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Wu S, Huang J, Li Y. A novel hypoxic lncRNA, LOC110520012 sponges miR-206-y to regulate angiogenesis and liver cell proliferation in rainbow trout (Oncorhynchus mykiss) by targeting vegfaa. ECOTOXICOLOGY AND ENVIRONMENTAL SAFETY 2024; 280:116554. [PMID: 38878335 DOI: 10.1016/j.ecoenv.2024.116554] [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: 01/15/2024] [Revised: 05/28/2024] [Accepted: 06/04/2024] [Indexed: 06/25/2024]
Abstract
Long non-coding RNA (lncRNA) is a novel emerging type of competitive endogenous RNA (ceRNA) that performs key functions in multiple biological processes. However, little is known about the roles of lncRNA under hypoxia stress in fish. Here, vascular endothelial growth factor-Aa (vegfaa) was cloned in rainbow trout (Oncorhynchus mykiss), with the complete cDNA sequence of 2914 bp, encoding 218 amino acids. The molecular weight of the protein was approximately 25.33 kDa, and contained PDGF and VEGF_C domains. Time-course and spatial expression patterns revealed that LOC110520012 was a key regulator of rainbow trout in response to hypoxia stress, and LOC110520012, miR-206-y and vegfaa exhibited a ceRNA regulatory relationship in liver, gill, muscle and rainbow trout liver cells treated with acute hypoxia. Subsequently, the targeting relationship of LOC110520012 and vegfaa with miR-206-y was confirmed by dual-luciferase reporter analysis, and overexpression of LOC110520012 mediated the inhibition of miR-206-y expression in rainbow trout liver cells, while the opposite results were obtained after LOC110520012 silencing with siRNA. We also proved that vegfaa was a target of miR-206-y in vitro and in vivo, and the vegfaa expression and anti-proliferative effect on rainbow trout liver cells regulated by miR-206-y mimics could be reversed by LOC110520012. These results suggested that LOC110520012 can positively regulate vegfaa expression by sponging miR-206-y under hypoxia stress in rainbow trout, which facilitate in-depth understanding of the molecular mechanisms of fish adaptation and tolerance to hypoxia.
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Affiliation(s)
- Shenji Wu
- College of Animal Science and Technology, Gansu Agricultural University, Lanzhou 730070, China
| | - Jinqiang Huang
- College of Animal Science and Technology, Gansu Agricultural University, Lanzhou 730070, China.
| | - Yongjuan Li
- College of Animal Science and Technology, Gansu Agricultural University, Lanzhou 730070, China; College of Science, Gansu Agricultural University, Lanzhou 730070, China
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2
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Gashkina NA. Metal Toxicity: Effects on Energy Metabolism in Fish. Int J Mol Sci 2024; 25:5015. [PMID: 38732234 PMCID: PMC11084289 DOI: 10.3390/ijms25095015] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2024] [Revised: 04/25/2024] [Accepted: 05/02/2024] [Indexed: 05/13/2024] Open
Abstract
Metals are dispersed in natural environments, particularly in the aquatic environment, and accumulate, causing adverse effects on aquatic life. Moreover, chronic polymetallic water pollution is a common problem, and the biological effects of exposure to complex mixtures of metals are the most difficult to interpret. In this review, metal toxicity is examined with a focus on its impact on energy metabolism. Mechanisms regulating adenosine triphosphate (ATP) production and reactive oxygen species (ROS) emission are considered in their dual roles in the development of cytotoxicity and cytoprotection, and mitochondria may become target organelles of metal toxicity when the transmembrane potential is reduced below its phosphorylation level. One of the main consequences of metal toxicity is additional energy costs, and the metabolic load can lead to the disruption of oxidative metabolism and enhanced anaerobiosis.
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Affiliation(s)
- Natalia A Gashkina
- Vernadsky Institute of Geochemistry and Analytical Chemistry, Russian Academy of Sciences, 19 Kosygin St., Moscow 119991, Russia
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Filice M, Gattuso A, Imbrogno S, Mazza R, Amelio D, Caferro A, Agnisola C, Icardo JM, Cerra MC. Functional, structural, and molecular remodelling of the goldfish (Carassius auratus) heart under moderate hypoxia. FISH PHYSIOLOGY AND BIOCHEMISTRY 2024; 50:667-685. [PMID: 38198074 PMCID: PMC11021278 DOI: 10.1007/s10695-024-01297-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/24/2023] [Accepted: 01/01/2024] [Indexed: 01/11/2024]
Abstract
The goldfish (Carassius auratus) is known for its physiologic ability to survive even long periods of oxygen limitation (hypoxia), adapting the cardiac performance to the requirements of peripheral tissue perfusion. We here investigated the effects of short-term moderate hypoxia on the heart, focusing on ventricular adaptation, in terms of hemodynamics and structural traits. Functional evaluations revealed that animals exposed to 4 days of environmental hypoxia increased the hemodynamic performance evaluated on ex vivo cardiac preparations. This was associated with a thicker and more vascularized ventricular compact layer and a reduced luminal lacunary space. Compared to normoxic animals, ventricular cardiomyocytes of goldfish exposed to hypoxia showed an extended mitochondrial compartment and a modulation of proteins involved in mitochondria dynamics. The enhanced expression of the pro-fission markers DRP1 and OMA1, and the modulation of the short and long forms of OPA1, suggested a hypoxia-related mitochondria fission. Our data propose that under hypoxia, the goldfish heart undergoes a structural remodelling associated with a potentiated cardiac activity. The energy demand for the highly performant myocardium is supported by an increased number of mitochondria, likely occurring through fission events.
