60-65% inhibition from basal rates and shows threshold significant effects at hormone levels of 0.1 ng ml(-1). The action of PTHrP in water absorption was completely abolished in the presence of the adenylate cyclase inhibitor (SQ 22.536, 100 μmol l(-1)) and was insensitive to the phospholipase C inhibitor (U73122, 10 μmol l(-1)). In vivo injections of PTHrP(1-34) or the PTH/PTHrP receptor antagonist PTHrP(7-34) evoked respectively, a significant decrease or increase of aqp1ab, but not aqp1a. Overall the present results suggest that PTHrP acts as a key regulator of carbonate aggregate formation in the intestine of marine fish via its actions on water absorption, calcium regulation and HCO3(-) secretion.
Collapse
Affiliation(s)
- Edison S M Carvalho
- Centre of Marine Sciences (CCMar), Universidade do Algarve, Campus de Gambelas, 8005-139 Faro, Portugal
| | - Sílvia F Gregório
- Centre of Marine Sciences (CCMar), Universidade do Algarve, Campus de Gambelas, 8005-139 Faro, Portugal
| | - Adelino V M Canário
- Centre of Marine Sciences (CCMar), Universidade do Algarve, Campus de Gambelas, 8005-139 Faro, Portugal
| | - Deborah M Power
- Centre of Marine Sciences (CCMar), Universidade do Algarve, Campus de Gambelas, 8005-139 Faro, Portugal
| | - Juan Fuentes
- Centre of Marine Sciences (CCMar), Universidade do Algarve, Campus de Gambelas, 8005-139 Faro, Portugal.
| |
Collapse
|
26
|
Rubino JG, Zimmer AM, Wood CM. Intestinal ammonia transport in freshwater and seawater acclimated rainbow trout (Oncorhynchus mykiss): evidence for a Na+ coupled uptake mechanism. Comp Biochem Physiol A Mol Integr Physiol 2014; 183:45-56. [PMID: 25545914 DOI: 10.1016/j.cbpa.2014.12.037] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2014] [Revised: 12/17/2014] [Accepted: 12/19/2014] [Indexed: 12/23/2022]
Abstract
In vitro gut sac experiments were performed on freshwater and 60% seawater acclimated trout (Oncorhynchus mykiss) under treatments designed to discern possible mechanisms of intestinal ammonia transport. Seawater acclimation increased ammonia flux rate into the serosal saline (Jsamm) in the anterior intestine, however it did not alter Jsamm in the mid- or posterior intestine suggesting similar mechanisms of ammonia handling in freshwater and seawater fish. Both fluid transport rate (FTR) and Jsamm were inhibited in response to basolateral ouabain treatment, suggesting a linkage of ammonia uptake to active transport, possibly coupled to fluid transport processes via solvent drag. Furthermore, decreases in FTR and Jsamm caused by low Na(+) treatment indicated a Na(+) linked transport mechanism. Mucosal bumetanide (10(-4) M) had no impact on FTR, yet decreased Jsamm in the anterior and mid-intestine, suggesting NH4(+) substitution for K(+) on an apical NKCC, and at least a partial uncoupling of ammonia transport from fluid transport. Additional treatments (amiloride, 5-(N-ethyl-N-isopropyl)amiloride (EIPA), phenamil, bafilomycin, 4',6-diamidino-2-phenylindole (DAPI), high sodium) intended to disrupt alternative routes of Na(+) uptake yielded no change in FTR or Jsamm, suggesting the absence of direct competition between Na(+) and ammonia for transport. Finally, [(14)C]methylamine permeability (PMA) measurements indicated the likely presence of an intestinal Rh-mediated ammonia transport system, as increasing NH4Cl (0, 1, 5 mmol l(-1)) concentrations reduced PMA, suggesting competition for transport through Rh proteins. Overall, the data presented in this paper provide some of the first insights into mechanisms of teleost intestinal ammonia transport.
Collapse
Affiliation(s)
- Julian G Rubino
- McMaster University, Life Sciences Building, Department of Biology, Hamilton, Ontario L8S 4K1, Canada; Bamfield Marine Sciences Centre, Bamfield, British Columbia V0R 1B0, Canada.
| | - Alex M Zimmer
- McMaster University, Life Sciences Building, Department of Biology, Hamilton, Ontario L8S 4K1, Canada; Bamfield Marine Sciences Centre, Bamfield, British Columbia V0R 1B0, Canada
| | - Chris M Wood
- McMaster University, Life Sciences Building, Department of Biology, Hamilton, Ontario L8S 4K1, Canada; Bamfield Marine Sciences Centre, Bamfield, British Columbia V0R 1B0, Canada; Dept. of Zoology, University of British Columbia, Vancouver, British Columbia V6T 1Z4, Canada
| |
Collapse
|
27
|
Ruhr IM, Bodinier C, Mager EM, Esbaugh AJ, Williams C, Takei Y, Grosell M. Guanylin peptides regulate electrolyte and fluid transport in the Gulf toadfish (Opsanus beta) posterior intestine. Am J Physiol Regul Integr Comp Physiol 2014; 307:R1167-79. [DOI: 10.1152/ajpregu.00188.2014] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
The physiological effects of guanylin (GN) and uroguanylin (UGN) on fluid and electrolyte transport in the teleost fish intestine have yet to be thoroughly investigated. In the present study, the effects of GN, UGN, and renoguanylin (RGN; a GN and UGN homolog) on short-circuit current ( Isc) and the transport of Cl−, Na+, bicarbonate (HCO3−), and fluid in the Gulf toadfish ( Opsanus beta) intestine were determined using Ussing chambers, pH-stat titration, and intestinal sac experiments. GN, UGN, and RGN reversed the Isc of the posterior intestine (absorptive-to-secretory), but not of the anterior intestine. RGN decreased baseline HCO3− secretion, but increased Cl− and fluid secretion in the posterior intestine. The secretory response of the posterior intestine coincides with the presence of basolateral NKCC1 and apical cystic fibrosis transmembrane conductance regulator (CFTR), the latter of which is lacking in the anterior intestine and is not permeable to HCO3− in the posterior intestine. However, the response to RGN by the posterior intestine is counterintuitive given the known role of the marine teleost intestine as a salt- and water-absorbing organ. These data demonstrate that marine teleosts possess a tissue-specific secretory response, apparently associated with seawater adaptation, the exact role of which remains to be determined.
