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Varma A, Storey KB. Hepatic citrate synthase suppression in the freeze-tolerant wood frog (Rana sylvatica). Int J Biol Macromol 2023; 242:124718. [PMID: 37148930 DOI: 10.1016/j.ijbiomac.2023.124718] [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: 02/06/2023] [Revised: 04/11/2023] [Accepted: 04/30/2023] [Indexed: 05/08/2023]
Abstract
The wood frog, Rana sylvatica endures whole body freezing for weeks/months while overwintering at subzero temperatures. Survival of long-term freezing requires not only cryoprotectants but also strong metabolic rate depression (MRD) and reorganization of essential processes in order to maintain a balance between ATP-producing and ATP-consuming processes. Citrate synthase (CS) (E.C. 2.3.3.1) is an important irreversible enzyme of the tricarboxylic acid (TCA) cycle and forms a crucial checkpoint for many metabolic processes. Present study investigated the regulation of CS from wood frog liver during freezing. CS was purified to homogeneity by a two-step chromatographic process. Kinetic and regulatory parameters of the enzyme were investigated and, notably, demonstrated a significant decrease in the Vmax of the purified form of CS from frozen frogs as compared to controls when assayed at both 22 °C and 5 °C. This was further supported by a decrease in the maximum activity of CS from liver of frozen frogs. Immunoblotting also showed changes in posttranslational modifications with a significant decrease in threonine phosphorylation (by 49 %) for CS from frozen frogs. Taken together, these results suggest that CS is suppressed and TCA flux is inhibited during freezing, likely to support MRD survival of harsh winters.
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Affiliation(s)
- Anchal Varma
- Institute of Biochemistry & Department of Biology, Carleton University, 1125 Colonel by Drive, Ottawa, Ontario K1S 5B6, Canada
| | - Kenneth B Storey
- Institute of Biochemistry & Department of Biology, Carleton University, 1125 Colonel by Drive, Ottawa, Ontario K1S 5B6, Canada.
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2
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Cerra MC, Filice M, Caferro A, Mazza R, Gattuso A, Imbrogno S. Cardiac Hypoxia Tolerance in Fish: From Functional Responses to Cell Signals. Int J Mol Sci 2023; 24:ijms24021460. [PMID: 36674975 PMCID: PMC9866870 DOI: 10.3390/ijms24021460] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2022] [Revised: 01/09/2023] [Accepted: 01/10/2023] [Indexed: 01/14/2023] Open
Abstract
Aquatic animals are increasingly challenged by O2 fluctuations as a result of global warming, as well as eutrophication processes. Teleost fish show important species-specific adaptability to O2 deprivation, moving from intolerance to a full tolerance of hypoxia and even anoxia. An example is provided by members of Cyprinidae which includes species that are amongst the most tolerant hypoxia/anoxia teleosts. Living at low water O2 requires the mandatory preservation of the cardiac function to support the metabolic and hemodynamic requirements of organ and tissues which sustain whole organism performance. A number of orchestrated events, from metabolism to behavior, converge to shape the heart response to the restricted availability of the gas, also limiting the potential damages for cells and tissues. In cyprinids, the heart is extraordinarily able to activate peculiar strategies of functional preservation. Accordingly, by using these teleosts as models of tolerance to low O2, we will synthesize and discuss literature data to describe the functional changes, and the major molecular events that allow the heart of these fish to sustain adaptability to O2 deprivation. By crossing the boundaries of basic research and environmental physiology, this information may be of interest also in a translational perspective, and in the context of conservative physiology, in which the output of the research is applicable to environmental management and decision making.
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3
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Smith KLM, Swiderska A, Lock MC, Graham L, Iswari W, Choudhary T, Thomas D, Kowash HM, Desforges M, Cottrell EC, Trafford AW, Giussani DA, Galli GLJ. Chronic developmental hypoxia alters mitochondrial oxidative capacity and reactive oxygen species production in the fetal rat heart in a sex-dependent manner. J Pineal Res 2022; 73:e12821. [PMID: 35941749 PMCID: PMC9540814 DOI: 10.1111/jpi.12821] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/26/2022] [Revised: 07/28/2022] [Accepted: 08/03/2022] [Indexed: 11/29/2022]
Abstract
Insufficient oxygen supply (hypoxia) during fetal development leads to cardiac remodeling and a predisposition to cardiovascular disease in later life. Previous work has shown hypoxia causes oxidative stress in the fetal heart and alters the activity and expression of mitochondrial proteins in a sex-dependent manner. However, the functional effects of these modifications on mitochondrial respiration remain unknown. Furthermore, while maternal antioxidant treatments are emerging as a promising new strategy to protect the hypoxic fetus, whether these treatments convey similar protection to cardiac mitochondria in the male or female fetus has not been investigated. Therefore, using an established rat model, we measured the sex-dependent effects of gestational hypoxia and maternal melatonin treatment on fetal cardiac mitochondrial respiration, reactive oxygen species (ROS) production, and lipid peroxidation. Pregnant Wistar rats were subjected to normoxia or hypoxia (13% oxygen) during gestational days (GDs) 6-20 (term ~22 days) with or without melatonin treatment (5 µg/ml in maternal drinking water). On GD 20, mitochondrial aerobic respiration and H2 O2 production were measured in fetal heart tissue, together with lipid peroxidation and citrate synthase (CS) activity. Gestational hypoxia reduced maternal body weight gain (p < .01) and increased placental weight (p < .05) but had no effect on fetal weight or litter size. Cardiac mitochondria from male but not female fetuses of hypoxic pregnancy had reduced respiratory capacity at Complex II (CII) (p < .05), and an increase in H2 O2 production/O2 consumption (p < .05) without any changes in lipid peroxidation. CS activity was also unchanged in both sexes. Despite maternal melatonin treatment increasing maternal and fetal plasma melatonin concentration (p < .001), melatonin treatment had no effect on any of the mitochondrial parameters investigated. To conclude, we show that gestational hypoxia leads to ROS generation from the mitochondrial electron transport chain and affects fetal cardiac mitochondrial respiration in a sex-dependent manner. We also show that maternal melatonin treatment had no effect on these relationships, which has implications for the development of future therapies for hypoxic pregnancies.
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Affiliation(s)
- Kerri L. M. Smith
- Division of Cardiovascular Sciences, School of Medical Sciences, Faculty of Biology, Medicine and HealthUniversity of ManchesterManchesterUK
| | - Agnieszka Swiderska
- Division of Cardiovascular Sciences, School of Medical Sciences, Faculty of Biology, Medicine and HealthUniversity of ManchesterManchesterUK
| | - Mitchell C. Lock
- Division of Cardiovascular Sciences, School of Medical Sciences, Faculty of Biology, Medicine and HealthUniversity of ManchesterManchesterUK
| | - Lucia Graham
- Division of Cardiovascular Sciences, School of Medical Sciences, Faculty of Biology, Medicine and HealthUniversity of ManchesterManchesterUK
| | - Wulan Iswari
- Division of Cardiovascular Sciences, School of Medical Sciences, Faculty of Biology, Medicine and HealthUniversity of ManchesterManchesterUK
| | - Tashi Choudhary
- Division of Cardiovascular Sciences, School of Medical Sciences, Faculty of Biology, Medicine and HealthUniversity of ManchesterManchesterUK
| | - Donna Thomas
- Division of Cardiovascular Sciences, School of Medical Sciences, Faculty of Biology, Medicine and HealthUniversity of ManchesterManchesterUK
| | - Hager M. Kowash
- Division of Cardiovascular Sciences, School of Medical Sciences, Faculty of Biology, Medicine and HealthUniversity of ManchesterManchesterUK
| | - Michelle Desforges
- Division of Cardiovascular Sciences, School of Medical Sciences, Faculty of Biology, Medicine and HealthUniversity of ManchesterManchesterUK
| | - Elizabeth C. Cottrell
- Division of Cardiovascular Sciences, School of Medical Sciences, Faculty of Biology, Medicine and HealthUniversity of ManchesterManchesterUK
| | - Andrew W. Trafford
- Division of Cardiovascular Sciences, School of Medical Sciences, Faculty of Biology, Medicine and HealthUniversity of ManchesterManchesterUK
| | - Dino A. Giussani
- Department of Physiology Development and NeuroscienceUniversity of CambridgeCambridgeUK
| | - Gina L. J. Galli
- Division of Cardiovascular Sciences, School of Medical Sciences, Faculty of Biology, Medicine and HealthUniversity of ManchesterManchesterUK
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4
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Gandhi S, Chinnadurai V, Bhadra K, Gupta I, Kanwar RS. Urinary metabolic modulation in human participants residing in Siachen: a 1H NMR metabolomics approach. Sci Rep 2022; 12:9070. [PMID: 35641596 PMCID: PMC9156790 DOI: 10.1038/s41598-022-13031-5] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2022] [Accepted: 05/19/2022] [Indexed: 12/15/2022] Open
Abstract
The main physiological challenge in high altitude environment is hypoxia which affects the aerobic metabolism reducing the energy supply. These changes may further progress toward extreme environment-related diseases. These are further reflected in changes in small molecular weight metabolites and metabolic pathways. In the present study, metabolic changes due to chronic environmental hypoxia were assessed using 1H NMR metabolomics by analysing the urinary metabolic profile of 70 people at sea level and 40 people at Siachen camp (3700 m) for 1 year. Multivariate statistical analysis was carried out, and PLSDA detected 15 metabolites based on VIP score > 1. ROC analysis detected cis-aconitate, Nicotinamide Mononucleotide, Tyrosine, Choline and Creatinine metabolites with a high range of sensitivity and specificity. Pathway analysis revealed 16 pathways impact > 0.05, and phenylalanine tyrosine and tryptophan biosynthesis was the most prominent altered pathway indicating metabolic remodelling to meet the energy requirements. TCA cycle, Glycine serine and Threonine metabolism, Glutathione metabolism and Cysteine alterations were other metabolic pathways affected during long-term high-altitude hypoxia exposure. Present findings will help unlock a new dimension for the potential application of NMR metabolomics to address extreme environment-related health problems, early detection and developing strategies to combat high altitude hypoxia.
