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Rees BB, Reemeyer JE, Binning SA, Brieske SD, Clark TD, De Bonville J, Eisenberg RM, Raby GD, Roche D, Rummer JL, Zhang Y. Estimating maximum oxygen uptake of fishes during swimming and following exhaustive chase - different results, biological bases and applications. J Exp Biol 2024; 227:jeb246439. [PMID: 38819376 DOI: 10.1242/jeb.246439] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/01/2024]
Abstract
The maximum rate at which animals take up oxygen from their environment (ṀO2,max) is a crucial aspect of their physiology and ecology. In fishes, ṀO2,max is commonly quantified by measuring oxygen uptake either during incremental swimming tests or during recovery from an exhaustive chase. In this Commentary, we compile recent studies that apply both techniques to the same fish and show that the two methods typically yield different mean estimates of ṀO2,max for a group of individuals. Furthermore, within a group of fish, estimates of ṀO2,max determined during swimming are poorly correlated with estimates determined during recovery from chasing (i.e. an individual's ṀO2,max is not repeatable across methods). One explanation for the lack of agreement is that these methods measure different physiological states, each with their own behavioural, anatomical and biochemical determinants. We propose that these methods are not directly interchangeable but, rather, each is suited to address different questions in fish biology. We suggest that researchers select the method that reflects the biological contexts of their study, and we advocate for the use of accurate terminology that acknowledges the technique used to elevate ṀO2 (e.g. peak ṀO2,swim or peak ṀO2,recovery). If the study's objective is to estimate the 'true' ṀO2,max of an individual or species, we recommend that pilot studies compare methods, preferably using repeated-measures designs. We hope that these recommendations contribute new insights into the causes and consequences of variation in ṀO2,max within and among fish species.
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Affiliation(s)
- Bernard B Rees
- Department of Biological Sciences, University of New Orleans, New Orleans, LA 70148, USA
| | | | - Sandra A Binning
- Département de Sciences Biologiques, Université de Montréal, Montréal, QC, CanadaH2V 0B3
| | - Samantha D Brieske
- Department of Biological Sciences, University of New Orleans, New Orleans, LA 70148, USA
| | - Timothy D Clark
- School of Life and Environmental Science, Deakin University, Geelong, Victoria, Australia3216
| | - Jeremy De Bonville
- Département de Sciences Biologiques, Université de Montréal, Montréal, QC, CanadaH2V 0B3
| | - Rachel M Eisenberg
- Department of Zoology, University of British Columbia, Vancouver, BC, CanadaV6T 1Z4
| | - Graham D Raby
- Department of Biology, Trent University, Peterborough, ON, CanadaK9L 0G2
| | - Dominique Roche
- Social Sciences and Humanities Research Council of Canada, Ottawa, ON, CanadaK1R 0E3
| | - Jodie L Rummer
- College of Science and Engineering, James Cook University, Townsville, QLD 4811, Australia
| | - Yangfan Zhang
- Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, MA 02138, USA
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2
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Harter TS, Damsgaard C, Regan MD. Linking environmental salinity to respiratory phenotypes and metabolic rate in fishes: a data mining and modelling approach. J Exp Biol 2022; 225:274262. [PMID: 35258603 DOI: 10.1242/jeb.243421] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
The gill is the primary site of ionoregulation and gas exchange in adult teleost fishes. However, those characteristics that benefit diffusive gas exchange (large, thin gills) may also enhance the passive equilibration of ions and water that threaten osmotic homeostasis. Our literature review revealed that gill surface area and thickness were similar in freshwater (FW) and seawater (SW) species; however, the diffusive oxygen (O2) conductance (Gd) of the gill was lower in FW species. While a lower Gd may reduce ion losses, it also limits O2 uptake capacity and possibly aerobic performance in situations of high O2 demand (e.g. exercise) or low O2 availability (e.g. environmental hypoxia). We also found that FW fishes had significantly higher haemoglobin (Hb)-O2 binding affinities than SW species, which will increase the O2 diffusion gradient across the gills. Therefore, we hypothesized that the higher Hb-O2 affinity of FW fishes compensates, in part, for their lower Gd. Using a combined literature review and modelling approach, our results show that a higher Hb-O2 affinity in FW fishes increases the flux of O2 across their low-Gd gills. In addition, FW and SW teleosts can achieve similar maximal rates of O2 consumption (ṀO2,max) and hypoxia tolerance (Pcrit) through different combinations of Hb-O2 affinity and Gd. Our combined data identified novel patterns in gill and Hb characteristics between FW and SW fishes and our modelling approach provides mechanistic insight into the relationship between aerobic performance and species distribution ranges, generating novel hypotheses at the intersection of cardiorespiratory and ionoregulatory fish physiology.
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Affiliation(s)
- Till S Harter
- Marine Biology Research Division, Scripps Institution of Oceanography, University of California San Diego, La Jolla, CA 92093, USA
| | - Christian Damsgaard
- Zoophysiology, Department of Biology, Aarhus University, 8000 Aarhus, Denmark.,Aarhus Institute of Advanced Studies, Aarhus University, 8000 Aarhus, Denmark
| | - Matthew D Regan
- Département de sciences biologiques, Université de Montréal, Montreal, QC, Canada, H3T 1J4
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3
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Monteiro DA, Kalinin AL, Rantin FT, McKenzie DJ. Use of complex physiological traits as ecotoxicological biomarkers in tropical freshwater fishes. JOURNAL OF EXPERIMENTAL ZOOLOGY. PART A, ECOLOGICAL AND INTEGRATIVE PHYSIOLOGY 2021; 335:745-760. [PMID: 34529366 DOI: 10.1002/jez.2540] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/31/2021] [Revised: 07/21/2021] [Accepted: 08/02/2021] [Indexed: 06/13/2023]
Abstract
We review the use of complex physiological traits, of tolerance and performance, as biomarkers of the toxicological effects of contaminants in subtropical and tropical freshwater fishes. Such traits are growing in relevance due to climate change, as exposure to contaminants may influence the capacity of fishes to tolerate and perform in an increasingly stressful environment. We review the evidence that the critical oxygen level, a measure of hypoxia tolerance, provides a valuable biomarker of impacts of diverse classes of contaminants. When coupled with measures of cardiorespiratory variables, it can provide insight into mechanisms of toxicity. The critical thermal maximum, a simple measure of tolerance of acute warming, also provides a valuable biomarker despite a lack of understanding of its mechanistic basis. Its relative ease of application renders it useful in the rapid evaluation of multiple species, and in understanding how the severity of contaminant impacts depends upon prevailing environmental temperature. The critical swimming speed is a measure of exercise performance that is widely used as a biomarker in temperate species but very few studies have been performed on subtropical or tropical fishes. Overall, the review serves to highlight a critical lack of knowledge for subtropical and tropical freshwater fishes. There is a real need to expand the knowledge base and to use physiological biomarkers in support of decision making to manage tropical freshwater fish populations and their habitats, which sustain rich biodiversity but are under relentless anthropogenic pressure.
