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Rzhechitskiy Y, Gurkov A, Bolbat N, Shchapova E, Nazarova A, Timofeyev M, Borvinskaya E. Adipose Fin as a Natural “Optical Window” for Implantation of Fluorescent Sensors into Salmonid Fish. Animals (Basel) 2022; 12:ani12213042. [PMID: 36359166 PMCID: PMC9654777 DOI: 10.3390/ani12213042] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2022] [Revised: 10/27/2022] [Accepted: 11/03/2022] [Indexed: 11/09/2022] Open
Abstract
Simple Summary Novel optical sensors require implantation into the most transparent organs in order to ensure the most reliable and rapid monitoring of animal health. Widely farmed salmonid fish, such as rainbow trout, have highly translucent adipose fin, which we tested here and showed its high potential as the implantation site for the fluorescent sensors. The filamentous sensors were convenient to inject into the fin, and their optical signal was easily detectable using a simple hand-held device even without immobilization of the fish. Responsiveness of the sensors inside the adipose fin to bodily changes was shown under induced acidosis of fish fluids. The obtained results characterize adipose fin as the favorable site for implantation of optical sensors into salmonids for real-time tracking animal physiological status in basic research and aquaculture. Abstract Implantable optical sensors are emerging tools that have the potential to enable constant real-time monitoring of various internal physiological parameters. Such a possibility will open new horizons for health control not only in medicine, but also in animal husbandry, including aquaculture. In this study, we analyze different organs of commonly farmed rainbow trout (Oncorhynchus mykiss) as implantation sites for fluorescent sensors and propose the adipose fin, lacking an endoskeleton, as the optimal choice. The fin is highly translucent due to significantly thinner dermis, which makes the detectable fluorescence of an implanted sensor operating at the visible light range by more than an order of magnitude higher relative to the skin. Compared to the proximal parts of ray fins, the adipose fin provides easy implantation and visualization of the sensor. Finally, we tested fluorescent pH sensors inside the adipose fin and demonstrated the possibility of acquiring their signal with a simple hand-held device and without fish anesthesia. All these features will most likely make the adipose fin the main “window” into the internal physiological processes of salmonid fish with the help of implantable optical sensors.
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Affiliation(s)
| | - Anton Gurkov
- Institute of Biology, Irkutsk State University, 664025 Irkutsk, Russia
- Baikal Research Centre, 664003 Irkutsk, Russia
| | - Nadezhda Bolbat
- Institute of Biology, Irkutsk State University, 664025 Irkutsk, Russia
| | - Ekaterina Shchapova
- Institute of Biology, Irkutsk State University, 664025 Irkutsk, Russia
- Baikal Research Centre, 664003 Irkutsk, Russia
| | - Anna Nazarova
- Institute of Biology, Irkutsk State University, 664025 Irkutsk, Russia
| | - Maxim Timofeyev
- Institute of Biology, Irkutsk State University, 664025 Irkutsk, Russia
| | - Ekaterina Borvinskaya
- Institute of Biology, Irkutsk State University, 664025 Irkutsk, Russia
- Correspondence:
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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. Using the swimbladder as a respiratory organ and/or a buoyancy structure-Benefits and consequences. JOURNAL OF EXPERIMENTAL ZOOLOGY. PART A, ECOLOGICAL AND INTEGRATIVE PHYSIOLOGY 2021; 335:831-842. [PMID: 33830682 DOI: 10.1002/jez.2460] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/02/2021] [Revised: 03/16/2021] [Accepted: 03/22/2021] [Indexed: 11/07/2022]
Abstract
A swimbladder is a special organ present in several orders of Actinopterygians. As a gas-filled cavity it contributes to a reduction in overall density, but on descend from the water surface its contribution as a buoyancy device is very limited because the swimbladder is compressed by increasing hydrostatic pressure. It serves, however, as a very efficient organ for aerial gas exchange. To avoid the loss of oxygen to hypoxic water at the gills many air-breathing fish show a reduced gill surface area. This, in turn, also reduces surface area available for other functions, so that breathing air is connected to a number of physiological adjustments with respect to ion homeostasis, acid-base regulation and nitrogen excretion. Using the swimbladder as a buoyancy structure resulted in the loss of its function as an air-breathing organ and required the development of a gas secreting mechanism. This was achieved via the Root effect and a countercurrent arrangement of the blood supply to the swimbladder. In addition, a detachable air space with separated blood supply was necessary to allow the resorption of gas from the swimbladder. Gas secretion as well as gas resorption are slow phenomena, so that rapid changes in depth cannot instantaneously be compensated by appropriate volume changes. As gas-filled cavities the respiratory swimbladder and the buoyancy device require surfactant. Due to high oxygen partial pressures inside the bladder air-exposed tissues need an effective reactive oxygen species defense system, which is particularly important for a swimbladder at depth.
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Affiliation(s)
- Bernd Pelster
- Institute of Zoology, University of Innsbruck, Innsbruck, Austria
- Center for Molecular Biosciences, University Innsbruck, Innsbruck, Austria
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4
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Andersen NCM, Fago A, Damsgaard C. Evolution of hemoglobin function in tropical air-breathing catfishes. JOURNAL OF EXPERIMENTAL ZOOLOGY. PART A, ECOLOGICAL AND INTEGRATIVE PHYSIOLOGY 2021; 335:814-819. [PMID: 34254462 DOI: 10.1002/jez.2504] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/16/2021] [Revised: 06/18/2021] [Accepted: 06/23/2021] [Indexed: 11/08/2022]
Abstract
The evolution of hemoglobin function in the transition from water- to air-breathing has been highly debated but remains unresolved. Here, we characterized the hemoglobin function in five closely related water- and air-breathing catfishes. We identify distinct directions of hemoglobin evolution in the clades that evolved air-breathing, and we show strong selection on hemoglobin function within the catfishes. These findings show that the lack of a general direction in hemoglobin function in the transition from water- to air-breathing may have resulted from divergent selection on hemoglobin function in independent clades of air-breathing fishes.
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Affiliation(s)
| | - Angela Fago
- Section for Zoophysiology, Department of Biology, Aarhus University, Aarhus C, Denmark
| | - Christian Damsgaard
- Section for Zoophysiology, Department of Biology, Aarhus University, Aarhus C, Denmark.,Aarhus Institute of Advanced Studies, Aarhus University, Aarhus C, Denmark
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5
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Frommel AY, Kwan GT, Prime KJ, Tresguerres M, Lauridsen H, Val AL, Gonçalves LU, Brauner CJ. Changes in gill and air-breathing organ characteristics during the transition from water- to air-breathing in juvenile Arapaima gigas. JOURNAL OF EXPERIMENTAL ZOOLOGY PART 2021; 335:801-813. [PMID: 33819380 DOI: 10.1002/jez.2456] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/29/2020] [Revised: 02/10/2021] [Accepted: 02/25/2021] [Indexed: 01/01/2023]
Abstract
The obligate air-breathing Amazonian fish, Arapaima gigas, hatch as water-breathing larvae but with development, they modify their swim bladder to an air-breathing organ (ABO) while reducing their gill filaments to avoid oxygen loss. Here, we show that significant changes already take place between 4 weeks (1.6 g) and 11 weeks (5 g) post hatch, with a reduction in gill lamellar surface area, increase in gill diffusion distance, and proliferation of the parenchyma in the ABO. By using a variety of methods, we quantified the surface area and diffusion distances of the gills and skin, and the swim bladder volume and anatomical complexity from hatch to 11-week-old juveniles. In addition, we identified the presence of two ionocyte types in the gills and show how these change with development. Until 1.6 g, A. gigas possess only the H+ -excreting/Na+ -absorbing type, while 5-g fish and adults have an additional ionocyte which likely absorbs H+ and Cl- and excretes HCO3 - . The ionocyte density on the gill filaments increased with age and is likely a compensatory mechanism for maintaining ion transport while reducing gill surface area. In the transition from water- to air-breathing, A. gigas likely employs a trimodal respiration utilizing gills, skin, and ABO and thus avoid a respiratory-ion regulatory compromise at the gills.