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Affiliation(s)
- Sonia Gandhi
- Metabolomics Research Facility, Institute of Nuclear Medicine and Allied Sciences (INMAS), Lucknow Road, Timarpur, Delhi, 110054, India.
| | - Vijayakumar Chinnadurai
- Cognitive Control and Machine Learning Centre, Institute of Nuclear Medicine and Allied Sciences, Delhi, 110054, India
| | - Kuntal Bhadra
- Department of Endocrinology and Thyroid Research Centre, Institute of Nuclear Medicine and Allied Sciences, Delhi, 110054, India
| | - Isha Gupta
- Metabolomics Research Facility, Institute of Nuclear Medicine and Allied Sciences (INMAS), Lucknow Road, Timarpur, Delhi, 110054, India
| | - Ratnesh Singh Kanwar
- Department of Endocrinology and Thyroid Research Centre, Institute of Nuclear Medicine and Allied Sciences, Delhi, 110054, India
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5
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Niu Y, Zhang X, Zhang H, Xu T, Zhu L, Storey KB, Chen Q. Metabolic responses of plasma to extreme environments in overwintering Tibetan frogs Nanorana parkeri: a metabolome integrated analysis. Front Zool 2021; 18:41. [PMID: 34454525 PMCID: PMC8403389 DOI: 10.1186/s12983-021-00428-7] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2021] [Accepted: 08/20/2021] [Indexed: 12/13/2022] Open
Abstract
Many animals lower their metabolic rate in response to low temperatures and scarcity of food in the winter in phenomena called hibernation or overwintering. Living at high altitude on the Tibetan Plateau where winters are very cold, the frog Nanorana parkeri, survives in one of the most hostile environments on Earth but, to date, relatively little is known about the biochemical and physiological adjustments for overwintering by this species. The present study profiled changes in plasma metabolites of N. parkeri between winter and summer using UHPLC-QE-MS non-target metabolomics in order to explore metabolic adaptations that support winter survival. The analysis showed that, in total, 11 metabolites accumulated and 95 were reduced in overwintering frogs compared with summer-active animals. Metabolites that increased included some that may have antioxidant functions (canthaxanthin, galactinol), act as a metabolic inhibitor (mono-ethylhexylphthalate), or accumulate as a product of anaerobic metabolism (lactate). Most other metabolites in plasma showed reduced levels in winter and were generally involved in energy metabolism including 11 amino acids (proline, isoleucine, leucine, valine, phenylalanine, tyrosine, arginine, tryptophan, methionine, threonine and histidine) and 4 carbohydrates (glucose, citrate, succinate, and malate). Pathway analysis indicated that aminoacyl-tRNA biosynthesis, phenylalanine, tyrosine and tryptophan biosynthesis, and nitrogen metabolism were potentially the most prominently altered pathways in overwintering frogs. Changes to these pathways are likely due to fasting and global metabolic depression in overwintering frogs. Concentrations of glucose and urea, commonly used as cryoprotectants by amphibians that winter on land, were significantly reduced during underwater hibernation in N. parkeri. In conclusion, winter survival of the high-altitude frog, N. parkeri was accompanied by substantial changes in metabolomic profiles and this study provides valuable information towards understanding the special adaptive mechanisms of N. parkeri to winter stresses.
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Affiliation(s)
- Yonggang Niu
- School of Life Sciences, Dezhou University, Dezhou, 253023, Shandong, China. .,School of Life Sciences, Lanzhou University, Lanzhou, 730000, Gansu, China.
| | - Xuejing Zhang
- School of Life Sciences, Dezhou University, Dezhou, 253023, Shandong, China
| | - Haiying Zhang
- School of Life Sciences, Dezhou University, Dezhou, 253023, Shandong, China
| | - Tisen Xu
- School of Life Sciences, Dezhou University, Dezhou, 253023, Shandong, China
| | - Lifeng Zhu
- School of Life Sciences, Nanjing Normal University, Nanjing, China
| | - Kenneth B Storey
- Department of Biology, Carleton University, Ottawa, ON, K1S 5B6, Canada
| | - Qiang Chen
- School of Life Sciences, Lanzhou University, Lanzhou, 730000, Gansu, China.
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6
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Patnaik P, Sahoo DD. Variations in oxidative stress and antioxidant defense level during different phases of hibernation in common Asian toad, Duttaphrynus melanostictus. Biol Open 2021; 10:bio058567. [PMID: 34350459 PMCID: PMC8353263 DOI: 10.1242/bio.058567] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2021] [Accepted: 06/07/2021] [Indexed: 12/12/2022] Open
Abstract
To assess redox status during hibernation with metabolic depression, oxidative stress parameters and antioxidant defense were assessed during different phases of hibernation including active period, hibernation, arousal, and post-arousal period, in the liver and brain tissues of Duttaphrynus melanostictus. We hypothesized low levels of oxidative stress and antioxidant defense during the hibernation period in comparison to the summer active period, due to hypometabolism and their subsequent increase during the arousal period following an increase in body temperature and metabolism. Contrary to our hypothesis, increased oxidative stress with significantly higher lipid peroxidation, protein carbonylation, oxidized glutathione (GSSG): glutathione (GSH) ratio, and elevated antioxidants defense consisting of higher catalase activity and high ascorbic acid content to control oxidative stress were found during hibernation. However, GSH and uric acid levels were found low with super oxide dismutase (SOD) activities at a steady level during hibernation. Supporting our hypothesis, increased oxidative stress with high lipid peroxidation and GSSG:GSH ratio were found during arousal from hibernation owing to increased oxygen consumption and rewarming. Augmented catalase and SOD activities and nonenzymatic antioxidants (GSH, ascorbic acid, and uric acid) level were found to counteract oxidative stress during arousal periods as it was expected. A steady level of protein carbonylation, indicating no oxidative damage during arousal from hibernation due to elevated antioxidant defense, shows the significance of hibernation to overcome food and water scarcity and cold climatic condition. Decrease in antioxidants levels accompanying coming down of lipid peroxidation, protein carbonylation, and GSSG:GSH ratio to their lower levels during the post-arousal period showing normalcy in redox status as it was during active period indicates controllability of oxidative stress in hibernating toads.
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Affiliation(s)
- Prabhati Patnaik
- Assistant Scientific Officer, Regional Forensic Science Laboratory, Berhampur, Odisha 760007, India
| | - Deba Das Sahoo
- Post-Graduate Department of Zoology, S.C.S Autonomous College, Puri, Odisha 752001, India
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7
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Galli GLJ, Ruhr IM, Crossley J, Crossley DA. The Long-Term Effects of Developmental Hypoxia on Cardiac Mitochondrial Function in Snapping Turtles. Front Physiol 2021; 12:689684. [PMID: 34262478 PMCID: PMC8273549 DOI: 10.3389/fphys.2021.689684] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2021] [Accepted: 06/03/2021] [Indexed: 01/05/2023] Open
Abstract
It is well established that adult vertebrates acclimatizing to hypoxic environments undergo mitochondrial remodeling to enhance oxygen delivery, maintain ATP, and limit oxidative stress. However, many vertebrates also encounter oxygen deprivation during embryonic development. The effects of developmental hypoxia on mitochondrial function are likely to be more profound, because environmental stress during early life can permanently alter cellular physiology and morphology. To this end, we investigated the long-term effects of developmental hypoxia on mitochondrial function in a species that regularly encounters hypoxia during development-the common snapping turtle (Chelydra serpentina). Turtle eggs were incubated in 21% or 10% oxygen from 20% of embryonic development until hatching, and both cohorts were subsequently reared in 21% oxygen for 8 months. Ventricular mitochondria were isolated, and mitochondrial respiration and reactive oxygen species (ROS) production were measured with a microrespirometer. Compared to normoxic controls, juvenile turtles from hypoxic incubations had lower Leak respiration, higher P:O ratios, and reduced rates of ROS production. Interestingly, these same attributes occur in adult vertebrates that acclimatize to hypoxia. We speculate that these adjustments might improve mitochondrial hypoxia tolerance, which would be beneficial for turtles during breath-hold diving and overwintering in anoxic environments.
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Affiliation(s)
- Gina L. J. Galli
- Faculty of Biology, Medicine, and Health, School of Medical Sciences, The University of Manchester, Manchester, United Kingdom
| | - Ilan M. Ruhr
- Faculty of Biology, Medicine, and Health, School of Medical Sciences, The University of Manchester, Manchester, United Kingdom
| | - Janna Crossley
- Developmental Integrative Biology Research Group, Department of Biological Sciences, University of North Texas, Denton, TX, United States
| | - Dane A. Crossley
- Developmental Integrative Biology Research Group, Department of Biological Sciences, University of North Texas, Denton, TX, United States
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8
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Skeletal muscle of torpid Richardson's ground squirrels (Urocitellus richardsonii) exhibits a less active form of citrate synthase associated with lowered lysine succinylation. Cryobiology 2021; 101:28-37. [PMID: 34186087 DOI: 10.1016/j.cryobiol.2021.06.006] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2021] [Revised: 06/22/2021] [Accepted: 06/23/2021] [Indexed: 11/21/2022]
Abstract
Hibernation is a metabolic/physiological strategy employed by many mammals to cope with periods when energy usage is greater than its input. Animals undergoing hibernation need to greatly reduce their metabolic rate and reshape their catabolic processes to survive on stored triglycerides. Citrate synthase (CS) is one of only two irreversible steps in the citric acid cycle (CAC) and forms an important regulatory checkpoint that gates the entry of acetyl-CoA formed in glycolysis or fatty acid catabolism into this critical central metabolic hub. This study investigated the regulation of citrate synthase in the muscle tissue of a small mammalian hibernator through comparison of functional and structural properties. The results demonstrated a significant decrease in the Vmax of purified torpid CS compared to the control euthermic enzyme (1.2-1.7 fold greater in the control) that was evident over a wide range of temperatures (8, 22 and 37 °C) that are encountered by the enzyme in hibernation. This was also reflected in the specific activity of the enzyme in crude muscle protein extracts. Analyzing the purified CS through immunoblotting demonstrated that the enzyme contained noticeably less lysine succinylation in the torpid state (about 50% of euthermic levels) and this was correlated with an increase in total levels of SIRT5, the enzyme responsible for mediating desuccinylation in the mitochondria (2.2 fold increase). Taken together, the results of this study support the idea that CS is inhibited during hibernation in the ground squirrel skeletal muscle and that this alteration could be mediated by decreases in succinylation.