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Affiliation(s)
- Mariacristina Filice
- Department of Biology, Ecology and Earth Sciences, University of Calabria, Arcavacata di Rende, Italy
| | - Alfonsina Gattuso
- Department of Biology, Ecology and Earth Sciences, University of Calabria, Arcavacata di Rende, Italy
| | - Sandra Imbrogno
- Department of Biology, Ecology and Earth Sciences, University of Calabria, Arcavacata di Rende, Italy.
| | - Rosa Mazza
- Department of Biology, Ecology and Earth Sciences, University of Calabria, Arcavacata di Rende, Italy
| | - Daniela Amelio
- Department of Biology, Ecology and Earth Sciences, University of Calabria, Arcavacata di Rende, Italy
| | - Alessia Caferro
- Department of Biology, Ecology and Earth Sciences, University of Calabria, Arcavacata di Rende, Italy
| | - Claudio Agnisola
- Department of Biological Sciences, University of Naples Federico II, Naples, Italy
| | - José Manuel Icardo
- Department of Anatomy and Cell Biology, University of Cantabria, Santander, Spain
| | - Maria Carmela Cerra
- Department of Biology, Ecology and Earth Sciences, University of Calabria, Arcavacata di Rende, Italy
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Ruiz N, García-Meilán I, Khansari AR, Teles M, Pastor J, Tort L. Repeated hypoxic episodes allow hematological and physiological habituation in rainbow trout. Front Physiol 2024; 15:1289903. [PMID: 38390451 PMCID: PMC10882073 DOI: 10.3389/fphys.2024.1289903] [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: 09/06/2023] [Accepted: 01/09/2024] [Indexed: 02/24/2024] Open
Abstract
Introduction: Under climate change, the increase in temperature in aquatic environments may induce oxygen depletion. In extreme cases, low oxygen may become a limiting factor for fish, thus generating stress. In addition, consecutive hypoxic episodes may complicate the recovery of individuals and hinder their ability to modulate physiological and biochemical responses to maintain homeostasis. Thus, the aim of this study was to determine the hematological and physiological responses of rainbow trout under a condition of repeated hypoxic and manipulation stresses at three different time points. Methods: Every hypoxic episode consisted of exposing the fish to low dissolved oxygen concentrations (2 mgO2/L for 1 h). Following the exposure, the fish were allowed to recover for 1 h, after which they were sampled to investigate hematological and physiological parameters. Results and discussion: The results showed a pattern of habituation reflected by values of hematocrit, hemoglobin, and mean corpuscular volume, indicating a certain ability of rainbow trout to resist this type of repeated hypoxic events, provided that the fish can have some recovery time between the exposures.
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Affiliation(s)
- Nuria Ruiz
- Department of Cell Biology, Physiology and Immunology, Universitat Autònoma de Barcelona, Barcelona, Spain
| | - Irene García-Meilán
- Department of Cell Biology, Physiology and Immunology, Universitat de Barcelona, Barcelona, Spain
| | - Ali Reza Khansari
- Department of Cell Biology, Physiology and Immunology, Universitat Autònoma de Barcelona, Barcelona, Spain
| | - Mariana Teles
- Department of Cell Biology, Physiology and Immunology, Universitat Autònoma de Barcelona, Barcelona, Spain
| | - Josep Pastor
- Departament of Animal Medicine and Surgery, Universitat Autònoma de Barcelona, Barcelona, Spain
| | - Lluís Tort
- Department of Cell Biology, Physiology and Immunology, Universitat Autònoma de Barcelona, Barcelona, Spain
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Ducros L, Touaibia M, Pichaud N, Lamarre SG. Resilience and phenotypic plasticity of Arctic char ( Salvelinus alpinus) facing cyclic hypoxia: insights into growth, energy stores and hepatic metabolism. CONSERVATION PHYSIOLOGY 2023; 11:coad099. [PMID: 38107465 PMCID: PMC10724465 DOI: 10.1093/conphys/coad099] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/18/2023] [Revised: 09/13/2023] [Accepted: 11/22/2023] [Indexed: 12/19/2023]
Abstract
Arctic char (Salvelinus alpinus) is facing the decline of its southernmost populations due to several factors including rising temperatures and eutrophication. These conditions are also conducive to episodes of cyclic hypoxia, another possible threat to this species. In fact, lack of oxygen and reoxygenation can both have serious consequences on fish as a result of altered ATP balance and an elevated risk of oxidative burst. Thus, fish must adjust their phenotype to survive and equilibrate their energetic budget. However, their energy allocation strategy could imply a reduction in growth which could be deleterious for their fitness. Although the impact of cyclic hypoxia is a major issue for ecosystems and fisheries worldwide, our knowledge on how salmonid deal with high oxygen fluctuations remains limited. Our objective was to characterize the effects of cyclic hypoxia on growth and metabolism in Arctic char. We monitored growth parameters (specific growth rate, condition factor), hepatosomatic and visceral indexes, relative heart mass and hematocrit of Arctic char exposed to 30 days of cyclic hypoxia. We also measured the hepatic protein synthesis rate, hepatic triglycerides as well as muscle glucose, glycogen and lactate and quantified hepatic metabolites during this treatment. The first days of cyclic hypoxia slightly reduce growth performance with a downward trend in specific growth rate in mass and condition factor variation compared to the control group. This acute exposure also induced a profound metabolome reorganization in the liver with an alteration of amino acid, carbohydrate and lipid metabolisms. However, fish rebalanced their metabolic activities and successfully maintained their growth and energetic reserves after 1 month of cyclic hypoxia. These results demonstrate the impressive ability of Arctic char to cope with its changing environment but also highlight a certain vulnerability of this species during the first days of a cyclic hypoxia event.