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Affiliation(s)
- Andrea Y Frommel
- Department of Zoology, University of British Columbia, Vancouver, British Columbia, Canada.,Institute of Oceans and Fisheries, University of British Columbia, Vancouver, British Columbia, Canada
| | - Garfield T Kwan
- Marine Biology Research Division, Scripps Institution of Oceanography, University of California San Diego, La Jolla, California, USA
| | - Kaelan J Prime
- Marine Biology Research Division, Scripps Institution of Oceanography, University of California San Diego, La Jolla, California, USA
| | - Martin Tresguerres
- Marine Biology Research Division, Scripps Institution of Oceanography, University of California San Diego, La Jolla, California, USA
| | - Henrik Lauridsen
- Department of Clinical Medicine (Comparative Medicine Lab), Aarhus University, Aarhus, Denmark
| | - Adalberto L Val
- Brazilian National Institute for Research of the Amazon, Manaus, Amazonas, Brazil
| | - Ligia U Gonçalves
- Brazilian National Institute for Research of the Amazon, Manaus, Amazonas, Brazil
| | - Colin J Brauner
- Department of Zoology, University of British Columbia, Vancouver, British Columbia, Canada
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Survival, Growth, and Development in the Early Stages of the Tropical Gar Atractosteus tropicus: Developmental Critical Windows and the Influence of Temperature, Salinity, and Oxygen Availability. FISHES 2021. [DOI: 10.3390/fishes6010005] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Alterations in fish developmental trajectories occur in response to genetic and environmental changes, especially during sensitive periods of development (critical windows). Embryos and larvae of Atractosteus tropicus were used as a model to study fish survival, growth, and development as a function of temperature (28 °C control, 33 °C, and 36 °C), salinity (0.0 ppt control, 4.0 ppt, and 6.0 ppt), and air saturation (control ~95% air saturation, hypoxia ~30% air saturation, and hyperoxia ~117% air saturation) during three developmental periods: (1) fertilization to hatch, (2) day 1 to day 6 post hatch (dph), and (3) 7 to 12 dph. Elevated temperature, hypoxia, and hyperoxia decreased survival during incubation, and salinity at 2 and 3 dph. Growth increased in embryos incubated at elevated temperature, at higher salinity, and in hyperoxia but decreased in hypoxia. Changes in development occurred as alterations in the timing of hatching, yolk depletion, acceptance of exogenous feeding, free swimming, and snout shape change, especially at high temperature and hypoxia. Our results suggest identifiable critical windows of development in the early ontogeny of A. tropicus and contribute to the knowledge of fish larval ecology and the interactions of individuals × stressors × time of exposure.
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7
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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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8
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Shartau RB, Baker DW, Harter TS, Aboagye DL, Allen PJ, Val AL, Crossley DA, Kohl ZF, Hedrick MS, Damsgaard C, Brauner CJ. Preferential intracellular pH regulation is a common trait amongst fishes exposed to high environmental CO 2. J Exp Biol 2020; 223:jeb208868. [PMID: 32127382 DOI: 10.1242/jeb.208868] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2019] [Accepted: 02/25/2020] [Indexed: 12/13/2022]
Abstract
Acute (<96 h) exposure to elevated environmental CO2 (hypercarbia) induces a pH disturbance in fishes that is often compensated by concurrent recovery of intracellular and extracellular pH (pHi and pHe, respectively; coupled pH regulation). However, coupled pH regulation may be limited at CO2 partial pressure (PCO2 ) tensions far below levels that some fishes naturally encounter. Previously, four hypercarbia-tolerant fishes had been shown to completely and rapidly regulate heart, brain, liver and white muscle pHi during acute exposure to >4 kPa PCO2 (preferential pHi regulation) before pHe compensation was observed. Here, we test the hypothesis that preferential pHi regulation is a widespread strategy of acid-base regulation among fish by measuring pHi regulation in 10 different fish species that are broadly phylogenetically separated, spanning six orders, eight families and 10 genera. Contrary to previous views, we show that preferential pHi regulation is the most common strategy for acid-base regulation within these fishes during exposure to severe acute hypercarbia and that this strategy is associated with increased hypercarbia tolerance. This suggests that preferential pHi regulation may confer tolerance to the respiratory acidosis associated with hypercarbia, and we propose that it is an exaptation that facilitated key evolutionary transitions in vertebrate evolution, such as the evolution of air breathing.
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Affiliation(s)
- R B Shartau
- Department of Zoology, University of British Columbia, Vancouver, BC, Canada V6T 1Z4
| | - D W Baker
- Department of Fisheries and Aquaculture, Vancouver Island University, Nanaimo, BC, Canada V9R 5S5
| | - T S Harter
- Department of Zoology, University of British Columbia, Vancouver, BC, Canada V6T 1Z4
| | - D L Aboagye
- Department of Wildlife, Fisheries and Aquaculture, Mississippi State University, Starkville, MS 39759, USA
| | - P J Allen
- Department of Wildlife, Fisheries and Aquaculture, Mississippi State University, Starkville, MS 39759, USA
| | - A L Val
- Laboratory of Ecophysiology and Molecular Evolution, Brazilian National Institute for Research of the Amazon (INPA), Manaus, AM CEP 69080-971, Brazil
| | - D A Crossley
- Department of Biological Sciences, University of North Texas, Denton, TX 76203-5017, USA
| | - Z F Kohl
- Department of Biological Sciences, University of North Texas, Denton, TX 76203-5017, USA
| | - M S Hedrick
- Department of Biological Sciences, California State University, East Bay, CA 94542, USA
| | - C Damsgaard
- Department of Zoology, University of British Columbia, Vancouver, BC, Canada V6T 1Z4
| | - C J Brauner
- Department of Zoology, University of British Columbia, Vancouver, BC, Canada V6T 1Z4
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9
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Damsgaard C, Baliga VB, Bates E, Burggren W, McKenzie DJ, Taylor E, Wright PA. Evolutionary and cardio-respiratory physiology of air-breathing and amphibious fishes. Acta Physiol (Oxf) 2020; 228:e13406. [PMID: 31630483 DOI: 10.1111/apha.13406] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2019] [Revised: 09/28/2019] [Accepted: 10/17/2019] [Indexed: 12/24/2022]
Abstract
Air-breathing and amphibious fishes are essential study organisms to shed insight into the required physiological shifts that supported the full transition from aquatic water-breathing fishes to terrestrial air-breathing tetrapods. While the origin of air-breathing in the evolutionary history of the tetrapods has received considerable focus, much less is known about the evolutionary physiology of air-breathing among fishes. This review summarizes recent advances within the field with specific emphasis on the cardiorespiratory regulation associated with air-breathing and terrestrial excursions, and how respiratory physiology of these living transitional forms are affected by development and personality. Finally, we provide a detailed and re-evaluated model of the evolution of air-breathing among fishes that serves as a framework for addressing new questions on the cardiorespiratory changes associated with it. This review highlights the importance of combining detailed studies on piscine air-breathing model species with comparative multi-species studies, to add an additional dimension to our understanding of the evolutionary physiology of air-breathing in vertebrates.
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Affiliation(s)
| | - Vikram B. Baliga
- Department of Zoology University of British Columbia Vancouver BC Canada
| | - Eric Bates
- Derailleur Interactive Vancouver BC Canada
| | - Warren Burggren
- Department of Biological Sciences University of North Texas Denton TX USA
| | - David J. McKenzie
- UMR Marbec, CNRS, IRD, Ifremer Université Montpellier Montpellier France
| | - Edwin Taylor
- School of Biosciences University of Birmingham Birmingham UK
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10
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Gam LTH, Thanh Huong DT, Tuong DD, Phuong NT, Jensen FB, Wang T, Bayley M. Effects of temperature on acid-base regulation, gill ventilation and air breathing in the clown knifefish, Chitala ornata. J Exp Biol 2020; 223:jeb216481. [PMID: 32001546 DOI: 10.1242/jeb.216481] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2019] [Accepted: 01/23/2020] [Indexed: 11/20/2022]
Abstract
Chitala ornata is a facultative air-breathing fish, which at low temperatures shows an arterial PCO2 (PaCO2 ) level only slightly elevated above that of water breathers. By holding fish with in-dwelling catheters at temperatures from 25 to 36°C and measuring blood gasses, we show that this animal follows the ubiquitous poikilotherm pattern of reducing arterial pH with increasing temperature. Surprisingly, the temperature increase caused an elevation of PaCO2 from 5 to 12 mmHg while the plasma bicarbonate concentration remained constant at around 8 mmol l-1 The temperature increase also gave rise to a larger fractional increase in air breathing than in gill ventilation frequency. These findings suggest that air breathing, and hence the partitioning of gas exchange, is to some extent regulated by acid-base status in air-breathing fish and that these bimodal breathers will be increasingly likely to adopt respiratory pH control as temperature rises, providing an interesting avenue for future research.
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Affiliation(s)
- Le Thi Hong Gam
- College of Aquaculture and Fisheries, Can Tho University, Can Tho City, Vietnam
| | - Do Thi Thanh Huong
- College of Aquaculture and Fisheries, Can Tho University, Can Tho City, Vietnam
| | - Dang Diem Tuong
- College of Aquaculture and Fisheries, Can Tho University, Can Tho City, Vietnam
| | - Nguyen Thanh Phuong
- College of Aquaculture and Fisheries, Can Tho University, Can Tho City, Vietnam
| | - Frank Bo Jensen
- Department of Biology, University of Southern Denmark, 5230 Odense, Denmark
| | - Tobias Wang
- Zoophysiology, Department of Bioscience, Aarhus University, 8000 Aarhus, Denmark
- Aarhus Institute of Advanced Studies, 8000 Aarhus C, Denmark
| | - Mark Bayley
- Zoophysiology, Department of Bioscience, Aarhus University, 8000 Aarhus, Denmark
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11
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Storz JF, Natarajan C, Grouleff MK, Vandewege M, Hoffmann FG, You X, Venkatesh B, Fago A. Oxygenation properties of hemoglobin and the evolutionary origins of isoform multiplicity in an amphibious air-breathing fish, the blue-spotted mudskipper ( Boleophthalmus pectinirostris). ACTA ACUST UNITED AC 2020; 223:jeb.217307. [PMID: 31836650 DOI: 10.1242/jeb.217307] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2019] [Accepted: 12/09/2019] [Indexed: 12/13/2022]
Abstract
Among the numerous lineages of teleost fish that have independently transitioned from obligate water breathing to facultative air breathing, evolved properties of hemoglobin (Hb)-O2 transport may have been shaped by the prevalence and severity of aquatic hypoxia (which influences the extent to which fish are compelled to switch to aerial respiration) as well as the anatomical design of air-breathing structures and the cardiovascular system. Here, we examined the structure and function of Hbs in an amphibious, facultative air-breathing fish, the blue-spotted mudskipper (Boleophthalmus pectinirostris). We also characterized the genomic organization of the globin gene clusters of the species and we integrated phylogenetic and comparative genomic analyses to unravel the duplicative history of the genes that encode the subunits of structurally distinct mudskipper Hb isoforms (isoHbs). The B. pectinirostris isoHbs exhibit high intrinsic O2 affinities, similar to those of hypoxia-tolerant, water-breathing teleosts, and remarkably large Bohr effects. Genomic analysis of conserved synteny revealed that the genes that encode the α-type subunits of the two main adult isoHbs are members of paralogous gene clusters that represent products of the teleost-specific whole-genome duplication. Experiments revealed no appreciable difference in the oxygenation properties of co-expressed isoHbs in spite of extensive amino acid divergence between the alternative α-chain subunit isoforms. It therefore appears that the ability to switch between aquatic and aerial respiration does not necessarily require a division of labor between functionally distinct isoHbs with specialized oxygenation properties.
