1
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Nelson C, Dichiera AM, Brauner CJ. Developing rainbow trout (Oncorhynchus mykiss) lose branchial plasma accessible carbonic anhydrase expression with hatch and the transition to pH-sensitive, adult hemoglobin polymorphs. J Comp Physiol B 2024; 194:537-543. [PMID: 38698121 DOI: 10.1007/s00360-024-01557-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2023] [Revised: 03/03/2024] [Accepted: 04/15/2024] [Indexed: 05/05/2024]
Abstract
Salmonids possess a unique respiratory system comprised of three major components: highly pH-sensitive hemoglobins, red blood cell (RBC) intracellular pH (pHi) protection, and a heterogeneous distribution of plasma accessible carbonic anhydrase (paCA), specifically with absence of paCA at the gills. These characteristics are thought to have evolved to enhance oxygen unloading to the tissues while protecting uptake at the gills. Our knowledge of this system is detailed in adults, but little is known about it through development. Developing rainbow trout (Oncorhynchus mykiss) express embryonic RBCs containing hemoglobins that are relatively insensitive to pH; however, availability of gill paCA and RBC pHi protection is unknown. We show that pre-hatch rainbow trout express gill paCA, which is lost in correlation with the emergence of highly pH-sensitive adult hemoglobins and RBC pHi protection. Rainbow trout therefore exhibit a switch in respiratory strategy with hatch. We conclude that gill paCA likely represents an embryonic trait in rainbow trout and is constrained in adults due to their highly pH-sensitive hemoglobins.
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Affiliation(s)
| | | | - Colin J Brauner
- University of British Columbia, Vancouver, BC, V6T 1Z4, Canada
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2
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Shartau RB, Harter TS, Baker DW, Aboagye DL, Allen PJ, Val AL, Crossley DA, Kohl ZF, Hedrick MS, Damsgaard C, Brauner CJ. Acute CO 2 tolerance in fishes is associated with air breathing but not the Root effect, red cell βNHE, or habitat. Comp Biochem Physiol A Mol Integr Physiol 2022; 274:111304. [PMID: 36049728 DOI: 10.1016/j.cbpa.2022.111304] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2021] [Revised: 08/03/2022] [Accepted: 08/07/2022] [Indexed: 12/01/2022]
Abstract
High CO2 (hypercapnia) can impose significant physiological challenges associated with acid-base regulation in fishes, impairing whole animal performance and survival. Unlike other environmental conditions such as temperature and O2, the acute CO2 tolerance thresholds of fishes are not understood. While some fish species are highly tolerant, the extent of acute CO2 tolerance and the associated physiological and ecological traits remain largely unknown. To investigate this, we used a recently developed ramping assay, termed the Carbon Dioxide maximum (CDmax), that increases CO2 exposure until loss of equilibrium (LOE) is observed. We investigated if there was a relationship between CO2 tolerance and the Root effect, β-adrenergic sodium proton exchanger (βNHE), air-breathing, and fish habitat in 17 species. We hypothesized that CO2 tolerance would be higher in fishes that lack both a Root effect and βNHE, breathe air, and reside in tropical habitats. Our results showed that CDmax ranged from 2.7 to 26.7 kPa, while LOE was never reached in four species at the maximum PCO2 we could measure (26.7 kPa); CO2 tolerance was only associated with air-breathing, but not the presence of a Root effect or a red blood cell (RBC) βNHE, or fish habitat. This study demonstrates that the diverse group of fishes investigated here are incredibly tolerant of CO2 and that although this tolerance is associated with air-breathing, further investigations are required to understand the basis for CO2 tolerance.
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Affiliation(s)
- R B Shartau
- Department of Biology, The University of Texas at Tyler, Tyler, TX, USA; Department of Zoology, University of British Columbia, Vancouver, BC, Canada.
| | - T S Harter
- Department of Zoology, University of British Columbia, Vancouver, BC, Canada; Marine Biology Research Division, Scripps Institution of Oceanography, University of California, San Diego, CA, USA.
| | - D W Baker
- Department of Fisheries and Aquaculture, Vancouver Island University, Nanaimo, BC, Canada.
| | - D L Aboagye
- Department of Wildlife, Fisheries and Aquaculture, Mississippi State University, Starkville, MS, USA
| | - P J Allen
- Department of Wildlife, Fisheries and Aquaculture, Mississippi State University, Starkville, MS, USA.
| | - A L Val
- Laboratory of Ecophysiology and Molecular Evolution, Brazilian National Institute for Research of the Amazon (INPA), Manaus, AM, Brazil
| | - D A Crossley
- Department of Biological Sciences, University of North Texas, Denton, TX, USA.
| | - Z F Kohl
- Department of Biological Sciences, University of North Texas, Denton, TX, USA
| | - M S Hedrick
- Department of Biological Sciences, California State University, East Bay, Hayward, CA, USA.
| | - C Damsgaard
- Section for Zoophysiology, Department of Biology, Aarhus University, Aarhus, Denmark.
| | - C J Brauner
- Department of Zoology, University of British Columbia, Vancouver, BC, Canada.
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3
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Pelster B, Wood CM, Braz-Mota S, Val AL. Gills and air-breathing organ in O 2 uptake, CO 2 excretion, N-waste excretion, and ionoregulation in small and large pirarucu (Arapaima gigas). J Comp Physiol B 2020; 190:569-583. [PMID: 32529591 DOI: 10.1007/s00360-020-01286-1] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2020] [Revised: 05/15/2020] [Accepted: 05/29/2020] [Indexed: 01/11/2023]
Abstract
In the pirarucu (Arapaima gigas), gill surface area and thus gas exchange capacity of the gills are reduced with proceeding development. It, therefore, is expected that A. gigas, starting as a water breather, progressively turns into an obligate air-breathing fish using an air-breathing organ (ABO) for gas exchange. We assessed the air-breathing activity, O2 and CO2 exchange into air and water, ammonia-N and urea-N excretion, ion flux rates, and activities of ion transport ATPases in large versus small pirarucu. We found that even very young A. gigas (4-6 g, 2-3 weeks post-hatch) with extensive gills are air-breathers (18.1 breaths*h-1) and cover most (63%) of their O2 requirements from the air whereas 600-700-g animals (about 3-4 months post-hatch), with reduced gills, obtain 75% of their O2 from the air (10.8 breaths*h-1). Accordingly, the reduction in gill surface area hardly affected O2 uptake, but development had a significant effect on aerial CO2 excretion, which was very low (3%) in small fish and increased to 12% in larger fish, yielding a hyper-allometric scaling coefficient (1.12) in contrast to 0.82-0.84 for aquatic and total CO2 excretion. Mass-specific ammonia excretion decreased in approximate proportion to mass-specific O2 consumption as the fish grew, but urea-N excretion dropped from 18% (at 4-6 g) to 8% (at 600-700 g) of total N-excretion; scaling coefficients for all these parameters were 0.70-0.80. Mass-specific sodium influx and efflux rates, as well as potassium net loss rates, departed from this pattern, being greater in larger fish; hyper-allometric scaling coefficients were > 1.0. Gill V-type H+ ATPase activities were greater than Na+, K+-ATPase activities, but levels were generally low and comparable in large and small fish, and similar activities were detected in the ABO. A. gigas is a carnivorous fish throughout its lifecycle, and, despite fasting, protein oxidation accounted for the major portion (61-82%) of aerobic metabolism in both large and small animals. ABO PO2 and PCO2 (measured in 600-700-g fish) were quite variable, and aerial hypoxia resulted in lower ABO PO2 values. Under normoxic conditions, a positive correlation between breath volume and ABP PO2 was detected, and on average with a single breath more than 50% of the ABO volume was exchanged. ABO PCO2 values were in the range of 1.95-3.89 kPa, close to previously recorded blood PCO2 levels. Aerial hypoxia (PO2 down to 12.65 kPa) did not increase either air-breathing frequency or breath volume.
