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Snead AA, Tatarenkov A, Avise JC, Taylor DS, Turner BJ, Marson K, Earley RL. Out to sea: ocean currents and patterns of asymmetric gene flow in an intertidal fish species. Front Genet 2023; 14:1206543. [PMID: 37456662 PMCID: PMC10349204 DOI: 10.3389/fgene.2023.1206543] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2023] [Accepted: 06/14/2023] [Indexed: 07/18/2023] Open
Abstract
Passive dispersal via wind or ocean currents can drive asymmetric gene flow, which influences patterns of genetic variation and the capacity of populations to evolve in response to environmental change. The mangrove rivulus fish (Kryptolebias marmoratus), hereafter "rivulus," is an intertidal fish species restricted to the highly fragmented New World mangrove forests of Central America, the Caribbean, the Bahamas, and Florida. Mangrove patches are biological islands with dramatic differences in both abiotic and biotic conditions compared to adjacent habitat. Over 1,000 individual rivulus across 17 populations throughout its range were genotyped at 32 highly polymorphic microsatellites. Range-wide population genetic structure was evaluated with five complementary approaches that found eight distinct population clusters. However, an analysis of molecular variance indicated significant population genetic structure among regions, populations within regions, sampling locations within populations, and individuals within sampling locations, indicating that rivulus has both broad- and fine-scale genetic differentiation. Integrating range-wide genetic data with biophysical modeling based on 10 years of ocean current data showed that ocean currents and the distance between populations over water drive gene flow patterns on broad scales. Directional migration estimates suggested some significant asymmetries in gene flow that also were mediated by ocean currents and distance. Specifically, populations in the center of the range (Florida Keys) were identified as sinks that received migrants (and alleles) from other populations but failed to export individuals. These populations thus harbor genetic variation, perhaps even from extirpated populations across the range, but ocean currents and complex arrangements of landmasses might prevent the distribution of that genetic variation elsewhere. Hence, the inherent asymmetry of ocean currents shown to impact both genetic differentiation and directional migration rates may be responsible for the complex distribution of genetic variation across the range and observed patterns of metapopulation structure.
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Affiliation(s)
- Anthony A. Snead
- Department of Biological Sciences, University of Alabama, Tuscaloosa, AL, United States
| | - Andrey Tatarenkov
- Department of Ecology and Evolutionary Biology, University of California, Irvine, Irvine, CA, United States
| | - John C. Avise
- Department of Ecology and Evolutionary Biology, University of California, Irvine, Irvine, CA, United States
| | | | - Bruce J. Turner
- Department of Biological Sciences, Virginia Tech, Blacksburg, VA, United States
| | - Kristine Marson
- Department of Biological Sciences, University of Alabama, Tuscaloosa, AL, United States
| | - Ryan L. Earley
- Department of Biological Sciences, University of Alabama, Tuscaloosa, AL, United States
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2
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Rossi GS, Wright PA. Does leaving water make fish smarter? Terrestrial exposure and exercise improve spatial learning in an amphibious fish. Proc Biol Sci 2021; 288:20210603. [PMID: 34130503 DOI: 10.1098/rspb.2021.0603] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
Amphibious fishes transition between aquatic and terrestrial habitats, and must therefore learn to navigate two dramatically different environments. We used the amphibious killifish Kryptolebias marmoratus to test the hypothesis that the spatial learning ability of amphibious fishes would be altered by exposure to terrestrial environments because of neural plasticity in the brain region linked to spatial cognition (dorsolateral pallium). We subjected fish to eight weeks of fluctuating air-water conditions or terrestrial exercise before assessing spatial learning using a bifurcating T-maze, and neurogenesis in the dorsolateral pallium by immunostaining for proliferating cell nuclear antigen. In support of our hypothesis, we found that air-water fluctuations and terrestrial exercise improved some markers of spatial learning. Moreover, air-water and exercised fish had 39% and 46% more proliferating cells in their dorsolateral pallium relative to control fish, respectively. Overall, our findings suggest that fish with more terrestrial tendencies may have a cognitive advantage over those that remain in water, which ultimately may influence their fitness in both aquatic and terrestrial settings. More broadly, understanding the factors that promote neural and behavioural plasticity in extant amphibious fishes may provide insights into how ancestral fishes successfully colonized novel terrestrial environments before giving rise to land-dwelling tetrapods.
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Affiliation(s)
- Giulia S Rossi
- Department of Integrative Biology, University of Guelph, Guelph, Ontario, Canada N1G 2W1
| | - Patricia A Wright
- Department of Integrative Biology, University of Guelph, Guelph, Ontario, Canada N1G 2W1
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3
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Cochrane PV, Jonz MG, Wright PA. The development of the O 2-sensing system in an amphibious fish: consequences of variation in environmental O 2 levels. J Comp Physiol B 2021; 191:681-699. [PMID: 34023926 DOI: 10.1007/s00360-021-01379-5] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2021] [Revised: 03/04/2021] [Accepted: 05/07/2021] [Indexed: 11/25/2022]
Abstract
Proper development of the O2-sensing system is essential for survival. Here, we characterized the development of the O2-sensing system in the mangrove rivulus (Kryptolebias marmoratus), an amphibious fish that transitions between hypoxic aquatic environments and O2-rich terrestrial environments. We found that NECs formed in the gills and skin of K. marmoratus during embryonic development and that both NEC populations are retained from the embryonic stage to adulthood. We also found that the hyperventilatory response to acute hypoxia was present in embryonic K. marmoratus, indicating that functional O2-sensing pathways are formed during embryonic development. We then exposed embryos to aquatic normoxia, aquatic hyperoxia, aquatic hypoxia, or terrestrial conditions for the first 30 days of embryonic development and tested the hypothesis that environmental O2 availability during embryonic development modulates the development of the O2-sensing system in amphibious fishes. Surprisingly, we found that O2 availability during embryonic development had little impact on the density and morphology of NECs in the gills and skin of K. marmoratus. Collectively, our results demonstrate that, unlike the only other species of fish in which NEC development has been studied to date (i.e., zebrafish), NEC development in K. marmoratus is largely unaffected by environmental O2 levels during the embryonic stage, indicating that there is interspecies variation in O2-induced plasticity in the O2-sensing system of fishes.