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Affiliation(s)
- Loïck Ducros
- Département de Biologie, Université de Moncton, 18 Antonine Maillet, Moncton E1A 3E9, NB, Canada
- Département de Chimie et Biochimie, Université de Moncton, 18 Antonine Maillet, Moncton E1A 3E9, NB, Canada
| | - Mohamed Touaibia
- Département de Chimie et Biochimie, Université de Moncton, 18 Antonine Maillet, Moncton E1A 3E9, NB, Canada
| | - Nicolas Pichaud
- Département de Chimie et Biochimie, Université de Moncton, 18 Antonine Maillet, Moncton E1A 3E9, NB, Canada
| | - Simon G Lamarre
- Département de Biologie, Université de Moncton, 18 Antonine Maillet, Moncton E1A 3E9, NB, Canada
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Duvall MS, Hagy JD, Ammerman JW, Tedesco MA. High-frequency dissolved oxygen dynamics in an urban estuary, the Long Island Sound. ESTUARIES AND COASTS : JOURNAL OF THE ESTUARINE RESEARCH FEDERATION 2023; 47:415-430. [PMID: 38993945 PMCID: PMC11235145 DOI: 10.1007/s12237-023-01278-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/10/2023] [Revised: 08/17/2023] [Accepted: 09/11/2023] [Indexed: 07/13/2024]
Abstract
The seasonal occurrence of deep-water hypoxia in western Long Island Sound (LIS) has been documented for decades by water quality cruise surveys and fixed mooring buoys. While previous studies have focused on factors modulating bottom dissolved oxygen (DO) at subtidal timescales, here we analyze continuous timeseries data from a moored buoy during summers 2021 and 2022 to examine factors controlling high-frequency fluctuations in surface and bottom DO at diurnal and semidiurnal timescales. Fluctuations in surface DO at diurnal timescales are associated with biological production, while fluctuations in bottom DO near semidiurnal timescales are associated with horizontal advection of DO by tides from the upper East River tidal strait into western LIS. Results from timeseries analysis are supported by weekly cruise surveys that resolve horizontal and vertical DO gradients in the western narrows. However, inferences regarding the duration of hypoxia during a given summer vary across datasets in part because weekly survey data do not resolve dominant timescales of variability within a particular summer. While prior studies have illustrated the importance of nutrient loading, stratification, and wind in controlling the development of hypoxia, the results presented here demonstrate the role of tidal advection in modulating hypoxia in far western LIS. Despite stronger stratification in 2021, the duration of hypoxia was 11.1 days shorter compared to 2022 in part due to greater advection of DO by tidal currents that intermittently increased bottom DO near the buoy. Furthermore, five-year averaged hypoxic area in the western narrows has increased since 2017, which highlights the spatially variable response of DO to nutrient load reductions. Future analysis of hypoxia in LIS should focus on leveraging high-frequency information contained in continuous datasets to improve estimates of hypoxia based on less temporally resolved water quality surveys.
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Affiliation(s)
- Melissa S Duvall
- U.S. Environmental Protection Agency, Long Island Sound Office, 888 Washington Blvd., Stamford, CT 06904 USA
| | - James D Hagy
- U.S. Environmental Protection Agency, Office of Research and Development, 27 Tarzwell Dr., Narragansett, RI 02882 USA
| | - James W Ammerman
- Long Island Sound Study/NEIWPCC, 888 Washington Blvd., Stamford, CT 06904 USA
- School of Marine and Atmospheric Sciences, Stony Brook University, Stony Brook, NY 11794
| | - Mark A Tedesco
- U.S. Environmental Protection Agency, Long Island Sound Office, 888 Washington Blvd., Stamford, CT 06904 USA
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Jiang T, Liang YS, Gu Y, Yao FC, Liu YF, Zhang KX, Song FB, Sun JL, Luo J. Different reoxygenation rates induce different metabolic, apoptotic and immune responses in Golden Pompano (Trachinotus blochii) after hypoxic stress. FISH & SHELLFISH IMMUNOLOGY 2023; 135:108640. [PMID: 36871632 DOI: 10.1016/j.fsi.2023.108640] [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: 11/29/2022] [Revised: 02/11/2023] [Accepted: 02/22/2023] [Indexed: 06/18/2023]
Abstract
Dissolved oxygen (DO) is essential for teleosts, and fluctuating environmental factors can result in hypoxic stress in the golden pompano (Trachinotus blochii). However, it is unknown whether different recovery speeds of DO concentration after hypoxia induce stress in T. blochii. In this study, T. blochii was subjected to hypoxic conditions (1.9 ± 0.2 mg/L) for 12 h followed by 12 h of reoxygenation at two different speeds (30 mg/L per hour and 1.7 mg/L per hour increasing). The gradual reoxygenation group (GRG), experienced DO recovery (1.9 ± 0.2 to 6.8 ± 0.2 mg/L) within 3 h, and the rapid reoxygenation group (RRG), experienced DO recovery (1.9 ± 0.2 to 6.8 ± 0.2 mg/L) within 10 min. Physiological and biochemical parameters of metabolism (glucose, glycegon, lactic acid (LD), lactate dehydrogenase (LDH), pyruvic acid (PA), phosphofructokinase (PFKA), and hexokinase (HK), triglyceride (TG), lipoprotein lipase (LPL), carnitine palmitoyltransferase 1 (CPT-1)) and transcriptome sequencing (RNA-seq of liver) were monitored to identify the effects of the two reoxygenation speeds. Increased LD content and increased activity of LDH, PA, PFKA, and HK suggested enhanced anaerobic glycolysis under hypoxic stress. LD and LDH levels remained significantly elevated during reoxygenation, indicating that the effects of hypoxia were not immediately alleviated during reoxygenation. The expressions of PGM2, PFKA, GAPDH, and PK were increased in the RRG, which suggests that glycolysis was enhanced. The same pattern was not observed in the GRG. Additionally, In the RRG, reoxygenation may promote glycolysis to guarantee energy supply. However, the GRG may through the lipid metabolism such as steroid biosynthesis at the later stage of reoxygenation. In the aspect of apoptosis, differentially expressed genes (DEGs) in the RRG were enriched in the p53 signaling pathway, which promoted cell apoptosis, while DEGs in the GRG seem to activate cell apoptosis at early stage of reoxygenation but was restrained latterly. DEGs in both the RRG and the GRG were enriched in the NF-kappa B and JAK-STAT signaling pathways, the RRG may induce cell survival by regulating the expression of IL-12B, COX2, and Bcl-XL, while in the GRG it may induce by regulating the expression of IL-8. Moreover, DEGs in the RRG were also enriched in the Toll-like receptor signaling pathway. This research revealed that at different velocity of reoxygenation after hypoxic stress, T. blochii would represent different metabolic, apoptotic and immune strategies, and this conclusion would provide new insight into the response to hypoxia and reoxygenation in teleosts.