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Affiliation(s)
- Bernd Pelster
- Institute of Zoology, University of Innsbruck, Innsbruck, Austria
- Center for Molecular Biosciences, University of Innsbruck, Innsbruck, Austria
| | - Chris M Wood
- Department of Zoology, University of British Columbia, Vancouver, BC, V6T 1Z4, Canada.
- Department of Biology, McMaster University, Hamilton, ON, L8S 4K1, Canada.
| | - Susana Braz-Mota
- Laboratory of Ecophysiology and Molecular Evolution, Brazilian National Institute for Research of the Amazon, Manaus, Brazil
| | - Adalberto L Val
- Laboratory of Ecophysiology and Molecular Evolution, Brazilian National Institute for Research of the Amazon, Manaus, Brazil
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4
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The NOS/NO system in an example of extreme adaptation: The African lungfish. J Therm Biol 2020; 90:102594. [PMID: 32479389 DOI: 10.1016/j.jtherbio.2020.102594] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2019] [Revised: 03/21/2020] [Accepted: 04/07/2020] [Indexed: 12/30/2022]
Abstract
African dipnoi (lungfish) are aestivating fish and obligate air breathers that, throughout their complex life cycle, undergo remarkable morpho-functional organ readjustment from biochemical to morphological level. In the present review we summarize the changes of the NOS/NO (Nitric Oxide Synthase/Nitric Oxide) system occurring in lungs, gills, kidney, heart, and myotomal muscle of African lungfish of the genus Protopterus (P. dolloi and P. annectens), in relation to the switch from freshwater to aestivation, and vice-versa. In particular, the expression and localization patterns of NOS, and its protein partners Akt, Hsp-90 and HIF-1α, have been discussed, together with the apoptosis rate, evaluated by TUNEL technique. We hypothesize that all these molecular components are crucial in signalling transduction/integration networks induced by environmental challenges (temperature, dehydration, inactivity)experienced at the beginning, during, and at the end of the dry season.
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5
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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.
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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
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6
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Shartau RB, Damsgaard C, Brauner CJ. Limits and patterns of acid-base regulation during elevated environmental CO2 in fish. Comp Biochem Physiol A Mol Integr Physiol 2019; 236:110524. [DOI: 10.1016/j.cbpa.2019.110524] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2019] [Revised: 05/29/2019] [Accepted: 07/07/2019] [Indexed: 01/07/2023]
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7
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Tuong DD, Huong DTT, Phuong NT, Bayley M, Milsom WK. Ventilatory responses of the clown knifefish, Chitala ornata, to arterial hypercapnia remain after gill denervation. J Comp Physiol B 2019; 189:673-683. [PMID: 31552490 DOI: 10.1007/s00360-019-01236-6] [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: 03/07/2019] [Revised: 08/22/2019] [Accepted: 09/12/2019] [Indexed: 01/20/2023]
Abstract
The aim of this study was to corroborate the presence of CO2/H+-sensitive arterial chemoreceptors involved in producing air-breathing responses to aquatic hypercarbia in the facultative air-breathing clown knifefish (Chitala ornata) and to explore their possible location. Progressively increasing levels of CO2 mixed with air were injected into the air-breathing organ (ABO) of one group of intact fish to elevate internal PCO2 and decrease blood pH. Another group of fish in which the gills were totally denervated was exposed to aquatic hypercarbia (pH ~ 6) or arterial hypercapnia in aquatic normocarbia (by injection of acetazolamide to increase arterial PCO2 and decrease blood pH). Air-breathing frequency, gill ventilation frequency, heart rate and arterial PCO2 and pH were recorded during all treatments. The CO2 injections into the ABO induced progressive increases in air-breathing frequency, but did not alter gill ventilation or heart rate. Exposure to both hypercarbia and acetazolamide post-denervation of the gills also produced significant air-breathing responses, but no changes in gill ventilation. While all treatments produced increases in arterial PCO2 and decreases in blood pH, the modest changes in arterial PCO2/pH in the acetazolamide treatment produced the greatest increases in air-breathing frequency. These results strengthen the evidence that internal CO2/H+ sensing is involved in the stimulation of air breathing in clown knifefish and suggest that it involves extra-branchial chemoreceptors possibly situated either centrally or in the air-breathing organ.
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Affiliation(s)
- Dang Diem Tuong
- College of Aquaculture and Fisheries, Can Tho University, Can Tho, Vietnam.
| | - Do Thi Thanh Huong
- College of Aquaculture and Fisheries, Can Tho University, Can Tho, Vietnam
| | | | - Mark Bayley
- Department of Bioscience Zoophysiology, Aarhus University, Aarhus, Denmark
| | - William K Milsom
- Department of Zoology, University of British Columbia, Vancouver, Canada
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8
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Bayley M, Damsgaard C, Thomsen M, Malte H, Wang T. Learning to Air-Breathe: The First Steps. Physiology (Bethesda) 2019; 34:14-29. [DOI: 10.1152/physiol.00028.2018] [Citation(s) in RCA: 33] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
Air-breathing in vertebrates has evolved many times among the bony fish while in water. Its appearance has had a fundamental impact on the regulation of ventilation and acid-base status. We review the physico-chemical constraints imposed by water and air, place the extant air-breathing fish into this framework, and show how that the advantages of combining control of ventilation and acid-base status are only available to the most obligate of air-breathing fish, thus highlighting promising avenues for research.