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Affiliation(s)
- Jay F Storz
- School of Biological Sciences, University of Nebraska, Lincoln, NE 68588, USA
| | | | - Magnus K Grouleff
- Zoophysiology, Department of Biology, Aarhus University, C. F. Møllers Alle 3, Aarhus C 8000, Denmark
| | - Michael Vandewege
- Department of Biochemistry, Molecular Biology, Entomology, and Plant Pathology, Mississippi State University, Mississippi State, MS 39762, USA.,Institute for Genomics, Biocomputing, and Biotechnology, Mississippi State University, Mississippi State, MS 39762, USA
| | - Federico G Hoffmann
- Department of Biochemistry, Molecular Biology, Entomology, and Plant Pathology, Mississippi State University, Mississippi State, MS 39762, USA.,Institute for Genomics, Biocomputing, and Biotechnology, Mississippi State University, Mississippi State, MS 39762, USA
| | - Xinxin You
- Shenzhen Key Lab of Marine Genomics, Guangdong Provincial Key Lab of Molecular Breeding in Marine Economic Animals, BGI Academy of Marine Sciences, BGI-Marine, BGI, Shenzhen 518083, China
| | - Byrappa Venkatesh
- Institute of Molecular and Cell Biology, Agency for Science, Technology and Research, 61 Biopolis Drive, Singapore 138673, Singapore.,Department of Pediatrics, Yong Loo Lin School of Medicine, National University of Singapore, Singapore 119228, Singapore
| | - Angela Fago
- Zoophysiology, Department of Biology, Aarhus University, C. F. Møllers Alle 3, Aarhus C 8000, Denmark
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12
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Burggren W, Bautista N. Invited review: Development of acid-base regulation in vertebrates. Comp Biochem Physiol A Mol Integr Physiol 2019; 236:110518. [DOI: 10.1016/j.cbpa.2019.06.018] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2019] [Revised: 06/24/2019] [Accepted: 06/25/2019] [Indexed: 12/26/2022]
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13
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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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14
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Brauner CJ, Shartau RB, Damsgaard C, Esbaugh AJ, Wilson RW, Grosell M. Acid-base physiology and CO2 homeostasis: Regulation and compensation in response to elevated environmental CO2. FISH PHYSIOLOGY 2019. [DOI: 10.1016/bs.fp.2019.08.003] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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15
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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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16
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Sackville MA, Shartau RB, Damsgaard C, Hvas M, Phuong LM, Wang T, Bayley M, Thanh Huong DT, Phuong NT, Brauner CJ. Water pH limits extracellular but not intracellular pH compensation in the CO 2-tolerant freshwater fish Pangasianodon hypophthalmus. ACTA ACUST UNITED AC 2018; 221:jeb.190413. [PMID: 30352827 DOI: 10.1242/jeb.190413] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2018] [Accepted: 10/17/2018] [Indexed: 11/20/2022]
Abstract
Preferentially regulating intracellular pH (pHi) confers exceptional CO2 tolerance on fish, but is often associated with reductions in extracellular pH (pHe) compensation. It is unknown whether these reductions are due to intrinsically lower capacities for pHe compensation, hypercarbia-induced reductions in water pH or other factors. To test how water pH affects capacities and strategies for pH compensation, we exposed the CO2-tolerant fish Pangasianodon hypophthalmus to 3 kPa P CO2 for 20 h at an ecologically relevant water pH of 4.5 or 5.8. Brain, heart and liver pHi was preferentially regulated in both treatments. However, blood pHe compensation was severely reduced at water pH 4.5 but not 5.8. This suggests that low water pH limits acute pHe but not pHi compensation in fishes preferentially regulating pHi Hypercarbia-induced reductions in water pH might therefore underlie the unexplained reductions to pHe compensation in fishes preferentially regulating pHi, and may increase selection for preferential pHi regulation.
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Affiliation(s)
- Michael A Sackville
- Department of Zoology, University of British Columbia, Vancouver, BC, Canada V6T 1Z4
| | - Ryan B Shartau
- Department of Zoology, University of British Columbia, Vancouver, BC, Canada V6T 1Z4
| | | | - Malthe Hvas
- Department of Bioscience, Aarhus University, 8000 Aarhus-C, Denmark
| | - Le My Phuong
- College of Aquaculture and Fisheries, Can Tho University, 92000 Can Tho City, Vietnam
| | - Tobias Wang
- Department of Bioscience, Aarhus University, 8000 Aarhus-C, Denmark
| | - Mark Bayley
- Department of Bioscience, Aarhus University, 8000 Aarhus-C, Denmark
| | - Do Thi Thanh Huong
- College of Aquaculture and Fisheries, Can Tho University, 92000 Can Tho City, Vietnam
| | - Nguyen Thanh Phuong
- College of Aquaculture and Fisheries, Can Tho University, 92000 Can Tho City, Vietnam
| | - Colin J Brauner
- Department of Zoology, University of British Columbia, Vancouver, BC, Canada V6T 1Z4
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17
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Pelster B, Wood CM. Ionoregulatory and oxidative stress issues associated with the evolution of air-breathing. Acta Histochem 2018; 120:667-679. [PMID: 30177382 DOI: 10.1016/j.acthis.2018.08.012] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Aquatic areas frequently face hypoxic conditions. In order to get sufficient oxygen to support aerobic metabolism, a number of freshwater fish resort to aerial respiration to supplement gill respiration especially in situations with reduced oxygen availability in the water. In many species a concomitant reduction in gill surface area or in gill perfusion reduces possible loss of aerially acquired oxygen to the water at the gills, but it also compromises the ion regulatory capacity of gill tissue. In consequence, the reduced gill contact area with water requires appropriate compensation to maintain ion and acid-base homeostasis, often with important ramifications for other organs. Associated modifications in the structure and function of the gills themselves, the skin, the gut, the kidney, and the physiology of water exchange and ion-linked acid-base regulation are discussed. In air-breathing fish, the gut may gain particular importance for the uptake of ions. In addition, tissues frequently exposed to environmental air encounter much higher oxygen partial pressures than typically observed in fish tissues. Physostomous fish using the swimbladder for aerial respiration, for example, will encounter aerial oxygen partial pressure at the swimbladder epithelium when frequently gulping air in hypoxic water. Hyperoxic conditions or rapid changes in oxygen partial pressures result in an increase in the production of reactive oxygen species (ROS). Accordingly, in air-breathing fish, strategies of ionoregulation may be greatly modified, and the ROS defense capacity of air-exposed tissues is improved.
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18
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Shartau R, Crossley D, Kohl Z, Elsey R, Brauner C. American alligator (Alligator mississippiensis) embryos tightly regulate intracellular pH during a severe acidosis. CAN J ZOOL 2018. [DOI: 10.1139/cjz-2017-0249] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Crocodilian nests naturally experience high CO2 (hypercarbia), which leads to increased blood Pco2 and reduced blood pH (pHe) in embryos; their response to acid–base challenges is not known. During acute hypercarbia, snapping turtle embryos preferentially regulate tissue pH (pHi) against pHe reductions. This is proposed to be associated with CO2 tolerance in reptilian embryos and is not found in adults. In the present study, we investigated pH regulation in American alligator (Alligator mississippiensis (Daudin, 1802)) embryos exposed to 1 h of hypercarbia hypoxia (13 kPa Pco2, 9 kPa Po2). Hypercarbia hypoxia reduced pHe by 0.42 pH unit, while heart and brain pHi increased, with no change in the pHi of other tissues. The results indicate that American alligator embryos preferentially regulate pHi, similar to snapping turtle embryos, which represents a markedly different strategy of acid–base regulation than what is observed in adult reptiles. These findings suggest that preferential pHi regulation may be a strategy of acid–base regulation used by embryonic reptiles.