Collapse
Affiliation(s)
- Ilan M. Ruhr
- Rosenstiel School of Marine and Atmospheric Science, University of Miami, Miami, Florida; and
| | - Charlotte Bodinier
- Rosenstiel School of Marine and Atmospheric Science, University of Miami, Miami, Florida; and
| | - Edward M. Mager
- Rosenstiel School of Marine and Atmospheric Science, University of Miami, Miami, Florida; and
| | - Andrew J. Esbaugh
- Rosenstiel School of Marine and Atmospheric Science, University of Miami, Miami, Florida; and
| | - Cameron Williams
- Rosenstiel School of Marine and Atmospheric Science, University of Miami, Miami, Florida; and
| | - Yoshio Takei
- Ocean Research Institute, University of Tokyo, Tokyo, Japan
| | - Martin Grosell
- Rosenstiel School of Marine and Atmospheric Science, University of Miami, Miami, Florida; and
| |
Collapse
|
28
|
Pfister CA, Esbaugh AJ, Frieder CA, Baumann H, Bockmon EE, White MM, Carter BR, Benway HM, Blanchette CA, Carrington E, McClintock JB, McCorkle DC, McGillis WR, Mooney TA, Ziveri P. Detecting the unexpected: a research framework for ocean acidification. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2014; 48:9982-9994. [PMID: 25084232 DOI: 10.1021/es501936p] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
The threat that ocean acidification (OA) poses to marine ecosystems is now recognized and U.S. funding agencies have designated specific funding for the study of OA. We present a research framework for studying OA that describes it as a biogeochemical event that impacts individual species and ecosystems in potentially unexpected ways. We draw upon specific lessons learned about ecosystem responses from research on acid rain, carbon dioxide enrichment in terrestrial plant communities, and nitrogen deposition. We further characterize the links between carbon chemistry changes and effects on individuals and ecosystems, and enumerate key hypotheses for testing. Finally, we quantify how U.S. research funding has been distributed among these linkages, concluding that there is an urgent need for research programs designed to anticipate how the effects of OA will reverberate throughout assemblages of species.
Collapse
Affiliation(s)
- Catherine A Pfister
- Department of Ecology and Evolution, University of Chicago , Chicago, Illinois 60637, United States
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
29
|
Ando M, Wong MKS, Takei Y. Mechanisms of guanylin action on water and ion absorption at different regions of seawater eel intestine. Am J Physiol Regul Integr Comp Physiol 2014; 307:R653-63. [PMID: 24990857 DOI: 10.1152/ajpregu.00543.2013] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Guanylin (GN) inhibited water absorption and short-circuit current (Isc) in seawater eel intestine. Similar inhibition was observed after bumetanide, and the effect of bumetanide was abolished by GN or vice versa, suggesting that both act on the same target, Na(+)-K(+)-2Cl(-) cotransporter (NKCC), which is a key player for the Na(+)-K(+)-Cl(-) transport system responsible for water absorption in marine teleost intestine. However, effect of GN was always greater than that of bumetanide: 10% greater in middle intestine (MI) and 40% in posterior intestine (PI) for Isc, and 25% greater in MI and 34% in PI for water absorption. After treatment with GN, Isc decreased to zero, but 20-30% water absorption still remained. The remainder may be due to the Cl(-)/HCO3 (-) exchanger and Na(+)-Cl(-) cotransporter (NCC), since inhibitors for these transporters almost nullified the remaining water absorption. Quantitative PCR analysis revealed the presence of major proteins involved in water absorption; the NKCC2β and AQP1 genes whose expression was markedly upregulated after seawater acclimation. The SLC26A6 (anion exchanger) and NCCβ genes were also expressed in small amounts. Consistent with the inhibitors' effect, expression of NKCC2β was MI > PI, and that of NCCβ was MI << PI. The present study showed that GN not only inhibits the bumetanide-sensitive Na(+)-K(+)-Cl(-) transport system governed by NKCC2β, but also regulates unknown ion transporters different from GN-insensitive SLC26A6 and NCC. A candidate is cystic fibrosis transmembrane conductance regulator Cl(-) channel, as demonstrated in mammals, but its expression is low in eel intestine, and its role may be minor, as indicated by the small effect of its inhibitors.