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Affiliation(s)
- Mark Bayley
- Section for Zoophysiology, Department of Bioscience, Aarhus University, Aarhus, Denmark
| | - Christian Damsgaard
- Department of Zoology, University of British Columbia, Vancouver, British Columbia, Canada
| | - Mikkel Thomsen
- Section for Zoophysiology, Department of Bioscience, Aarhus University, Aarhus, Denmark
| | - Hans Malte
- Section for Zoophysiology, Department of Bioscience, Aarhus University, Aarhus, Denmark
| | - Tobias Wang
- Section for Zoophysiology, Department of Bioscience, Aarhus University, Aarhus, Denmark
- Aarhus Institute of Advanced Sciences, Aarhus University, Aarhus, Denmark
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9
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Florindo LH, Armelin VA, McKenzie DJ, Rantin FT. Control of air-breathing in fishes: Central and peripheral receptors. Acta Histochem 2018; 120:642-653. [PMID: 30219242 DOI: 10.1016/j.acthis.2018.08.010] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
This review considers the environmental and systemic factors that can stimulate air-breathing responses in fishes with bimodal respiration, and how these may be controlled by peripheral and central chemoreceptors. The systemic factors that stimulate air-breathing in fishes are usually related to conditions that increase the O2 demand of these animals (e.g. physical exercise, digestion and increased temperature), while the environmental factors are usually related to conditions that impair their capacity to meet this demand (e.g. aquatic/aerial hypoxia, aquatic/aerial hypercarbia, reduced aquatic hidrogenionic potential and environmental pollution). It is now well-established that peripheral chemoreceptors, innervated by cranial nerves, drive increased air-breathing in response to environmental hypoxia and/or hypercarbia. These receptors are, in general, sensitive to O2 and/or CO2/H+ levels in the blood and/or the environment. Increased air-breathing in response to elevated O2 demand may also be driven by the peripheral chemoreceptors that monitor O2 levels in the blood. Very little is known about central chemoreception in air-breathing fishes, the data suggest that central chemosensitivity to CO2/H+ is more prominent in sarcopterygians than in actinopterygians. A great deal remains to be understood about control of air-breathing in fishes, in particular to what extent control systems may show commonalities (or not) among species or groups that have evolved air-breathing independently, and how information from the multiple peripheral (and possibly central) chemoreceptors is integrated to control the balance of aerial and aquatic respiration in these animals.
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Affiliation(s)
- Luiz Henrique Florindo
- Department of Zoology and Botany, São Paulo State University (UNESP), Rua Cristóvão Colombo, 2265, São José do Rio Preto, SP, 15054-000, Brazil; Aquaculture Center (CAUNESP), São Paulo State University (UNESP), Rodovia Prof. Paulo Donato Castellane, n/n, Jaboticabal, SP, 14884-900, Brazil
| | - Vinicius Araújo Armelin
- Department of Zoology and Botany, São Paulo State University (UNESP), Rua Cristóvão Colombo, 2265, São José do Rio Preto, SP, 15054-000, Brazil
| | - David John McKenzie
- Centre for Marine Biodiversity Exploitation and Conservation, UMR9190 (IRD, Ifremer, UM, CNRS), Université Montpellier, Place Eugène Bataillon cc 093, 34095 Montpellier Cedex 5, France; Department of Physiological Sciences, Federal University of São Carlos (UFSCar), Rodovia Washington Luiz, km 235, São Carlos, SP, 13565-905, Brazil
| | - Francisco Tadeu Rantin
- Department of Physiological Sciences, Federal University of São Carlos (UFSCar), Rodovia Washington Luiz, km 235, São Carlos, SP, 13565-905, Brazil.
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Rousselet E, Stacy NI, Rotstein DS, Waltzek TB, Griffin MJ, Francis-Floyd R. Systemic Edwardsiella tarda infection in a Western African lungfish (Protopterus annectens) with cytologic observation of heterophil projections. JOURNAL OF FISH DISEASES 2018; 41:1453-1458. [PMID: 29882594 DOI: 10.1111/jfd.12831] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/05/2018] [Revised: 04/24/2018] [Accepted: 04/26/2018] [Indexed: 06/08/2023]
Abstract
This report describes a case of systemic bacterial infection caused by Edwardsiella tarda in a Western African lungfish (Protopterus annectens) exposed to poor environmental and husbandry conditions. The fish presented with a large, external ulcerative lesion and died 2 weeks after developing anorexia. Histological evaluation revealed multifocal areas of necrosis and heterophilic and histiocytic inflammation throughout multiple tissues. Gram stain identified small numbers of intra- and extracellular monomorphic Gram-negative 1 to 2 μm rod-shaped bacilli. Cytology of lung granuloma, kidney and testes imprints identified heterophilic inflammation with phagocytosis of small monomorphic bacilli and some heterophils exhibiting cytoplasmic projections indicative of heterophil extracellular traps (HETs). Initial phenotypic analysis of isolates from coelomic fluid cultures identified E. tarda. Subsequent molecular analysis of spleen, liver and intestine DNA using an E. tarda-specific endpoint PCR assay targeting the bacterial fimbrial subunit yielded a 115 bp band. Sequencing and BLASTN search revealed the sequence was identical (76/76) to E. tarda strain FL95-01 (GenBank acc. CP011359) and displayed 93% sequence identity (66/71) to Edwardsiella hoshinae strain ATCC 35051 (GenBank acc. CP011359). This is the first report of systemic edwardsiellosis in a lungfish with concurrent cytologically identified structures suggestive of HETs.
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Affiliation(s)
- Estelle Rousselet
- Aquatic Animal Health Program, Department of Large Animal Clinical Sciences, College of Veterinary Medicine, University of Florida, Gainesville, Florida
| | - Nicole I Stacy
- Comparative, Diagnostic and Population Medicine, University of Florida, Gainesville, Florida
| | | | - Tom B Waltzek
- Department of Infectious Diseases and Immunology, University of Florida, Gainesville, Florida
| | - Matt J Griffin
- Department of Pathobiology and Population Medicine, College of Veterinary Medicine, Mississippi State University, Stoneville, Mississippi
| | - Ruth Francis-Floyd
- College of Veterinary Medicine and School of Forest Resources and Conservation, University of Florida, Gainesville, Florida
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11
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Harter TS, Brauner CJ. The O 2 and CO 2 Transport System in Teleosts and the Specialized Mechanisms That Enhance Hb–O 2 Unloading to Tissues. ACTA ACUST UNITED AC 2017. [DOI: 10.1016/bs.fp.2017.09.001] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
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12
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Zena LA, Bícego KC, da Silva GSF, Giusti H, Glass ML, Sanchez AP. Acute effects of temperature and hypercarbia on cutaneous and branchial gas exchange in the South American lungfish, Lepidosiren paradoxa. J Therm Biol 2016; 63:112-118. [PMID: 28010808 DOI: 10.1016/j.jtherbio.2016.12.001] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2016] [Revised: 11/21/2016] [Accepted: 12/01/2016] [Indexed: 11/25/2022]
Abstract
The South American lungfish, Lepidosiren paradoxa inhabits seasonal environments in the Central Amazon and Paraná-Paraguay basins that undergo significant oscillations in temperature throughout the year. They rely on different gas exchange organs, such as gills and skin for aquatic gas exchange while their truly bilateral lungs are responsible for aerial gas exchange; however, there are no data available on the individual contributions of the skin and the gills to total aquatic gas exchange in L. paradoxa. Thus, in the present study we quantify the relative contributions of skin and gills on total aquatic gas exchange during warm (35°C) and cold exposure (20°C) in addition to the effects of aerial and aquatic hypercarbia on aquatic gas exchange and gill ventilation rate (fG; 25°C), respectively. Elevated temperature (35°C) caused a significant increase in the contribution of cutaneous (from 0.61±0.13 to 1.34±0.26ml. STPD.h-1kg-1) and branchial (from 0.54±0.17 to 1.73±0.53ml. STPD.h-1kg-1) gas exchange for V̇CO2 relative to the lower temperature (20°C), while V̇O2 remained relatively unchanged. L. paradoxa exhibited a greater branchial contribution in relation to total aquatic gas exchange at lower temperatures (20 and 25°C) for oxygen uptake. Aerial hypercarbia decreased branchial V̇O2 whereas branchial V̇CO2 was significantly increased. Progressive increases in aquatic hypercarbia did not affect fG. This response is in contrast to increases in pulmonary ventilation that may offset any increase in arterial partial pressure of CO2 owing to CO2 loading through the animals' branchial surface. Thus, despite their reduced contribution to total gas exchange, cutaneous and branchial gas exchange in L. paradoxa can be significantly affected by temperature and aerial hypercarbia.