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Affiliation(s)
- Paige V Cochrane
- Department of Integrative Biology, University of Guelph, Guelph, ON, N1G 2W1, Canada.
| | - Michael G Jonz
- Department of Biology, University of Ottawa, Ottawa, ON, K1N 6N5, Canada
| | - Patricia A Wright
- Department of Integrative Biology, University of Guelph, Guelph, ON, N1G 2W1, Canada
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4
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Dong YW, Blanchard TS, Noll A, Vasquez P, Schmitz J, Kelly SP, Wright PA, Whitehead A. Genomic and physiological mechanisms underlying skin plasticity during water to air transition in an amphibious fish. J Exp Biol 2021; 224:jeb235515. [PMID: 33328287 PMCID: PMC7860121 DOI: 10.1242/jeb.235515] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2020] [Accepted: 12/09/2020] [Indexed: 12/24/2022]
Abstract
The terrestrial radiation of vertebrates required changes in skin that resolved the dual demands of maintaining a mechanical and physiological barrier while also facilitating ion and gas transport. Using the amphibious killifish Kryptolebias marmoratus, we found that transcriptional regulation of skin morphogenesis was quickly activated upon air exposure (1 h). Rapid regulation of cell-cell adhesion complexes and pathways that regulate stratum corneum formation was consistent with barrier function and mechanical reinforcement. Unique blood vessel architecture and regulation of angiogenesis likely supported cutaneous respiration. Differences in ionoregulatory transcripts and ionocyte morphology were correlated with differences in salinity acclimation and resilience to air exposure. Evolutionary analyses reinforced the adaptive importance of these mechanisms. We conclude that rapid plasticity of barrier, respiratory and ionoregulatory functions in skin evolved to support the amphibious lifestyle of K. marmoratus; similar processes may have facilitated the terrestrial radiation of other contemporary and ancient fishes.
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Affiliation(s)
- Yun-Wei Dong
- The Key Laboratory of Mariculture, Ministry of Education, Fisheries College, Ocean University of China, Qingdao, People's Republic of China
| | - Tessa S Blanchard
- Department of Integrative Biology, University of Guelph, Guelph, ON, Canada, N1G 2W1
| | - Angela Noll
- Primate Genetics Laboratory, German Primate Center (DPZ), Leibniz Institute for Primate Research, 37077 Göttingen, Germany
| | - Picasso Vasquez
- Department of Environmental Toxicology, University of California Davis, Davis, CA 95616, USA
| | - Juergen Schmitz
- Institute of Experimental Pathology, Center for Molecular Biology of Inflammation (ZMBE), University of Münster, 48149 Münster, Germany
| | - Scott P Kelly
- Department of Biology, York University, Toronto, ON, Canada, M3J 1P3
| | - Patricia A Wright
- Department of Integrative Biology, University of Guelph, Guelph, ON, Canada, N1G 2W1
| | - Andrew Whitehead
- Department of Environmental Toxicology, Center for Population Biology, Coastal and Marine Sciences Institute, University of California Davis, Davis, CA 95616, USA
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5
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Tunnah L, Robertson CE, Turko AJ, Wright PA. Acclimation to prolonged aquatic hypercarbia or air enhances hemoglobin‑oxygen affinity in an amphibious fish. Comp Biochem Physiol A Mol Integr Physiol 2020; 252:110848. [PMID: 33217558 DOI: 10.1016/j.cbpa.2020.110848] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2020] [Revised: 11/12/2020] [Accepted: 11/12/2020] [Indexed: 10/23/2022]
Abstract
When the amphibious mangrove rivulus (Kryptolebias marmoratus) leaves water for extended periods, hemoglobin-O2 binding affinity increases. We tested the hypothesis that the change in affinity was a consequence of hemoglobin isoform switching driven by exposure to environments associated with increased internal CO2 levels. We exposed K. marmoratus to either water (control, pH 8.1), air, aquatic hypercarbia (5.1 kPa CO2, pH 6.6-6.8), or aquatic acid (isocarbic control, pH 6.6-6.8), for 7 days, and measured hemoglobin-O2 affinity spectrophotometrically. We found that mangrove rivulus compensated for elevated CO2 and aquatic acid exposure by shifting hemoglobin-O2 affinity back to aquatic (control) levels when measured at an ecologically-relevant high CO2 level that would be experienced in vivo. Using proteomics, we found that the hemoglobin subunits present in the blood did not change between treatments, but air and aquatic acid exposure altered the abundance of cathodic hemoglobin subunits. We therefore conclude that hemoglobin isoform switching is not a primary strategy used by mangrove rivulus to adjust P50 under these conditions. Abundances of other RBC proteins also differed between treatment groups relative to control fish (e.g. Rhesus protein type A, band 3 anion exchanger). Overall, our data indicate that both aquatic hypercarbia and aquatic acidosis create similar changes in hemoglobin-O2 affinity as air exposure. However, the protein-level consequences differ between these groups, indicating that the red blood cell response of mangrove rivulus can be modulated depending on the environmental cue received.
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Affiliation(s)
- Louise Tunnah
- Department of Integrative Biology, University of Guelph, Guelph, Ontario N1G 2W1, Canada.
| | - Cayleih E Robertson
- Department of Integrative Biology, University of Guelph, Guelph, Ontario N1G 2W1, Canada; Department of Biology, McMaster University, Hamilton, Ontario L8S 4K1, Canada.
| | - Andy J Turko
- Department of Integrative Biology, University of Guelph, Guelph, Ontario N1G 2W1, Canada; Department of Biology, McMaster University, Hamilton, Ontario L8S 4K1, Canada; Great Lakes Institute for Environmental Research, University of Windsor, Windsor, ON N9B 3P4, Canada
| | - Patricia A Wright
- Department of Integrative Biology, University of Guelph, Guelph, Ontario N1G 2W1, Canada.