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9
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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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10
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Niu Y, Cao W, Storey KB, He J, Wang J, Zhang T, Tang X, Chen Q. Metabolic characteristics of overwintering by the high-altitude dwelling Xizang plateau frog, Nanorana parkeri. J Comp Physiol B 2020; 190:433-444. [PMID: 32274534 DOI: 10.1007/s00360-020-01275-4] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2019] [Revised: 03/20/2020] [Accepted: 03/27/2020] [Indexed: 12/12/2022]
Abstract
The Xizang plateau frog, Nanorana parkeri, has the highest altitudinal distribution of all frogs in the world and survives the cold of winter without feeding by entering into a hibernating state. However, little attention has been paid to its physiological and biochemical characteristics that support overwintering underwater in small ponds. Here, we measured metabolic rate and heart rate, and collected liver and muscle samples from N. parkeri in summer and winter for analysis of mitochondrial respiration rate, and activities and relative mRNA transcript expression of metabolic enzymes. Compared with summer-collected frogs, both resting metabolic rate and heart rate were significantly reduced in winter-collected frogs. Both state 3 and state 4 respiration of liver mitochondria were also significantly reduced in winter but muscle mitochondria showed a decline only in state 3 respiration in winter. The activities and corresponding mRNA expression of cytochrome c oxidase showed a marked decline in winter, whereas the activities and corresponding mRNA expression of lactate dehydrogenase increased in winter-collected frogs, compared to summer. The thermal sensitivity (Q10 values) for state 3 respiration rate by liver mitochondria, and activities of lactate dehydrogenase, and cytochrome c oxidase all increased in winter-collected frogs, compared with summer frogs, suggesting that overwintering frogs were more sensitive to changes in external temperature. Enzyme changes mainly result from lower overall quantities of these enzymes as well as post-translational modifications. We conclude that overwintering N. parkeri exhibit a seasonal, temperature-independent suppression of metabolism that is mediated at multiple levels: physiological, mitochondrial, gene expression and enzyme activity levels.
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Affiliation(s)
- Yonggang Niu
- School of Life Sciences, Dezhou University, Dezhou, China.,Institute of Biochemistry and Molecular Biology, School of Life Sciences, Lanzhou University, Lanzhou, 730000, Gansu, China.,State Key Laboratory of Plateau Ecology and Agriculture, Qinghai University, Xining, China
| | - Wangjie Cao
- Institute of Biochemistry and Molecular Biology, School of Life Sciences, Lanzhou University, Lanzhou, 730000, Gansu, China
| | - Kenneth B Storey
- Department of Biology, Carleton University, Ottawa, ON, K1S 5B6, Canada
| | - Jie He
- Institute of Biochemistry and Molecular Biology, School of Life Sciences, Lanzhou University, Lanzhou, 730000, Gansu, China
| | - Jinzhou Wang
- Institute of Biochemistry and Molecular Biology, School of Life Sciences, Lanzhou University, Lanzhou, 730000, Gansu, China
| | - Tao Zhang
- Institute of Biochemistry and Molecular Biology, School of Life Sciences, Lanzhou University, Lanzhou, 730000, Gansu, China
| | - Xiaolong Tang
- Institute of Biochemistry and Molecular Biology, School of Life Sciences, Lanzhou University, Lanzhou, 730000, Gansu, China
| | - Qiang Chen
- Institute of Biochemistry and Molecular Biology, School of Life Sciences, Lanzhou University, Lanzhou, 730000, Gansu, China. .,State Key Laboratory of Plateau Ecology and Agriculture, Qinghai University, Xining, China.
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11
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Gerber L, Clow KA, Katan T, Emam M, Leeuwis RHJ, Parrish CC, Gamperl AK. Cardiac mitochondrial function, nitric oxide sensitivity and lipid composition following hypoxia acclimation in sablefish. ACTA ACUST UNITED AC 2019; 222:jeb.208074. [PMID: 31645375 DOI: 10.1242/jeb.208074] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2019] [Accepted: 10/21/2019] [Indexed: 01/02/2023]
Abstract
In fishes, the effect of O2 limitation on cardiac mitochondrial function remains largely unexplored. The sablefish (Anoplopoma fimbria) encounters considerable variations in environmental oxygen availability, and is an interesting model for studying the effects of hypoxia on fish cardiorespiratory function. We investigated how in vivo hypoxia acclimation (6 months at 40% then 3 weeks at 20% air saturation) and in vitro anoxia-reoxygenation affected sablefish cardiac mitochondrial respiration and reactive oxygen species (ROS) release rates using high-resolution fluorespirometry. Further, we investigated how hypoxia acclimation affected the sensitivity of mitochondrial respiration to nitric oxide (NO), and compared mitochondrial lipid and fatty acid (FA) composition between groups. Hypoxia acclimation did not alter mitochondrial coupled or uncoupled respiration, or respiratory control ratio, ROS release rates, P 50 or superoxide dismutase activity. However, it increased citrate synthase activity (by ∼20%), increased the sensitivity of mitochondrial respiration to NO inhibition (i.e., the NO IC50 was 25% lower), and enhanced the recovery of respiration (by 21%) and reduced ROS release rates (by 25-30%) post-anoxia. In addition, hypoxia acclimation altered mitochondrial FA composition [increasing arachidonic acid (20:4ω6) and eicosapentaenoic acid (20:5ω3) proportions by 11 and 14%, respectively], and SIMPER analysis revealed that the phospholipid:sterol ratio was the largest contributor (24%) to the dissimilarity between treatments. Overall, these results suggest that hypoxia acclimation may protect sablefish cardiac bioenergetic function during or after periods of O2 limitation, and that this may be related to alterations in mitochondrial sensitivity to NO and to adaptive changes in membrane composition (fluidity).
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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
| | - Tomer Katan
- Department of Ocean Sciences, Memorial University, St. John's, NL A1C 5S7, Canada
| | - Mohamed Emam
- Department of Ocean Sciences, Memorial University, St. John's, NL A1C 5S7, Canada
| | - Robine H J Leeuwis
- 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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12
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Bundgaard A, Qvortrup K, Rasmussen LJ, Fago A. Turtles maintain mitochondrial integrity but reduce mitochondrial respiratory capacity in the heart after cold acclimation and anoxia. ACTA ACUST UNITED AC 2019; 222:jeb.200410. [PMID: 31097599 DOI: 10.1242/jeb.200410] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2019] [Accepted: 05/11/2019] [Indexed: 12/21/2022]
Abstract
Mitochondria are important to cellular homeostasis, but can become a dangerous liability when cells recover from hypoxia. Anoxia-tolerant freshwater turtles show reduced mitochondrial respiratory capacity and production of reactive oxygen species (ROS) after prolonged anoxia, but the mechanisms are unclear. Here, we investigated whether this mitochondrial suppression originates from downregulation of mitochondrial content or intrinsic activity by comparing heart mitochondria from (1) warm (25°C) normoxic, (2) cold-acclimated (4°C) normoxic and (3) cold-acclimated anoxic turtles. Transmission electron microscopy of heart ventricle revealed that these treatments did not affect mitochondrial volume density and morphology. Furthermore, neither enzyme activity, protein content nor supercomplex distribution of electron transport chain (ETC) enzymes changed significantly. Instead, our data imply that turtles inhibit mitochondrial respiration rate and ROS production by a cumulative effect of slight inhibition of ETC complexes. Together, these results show that maintaining mitochondrial integrity while inhibiting overall enzyme activities are important aspects of anoxia tolerance.