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Affiliation(s)
- Tian Jiang
- State Key Laboratory of Marine Resource Utilization in South China Sea, Hainan Aquaculture Breeding Engineering Research Center, Hainan Academician Team Innovation Center, Hainan University, Haikou, 570228, China.
| | - Ye Song Liang
- State Key Laboratory of Marine Resource Utilization in South China Sea, Hainan Aquaculture Breeding Engineering Research Center, Hainan Academician Team Innovation Center, Hainan University, Haikou, 570228, China.
| | - Yue Gu
- State Key Laboratory of Marine Resource Utilization in South China Sea, Hainan Aquaculture Breeding Engineering Research Center, Hainan Academician Team Innovation Center, Hainan University, Haikou, 570228, China.
| | - Fu Cheng Yao
- State Key Laboratory of Marine Resource Utilization in South China Sea, Hainan Aquaculture Breeding Engineering Research Center, Hainan Academician Team Innovation Center, Hainan University, Haikou, 570228, China.
| | - Yi Fan Liu
- State Key Laboratory of Marine Resource Utilization in South China Sea, Hainan Aquaculture Breeding Engineering Research Center, Hainan Academician Team Innovation Center, Hainan University, Haikou, 570228, China.
| | - Kai Xi Zhang
- State Key Laboratory of Marine Resource Utilization in South China Sea, Hainan Aquaculture Breeding Engineering Research Center, Hainan Academician Team Innovation Center, Hainan University, Haikou, 570228, China.
| | - Fei Biao Song
- State Key Laboratory of Marine Resource Utilization in South China Sea, Hainan Aquaculture Breeding Engineering Research Center, Hainan Academician Team Innovation Center, Hainan University, Haikou, 570228, China.
| | - Jun Long Sun
- State Key Laboratory of Marine Resource Utilization in South China Sea, Hainan Aquaculture Breeding Engineering Research Center, Hainan Academician Team Innovation Center, Hainan University, Haikou, 570228, China.
| | - Jian Luo
- State Key Laboratory of Marine Resource Utilization in South China Sea, Hainan Aquaculture Breeding Engineering Research Center, Hainan Academician Team Innovation Center, Hainan University, Haikou, 570228, China.
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Wang S, Sun M, Ning Z, Chen Y, Zhou H, Mu W. The effects of sustained and diel-cycling hypoxia on high-latitude fish Phoxinus lagowskii. COMPARATIVE BIOCHEMISTRY AND PHYSIOLOGY. PART D, GENOMICS & PROTEOMICS 2023; 45:101059. [PMID: 36706598 DOI: 10.1016/j.cbd.2023.101059] [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: 12/27/2022] [Revised: 01/13/2023] [Accepted: 01/15/2023] [Indexed: 01/21/2023]
Abstract
High-latitude fish are subjected to sustained and diel-cycling hypoxia. Oxygen deficiency could pose a serious threat to fish, but little information is available regarding the response mechanisms employed by high-latitude fish to sustained and diel-cycling hypoxia. In this study, a combination of transcriptomics and metabolomics were used to examine the molecular response mechanisms actioned by sustained and diel-cycling hypoxia in the high-latitude fish, Phoxinus lagowskii. P. lagowskii was divided into normoxic control (6.0-7.0 mg/L dissolved oxygen), sustained (1.5 mg/L dissolved oxygen), and diel-cycling hypoxic treatment (6.0-7.0 mg/L between 07:00-21:00, and 3.0-4.0 mg/L between 21:00-07:00) tanks for 28 days. Differentially expressed genes (DEGs) and significantly different metabolites (DMs) related to digestive proteases, lipid metabolism, estrogen signaling pathway, steroid hormone biosynthesis, glutathione metabolism, and tryptophan metabolism were identified from comparative metabolomic and transcriptomic data expression profiles within the liver. The current study found that P. lagowskii had significantly different responses between sustained and diel-cycling hypoxia. P. lagowskii faced with sustained hypoxia may enhance their tolerance capacity through phospholipid and glutathione metabolism. Our data provide new insights into the high latitude fish coping with changes in hypoxia and warrants further investigation into these potentially important genes and metabolites.
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Affiliation(s)
- Sihan Wang
- Key Laboratory of Biodiversity of Aquatic Organisms, College of Life Science and Technology, Harbin Normal University, Harbin 150025, China
| | - Mingyang Sun
- Key Laboratory of Biodiversity of Aquatic Organisms, College of Life Science and Technology, Harbin Normal University, Harbin 150025, China
| | - Zhaoyang Ning
- Key Laboratory of Biodiversity of Aquatic Organisms, College of Life Science and Technology, Harbin Normal University, Harbin 150025, China
| | - Yingqiao Chen
- Key Laboratory of Biodiversity of Aquatic Organisms, College of Life Science and Technology, Harbin Normal University, Harbin 150025, China
| | - Haishui Zhou
- Key Laboratory of Biodiversity of Aquatic Organisms, College of Life Science and Technology, Harbin Normal University, Harbin 150025, China
| | - Weijie Mu
- Key Laboratory of Biodiversity of Aquatic Organisms, College of Life Science and Technology, Harbin Normal University, Harbin 150025, China.