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Affiliation(s)
- Diana A Monteiro
- Department of Physiological Sciences, Federal University of São Carlos (UFSCar), São Carlos, São Paulo, Brazil
| | - Ana L Kalinin
- Department of Physiological Sciences, Federal University of São Carlos (UFSCar), São Carlos, São Paulo, Brazil
| | - F Tadeu Rantin
- Department of Physiological Sciences, Federal University of São Carlos (UFSCar), São Carlos, São Paulo, Brazil
| | - David J McKenzie
- Department of Physiological Sciences, Federal University of São Carlos (UFSCar), São Carlos, São Paulo, Brazil
- UMR Marbec, Univ. Montpellier, CNRS, IRD, Ifremer, Montpellier, France
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4
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Filice M, Cerra MC, Imbrogno S. The goldfish Carassius auratus: an emerging animal model for comparative cardiac research. J Comp Physiol B 2021; 192:27-48. [PMID: 34455483 PMCID: PMC8816371 DOI: 10.1007/s00360-021-01402-9] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2021] [Revised: 08/09/2021] [Accepted: 08/18/2021] [Indexed: 12/12/2022]
Abstract
The use of unconventional model organisms is significantly increasing in different fields of research, widely contributing to advance life sciences understanding. Among fishes, the cyprinid Carassius auratus (goldfish) is largely used for studies on comparative and evolutionary endocrinology, neurobiology, adaptive and conservation physiology, as well as for translational research aimed to explore mechanisms that may be useful in an applicative biomedical context. More recently, the research possibilities offered by the goldfish are further expanded to cardiac studies. A growing literature is available to illustrate the complex networks involved in the modulation of the goldfish cardiac performance, also in relation to the influence of environmental signals. However, an overview on the existing current knowledge is not yet available. By discussing the mechanisms that in C. auratus finely regulate the cardiac function under basal conditions and under environmental challenges, this review highlights the remarkable flexibility of the goldfish heart in relation not only to the basic morpho-functional design and complex neuro-humoral traits, but also to its extraordinary biochemical-metabolic plasticity and its adaptive potential. The purpose of this review is also to emphasize the power of the heart of C. auratus as an experimental tool useful to investigate mechanisms that could be difficult to explore using more conventional animal models and complex cardiac designs.
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Affiliation(s)
- Mariacristina Filice
- Department of Biology, Ecology and Earth Sciences, University of Calabria, 87036, Arcavacata di Rende, CS, Italy.
| | - Maria Carmela Cerra
- Department of Biology, Ecology and Earth Sciences, University of Calabria, 87036, Arcavacata di Rende, CS, Italy
| | - Sandra Imbrogno
- Department of Biology, Ecology and Earth Sciences, University of Calabria, 87036, Arcavacata di Rende, CS, Italy
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Hypoxia Performance Curve: Assess a Whole-Organism Metabolic Shift from a Maximum Aerobic Capacity towards a Glycolytic Capacity in Fish. Metabolites 2021; 11:metabo11070447. [PMID: 34357341 PMCID: PMC8307916 DOI: 10.3390/metabo11070447] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2021] [Revised: 06/29/2021] [Accepted: 07/01/2021] [Indexed: 11/16/2022] Open
Abstract
The utility of measuring whole-animal performance to frame the metabolic response to environmental hypoxia is well established. Progressively reducing ambient oxygen (O2) will initially limit maximum metabolic rate as a result of a hypoxemic state and ultimately lead to a time-limited, tolerance state supported by substrate-level phosphorylation when the O2 supply can no longer meet basic needs (standard metabolic rate, SMR). The metabolic consequences of declining ambient O2 were conceptually framed for fishes initially by Fry's hypoxic performance curve, which characterizes the hypoxemic state and its consequences to absolute aerobic scope (AAS), and Hochachka's concept of scope for hypoxic survival, which characterizes time-limited life when SMR cannot be supported by O2 supply. Yet, despite these two conceptual frameworks, the toolbox to assess whole-animal metabolic performance remains rather limited. Here, we briefly review the ongoing debate concerning the need to standardize the most commonly used assessments of respiratory performance in hypoxic fishes, namely critical O2 (the ambient O2 level below which maintenance metabolism cannot be sustained) and the incipient lethal O2 (the ambient O2 level at which a fish loses the ability to maintain upright equilibrium), and then we advance the idea that the most useful addition to the toolbox will be the limiting-O2 concentration (LOC) performance curve. Using Fry & Hart's (1948) hypoxia performance curve concept, an LOC curve was subsequently developed as an eco-physiological framework by Neil et al. and derived for a group of fish during a progressive hypoxia trial by Claireaux and Lagardère (1999). In the present review, we show how only minor modifications to available respirometry tools and techniques are needed to generate an LOC curve for individual fish. This individual approach to the LOC curve determination then increases its statistical robustness and importantly opens up the possibility of examining individual variability. Moreover, if peak aerobic performance at a given ambient O2 level of each individual is expressed as a percentage of its AAS, the water dissolved O2 that supports 50% of the individual's AAS (DOAAS-50) can be interpolated much like the P50 for an O2 hemoglobin dissociation curve (when hemoglobin is 50% saturated with O2). Thus, critical O2, incipient lethal O2, DOAAS-50 and P50 and can be directly compared within and across species. While an LOC curve for individual fish represents a start to an ongoing need to seamlessly integrate aerobic to anaerobic capacity assessments in a single, multiplexed respirometry trial, we close with a comparative exploration of some of the known whole-organism anaerobic and aerobic capacity traits to examine for correlations among them and guide the next steps.
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6
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Farhat E, Cheng H, Romestaing C, Pamenter M, Weber JM. Goldfish Response to Chronic Hypoxia: Mitochondrial Respiration, Fuel Preference and Energy Metabolism. Metabolites 2021; 11:187. [PMID: 33809959 PMCID: PMC8004290 DOI: 10.3390/metabo11030187] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2021] [Revised: 03/10/2021] [Accepted: 03/17/2021] [Indexed: 12/16/2022] Open
Abstract
Hypometabolism is a hallmark strategy of hypoxia tolerance. To identify potential mechanisms of metabolic suppression, we have used the goldfish to quantify the effects of chronically low oxygen (4 weeks; 10% air saturation) on mitochondrial respiration capacity and fuel preference. The responses of key enzymes from glycolysis, β-oxidation and the tricarboxylic acid (TCA) cycle, and Na+/K+-ATPase were also monitored in various tissues of this champion of hypoxia tolerance. Results show that mitochondrial respiration of individual tissues depends on oxygen availability as well as metabolic fuel oxidized. All the respiration parameters measured in this study (LEAK, OXPHOS, Respiratory Control Ratio, CCCP-uncoupled, and COX) are affected by hypoxia, at least for one of the metabolic fuels. However, no common pattern of changes in respiration states is observed across tissues, except for the general downregulation of COX that may help metabolic suppression. Hypoxia causes the brain to switch from carbohydrates to lipids, with no clear fuel preference in other tissues. It also downregulates brain Na+/K+-ATPase (40%) and causes widespread tissue-specific effects on glycolysis and beta-oxidation. This study shows that hypoxia-acclimated goldfish mainly promote metabolic suppression by adjusting the glycolytic supply of pyruvate, reducing brain Na+/K+-ATPase, and downregulating COX, most likely decreasing mitochondrial density.