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Affiliation(s)
- Amanda Bundgaard
- Department of Bioscience, Aarhus University, 8000 Aarhus, Denmark
| | - Klaus Qvortrup
- Department of Biomedical Sciences/CFIM, University of Copenhagen, 2200 Copenhagen, Denmark
| | - Lene Juel Rasmussen
- Center for Healthy Aging, Department of Cellular and Molecular medicine, University of Copenhagen, 2200 Copenhagen, Denmark
| | - Angela Fago
- Department of Bioscience, Aarhus University, 8000 Aarhus, Denmark
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Gallo AC, Brasileiro CA, DE Barros FC, DE Carvalho JE. Thermal and salinity effects on locomotor performance of Thoropa taophora tadpoles (Anura, Cycloramphidae). Integr Zool 2019; 15:40-54. [PMID: 31149773 DOI: 10.1111/1749-4877.12405] [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] [Indexed: 11/28/2022]
Abstract
It is well known that environmental temperature influences several biological functions of ectotherms, notably in amphibians. The high permeability of anuran skin, associated with the effect of elevated environmental temperature, potentiates the dehydration process and this combination may restrict locomotor performance. Thoropa taophora is an endemic species from the Atlantic Rainforest whose tadpoles are semiterrestrial and predominantly diurnal, and are found in rocky seashores where they are exposed to sea spray and high temperatures. In this study we investigated how temperature and salinity conditions affect the locomotor performance in Thoropa taophora tadpoles. We also assessed how different osmotic concentrations affect the activity of the metabolic pathways that support muscle function. We measured the sprint speed of tadpoles of various sizes at different temperatures and salinities in the field. We also measured the activity of the enzymes pyruvate kinase (PK), lactate dehydrogenase (LDH) and citrate synthase (CS) in different temperatures and osmotic concentrations, and calculated the thermal sensitivity and the activity constants for each osmolality. Our results showed that, in general, sprint speed decreased with increasing temperature and salinity. However, whereas the effect of increased salinity was similar in smaller and larger tadpoles, increased temperature had a higher negative impact on sprint speed of larger tadpoles, thus indicating low thermal sensitivity of small tadpoles. PK and LDH thermal sensitivities and LDH constant of activity decreased as the osmolality increased. In conclusion, the locomotor capacity of tadpoles was decreased by temperature and salinity, which may be related to a decrease in anaerobic metabolism both in terms of sensitivity and total energy turnover through enzymatic activity. We discuss the ecological consequences, including the potential impacts on predator escape behavior promoted by changes in metabolism and locomotor performance in an early stage of development of this species.
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Affiliation(s)
- Antonio C Gallo
- Department of Ecology and Evolutionary Biology, Federal University of São Paulo, Diadema, São Paulo, Brazil
| | - Cinthia A Brasileiro
- Department of Ecology and Evolutionary Biology, Federal University of São Paulo, Diadema, São Paulo, Brazil
| | - Fábio Cury DE Barros
- Department of Ecology and Evolutionary Biology, Federal University of São Paulo, Diadema, São Paulo, Brazil
| | - José Eduardo DE Carvalho
- Department of Ecology and Evolutionary Biology, Federal University of São Paulo, Diadema, São Paulo, Brazil
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Cadiz L, Bundgaard A, Malte H, Fago A. Hypoxia enhances blood O 2 affinity and depresses skeletal muscle O 2 consumption in zebrafish (Danio rerio). Comp Biochem Physiol B Biochem Mol Biol 2019; 234:18-25. [PMID: 31075501 DOI: 10.1016/j.cbpb.2019.05.003] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2019] [Revised: 04/24/2019] [Accepted: 05/01/2019] [Indexed: 12/13/2022]
Abstract
Zebrafish (Danio rerio) are widely used animal models. Nevertheless, the mechanisms underlying hypoxia tolerance in this species have remained poorly understood. In the present study, we have determined the effects of hypoxia on blood-O2 transport properties and mitochondrial respiration rate in permeabilized muscle fibres of adult zebrafish exposed to either 1) a gradual decrease in O2 levels until fish lost equilibrium (~1 h, acute hypoxia), or 2) severe hypoxia (PO2 ∼ 15 Torr) for 48 h (prolonged hypoxia). Acute, short-term hypoxia caused an increase in hemoglobin (Hb) O2 affinity (decrease in P50), due to a decrease in erythrocyte ATP after erythrocyte swelling. No changes in isoHb expression patterns were observed between hypoxic and normoxic treatments. Prolonged hypoxia elicited additional reponses on O2 consumption: lactate accumulated in the blood, indicating that zebrafish relied on glycolysis for ATP production, and mitochondrial respiration of skeletal muscle was overall significantly inhibited. In addition, male zebrafish had higher hypoxia tolerance (measured as time to loss of equilibrium) than females. The present study contributes to our understanding of the adaptive mechanisms that allow zebrafish, and by inference other fish species, to cope with low O2 levels.
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Affiliation(s)
- Laura Cadiz
- Department of Bioscience, Aarhus University, DK-8000 Aarhus C, Denmark
| | - Amanda Bundgaard
- Department of Bioscience, Aarhus University, DK-8000 Aarhus C, Denmark
| | - Hans Malte
- Department of Bioscience, Aarhus University, DK-8000 Aarhus C, Denmark
| | - Angela Fago
- Department of Bioscience, Aarhus University, DK-8000 Aarhus C, Denmark.
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Chang H, Jiang S, Ma X, Peng X, Zhang J, Wang Z, Xu S, Wang H, Gao Y. Proteomic analysis reveals the distinct energy and protein metabolism characteristics involved in myofiber type conversion and resistance of atrophy in the extensor digitorum longus muscle of hibernating Daurian ground squirrels. COMPARATIVE BIOCHEMISTRY AND PHYSIOLOGY D-GENOMICS & PROTEOMICS 2018; 26:20-31. [PMID: 29482114 DOI: 10.1016/j.cbd.2018.02.002] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/06/2017] [Revised: 02/08/2018] [Accepted: 02/11/2018] [Indexed: 01/07/2023]
Abstract
Previous hibernation studies demonstrated that such a natural model of skeletal muscle disuse causes limited muscle atrophy and a significant fast-to-slow fiber type shift. However, the underlying mechanism as defined in a large-scale analysis remains unclarified. Isobaric tags for relative and absolute quantification (iTRAQ) based quantitative analysis were used to examine proteomic changes in the fast extensor digitorum longus muscles (EDL) of Daurian ground squirrels (Spermophilus dauricus). Although the wet weights and fiber cross-sectional area of the EDL muscle showed no significant decrease, the percentage of slow type fiber was 61% greater (P < 0.01) in the hibernation group. Proteomics analysis identified 264 proteins that were significantly changed (ratio < 0.83 or >1.2-fold and P < 0.05) in the hibernation group, of which 23 proteins were categorized into energy production and conversion and translation and 22 proteins were categorized into ribosomal structure and biogenesis. Along with the validation by western blot, MAPKAP kinase 2, ATP5D, ACADSB, calcineurin, CSTB and EIF2S were up-regulated in the hibernation group, whereas PDK4, COX II and EIF3C were down-regulated in the hibernation group. MAPKAP kinase 2 and PDK4 were associated with glycolysis, COX II and ATP5D were associated with oxidative phosphorylation, ACADSB was associated with fatty acid metabolism, calcineurin and CSTB were associated with catabolism, and EIF2S and EIF3C were associated with anabolism. Moreover, the total proteolysis rate of EDL in the hibernation group was significantly inhibited compared with that in the pre-hibernation group. These distinct energy and protein metabolism characteristics may be involved in myofiber type conversion and resistance to atrophy in the EDL of hibernating Daurian ground squirrels.
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Affiliation(s)
- Hui Chang
- Shaanxi Key Laboratory for Animal Conservation, Northwest University, Xi'an 710069, PR China; Key Laboratory of Resource Biology and Biotechnology in Western China, College of Life Sciences, Northwest University, Ministry of Education, Xi'an 710069, PR China
| | - Shanfeng Jiang
- Laboratory for Bone Metabolism, Key Laboratory for Space Bioscience and Biotechnology, School of Life Sciences, Northwestern Polytechnical University, Xi'an, Shaanxi 710072, PR China
| | - Xiufeng Ma
- Shaanxi Key Laboratory for Animal Conservation, Northwest University, Xi'an 710069, PR China
| | - Xin Peng
- Shaanxi Key Laboratory for Animal Conservation, Northwest University, Xi'an 710069, PR China
| | - Jie Zhang
- Shaanxi Key Laboratory for Animal Conservation, Northwest University, Xi'an 710069, PR China
| | - Zhe Wang
- Shaanxi Key Laboratory for Animal Conservation, Northwest University, Xi'an 710069, PR China
| | - Shenhui Xu
- Shaanxi Key Laboratory for Animal Conservation, Northwest University, Xi'an 710069, PR China
| | - Huiping Wang
- Shaanxi Key Laboratory for Animal Conservation, Northwest University, Xi'an 710069, PR China; Key Laboratory of Resource Biology and Biotechnology in Western China, College of Life Sciences, Northwest University, Ministry of Education, Xi'an 710069, PR China
| | - Yunfang Gao
- Shaanxi Key Laboratory for Animal Conservation, Northwest University, Xi'an 710069, PR China; Key Laboratory of Resource Biology and Biotechnology in Western China, College of Life Sciences, Northwest University, Ministry of Education, Xi'an 710069, PR China.
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Geisler CE, Kentch KP, Renquist BJ. Non-Mammalian Vertebrates: Distinct Models to Assess the Role of Ion Gradients in Energy Expenditure. Front Endocrinol (Lausanne) 2017; 8:224. [PMID: 28919880 PMCID: PMC5585156 DOI: 10.3389/fendo.2017.00224] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/30/2017] [Accepted: 08/18/2017] [Indexed: 12/21/2022] Open
Abstract
Animals store metabolic energy as electrochemical gradients. At least 50% of mammalian energy is expended to maintain electrochemical gradients across the inner mitochondrial membrane (H+), the sarcoplasmic reticulum (Ca++), and the plasma membrane (Na+/K+). The potential energy of these gradients can be used to perform work (e.g., transport molecules, stimulate contraction, and release hormones) or can be released as heat. Because ectothermic species adapt their body temperature to the environment, they are not constrained by energetic demands that are required to maintain a constant body temperature. In fact, ectothermic species expend seven to eight times less energy than similarly sized homeotherms. Accordingly, ectotherms adopt low metabolic rates to survive cold, hypoxia, and extreme bouts of fasting that would result in energy wasting, lactic acidosis and apoptosis, or starvation in homeotherms, respectively. Ectotherms have also evolved unique applications of ion gradients to allow for localized endothermy. Endothermic avian species, which lack brown adipose tissue, have been integral in assessing the role of H+ and Ca++ cycling in skeletal muscle thermogenesis. Accordingly, the diversity of non-mammalian vertebrate species allows them to serve as unique models to better understand the role of ion gradients in heat production, metabolic flux, and adaptation to stressors, including obesity, starvation, cold, and hypoxia.