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Affiliation(s)
- Lucas A Zena
- Department of Animal Morphology and Physiology, College of Agricultural and Veterinary Sciences, São Paulo State University, Jaboticabal, SP 14884-900, Brazil; National Institute of Science and Technology in Comparative Physiology (INCT Fisiologia Comparada), Brazil.
| | - Kênia C Bícego
- Department of Animal Morphology and Physiology, College of Agricultural and Veterinary Sciences, São Paulo State University, Jaboticabal, SP 14884-900, Brazil; National Institute of Science and Technology in Comparative Physiology (INCT Fisiologia Comparada), Brazil
| | - Glauber S F da Silva
- Department of Animal Morphology and Physiology, College of Agricultural and Veterinary Sciences, São Paulo State University, Jaboticabal, SP 14884-900, Brazil; National Institute of Science and Technology in Comparative Physiology (INCT Fisiologia Comparada), Brazil
| | - Humberto Giusti
- Department of Physiology, Faculty of Medicine of Ribeirão Preto, University of São Paulo, Ribeirão Preto, SP, Brazil
| | - Mogens L Glass
- Department of Physiology, Faculty of Medicine of Ribeirão Preto, University of São Paulo, Ribeirão Preto, SP, Brazil
| | - Adriana P Sanchez
- Faculty of Health Sciences of Barretos Dr. Paulo Prata (FACISB), Barretos, SP, Brazil
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13
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Chng YR, Ong JLY, Ching B, Chen XL, Hiong KC, Wong WP, Chew SF, Lam SH, Ip YK. Molecular Characterization of Aquaporin 1 and Aquaporin 3 from the Gills of the African Lungfish, Protopterus annectens, and Changes in Their Branchial mRNA Expression Levels and Protein Abundance during Three Phases of Aestivation. Front Physiol 2016; 7:532. [PMID: 27891097 PMCID: PMC5102888 DOI: 10.3389/fphys.2016.00532] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2016] [Accepted: 10/25/2016] [Indexed: 01/07/2023] Open
Abstract
African lungfishes can undergo long periods of aestivation on land during drought. During aestivation, lungfishes are confronted with desiccation and dehydration, and their gills become non-functional and covered with a thick layer of dried mucus. Aquaporins (Aqps) are a superfamily of integral membrane proteins which generally facilitate the permeation of water through plasma membranes. This study aimed to obtain the complete cDNA coding sequences of aqp1 and aqp3 from the gills of Protopterus annectens, and to determine their branchial mRNA and protein expression levels during the induction, maintenance and arousal phases of aestivation. Dendrogramic analyses of the deduced Aqp1 and Aqp3 amino acid sequences of P. annectens revealed their close relationships with those of Latimeria chalumnae and tetrapods. During the induction phase, there were significant decreases in the transcript levels of aqp1 and aqp3 in the gills of P. annectens, but the branchial Aqp1 and Aqp3 protein abundance remained unchanged. As changes in transcription might precede changes in translation, this could be regarded as an adaptive response to decrease the protein abundance of Aqp1 and Aqp3 in the subsequent maintenance phase of aestivation. As expected, the branchial transcript levels and protein abundance of aqp1/Aqp1 and aqp3/Aqp3 were significantly down-regulated during the maintenance phase, probably attributable to the shutdown of branchial functions and the cessation of volume regulation of branchial epithelial cells. Additionally, these changes could reduce the loss of water through branchial epithelial surfaces, supplementing the anti-desiccating property of the dried mucus. Upon arousal, it was essential for the lungfish to restore branchial functions. Indeed, the protein abundance of Aqp1 recovered partially, with complete recovery of mRNA expression level and protein abundance of Aqp3, in the gills of P. annectens after 3 days of arousal. These results provide insights into how P. annectens regulates branchial Aqp expression to cope with desiccation and rehydration during different phases of aestivation.
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Affiliation(s)
- You R. Chng
- Department of Biological Sciences, National University of SingaporeSingapore, Singapore
| | - Jasmine L. Y. Ong
- Department of Biological Sciences, National University of SingaporeSingapore, Singapore
| | - Biyun Ching
- Department of Biological Sciences, National University of SingaporeSingapore, Singapore
| | - Xiu L. Chen
- Department of Biological Sciences, National University of SingaporeSingapore, Singapore
| | - Kum C. Hiong
- Department of Biological Sciences, National University of SingaporeSingapore, Singapore
| | - Wai P. Wong
- Department of Biological Sciences, National University of SingaporeSingapore, Singapore
| | - Shit F. Chew
- Natural Sciences and Science Education, National Institute of Education, Nanyang Technological UniversitySingapore, Singapore
| | - Siew H. Lam
- Department of Biological Sciences, National University of SingaporeSingapore, Singapore
- NUS Environmental Research Institute, National University of SingaporeSingapore, Singapore
| | - Yuen K. Ip
- Department of Biological Sciences, National University of SingaporeSingapore, Singapore
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14
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Lefevre S, Bayley M, McKenzie DJ. Measuring oxygen uptake in fishes with bimodal respiration. JOURNAL OF FISH BIOLOGY 2016; 88:206-231. [PMID: 26358224 DOI: 10.1111/jfb.12698] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/12/2014] [Accepted: 03/17/2015] [Indexed: 06/05/2023]
Abstract
Respirometry is a robust method for measurement of oxygen uptake as a proxy for metabolic rate in fishes, and how species with bimodal respiration might meet their demands from water v. air has interested researchers for over a century. The challenges of measuring oxygen uptake from both water and air, preferably simultaneously, have been addressed in a variety of ways, which are briefly reviewed. These methods are not well-suited for the long-term measurements necessary to be certain of obtaining undisturbed patterns of respiratory partitioning, for example, to estimate traits such as standard metabolic rate. Such measurements require automated intermittent-closed respirometry that, for bimodal fishes, has only recently been developed. This paper describes two approaches in enough detail to be replicated by the interested researcher. These methods are for static respirometry. Measuring oxygen uptake by bimodal fishes during exercise poses specific challenges, which are described to aid the reader in designing experiments. The respiratory physiology and behaviour of air-breathing fishes is very complex and can easily be influenced by experimental conditions, and some general considerations are listed to facilitate the design of experiments. Air breathing is believed to have evolved in response to aquatic hypoxia and, probably, associated hypercapnia. The review ends by considering what realistic hypercapnia is, how hypercapnic tropical waters can become and how this might influence bimodal animals' gas exchange.