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Affiliation(s)
- Elie Farhat
- Biology Department, University of Ottawa, Ottawa, ON K1N 6N5, Canada; (E.F.); (H.C.); (C.R.); (M.P.)
| | - Hang Cheng
- Biology Department, University of Ottawa, Ottawa, ON K1N 6N5, Canada; (E.F.); (H.C.); (C.R.); (M.P.)
| | - Caroline Romestaing
- Biology Department, University of Ottawa, Ottawa, ON K1N 6N5, Canada; (E.F.); (H.C.); (C.R.); (M.P.)
- Univ Lyon, Université Claude Bernard Lyon1, CNRS, ENTPE, UMR 5023, LEHNA, F 69622 Villeurbanne, France
| | - Matthew Pamenter
- Biology Department, University of Ottawa, Ottawa, ON K1N 6N5, Canada; (E.F.); (H.C.); (C.R.); (M.P.)
- Faculty of Medicine, University of Ottawa Brain and Mind Research Institute, University of Ottawa, Ottawa, ON K1H 8M5, Canada
| | - Jean-Michel Weber
- Biology Department, University of Ottawa, Ottawa, ON K1N 6N5, Canada; (E.F.); (H.C.); (C.R.); (M.P.)
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7
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Hossein-Javaheri N, Buck LT. GABA receptor inhibition and severe hypoxia induce a paroxysmal depolarization shift in goldfish neurons. J Neurophysiol 2020; 125:321-330. [PMID: 33296606 DOI: 10.1152/jn.00149.2020] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Mammalian neurons undergo rapid excitotoxic cell death when deprived of oxygen; however, the common goldfish (Carassius auratus) has the unique ability of surviving in oxygen-free waters, under anoxia. This organism utilizes γ-amino butyric acid (GABA) signaling to suppress excitatory glutamatergic activity during anoxic periods. Although GABAA receptor antagonists are not deleterious to the cellular survival, coinhibition of GABAA and GABAB receptors is detrimental by abolishing anoxia-induced neuroprotective mechanisms. Here we show that blocking the anoxic GABAergic neurotransmission induces seizure-like activity (SLA) analogous to a paroxysmal depolarization shift (PDS), with hyperpolarization of action potential (AP) threshold and elevation of threshold currents. The observed PDS was attributed to an increase in excitatory postsynaptic currents (EPSCs) that are normally attenuated with decreasing oxygen levels. Furthermore, for the first time, we show that in addition to PDS, some neurons undergo depolarization block and do not generate AP despite a suprathreshold membrane potential. In conclusion, our results indicate that with severe hypoxia and absence of GABA receptor activity, telencephalic neurons of C. auratus manifest a paroxysmal depolarization shift, a key feature of epileptic discharge.NEW & NOTEWORTHY This work shows that the combination of anoxia and inhibition of GABA receptors induces seizure-like activities in goldfish telencephalic pyramidal and stellate neurons. Importantly, to prevent seizure-like activity, an intact GABA-mediated inhibitory pathway is required.
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Affiliation(s)
| | - Leslie Thomas Buck
- Department of Cell & Systems Biology, University of Toronto, Toronto, Ontario, Canada
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8
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Farhat E, Devereaux MEM, Pamenter ME, Weber JM. Naked mole-rats suppress energy metabolism and modulate membrane cholesterol in chronic hypoxia. Am J Physiol Regul Integr Comp Physiol 2020; 319:R148-R155. [PMID: 32663032 DOI: 10.1152/ajpregu.00057.2020] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Naked mole-rats (NMRs) are mammalian champions of hypoxia tolerance that enter metabolic suppression to survive in low oxygen environments. Common physiological mechanisms used by animals to suppress metabolic rate include downregulating energy metabolism (ATP supply) as well as ion pumps (primary cellular ATP consumers). A recent goldfish study demonstrated that remodeling of membrane lipids may mediate these responses, but it is unknown if NMR employs the same strategies; therefore, we aimed to test the hypotheses that these fossorial mammals 1) downregulate the activity of key enzymes of glycolysis, tricarboxylic acid (TCA) cycle, and β-oxidation, 2) inhibit sodium-potassium-ATPase, and 3) alter membrane lipids in response to chronic hypoxia. We found that NMRs exposed to 11% oxygen for 4 wk had a lower metabolic rate by 34%. This suppression occurs concurrently with tissue-specific 25-99% decreases in metabolic enzymes activities, a 77% decrease in brain sodium/potassium-ATPase activity, and widespread changes in membrane cholesterol abundance. By reducing glycolytic and β-oxidation fluxes, NMRs decrease the supply of acetyl-CoA to the TCA cycle. By contrast, there is a 94% upregulation of citrate synthase in the heart, possibly to support circulation and thus oxygen supply to other organs. Taken together, these responses may reflect a coordinated physiological response to hypoxia, but a clear functional link between changes in membrane composition and enzyme activities could not be established. Nevertheless, this is the first demonstration that hypometabolic NMRs alter the lipid composition of their membranes in response to chronic in vivo exposure to hypoxia.
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Affiliation(s)
- Elie Farhat
- Biology Department, University of Ottawa, Ottawa, Ontario, Canada
| | | | - Matthew E Pamenter
- Biology Department, University of Ottawa, Ottawa, Ontario, Canada.,University of Ottawa Brain and Mind Research Institute, Ottawa, Ontario, Canada
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9
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Borowiec BG, Hoffman RD, Hess CD, Galvez F, Scott GR. Interspecific variation in hypoxia tolerance and hypoxia acclimation responses in killifish from the family Fundulidae. J Exp Biol 2020; 223:jeb209692. [PMID: 31988166 PMCID: PMC7044458 DOI: 10.1242/jeb.209692] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2019] [Accepted: 01/20/2020] [Indexed: 01/25/2023]
Abstract
Hypoxia is a pervasive stressor in aquatic environments, and both phenotypic plasticity and evolutionary adaptation could shape the ability to cope with hypoxia. We investigated evolved variation in hypoxia tolerance and the hypoxia acclimation response across fundulid killifishes that naturally experience different patterns of hypoxia exposure. We compared resting O2 consumption rate (ṀO2 ), and various indices of hypoxia tolerance [critical O2 tension (Pcrit), regulation index (RI), O2 tension (PO2 ) at loss of equilibrium (PLOE) and time to LOE (tLOE) at 0.6 kPa O2] in Fundulus confluentus, Fundulus diaphanus, Fundulus heteroclitus, Fundulus rathbuni, Lucania goodei and Lucania parva We examined the effects of chronic (28 days) exposure to constant hypoxia (2 kPa) or nocturnal intermittent hypoxia (12 h normoxia:12 h hypoxia) in a subset of species. Some species exhibited a two-breakpoint model in ṀO2 caused by early, modest declines in ṀO2 in moderate hypoxia. We found that hypoxia tolerance varied appreciably across species: F. confluentus was the most tolerant (lowest PLOE and Pcrit, longest tLOE), whereas F. rathbuni and F. diaphanus were the least tolerant. However, there was not a consistent pattern of interspecific variation for different indices of hypoxia tolerance, with or without taking phylogenetic relatedness into account, probably because these different indices are underlain by partially distinct mechanisms. Hypoxia acclimation generally improved hypoxia tolerance, but the magnitude of plasticity and responsiveness to different hypoxia patterns varied interspecifically. Our results therefore suggest that hypoxia tolerance is a complex trait that is best appreciated by considering multiple indices of tolerance.