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Gilthead Seabream Liver Integrative Proteomics and Metabolomics Analysis Reveals Regulation by Different Prosurvival Pathways in the Metabolic Adaptation to Stress. Int J Mol Sci 2022; 23:ijms232315395. [PMID: 36499720 PMCID: PMC9741202 DOI: 10.3390/ijms232315395] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2022] [Revised: 11/25/2022] [Accepted: 12/03/2022] [Indexed: 12/12/2022] Open
Abstract
The study of the molecular mechanisms of stress appraisal on farmed fish is paramount to ensuring a sustainable aquaculture. Stress exposure can either culminate in the organism's adaptation or aggravate into a metabolic shutdown, characterized by irreversible cellular damage and deleterious effects on fish performance, welfare, and survival. Multiomics can improve our understanding of the complex stressed phenotype in fish and the molecular mediators that regulate the underlying processes of the molecular stress response. We profiled the stress proteome and metabolome of Sparus aurata responding to different challenges common to aquaculture production, characterizing the disturbed pathways in the fish liver, i.e., the central organ in mounting the stress response. Label-free shotgun proteomics and untargeted metabolomics analyses identified 1738 proteins and 120 metabolites, separately. Mass spectrometry data have been made fully accessible via ProteomeXchange, with the identifier PXD036392, and via MetaboLights, with the identifier MTBLS5940. Integrative multivariate statistical analysis, performed with data integration analysis for biomarker discovery using latent components (DIABLO), depicted the 10 most-relevant features. Functional analysis of these selected features revealed an intricate network of regulatory components, modulating different signaling pathways related to cellular stress, e.g., the mTORC1 pathway, the unfolded protein response, endocytosis, and autophagy to different extents according to the stress nature. These results shed light on the dynamics and extent of this species' metabolic reprogramming under chronic stress, supporting future studies on stress markers' discovery and fish welfare research.
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Metabolomic Analysis of the Takifugu Obscurus Gill under Acute Hypoxic Stress. Animals (Basel) 2022; 12:ani12192611. [PMID: 36230352 PMCID: PMC9559691 DOI: 10.3390/ani12192611] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2022] [Revised: 09/19/2022] [Accepted: 09/26/2022] [Indexed: 11/16/2022] Open
Abstract
Simple Summary Takifugu obscurus is an economically important aquaculture species in China. In recent years, the development of the domestic breeding industry of the globefish has been very rapid. However, oxygen fluctuations and nourishing substances in the aquaculture water have caused oxygen deprivation, which makes great economic losses in high-density farming. As the main respiratory organ of fish, gills are greatly affected by changes in dissolved oxygen. Therefore, in this study, we explored the molecular mechanism of hypoxia tolerance of pufferfish by analyzing the changes of metabolites in gill tissue under acute hypoxia. These data provide a scientific basis for the control of dissolved oxygen in the aquatic environment of T. obscurus, and also provide a reference for the breeding of the new varieties with low oxygen tolerance. Abstract Takifugu obscurus has relatively small gills and gill pores. Consequently, a relatively low respiratory capacity. This fish is thus easily negatively affected by the low levels of dissolved oxygen (DO) that are common in high-intensity aquaculture. In order to clarify the mechanisms underlying the hypoxia response of T. obscurus, we used liquid mass spectrometry (LC–MS) to identify and quantify the metabolites present in the T. obscurus gill under the following conditions: normoxia (DO, 7.0 ± 0.2 mg/L), hypoxia (DO, 0.9 ± 0.2 mg/L), and reoxygenation (4, 12, and 24 h after return to normoxia conditions). We identified a total of 821 and 383 metabolites in the gill in positive and negative ion modes, respectively. Of the metabolites identified in positive ion mode, 136 were differentially abundant between hypoxia and all other conditions; of the metabolites identified in negative ion mode, 34 were differentially abundant between hypoxia and all other conditions. The metabolites which were differentially abundant under hypoxia primarily included glycerol phospholipids, fatty acids, hormones, and amino acids as well as related compounds. The pathways which were significantly enriched in the differentially abundant metabolites included the lipid metabolism, amino acid metabolism, purine metabolism, FoxO signaling pathway, and mTOR signaling pathway. Our results help to clarify the mechanisms underlying hypoxia tolerance and to identify hypoxia-related metabolites, as well as to highlight potential research targets for the development of hypoxic-tolerant strains in the future.
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Tandem Mass Tagging-Based Quantitative Proteomics Analysis Reveals Damage to the Liver and Brain of Hypophthalmichthys molitrix Exposed to Acute Hypoxia and Reoxygenation. Antioxidants (Basel) 2022; 11:antiox11030589. [PMID: 35326239 PMCID: PMC8945220 DOI: 10.3390/antiox11030589] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2022] [Revised: 03/15/2022] [Accepted: 03/18/2022] [Indexed: 12/13/2022] Open
Abstract
Aquaculture environments frequently experience hypoxia and subsequent reoxygenation conditions, which have significant effects on hypoxia-sensitive fish populations. In this study, hepatic biochemical activity indices in serum and the content of major neurotransmitters in the brain were altered markedly after acute hypoxia and reoxygenation exposure in silver carp (Hypophthalmichthys molitrix). Proteomics analysis of the liver showed that a number of immune-related and cytoskeletal organization-related proteins were downregulated, the ferroptosis pathway was activated, and several antioxidant molecules and detoxifying enzymes were upregulated. Proteomics analysis of the brain showed that somatostatin-1A (SST1A) was upregulated, dopamine-degrading enzyme catechol O methyltransferase (COMT) and ferritin, heavy subunit (FerH) were downregulated, and the levels of proteins involved in the nervous system were changed in different ways. In conclusion, these findings highlight that hypoxia–reoxygenation has potential adverse effects on growth, locomotion, immunity, and reproduction of silver carp, and represents a serious threat to liver and brain function, possibly via ferroptosis, oxidative stress, and cytoskeleton destruction in the liver, and abnormal expression of susceptibility genes for neurodegenerative disorders in the brain. Our present findings provide clues to the mechanisms of hypoxia and reoxygenation damage in the brain and liver of hypoxia-sensitive fish. They could also be used to develop methods to reduce hypoxia or reoxygenation injury to fish.