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Houpt N, Borowiec BG, Bose APH, Brown NAW, Scott GR, Balshine S. Parental Males of the Plainfin Midshipman Are Physiologically Resilient to the Challenges of the Intertidal Zone. Physiol Biochem Zool 2020; 93:111-128. [PMID: 32013739 DOI: 10.1086/707408] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
The decision of where to rear young is influenced by both the needs of offspring and the costs parents incur in certain rearing environments. Plainfin midshipman fish (Porichthys notatus) provide extended paternal care in rocky intertidal zones, where they experience regular bouts of aquatic hypoxia and air exposure during low-tide events. We investigated the physiological responses of plainfin midshipman males to three conditions for 6 h that simulate what these fish naturally experience during tidal cycles while nesting: normoxia, progressive hypoxia, or air exposure. Hypoxia- and air-exposed fish exhibited shifts in energy metabolites, driven largely by elevated lactate and glucose content and reduced glycogen content in several tissues (muscle, heart, liver, and brain), but the magnitude of these changes was relatively modest. Hematocrit increased most in air-exposed fish relative to normoxia-exposed fish, contributing to an increase in whole-blood hemoglobin concentration. Air exposure reduced swim bladder oxygen content, suggesting that internal O2 stores are drawn on during air exposure. In a second experiment, we found that aquatic surface respiration and gill ventilation frequency increased in hypoxia-exposed fish relative to normoxia-exposed fish. Overall, our results suggest that plainfin midshipman overcome the challenges of the intertidal environment through a variety of physiological strategies and exhibit little physiological disturbance in response to the fluctuating and extreme conditions created by regular low tides.
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Rossi GS, Cochrane PV, Wright PA. Fluctuating environments during early development can limit adult phenotypic flexibility: insights from an amphibious fish. J Exp Biol 2020; 223:jeb228304. [PMID: 32616545 DOI: 10.1242/jeb.228304] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2020] [Accepted: 06/29/2020] [Indexed: 12/11/2022]
Abstract
The interaction between developmental plasticity and the capacity for reversible acclimation (phenotypic flexibility) is poorly understood, particularly in organisms exposed to fluctuating environments. We used an amphibious killifish (Kryptolebias marmoratus) to test the hypotheses that organisms reared in fluctuating environments (i) will make no developmental changes to suit any one environment because fixing traits to suit one environment could be maladaptive for another, and (ii) will be highly phenotypically flexible as adults because their early life experiences predict high environmental variability in the future. We reared fish under constant (water) or fluctuating (water-air) environments until adulthood and assessed a suite of traits along the oxygen cascade (e.g. neuroepithelial cell density and size, cutaneous capillarity, gill morphology, ventricle size, red muscle morphometrics, terrestrial locomotor performance). To evaluate the capacity for phenotypic flexibility, a subset of adult fish from each rearing condition was then air-exposed for 14 days before the same traits were measured. In support of the developmental plasticity hypothesis, traits involved with O2 sensing and uptake were largely unaffected by water-air fluctuations during early life, but we found marked developmental changes in traits related to O2 transport, utilization and locomotor performance. In contrast, we found no evidence supporting the phenotypic flexibility hypothesis. Adult fish from both rearing conditions exhibited the same degree of phenotypic flexibility in various O2 sensing- and uptake-related traits. In other cases, water-air fluctuations attenuated adult phenotypic flexibility despite the fact that phenotypic flexibility is hypothesized to be favoured when environments fluctuate. Overall, we conclude that exposure to environmental fluctuations during development in K. marmoratus can dramatically alter the constitutive adult phenotype, as well as diminish the scope for phenotypic flexibility in later life.
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Affiliation(s)
- Giulia S Rossi
- Department of Integrative Biology, University of Guelph, Guelph, ON, Canada N1G 2W1
| | - Paige V Cochrane
- Department of Integrative Biology, University of Guelph, Guelph, ON, Canada N1G 2W1
| | - Patricia A Wright
- Department of Integrative Biology, University of Guelph, Guelph, ON, Canada N1G 2W1
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8
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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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9
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Rossi GS, Cochrane PV, Tunnah L, Wright PA. Ageing impacts phenotypic flexibility in an air-acclimated amphibious fish. J Comp Physiol B 2019; 189:567-579. [PMID: 31520114 DOI: 10.1007/s00360-019-01234-8] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2019] [Revised: 07/24/2019] [Accepted: 08/21/2019] [Indexed: 12/11/2022]
Abstract
The ability to tolerate environmental change may decline as fishes age. We tested the hypothesis that ageing influences the scope for phenotypic flexibility in the mangrove rivulus (Kryptolebias marmoratus), an amphibious fish that transitions between two vastly different environments, water and land. We found that older fish (4-6 years old) exhibited marked signs of ageing; older fish were reproductively senescent, had reduced fin regenerative capacity and body condition, and exhibited atrophy of both oxidative and glycolytic muscle fibers relative to younger adult fish (1-2 years old). However, age did not affect routine O2 consumption. We then acclimated adult fish (1-6 years) to water (control) or air for 10 days to assess the scope for phenotypic flexibility in response to terrestrial exposure. In support of our hypothesis, we found that older air-acclimated fish had a diminished scope for gill remodeling relative to younger fish. We also found that older fish exhibited poorer terrestrial locomotor performance relative to younger adult fish, particularly when acclimated to air. Our results indicate that ageing diminishes skeletal muscle integrity and locomotor performance of amphibious fishes, and may, therefore, impair terrestrial foraging ability, predator avoidance, or dispersal across the terrestrial environment. Remarkably, older fish voluntarily left water to a similar degree as younger fish despite the age-related deterioration of traits important for terrestrial life.