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Affiliation(s)
| | - Ryan D Hoffman
- Department of Biological Sciences, Louisiana State University, Baton Rouge, LA 70803, USA
| | - Chelsea D Hess
- Department of Biological Sciences, Louisiana State University, Baton Rouge, LA 70803, USA
| | - Fernando Galvez
- Department of Biological Sciences, Louisiana State University, Baton Rouge, LA 70803, USA
| | - Graham R Scott
- Department of Biology, McMaster University, Hamilton, ON, Canada, L8S 4K1
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10
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Abstract
The diversity of fish hemoglobins and the association with oxygen availability and physiological requirements during the life cycle has attracted scientists since the first report on multiple hemoglobin in fishes (Buhler and Shanks 1959). The functional heterogeneity of the fish hemoglobins enables many species to tolerate hypoxic conditions and exhausting swimming, but also to maintain the gas pressure in the swim bladder at large depths. The hemoglobin repertoire has further increased in various species displaying polymorphic hemoglobin variants differing in oxygen binding properties. The multiplicity of fish hemoglobins as particularly found in the tetraploid salmonids strongly contrasts with the complete loss of hemoglobins in Antarctic icefishes and illustrates the adaptive radiation in the oxygen transport of this successful vertebrate group.
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Affiliation(s)
- Øivind Andersen
- Norwegian Institute of Food, Fisheries and Aquaculture Research (NOFIMA), PO BOX 210,1431, Ås, Norway.
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11
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MS-based proteomic analysis of cardiac response to hypoxia in the goldfish (Carassius auratus). Sci Rep 2019; 9:18953. [PMID: 31831848 PMCID: PMC6908699 DOI: 10.1038/s41598-019-55497-w] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2019] [Accepted: 10/25/2019] [Indexed: 12/19/2022] Open
Abstract
The exceptional hypoxia tolerance of the goldfish heart may be achieved through the activation of an alternative mechanism recruiting the first product of the anaerobic glycolysis (i.e. piruvate). This hypothesis led to design a classical mass spectrometry based proteomic study to identify in the goldfish cardiac proteins that may be associated with maintaining heart function under normoxia and hypoxia. A selective protein solubilization, SDS PAGE, trypsin digestion and MALDI MS/MS analysis allowed the identification of the 12 most stable hypoxia-regulated proteins. Among these proteins, five are enzymes catalyzing reversible steps of the glycolysis/gluconeogenesis network. Protein composition reveals the presence of fructose-1,6-bisphosphate aldolase B as a specific hypoxia-regulated protein. This work indicated that the key enzyme of reversible steps of the glycolysis/gluconeogenesis network is fructose-1,6-bisphosphate, aldolase B, suggesting a role of gluconeogenesis in the mechanisms involved in the goldfish heart response to hypoxia.
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12
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Burggren WW, Arriaga-Bernal JC, Méndez-Arzate PM, Méndez-Sánchez JF. Metabolic physiology of the Mayan cichlid fish (Mayaheros uropthalmus): Re-examination of classification as an oxyconformer. Comp Biochem Physiol A Mol Integr Physiol 2019; 237:110538. [DOI: 10.1016/j.cbpa.2019.110538] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2019] [Revised: 08/05/2019] [Accepted: 08/07/2019] [Indexed: 11/16/2022]
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13
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Clarke SB, Chapman LJ, Krahe R. The effect of normoxia exposure on hypoxia tolerance and sensory sampling in a swamp-dwelling mormyrid fish. Comp Biochem Physiol A Mol Integr Physiol 2019; 240:110586. [PMID: 31648062 DOI: 10.1016/j.cbpa.2019.110586] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2019] [Revised: 09/22/2019] [Accepted: 09/23/2019] [Indexed: 11/27/2022]
Abstract
Effects of energetic limitations on the performance of sensory systems are generally difficult to quantify. Weakly electric fishes provide an ideal model system to quantify the effects of metabolic stressors on sensory information acquisition, because they use an active-sensing strategy that permits easy measurement of the sensing effort. These fishes discharge an electric signal and sense perturbations of the resulting electric field. We used the mormyrid Petrocephalus degeni to quantify the relationship between routine metabolic rate and the rate of sensory sampling (rate of electric organ discharge, EOD) while under progressive hypoxia by quantifying the critical oxygen tension (PC-MR) and the critical electric organ discharge threshold (PC-EOD). PC-MR was significantly higher in fish acclimated to normoxia for over 40 days compared to animals tested within 1-5 days of capture from a hypoxic swamp, which suggests high costs of maintaining hypoxia tolerance; however, there was no acclimation effect on PC-EOD. All P. degeni reached their PC-EOD prior to their PC-MR. However, below the respective critical tension value, EOD rate decreased more gradually than the metabolic rate suggesting that the fish were increasing the proportion of their energy budget allocated to acquiring sensory information as dissolved-oxygen levels dropped. Trade-offs between sensory sampling and other physiological functions are also suggested by the increase in routine EOD rate with long-term normoxia acclimation, in contrast to metabolic rate, which showed no significant changes. These results highlight the relationship between sensory sampling and metabolic rate in response to progressive hypoxia and the plasticity of hypoxia tolerance.
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Affiliation(s)
- Shelby B Clarke
- Department of Biology, McGill University, 1205 Ave du Docteur-Penfield, Montreal, QC H3A1B1, Canada.
| | - Lauren J Chapman
- Department of Biology, McGill University, 1205 Ave du Docteur-Penfield, Montreal, QC H3A1B1, Canada.
| | - Rüdiger Krahe
- Department of Biology, McGill University, 1205 Ave du Docteur-Penfield, Montreal, QC H3A1B1, Canada; Humboldt-Universität zu Berlin, Institute of Biology, Unter den Linden 6, 10099 Berlin, Germany.
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14
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Farhat E, Turenne ED, Choi K, Weber JM. Hypoxia-induced remodelling of goldfish membranes. Comp Biochem Physiol B Biochem Mol Biol 2019; 237:110326. [PMID: 31465877 DOI: 10.1016/j.cbpb.2019.110326] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2019] [Revised: 08/21/2019] [Accepted: 08/22/2019] [Indexed: 12/18/2022]
Abstract
Hypoxia-tolerant animals use metabolic suppression as an essential strategy to survive low oxygen. Ectotherms can alter membrane lipid composition in response to changes in environmental temperature, but it is currently unknown whether chronic hypoxia can also elicit membrane restructuring. The goal of this study was to investigate a possible physiological link between membrane remodelling and metabolic suppression in goldfish exposed to prolonged hypoxia (4 weeks at 10% air saturation). We have tested the hypothesis that chronic hypoxia would modulate membrane lipid composition in ways that are consistent with known mechanisms of ion pump inhibition. Because homeoviscous membrane restructuring could interfere with the response to hypoxia, measurements were made at 2 temperatures. Results show that hypoxic goldfish suppress metabolic rate by 74% (at 13 °C) and 63% (at 20 °C). This study is the first to reveal that cold-acclimated animals undergo extensive, tissue-specific restructuring of membrane lipids as they reach minimal metabolic rates. However, hypoxia does not affect membrane composition in fish acclimated to 20 °C. The strong membrane response of cold-acclimated fish involves increases in cholesterol abundance (in white muscle and gills) and in fatty acid saturation, mainly caused by a reduction in %22:6 (docosahexaenoic acid in gills and liver). Major ion pumps like Na+/K+-ATPase are known to be inhibited by cholesterol and activated by 22:6. Because ion pumping by membrane-bound ATPases accounts for a large fraction of basal cellular energy use, we propose that the membrane responses reported here could be a novel mechanism to promote metabolic suppression in cold-acclimated animals.