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Affiliation(s)
- Caroline E. Geisler
- School of Animal and Comparative Biomedical Science, University of Arizona, Tucson, AZ, United States
| | - Kyle P. Kentch
- School of Animal and Comparative Biomedical Science, University of Arizona, Tucson, AZ, United States
| | - Benjamin J. Renquist
- School of Animal and Comparative Biomedical Science, University of Arizona, Tucson, AZ, United States
- *Correspondence: Benjamin J. Renquist,
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Jiang S, Guo S, Xue W, Wang H, Goswami N, Gao Y. Seasonal oxidative capacity of skeletal muscles in hibernating Daurian ground squirrels (Spermophilus dauricus). CAN J ZOOL 2015. [DOI: 10.1139/cjz-2015-0027] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
We investigated the mechanism of high oxidative capacity of skeletal muscles in hibernating Daurian ground squirrels (Spermophilus dauricus Brandt, 1843). Myoglobin (Mb) levels, as well as citrate synthase and lactate dehydrogenase (LDH) activities, were measured by spectrophotometry. Mb content in the soleus (SOL) muscle lasted from the beginning of hibernation to spring. Mb content in SOL was 87% higher in the hibernating group than in the summer group. Mb content in the extensor digitorum longus (EDL) muscle stayed at similar levels during the different periods of the year. Citrate synthase activity in SOL was 30% higher in the hibernating group than in the summer group. Meanwhile, citrate synthase activity in EDL did not change during hibernation. LDH activity in SOL was not different between the hibernating group and the summer active group, whereas LDH activity in EDL increased significantly (up to 11%) in the 2 days arousal after hibernation group compared with the hibernating group. We conclude that high oxidative capacity is provided by increased oxygen storage capacity of slow-twitch muscle fibers rather than from fast-twitch muscle fibers in hibernating animals.
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Affiliation(s)
- Shanfeng Jiang
- Key Laboratory of Resource Biology and Biotechnology in Western China (Northwest University), Ministry of Education, Xi’an, 71069, Peoople’s Republic of China
| | - Shupan Guo
- Key Laboratory of Resource Biology and Biotechnology in Western China (Northwest University), Ministry of Education, Xi’an, 71069, Peoople’s Republic of China
| | - Wei Xue
- Key Laboratory of Resource Biology and Biotechnology in Western China (Northwest University), Ministry of Education, Xi’an, 71069, Peoople’s Republic of China
| | - Huiping Wang
- Key Laboratory of Resource Biology and Biotechnology in Western China (Northwest University), Ministry of Education, Xi’an, 71069, Peoople’s Republic of China
| | - Nandu Goswami
- Institute of Physiology, Center of Physiological Medicine, Medical University Graz, Austria
| | - Yunfang Gao
- Key Laboratory of Resource Biology and Biotechnology in Western China (Northwest University), Ministry of Education, Xi’an, 71069, Peoople’s Republic of China
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Galli GLJ, Lau GY, Richards JG. Beating oxygen: chronic anoxia exposure reduces mitochondrial F1FO-ATPase activity in turtle (Trachemys scripta) heart. ACTA ACUST UNITED AC 2014; 216:3283-93. [PMID: 23926310 DOI: 10.1242/jeb.087155] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
The freshwater turtle Trachemys scripta can survive in the complete absence of O2 (anoxia) for periods lasting several months. In mammals, anoxia leads to mitochondrial dysfunction, which culminates in cellular necrosis and apoptosis. Despite the obvious clinical benefits of understanding anoxia tolerance, little is known about the effects of chronic oxygen deprivation on the function of turtle mitochondria. In this study, we compared mitochondrial function in hearts of T. scripta exposed to either normoxia or 2 weeks of complete anoxia at 5°C and during simulated acute anoxia/reoxygenation. Mitochondrial respiration, electron transport chain activities, enzyme activities, proton conductance and membrane potential were measured in permeabilised cardiac fibres and isolated mitochondria. Two weeks of anoxia exposure at 5°C resulted in an increase in lactate, and decreases in ATP, glycogen, pH and phosphocreatine in the heart. Mitochondrial proton conductance and membrane potential were similar between experimental groups, while aerobic capacity was dramatically reduced. The reduced aerobic capacity was the result of a severe downregulation of the F1FO-ATPase (Complex V), which we assessed as a decrease in enzyme activity. Furthermore, in stark contrast to mammalian paradigms, isolated turtle heart mitochondria endured 20 min of anoxia followed by reoxygenation without any impact on subsequent ADP-stimulated O2 consumption (State III respiration) or State IV respiration. Results from this study demonstrate that turtle mitochondria remodel in response to chronic anoxia exposure and a reduction in Complex V activity is a fundamental component of mitochondrial and cellular anoxia survival.
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Affiliation(s)
- Gina L J Galli
- Department of Zoology, The University of British Columbia, Vancouver, BC, Canada.
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Galli GLJ, Richards JG. Mitochondria from anoxia-tolerant animals reveal common strategies to survive without oxygen. J Comp Physiol B 2014; 184:285-302. [DOI: 10.1007/s00360-014-0806-3] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2013] [Revised: 01/09/2014] [Accepted: 01/17/2014] [Indexed: 12/15/2022]
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Zolfaghari PS, Pinto BB, Dyson A, Singer M. The metabolic phenotype of rodent sepsis: cause for concern? Intensive Care Med Exp 2013; 1:25. [PMID: 26266794 PMCID: PMC4797805 DOI: 10.1186/2197-425x-1-6] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2013] [Accepted: 10/10/2013] [Indexed: 01/19/2023] Open
Abstract
PURPOSE Rodent models of sepsis are frequently used to investigate pathophysiological mechanisms and to evaluate putative therapeutic strategies. However, preclinical efficacy in these models has failed to translate to the clinical setting. We thus questioned the representativeness of such models and herein report a detailed comparison of the metabolic and cardiovascular phenotypes of long-term faecal peritonitis in fluid-resuscitated rats and mice with similar mortality profiles. METHODS We conducted prospective laboratory-controlled studies in adult male Wistar rats and C57 black mice. Animals were made septic by intraperitoneal injection of faecal slurry. Rats received continuous intravenous fluid resuscitation, whereas mice received intermittent fluid boluses subcutaneously. Sham-treated animals served as controls. Survival was assessed over 72 h. In separate studies, whole body metabolism (O2 consumption, CO2 production) was measured over 24 h with echocardiography performed at early (6 h) and established (24 h) phases of sepsis. Blood gas analysis was performed at 6 h (rats) and 24 h (rats, mice). RESULTS Similar survival curves were seen in both rodent models with approximately 75% mortality at 72 h. In mice, sepsis caused severity-dependent falls in core temperature and global metabolism. Oxygen consumption in severely septic mice fell by 38% within 2 h, and 80% at 22 h compared with baseline values. This was only partially restored by external warming. By contrast, septic rats maintained core temperature; only severely affected animals showed a pre-mortem decline in oxygen consumption. Significant myocardial dysfunction was seen in mice during early and established sepsis, whereas peak velocity and other hemodynamic variables in rats were similar at 6 h and significantly worse by 24 h in severely septic animals only. CONCLUSIONS Markedly differing metabolic and cardiovascular profiles were seen in long-term fluid-resuscitated rat and mouse models of bacterial sepsis despite similar mortality. The mouse model, in particular, does not represent the human condition. We urge caution in applying findings in murine models to septic patients, both with regard to our understanding of pathophysiology and the failure to translate preclinical efficacy into successful clinical trials.
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Affiliation(s)
- Parjam S Zolfaghari
- Bloomsbury Institute of Intensive Care Medicine, University College London, Cruciform Building, Gower St, London, WC1E 6BT, UK,
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Tang X, Xin Y, Wang H, Li W, Zhang Y, Liang S, He J, Wang N, Ma M, Chen Q. Metabolic characteristics and response to high altitude in Phrynocephalus erythrurus (Lacertilia: Agamidae), a lizard dwell at altitudes higher than any other living lizards in the world. PLoS One 2013; 8:e71976. [PMID: 23951275 PMCID: PMC3737200 DOI: 10.1371/journal.pone.0071976] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2013] [Accepted: 07/07/2013] [Indexed: 11/18/2022] Open
Abstract
Metabolic response to high altitude remains poorly explored in reptiles. In the present study, the metabolic characteristics of Phrynocephaluserythrurus (Lacertilia: Agamidae), which inhabits high altitudes (4500 m) and Phrynocephalusprzewalskii (Lacertilia: Agamidae), which inhabits low altitudes, were analysed to explore the metabolic regulatory strategies for lizards living at high-altitude environments. The results indicated that the mitochondrial respiratory rates of P. erythrurus were significantly lower than those of P. przewalskii, and that proton leak accounts for 74~79% of state 4 and 7~8% of state3 in P. erythrurus vs. 43~48% of state 4 and 24~26% of state3 in P. przewalskii. Lactate dehydrogenase (LDH) activity in P. erythrurus was lower than in P. przewalskii, indicating that at high altitude the former does not, relatively, have a greater reliance on anaerobic metabolism. A higher activity related to β-hydroxyacyl coenzyme A dehydrogenase (HOAD) and the HOAD/citrate synthase (CS) ratio suggested there was a possible higher utilization of fat in P. erythrurus. The lower expression of PGC-1α and PPAR-γ in P. erythrurus suggested their expression was not influenced by cold and low PO2 at high altitude. These distinct characteristics of P. erythrurus are considered to be necessary strategies in metabolic regulation for living at high altitude and may effectively compensate for the negative influence of cold and low PO2.