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Duvall MS, Jarvis BM, Hagy JD, Wan Y. Effects of Biophysical Processes on Diel-Cycling Hypoxia in a Subtropical Estuary. ESTUARIES AND COASTS : JOURNAL OF THE ESTUARINE RESEARCH FEDERATION 2022; 45:1615-1630. [PMID: 36505267 PMCID: PMC9727754 DOI: 10.1007/s12237-021-01040-y] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/06/2021] [Revised: 10/27/2021] [Accepted: 12/13/2021] [Indexed: 06/02/2023]
Abstract
In shallow estuaries, fluctuations in bottom dissolved oxygen (DO) at diel (24 h) timescales are commonly attributed to cycles of net production and respiration. However, bottom DO can also be modulated by physical processes, such as tides and wind, that vary at or near diel timescales. Here, we examine processes affecting spatiotemporal variations in diel-cycling DO in Escambia Bay, a shallow estuary along the Gulf of Mexico. We collected continuous water quality measurements in the upper and middle reaches of the Bay following relatively high (> 850 m3 s-1) and low (< 175 m3 s-1) springtime freshwater discharge. Variations in diel-cycling amplitude over time were estimated using the continuous wavelet transform, and correlations between DO and biophysical processes at diel timescales were examined using wavelet coherence. Our results reveal that freshwater discharge modulated inter-annual variations in the spatial extent and duration of summertime hypoxia through its effect on vertical density stratification. In the absence of strong stratification (> 15 kg m-3), vertical mixing by tropic tides and sea breeze enhanced diel fluctuations in deeper areas near the channel, while in shallower areas the largest fluctuations were associated with irradiance. Our findings suggest that processes affecting diel-cycling DO in the bottom layer can vary over a relatively short spatial extent less than 2 km and with relatively small changes in bottom elevation of 1 m or less. Implications for water quality monitoring were illustrated by subsampling DO timeseries, which demonstrates how low-frequency measurements may misrepresent water quality in estuaries where diel-cycling DO is common. In these systems, adequate assessment of hypoxia and its aquatic life impacts requires continuous measurements that capture the variation in DO at diel timescales.
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Affiliation(s)
- Melissa S Duvall
- Office of Research and Development, ORISE Research Participation Program, U.S. Environmental Protection Agency, 1 Sabine Island Dr, Gulf Breeze, FL, 32561, USA
| | - Brandon M Jarvis
- Office of Research and Development, U.S. Environmental Protection Agency, 1 Sabine Island Dr, Gulf Breeze, FL, 32561, USA
| | - James D Hagy
- Office of Research and Development, U.S. Environmental Protection Agency, 27 Tarzwell Dr, Narragansett, RI, 02882, USA
| | - Yongshan Wan
- Office of Research and Development, U.S. Environmental Protection Agency, 1 Sabine Island Dr, Gulf Breeze, FL, 32561, USA
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13
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Nancollas SJ, McGaw IJ. Acclimation to tidal conditions alters the physiological responses of the green shore crab, Carcinus maenas, to subsequent emersion. J Exp Biol 2021; 224:271088. [PMID: 34323277 DOI: 10.1242/jeb.242220] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2021] [Accepted: 06/28/2021] [Indexed: 11/20/2022]
Abstract
Animals inhabiting the intertidal zone are exposed to abrupt changes in environmental conditions associated with the rise and fall of the tide. For convenience, the majority of laboratory studies on intertidal organisms have acclimated individuals to permanently submerged conditions in seawater tanks. In this study, green shore crabs, Carcinus maenas, were acclimated to either a simulated tidal regime of continuous emersion-immersion ('tidal') or to permanently submerged conditions ('non-tidal') to assess their physiological responses to subsequent emersion. Tidal crabs exhibited an endogenous rhythm of oxygen consumption during continuous submersion with lower oxygen consumption during periods of anticipated emersion, which was not detected in non-tidal crabs. During emersion, tidal crabs were able to buffer apparent changes in acid-base balance and exhibited no change in venous pH, whereas non-tidal crabs developed an acidosis associated with a rise in lactate levels. These results indicate that tidal crabs were better able to sustain aerobic metabolism and had lower metabolic costs during emersion than non-tidal crabs. It is likely that the elevated levels of haemocyanin exhibited by tidal crabs allowed them to maintain oxygen transport and buffer pH changes during emersion. This suggests that acclimation of C. maenas to submerged conditions results in a loss of important physiological mechanisms that enable it to tolerate emersion. The results of this study show that caution must be taken when acclimating intertidal organisms to submerged conditions in the laboratory, as it may abolish important physiological responses and adaptations that are critical to their performance when exposed to air.
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Affiliation(s)
- Sarah J Nancollas
- Department of Ocean Sciences, 0 Marine Lab Road, Memorial University, St John's, NL, Canada, A1C 5S7
| | - Iain J McGaw
- Department of Ocean Sciences, 0 Marine Lab Road, Memorial University, St John's, NL, Canada, A1C 5S7
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14
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Morgenroth D, McArley T, Gräns A, Axelsson M, Sandblom E, Ekström A. Coronary blood flow influences tolerance to environmental extremes in fish. J Exp Biol 2021; 224:jeb.239970. [PMID: 33688058 DOI: 10.1242/jeb.239970] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2020] [Accepted: 03/03/2021] [Indexed: 12/16/2022]
Abstract
Approximately half of all fishes have, in addition to the luminal venous O2 supply, a coronary circulation supplying the heart with fully oxygenated blood. Yet, it is not fully understood how coronary O2 delivery affects tolerance to environmental extremes such as warming and hypoxia. Hypoxia reduces arterial oxygenation, while warming increases overall tissue O2 demand. Thus, as both stressors are associated with reduced venous O2 supply to the heart, we hypothesised that coronary flow benefits hypoxia and warming tolerance. To test this hypothesis, we blocked coronary blood flow (via surgical coronary ligation) in rainbow trout (Oncorhynchus mykiss) and assessed how in vivo cardiorespiratory performance and whole-animal tolerance to acute hypoxia and warming was affected. While coronary ligation reduced routine stroke volume relative to trout with intact coronaries, cardiac output was maintained by an increase in heart rate. However, in hypoxia, coronary-ligated trout were unable to increase stroke volume to maintain cardiac output when bradycardia developed, which was associated with a slightly reduced hypoxia tolerance. Moreover, during acute warming, coronary ligation caused cardiac function to collapse at lower temperatures and reduced overall heat tolerance relative to trout with intact coronary arteries. We also found a positive relationship between individual hypoxia and heat tolerance across treatment groups, and tolerance to both environmental stressors was positively correlated with cardiac performance. Collectively, our findings show that coronary perfusion improves cardiac O2 supply and therefore cardiovascular function at environmental extremes, which benefits tolerance to natural and anthropogenically induced environmental perturbations.