Collapse
Affiliation(s)
- Masaaki Ando
- Laboratory of Physiology, Department of Marine Bioscience, Atmosphere and Ocean Research Institute, The University of Tokyo, Chiba, Japan
| | - Marty K S Wong
- Laboratory of Physiology, Department of Marine Bioscience, Atmosphere and Ocean Research Institute, The University of Tokyo, Chiba, Japan
| | - Yoshio Takei
- Laboratory of Physiology, Department of Marine Bioscience, Atmosphere and Ocean Research Institute, The University of Tokyo, Chiba, Japan
| |
Collapse
|
30
|
Esophageal desalination is mediated by Na⁺, H⁺ exchanger-2 in the gulf toadfish (Opsanus beta). Comp Biochem Physiol A Mol Integr Physiol 2014; 171:57-63. [PMID: 24548910 DOI: 10.1016/j.cbpa.2014.02.012] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2013] [Revised: 01/30/2014] [Accepted: 02/11/2014] [Indexed: 10/25/2022]
Abstract
Esophageal desalination is a crucial step in the gastrointestinal water absorption pathway, as this pre-intestinal processing establishes the osmotic conditions necessary for water absorption. Previous work has shown that esophageal Na(+) absorption is amiloride sensitive; however, it is as yet unclear if Na(+), H(+) exchangers (NHE) or Na(+) channels (ENaC) are responsible. The purpose of the current study was therefore to investigate the roles that NHE isoforms may play in this process in a marine teleost, the gulf toadfish (Opsanus beta), as well as what role NHE isoforms may play in the downstream intestinal Na(+) transport. A combination of symmetrical current clamp and asymmetrical voltage clamp experiments showed the esophagus to contain both an ion absorptive current (I(sc)=0.83±0.68) and serosal side negative transepithelial potential (TEP=-4.9±0.6). (22)Na uptake (J(Na)(m→s)) was inhibited by 0.5 mM EIPA, with no effect of 0.1 mM amiloride, 1 mM furosemide or 1 mM thiazide. A Cl(-) free saline reduced J(Na)(m→s) by 40% while also reducing conductance and reversing TEP. These results suggest that both transcellular and paracellular components contribute to esophageal Na(+) transport, with transcellular transport mediated by NHE. The NHE1, NHE2 and NHE3 genes were amplified and tissue distribution analysis by real-time PCR showed high NHE2 expression levels in the esophagus and stomach. Little NHE3 expression was observed throughout the gastrointestinal tract, and NHE2 expression was absent from the intestine. Hypersalinity (60 ppt) had no effect on the expression profile of NHE2, slc4a2, scl26a6, CAc or V-type ATPase (β-subunit), suggesting that esophageal desalination is less flexible in response to osmotic stress than the intestine.
Collapse
|
31
|
Gregório SF, Carvalho ESM, Campinho MA, Power DM, Canário AVM, Fuentes J. Endocrine regulation of carbonate precipitate formation in marine fish intestine by stanniocalcin and PTHrP. ACTA ACUST UNITED AC 2014; 217:1555-62. [PMID: 24501133 DOI: 10.1242/jeb.098517] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
In marine fish, high epithelial bicarbonate secretion by the intestine generates luminal carbonate precipitates of divalent cations that play a key role in water and ion homeostasis. In vitro studies highlight the involvement of the calciotropic hormones PTHrP (parathyroid hormone-related protein) and stanniocalcin (STC) in the regulation of epithelial bicarbonate transport. The present study tested the hypothesis that calciotropic hormones have a regulatory role in carbonate precipitate formation in vivo. Sea bream (Sparus aurata) juveniles received single intraperitoneal injections of piscine PTHrP(1-34), the PTH/PTHrP receptor antagonist PTHrP(7-34) or purified sea bream STC, or were passively immunized with polyclonal rabbit antisera raised against sea bream STC (STC-Ab). Endocrine effects on the expression of the basolateral sodium bicarbonate co-transporter (Slc4a4.A), the apical anion exchangers Slc26a6.A and Slc26a3.B, and the V-type proton pump β-subunit (Atp6v1b) in the anterior intestine were evaluated. In keeping with their calciotropic nature, the hypocalcaemic factors PTHrP(7-34) and STC up-regulated gene expression of all transporters. In contrast, the hypercalcaemic factor PTHrP(1-34) and STC antibodies down-regulated transporters involved in the bicarbonate secretion cascade. Changes in intestine luminal precipitate contents provoked by calcaemic endocrine factors validated these results: 24 h post-injection either PTHrP(1-34) or immunization with STC-Ab reduced the carbonate precipitate content in the sea bream intestine. In contrast, the PTH/PTHrP receptor antagonist PTHrP(7-34) increased not only the precipitated fraction but also the concentration of HCO3(-) equivalents in the intestinal fluid. These results confirm the hypothesis that calciotropic hormones have a regulatory role in carbonate precipitate formation in vivo in the intestine of marine fish. Furthermore, they illustrate for the first time in fish the counteracting effect of PTHrP and STC, and reveal an unexpected contribution of calcaemic factors to acid-base balance.