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Affiliation(s)
- Xiaolong Tang
- Institute of Biochemistry and Molecular Biology, School of Life Science, Lanzhou University, Lanzhou, China
| | - Ying Xin
- Institute of Biochemistry and Molecular Biology, School of Life Science, Lanzhou University, Lanzhou, China
| | - Huihui Wang
- Institute of Biochemistry and Molecular Biology, School of Life Science, Lanzhou University, Lanzhou, China
| | - Weixin Li
- Institute of Biochemistry and Molecular Biology, School of Life Science, Lanzhou University, Lanzhou, China
| | - Yang Zhang
- Institute of Biochemistry and Molecular Biology, School of Life Science, Lanzhou University, Lanzhou, China
| | - Shiwei Liang
- Institute of Biochemistry and Molecular Biology, School of Life Science, Lanzhou University, Lanzhou, China
| | - Jianzheng He
- Institute of Biochemistry and Molecular Biology, School of Life Science, Lanzhou University, Lanzhou, China
| | - Ningbo Wang
- Institute of Biochemistry and Molecular Biology, School of Life Science, Lanzhou University, Lanzhou, China
| | - Ming Ma
- Institute of Biochemistry and Molecular Biology, School of Life Science, Lanzhou University, Lanzhou, China
| | - Qiang Chen
- Institute of Biochemistry and Molecular Biology, School of Life Science, Lanzhou University, Lanzhou, China
- * E-mail:
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da Silveira LC, do Nascimento LFR, Colquhoun A, Abe AS, de Souza SCR. Cardiac hypertrophy and structural and metabolic remodeling related to seasonal dormancy in the first annual cycle in tegu lizards. Comp Biochem Physiol A Mol Integr Physiol 2013; 165:371-80. [PMID: 23603066 DOI: 10.1016/j.cbpa.2013.04.006] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2013] [Revised: 04/09/2013] [Accepted: 04/11/2013] [Indexed: 11/16/2022]
Abstract
Morpho-functional adjustments in the heart of juvenile tegu lizards (Tupinambis merianae) were analyzed at distinct seasonal periods to investigate how the demands of growth and of energy saving are reconciled during the first annual cycle. The relative ventricular mass (Mv) was 31% and 69% larger in late autumn and winter dormancy, respectively, compared to early autumn. This effect did not persist during unfed arousal, suggesting that protein accumulates in the heart during hypometabolism and is degraded on arousal. Both the hypertrophy and the atrophy were disproportionate in the largest individuals. In contrast, Mv was smaller in lizards that were starved during spring activity compared to fed lizards, this effect being larger in smaller individuals. In late autumn and winter dormancy the spongy myocardium had 8% of the section area covered by lacunary spaces, which expanded after food intake during arousal and reached 29% in spring activity together with higher density of cardiomyocytes. Total and soluble proteins per mass unity were unchanged, and maximum activities of selected enzymes suggest sustained glycolytic and aerobic capacities during hypometabolism. Results indicate that important structural adjustments occur in the heart in anticipation of dormancy, and that the protein balance in the tissue is maintained at winter temperatures ~17°C.
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LIGON DAYB, PETERSON CHARLESC, LOVERN MATTHEWB. Acute and Persistent Effects of Pre- and Posthatching Thermal Environments on Growth and Metabolism in the Red-Eared Slider Turtle, Trachemys scripta elegans. ACTA ACUST UNITED AC 2012; 317:227-35. [DOI: 10.1002/jez.1716] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2011] [Revised: 10/14/2011] [Accepted: 11/24/2011] [Indexed: 11/07/2022]
Affiliation(s)
- DAY B. LIGON
- Department of Biology; Missouri State University; Springfield; Missouri
| | | | - MATTHEW B. LOVERN
- Department of Zoology; Oklahoma State University; Stillwater; Oklahoma
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Enzyme activity in the aestivating Green-striped burrowing frog (Cyclorana alboguttata). J Comp Physiol B 2010; 180:1033-43. [DOI: 10.1007/s00360-010-0471-0] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2009] [Revised: 03/11/2010] [Accepted: 03/13/2010] [Indexed: 10/19/2022]
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Berner NJ, Puckett RE. Phenotypic flexibility and thermoregulatory behavior in the eastern red-spotted newt (Notophthalmus viridescens viridescens). ACTA ACUST UNITED AC 2010; 313:231-9. [DOI: 10.1002/jez.596] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Petersen AM, Gleeson TT. Skeletal muscle substrate utilization is altered by acute and acclimatory temperature in the American bullfrog (Lithobates catesbeiana). ACTA ACUST UNITED AC 2009; 212:2378-85. [PMID: 19617430 DOI: 10.1242/jeb.023408] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
We investigated the effect of acute and acclimatory temperature on the relative contribution of g9lucose and lactate to metabolism in resting sartorius muscle of the American bullfrog (Lithobates catesbeiana). We examined the fate of these metabolites in vitro by supplying radiolabeled [(14)C]glucose, [(14)C]lactate and [(14)C]palmitate to isolated muscle bundles from frogs (1) acutely exposed to incubation conditions of 5, 15 or 25 degrees C, (2) acclimated for 2-6 weeks to 5 or 25 degrees C or (3) acclimated for 2-6 weeks to 5 or 25 degrees C and the muscles incubated at 15 degrees C. Under all three temperature conditions tested, net rate of lactate metabolism exceeded that of glucose. Acute exposure to 5 degrees C reduced net rate of glucose metabolism by 15x and net lactate metabolism by 10x as compared with 25 degrees C-exposed tissues. Acclimation to 5 degrees C favored glucose storage as glycogen and increased the proportion of lactate oxidized (versus stored or converted to glucose) when compared with 25 degrees C-acclimated tissues. Net rates of storage of lactate as glycogen (glyconeogenesis) were significantly higher in muscles from 5 degrees C-acclimated frogs during incubation at a common temperature of 15 degrees C. These data suggest that lactate is the predominant fuel for resting skeletal muscle over this temperature range, and particularly so under cold conditions. Ready use of lactate as a substrate, and enhancement of glyconeogenic pathways in response to cold acclimation, could play a role in the tolerance of this species to seasonal temperature changes by promoting sequestration and storage of available substrate under cold conditions.
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Affiliation(s)
- A M Petersen
- Wellesley College, 106 Central Street, Wellesley, MA 01778, USA.
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Chess DJ, Khairallah RJ, O'Shea KM, Xu W, Stanley WC. A high-fat diet increases adiposity but maintains mitochondrial oxidative enzymes without affecting development of heart failure with pressure overload. Am J Physiol Heart Circ Physiol 2009; 297:H1585-93. [PMID: 19767529 DOI: 10.1152/ajpheart.00599.2009] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
A high-fat diet can increase adiposity, leptin secretion, and plasma fatty acid concentration. In hypertension, this scenario may accelerate cardiac hypertrophy and development of heart failure but could be protective by activating peroxisome proliferator-activated receptors and expression of mitochondrial oxidative enzymes. We assessed the effects of a high-fat diet on the development of left ventricular hypertrophy, remodeling, contractile dysfunction, and the activity of mitochondrial oxidative enzymes. Mice (n = 10-12/group) underwent transverse aortic constriction (TAC) or sham surgery and were fed either a low-fat diet (10% of energy intake as fat) or a high-fat diet (45% fat) for 6 wk. The high-fat diet increased adipose tissue mass and plasma leptin and insulin. Left ventricular mass and chamber size were unaffected by diet in sham animals. TAC increased left ventricular mass (approximately 70%) and end-systolic and end-diastolic areas (approximately 100% and approximately 45%, respectively) to the same extent in both dietary groups. The high-fat diet increased plasma free fatty acid concentration and prevented the decline in the activity of the mitochondrial enzymes medium chain acyl-coenzyme A dehydrogenase (MCAD) and citrate synthase that was observed with TAC animals on a low-fat diet. In conclusion, a high-fat diet did not worsen cardiac hypertrophy or left ventricular chamber enlargement despite increases in fat mass and insulin and leptin concentrations. Furthermore, a high-fat diet preserved MCAD and citrate synthase activities during pressure overload, suggesting that it may help maintain mitochondrial oxidative capacity in failing myocardium.