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Affiliation(s)
- R.B. Shartau
- Department of Zoology, The University of British Columbia, Vancouver, BC V6T 1Z4, Canada
| | - D.A. Crossley
- Department of Biological Sciences, University of North Texas, Denton, TX 76203, USA
| | - Z.F. Kohl
- Department of Biological Sciences, University of North Texas, Denton, TX 76203, USA
| | - R.M. Elsey
- Louisiana Department of Wildlife and Fisheries, Rockefeller Wildlife Refuge, Grand Chenier, LA 70643, USA
| | - C.J. Brauner
- Department of Zoology, The University of British Columbia, Vancouver, BC V6T 1Z4, Canada
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19
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Gam LTH, Jensen FB, Huong DTT, Phuong NT, Bayley M. The effects of elevated environmental CO 2 on nitrite uptake in the air-breathing clown knifefish, Chitala ornata. AQUATIC TOXICOLOGY (AMSTERDAM, NETHERLANDS) 2018; 196:124-131. [PMID: 29367072 DOI: 10.1016/j.aquatox.2018.01.011] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/30/2017] [Revised: 01/09/2018] [Accepted: 01/13/2018] [Indexed: 06/07/2023]
Abstract
Nitrite and carbon dioxide are common environmental contaminants in the intensive aquaculture ponds used to farm clown knifefish (Chitala ornata) in the Mekong delta, Vietnam. Here we tested the hypothesis that hypercapnia reduces nitrite uptake across the gills, because pH regulation will reduce chloride uptake and hence nitrite uptake as the two ions compete for the same transport route via the branchial HCO3-/Cl- exchanger. Fish fitted with arterial catheters were exposed to normocapnic/normoxic water (control), nitrite (1 mM), hypercapnia (21 mmHg CO2), or combined hypercapnia (acclimated hypercapnia) and nitrite for 96 h. Blood was sampled to measure acid-base status, haemoglobin derivatives and plasma ions. Plasma nitrite increased for 48 h, but levels stayed below the exposure concentration, and subsequently decreased as a result of nitrite detoxification to nitrate. The total uptake of nitrite (evaluated as [NO2-] + [NO3-]) was significantly decreased in hypercapnia, in accordance with the hypothesis. Methemoglobin and nitrosylhemoglobin levels were similarly lower during hypercapnic compared to normocapnic nitrite exposure. The respiratory acidosis induced by hypercapnia was half-compensated by bicarbonate accumulation in 96 h, which was mainly chloride-mediated (i.e. reduced Cl- influx via the branchial HCO3-/Cl- exchanger). Plasma osmolality and main ions (Na+, Cl-) were significantly decreased by hypercapnia and by nitrite exposure, consistent with inhibition of active transport. We conclude that hypercapnia induces a long-lasting, and mainly chloride-mediated acid-base regulation that reduces the uptake of nitrite across the gills.
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Affiliation(s)
- Le Thi Hong Gam
- College of Aquaculture and Fisheries, Can Tho University, Can Tho City, Viet Nam
| | - Frank Bo Jensen
- Department of Biology, University of Southern Denmark, Odense, Denmark
| | - Do Thi Thanh Huong
- College of Aquaculture and Fisheries, Can Tho University, Can Tho City, Viet Nam
| | - Nguyen Thanh Phuong
- College of Aquaculture and Fisheries, Can Tho University, Can Tho City, Viet Nam
| | - Mark Bayley
- Zoophysiology, Department of Bioscience, Aarhus University, Building 1131 C.F. Møllers Allé 3, DK-8000 Aarhus C., Denmark.
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20
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Thinh PV, Phuong NT, Brauner CJ, Huong DTT, Wood AT, Kwan GT, Conner JL, Bayley M, Wang T. Acid-base regulation in the air-breathing swamp eel (Monopterus albus) at different temperatures. J Exp Biol 2018; 221:jeb.172551. [DOI: 10.1242/jeb.172551] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2017] [Accepted: 02/12/2018] [Indexed: 11/20/2022]
Abstract
Vertebrates reduce arterial blood pH (pHa) when body temperature increases. In water-breathers this response occurs primarily by reducing plasma HCO3− levels with small changes in the partial pressure of CO2 (PCO2). In contrast, air-breathers mediate the decrease in pHa by increasing arterial PCO2 (PaCO2) at constant plasma HCO3− by reducing lung ventilation relative to metabolic CO2 production. Much less is known in bimodal breathers that utilize both water and air. Here, we characterize the influence of temperature on arterial acid-base balance and intracellular pH (pHi) in the bimodal breathing swamp eel, Monopterus albus. This teleost uses the buccopharyngeal cavity for gas exchange and has very reduced gills. When exposed to ecologically relevant temperatures (20, 25, 30 and 35°C) for 24 and 48h, pHa decreased by -0.025 pH units/°C (U/°C) in association with an increased PaCO2, but without changes in plasma [HCO3−]. Intracellular pH (pHi) was also reduced with increased temperature. The slope of pHi of liver and muscle was -0.014 and -0.019 U/°C, while the heart muscle showed a smaller reduction (-0.008U/°C). When exposed to hypercapnia (7 or 14 mmHg) at either 25 or 35°C, Monopterus albus elevated plasma [HCO3−] and therefore seemed to defend the new pHa set-point, demonstrating an adjusted control of acid-base balance with temperature. Overall, the effects of temperature on acid-base balance in Monopterus albus resemble air-breathing amniotes, and we discuss the possibility that this pattern of acid-base balance results from a progressive transition in CO2 excretion from water to air as temperature rises.
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Affiliation(s)
- Phan Vinh Thinh
- College of Aquaculture and Fisheries, Can Tho University, Can Tho City, Vietnam
| | - Nguyen Thanh Phuong
- College of Aquaculture and Fisheries, Can Tho University, Can Tho City, Vietnam
| | - Colin J. Brauner
- Department of Zoology, University of British Columbia, 6270 University Blvd.,Vancouver, BC, V6T 1Z4, Canada
| | - Do Thi Thanh Huong
- College of Aquaculture and Fisheries, Can Tho University, Can Tho City, Vietnam
| | | | - Garfield T. Kwan
- Scripps Institution of Oceanography, University of California San Diego, USA
| | | | - Mark Bayley
- Zoophysiology, Department of Bioscience, Aarhus University, Aarhus, Denmark
| | - Tobias Wang
- Zoophysiology, Department of Bioscience, Aarhus University, Aarhus, Denmark
- Aarhus Institute of Advanced Studies, 8000 Aarhus C, Denmark
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21
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Damsgaard C, Thomsen MT, Bayley M, Wang T. Air-breathing changes the pattern for temperature-induced pH regulation in a bimodal breathing teleost. J Comp Physiol B 2017; 188:451-459. [DOI: 10.1007/s00360-017-1134-1] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2017] [Revised: 10/22/2017] [Accepted: 10/25/2017] [Indexed: 11/28/2022]
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22
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Shartau RB, Baker DW, Crossley DA, Brauner CJ. Preferential intracellular pH regulation: hypotheses and perspectives. ACTA ACUST UNITED AC 2017; 219:2235-44. [PMID: 27489212 DOI: 10.1242/jeb.126631] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
The regulation of vertebrate acid-base balance during acute episodes of elevated internal PCO2 is typically characterized by extracellular pH (pHe) regulation. Changes in pHe are associated with qualitatively similar changes in intracellular tissue pH (pHi) as the two are typically coupled, referred to as 'coupled pH regulation'. However, not all vertebrates rely on coupled pH regulation; instead, some preferentially regulate pHi against severe and maintained reductions in pHe Preferential pHi regulation has been identified in several adult fish species and an aquatic amphibian, but never in adult amniotes. Recently, common snapping turtles were observed to preferentially regulate pHi during development; the pattern of acid-base regulation in these species shifts from preferential pHi regulation in embryos to coupled pH regulation in adults. In this Commentary, we discuss the hypothesis that preferential pHi regulation may be a general strategy employed by vertebrate embryos in order to maintain acid-base homeostasis during severe acute acid-base disturbances. In adult vertebrates, the retention or loss of preferential pHi regulation may depend on selection pressures associated with the environment inhabited and/or the severity of acid-base regulatory challenges to which they are exposed. We also consider the idea that the retention of preferential pHi regulation into adulthood may have been a key event in vertebrate evolution, with implications for the invasion of freshwater habitats, the evolution of air breathing and the transition of vertebrates from water to land.
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Affiliation(s)
- Ryan B Shartau
- Department of Zoology, University of British Columbia, Vancouver, British Columbia, Canada, V6T 1Z4
| | - Daniel W Baker
- Department of Fisheries and Aquaculture, Vancouver Island University, Nanaimo, British Columbia, Canada, V9R 5S5
| | - Dane A Crossley
- Department of Biological Sciences, University of North Texas, Denton, TX 76203-5017, USA
| | - Colin J Brauner
- Department of Zoology, University of British Columbia, Vancouver, British Columbia, Canada, V6T 1Z4
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23
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Wright PA, Turko AJ. Amphibious fishes: evolution and phenotypic plasticity. ACTA ACUST UNITED AC 2017; 219:2245-59. [PMID: 27489213 DOI: 10.1242/jeb.126649] [Citation(s) in RCA: 58] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2016] [Accepted: 06/29/2016] [Indexed: 12/25/2022]
Abstract
Amphibious fishes spend part of their life in terrestrial habitats. The ability to tolerate life on land has evolved independently many times, with more than 200 extant species of amphibious fishes spanning 17 orders now reported. Many adaptations for life out of water have been described in the literature, and adaptive phenotypic plasticity may play an equally important role in promoting favourable matches between the terrestrial habitat and behavioural, physiological, biochemical and morphological characteristics. Amphibious fishes living at the interface of two very different environments must respond to issues relating to buoyancy/gravity, hydration/desiccation, low/high O2 availability, low/high CO2 accumulation and high/low NH3 solubility each time they traverse the air-water interface. Here, we review the literature for examples of plastic traits associated with the response to each of these challenges. Because there is evidence that phenotypic plasticity can facilitate the evolution of fixed traits in general, we summarize the types of investigations needed to more fully determine whether plasticity in extant amphibious fishes can provide indications of the strategies used during the evolution of terrestriality in tetrapods.