Collapse
Affiliation(s)
- Sílvia F Gregório
- Centre of Marine Sciences (CCMar), Campus de Gambelas, Universidade do Algarve, 8005-139 Faro, Portugal
| | | | | | | | | | | |
Collapse
|
32
|
Robertson LM, Wood CM. Measuring gill paracellular permeability with polyethelene glycol-4000 in freely swimming trout: proof of principle. J Exp Biol 2014; 217:1425-9. [DOI: 10.1242/jeb.099879] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Summary
The influence of swimming activity on gill paracellular permeability has not been measured previously in fishes. We critically assessed the use of [3H]PEG-4000 for this purpose, a substance which is also a classic marker for extracellular fluid volume, glomerular filtration rate, and drinking rate. Tests (8h) on resting freshwater trout showed that when measuring [3H]PEG-4000 clearance from the plasma in the efflux direction, correction for a large excretion via glomerular filtration was essential, necessitating urinary catheterization. When measuring [3H]PEG-4000 clearance from the water in the influx direction, correction for a significant uptake by drinking was essential, necessitating terminal gut removal, whereas glomerular filtration losses were minimal. After correction for these alternate routes of loss and uptake, [3H]PEG-4000 clearance rates by efflux from the plasma and by influx from the water were identical, showing that gill paracellular permeability is not rectified, and can be measured in either direction. The influx technique with terminal gut removal was used to assess gill paracellular permeability in trout without urinary catheters freely swimming at 1.2 body lengths per sec for 8h. Branchial [3H]PEG-4000 clearance rate (by influx from the water) increased significantly by about 80% in accord with a similar measured increase in O2 consumption rate. Thus in trout, gill paracellular permeability does increase during exercise, in accord with the traditional concept of the osmorespiratory compromise.
Collapse
|
33
|
Effects of acute temperature changes on gut physiology in two species of sculpin from the west coast of Greenland. Polar Biol 2013. [DOI: 10.1007/s00300-013-1301-0] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
|
34
|
Mekuchi M, Watanabe S, Kaneko T. Bicarbonate secreted from the pancreas contributed to the formation of Ca precipitates in Japanese eel, Anguilla japonica. ACTA ACUST UNITED AC 2012. [PMID: 23184476 DOI: 10.1002/jez.1774] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Marine teleosts produce Ca precipitates in the intestine as a product of osmoregulation. Ca precipitates are formed by a chemical reaction of Mg(2+) and Ca(2+) derived from ingested seawater with bicarbonate (HCO(3)(-)). It has been reported that HCO(3)(-) originates from the intestine; however, the pancreas is predicted to be another organ that may supply HCO(3)(-) to the intestinal tract. In the present study, the pancreas was surgically removed from Japanese eel to confirm its contribution to Ca precipitate formation. Pancreatectomized eel produced significantly less Ca precipitates than control eel in seawater, indicating that HCO(3)(-) from the pancreas contributes substantially to the formation of Ca precipitates. To further examine the molecular mechanisms of HCO(3)(-) secretion, we cloned cDNAs encoding HCO(3)(-) transporters and identified those transporters that elevated their mRNA expression in the intestine and pancreas following seawater transfer. In the intestine, mRNA expression of Slc26a6A was increased shortly after seawater transfer, whereas Slc26a1 mRNA expression increased gradually following seawater transfer. In the pancreas, Slc26a3 mRNA expression was high during the early stage of seawater acclimation, whereas Slc26a1 expression increased gradually after transfer to seawater. In the intestine and pancreas, therefore, both transient and progressively increasing types of HCO(3)(-) transporters are likely to be involved in HCO(3)(-) secretion into the intestinal lumen in a coordinated manner.
Collapse
Affiliation(s)
- Miyuki Mekuchi
- Department of Aquatic Bioscience, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Bunkyo, Tokyo, Japan.
| | | | | |
Collapse
|
35
|
Gregório SF, Carvalho ESM, Encarnação S, Wilson JM, Power DM, Canário AVM, Fuentes J. Adaptation to different salinities exposes functional specialization in the intestine of the sea bream (Sparus aurata L.). ACTA ACUST UNITED AC 2012; 216:470-9. [PMID: 23038737 DOI: 10.1242/jeb.073742] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
The processing of intestinal fluid, in addition to a high drinking rate, is essential for osmoregulation in marine fish. This study analyzed the long-term response of the sea bream (Sparus aurata L.) to relevant changes of external salinity (12, 35 and 55 p.p.t.), focusing on the anterior intestine and in the less-often studied rectum. Intestinal water absorption, epithelial HCO(3)(-) secretion and gene expression of the main molecular mechanisms (SLC26a6, SLC26a3, SLC4a4, atp6v1b, CFTR, NKCC1 and NKCC2) involved in Cl(-) and HCO(3)(-) movements were examined. The anion transporters SLC26a6 and SLC26a3 are expressed severalfold higher in the anterior intestine, while the expression of Atp6v1b (V-type H(+)-ATPase β-subunit) is severalfold higher in the rectum. Prolonged exposure to altered external salinity was without effect on water absorption but was associated with concomitant changes in intestinal fluid content, epithelial HCO(3)(-) secretion and salinity-dependent expression of SLC26a6, SLC26a3 and SLC4a4 in the anterior intestine. However, the most striking response to external salinity was obtained in the rectum, where a 4- to 5-fold increase in water absorption was paralleled by a 2- to 3-fold increase in HCO(3)(-) secretion in response to a salinity of 55 p.p.t. In addition, the rectum of high salinity-acclimated fish shows a sustained (and enhanced) secretory current (I(sc)), identified in vitro in Ussing chambers and confirmed by the higher expression of CFTR and NKCC1 and by immunohistochemical protein localization. Taken together, the present results suggest a functional anterior-posterior specialization with regard to intestinal fluid processing and subsequently to salinity adaptation of the sea bream. The rectum becomes more active at higher salinities and functions as the final controller of intestinal function in osmoregulation.