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Affiliation(s)
- David J Chess
- Division of Cardiology, Department of Medicine, University of Maryland, Baltimore, Maryland, USA
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Berner NJ, Else PL, Hulbert AJ, Mantle BL, Cramp RL, Franklin CE. Metabolic depression during aestivation does not involve remodelling of membrane fatty acids in two Australian frogs. J Comp Physiol B 2009; 179:857-66. [DOI: 10.1007/s00360-009-0368-y] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2009] [Revised: 04/28/2009] [Accepted: 05/01/2009] [Indexed: 11/28/2022]
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Savina MV, Emelyanova LV, Brailovskaya IV. Bioenergetics of the lower vertebrates. Molecular mechanisms of adaptations to anoxia and hypoxia. J EVOL BIOCHEM PHYS+ 2009. [DOI: 10.1134/s0022093009020029] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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31
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Michaelidis B, Kyriakopoulou-Sklavounou P, Staikou A, Papathanasiou I, Konstantinou K. Glycolytic adjustments in tissues of frog Rana ridibunda and land snail Helix lucorum during seasonal hibernation. Comp Biochem Physiol A Mol Integr Physiol 2008; 151:582-9. [DOI: 10.1016/j.cbpa.2008.07.017] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2008] [Revised: 07/13/2008] [Accepted: 07/14/2008] [Indexed: 11/26/2022]
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Frick NT, Bystriansky JS, Ip YK, Chew SF, Ballantyne JS. Lipid, ketone body and oxidative metabolism in the African lungfish, Protopterus dolloi following 60 days of fasting and aestivation. Comp Biochem Physiol A Mol Integr Physiol 2008; 151:93-101. [DOI: 10.1016/j.cbpa.2008.06.004] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2008] [Revised: 06/03/2008] [Accepted: 06/04/2008] [Indexed: 10/21/2022]
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33
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Selman C, Evans PR. Alterations in tissue aerobic capacity may play a role in premigratory fattening in shorebirds. Biol Lett 2007; 1:101-4. [PMID: 17148139 PMCID: PMC1629051 DOI: 10.1098/rsbl.2004.0248] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Migratory shorebirds show regulated seasonal increases in body mass (BM) even in captivity, consisting primarily, but not exclusively, of fat. We examined whether captive red knot (Calidris canutus) exhibited seasonal alterations in mitochondrial volume (liver, pectoral muscle) and/or succinate dehydrogenase (SDH) activity (liver, pectoral muscle, heart, small intestine) during three distinct life-cycle stages: stable BM, spring peak in BM, and as BM rapidly declined after the spring peak. Mitochondrial volume in liver and pectoral muscle and SDH activity in liver and heart did not alter with life-cycle stage. However, red knot undergoing premigratory fattening exhibited significantly lower pectoral muscle SDH activity in concert with significantly elevated activity in the small intestine compared with the other two time-points, suggesting that tissue metabolic rate alters with life-cycle stage. The increased intestinal SDH activity may indicate an elevation in energy assimilation at a time when intestine hypertrophy occurs, thus maximizing BM increase prior to putative migration. The concomitant decrease in pectoral muscle activity may act to reduce overall metabolic rate, or at least help counter the elevation in intestinal mass-specific metabolic rate. Both tissues hypertrophy prior to migration in wild red knot, but hypertrophy of the intestine precedes that of pectoral muscle. Indeed, it appears that the intestinal mass undergoes atrophy by the time pectoral muscle hypertrophy occurs in wild red knot. Thus, physiological adjustments in tissue metabolism may be an important factor in the life-history strategies of migrating shorebirds.
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Affiliation(s)
- Colin Selman
- Department of Biological Sciences, Science Laboratories, University of Durham, Durham DH1 3LE, UK.
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34
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Glanville EJ, Seebacher F. Compensation for environmental change by complementary shifts of thermal sensitivity and thermoregulatory behaviour in an ectotherm. J Exp Biol 2006; 209:4869-77. [PMID: 17142675 DOI: 10.1242/jeb.02585] [Citation(s) in RCA: 108] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
SUMMARY
Thermoregulating animals are thought to have evolved a preferred body temperature at which thermally sensitive performance is optimised. Even during thermoregulation, however, many animals experience pronounced variability in body temperature, and may regulate to different body temperatures depending on environmental conditions. Here we test the hypothesis that there is a trade-off between regulating to lower body temperatures in cooler conditions and locomotory and metabolic performance. Animals (estuarine crocodiles, Crocodylus porosus) acclimated to cold (N=8) conditions had significantly lower maximum and mean daily body temperatures after 33 days than warm-acclimated animals (N=9), despite performing characteristic thermoregulatory behaviours. Concomitant with behavioural changes, maximum sustained swimming speed (Ucrit) shifted to the respective mean body temperatures during acclimation (cold=20°C, warm=29°C), but there was no difference in the maxima between acclimation groups. Mitochondrial oxygen consumption changed significantly during acclimation, and maximum respiratory control ratios coincided with mean body temperatures in liver, muscle and heart tissues. There were significant changes in the activities of regulatory metabolic enzymes (lactate dehydrogenase, citrate synthase, cytochrome c oxidase) and these were tissue specific. The extraordinary shift in behaviour and locomotory and metabolic performance shows that within individuals, behaviour and physiology covary to maximise performance in different environments.
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Affiliation(s)
- E J Glanville
- School of Biological Sciences A08, University of Sydney, NSW 2006, Australia
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35
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Savina MV, Emelyanova LV, Belyaeva EA. Bioenergetic parameters of lamprey and frog liver mitochondria during metabolic depression and activity. Comp Biochem Physiol B Biochem Mol Biol 2006. [DOI: https://doi.org/10.1016/j.cbpb.2006.07.011] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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36
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Savina MV, Emelyanova LV, Belyaeva EA. Bioenergetic parameters of lamprey and frog liver mitochondria during metabolic depression and activity. Comp Biochem Physiol B Biochem Mol Biol 2006; 145:296-305. [PMID: 17070716 DOI: 10.1016/j.cbpb.2006.07.011] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2005] [Revised: 05/16/2006] [Accepted: 07/31/2006] [Indexed: 02/08/2023]
Abstract
The objective of this study is to elucidate the role of mitochondria in reversible metabolic depression of hepatocytes of the Baltic lamprey (Lampetra fluviatilis) taking place in the last year of its life cycle and to compare their main bioenergetic parameters with those of the frog (Rana temporaria) and the white outbred mouse (Mus musculus). Using isolated mitochondria as a model, we have revealed significant seasonal variations in the main bioenergetic parameters of the lamprey liver. These changes indicate that the metabolic depression is mediated by prolonged reversible alterations of mitochondrial functions, which manifest in low activity of the mitochondrial respiratory chain, low oxidative phosphorylation, low content of mitochondrial adenine nucleotides, high level of reduced mitochondrial pyridine nucleotides and leaky mitochondrial membranes observed in winter. The enhanced ion membrane permeability of winter lamprey liver mitochondria is found to be sensitive to EGTA and to cyclosporine A in combination with ADP and Mg(2+) and is likely mediated opening the mitochondrial permeability transition pore in its low conductance state. The sharp activation of oxidation and phosphorylation in the lamprey liver mitochondria followed by spawning and death of the animal is observed in spring. The possible causes of the phenomenon and the differences obtained between lamprey, frog and mouse are under discussion.
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Affiliation(s)
- Margarita V Savina
- Laboratory of Comparative Biochemistry of Inorganic Ions, Sechenov Institute of Evolutionary Physiology and Biochemistry, Russian Academy of Sciences, Thorez pr. 44, 194223 St.-Petersburg, Russia.
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37
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Berner NJ, Bessay EP. Correlation of seasonal acclimatization in metabolic enzyme activity with preferred body temperature in the Eastern red spotted newt (Notophthalmus viridescens viridescens). Comp Biochem Physiol A Mol Integr Physiol 2006; 144:429-36. [PMID: 16716618 DOI: 10.1016/j.cbpa.2006.03.012] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2005] [Revised: 03/22/2006] [Accepted: 03/24/2006] [Indexed: 10/24/2022]
Abstract
Eastern red spotted newts, as aquatic adults, are active year round. They are small and easy to handle, and thus lent themselves to a laboratory study of seasonal changes in preferred body temperature and biochemical acclimatization. We collected newts in summer (n=20), late fall (n=10) and winter (n=5). Ten each of the summer and late fall newts were subjected to an aquatic thermal gradient. Summer newts maintained higher cloacal temperatures than late fall newts (26.8+/-0.5 degrees C and 17.2+/-0.4 degrees C, respectively). In addition, the activity of three muscle metabolic enzymes (cytochrome c oxidase (CCO), citrate synthase (CS) and lactate dehydrogenase (LDH)) was studied in all newts collected. Newts compensated for lower late fall and winter temperatures by increasing the activity of CCO during those seasons over that in summer newts at all assay temperatures (8, 16 and 26 degrees C). The activity of CS was greater in winter over summer newts at 8 and 16 degrees C. No seasonal differences in LDH activity were demonstrated. These data in newts indicate that this amphibian modifies some muscle metabolic enzymes in relation to seasonal changes and can modify its behavioral in a way that correlates with those biochemical changes.
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Affiliation(s)
- Nancy J Berner
- Department of Biology, University of the South, Sewanee, TN, USA.
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38
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Angilletta MJ, Bennett AF, Guderley H, Navas CA, Seebacher F, Wilson RS. Coadaptation: A Unifying Principle in Evolutionary Thermal Biology. Physiol Biochem Zool 2006; 79:282-94. [PMID: 16555188 DOI: 10.1086/499990] [Citation(s) in RCA: 199] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/25/2005] [Indexed: 11/03/2022]
Abstract
Over the last 50 yr, thermal biology has shifted from a largely physiological science to a more integrated science of behavior, physiology, ecology, and evolution. Today, the mechanisms that underlie responses to environmental temperature are being scrutinized at levels ranging from genes to organisms. From these investigations, a theory of thermal adaptation has emerged that describes the evolution of thermoregulation, thermal sensitivity, and thermal acclimation. We review and integrate current models to form a conceptual model of coadaptation. We argue that major advances will require a quantitative theory of coadaptation that predicts which strategies should evolve in specific thermal environments. Simply combining current models, however, is insufficient to understand the responses of organisms to thermal heterogeneity; a theory of coadaptation must also consider the biotic interactions that influence the net benefits of behavioral and physiological strategies. Such a theory will be challenging to develop because each organism's perception of and response to thermal heterogeneity depends on its size, mobility, and life span. Despite the challenges facing thermal biologists, we have never been more pressed to explain the diversity of strategies that organisms use to cope with thermal heterogeneity and to predict the consequences of thermal change for the diversity of communities.
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Affiliation(s)
- Michael J Angilletta
- Department of Ecology and Organismal Biology, Indiana State University, Terre Haute, Indiana 47809, USA.