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Affiliation(s)
- Daniel Morgenroth
- Department of Biological and Environmental Sciences, University of Gothenburg, PO Box 463, 405 30 Gothenburg, Sweden
| | - Tristan McArley
- Department of Biological and Environmental Sciences, University of Gothenburg, PO Box 463, 405 30 Gothenburg, Sweden
| | - Albin Gräns
- Department of Animal Environment and Health, Swedish University of Agricultural Sciences, 532 23 Skara, Sweden
| | - Michael Axelsson
- Department of Biological and Environmental Sciences, University of Gothenburg, PO Box 463, 405 30 Gothenburg, Sweden
| | - Erik Sandblom
- Department of Biological and Environmental Sciences, University of Gothenburg, PO Box 463, 405 30 Gothenburg, Sweden
| | - Andreas Ekström
- Department of Biological and Environmental Sciences, University of Gothenburg, PO Box 463, 405 30 Gothenburg, Sweden
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15
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Driedzic WR, MacCormack TJ, Lamarre SG. Contrasting strategies of hypoxic cardiac performance and metabolism in cichlids and armoured catfish. JOURNAL OF EXPERIMENTAL ZOOLOGY PART 2021; 335:787-800. [PMID: 33830679 DOI: 10.1002/jez.2461] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/09/2021] [Revised: 03/19/2021] [Accepted: 03/22/2021] [Indexed: 11/07/2022]
Abstract
The heart of tropical fishes is a particularly useful model system in which to investigate mechanisms of hypoxic tolerance. Here we focus on insights gained from two groups of fishes, cichlids and armoured catfishes. Cichlids respond to hypoxia by entering a sustained hypometabolism with decreased heart performance to match whole animal circulatory needs. Heart rate is decreased along with protein turnover to reduce adenosine triphosphate demand. This occurs despite the inherent capacity for high levels of cardiac power development. Although highly hypoxic tolerant at the whole animal level, the heart of cichlids does not have high constitutive activities of glycolytic enzymes compared to other species. Information is conflicting with respect to changes in glycolytic gene expression and enzyme activity following hypoxic exposure with some studies showing increases and others decreases. In contrast to cichlids, species of armoured catfish, that are routinely exposed to water of low oxygen content, do not display hypoxic bradycardia. Under hypoxia there are early changes in glucose trafficking suggestive of activation of glycolysis before lactate accumulation. Thereafter, heart glycogen is mobilized and lactate accumulates in both heart and blood, in some species to very high levels. Heart performance under hypoxia is enhanced by defense of intracellular pH. A functional sarcoplasmic reticulum and binding of hexokinase to the outer mitochondrial membrane may also play a role in cardioprotection. Maintenance of heart performance under hypoxia may relate to a tradeoff between air breathing via a modified stomach and circulatory demands for digestion.
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Affiliation(s)
- William R Driedzic
- Department of Ocean Sciences, Memorial University of Newfoundland, St. John's, Newfoundland and Labrador, Canada
| | - Tyson J MacCormack
- Department of Chemistry and Biochemistry, Mount Allison University, Sackville, New Brunswick, Canada
| | - Simon G Lamarre
- Département de Biologie, Université de Moncton, Moncton, New Brunswick, Canada
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16
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Ouillon N, Sokolov EP, Otto S, Rehder G, Sokolova IM. Effects of variable oxygen regimes on mitochondrial bioenergetics and reactive oxygen species production in a marine bivalve, Mya arenaria. J Exp Biol 2021; 224:jeb.237156. [PMID: 33436367 DOI: 10.1242/jeb.237156] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2020] [Accepted: 01/06/2021] [Indexed: 12/12/2022]
Abstract
Estuarine and coastal benthic organisms often experience fluctuations in oxygen levels that can negatively impact their mitochondrial function and aerobic metabolism. To study these impacts, we exposed a common sediment-dwelling bivalve, the soft-shell clam Mya arenaria, for 21 days to chronic hypoxia (P O2 ∼4.1 kPa), cyclic hypoxia (P O2 ∼12.7-1.9 kPa, mean 5.7 kPa) or normoxia (P O2 ∼21.1 kPa). pH was manipulated to mimic the covariation in CO2/pH and oxygen levels in coastal hypoxic zones. Mitochondrial respiration, including proton leak, the capacity for oxidative phosphorylation (OXPHOS), the maximum activity of the electron transport system (ETS), reactive oxygen species (ROS) production, and activity and oxygen affinity of cytochrome c oxidase (CCO) were assessed. Acclimation to constant hypoxia did not affect the studied mitochondrial traits except for a modest decrease in the OXPHOS coupling efficiency. Cyclic hypoxia had no effect on OXPHOS or ETS capacity, but increased proton leak and lowered mitochondrial OXPHOS coupling efficiency. Furthermore, mitochondria of clams acclimated to cyclic hypoxia had higher rates of ROS generation compared with the clams acclimated to normoxia or chronic hypoxia. CCO activity was upregulated under cyclic hypoxia, but oxygen affinity of CCO did not change. These findings indicate that long-term cyclic hypoxia has a stronger impact on the mitochondria of M. arenaria than chronic hypoxia and might lead to impaired ATP synthesis, higher costs of mitochondrial maintenance and oxidative stress. These changes might negatively affect populations of M. arenaria in the coastal Baltic Sea under increasing hypoxia pressure.