Collapse
Affiliation(s)
- Sílvia F Gregório
- Centre of Marine Sciences (CCMar), CIMAR - Laboratório Associado, Universidade do Algarve, Campus de Gambelas, 8005-139 Faro, Portugal
| | | | | | | | | | | | | |
Collapse
|
36
|
Heuer RM, Esbaugh AJ, Grosell M. Ocean Acidification Leads to Counterproductive Intestinal Base Loss in the Gulf Toadfish (Opsanus beta). Physiol Biochem Zool 2012; 85:450-9. [DOI: 10.1086/667617] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
|
37
|
Becker AG, Gonçalves JF, Burns MDM, Vieira JP, Radünz Neto J, Baldisserotto B. Ion levels in the gastrointestinal tract content of freshwater and marine-estuarine teleosts. FISH PHYSIOLOGY AND BIOCHEMISTRY 2012; 38:1001-1017. [PMID: 22160632 DOI: 10.1007/s10695-011-9585-x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/29/2011] [Accepted: 12/01/2011] [Indexed: 05/31/2023]
Abstract
This study investigated the relationship between ion levels (Na⁺, Cl⁻, K⁺, Ca²⁺, and Mg²⁺) in the fluid phase and total chyme of the contents of the gastrointestinal tract segments of freshwater and marine-estuarine teleosts collected in different salinities (0-34 ppt) in estuarine and freshwater portions of the São Gonçalo channel, southern Brazil. In addition, the relative contribution of feeding and osmoregulation to the ionic content of each portion of the gastrointestinal tract of fishes collected in different ambient salinities was analyzed. There was no relationship between salinity and ion levels in the fluid phase and total chyme of the segments of the gastrointestinal tract when considering all species together. However, there was a significant positive relationship between salinity and ion levels in the fluid phase and total chyme of two fish species (Micropogonias furnieri and Genidens barbus) collected in three or more different salinities. In most species, ion levels in the fluid phase and total chyme changed throughout the gastrointestinal tract, suggesting absorption, but the ionoregulatory mechanisms of the gastrointestinal tract seem to vary according to species.
Collapse
Affiliation(s)
- Alexssandro G Becker
- Departamento de Fisiologia e Farmacologia, Universidade Federal de Santa Maria, Santa Maria, RS, 97105-900, Brazil
- Programa de Pós-Graduação em Biodiversidade Animal, Universidade Federal de Santa Maria, Santa Maria, RS, Brazil
| | - Jamile F Gonçalves
- Departamento de Fisiologia e Farmacologia, Universidade Federal de Santa Maria, Santa Maria, RS, 97105-900, Brazil
| | - Marcelo D M Burns
- Instituto de Oceanografia, Universidade Federal do Rio Grande, Rio Grande, RS, 96201-900, Brazil
| | - João Paes Vieira
- Instituto de Oceanografia, Universidade Federal do Rio Grande, Rio Grande, RS, 96201-900, Brazil
| | - João Radünz Neto
- Departamento de Zootecnia, Universidade Federal de Santa Maria, Santa Maria, RS, 97105-900, Brazil
- Programa de Pós-Graduação em Biodiversidade Animal, Universidade Federal de Santa Maria, Santa Maria, RS, Brazil
| | - Bernardo Baldisserotto
- Departamento de Fisiologia e Farmacologia, Universidade Federal de Santa Maria, Santa Maria, RS, 97105-900, Brazil.
- Programa de Pós-Graduação em Biodiversidade Animal, Universidade Federal de Santa Maria, Santa Maria, RS, Brazil.
| |
Collapse
|
38
|
Carvalho ESM, Gregório SF, Power DM, Canário AVM, Fuentes J. Water absorption and bicarbonate secretion in the intestine of the sea bream are regulated by transmembrane and soluble adenylyl cyclase stimulation. J Comp Physiol B 2012; 182:1069-80. [PMID: 22752677 DOI: 10.1007/s00360-012-0685-4] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2012] [Revised: 06/04/2012] [Accepted: 06/09/2012] [Indexed: 10/28/2022]
Abstract
In the marine fish intestine luminal, HCO₃⁻ can remove divalent ions (calcium and magnesium) by precipitation in the form of carbonate aggregates. The process of epithelial HCO₃⁻ secretion is under endocrine control, therefore, in this study we aimed to characterize the involvement of transmembrane (tmACs) and soluble (sACs) adenylyl cyclases on the regulation of bicarbonate secretion (BCS) and water absorption in the intestine of the sea bream (Sparus aurata). We observed that all sections of sea bream intestine are able to secrete bicarbonate as measured by pH-Stat in Ussing chambers. In addition, gut sac preparations reveal net water absorption in all segments of the intestine, with significantly higher absorption rates in the anterior intestine that in the rectum. BCS and water absorption are positively correlated in all regions of the sea bream intestinal tract. Furthermore, stimulation of tmACs (10 μM FK + 500 μM IBMX) causes a significant decrease in BCS, bulk water absorption and short circuit current (Isc) in a region dependent manner. In turn, stimulation of sACs with elevated HCO₃⁻ results in a significant increase in BCS, and bulk water absorption in the anterior intestine, an action completely reversed by the sAC inhibitor KH7 (200 μM). Overall, the results reveal a functional relationship between BCS and water absorption in marine fish intestine and modulation by tmACs and sAC. In light of the present observations, it is hypothesized that the endocrine effects on intestinal BCS and water absorption mediated by tmACs are locally and reciprocally modulated by the action of sACs in the fish enterocyte, thus fine-tuning the process of carbonate aggregate production in the intestinal lumen.