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Affiliation(s)
- Elie Farhat
- Biology Department, University of Ottawa, Ottawa, Ontario, Canada
| | - Eric D Turenne
- Biology Department, University of Ottawa, Ottawa, Ontario, Canada
| | - Kevin Choi
- Biology Department, University of Ottawa, Ottawa, Ontario, Canada
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15
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Burggren WW, Mendez-Sanchez JF, Martínez Bautista G, Peña E, Martínez García R, Alvarez González CA. Developmental changes in oxygen consumption and hypoxia tolerance in the heat and hypoxia-adapted tabasco line of the Nile tilapia Oreochromis niloticus, with a survey of the metabolic literature for the genus Oreochromis. JOURNAL OF FISH BIOLOGY 2019; 94:732-744. [PMID: 30847924 DOI: 10.1111/jfb.13945] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/07/2018] [Accepted: 03/01/2019] [Indexed: 06/09/2023]
Abstract
The genus Oreochromis is among the most popular of the tilapiine cichlid tribe for aquaculture. However, their temperature and hypoxia tolerance, if tested at all, is usually tested at temperatures of 20-25°C, rather than at the considerably higher temperatures of 30-35°C typical of tropical aquaculture. We hypothesized that both larvae and adults of the heat and hypoxia-adapted Tabasco-line of the Nile tilapia Oreochromis niloticus would be relatively hypoxia-tolerant. Oxygen consumption rate ( M ˙ O 2 ), Q10 and aquatic surface respiration (ASR) was measured using closed respirometry at 2 (c. 0.2 g), 30 (c. 2-5 g), 105 c. (10-15 g) and 240 (c. 250 g) days of development, at 25°C, 30°C and 35°C. M ˙ O 2 at 30°C was inversely related to body mass: c. 90 μM O2 g-1 /h in larvae down to c. 1 μM O2 g-1 /h in young adults. Q10 for M ˙ O 2 was typical for fish over the range 25-35°C of 1.5-2.0. ASR was exhibited by 50% of the fish at pO2 of 15-50 mmHg in a temperature-dependent fashion. However, the largest adults showed notable ASR only when pO2 fell to below 10 mmHg. Remarkably, pcrit for M ˙ O 2 was 12-17 mmHg at 25-30°C and still only 20-25 mmHg across development at 35°C. These values are among the lowest measured for teleost fishes. Noteworthy is that all fish maintain equilibrium, ventilated their gills and showed routine locomotor action for 10-20 min after M ˙ O 2 ceased at near anoxia and when then returned to oxygenated waters, all fish survived, further indicating a remarkable hypoxic tolerance. Remarkably, data assembled for M ˙ O 2 from >30 studies showed a > x2000 difference, which we attribute to calculation or conversion errors. Nonetheless, pcrit was very low for all Oreochromis sp. and lowest in the heat and hypoxia-adapted Tabasco line.
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Affiliation(s)
- Warren W Burggren
- Developmental Integrative Biology Group, Department of Biology, University of North Texas, Denton, Texas, USA
| | - Jose F Mendez-Sanchez
- Laboratorio de Ecofisiología Animal, Facultad de Ciencias, Universidad Autónoma del Estado de México, Toluca, Mexico
| | - Gil Martínez Bautista
- Laboratorio de Acuicultura Tropical, División Académica de Ciencias Biológicas, Universidad Juárez Autónoma de Tabasco, Villahermosa, Mexico
| | - Emyr Peña
- Laboratorio de Acuicultura Tropical, División Académica de Ciencias Biológicas, Universidad Juárez Autónoma de Tabasco, Villahermosa, Mexico
| | - Rafael Martínez García
- Laboratorio de Acuicultura Tropical, División Académica de Ciencias Biológicas, Universidad Juárez Autónoma de Tabasco, Villahermosa, Mexico
| | - Carlos A Alvarez González
- Laboratorio de Acuicultura Tropical, División Académica de Ciencias Biológicas, Universidad Juárez Autónoma de Tabasco, Villahermosa, Mexico
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16
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Regan MD, Mandic M, Dhillon RS, Lau GY, Farrell AP, Schulte PM, Seibel BA, Speers-Roesch B, Ultsch GR, Richards JG. Don't throw the fish out with the respirometry water. J Exp Biol 2019; 222:222/6/jeb200253. [DOI: 10.1242/jeb.200253] [Citation(s) in RCA: 33] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Affiliation(s)
- Matthew D. Regan
- Department of Comparative Biosciences, University of Wisconsin-Madison, Madison, WI 53706, USA
| | - Milica Mandic
- Department of Biology, University of Ottawa, Ottawa, ON, Canada, K1N 6N5
| | - Rashpal S. Dhillon
- Department of Biomolecular Chemistry, University of Wisconsin-Madison, Madison, WI 53706, USA
| | - Gigi Y. Lau
- Department of Biosciences, University of Oslo, PO Box 1066, Blindern, 0316 Oslo, Norway
| | - Anthony P. Farrell
- Department of Zoology, University of British Columbia, Vancouver, BC, Canada, V6T 1Z4
- Faculty of Land and Food Systems, University of British Columbia, Vancouver, BC, Canada, V6T 1Z4
| | - Patricia M. Schulte
- Department of Zoology, University of British Columbia, Vancouver, BC, Canada, V6T 1Z4
| | - Brad A. Seibel
- College of Marine Science, University of South Florida, St Petersburg, FL 33701, USA
| | - Ben Speers-Roesch
- Department of Biological Sciences, University of New Brunswick-Saint John, PO Box 5050, Saint John, NB, Canada, E2L 4L5
| | - Gordon R. Ultsch
- Department of Biology, University of Florida, Gainesville, FL 32611, USA
| | - Jeffrey G. Richards
- Department of Zoology, University of British Columbia, Vancouver, BC, Canada, V6T 1Z4
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17
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Borowiec BG, McClelland GB, Rees BB, Scott GR. Distinct metabolic adjustments arise from acclimation to constant hypoxia and intermittent hypoxia in estuarine killifish (Fundulus heteroclitus). J Exp Biol 2018; 221:221/23/jeb190900. [DOI: 10.1242/jeb.190900] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2018] [Accepted: 10/16/2018] [Indexed: 12/15/2022]
Abstract
ABSTRACT
Many fish experience daily cycles of hypoxia in the wild, but the physiological strategies for coping with intermittent hypoxia are poorly understood. We examined how killifish adjust O2 supply and demand during acute hypoxia, and how these responses are altered after prolonged acclimation to constant or intermittent patterns of hypoxia exposure. We acclimated killifish to normoxia (∼20 kPa O2), constant hypoxia (2 kPa) or intermittent cycles of nocturnal hypoxia (12 h:12 h normoxia:hypoxia) for 28 days, and then compared whole-animal O2 consumption rates (ṀO2) and tissue metabolites during exposure to 12 h of hypoxia followed by reoxygenation in normoxia. Normoxia-acclimated fish experienced a pronounced 27% drop in ṀO2 during acute hypoxia, and modestly increased ṀO2 upon reoxygenation. They strongly recruited anaerobic metabolism during acute hypoxia, indicated by lactate accumulation in plasma, muscle, liver, brain, heart and digestive tract, as well as a transient drop in intracellular pH, and they increased hypoxia inducible factor (HIF)-1α protein abundance in muscle. Glycogen, glucose and glucose-6-phosphate levels suggested that glycogen supported brain metabolism in hypoxia, while the muscle used circulating glucose. Acclimation to constant hypoxia caused a stable ∼50% decrease in ṀO2 that persisted after reoxygenation, with minimal recruitment of anaerobic metabolism, suggestive of metabolic depression. By contrast, fish acclimated to intermittent hypoxia maintained sufficient O2 transport to support normoxic ṀO2, modestly recruited lactate metabolism and increased ṀO2 dramatically upon reoxygenation. Both groups of hypoxia-acclimated fish had similar glycogen, ATP, intracellular pH and HIF-1α levels as normoxic controls. We conclude that different patterns of hypoxia exposure favour distinct strategies for matching O2 supply and O2 demand.