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Affiliation(s)
- Giulia S Rossi
- Department of Integrative Biology, University of Guelph, Guelph, ON, N1G 2W1, Canada
| | - Paige V Cochrane
- Department of Integrative Biology, University of Guelph, Guelph, ON, N1G 2W1, Canada
| | - Louise Tunnah
- 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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10
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Turko AJ, Maini P, Wright PA, Standen EM. Gill remodelling during terrestrial acclimation in the amphibious fish Polypterus senegalus. J Morphol 2019; 280:329-338. [PMID: 30707482 DOI: 10.1002/jmor.20946] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2018] [Revised: 12/12/2018] [Accepted: 12/19/2018] [Indexed: 12/19/2022]
Abstract
Fishes are effectively weightless in water due to the buoyant support of the environment, but amphibious fishes must cope with increased effective weight when on land. Delicate structures such as gills are especially vulnerable to collapse and loss of surface area out of water. We tested the 'structural support' hypothesis that amphibious Polypterus senegalus solve this problem using phenotypically plastic changes that provide mechanical support and increase stiffness at the level of the gill lamellae, the filaments, and the whole arches. After 7 d in terrestrial conditions, enlargement of an inter-lamellar cell mass filled the water channels between gill lamellae, possibly to provide structural support and/or reduce evaporative water loss. Similar gill remodelling has been described in several other actinopterygian fishes, suggesting this may be an ancestral trait. There was no change in the mechanical properties or collagen composition of filaments or arches after 7 days out of water, but 8 months of terrestrial acclimation caused a reduction in gill arch length and mineralized bone volume. Thus, rather than increasing the size and stiffness of the gill skeleton, P. senegalus may instead reduce investment in supportive gill tissue while on land. These results are strikingly similar to the evolutionary trend of gill loss that occurred during the tetrapod invasion of land, raising the possibility that genetic assimilation of gill plasticity was an underlying mechanism.
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Affiliation(s)
- Andy J Turko
- Department of Integrative Biology, University of Guelph, Guelph, Ontario, Canada
| | - Priyam Maini
- Department of Biology, University of Ottawa, Ottawa, Ontario, Canada
| | - Patricia A Wright
- Department of Integrative Biology, University of Guelph, Guelph, Ontario, Canada
| | - Emily M Standen
- Department of Biology, University of Ottawa, Ottawa, Ontario, Canada
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11
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Blanchard TS, Whitehead A, Dong YW, Wright PA. Phenotypic flexibility in respiratory traits is associated with improved aerial respiration in an amphibious fish out of water. ACTA ACUST UNITED AC 2019; 222:jeb.186486. [PMID: 30446543 DOI: 10.1242/jeb.186486] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2018] [Accepted: 11/14/2018] [Indexed: 01/17/2023]
Abstract
Amphibious fishes have evolved multiple adaptive strategies for respiring out of water, but there has been less focus on reversible plasticity. We tested the hypothesis that when amphibious fishes leave water, enhanced respiratory performance on land is the result of rapid functional phenotypic flexibility of respiratory traits. We acclimated four isogenic strains of Kryptolebias marmoratus to air for 0, 1, 3 or 7 days. We compared respiratory performance out of water with traits linked to the O2 cascade. Aerial O2 consumption rate was measured over a step-wise decrease in O2 levels. There were significant differences between strains, but time out of water had the largest impact on measured parameters. K ryptolebias marmoratus had improved respiratory performance [lower aerial critical oxygen tension (P crit), higher regulation index (RI)] after only 1 day of air exposure, and these changes were strongly associated with the change in hematocrit and dorsal cutaneous angiogenesis. Additionally, we found that 1 h of air exposure induced the expression of four angiogenesis-associated genes - vegfa, angpt2, pecam-1 and efna1 - in the skin. After 7 days in air, respiratory traits were not significantly linked to the variation in either aerial P crit or RI. Overall, our data indicate that there are two phases involved in the enhancement of aerial respiration: an initial rapid response (1 day) and a delayed response (7 days). We found evidence for the hypothesis that respiratory performance on land in amphibious fishes is the result of rapid flexibility in both O2 uptake and O2 carrying capacity.
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Affiliation(s)
- Tessa S Blanchard
- Department of Integrative Biology, University of Guelph, Guelph, ON, Canada, N1G 2W1
| | - Andrew Whitehead
- Department of Environmental Toxicology, University of California Davis, Davis, CA 95616, USA
| | - Yunwei W Dong
- Department of Environmental Toxicology, University of California Davis, Davis, CA 95616, USA.,State Key Laboratory of Marine Environmental Science, College of Ocean and Earth Sciences, Xiamen 361102, People's Republic of China
| | - Patricia A Wright
- Department of Integrative Biology, University of Guelph, Guelph, ON, Canada, N1G 2W1
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12
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Turko AJ, Doherty JE, Yin-Liao I, Levesque K, Kruth P, Holden JM, Earley RL, Wright PA. Prolonged survival out of water is linked to a slow pace of life in a selfing amphibious fish. J Exp Biol 2019; 222:jeb.209270. [DOI: 10.1242/jeb.209270] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2019] [Accepted: 11/25/2019] [Indexed: 12/25/2022]
Abstract
Metabolic rate and life history traits vary widely both among and within species reflecting trade-offs in energy allocation, but the proximate and ultimate causes of variation are not well understood. We tested the hypothesis that these trade-offs are mediated by environmental heterogeneity, using isogenic strains of the amphibious fish Kryptolebias marmoratus that vary in the amount of time each can survive out of water. Consistent with pace of life theory, the strain that survived air exposure the longest generally exhibited a “slow” phenotype including the lowest metabolic rate, largest scope for metabolic depression, slowest consumption of energy stores, and least investment in reproduction under standard conditions. Growth rates were fastest in the otherwise “slow” strain, however. We then tested for fitness trade-offs between “fast” and “slow” strains using microcosms where fish were held with either constant water availability or under fluctuating conditions where water was absent for half of the experiment. Under both conditions the “slow” strain grew larger and was in better condition, and under fluctuating conditions the “slow” strain produced more embryos. However, the “fast” strain had larger adult population sizes under both conditions, indicating that fecundity is not the sole determinant of population size in this species. We conclude that genetically based differences in pace of life of amphibious fish determine survival duration out of water. Relatively “slow” fish tended to perform better under conditions of limited water availability, but there was no detectable cost under control conditions. Thus, pace of life differences may reflect a conditionally neutral instead of antagonistic trade-off.