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Affiliation(s)
- S Lefevre
- Department of Biosciences, The Faculty of Mathematics and Natural Sciences, University of Oslo, P. O. Box 1066, 0316 Oslo, Norway
| | - M Bayley
- Zoophysiology, Aarhus University, Department of Bioscience, C. F. Møllers Allé 3, 8000 Aarhus C, Denmark
| | - D J McKenzie
- UMR 9190 Centre for Marine Biodiversity Exploitation and Conservation, Université Montpellier 2, Place Eugène Bataillon, 34095 Montpellier cedex 5, France
- Department of Physiological Sciences, Federal University of São Carlos, SP, Brazil
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15
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Urbina MA, Walsh PJ, Hill JV, Glover CN. Physiological and biochemical strategies for withstanding emersion in two galaxiid fishes. Comp Biochem Physiol A Mol Integr Physiol 2014; 176:49-58. [DOI: 10.1016/j.cbpa.2014.07.006] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2014] [Revised: 06/30/2014] [Accepted: 07/03/2014] [Indexed: 11/28/2022]
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16
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Shartau RB, Brauner CJ. Acid-base and ion balance in fishes with bimodal respiration. JOURNAL OF FISH BIOLOGY 2014; 84:682-704. [PMID: 24502749 DOI: 10.1111/jfb.12310] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
The evolution of air breathing during the Devonian provided early fishes with bimodal respiration with a stable O2 supply from air. This was, however, probably associated with challenges and trade-offs in terms of acid-base balance and ionoregulation due to reduced gill:water interaction and changes in gill morphology associated with air breathing. While many aspects of acid-base and ionoregulation in air-breathing fishes are similar to water breathers, the specific cellular and molecular mechanisms involved remain largely unstudied. In general, reduced ionic permeability appears to be an important adaptation in the few bimodal fishes investigated but it is not known if this is a general characteristic. The kidney appears to play an important role in minimizing ion loss to the freshwater environment in the few species investigated, and while ion uptake across the gut is probably important, it has been largely unexplored. In general, air breathing in facultative air-breathing fishes is associated with an acid-base disturbance, resulting in an increased partial pressure of arterial CO2 and a reduction in extracellular pH (pHE ); however, several fishes appear to be capable of tightly regulating tissue intracellular pH (pHI ), despite a large sustained reduction in pHE , a trait termed preferential pHI regulation. Further studies are needed to determine whether preferential pHI regulation is a general trait among bimodal fishes and if this confers reduced sensitivity to acid-base disturbances, including those induced by hypercarbia, exhaustive exercise and hypoxia or anoxia. Additionally, elucidating the cellular and molecular mechanisms may yield insight into whether preferential pHI regulation is a trait ultimately associated with the early evolution of air breathing in vertebrates.
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Affiliation(s)
- R B Shartau
- Department of Zoology, University of British Columbia, 6270 University Blvd., Vancouver, BC, V6T 1Z4 Canada
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17
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Abstract
The evolution of the aspiration pump seen in tetrapod vertebrates from the buccal-pharyngeal force pump seen in air breathing fish and amphibians appears to have first involved the production of active expiration. Active inspiration arose later. This appears to have involved reconfiguration of a parafacial oscillator (now the parafacial respiratory group/retrotrapezoid nucleus (pFRG/RTN)) to produce active expiration, followed by reconfiguration of a paravagal oscillator (now the preBötC) to produce active inspiration. In the ancestral breathing cycle, inspiration follows expiration, which is in turn followed by glottal closure and breath holding. When both rhythms are expressed, as they are in reptiles and birds, and mammals under conditions of elevated respiratory drive, the pFRG/RTN appears to initiate the respiratory cycle. We propose that the coordinated output of this system is a ventilation cycle characterized by four phases. In reptiles, these consist of active inspiration (I), glottal closure (E1), a pause (an apnea or breath hold) (E2), and an active expiration (E3) that initiates the next cycle. In mammals under resting conditions, active expiration (E3) is suppressed and inspiration (I) is followed by airway constriction and diaphragmatic braking (E1) (rather than glottal closure) and a short pause at end-expiration (E2). As respiratory drive increases in mammals, expiratory muscle activity appears. Frequently, it first appears immediately preceding inspiration (E3) just as it does in reptiles. It can also appear in E1, however, and it is not yet clear what mechanisms underlie when and where in the cycle it appears. This may reflect whether the active expiration is recruited to enhance tidal volume, increase breathing frequency, or both.
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Affiliation(s)
- Sarah E M Jenkin
- Department of Zoology, University of British Columbia, Vancouver, British Columbia, Canada
| | - William K Milsom
- Department of Zoology, University of British Columbia, Vancouver, British Columbia, Canada.
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18
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Milsom WK. New insights into gill chemoreception: Receptor distribution and roles in water and air breathing fish. Respir Physiol Neurobiol 2012; 184:326-39. [DOI: 10.1016/j.resp.2012.07.013] [Citation(s) in RCA: 69] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2012] [Revised: 07/15/2012] [Accepted: 07/17/2012] [Indexed: 12/16/2022]
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19
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de Lima Boijink C, Florindo LH, Leite CAC, Kalinin AL, Milsom WK, Rantin FT. Hypercarbic cardiorespiratory reflexes in the facultative air-breathing fish jeju (Hoplerythrinus unitaeniatus): the role of branchial CO2 chemoreceptors. J Exp Biol 2010; 213:2797-807. [DOI: 10.1242/jeb.040733] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
SUMMARY
The aim of the present study was to determine the roles that externally versus internally oriented CO2/H+-sensitive chemoreceptors might play in promoting cardiorespiratory responses to environmental hypercarbia in the air-breathing fish, Hoplerythrinus unitaeniatus (jeju). Fish were exposed to graded hypercarbia (1, 2.5, 5, 10 and 20% CO2) and also to graded levels of environmental acidosis (pH ~7.0, 6.0, 5.8, 5.6, 5.3 and 4.7) equal to the pH levels of the hypercarbic water to distinguish the relative roles of CO2versus H+. We also injected boluses of CO2-equilibrated solutions (5, 10 and 20% CO2) and acid solutions equilibrated to the same pH as the CO2 boluses into the caudal vein (internal) and buccal cavity (external) to distinguish between internal and external stimuli. The putative location of the chemoreceptors was determined by bilateral denervation of branches of cranial nerves IX (glossopharyngeal) and X (vagus) to the gills. The data indicate that the chemoreceptors eliciting bradycardia, hypertension and gill ventilatory responses (increased frequency and amplitude) to hypercarbia are exclusively branchial, externally oriented and respond specifically to changes in CO2 and not H+. Those involved in producing the cardiovascular responses appeared to be distributed across all gill arches while those involved in the gill ventilatory responses were located primarily on the first gill arch. Higher levels of aquatic CO2 depressed gill ventilation and stimulated air breathing. The chemoreceptors involved in producing air breathing in response to hypercarbia also appeared to be branchial, distributed across all gill arches and responded specifically to changes in aquatic CO2. This would suggest that chemoreceptor groups with different orientations (blood versus water) are involved in eliciting air-breathing responses to hypercarbia in jeju.