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Affiliation(s)
| | - Grant B. McClelland
- Department of Biology, McMaster University, Hamilton, Ontario, Canada, L8S 4K1
| | - Bernard B. Rees
- Department of Biological Sciences, University of New Orleans, New Orleans, LA 70148, USA
| | - Graham R. Scott
- Department of Biology, McMaster University, Hamilton, Ontario, Canada, L8S 4K1
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18
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Wood CM. The fallacy of the P crit - are there more useful alternatives? ACTA ACUST UNITED AC 2018; 221:221/22/jeb163717. [PMID: 30420494 DOI: 10.1242/jeb.163717] [Citation(s) in RCA: 67] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
P crit - generally defined as the P O2 below which the animal can no longer maintain a stable rate of O2 consumption (Ṁ O2 ), such that Ṁ O2 becomes dependent upon P O2 - provides a single number into which a vast amount of experimental effort has been invested. Here, with specific reference to water-breathers, I argue that this focus on the P crit is not useful for six reasons: (1) calculation of P crit usually involves selective data editing; (2) the value of P crit depends greatly on the way it is determined; (3) there is no good theoretical justification for the concept; (4) P crit is not the transition point from aerobic to anaerobic metabolism, and it disguises what is really going on; (5) P crit is not a reliable index of hypoxia tolerance; and (6) P crit carries minimal information content. Preferable alternatives are loss of equilibrium (LOE) tests for hypoxia tolerance, and experimental description of full Ṁ O2 versus P O2 profiles accompanied by measurements of ventilation, lactate appearance and metabolic rate by calorimetry. If the goal is to assess the ability of the animal to regulate Ṁ O2 from this profile in a mathematical fashion, promising, more informative alternatives to P crit are the regulation index and Michaelis-Menten or sigmoidal allosteric analyses.
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Affiliation(s)
- Chris M Wood
- Department of Zoology, University of British Columbia, Vancouver, BC, Canada V6T 1Z4 .,Department of Biology, McMaster University, Hamilton, ON, Canada L8S 4K1.,Rosenstiel School of Marine and Atmospheric Science, University of Miami, FL 33149, USA
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19
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Mandic M, Regan MD. Can variation among hypoxic environments explain why different fish species use different hypoxic survival strategies? ACTA ACUST UNITED AC 2018; 221:221/21/jeb161349. [PMID: 30381477 DOI: 10.1242/jeb.161349] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
In aquatic environments, hypoxia is a multi-dimensional stressor that can vary in O2 level (partial pressure of O2 in water, PwO2 ), rate of induction and duration. Natural hypoxic environments can therefore be very different from one another. For the many fish species that have evolved to cope with these different hypoxic environments, survival requires adjusting energy supply and demand pathways to maintain energy balance. The literature describes innumerable ways that fishes combine aerobic metabolism, anaerobic metabolism and metabolic rate depression (MRD) to accomplish this, but it is unknown whether the evolutionary paths leading to these different strategies are determined primarily by species' phylogenetic histories, genetic constraint or their native hypoxic environments. We explored this idea by devising a four-quadrant matrix that bins different aquatic hypoxic environments according to their duration and PwO2 characteristics. We then systematically mined the literature for well-studied species native to environments within each quadrant, and, for each of 10 case studies, described the species' total hypoxic response (THR), defined as its hypoxia-induced combination of sustained aerobic metabolism, enhanced anaerobic metabolism and MRD, encompassing also the mechanisms underlying these metabolic modes. Our analysis revealed that fishes use a wide range of THRs, but that distantly related species from environments within the same matrix quadrant have converged on similar THRs. For example, environments of moderately hypoxic PwO2 favoured predominantly aerobic THRs, whereas environments of severely hypoxic PwO2 favoured MRD. Capacity for aerial emergence as well as predation pressure (aquatic and aerial) also contributed to these responses, in addition to other biotic and abiotic factors. Generally, it appears that the particular type of hypoxia experienced by a fish plays a major role in shaping its particular THR.
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Affiliation(s)
- Milica Mandic
- Department of Biology, University of Ottawa, Ottawa, ON, Canada, K1N 6N5
| | - Matthew D Regan
- Comparative Biosciences Department, University of Wisconsin-Madison, Madison, WI 35706, USA
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20
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Regan MD, Gill IS, Richards JG. Metabolic depression and the evolution of hypoxia tolerance in threespine stickleback, Gasterosteus aculeatus. Biol Lett 2018; 13:rsbl.2017.0392. [PMID: 29093174 DOI: 10.1098/rsbl.2017.0392] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2017] [Accepted: 10/10/2017] [Indexed: 11/12/2022] Open
Abstract
Anthropogenic increases in global temperature and agricultural runoff are increasing the prevalence of aquatic hypoxia throughout the world. We investigated the potential for a relatively rapid evolution of hypoxia tolerance using two isolated (for less than 11 000 years) populations of threespine stickleback: one from a lake that experiences long-term hypoxia (Alta Lake, British Columbia) and one from a lake that does not (Trout Lake, British Columbia). Loss-of-equilibrium (LOE) experiments revealed that the Alta Lake stickleback were significantly more tolerant of hypoxia than the Trout Lake stickleback, and calorimetry experiments revealed that the enhanced tolerance of Alta Lake stickleback may be associated with their ability to depress metabolic rate (as indicated by metabolic heat production) by 33% in hypoxia. The two populations showed little variation in their capacities for O2 extraction and anaerobic metabolism. These results reveal that intraspecific variation in hypoxia tolerance can develop over relatively short geological timescales, as can metabolic rate depression, a complex biochemical response that may be favoured in long-term hypoxic environments.