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Affiliation(s)
- Andy J. Turko
- Department of Integrative Biology, University of Guelph, Guelph, ON, Canada, N1G 2W1
| | - Justine E. Doherty
- Department of Integrative Biology, University of Guelph, Guelph, ON, Canada, N1G 2W1
| | - Irene Yin-Liao
- Department of Integrative Biology, University of Guelph, Guelph, ON, Canada, N1G 2W1
| | - Kelly Levesque
- Department of Integrative Biology, University of Guelph, Guelph, ON, Canada, N1G 2W1
| | - Perryn Kruth
- Department of Integrative Biology, University of Guelph, Guelph, ON, Canada, N1G 2W1
| | - Joseph M. Holden
- Department of Biological Sciences, University of Alabama, Tuscaloosa, AL, USA, 35487
| | - Ryan L. Earley
- Department of Biological Sciences, University of Alabama, Tuscaloosa, AL, USA, 35487
| | - Patricia A. Wright
- Department of Integrative Biology, University of Guelph, Guelph, ON, Canada, N1G 2W1
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13
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Martin KE, Ehrman JM, Wilson JM, Wright PA, Currie S. Skin ionocyte remodeling in the amphibious mangrove rivulus fish (Kryptolebias marmoratus
). JOURNAL OF EXPERIMENTAL ZOOLOGY PART 2018; 331:128-138. [DOI: 10.1002/jez.2247] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/22/2018] [Revised: 10/24/2018] [Accepted: 10/25/2018] [Indexed: 12/19/2022]
Affiliation(s)
- Keri E. Martin
- Department of Biology, Mount Allison University; Sackville New Brunswick Canada
| | - James M. Ehrman
- Department of Biology, Mount Allison University; Sackville New Brunswick Canada
| | - Jonathan M. Wilson
- Department of Biology, Wilfrid Laurier University; Waterloo Ontario Canada
| | - Patricia A. Wright
- Department of Integrative Biology, University of Guelph; Guelph Ontario Canada
| | - Suzanne Currie
- Department of Biology, Mount Allison University; Sackville New Brunswick Canada
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14
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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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15
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Turko AJ, Kültz D, Fudge D, Croll RP, Smith FM, Stoyek MR, Wright PA. Skeletal stiffening in an amphibious fish out of water is a response to increased body weight. ACTA ACUST UNITED AC 2018; 220:3621-3631. [PMID: 29046415 DOI: 10.1242/jeb.161638] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2017] [Accepted: 08/07/2017] [Indexed: 01/06/2023]
Abstract
Terrestrial animals must support their bodies against gravity, while aquatic animals are effectively weightless because of buoyant support from water. Given this evolutionary history of minimal gravitational loading of fishes in water, it has been hypothesized that weight-responsive musculoskeletal systems evolved during the tetrapod invasion of land and are thus absent in fishes. Amphibious fishes, however, experience increased effective weight when out of water - are these fishes responsive to gravitational loading? Contrary to the tetrapod-origin hypothesis, we found that terrestrial acclimation reversibly increased gill arch stiffness (∼60% increase) in the amphibious fish Kryptolebias marmoratus when loaded normally by gravity, but not under simulated microgravity. Quantitative proteomics analysis revealed that this change in mechanical properties occurred via increased abundance of proteins responsible for bone mineralization in other fishes as well as in tetrapods. Type X collagen, associated with endochondral bone growth, increased in abundance almost ninefold after terrestrial acclimation. Collagen isoforms known to promote extracellular matrix cross-linking and cause tissue stiffening, such as types IX and XII collagen, also increased in abundance. Finally, more densely packed collagen fibrils in both gill arches and filaments were observed microscopically in terrestrially acclimated fish. Our results demonstrate that the mechanical properties of the fish musculoskeletal system can be fine-tuned in response to changes in effective body weight using biochemical pathways similar to those in mammals, suggesting that weight sensing is an ancestral vertebrate trait rather than a tetrapod innovation.
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Affiliation(s)
- Andy J Turko
- Department of Integrative Biology, University of Guelph, 50 Stone Road East, Guelph, ON, Canada N1G 2W1
| | - Dietmar Kültz
- Department of Animal Sciences, University of California, Davis, 1 Shields Ave., Meyer Hall, Davis, CA 95616, USA
| | - Douglas Fudge
- Department of Integrative Biology, University of Guelph, 50 Stone Road East, Guelph, ON, Canada N1G 2W1.,Schmid College of Science and Technology, Chapman University, 1 University Dr., Orange, CA 92866, USA
| | - Roger P Croll
- Department of Physiology and Biophysics, Dalhousie University, 5850 College Street, Halifax, Nova Scotia, Canada B3H 4R2
| | - Frank M Smith
- Department of Medical Neuroscience, Dalhousie University, 5850 College Street, Halifax, Nova Scotia, Canada B3H 4R2
| | - Matthew R Stoyek
- Department of Physiology and Biophysics, Dalhousie University, 5850 College Street, Halifax, Nova Scotia, Canada B3H 4R2.,Department of Medical Neuroscience, Dalhousie University, 5850 College Street, Halifax, Nova Scotia, Canada B3H 4R2
| | - Patricia A Wright
- Department of Integrative Biology, University of Guelph, 50 Stone Road East, Guelph, ON, Canada N1G 2W1
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16
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Turko AJ, Tatarenkov A, Currie S, Earley RL, Platek A, Taylor DS, Wright PA. Emersion behaviour underlies variation in gill morphology and aquatic respiratory function in the amphibious fish Kryptolebias marmoratus. ACTA ACUST UNITED AC 2018; 221:jeb.168039. [PMID: 29511069 DOI: 10.1242/jeb.168039] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2017] [Accepted: 03/01/2018] [Indexed: 12/21/2022]
Abstract
Fishes acclimated to hypoxic environments often increase gill surface area to improve O2 uptake. In some species, surface area is increased via reduction of an interlamellar cell mass (ILCM) that fills water channels between gill lamellae. Amphibious fishes, however, may not increase gill surface area in hypoxic water because these species can, instead, leave water and breathe air. To differentiate between these possibilities, we compared wild amphibious mangrove rivulus Kryptolebias marmoratus from two habitats that varied in O2 availability - a hypoxic freshwater pool versus nearly anoxic crab burrows. Fish captured from crab burrows had less gill surface area (as ILCMs were enlarged by ∼32%), increased rates of normoxic O2 consumption and increased critical O2 tension compared with fish from the freshwater pool. Thus, wild mangrove rivulus do not respond to near-anoxic water by decreasing metabolism or increasing O2 extraction. Instead, fish from the crab burrow habitat spent three times longer out of water, which probably caused the observed changes in gill morphology and respiratory phenotype. We also tested whether critical O2 tension is influenced by genetic heterozygosity, as K. marmoratus is one of only two hermaphroditic vertebrate species that can produce both self-fertilized (inbred) or out-crossed (more heterozygous) offspring. We found no evidence for inbreeding depression, suggesting that self-fertilization does not impair respiratory function. Overall, our results demonstrate that amphibious fishes that inhabit hypoxic aquatic habitats can use a fundamentally different strategy from that used by fully aquatic water-breathing fishes, relying on escape behaviour rather than metabolic depression or increased O2 extraction ability.