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Affiliation(s)
- Patricia A Wright
- Department of Integrative Biology, University of Guelph, Guelph, Ontario, Canada N1G 2W1
| | - Andy J Turko
- Department of Integrative Biology, University of Guelph, Guelph, Ontario, Canada N1G 2W1
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24
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Gam LTH, Jensen FB, Damsgaard C, Huong DTT, Phuong NT, Bayley M. Extreme nitrite tolerance in the clown knifefish Chitala ornata is linked to up-regulation of methaemoglobin reductase activity. AQUATIC TOXICOLOGY (AMSTERDAM, NETHERLANDS) 2017; 187:9-17. [PMID: 28351760 DOI: 10.1016/j.aquatox.2017.03.013] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/24/2017] [Revised: 03/09/2017] [Accepted: 03/15/2017] [Indexed: 06/06/2023]
Abstract
The clown knifefish is a facultative air breather, which is widely farmed in freshwater ponds in Vietnam. Here we report a very high nitrite tolerance (96h LC50 of 7.82mM) in this species and examine the effects of 1mM (LC5) and 2.5mM (LC10) ambient nitrite on haemoglobin (Hb) derivatives, electrolyte levels, acid-base status, and total body water content during 7days of exposure. Furthermore, we tested the hypothesis that erythrocyte methaemoglobin (metHb) reductase activity is upregulated by nitrite exposure. Plasma nitrite levels increased for 2-3days but stayed below environmental levels and fell towards control values during the last half of the exposure period. Plasma nitrate, in contrast, rose continuously, reflecting detoxification of nitrite to nitrate. MetHb generated from the reaction between nitrite and erythrocyte Hb reached 38% at day 2, but then decreased to 17% by the end of experiment. The first order rate constant for metHb reduction by erythrocyte metHb reductase increased from 0.01 in controls to 0.046min-1 after 6days of nitrite exposure, showing up-regulation of this enzyme. While such upregulation has been suggested in nitrite-exposed fish species, this study provides the first experimental evidence.
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Affiliation(s)
- Le Thi Hong Gam
- College of Aquaculture and Fisheries, Can Tho Uiniversity, Can Tho City, Viet Nam
| | - Frank Bo Jensen
- Department of Biology, University of Southern Denmark, Odense, Denmark
| | | | - Do Thi Thanh Huong
- College of Aquaculture and Fisheries, Can Tho Uiniversity, Can Tho City, Viet Nam
| | - Nguyen Thanh Phuong
- College of Aquaculture and Fisheries, Can Tho Uiniversity, Can Tho City, Viet Nam
| | - Mark Bayley
- Zoophysiology, Department of Bioscience, Aarhus University, Aarhus, Denmark.
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25
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White sturgeon (Acipenser transmontanus) acid-base regulation differs in response to different types of acidoses. J Comp Physiol B 2017; 187:985-994. [PMID: 28283796 DOI: 10.1007/s00360-017-1065-x] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2016] [Revised: 02/02/2017] [Accepted: 02/09/2017] [Indexed: 10/20/2022]
Abstract
White sturgeon (Acipenser transmontanus) completely protect intracellular tissue pH (pHi) despite large reductions in extracellular (blood) pH (pHe), termed preferential pHi regulation, in response to elevated environmental PCO2 (hypercarbia) and in general appear to be relatively resilient to stressors. Preferential pHi regulation is thought to be associated with hypercarbia tolerance in general, but has also recently been observed to protect pHi against metabolic acidoses induced by exhaustive exercise and anoxia in a tropical air breathing catfish. We hypothesized that preferential pHi regulation may also be a general strategy of acid-base regulation in sturgeon. To address this hypothesis, severe acidoses were imposed to reduce pHe, and the presence or absence of preferential pHi regulation was assessed in red blood cells (RBC), heart, brain, liver and white muscle. A respiratory acidosis was imposed using hyperoxia, while metabolic acidoses were induced by exhaustive exercise, anoxia or air exposure. Reductions in pHe occurred following hyperoxia (0.15 units), exhaustive exercise (0.30 units), anoxia (0.10 units) and air exposure (0.35 units); all acidoses reduced RBC pHi. Following hyperoxia, heart, brain and liver pHi were preferentially regulated against the reduction in pHe, similar to hypercarbia exposure. Following all metabolic acidoses heart pHi was protected and brain pHi remained unchanged following exhaustive exercise and air exposure, however, brain pHi was reduced following anoxia. Liver and white muscle pHi were reduced following all metabolic acidoses. These results suggest preferential pHi regulation may be a general strategy during respiratory acidoses but during metabolic acidoses, the response differs between source of acidoses and tissues.
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26
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Gill remodelling and growth rate of striped catfish Pangasianodon hypophthalmus under impacts of hypoxia and temperature. Comp Biochem Physiol A Mol Integr Physiol 2016; 203:288-296. [PMID: 27768904 DOI: 10.1016/j.cbpa.2016.10.006] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2016] [Revised: 10/11/2016] [Accepted: 10/14/2016] [Indexed: 01/01/2023]
Abstract
Gill morphometric and gill plasticity of the air-breathing striped catfish (Pangasianodon hypophthalmus) exposed to different temperatures (present day 27°C and future 33°C) and different air saturation levels (92% and 35%) during 6weeks were investigated using vertical sections to estimate the respiratory lamellae surface areas, harmonic mean barrier thicknesses, and gill component volumes. Gill respiratory surface area (SA) and harmonic mean water - blood barrier thicknesses (HM) of the fish were strongly affected by both environmental temperature and oxygen level. Thus initial values for 27°C normoxic fish (12.4±0.8g) were 211.8±21.6mm2g-1 and 1.67±0.12μm for SA and HM respectively. After 5weeks in same conditions or in the combinations of 33°C and/or PO2 of 55mmHg, this initial surface area scaled allometrically with size for the 33°C hypoxic group, whereas branchial SA was almost eliminated in the 27°C normoxic group, with other groups intermediate. In addition, elevated temperature had an astounding effect on growth with the 33°C group growing nearly 8-fold faster than the 27°C fish.
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27
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Zhang D, Liu S, Zhang J, Zhang JK, Hu C, Liu Y. In vivo effects of Aphanizomenon flos-aquae DC-1 aphantoxins on gas exchange and ion equilibrium in the zebrafish gill. AQUATIC TOXICOLOGY (AMSTERDAM, NETHERLANDS) 2016; 177:484-493. [PMID: 27424100 DOI: 10.1016/j.aquatox.2016.06.024] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/19/2016] [Revised: 06/27/2016] [Accepted: 06/28/2016] [Indexed: 06/06/2023]
Abstract
Aphantoxins, neurotoxins or paralytic shellfish poisons (PSPs) generated by Aphanizomenon flos-aquae, are a threat to environmental safety and human health in eutrophic waters worldwide. The molecular mechanisms of neurotoxin function have been studied; however, the effects of these neurotoxins on oxidative stress, ion transport, gas exchange, and branchial ultrastructure in fish gills are not fully understood. Aphantoxins extracted from A. flos-aquae DC-1 were detected by high-performance liquid chromatography. The major ingredients were gonyautoxins 1 and 5 and neosaxitoxin, which comprised 34.04%, 21.28%, and 12.77% of the total, respectively. Zebrafish (Danio rerio) were administered A. flos-aquae DC-1 aphantoxins at 5.3 or 7.61μg saxitoxin equivalents (eq)/kg (low and high doses, respectively) by intraperitoneal injection. The activities of Na(+)-K(+)-ATPase (NKA), carbonic anhydrase (CA), and lactate dehydrogenase (LDH), ultrastructural alterations in chloride and epithelial cells, and reactive oxygen species (ROS) and total antioxidative capacity (T-AOC) were investigated in the gills during the first 24h after exposure. Aphantoxins significantly increased the level of ROS and decreased the T-AOC in zebrafish gills from 3 to 12h post-exposure, suggesting an induction of oxidative stress and inhibition of antioxidant capacity. Reduced activities of NKA and CA demonstrated abnormal ion transport and gas exchange in the gills of aphantoxin-treated fish. Toxin administration also resulted in increased LDH activity and ultrastructural alterations in chloride and epithelial cells, suggesting a disruption of function and structure in zebrafish gills. The observed abnormalities in zebrafish gills occurred in a time- and dose-dependent manner. These findings demonstrate that aphantoxins or PSPs may inhibit ion transport and gas exchange, increase LDH activity, and result in ultrastructural damage to the gills through elevations in oxidative stress and reduced antioxidant capacity. These effects of aphantoxins in the gills of zebrafish suggest an induction of respiratory toxicity. The parameters investigated in this study may be also considered as biomarkers for studying aphantoxin/PSP exposure and cyanobacterial blooms in nature.