Collapse
Affiliation(s)
- Edison S M Carvalho
- Centre of Marine Sciences (CCMar), CIMAR-Laboratório Associado, Universidade do Algarve, Faro, Portugal
| | | | | | | | | |
Collapse
|
39
|
Kwong RWM, Niyogi S. Cadmium transport in isolated enterocytes of freshwater rainbow trout: interactions with zinc and iron, effects of complexation with cysteine, and an ATPase-coupled efflux. Comp Biochem Physiol C Toxicol Pharmacol 2012; 155:238-46. [PMID: 21930242 DOI: 10.1016/j.cbpc.2011.09.001] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/19/2011] [Revised: 08/31/2011] [Accepted: 09/01/2011] [Indexed: 11/23/2022]
Abstract
The present study investigated the mechanisms of intestinal cadmium (Cd) uptake and efflux, using isolated enterocytes of freshwater rainbow trout (Oncorhynchus mykiss) as the experimental model. The apical uptake of free Cd(2+) in the enterocytes was a saturable and high-affinity transport process. Both zinc (Zn(2+)) and iron (Fe(2+)) inhibited cellular Cd(2+) uptake through a competitive interaction, suggesting that Cd(2+) enters enterocytes via both Zn(2+) (e.g., ZIP8) and Fe(2+) (e.g., DMT1) transport pathways. Cellular Cd(2+) uptake increased in the presence of HCO(3)(-), which resembled the function of mammalian ZIP8. Cellular Cd(2+) uptake was unaffected by Ca(2+), indicating that Cd(2+) does not compete with Ca(2+) for apical uptake. Interestingly, Cd uptake was influenced by the presence of l-cysteine, and under the exposure condition where Cd(Cys)(+) was the predominant Cd species, cellular Cd uptake rate increased with the increased concentration of Cd(Cys)(+). The kinetic analysis indicated that the uptake of Cd(Cys)(+) occurs through a low capacity transport mechanism relative to that of free Cd(2+). In addition, Cd efflux from the enterocytes decreased in the presence of an ATPase inhibitor (orthovanadate), suggesting the existence of an ATPase-coupled extrusion process. Overall, our findings provide new mechanistic insights into the intestinal Cd transport in freshwater fish.
Collapse
Affiliation(s)
- Raymond W M Kwong
- Toxicology Centre, University of Saskatchewan, Saskatoon, SK, Canada S7N 5B3
| | | |
Collapse
|
40
|
Wilson JM, Moreira-Silva JC, Delgado ILS, Ebanks SC, Vijayan MM, Coimbra J, Grosell M. Mechanisms of transepithelial ammonia excretion and luminal alkalinization in the gut of an intestinal air-breathing fish, Misgurnus anguilliacaudatus. J Exp Biol 2012; 216:623-32. [DOI: 10.1242/jeb.074401] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Summary
The weatherloach, Misgurnus angulliacaudatus, is an intestinal air-breathing, freshwater fish that has the unique ability to excrete ammonia through gut volatilization when branchial and cutaneous routes are compromised during high environmental ammonia or air exposure. We hypothesized that transepithelial gut NH4+ transport is facilitated by an apical Na+/H+ (NH4+) exchanger (NHE) and basolateral Na+/K+(NH4+)-ATPase, and that gut boundary layer alkalinization (NH4+ => NH3 + H+) is facilitated by apical HCO3- secretion through a Cl-/HCO3- anion exchanger. This was tested using a pharmacological approach with anterior (digestive) and posterior (respiratory) intestine preparations mounted in pH-stat equipped Ussing chambers. The anterior intestine had a markedly higher conductance, short circuit current and net base (Jbase) and ammonia excretions rates (Jamm) than posterior intestine. In anterior intestine, HCO3- accounted for 70% Jbase. In the presence of an imposed serosal-mucosal ammonia gradient, both NHE and Na+/K+-ATPase inhibitors EIPA (0.1mM) and ouabain (0.1mM) significantly inhibit Jamm in the anterior intestine, although only the former in the posterior intestine. In addition, the anion exchange inhibitor DIDS significantly reduced Jbase in anterior intestine although only at a high dose (1mM). Carbonic anhydrase does not appear to be associated with gut alkalization under these conditions since etoxzolamide was without effect on Jbase. Membrane fluidity of the posterior intestine was low suggesting low permeability, which was also reflected in a lower mucosal-serosal Jamm in the presence of an imposed gradient in contrast to the anterior intestine. To conclude although the posterior intestine is highly modified for gas exchange, it is the anterior intestine that is the likely site of ammonia excretion and alkalinization leading to ammonia volatilization in the gut.