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Affiliation(s)
- A J Turko
- Department of Integrative Biology, University of Guelph, Guelph, Ontario, Canada N1G 2W1
| | - A Tatarenkov
- Department of Ecology and Evolutionary Biology, University of California, Irvine, Irvine, CA 92697, USA
| | - S Currie
- Department of Biology, Mount Allison University, Sackville, New Brunswick, Canada E4L 1E2
| | - R L Earley
- Department of Biological Sciences, University of Alabama, Tuscaloosa, AL 35487, USA
| | - A Platek
- Department of Integrative Biology, University of Guelph, Guelph, Ontario, Canada N1G 2W1
| | - D S Taylor
- Brevard County Environmentally Endangered Lands Program, Melbourne, FL 32904, USA
| | - P A Wright
- Department of Integrative Biology, University of Guelph, Guelph, Ontario, Canada N1G 2W1
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17
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Intraspecific variation and plasticity in mitochondrial oxygen binding affinity as a response to environmental temperature. Sci Rep 2017; 7:16238. [PMID: 29176558 PMCID: PMC5701142 DOI: 10.1038/s41598-017-16598-6] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2017] [Accepted: 11/15/2017] [Indexed: 01/19/2023] Open
Abstract
Mitochondrial function has been suggested to underlie constraints on whole-organism aerobic performance and associated hypoxia and thermal tolerance limits, but most studies have focused on measures of maximum mitochondrial capacity. Here we investigated whether variation in mitochondrial oxygen kinetics could contribute to local adaptation and plasticity in response to temperature using two subspecies of the Atlantic killifish (Fundulus heteroclitus) acclimated to a range of temperatures (5, 15, and 33 °C). The southern subspecies of F. heteroclitus, which has superior thermal and hypoxia tolerances compared to the northern subspecies, exhibited lower mitochondrial O2 P50 (higher O2 affinity). Acclimation to thermal extremes (5 or 33 °C) altered mitochondrial O2 P50 in both subspecies consistent with the effects of thermal acclimation on whole-organism thermal tolerance limits. We also examined differences between subspecies and thermal acclimation effects on whole-blood Hb O2-P50 to assess whether variation in oxygen delivery is involved in these responses. In contrast to the clear differences between subspecies in mitochondrial O2-P50 there were no differences in whole-blood Hb-O2 P50 between subspecies. Taken together these findings support a general role for mitochondrial oxygen kinetics in differentiating whole-organism aerobic performance and thus in influencing species responses to environmental change.
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18
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Thompson AW, Hayes A, Podrabsky JE, Ortí G. Gene expression during delayed hatching in fish-out-of-water. ACTA ACUST UNITED AC 2017. [DOI: 10.1016/j.egg.2017.09.002] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
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19
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Heffell Q, Turko AJ, Wright PA. Plasticity of skin water permeability and skin thickness in the amphibious mangrove rivulus Kryptolebias marmoratus. J Comp Physiol B 2017; 188:305-314. [PMID: 28940028 DOI: 10.1007/s00360-017-1123-4] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2017] [Revised: 08/29/2017] [Accepted: 09/11/2017] [Indexed: 01/29/2023]
Abstract
The skin of amphibious fishes is a multipurpose organ, important for gas and ion exchange and nitrogen excretion when fish are out of water (emersed). We tested the hypothesis that skin permeability is altered to maintain water balance through changes in water permeability and skin thickness during salinity acclimation and/or when fish emerse, using the euryhaline, amphibious fish Kryptolebias marmoratus as a model. We first recorded the behaviour of fish out of water to determine which part of the cutaneous surface was in contact with the substrate. Fish spent about 70% of their time on their ventral surface when out of water. Osmotic permeability of the skin was assessed in fish acclimated to 0.3 or 45‰ using 3H2O fluxes in an in vitro micro-Ussing chamber setup. In freshwater-acclimated fish, 3H2O influx across the skin was significantly higher compared to hypersaline-acclimated fish, with no significant changes in efflux. Prolonged emersion (7 days) resulted in an increase in skin 3H2O influx, but not efflux in fish acclimated to a moist 45‰ substrate. In a separate experiment, dorsal epidermal skin thickness increased while the ventral dermis thickness decreased in fish emersed for over a week. However, there was no link between regional skin thickness and water flux in our experiments. Taken together, these findings suggest that K. marmoratus alter skin permeability to maximize water uptake while emersed in hypersaline conditions, adjustments that probably help them survive months of emersion during the dry season when drinking to replace water loss is not possible.