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Affiliation(s)
- Delu Zhang
- Department of Lifescience and Biotechnology, College of Chemistry, Chemical Engineering and Life Sciences, Wuhan University of Technology, Wuhan 430070, PR China.
| | - Siyi Liu
- Department of Lifescience and Biotechnology, College of Chemistry, Chemical Engineering and Life Sciences, Wuhan University of Technology, Wuhan 430070, PR China
| | - Jing Zhang
- College of Chemistry and Molecular Sciences, Wuhan University, Wuhan 430072, PR China
| | - Jian Kong Zhang
- Department of Lifescience and Biotechnology, College of Chemistry, Chemical Engineering and Life Sciences, Wuhan University of Technology, Wuhan 430070, PR China
| | - Chunxiang Hu
- Key Laboratory of Algal Biology, Institute of Hydrobiology, The Chinese Academy of Sciences, Wuhan 430072, PR China.
| | - Yongding Liu
- Key Laboratory of Algal Biology, Institute of Hydrobiology, The Chinese Academy of Sciences, Wuhan 430072, PR China
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Burggren WW, Bautista GM, Coop SC, Couturier GM, Delgadillo SP, García RM, González CAA. Developmental cardiorespiratory physiology of the air-breathing tropical gar, Atractosteus tropicus. Am J Physiol Regul Integr Comp Physiol 2016; 311:R689-R701. [PMID: 27465731 DOI: 10.1152/ajpregu.00022.2016] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2016] [Accepted: 07/08/2016] [Indexed: 12/18/2022]
Abstract
The physiological transition to aerial breathing in larval air-breathing fishes is poorly understood. We investigated gill ventilation frequency (fG), heart rate (fH), and air breathing frequency (fAB) as a function of development, activity, hypoxia, and temperature in embryos/larvae from day (D) 2.5 to D30 posthatch of the tropical gar, Atractosteus tropicus, an obligate air breather. Gill ventilation at 28°C began at approximately D2, peaking at ∼75 beats/min on D5, before declining to ∼55 beats/min at D30. Heart beat began ∼36-48 h postfertilization and ∼1 day before hatching. fH peaked between D3 and D10 at ∼140 beats/min, remaining at this level through D30. Air breathing started very early at D2.5 to D3.5 at 1-2 breaths/h, increasing to ∼30 breaths/h at D15 and D30. Forced activity at all stages resulted in a rapid but brief increase in both fG and fH, (but not fAB), indicating that even in these early larval stages, reflex control existed over both ventilation and circulation prior to its increasing importance in older fishes. Acute progressive hypoxia increased fG in D2.5-D10 larvae, but decreased fG in older larvae (≥D15), possibly to prevent branchial O2 loss into surrounding water. Temperature sensitivity of fG and fH measured at 20°C, 25°C, 28°C and 38°C was largely independent of development, with a Q10 between 20°C and 38°C of ∼2.4 and ∼1.5 for fG and fH, respectively. The rapid onset of air breathing, coupled with both respiratory and cardiovascular reflexes as early as D2.5, indicates that larval A. tropicus develops "in the fast lane."
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Affiliation(s)
- Warren W Burggren
- Developmental Integrative Biology Group, Department of Biology, University of North Texas, Denton, Texas; and
| | - Gil Martinez Bautista
- Laboratorio de Acuicultura Tropical, División Académica de Ciencias Biológicas, Universidad Juárez Autónoma de Tabasco, Villahermosa, Tabasco, Mexico
| | - Susana Camarillo Coop
- Laboratorio de Acuicultura Tropical, División Académica de Ciencias Biológicas, Universidad Juárez Autónoma de Tabasco, Villahermosa, Tabasco, Mexico
| | - Gabriel Márquez Couturier
- Laboratorio de Acuicultura Tropical, División Académica de Ciencias Biológicas, Universidad Juárez Autónoma de Tabasco, Villahermosa, Tabasco, Mexico
| | - Salomón Páramo Delgadillo
- Laboratorio de Acuicultura Tropical, División Académica de Ciencias Biológicas, Universidad Juárez Autónoma de Tabasco, Villahermosa, Tabasco, Mexico
| | - Rafael Martínez García
- Laboratorio de Acuicultura Tropical, División Académica de Ciencias Biológicas, Universidad Juárez Autónoma de Tabasco, Villahermosa, Tabasco, Mexico
| | - Carlos Alfonso Alvarez González
- Laboratorio de Acuicultura Tropical, División Académica de Ciencias Biológicas, Universidad Juárez Autónoma de Tabasco, Villahermosa, Tabasco, Mexico
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29
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Air breathing and aquatic gas exchange during hypoxia in armoured catfish. J Comp Physiol B 2016; 187:117-133. [DOI: 10.1007/s00360-016-1024-y] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2016] [Revised: 06/23/2016] [Accepted: 07/19/2016] [Indexed: 10/21/2022]
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Jiang Y, Feng S, Xu J, Zhang S, Li S, Sun X, Xu P. Comparative transcriptome analysis between aquatic and aerial breathing organs of Channa argus to reveal the genetic basis underlying bimodal respiration. Mar Genomics 2016; 29:89-96. [PMID: 27318671 DOI: 10.1016/j.margen.2016.06.002] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2016] [Revised: 05/26/2016] [Accepted: 06/10/2016] [Indexed: 10/21/2022]
Abstract
Aerial breathing in fish was an important adaption for successful survival in hypoxic water. All aerial breathing fish are bimodal breathers. It is intriguing that they can obtain oxygen from both air and water. However, the genetic basis underlying bimodal breathing has not been extensively studied. In this study, we performed next-generation sequencing on a bimodal breathing fish, the Northern snakehead, Channa argus, and generated a transcriptome profiling of C. argus. A total of 53,591 microsatellites and 26,378 SNPs were identified and classified. A Ka/Ks analysis of the unigenes indicated that 63 genes were under strong positive selection. Furthermore, the transcriptomes from the aquatic breathing organ (gill) and the aerial breathing organ (suprabranchial chamber) were sequenced and compared, and the results showed 1,966 genes up-regulated in the gill and 2,727 genes up-regulated in the suprabranchial chamber. A gene pathway analysis concluded that four functional categories were significant, of which angiogenesis and elastic fibre formation were up-regulated in the suprabranchial chamber, indicating that the aerial breathing organ may be more efficient for gas exchange due to its highly vascularized and elastic structure. In contrast, ion uptake and transport and acid-base balance were up-regulated in the gill, indicating that the aquatic breathing organ functions in ion homeostasis and acid-base balance, in addition to breathing. Understanding the genetic mechanism underlying bimodal breathing will shed light on the initiation and importance of aerial breathing in the evolution of vertebrates.
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Affiliation(s)
- Yanliang Jiang
- CAFS Key Laboratory of Aquatic Genomics, Beijing Key Laboratory of Fishery Biotechnology, Centre for Applied Aquatic Genomics, Chinese Academy of Fishery Sciences, Beijing 100141, China
| | - Shuaisheng Feng
- CAFS Key Laboratory of Aquatic Genomics, Beijing Key Laboratory of Fishery Biotechnology, Centre for Applied Aquatic Genomics, Chinese Academy of Fishery Sciences, Beijing 100141, China; College of Life Sciences, Shanghai Ocean University, Shanghai 201306, China
| | - Jian Xu
- CAFS Key Laboratory of Aquatic Genomics, Beijing Key Laboratory of Fishery Biotechnology, Centre for Applied Aquatic Genomics, Chinese Academy of Fishery Sciences, Beijing 100141, China
| | - Songhao Zhang
- CAFS Key Laboratory of Aquatic Genomics, Beijing Key Laboratory of Fishery Biotechnology, Centre for Applied Aquatic Genomics, Chinese Academy of Fishery Sciences, Beijing 100141, China
| | - Shangqi Li
- CAFS Key Laboratory of Aquatic Genomics, Beijing Key Laboratory of Fishery Biotechnology, Centre for Applied Aquatic Genomics, Chinese Academy of Fishery Sciences, Beijing 100141, China
| | - Xiaoqing Sun
- CAFS Key Laboratory of Aquatic Genomics, Beijing Key Laboratory of Fishery Biotechnology, Centre for Applied Aquatic Genomics, Chinese Academy of Fishery Sciences, Beijing 100141, China
| | - Peng Xu
- CAFS Key Laboratory of Aquatic Genomics, Beijing Key Laboratory of Fishery Biotechnology, Centre for Applied Aquatic Genomics, Chinese Academy of Fishery Sciences, Beijing 100141, China.