Collapse
|
41
|
Brauner CJ, Gonzalez RJ, Wilson JM. Extreme Environments: Hypersaline, Alkaline, and Ion-Poor Waters. FISH PHYSIOLOGY 2012. [DOI: 10.1016/b978-0-12-396951-4.00009-8] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
|
42
|
Edwards SL, Marshall WS. Principles and Patterns of Osmoregulation and Euryhalinity in Fishes. FISH PHYSIOLOGY 2012. [DOI: 10.1016/b978-0-12-396951-4.00001-3] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/03/2022]
|
43
|
Gonzalez RJ. The physiology of hyper-salinity tolerance in teleost fish: a review. J Comp Physiol B 2011; 182:321-9. [DOI: 10.1007/s00360-011-0624-9] [Citation(s) in RCA: 60] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2011] [Revised: 09/27/2011] [Accepted: 10/04/2011] [Indexed: 10/16/2022]
|
44
|
Gilmour KM, Perry SF, Esbaugh AJ, Genz J, Taylor JR, Grosell M. Compensatory regulation of acid-base balance during salinity transfer in rainbow trout (Oncorhynchus mykiss). J Comp Physiol B 2011; 182:259-74. [PMID: 21989837 DOI: 10.1007/s00360-011-0617-8] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2011] [Revised: 09/06/2011] [Accepted: 09/19/2011] [Indexed: 11/25/2022]
Abstract
In seawater-acclimated rainbow trout (Oncorhynchus mykiss), base secretion into the intestine is a key component of the intestinal water absorption that offsets osmotic water loss to the marine environment. Acid-base balance is maintained by the matched excretion of acid equivalents via other routes, presumably the gill and/or kidney. The goal of the present study was to examine acid-base balance in rainbow trout upon transfer to more dilute environments, conditions under which base excretion into the intestine is predicted to fall, requiring compensatory adjustments of acid excretion at the gill and/or kidney if acid-base balance is to be maintained. Net acid excretion via the gill/kidney and rectal fluid, and blood acid-base status were monitored in seawater-acclimated rainbow trout maintained in seawater or transferred to iso-osmotic conditions. As predicted, transfer to iso-osmotic conditions significantly reduced base excretion into the rectal fluid (by ~48%). Transfer to iso-osmotic conditions also significantly reduced the excretion of titratable acidity via extra-intestinal routes from 183.4 ± 71.3 to -217.5 ± 42.7 μmol kg(-1) h(-1) (N = 7). At the same time, however, ammonia excretion increased significantly during iso-osmotic transfer (by ~72%) so that the apparent overall reduction in net acid excretion (from 419.7 ± 92.9 to 189.2 ± 76.5 μmol kg(-1 )h(-1); N = 7) was not significant. Trout maintained blood acid-base status during iso-osmotic transfer, although arterial pH was significantly higher in transferred fish than in those maintained in seawater. To explore the mechanisms underlying these adjustments of acid-base regulation, the relative mRNA expression and where possible, activity of a suite of proteins involved in acid-base balance were examined in intestine, gill and kidney. At the kidney, reduced mRNA expression of carbonic anhydrase (CA; cytosolic and membrane-associated CA IV), V-type H(+)-ATPase, and Na(+)/HCO(3) (-) co-transporter were consistent with a reduced role in net acid excretion following iso-osmotic transfer. Changes in relative mRNA expression and/or activity at the intestine and gill were consistent with the roles of these organs in osmotic rather than acid-base regulation. Overall, the data emphasize the coordination of acid-base, osmoregulatory and ionoregulatory processes that occur with salinity transfer in a euryhaline fish.
Collapse
Affiliation(s)
- K M Gilmour
- Department of Biology, University of Ottawa, 30 Marie Curie, Ottawa, ON, K1N 6N5, Canada.
| | | | | | | | | | | |
Collapse
|
45
|
Guffey S, Esbaugh A, Grosell M. Regulation of apical H⁺-ATPase activity and intestinal HCO₃⁻ secretion in marine fish osmoregulation. Am J Physiol Regul Integr Comp Physiol 2011; 301:R1682-91. [PMID: 21865541 DOI: 10.1152/ajpregu.00059.2011] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
The absorption of Cl(-) and water from ingested seawater in the marine fish intestine is accomplished partly through Cl(-)/HCO(3)(-) exchange. Recently, a H(+) pump (vacuolar-type H(+)-ATPase) was found to secrete acid into the intestinal lumen, and it may serve to titrate luminal HCO(3)(-) and facilitate further Cl(-)/HCO(3)(-) exchange, especially in the posterior intestine, where adverse concentration gradients could limit Cl(-)/HCO(3)(-) exchange. The H(+) pump is expressed in all intestinal segments and in gill tissue of gulf toadfish (Opsanus beta) maintained in natural seawater. After acute transfer of toadfish to 60 ppt salinity, H(+) pump expression increased 20-fold in the posterior intestine. In agreement with these observations was a fourfold-increased H(+)-ATPase activity in the posterior intestine of animals acclimated to 60 ppt salinity. Interestingly, Na(+)-K(+)-ATPase activity was elevated in the anterior intestine and gill, but not in the posterior intestine. Apical acid secretion by isolated intestinal tissue mounted in Ussing chambers fitted with pH-stat titration systems increased after acclimation to hypersalinity in the anterior and posterior intestine, titrating >20% of secreted bicarbonate. In addition, net base secretion increased in hypersalinity-acclimated fish and was ∼70% dependent on serosal HCO(3)(-). Protein localization by immunohistochemistry confirmed the presence of the vacuolar-type H(+)-ATPase in the apical region of intestinal enterocytes. These results show that the H(+) pump, especially in the posterior intestine, plays an important role in hypersaline osmoregulation and that it likely has significant effects on HCO(3)(-) accumulation in the intestinal lumen and, therefore, the continued absorption of Cl(-) and water.