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Affiliation(s)
- Cheila de Lima Boijink
- Departament of Physiological Sciences, Federal University of São Carlos, 13565-905 São Carlos, SP, Brazil
| | - Luiz Henrique Florindo
- Departament of Zoology and Botany, Aquaculture Center (CAUNESP), São Paulo State University – UNESP, 15054-000, São José do Rio Preto, SP, Brazil
- National Institute of Science and Technology – Comparative Physiology (FAPESP/CNPq), Brazil
| | - Cleo A. Costa Leite
- Departament of Physiological Sciences, Federal University of São Carlos, 13565-905 São Carlos, SP, Brazil
- National Institute of Science and Technology – Comparative Physiology (FAPESP/CNPq), Brazil
| | - Ana Lúcia Kalinin
- Departament of Physiological Sciences, Federal University of São Carlos, 13565-905 São Carlos, SP, Brazil
- National Institute of Science and Technology – Comparative Physiology (FAPESP/CNPq), Brazil
| | - William K. Milsom
- Department of Zoology, University of British Columbia, Vancouver, BC, Canada, V6T 1Z4
| | - Francisco Tadeu Rantin
- Departament of Physiological Sciences, Federal University of São Carlos, 13565-905 São Carlos, SP, Brazil
- National Institute of Science and Technology – Comparative Physiology (FAPESP/CNPq), Brazil
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20
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Milsom WK. The phylogeny of central chemoreception. Respir Physiol Neurobiol 2010; 173:195-200. [PMID: 20594933 DOI: 10.1016/j.resp.2010.05.022] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2010] [Revised: 05/27/2010] [Accepted: 05/27/2010] [Indexed: 11/18/2022]
Abstract
Respiratory chemoreceptors responsive to changes in CO(2)/H(+) appear to be present in all vertebrates from fish to birds and mammals. They appear to have arisen first in the periphery sensitive to the external environment. Thus, in most fish CO(2)/H(+) chemoreceptors reside primarily in the gills and respond to changes in aquatic rather than arterial P(CO)₂ . In the air-breathing tetrapods (amphibians, mammals, reptiles and birds), the branchial arches regress developmentally and the derivatives of the branchial arteries are now exclusively internal. The receptors associated with these arteries now sense only arterial (not environmental) P(CO)₂/pH . Central CO(2)/H(+) chemoreception also appears to have arisen with the advent of air breathing, presumably as a second line of defense. These receptors may have arisen multiple times in association with several (but not all) of the independent origins of air breathing in fishes. There is strong evidence for multiple central sites of CO(2)/H(+) sensing, at least in amphibians and mammals, suggesting that it may not only have originated multiple times in different species but also multiple times within a single species.
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Affiliation(s)
- W K Milsom
- Department of Zoology, University of British Columbia, Vancouver, BC, Canada.
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21
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Gonzalez RJ, Brauner CJ, Wang YX, Richards JG, Patrick ML, Xi W, Matey V, Val AL. Impact of ontogenetic changes in branchial morphology on gill function in Arapaima gigas. Physiol Biochem Zool 2010; 83:322-32. [PMID: 20100089 DOI: 10.1086/648568] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Soon after hatching, the osteoglossid fish Arapaima gigas undergoes a rapid transition from a water breather to an obligate air breather. This is followed by a gradual disappearance of gill lamellae, which leaves smooth filaments with a reduced branchial diffusion capacity due to loss of surface area, and a fourfold increase in diffusion distance. This study evaluated the effects these changes have on gill function by examining two size classes of fish that differ in gill morphology. In comparison to smaller fish (approximately 67.5 g), which still have lamellae, larger fish (approximately 724.2 g) without lamellae took up a slightly greater percentage of O2 across the gills (30.1% vs. 23.9%), which indicates that the morphological changes do not place limitations on O2 uptake in larger fish. Both size groups excreted similar percentages of CO2 across the gills (85%-90%). However, larger fish had higher blood PCO2 (26.51.9 vs. 16.51.5 mmHg) and HCO3(-) (40.2 +/- 2.9 vs. 33.6 +/- 4.5 mmol L(-1)) concentrations and lower blood pH (7.58 +/- 0.01 vs. 7.70 +/- 0.04) than did smaller fish, despite having lower mass-specific metabolisms, suggesting a possible diffusion limitation for CO2 excretion in larger fish. With regard to ion regulation, rates of diffusive Na+ loss were about 3.5 times higher in larger fish than they were in smaller fish, despite the lowered branchial diffusion capacity, and rates of Na+ uptake were higher by about the same amount despite 40% lower activity of branchial Na+/K+-ATPase. Kinetic analysis of Na uptake revealed an extremely low-affinity (K(m) = 587.9 +/- 169.5 micromol L(-1)), low-capacity (J(max) = 265.7 +/- 56.8 nmol g(-1) h(-1)) transport system. These data may reflect a general reduction in the role of the gills in ion balance. Renal Na+/K+-ATPase activity was 5-10 times higher than Na+/K+-ATPase activity in the gills, and urine: plasma ratios for Na+ and Cl(-) were very low (0.001-0.005) relative to that of other fish, which suggested an increased role for dietary salt intake and renal salt retention and which was representative of a more "terrestrial" mode of ion regulation. Such de-emphasis of branchial ion regulation confers greatly reduced sensitivity of diffusive ion loss to low water pH. Ammonia excretion also appeared to be impacted by gill changes. Rates of ammonia excretion in larger fish were one third less than that in smaller fish, despite larger fish having blood ammonia concentrations that were twice as high.
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Affiliation(s)
- R J Gonzalez
- Department of Biology, University of San Diego, 5998 Alcalá Park, San Diego, California 92110, USA.