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Affiliation(s)
- Quentin Heffell
- Department of Integrative Biology, University of Guelph, Guelph, ON, N1G 2W1, Canada
| | - Andy J Turko
- 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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20
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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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21
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Blewett TA, Simon RA, Turko AJ, Wright PA. Copper alters hypoxia sensitivity and the behavioural emersion response in the amphibious fish Kryptolebias marmoratus. AQUATIC TOXICOLOGY (AMSTERDAM, NETHERLANDS) 2017; 189:25-30. [PMID: 28575749 DOI: 10.1016/j.aquatox.2017.05.007] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/18/2017] [Revised: 05/03/2017] [Accepted: 05/16/2017] [Indexed: 06/07/2023]
Abstract
Elevated levels of metals have been reported in mangrove ecosystems worldwide. Mangrove fishes also routinely experience severe environmental stressors, such as hypoxia. In the amphibious fish Kryptolebias marmoratus (mangrove rivulus), a key behavioural response to avoid aquatic stress is to leave water (emersion). We hypothesized that copper (Cu) exposure would increase the sensitivity of this behavioural hypoxia avoidance response due to histopathological effects of Cu on gill structure and function. K. marmoratus were exposed to either control (no added Cu) or Cu (300μg/L) for 96h. Following this period, fish were exposed to an acute hypoxic challenge (decline in dissolved oxygen to ∼0% over 15min), and the emersion response was recorded. Gills were examined for histological changes. Fish exposed to Cu emersed at a higher dissolved oxygen level (7.5±0.6%), relative to the control treatment group (5.8±0.4%). Histological analysis showed that the gill surface area increased and the interlamellar cell mass (ILCM) was reduced following Cu exposure, contrary to our prediction. Overall, these data indicate that Cu induces hypoxia-like changes to gill morphology and increases the sensitivity of the hypoxia emersion response.
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Affiliation(s)
- Tamzin A Blewett
- Department of Chemistry and Biochemistry, Wilfrid Laurier University, Waterloo, Ontario, N2L 3C5, Canada.
| | - Robyn A Simon
- Department of Integrative Biology, University of Guelph, 50 Stone Road East, Guelph, Ontario, N1G 2W1, Canada
| | - Andy J Turko
- Department of Integrative Biology, University of Guelph, 50 Stone Road East, Guelph, Ontario, N1G 2W1, Canada
| | - Patricia A Wright
- Department of Integrative Biology, University of Guelph, 50 Stone Road East, Guelph, Ontario, N1G 2W1, Canada
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22
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Platek A, Turko AJ, Donini A, Kelly S, Wright PA. Environmental calcium regulates gill remodeling in a euryhaline teleost fish. JOURNAL OF EXPERIMENTAL ZOOLOGY PART 2017; 327:139-142. [PMID: 29356395 DOI: 10.1002/jez.2079] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/09/2017] [Accepted: 06/12/2017] [Indexed: 11/12/2022]
Abstract
Some cyprindid and cyprinidontiform fishes undergo gill remodeling via the proliferation or regression of an interlamellar cell mass (ILCM), resulting in the modification of gill surface area in response to environmental hypoxia or ion levels. We hypothesized that ion-related gill remodeling is regulated by water hardness through the interactions of Ca2+ with tight junctions, predicting that gills will exhibit a lower ILCM and more surface area in a high Ca2+ environment than in a low Ca2+ environment. To test this hypothesis, we acclimated euryhaline mangrove rivulus (Kryptolebias marmoratus) to natural hard water ([Ca2+] = 2.77 mmol/L), low Ca2+ ([Ca2+] = 0.13 mmol/L) freshwater, or high Ca2+ water (5.88 mmol/L). Fish exposed to hard water had a significantly lower ILCM height than fish exposed to low Ca2+ water. The addition of Ca2+ to low Ca2+ water restored gill surface area. Plasma Ca2+ activity was not significantly different between groups. This study provides support for an influence of external Ca2+ on gill remodeling and represents the first evidence of an ionic trigger (Ca2+) for gill remodeling in teleost fishes.
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Affiliation(s)
- Alexis Platek
- Department of Integrative Biology, University of Guelph, Guelph, Ontario, Canada
| | - Andy J Turko
- Department of Integrative Biology, University of Guelph, Guelph, Ontario, Canada
| | - Andrew Donini
- Department of Biology, York University, Toronto, Ontario, Canada
| | - Scott Kelly
- Department of Biology, York University, Toronto, Ontario, Canada
| | - Patricia A Wright
- Department of Integrative Biology, University of Guelph, Guelph, Ontario, Canada
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23
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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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24
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Sun S, Xuan F, Fu H, Zhu J, Ge X, Wu X. Molecular cloning, mRNA expression and characterization of membrane-bound hemoglobin in oriental river prawn Macrobrachium nipponense. Comp Biochem Physiol A Mol Integr Physiol 2017; 207:36-42. [DOI: 10.1016/j.cbpa.2017.02.010] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2016] [Revised: 02/08/2017] [Accepted: 02/08/2017] [Indexed: 11/15/2022]
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25
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Brunt EM, Turko AJ, Scott GR, Wright PA. Amphibious fish jump better on land after acclimation to a terrestrial environment. ACTA ACUST UNITED AC 2016; 219:3204-3207. [PMID: 27591317 DOI: 10.1242/jeb.140970] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2016] [Accepted: 08/14/2016] [Indexed: 01/10/2023]
Abstract
Air and water differ dramatically in density and viscosity, posing different biomechanical challenges for animal locomotion. We asked how terrestrial acclimation influences locomotion in amphibious fish, specifically testing the hypothesis that terrestrial tail flip performance is improved by plastic changes in the skeletal muscle. Mangrove rivulus Kryptolebias marmoratus, which remain largely inactive out of water, were exposed to water or air for 14 days and a subgroup of air-exposed fish was also recovered in water. Tail flip jumping performance on land improved dramatically in air-acclimated fish, they had lower lactate levels compared with control fish, and these effects were mostly reversible. Muscle plasticity significantly increased oxidative muscle cross-sectional area and fibre size, as well as the number of capillaries per fibre. Our results show that reversible changes to the oxidative skeletal muscle of K. marmoratus out of water enhance terrestrial locomotory performance, even in the absence of exercise training.