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Affiliation(s)
- Matthew D Regan
- Department of Zoology, University of British Columbia, 6270 University Boulevard, Vancouver, British Columbia, Canada V6T 1Z4
| | - Ivan S Gill
- Department of Zoology, University of British Columbia, 6270 University Boulevard, Vancouver, British Columbia, Canada V6T 1Z4
| | - Jeffrey G Richards
- Department of Zoology, University of British Columbia, 6270 University Boulevard, Vancouver, British Columbia, Canada V6T 1Z4
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21
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Ruiz T, Bec A, Danger M, Koussoroplis AM, Aguer JP, Morel JP, Morel-Desrosiers N. A microcalorimetric approach for investigating stoichiometric constraints on the standard metabolic rate of a small invertebrate. Ecol Lett 2018; 21:1714-1722. [DOI: 10.1111/ele.13137] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2018] [Revised: 05/07/2018] [Accepted: 07/20/2018] [Indexed: 12/11/2022]
Affiliation(s)
- Thomas Ruiz
- Université Clermont Auvergne; CNRS; LMGE; Clermont-Ferrand F-63000 France
| | - Alexandre Bec
- Université Clermont Auvergne; CNRS; LMGE; Clermont-Ferrand F-63000 France
| | | | | | - Jean-Pierre Aguer
- Université Clermont Auvergne; CNRS; LMGE; Clermont-Ferrand F-63000 France
| | - Jean-Pierre Morel
- Université Clermont Auvergne; CNRS; LMGE; Clermont-Ferrand F-63000 France
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22
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50 years of comparative biochemistry: The legacy of Peter Hochachka. Comp Biochem Physiol B Biochem Mol Biol 2018; 224:1-11. [PMID: 29501788 DOI: 10.1016/j.cbpb.2018.02.002] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2018] [Revised: 02/05/2018] [Accepted: 02/07/2018] [Indexed: 12/29/2022]
Abstract
Peter Hochachka was an early pioneer in the field of comparative biochemistry. He passed away in 2002 after 4 decades of research in the discipline. To celebrate his contributions and to coincide with what would have been his 80th birthday, a group of his former students organized a symposium that ran as a satellite to the 2017 Canadian Society of Zoologists annual meeting in Winnipeg, Manitoba (Canada). This Special Issue of CBP brings together manuscripts from symposium attendees and other authors who recognize the role Peter played in the evolution of the discipline. In this article, the symposium organizers and guest editors look back on his career, celebrating his many contributions to research, acknowledging his role in training of generations of graduate students and post-doctoral fellows in comparative biochemistry and physiology.
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23
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Griko Y, Regan MD. Synthetic torpor: A method for safely and practically transporting experimental animals aboard spaceflight missions to deep space. LIFE SCIENCES IN SPACE RESEARCH 2018; 16:101-107. [PMID: 29475515 DOI: 10.1016/j.lssr.2018.01.002] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/08/2017] [Revised: 01/09/2018] [Accepted: 01/11/2018] [Indexed: 06/08/2023]
Abstract
Animal research aboard the Space Shuttle and International Space Station has provided vital information on the physiological, cellular, and molecular effects of spaceflight. The relevance of this information to human spaceflight is enhanced when it is coupled with information gleaned from human-based research. As NASA and other space agencies initiate plans for human exploration missions beyond low Earth orbit (LEO), incorporating animal research into these missions is vitally important to understanding the biological impacts of deep space. However, new technologies will be required to integrate experimental animals into spacecraft design and transport them beyond LEO in a safe and practical way. In this communication, we propose the use of metabolic control technologies to reversibly depress the metabolic rates of experimental animals while in transit aboard the spacecraft. Compared to holding experimental animals in active metabolic states, the advantages of artificially inducing regulated, depressed metabolic states (called synthetic torpor) include significantly reduced mass, volume, and power requirements within the spacecraft owing to reduced life support requirements, and mitigated radiation- and microgravity-induced negative health effects on the animals owing to intrinsic physiological properties of torpor. In addition to directly benefitting animal research, synthetic torpor-inducing systems will also serve as test beds for systems that may eventually hold human crewmembers in similar metabolic states on long-duration missions. The technologies for inducing synthetic torpor, which we discuss, are at relatively early stages of development, but there is ample evidence to show that this is a viable idea and one with very real benefits to spaceflight programs. The increasingly ambitious goals of world's many spaceflight programs will be most quickly and safely achieved with the help of animal research systems transported beyond LEO; synthetic torpor may enable this to be done as practically and inexpensively as possible.
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Affiliation(s)
- Yuri Griko
- NASA Ames Research Center, Moffett Field, CA 94035, United States.
| | - Matthew D Regan
- University of Wisconsin-Madison, School of Veterinary Medicine, Madison, WI 53706, United States
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24
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Dhillon RS, Mandic M, Yao L, Cao ZD, Fu SJ, Brauner CJ, Wang YS, Richards JG. Ethanol metabolism varies with hypoxia tolerance in ten cyprinid species. J Comp Physiol B 2017; 188:283-293. [PMID: 29032388 DOI: 10.1007/s00360-017-1131-4] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2017] [Revised: 09/22/2017] [Accepted: 10/07/2017] [Indexed: 11/25/2022]
Abstract
During periods of severe hypoxia or anoxia, Carassius spp. are known for their ability to produce ethanol as their anaerobic end product, which diffuses into the environment thereby reducing the osmotic and acidotic load associated with "anaerobic" glycolysis. However, the relationship between alcohol dehydrogenase (ADH) and acetaldehyde dehydrogenase (ALDH) activities, key ethanol metabolizing enzymes, and hypoxia tolerance among Carassius spp. and their closely related non-ethanol-producing cyprinids remains unclear. To address this, we quantified the activity levels of key anaerobic enzymes in liver and muscle in species of cyprinids over 48 h of severe hypoxia exposure (0.7 kPa). As predicted, muscle ADH activity was highest in the two most hypoxia-tolerant species (Carassius spp.), with very low levels present in the other species examined. However, liver ADH activities showed an inverse relationship with hypoxia tolerance, with the most hypoxia-tolerant fish having the lowest ADH activity. There was no correlation between hypoxia tolerance and ALDH and LDH activities in muscle or liver. All species produced lactate, reaching their highest levels after 8 h, but returning to near-baseline levels by 48 h of sustained exposure to hypoxia, suggesting lactate oxidation or depressed ATP demand. Liver glycogen content was not affected by 48 h hypoxia exposure in the most hypoxia-tolerant species, whereas the least tolerant species consumed the majority of the liver glycogen stores, which is probably due to the greater relative hypoxia exposure experienced by these species. Our findings that liver ADH activities were inversely related to hypoxia tolerance suggests that in all but Carassius spp., the ethanol metabolizing pathways in cyprinids is largely similar to that observed in other vertebrates and plays a role in the detoxification of ethanol. Furthermore, conservation of glycogen stores may be the result of metabolic-depressing pathways in the more tolerant species, regardless of the ability to produce ethanol, or adaptations that improve oxygen uptake to reduce metabolic demands due to hypoxia.
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Affiliation(s)
- Rashpal S Dhillon
- Department of Biomolecular Chemistry, University of Wisconsin, 330 North Orchard Street, Madison, WI, 53715, USA.