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22
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Richards JG. Metabolic Rate Suppression as a Mechanism for Surviving Environmental Challenge in Fish. AESTIVATION 2010; 49:113-39. [DOI: 10.1007/978-3-642-02421-4_6] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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23
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Patel M, Iftikar FI, Smith RW, Ip YK, Wood CM. Water balance and renal function in two species of African lungfish Protopterus dolloi and Protopterus annectens. Comp Biochem Physiol A Mol Integr Physiol 2009; 152:149-57. [DOI: 10.1016/j.cbpa.2008.09.014] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2008] [Revised: 09/10/2008] [Accepted: 09/11/2008] [Indexed: 10/21/2022]
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24
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Zaccone G, Mauceri A, Maisano M, Fasulo S. Innervation of lung and heart in the ray-finned fish, bichirs. Acta Histochem 2009; 111:217-29. [PMID: 19121535 DOI: 10.1016/j.acthis.2008.11.013] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Anatomical and functional studies of the autonomic innervation in the lung and the heart of the bichirs are lacking. The present review paper describes the presence of nerve fibers located in the muscle layers of the lung and its submucosa, the collection of unipolar neurons found in the submucosal and muscle layers of the glottis in a bichir species (Polypterus bichir bichir). Putative oxygen chemoreceptive, neuroepithelial cells (NECs) in the lung mucosa are also included. The latter share many immunohistochemical characteristics similar to those observed in the carotid body and neuroepithelial bodies of mammals. A packed collection of paraganglion cells is located within the trunk of the pulmonary vagus nerves. The paper also examines the occurrence of intracardiac neurons and nerve fibers in the heart of the above species. These studies show that various neurotransmitters may indicate different patterns of innervation in the lung and the heart of the bichirs. However, there is still much to be discovered about the lung and cardiovascular nervous control of these primitive fishes.
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25
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Frick NT, Bystriansky JS, Ip YK, Chew SF, Ballantyne JS. Lipid, ketone body and oxidative metabolism in the African lungfish, Protopterus dolloi following 60 days of fasting and aestivation. Comp Biochem Physiol A Mol Integr Physiol 2008; 151:93-101. [DOI: 10.1016/j.cbpa.2008.06.004] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2008] [Revised: 06/03/2008] [Accepted: 06/04/2008] [Indexed: 10/21/2022]
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26
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Iftikar FI, Patel M, Ip YK, Wood CM. The influence of feeding on aerial and aquatic oxygen consumption, nitrogenous waste excretion, and metabolic fuel usage in the African lungfish, Protopterus annectens. CAN J ZOOL 2008. [DOI: 10.1139/z08-052] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
We studied the utilization of air versus water as a respiratory medium for O2consumption (Mo2) in the bimodally breathing African lungfish, Protopterus annectens (Owen, 1839), (151.2 ± 3.7 g) at 26–28 °C. We also investigated the impact of a single meal on this respiratory allocation and nitrogenous waste excretion in lungfish entrained to a 48 h feeding cycle. Correction for the “microbial blank” was found to be critically important in assessing the aquatic component of Mo2. After correction, total Mo2was low (~1000 μmol·kg–1·h–1), and lungfish took about 40% of Mo2from water and 60% from air. Following a meal of chironomid larvae (3.3% of body mass), Mo2values from both air and water increased in proportion over the first 3 h and continued to increase to a peak at 5–8 h postfeeding, at which point total Mo2(still 40% from water) was approximately 2.5-fold greater than the prefeeding level. When the same fish, entrained to the same 48 h feeding regime, were fasted, Mo2declined then later increased prior to the next anticipated feeding. In fed fish, the elevation in Mo2relative to fasted values was approximately 3-fold at 0–3 h and 9-fold at 5–8 h. This specific dynamic action (SDA) effect lasted until 23–26 h and amounted to only 9.5% of the oxycalorific content of the ingested meal. N-waste efflux was only slightly elevated after feeding, where there was a tendency for greater urea–N excretion (significant at 42–48 h); however, the lungfish remained ammoniotelic overall during the 48 h postfeeding period.
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Affiliation(s)
- F. I. Iftikar
- Department of Biology, McMaster University, Hamilton, ON L8S 4K1, Canada
- Department of Biological Sciences, National University of Singapore, 10 Kent Ridge Road, Singapore 117543, Republic of Singapore
| | - M. Patel
- Department of Biology, McMaster University, Hamilton, ON L8S 4K1, Canada
- Department of Biological Sciences, National University of Singapore, 10 Kent Ridge Road, Singapore 117543, Republic of Singapore
| | - Y. K. Ip
- Department of Biology, McMaster University, Hamilton, ON L8S 4K1, Canada
- Department of Biological Sciences, National University of Singapore, 10 Kent Ridge Road, Singapore 117543, Republic of Singapore
| | - C. M. Wood
- Department of Biology, McMaster University, Hamilton, ON L8S 4K1, Canada
- Department of Biological Sciences, National University of Singapore, 10 Kent Ridge Road, Singapore 117543, Republic of Singapore
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27
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Amelio D, Garofalo F, Brunelli E, Loong AM, Wong WP, Ip YK, Tota B, Cerra MC. Differential NOS expression in freshwater and aestivating Protopterus dolloi (lungfish): Heart vs kidney readjustments. Nitric Oxide 2008; 18:1-10. [DOI: 10.1016/j.niox.2007.10.004] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2007] [Revised: 10/18/2007] [Accepted: 10/19/2007] [Indexed: 10/22/2022]
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28
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Perry S, Euverman R, Wang T, Loong A, Chew S, Ip Y, Gilmour K. Control of breathing in African lungfish (Protopterus dolloi): A comparison of aquatic and cocooned (terrestrialized) animals. Respir Physiol Neurobiol 2008; 160:8-17. [DOI: 10.1016/j.resp.2007.06.015] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2007] [Revised: 06/28/2007] [Accepted: 06/29/2007] [Indexed: 11/15/2022]
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29
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Loong AM, Pang CYM, Hiong KC, Wong WP, Chew SF, Ip YK. Increased urea synthesis and/or suppressed ammonia production in the African lungfish, Protopterus annectens, during aestivation in air or mud. J Comp Physiol B 2007; 178:351-63. [DOI: 10.1007/s00360-007-0228-6] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2007] [Revised: 11/18/2007] [Accepted: 11/22/2007] [Indexed: 10/22/2022]
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30
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Gilmour KM, Euverman RM, Esbaugh AJ, Kenney L, Chew SF, Ip YK, Perry SF. Mechanisms of acid–base regulation in the African lungfishProtopterus annectens. J Exp Biol 2007; 210:1944-59. [PMID: 17515420 DOI: 10.1242/jeb.02776] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
SUMMARYAfrican lungfish Protopterus annectens utilized both respiratory and metabolic compensation to restore arterial pH to control levels following the imposition of a metabolic acidosis or alkalosis. Acid infusion (3 mmol kg–1 NH4Cl) to lower arterial pH by 0.24 units increased both pulmonary (by 1.8-fold) and branchial (by 1.7-fold) ventilation frequencies significantly, contributing to 4.8-fold and 1.9-fold increases in,respectively, aerial and aquatic CO2 excretion. This respiratory compensation appeared to be the main mechanism behind the restoration of arterial pH, because even though net acid excretion(JnetH+) increased following acid infusion in 7 of 11 fish, the mean increase in net acid excretion, 184.5±118.5μmol H+ kg–1 h–1 (mean± s.e.m., N=11), was not significantly different from zero. Base infusion (3 mmol kg–1 NaHCO3) to increase arterial pH by 0.29 units halved branchial ventilation frequency, although pulmonary ventilation frequency was unaffected. Correspondingly, aquatic CO2 excretion also fell significantly (by 3.7-fold) while aerial CO2 excretion was unaffected. Metabolic compensation consisting of negative net acid excretion (net base excretion) accompanied this respiratory compensation, with JnetH+ decreasing from 88.5±75.6 to –337.9±199.4 μmol H+kg–1 h–1 (N=8). Partitioning of net acid excretion into renal and extra-renal (assumed to be branchial and/or cutaneous) components revealed that under control conditions, net acid excretion occurred primarily by extra-renal routes. Finally, several genes that are involved in the exchange of acid–base equivalents between the animal and its environment (carbonic anhydrase, V-type H+-ATPase and Na+/HCO –3 cotransporter) were cloned, and their branchial and renal mRNA expressions were examined prior to and following acid or base infusion. In no case was mRNA expression significantly altered by metabolic acid–base disturbance. These findings suggest that lungfish, like tetrapods, alter ventilation to compensate for metabolic acid–base disturbances, a mechanism that is not employed by water-breathing fish. Like fish and amphibians, however, extra-renal routes play a key role in metabolic compensation.