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Affiliation(s)
- Natascha Ouillon
- Department of Marine Biology, Institute of Biological Sciences, University of Rostock, Rostock 18057, Germany
| | - Eugene P Sokolov
- Leibniz Institute for Baltic Research, Leibniz Science Campus Phosphorus Research Rostock, Rostock 18119, Germany
| | - Stefan Otto
- Department of Marine Chemistry, Leibniz Institute for Baltic Research, Rostock 18119, Germany
| | - Gregor Rehder
- Department of Marine Chemistry, Leibniz Institute for Baltic Research, Rostock 18119, Germany
| | - Inna M Sokolova
- Department of Marine Biology, Institute of Biological Sciences, University of Rostock, Rostock 18057, Germany .,Department of Maritime Systems, Interdisciplinary Faculty, University of Rostock, Rostock, Germany
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17
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Gerber L, Clow KA, Gamperl AK. Acclimation to warm temperatures has important implications for mitochondrial function in Atlantic salmon ( Salmo salar). J Exp Biol 2021; 224:jeb236257. [PMID: 33288533 DOI: 10.1242/jeb.236257] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2020] [Accepted: 12/01/2020] [Indexed: 12/16/2022]
Abstract
In fish, the capacity of thermal acclimation to preserve cardiac mitochondrial function under future warming scenarios is important to understand given the central roles that cardiac energy metabolism and performance play in this taxa's thermal tolerance. We acclimated Atlantic salmon to 12 and 20°C (for >2 months), and investigated the effects of acute and chronic warming on cardiac mitochondrial respiration and reactive oxygen species (ROS) production (release rate) using high-resolution fluorespirometry. Further, we compared the sensitivity of mitochondrial respiration to nitric oxide (i.e. the NO IC50), and assessed the mitochondrial response to anoxia-reoxygenation (AR). Acute exposure to 20°C increased maximal mitochondrial respiration by ∼55%; however, the mitochondria's complex I respiratory control ratio was 17% lower and ROS production was increased by ≥60%. Acclimation to 20°C: (1) preserved mitochondrial coupling and aerobic capacity; (2) decreased the mitochondria's ROS production by ∼30%; (3) increased the mitochondria's NO IC50 by ∼23%; and (4) improved mitochondrial membrane integrity at 20°C. AR did not affect mitochondrial function at 12°C, but acute exposure to 20°C and AR depressed maximal mitochondrial respiration (by ∼9%) and coupling (by ∼16%) without impacting ROS production. Finally, warm acclimation did not improve the capacity of mitochondria to recover from AR, indicating that there was no 'cross-tolerance' between these challenges. Our findings provide compelling evidence that thermal plasticity of cardiac mitochondrial function contributes to the Atlantic salmon's capability to survive at ≥20°C for prolonged periods, but call into question whether this plasticity may allow them to withstand high temperatures when combined with other stressors.
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Affiliation(s)
- Lucie Gerber
- Department of Ocean Sciences, Memorial University, St. John's, NL A1C 5S7, Canada
| | - Kathy A Clow
- Department of Ocean Sciences, Memorial University, St. John's, NL A1C 5S7, Canada
| | - Anthony K Gamperl
- Department of Ocean Sciences, Memorial University, St. John's, NL A1C 5S7, Canada
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18
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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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19
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Cassidy AA, Lamarre SG. Activation of oxygen-responsive pathways is associated with altered protein metabolism in Arctic char exposed to hypoxia. ACTA ACUST UNITED AC 2019; 222:jeb.203901. [PMID: 31704904 DOI: 10.1242/jeb.203901] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2019] [Accepted: 10/30/2019] [Indexed: 11/20/2022]
Abstract
Fish exposed to fluctuating oxygen concentrations often alter their metabolism and/or behaviour to survive. Hypoxia tolerance is typically associated with the ability to reduce energy demand by supressing metabolic processes such as protein synthesis. Arctic char is amongst the most sensitive salmonid to hypoxia, and typically engage in avoidance behaviour when faced with lack of oxygen. We hypothesized that a sensitive species will still have the ability (albeit reduced) to regulate molecular mechanisms during hypoxia. We investigated the tissue-specific response of protein metabolism during hypoxia. Little is known about protein degradation pathways during hypoxia in fish and we predict that protein degradation pathways are differentially regulated and play a role in the hypoxia response. We also studied the regulation of oxygen-responsive cellular signalling pathways [hypoxia inducible factor (HIF), unfolded protein response (UPR) and mTOR pathways] since most of what we know comes from studies on cancerous mammalian cell lines. Arctic char were exposed to cumulative graded hypoxia trials for 3 h at four air saturation levels (100%, 50%, 30% and 15%). The rate of protein synthesis was measured using a flooding dose technique, whereas protein degradation and signalling pathways were assessed by measuring transcripts and phosphorylation of target proteins. Protein synthesis decreased in all tissues measured (liver, muscle, gill, digestive system) except for the heart. Salmonid hearts have preferential access to oxygen through a well-developed coronary artery, therefore the heart is likely to be the last tissue to become hypoxic. Autophagy markers were upregulated in the liver, whereas protein degradation markers were downregulated in the heart during hypoxia. Further work is needed to determine the effects of a decrease in protein degradation on a hypoxic salmonid heart. Our study showed that protein metabolism in Arctic char is altered in a tissue-specific fashion during graded hypoxia, which is in accordance with the responses of the three major hypoxia-sensitive pathways (HIF, UPR and mTOR). The activation pattern of these pathways and the cellular processes that are under their control varies greatly among tissues, sometimes even going in the opposite direction. This study provides new insights on the effects of hypoxia on protein metabolism. Adjustment of these cellular processes is likely to contribute to shifting the fish phenotype into a more hypoxia-tolerant one, if more than one hypoxia event were to occur. Our results warrant studying these adjustments in fish exposed to long-term and diel cycling hypoxia.
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Affiliation(s)
- Alicia A Cassidy
- Département de Biologie, Université de Moncton, Moncton, NB, Canada, E1A 3E9
| | - Simon G Lamarre
- Département de Biologie, Université de Moncton, Moncton, NB, Canada, E1A 3E9
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