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Affiliation(s)
- Emily M Brunt
- Department of Integrative Biology, University of Guelph, Guelph, ON, Canada N1G2W1
| | - Andy J Turko
- Department of Integrative Biology, University of Guelph, Guelph, ON, Canada N1G2W1
| | - Graham R Scott
- Department of Biology, McMaster University, Hamilton, ON, Canada L8S4K1
| | - Patricia A Wright
- Department of Integrative Biology, University of Guelph, Guelph, ON, Canada N1G2W1
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26
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Kelley JL, Yee MC, Brown AP, Richardson RR, Tatarenkov A, Lee CC, Harkins TT, Bustamante CD, Earley RL. The Genome of the Self-Fertilizing Mangrove Rivulus Fish, Kryptolebias marmoratus: A Model for Studying Phenotypic Plasticity and Adaptations to Extreme Environments. Genome Biol Evol 2016; 8:2145-54. [PMID: 27324916 PMCID: PMC4987111 DOI: 10.1093/gbe/evw145] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
The mangrove rivulus (Kryptolebias marmoratus) is one of two preferentially self-fertilizing hermaphroditic vertebrates. This mode of reproduction makes mangrove rivulus an important model for evolutionary and biomedical studies because long periods of self-fertilization result in naturally homozygous genotypes that can produce isogenic lineages without significant limitations associated with inbreeding depression. Over 400 isogenic lineages currently held in laboratories across the globe show considerable among-lineage variation in physiology, behavior, and life history traits that is maintained under common garden conditions. Temperature mediates the development of primary males and also sex change between hermaphrodites and secondary males, which makes the system ideal for the study of sex determination and sexual plasticity. Mangrove rivulus also exhibit remarkable adaptations to living in extreme environments, and the system has great promise to shed light on the evolution of terrestrial locomotion, aerial respiration, and broad tolerances to hypoxia, salinity, temperature, and environmental pollutants. Genome assembly of the mangrove rivulus allows the study of genes and gene families associated with the traits described above. Here we present a de novo assembled reference genome for the mangrove rivulus, with an approximately 900 Mb genome, including 27,328 annotated, predicted, protein-coding genes. Moreover, we are able to place more than 50% of the assembled genome onto a recently published linkage map. The genome provides an important addition to the linkage map and transcriptomic tools recently developed for this species that together provide critical resources for epigenetic, transcriptomic, and proteomic analyses. Moreover, the genome will serve as the foundation for addressing key questions in behavior, physiology, toxicology, and evolutionary biology.
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Affiliation(s)
- Joanna L Kelley
- School of Biological Sciences and Center for Reproductive Biology, Washington State University, Pullman, Washington
| | - Muh-Ching Yee
- Department of Plant Biology, Carnegie Institution for Science, Stanford, California
| | - Anthony P Brown
- School of Biological Sciences and Center for Reproductive Biology, Washington State University, Pullman, Washington
| | | | - Andrey Tatarenkov
- Department of Ecology and Evolutionary Biology, University of California, Irvine, California
| | | | | | | | - Ryan L Earley
- Department of Biological Sciences, University of Alabama, Tuscaloosa, Alabama
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27
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Regan MD, Gill I, Richards JG. Calorespirometry reveals that goldfish prioritize aerobic metabolism over metabolic rate depression in all but near-anoxic environments. J Exp Biol 2016; 220:564-572. [DOI: 10.1242/jeb.145169] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2016] [Accepted: 11/21/2016] [Indexed: 10/20/2022]
Abstract
Metabolic rate depression (MRD) has long been proposed as the key metabolic strategy of hypoxic survival, but surprisingly the effects of changes in hypoxic O2 tensions (PwO2) on MRD are largely unexplored. We simultaneously measured the O2 consumption rate (ṀO2) and metabolic heat of goldfish using calorespirometry to test the hypothesis that MRD is employed at hypoxic PwO2s and initiated just below Pcrit, the PwO2 below which ṀO2 is forced to progressively decline as the fish oxyconforms to decreasing PwO2. Specifically, we used closed-chamber and flow-through calorespirometry together with terminal sampling experiments to examine the effects of PwO2 and time on ṀO2, metabolic heat and anaerobic metabolism (lactate and ethanol production). The closed-chamber and flow-through experiments yielded slightly different results. Under closed-chamber conditions with a continually decreasing PwO2, goldfish showed a Pcrit of 3.0±0.3 kPa and metabolic heat production was only depressed at PwO2 between 0 and 0.67 kPa. Under flow-through conditions with PwO2 held at a variety of oxygen tensions for 1 and 4 h, goldfish also initiated MRD between 0 and 0.67 kPa but maintained ṀO2 to 0.67 kPa, indicating that Pcrit is at or below this PwO2. Anaerobic metabolism was strongly activated at PwO2 ≤1.3 kPa, but only used within the first hour at 1.3 and 0.67 kPa as anaerobic end-products did not accumulate between 1 and 4 h exposure. Taken together, it appears that goldfish reserve MRD for near-anoxia, supporting routine metabolic rate at sub-Pcrit PwO2s with the help of anaerobic glycolysis in the closed-chamber experiments, and aerobically after an initial (<1 h) activation of anaerobic metabolism in the flow-through experiments, even at 0.67 kPa PwO2.
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Affiliation(s)
- Matthew D. Regan
- Department of Zoology, University of British Columbia, 6270 University Blvd., Vancouver, BC V6T 1Z4, Canada
| | - Ivan Gill
- Department of Zoology, University of British Columbia, 6270 University Blvd., Vancouver, BC V6T 1Z4, Canada
| | - Jeffrey G. Richards
- Department of Zoology, University of British Columbia, 6270 University Blvd., Vancouver, BC V6T 1Z4, Canada
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28
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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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