- Department of Zoology, University of British Columbia, 6270 University Boulevard, Vancouver, BC, V6T 1Z4, Canada.
| | - Milica Mandic
- Department of Biology, University of Ottawa, 30 Marie Curie Private, Ottawa, ON, K1N 6N5, Canada
| | - Lili Yao
- Department of Biomolecular Chemistry, University of Wisconsin, 330 North Orchard Street, Madison, WI, 53715, USA
| | - Zhen-Dong Cao
- Laboratory of Evolutionary Physiology and Behaviour, Chongqing Key Laboratory of Animal Biology, Chongqing Normal University, Chongqing, China
| | - Shi-Jian Fu
- Laboratory of Evolutionary Physiology and Behaviour, Chongqing Key Laboratory of Animal Biology, Chongqing Normal University, Chongqing, China
| | - Colin J Brauner
- Department of Zoology, University of British Columbia, 6270 University Boulevard, Vancouver, BC, V6T 1Z4, Canada
| | - Yuxiang S Wang
- Department of Biology, Queen's University, 116 Barrie Street, Kingston, ON, K7L 3N6, Canada
| | - Jeffrey G Richards
- Department of Zoology, University of British Columbia, 6270 University Boulevard, Vancouver, BC, V6T 1Z4, Canada
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25
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Zhang Y, Mauduit F, Farrell AP, Chabot D, Ollivier H, Rio-Cabello A, Le Floch S, Claireaux G. Exposure of European sea bass (Dicentrarchus labrax) to chemically dispersed oil has a chronic residual effect on hypoxia tolerance but not aerobic scope. AQUATIC TOXICOLOGY (AMSTERDAM, NETHERLANDS) 2017; 191:95-104. [PMID: 28806602 DOI: 10.1016/j.aquatox.2017.07.020] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/09/2017] [Revised: 07/27/2017] [Accepted: 07/31/2017] [Indexed: 06/07/2023]
Abstract
We tested the hypothesis that the chronic residual effects of an acute exposure of European sea bass (Dicentrarchus labrax) to chemically dispersed crude oil is manifest in indices of hypoxic performance rather than aerobic performance. Sea bass were pre-screened with a hypoxia challenge test to establish their incipient lethal oxygen saturation (ILOS), but on discovering a wide breadth for individual ILOS values (2.6-11.0% O2 saturation), fish were subsequently subdivided into either hypoxia sensitive (HS) or hypoxia tolerant (HT) phenotypes, traits that were shown to be experimentally repeatable. The HT phenotype had a lower ILOS and critical oxygen saturation (O2crit) compared with the HS phenotype and switched to glycolytic metabolism at a lower dissolved oxygen, even though both phenotypes accumulated lactate and glucose to the same plasma concentrations at ILOS. As initially hypothesized, and regardless of the phenotype considered, we found no residual effect of oil on any of the indices of aerobic performance. Contrary to our hypothesis, however, oil exposure had no residual effect on any of the indices of hypoxic performance in the HS phenotype. In the HT phenotype, on the other hand, oil exposure had residual effects as illustrated by the impaired repeatability of hypoxia tolerance and also by the 24% increase in O2crit, the 40% increase in scope for oxygen deficit, the 17% increase in factorial scope for oxygen deficit and the 57% increase in accumulated oxygen deficit. Thus, sea bass with a HT phenotype remained chronically impaired for a minimum of 167days following an acute 24-h oil exposure while the HS phenotypes did not. We reasoned that impaired oxygen extraction at gill due to oil exposure activates glycolytic metabolism at a higher dissolved oxygen, conferring on the HT phenotype an inferior hypoxia resistance that might eventually compromise their ability to survive hypoxic episodes.
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Affiliation(s)
- Yangfan Zhang
- Department of Zoology & Faculty of Land and Food System, University of British Columbia, Vancouver, British Columbia, Canada.
| | - Florian Mauduit
- Université de Bretagne Occidentale, Laboratoire des Sciences de l'Environnement Marin (UMR-6539), Unité PFOM-ARN, Ifremer Centre de Bretagne, Plouzané, France
| | - Anthony P Farrell
- Department of Zoology & Faculty of Land and Food System, University of British Columbia, Vancouver, British Columbia, Canada
| | - Denis Chabot
- Maurice Lamontagne Institute, Fisheries & Oceans Canada, Mont-Joli, QC, G5H 3Z4, Canada
| | - Hélène Ollivier
- Université de Bretagne Occidentale, Laboratoire des Sciences de l'Environnement Marin (UMR-6539), Unité PFOM-ARN, Ifremer Centre de Bretagne, Plouzané, France
| | - Adrien Rio-Cabello
- Université de Bretagne Occidentale, Laboratoire des Sciences de l'Environnement Marin (UMR-6539), Unité PFOM-ARN, Ifremer Centre de Bretagne, Plouzané, France
| | - Stéphane Le Floch
- Centre de documentation, de recherche et d'expérimentations sur les pollutions accidentelles des eaux, Brest, France
| | - Guy Claireaux
- Université de Bretagne Occidentale, Laboratoire des Sciences de l'Environnement Marin (UMR-6539), Unité PFOM-ARN, Ifremer Centre de Bretagne, Plouzané, France
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26
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Regan MD, Richards JG. Rates of hypoxia induction alter mechanisms of O 2 uptake and the critical O 2 tension of goldfish. ACTA ACUST UNITED AC 2017; 220:2536-2544. [PMID: 28476894 DOI: 10.1242/jeb.154948] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2016] [Accepted: 05/02/2017] [Indexed: 12/23/2022]
Abstract
The rate of hypoxia induction (RHI) is an important but overlooked dimension of environmental hypoxia that may affect an organism's survival. We hypothesized that, compared with rapid RHI, gradual RHI will afford an organism more time to alter plastic phenotypes associated with O2 uptake and subsequently reduce the critical O2 tension (Pcrit) of the rate of O2 uptake (ṀO2 ). We investigated this by determining Pcrit values for goldfish exposed to short (∼24 min), typical (∼84 min) and long (∼480 min) duration Pcrit trials to represent different RHIs. Consistent with our predictions, long duration Pcrit trials yielded significantly lower Pcrit values (1.0-1.4 kPa) than short and typical duration trials, which did not differ (2.6±0.3 and 2.5±0.2 kPa, respectively). Parallel experiments revealed these time-related shifts in Pcrit were associated with changes to aspects of the O2 transport cascade that took place over the hypoxia exposures: gill surface areas and haemoglobin-O2 binding affinities were significantly higher in fish exposed to gradual RHIs over 480 min than fish exposed to rapid RHIs over 60 min. Our results also revealed that the choice of respirometric technique (i.e. closed versus intermittent) does not affect Pcrit or routine ṀO2 , despite the significantly reduced water pH and elevated CO2 and ammonia levels measured following closed-circuit Pcrit trials of ∼90 min. Together, our results demonstrate that gradual RHIs result in alterations to physiological parameters that enhance O2 uptake in hypoxic environments. An organism's innate Pcrit is therefore most accurately determined using rapid RHIs (<90 min) so as to avoid the confounding effects of hypoxic acclimation.
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Affiliation(s)
- Matthew D Regan
- Department of Zoology, University of British Columbia, 6270 University Blvd, Vancouver, British Columbia, Canada V6T 1Z4
| | - Jeffrey G Richards
- Department of Zoology, University of British Columbia, 6270 University Blvd, Vancouver, British Columbia, Canada V6T 1Z4
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27
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Harter TS, Brauner CJ. The O 2 and CO 2 Transport System in Teleosts and the Specialized Mechanisms That Enhance Hb–O 2 Unloading to Tissues. ACTA ACUST UNITED AC 2017. [DOI: 10.1016/bs.fp.2017.09.001] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
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