Collapse
Affiliation(s)
- S Guffey
- Rosenstiel School of Marine and Atmospheric Sciences, University of Miami, Miami, Florida 33149, USA.
| | | | | |
Collapse
|
46
|
Osmoregulation and epithelial water transport: lessons from the intestine of marine teleost fish. J Comp Physiol B 2011; 182:1-39. [DOI: 10.1007/s00360-011-0601-3] [Citation(s) in RCA: 97] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2011] [Revised: 06/08/2011] [Accepted: 06/15/2011] [Indexed: 12/15/2022]
|
47
|
Grosell M. Intestinal anion exchange in marine teleosts is involved in osmoregulation and contributes to the oceanic inorganic carbon cycle. Acta Physiol (Oxf) 2011; 202:421-34. [PMID: 21362153 DOI: 10.1111/j.1748-1716.2010.02241.x] [Citation(s) in RCA: 74] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Marine teleost fish osmoregulation involves seawater ingestion and intestinal fluid absorption. Solute coupled fluid absorption by the marine teleost fish intestine has long been believed to be the product of Na(+) and Cl(-) absorption via the Na(+) :K(+) :2Cl(-) co-transporter (NKCC2). However, the past decade has revealed that intestinal anion exchange contributes significantly to Cl(-) absorption, in exchange for HCO(3) (-) secretion, and that this process is important for intestinal water absorption. In addition to contributing to solute coupled water absorption intestinal anion exchange results in luminal precipitation of CaCO(3) which acts to reduce luminal osmotic pressure and thus assist water absorption. Most recently, activity of apical H(+) -pumps, especially in distal segments of the intestine have been suggested to not only promote anion exchange, but also to reduce luminal osmotic pressure by preventing excess HCO(3)(-) concentrations from accumulating in intestinal fluids, thereby aiding water absorption. The present review summarizes and synthesizes the most recent advances in our view of marine teleosts osmoregulation, including our emerging understanding of epithelial transport of acid-base equivalents in the intestine, the consequences for whole organism acid-base balance and finally the impact of piscine CaCO(3) formation on the global oceanic carbon cycle.
Collapse
Affiliation(s)
- M Grosell
- RSMAS, University of Miami, Miami, FL 33149-1098, USA.
| |
Collapse
|
48
|
Intestinal transport following transfer to increased salinity in an anadromous fish (Oncorhynchus mykiss). Comp Biochem Physiol A Mol Integr Physiol 2011; 159:150-8. [DOI: 10.1016/j.cbpa.2011.02.011] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2010] [Revised: 02/12/2011] [Accepted: 02/14/2011] [Indexed: 11/23/2022]
|
49
|
Fish as major carbonate mud producers and missing components of the tropical carbonate factory. Proc Natl Acad Sci U S A 2011; 108:3865-9. [PMID: 21368155 DOI: 10.1073/pnas.1015895108] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Carbonate mud is a major constituent of recent marine carbonate sediments and of ancient limestones, which contain unique records of changes in ocean chemistry and climate shifts in the geological past. However, the origin of carbonate mud is controversial and often problematic to resolve. Here we show that tropical marine fish produce and excrete various forms of precipitated (nonskeletal) calcium carbonate from their guts ("low" and "high" Mg-calcite and aragonite), but that very fine-grained (mostly < 2 μm) high Mg-calcite crystallites (i.e., > 4 mole % MgCO(3)) are their dominant excretory product. Crystallites from fish are morphologically diverse and species-specific, but all are unique relative to previously known biogenic and abiotic sources of carbonate within open marine systems. Using site specific fish biomass and carbonate excretion rate data we estimate that fish produce ∼6.1 × 10(6) kg CaCO(3)/year across the Bahamian archipelago, all as mud-grade (the < 63 μm fraction) carbonate and thus as a potential sediment constituent. Estimated contributions from fish to total carbonate mud production average ∼14% overall, and exceed 70% in specific habitats. Critically, we also document the widespread presence of these distinctive fish-derived carbonates in the finest sediment fractions from all habitat types in the Bahamas, demonstrating that these carbonates have direct relevance to contemporary carbonate sediment budgets. Fish thus represent a hitherto unrecognized but significant source of fine-grained carbonate sediment, the discovery of which has direct application to the conceptual ideas of how marine carbonate factories function both today and in the past.
Collapse
|
50
|
Assimilation of water and dietary ions by the gastrointestinal tract during digestion in seawater-acclimated rainbow trout. J Comp Physiol B 2011; 181:615-30. [DOI: 10.1007/s00360-011-0550-x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2010] [Revised: 12/31/2010] [Accepted: 01/02/2011] [Indexed: 10/18/2022]
|