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Rimoldi S, Terova G, Zaccone G, Parker T, Kuciel M, Dabrowski K. The Effect of Hypoxia and Hyperoxia on Growth and Expression of Hypoxia-Related Genes and Proteins in Spotted Gar Lepisosteus oculatus Larvae and Juveniles. JOURNAL OF EXPERIMENTAL ZOOLOGY PART B-MOLECULAR AND DEVELOPMENTAL EVOLUTION 2016; 326:250-67. [PMID: 27245617 DOI: 10.1002/jez.b.22680] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/19/2016] [Revised: 04/15/2016] [Accepted: 05/09/2016] [Indexed: 01/23/2023]
Abstract
We studied the molecular responses to different water oxygen levels in gills and swim bladder of spotted gar (Lepisosteus oculatus), a bimodal breather. Fish at swim-up stage were exposed for 71 days to normoxic, hypoxic, and hyperoxic water conditions. Then, all aquaria were switched to normoxic conditions for recovery until the end of the experiment (120 days). Fish were sampled at the beginning of the experiment, and then at 71 days of exposure and at 8 days of recovery. We first cloned three hypoxia-related genes, hypoxia-inducible factor 2α (HIF-2α), Na(+) /H(+) exchanger 1 (NHE-1), and NHE-3, and uploaded their cDNA sequences in the GeneBank database. We then used One Step Taqman® real-time PCR to quantify the mRNA copies of target genes in gills and swim bladder of fish exposed to different water O2 levels. We also determined the protein expression of HIF-2α and neuronal nitric oxide synthase (nNOS) in the swim bladder by using confocal immunofluorescence. Hypoxic stress for 71 days significantly increased the mRNA copies of HIF-2α and NHE-1 in gills and swim bladder, whereas normoxic recovery for 8 days decreased the HIF-2α mRNA copies to control values in both tissues. We did not found significant changes in mRNA copies of the NHE-3 gene in either gills or swim bladder in response to hypoxia and hyperoxia. Unlike in normoxic swim bladder, double immunohistochemical staining in hypoxic and hyperoxic swim bladder using nNOS/HIF-2α showed extensive bundles of HIF-2α-positive nerve fibers in the trabecular musculature associated with a few varicose nNOS immunoreactive nerve terminals.
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Affiliation(s)
- Simona Rimoldi
- Department of Biotechnology and Life Sciences, University of Insubria, Varese, Italy
| | - Genciana Terova
- Department of Biotechnology and Life Sciences, University of Insubria, Varese, Italy.,Inter-University Centre for Research in Protein Biotechnologies, "The Protein Factory", Polytechnic University of Milan and University of Insubria, Varese, Italy
| | - Giacomo Zaccone
- Department of Biomedical and Dental Sciences and Morphofunctional Imaging, University of Messina, Messina, Italy
| | - Tim Parker
- School of Environment and Natural Resources, Ohio State University, Columbus, Ohio
| | - Michal Kuciel
- Poison Information Centre, Jagiellonian University Medical College, Crakow, Poland
| | - Konrad Dabrowski
- School of Environment and Natural Resources, Ohio State University, Columbus, Ohio
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32
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Shartau RB, Crossley DA, Kohl ZF, Brauner CJ. Embryonic common snapping turtles (Chelydra serpentina) preferentially regulate intracellular tissue pH during acid-base challenges. J Exp Biol 2016; 219:1994-2002. [DOI: 10.1242/jeb.136119] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2015] [Accepted: 04/14/2016] [Indexed: 11/20/2022]
Abstract
The nests of embryonic turtles naturally experience elevated CO2 (hypercarbia), which leads to increased blood PCO2 and a respiratory acidosis resulting in reduced blood pH [extracellular pH (pHe)]. Some fishes preferentially regulate tissue pH [intracellular pH (pHi)] against changes in pHe; this has been proposed to be associated with exceptional CO2 tolerance and has never been identified in amniotes. As embryonic turtles may be CO2 tolerant based on nesting strategy, we hypothesized that they preferentially regulate pHi, conferring tolerance to severe acute acid-base challenges. This hypothesis was tested by investigating pH regulation in common snapping turtles (Chelydra serpentina) reared in normoxia then exposed to hypercarbia (13kPa PCO2) for 1h at three developmental ages, 70 and 90% of incubation, and in yearlings. Hypercarbia reduced pHe but not pHi, at all developmental ages. At 70% of incubation, pHe was depressed by 0.324 pH units while pHi of brain, white muscle, and lung increased; heart, liver, and kidney pHi remained unchanged. At 90% of incubation, pHe was depressed by 0.352 pH units but heart pHi increased with no change in pHi of other tissues. Yearling exhibited a pHe reduction of 0.235 pH units but had no changes in pHi of any tissues. The results indicate common snapping turtles preferentially regulate pHi during development, but the degree of the response is reduced throughout development. This is the first time preferential pHi regulation has been identified in an amniote. These findings may provide insight into the evolution of acid-base homeostasis during development of amniotes, and vertebrates in general.
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Affiliation(s)
- Ryan B. Shartau
- Department of Zoology, University of British Columbia, Vancouver, British Columbia, Canada
| | - Dane A. Crossley
- Department of Biological Sciences, University of North Texas, Denton, Texas, USA
| | - Zachary F. Kohl
- Department of Biological Sciences, University of North Texas, Denton, Texas, USA
| | - Colin J. Brauner
- Department of Zoology, University of British Columbia, Vancouver, British Columbia, Canada
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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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34
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Turko AJ, Wright PA. Evolution, ecology and physiology of amphibious killifishes (Cyprinodontiformes). JOURNAL OF FISH BIOLOGY 2015; 87:815-835. [PMID: 26299792 DOI: 10.1111/jfb.12758] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/13/2013] [Accepted: 06/24/2015] [Indexed: 06/04/2023]
Abstract
The order Cyprinodontiformes contains an exceptional diversity of amphibious taxa, including at least 34 species from six families. These cyprinodontiforms often inhabit intertidal or ephemeral habitats characterized by low dissolved oxygen or otherwise poor water quality, conditions that have been hypothesized to drive the evolution of terrestriality. Most of the amphibious species are found in the Rivulidae, Nothobranchiidae and Fundulidae. It is currently unclear whether the pattern of amphibiousness observed in the Cyprinodontiformes is the result of repeated, independent evolutions, or stems from an amphibious common ancestor. Amphibious cyprinodontiforms leave water for a variety of reasons: some species emerse only briefly, to escape predation or capture prey, while others occupy ephemeral habitats by living for months at a time out of water. Fishes able to tolerate months of emersion must maintain respiratory gas exchange, nitrogen excretion and water and salt balance, but to date knowledge of the mechanisms that facilitate homeostasis on land is largely restricted to model species. This review synthesizes the available literature describing amphibious lifestyles in cyprinodontiforms, compares the behavioural and physiological strategies used to exploit the terrestrial environment and suggests directions and ideas for future research.
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Affiliation(s)
- A J Turko
- Department of Integrative Biology, University of Guelph, 488 Gordon Street, Guelph, ON, N1G 2W1, Canada
| | - P A Wright
- Department of Integrative Biology, University of Guelph, 488 Gordon Street, Guelph, ON, N1G 2W1, Canada
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35
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Damsgaard C, Gam LTH, Dang DT, Van Thinh P, Huong DTT, Wang T, Bayley M. High capacity for extracellular acid-base regulation in the air-breathing fish Pangasianodon hypophthalmus. J Exp Biol 2015; 218:1290-4. [DOI: 10.1242/jeb.117671] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2014] [Accepted: 03/09/2015] [Indexed: 02/03/2023]
Abstract
The evolution of accessory air-breathing structures is typically associated with reduction of the gills, although branchial ion transport remains pivotal for acid-base and ion-regulation. Therefore, air-breathing fishes are believed to have a low capacity for extracellular pH regulation during a respiratory acidosis. In the present study, we investigated acid-base regulation during hypercapnia in the air-breathing fish Pangasianodon hypophthalmus in normoxic and hypoxic water at 28-30°C. Contrary to previous studies, we show that this air-breathing fish has a pronounced ability to regulate pHe during hypercapnia, with complete metabolic compensation of extracellular pH within 72 h of exposure to hypoxic hypercapnia with CO2 levels above 34 mmHg. The high capacity for pHe regulation relies on a pronounced ability to increase [HCO3−]plasma. Our study illustrates the diversity in the physiology of air-breathing fishes, such that generalizations across phylogenies may be difficult.
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Affiliation(s)
| | - Le Thi Hong Gam
- College of Aquaculture and Fisheries, Can Tho University, Can Tho City, Vietnam
| | - Diem Tuong Dang
- College of Aquaculture and Fisheries, Can Tho University, Can Tho City, Vietnam
| | - Phan Van Thinh
- College of Aquaculture and Fisheries, Can Tho University, Can Tho City, Vietnam
| | - Do Thi Thanh Huong
- College of Aquaculture and Fisheries, Can Tho University, Can Tho City, Vietnam
| | - Tobias Wang
- Zoophysiology, Institute for Bioscience, Aarhus University, Aarhus, Denmark
| | - Mark Bayley
- Zoophysiology, Institute for Bioscience, Aarhus University, Aarhus, Denmark
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36
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Lefevre S, Damsgaard C, Pascale DR, Nilsson GE, Stecyk JAW. Air breathing in the Arctic: influence of temperature, hypoxia, activity and restricted air access on respiratory physiology of the Alaska blackfish Dallia pectoralis. J Exp Biol 2014; 217:4387-98. [PMID: 25394628 PMCID: PMC4375840 DOI: 10.1242/jeb.105023] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2014] [Accepted: 10/28/2014] [Indexed: 01/21/2023]
Abstract
The Alaska blackfish (Dallia pectoralis) is an air-breathing fish native to Alaska and the Bering Sea islands, where it inhabits lakes that are ice-covered in the winter, but enters warm and hypoxic waters in the summer to forage and reproduce. To understand the respiratory physiology of this species under these conditions and the selective pressures that maintain the ability to breathe air, we acclimated fish to 5°C and 15°C and used respirometry to measure: standard oxygen uptake (Ṁ(O₂)) in normoxia (19.8 kPa P(O₂)) and hypoxia (2.5 kPa), with and without access to air; partitioning of standard Ṁ(O₂) in normoxia and hypoxia; maximum Ṁ(O₂) and partitioning after exercise; and critical oxygen tension (P(crit)). Additionally, the effects of temperature acclimation on haematocrit, haemoglobin oxygen affinity and gill morphology were assessed. Standard Ṁ(O₂) was higher, but air breathing was not increased, at 15°C or after exercise at both temperatures. Fish acclimated to 5°C or 15°C increased air breathing to compensate and fully maintain standard Ṁ(O₂) in hypoxia. Fish were able to maintain Ṁ(O₂) through aquatic respiration when air was denied in normoxia, but when air was denied in hypoxia, standard Ṁ(O₂) was reduced by ∼30-50%. P(crit) was relatively high (5 kPa) and there were no differences in P(crit), gill morphology, haematocrit or haemoglobin oxygen affinity at the two temperatures. Therefore, Alaska blackfish depends on air breathing in hypoxia and additional mechanisms must thus be utilised to survive hypoxic submergence during the winter, such as hypoxia-induced enhancement in the capacities for carrying and binding blood oxygen, behavioural avoidance of hypoxia and suppression of metabolic rate.