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Affiliation(s)
- K M Gilmour
- Department of Biology and Centre for Advanced Research in Environmental Genomics, University of Ottawa, Ottawa, ON, Canada.
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31
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Wilkie MP, Morgan TP, Galvez F, Smith RW, Kajimura M, Ip YK, Wood CM. The African Lungfish (Protopterus dolloi): Ionoregulation and Osmoregulation in a Fish out of Water. Physiol Biochem Zool 2007; 80:99-112. [PMID: 17160883 DOI: 10.1086/508837] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/28/2006] [Indexed: 11/04/2022]
Abstract
Although urea production and metabolism in lungfish have been thoroughly studied, we have little knowledge of how internal osmotic and electrolyte balance are controlled during estivation or in water. We tested the hypothesis that, compared with the body surface of teleosts, the slender African lungfish (Protopterus dolloi) body surface was relatively impermeable to water, Na(+), and Cl(-) due to its greatly reduced gills. Accordingly, we measured the tritiated water ((3)H-H(2)O) flux in P. dolloi in water and during air exposure. In water, (3)H-H(2)O efflux was comparable with the lowest measurements reported in freshwater teleosts, with a rate constant (K) of 17.6% body water h(-1). Unidirectional ion fluxes, measured using (22)Na(+) and (36)Cl(-), indicated that Na(+) and Cl(-) influx was more than 90% lower than values reported in most freshwater teleosts. During air exposure, a cocoon formed within 1 wk that completely covered the dorsolateral body surface. However, there were no disturbances to blood osmotic or ion (Na(+), Cl(-)) balance, despite seven- to eightfold increases in plasma urea after 20 wk. Up to 13-fold increases in muscle urea (on a dry-weight basis) were the likely explanation for the 56% increase in muscle water content observed after 20 wk of air exposure. The possibility that muscle acted as a "water reservoir" during air exposure was supported by the 20% decline in body mass observed during subsequent reimmersion in water. This decline in body mass was equivalent to 28 mL water in a 100-g animal and was very close to the calculated net water gain (approximately 32 mL) observed during the 20-wk period of air exposure. Tritiated water and unidirectional ion fluxes on air-exposed lungfish revealed that the majority of water and ion exchange was via the ventral body surface at rates that were initially similar to aquatic rates. The (3)H-H(2)O flux declined over time but increased upon reimmersion. We conclude that the slender lungfish body surface, including the gills, has relatively low permeability to water and ions but that the ventral surface is an important site of osmoregulation and ionoregulation. We further propose that an amphibian-like combination of ventral skin water and ion permeability, plus internal urea accumulation during air exposure, allows P. dolloi to extract water from its surroundings and to store water in the muscle when the water supply becomes limited.
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Affiliation(s)
- Michael P Wilkie
- Department of Biology, McMaster University, Hamilton, Ontario, Canada.
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Perry SF, Gilmour KM. Acid-base balance and CO2 excretion in fish: unanswered questions and emerging models. Respir Physiol Neurobiol 2006; 154:199-215. [PMID: 16777496 DOI: 10.1016/j.resp.2006.04.010] [Citation(s) in RCA: 181] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2005] [Revised: 04/14/2006] [Accepted: 04/15/2006] [Indexed: 11/22/2022]
Abstract
Carbon dioxide (CO(2)) excretion and acid-base regulation in fish are linked, as in other animals, though the reversible reactions of CO(2) and the acid-base equivalents H(+) and HCO(3)(-): CO(2)+H(2)O<-->H(+)+HCO(3)(-). These relationships offer two potential routes through which acid-base disturbances may be regulated. Respiratory compensation involves manipulation of ventilation so as to retain CO(2) or enhance CO(2) loss, with the concomitant readjustment of the CO(2) reaction equilibrium and the resultant changes in H(+) levels. In metabolic compensation, rates of direct H(+) and HCO(3)(-) exchange with the environment are manipulated to achieve the required regulation of pH; in this case, hydration of CO(2) yields the necessary H(+) and HCO(3)(-) for exchange. Because ventilation in fish is keyed primarily to the demands of extracting O(2) from a medium of low O(2) content, the capacity to utilize respiratory compensation of acid-base disturbances is limited and metabolic compensation across the gill is the primary mechanism for re-establishing pH balance. The contribution of branchial acid-base exchanges to pH compensation is widely recognized, but the molecular mechanisms underlying these exchanges remain unclear. The relatively recent application of molecular approaches to this question is generating data, sometimes conflicting, from which models of branchial acid-base exchange are gradually emerging. The critical importance of the gill in acid-base compensation in fish, however, has made it easy to overlook other potential contributors. Recently, attention has been focused on the role of the kidney and particularly the molecular mechanisms responsible for HCO(3)(-) reabsorption. It is becoming apparent that, at least in freshwater fish, the responses of the kidney are both flexible and essential to complement the role of the gill in metabolic compensation. Finally, while respiratory compensation in fish is usually discounted, the few studies that have thoroughly characterized ventilatory responses during acid-base disturbances in fish suggest that breathing may, in fact, be adjusted in response to pH imbalances. How this is accomplished and the role it plays in re-establishing acid-base balance are questions that remain to be answered.
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Affiliation(s)
- S F Perry
- Department of Biology and Centre for Advanced Research in Environmental Genomics, University of Ottawa, 30 Marie Curie, Ottawa, Ont., Canada.
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