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Affiliation(s)
- Sjannie Lefevre
- Department of Biosciences, University of Oslo, Oslo 0316, Norway.
| | | | - Desirae R Pascale
- Department of Biological Sciences, University of Alaska Anchorage, AK 99508, USA
| | - Göran E Nilsson
- Department of Biosciences, University of Oslo, Oslo 0316, Norway
| | - Jonathan A W Stecyk
- Department of Biological Sciences, University of Alaska Anchorage, AK 99508, USA
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37
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High blood oxygen affinity in the air-breathing swamp eel Monopterus albus. Comp Biochem Physiol A Mol Integr Physiol 2014; 178:102-8. [DOI: 10.1016/j.cbpa.2014.08.001] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2014] [Revised: 08/04/2014] [Accepted: 08/12/2014] [Indexed: 11/24/2022]
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Turko AJ, Robertson CE, Bianchini K, Freeman M, Wright PA. The amphibious fish Kryptolebias marmoratus uses different strategies to maintain oxygen delivery during aquatic hypoxia and air exposure. ACTA ACUST UNITED AC 2014; 217:3988-95. [PMID: 25267849 DOI: 10.1242/jeb.110601] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Despite the abundance of oxygen in atmospheric air relative to water, the initial loss of respiratory surface area and accumulation of carbon dioxide in the blood of amphibious fishes during emersion may result in hypoxemia. Given that the ability to respond to low oxygen conditions predates the vertebrate invasion of land, we hypothesized that amphibious fishes maintain O2 uptake and transport while emersed by mounting a co-opted hypoxia response. We acclimated the amphibious fish Kryptolebias marmoratus, which are able to remain active for weeks in both air and water, for 7 days to normoxic brackish water (15‰, ~21kPa O2; control), aquatic hypoxia (~3.6kPa), normoxic air (~21 kPa) or aerial hypoxia (~13.6kPa). Angiogenesis in the skin and bucco-opercular chamber was pronounced in air- versus water-acclimated fish, but not in response to hypoxia. Aquatic hypoxia increased the O2-carrying capacity of blood via a large (40%) increase in red blood cell density and a small increase in the affinity of hemoglobin for O2 (P50 decreased 11%). In contrast, air exposure increased the hemoglobin O2 affinity (decreased P50) by 25% without affecting the number of red blood cells. Acclimation to aerial hypoxia both increased the O2-carrying capacity and decreased the hemoglobin O2 affinity. These results suggest that O2 transport is regulated both by O2 availability and also, independently, by air exposure. The ability of the hematological system to respond to air exposure independent of O2 availability may allow extant amphibious fishes, and may also have allowed primitive tetrapods to cope with the complex challenges of aerial respiration during the invasion of land.
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Affiliation(s)
- Andy J Turko
- Department of Integrative Biology, University of Guelph, Guelph, ON N1G 2W1, Canada
| | - Cayleih E Robertson
- Department of Integrative Biology, University of Guelph, Guelph, ON N1G 2W1, Canada
| | - Kristin Bianchini
- Department of Integrative Biology, University of Guelph, Guelph, ON N1G 2W1, Canada
| | - Megan Freeman
- Department of Integrative Biology, University of Guelph, Guelph, ON N1G 2W1, Canada
| | - Patricia A Wright
- Department of Integrative Biology, University of Guelph, Guelph, ON N1G 2W1, Canada
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Preferential intracellular pH regulation represents a general pattern of pH homeostasis during acid-base disturbances in the armoured catfish, Pterygoplichthys pardalis. J Comp Physiol B 2014; 184:709-18. [PMID: 24973965 DOI: 10.1007/s00360-014-0838-8] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2014] [Revised: 04/04/2014] [Accepted: 06/05/2014] [Indexed: 01/03/2023]
Abstract
Preferential intracellular pH (pHi) regulation, where pHi is tightly regulated in the face of a blood acidosis, has been observed in a few species of fish, but only during elevated blood PCO2. To determine whether preferential pHi regulation may represent a general pattern for acid-base regulation during other pH disturbances we challenged the armoured catfish, Pterygoplichthys pardalis, with anoxia and exhaustive exercise, to induce a metabolic acidosis, and bicarbonate injections to induce a metabolic alkalosis. Fish were terminally sampled 2-3 h following the respective treatments and extracellular blood pH, pHi of red blood cells (RBC), brain, heart, liver and white muscle, and plasma lactate and total CO2 were measured. All treatments resulted in significant changes in extracellular pH and RBC pHi that likely cover a large portion of the pH tolerance limits of this species (pH 7.15-7.86). In all tissues other than RBC, pHi remained tightly regulated and did not differ significantly from control values, with the exception of a decrease in white muscle pHi after anoxia and an increase in liver pHi following a metabolic alkalosis. Thus preferential pHi regulation appears to be a general pattern for acid-base homeostasis in the armoured catfish and may be a common response in Amazonian fishes.
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40
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Lefevre S, Bayley M, McKenzie DJ, Craig JF. Air-breathing fishes. JOURNAL OF FISH BIOLOGY 2014; 84:547-553. [PMID: 24588640 DOI: 10.1111/jfb.12349] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Affiliation(s)
- S Lefevre
- Department of Biosciences, University of Oslo, 0316, Oslo, Norway
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41
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Lefevre S, Wang T, Jensen A, Cong NV, Huong DTT, Phuong NT, Bayley M. Air-breathing fishes in aquaculture. What can we learn from physiology? JOURNAL OF FISH BIOLOGY 2014; 84:705-731. [PMID: 24498927 DOI: 10.1111/jfb.12302] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
During the past decade, the culture of air-breathing fish species has increased dramatically and is now a significant global source of protein for human consumption. This development has generated a need for specific information on how to maximize growth and minimize the environmental effect of culture systems. Here, the existing data on metabolism in air-breathing fishes are reviewed, with the aim of shedding new light on the oxygen requirements of air-breathing fishes in aquaculture, reaching the conclusion that aquatic oxygenation is much more important than previously assumed. In addition, the possible effects on growth of the recurrent exposure to deep hypoxia and associated elevated concentrations of carbon dioxide, ammonia and nitrite, that occurs in the culture ponds used for air-breathing fishes, are discussed. Where data on air-breathing fishes are simply lacking, data for a few water-breathing species will be reviewed, to put the physiological effects into a growth perspective. It is argued that an understanding of air-breathing fishes' respiratory physiology, including metabolic rate, partitioning of oxygen uptake from air and water in facultative air breathers, the critical oxygen tension, can provide important input for the optimization of culture practices. Given the growing importance of air breathers in aquaculture production, there is an urgent need for further data on these issues.
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Affiliation(s)
- S Lefevre
- Zoophysiology section, Department of Bioscience, C. F. Møllers Allé 3, 8000 Aarhus C, Denmark
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Lefevre S, Domenici P, McKenzie DJ. Swimming in air-breathing fishes. JOURNAL OF FISH BIOLOGY 2014; 84:661-681. [PMID: 24502687 DOI: 10.1111/jfb.12308] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/01/2013] [Accepted: 11/15/2013] [Indexed: 06/03/2023]
Abstract
Fishes with bimodal respiration differ in the extent of their reliance on air breathing to support aerobic metabolism, which is reflected in their lifestyles and ecologies. Many freshwater species undertake seasonal and reproductive migrations that presumably involve sustained aerobic exercise. In the six species studied to date, aerobic exercise in swim flumes stimulated air-breathing behaviour, and there is evidence that surfacing frequency and oxygen uptake from air show an exponential increase with increasing swimming speed. In some species, this was associated with an increase in the proportion of aerobic metabolism met by aerial respiration, while in others the proportion remained relatively constant. The ecological significance of anaerobic swimming activities, such as sprinting and fast-start manoeuvres during predator-prey interactions, has been little studied in air-breathing fishes. Some species practise air breathing during recovery itself, while others prefer to increase aquatic respiration, possibly to promote branchial ion exchange to restore acid-base balance, and to remain quiescent and avoid being visible to predators. Overall, the diversity of air-breathing fishes is reflected in their swimming physiology as well, and further research is needed to increase the understanding of the differences and the mechanisms through which air breathing is controlled and used during exercise.
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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
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