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39
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Stuart JA, Brown MF. Energy, quiescence and the cellular basis of animal life spans. Comp Biochem Physiol A Mol Integr Physiol 2006; 143:12-23. [PMID: 16377223 DOI: 10.1016/j.cbpa.2005.11.002] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2005] [Revised: 11/02/2005] [Accepted: 11/03/2005] [Indexed: 01/11/2023]
Abstract
Animals are routinely faced with harsh environmental conditions in which insufficient energy is available to grow and reproduce. Many animals adapt to this challenge by entering a dormant, or quiescent state. In some animals, such as the nematode Caenorhabditis elegans, quiescence is coincident with increased stress resistance and longevity. Here we review evidence that the rules of life span extension established in C. elegans may be generally true of most animals. That is, that the rate of animal aging correlates inversely with cellular resistance to physiological stress, particularly oxidative stress, and that stress resistance is co-regulated with the quiescence adaptation (where the latter occurs). We discuss evidence for highly conserved intracellular signalling pathways involved in energy sensing that are sensitive to aspects of mitochondrial energy transduction and can be modulated in response to energetic flux. We provide a broad overview of the current knowledge of the relationships between energy, metabolism and life span.
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Affiliation(s)
- Jeffrey A Stuart
- Department of Biological Sciences, Brock University, St. Catharines, Ontario, Canada L2S 3A1.
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40
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Seebacher F. A review of thermoregulation and physiological performance in reptiles: what is the role of phenotypic flexibility? J Comp Physiol B 2005; 175:453-61. [PMID: 16034580 DOI: 10.1007/s00360-005-0010-6] [Citation(s) in RCA: 94] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2005] [Revised: 04/29/2005] [Accepted: 05/24/2005] [Indexed: 10/25/2022]
Abstract
Biological functions are dependent on the temperature of the organism. Animals may respond to fluctuation in the thermal environment by regulating their body temperature and by modifying physiological and biochemical rates. Phenotypic flexibility (reversible phenotypic plasticity, acclimation, or acclimatisation in rate functions occurs in all major taxonomic groups and may be considered as an ancestral condition. Within the Reptilia, representatives from all major groups show phenotypic flexibility in response to long-term or chronic changes in the thermal environment. Acclimation or acclimatisation in reptiles are most commonly assessed by measuring whole animal responses such as oxygen consumption, but whole animal responses are comprised of variation in individual traits such as enzyme activities, hormone expression, and cardiovascular functions. The challenge now lies in connecting the changes in the components to the functioning of the whole animal and its fitness. Experimental designs in research on reptilian thermal physiology should incorporate the capacity for reversible phenotypic plasticity as a null-hypothesis, because the significance of differential body temperature-performance relationships (thermal reaction norms) between individuals, populations, or species cannot be assessed without testing that null-hypothesis.
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Affiliation(s)
- Frank Seebacher
- Integrative Physiology, School of Biological Sciences A08, The University of Sydney, NSW 2006, Australia.
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41
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Abstract
For most fish, body temperature is very close to that of the habitat. The diversity of thermal habitats exploited by fish as well as their capacity to adapt to thermal change makes them excellent organisms in which to examine the evolutionary and phenotypic responses to temperature. An extensive literature links cold temperatures with enhanced oxidative capacities in fish tissues, particularly skeletal muscle. Closer examination of inter-species comparisons (i.e. the evolutionary perspective) indicates that the proportion of muscle fibres occupied by mitochondria increases at low temperatures, most clearly in moderately active demersal species. Isolated muscle mitochondria show no compensation of protein-specific rates of substrate oxidation during evolutionary adaptation to cold temperatures. During phenotypic cold acclimation, mitochondrial volume density increases in oxidative muscle of some species (striped bass Morone saxatilis, crucian carp Carassius carassius), but remains stable in others (rainbow trout Oncorhynchus mykiss). A role for the mitochondrial reticulum in distributing oxygen through the complex architecture of skeletal muscle fibres may explain mitochondrial proliferation. In rainbow trout, compensatory increases in the protein-specific rates of mitochondrial substrate oxidation maintain constant capacities except at winter extremes. Changes in mitochondrial properties (membrane phospholipids, enzymatic complement and cristae densities) can enhance the oxidative capacity of muscle in the absence of changes in mitochondrial volume density. Changes in the unsaturation of membrane phospholipids are a direct response to temperature and occur in isolated cells. This fundamental response maintains the dynamic phase behaviour of the membrane and adjusts the rates of membrane processes. However, these adjustments may have deleterious consequences. For fish living at low temperatures, the increased polyunsaturation of mitochondrial membranes should raise rates of mitochondrial respiration which would in turn enhance the formation of reactive oxygen species (ROS), increase proton leak and favour peroxidation of these membranes. Minimisation of mitochondrial oxidative capacities in organisms living at low temperatures would reduce such damage.
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Affiliation(s)
- Helga Guderley
- Département de biologie, Université Laval, Québec, P.Q. Canada G1K 7P4
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42
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Seebacher F, Guderley H, Elsey RM, Trosclair PL. Seasonal acclimatisation of muscle metabolic enzymes in a reptile (Alligator mississippiensis). J Exp Biol 2003; 206:1193-200. [PMID: 12604579 DOI: 10.1242/jeb.00223] [Citation(s) in RCA: 103] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Reptiles living in heterogeneous thermal environments are often thought to show behavioural thermoregulation or to become inactive when environmental conditions prevent the achievement of preferred body temperatures. By contrast, thermally homogeneous environments preclude behavioural thermoregulation, and ectotherms inhabiting these environments (particularly fish in which branchial respiration requires body temperature to follow water temperature) modify their biochemical capacities in response to long-term seasonal temperature fluctuations. Reptiles may also be active at seasonally varying body temperatures and could, therefore, gain selective advantages from regulating biochemical capacities. Hence, we tested the hypothesis that a reptile (the American alligator Alligator mississippiensis) that experiences pronounced seasonal fluctuations in body temperature will show seasonal acclimatisation in the activity of its metabolic enzymes. We measured body temperatures of alligators in the wild in winter and summer (N=7 alligators in each season), and we collected muscle samples from wild alligators (N=31 in each season) for analysis of metabolic enzyme activity (lactate dehydrogenase, citrate synthase and cytochrome c oxidase). There were significant differences in mean daily body temperatures between winter (15.66+/-0.43 degrees C; mean +/- S.E.M.) and summer (29.34+/-0.21 degrees C), and daily body temperatures fluctuated significantly more in winter compared with summer. Alligators compensated for lower winter temperatures by increasing enzyme activities, and the activities of cytochrome c oxidase and lactate dehydrogenase were significantly greater in winter compared with summer at all assay temperatures. The activity of citrate synthase was significantly greater in the winter samples at the winter body temperature (15 degrees C) but not at the summer body temperature (30 degrees C). The thermal sensitivity (Q(10)) of mitochondrial enzymes decreased significantly in winter compared with in summer. The activity of mitochondrial enzymes was significantly greater in males than in females, but there were no differences between sexes for lactate dehydrogenase activity. The differences between sexes could be the result of the sex-specific seasonal demands for locomotor performance. Our data indicate that biochemical acclimatisation is important in thermoregulation of reptiles and that it is not sufficient to base conclusions about their thermoregulatory ability entirely on behavioural patterns.
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Affiliation(s)
- Frank Seebacher
- School of Biological Sciences A08, University of Sydney, New South Wales 2006, Australia.
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43
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Boutilier RG, St-Pierre J. Adaptive plasticity of skeletal muscle energetics in hibernating frogs:mitochondrial proton leak during metabolic depression. J Exp Biol 2002; 205:2287-96. [PMID: 12110662 DOI: 10.1242/jeb.205.15.2287] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
SUMMARYThe common frog (Rana temporaria) spends the coldest months of each year overwintering in ice-covered ponds where temperatures can vary from 0.5 to 4.0°C. Over the course of a winter season, the animals enter progressively into a state of metabolic depression that relies almost exclusively on aerobic production of ATP. However, if aerobic metabolism is threatened, for example by increasingly hypoxic conditions, decreases in the animal's metabolic rate can reach upwards of 75% compared with the 50%decrease seen during normoxia. Under these conditions, the major proportion of the overall reduction in whole-animal metabolic rate can be accounted for by metabolic suppression of the skeletal muscle (which makes up approximately 40%of body mass). Little is known about the properties of mitochondria during prolonged periods of metabolic depression, so we have examined several aspects of mitochondrial metabolism in the skeletal muscle of frogs over periods of hibernation of up to 4 months. Mitochondria isolated from the skeletal muscle of frogs hibernating in hypoxic water show a considerable reorganisation of function compared with those isolated from normoxic submerged animals at the same temperature (3°C). Both the active (state 3) and resting (state 4)respiration rates of mitochondria decrease during hypoxic, but not normoxic,hibernation. In addition, the affinity of mitochondria for oxygen increases during periods of acute hypoxic stress during normoxic hibernation as well as during long-term hibernation in hypoxic water. The decrease in mitochondrial state 4 respiration rates during hypoxic hibernation evidently occurs through a reduction in electron-transport chain activity, not through a lowered proton conductance of the mitochondrial inner membrane. The reduced aerobic capacity of frog skeletal muscle during hypoxic hibernation is accompanied by lowered activities of key enzymes of mitochondrial metabolism caused by changes in the intrinsic properties of the mitochondria. In the absence of oxygen, the mitochondrial F1Fo-ATPase (the ATP synthase) begins to run backwards as it actively pumps protons from the matrix in an attempt to maintain the mitochondrial membrane potential. At this time, the ATP synthase functions as an ATPase to preserve a certain proton-motive force. Frogs limit ATP wastage during anoxia by a profound inhibition of the ATP synthase. Taken together, our studies show that protonmotive force is lowered aerobically by restricting electron supply and during anoxia by restricting mitochondrial ATPase activity.
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Affiliation(s)
- Robert G Boutilier
- Department of Zoology, Downing Street, University of Cambridge, Cambridge CB2 3EJ, UK.
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Guderley H, St-Pierre J. Going with the flow or life in the fast lane: contrasting mitochondrial responses to thermal change. J Exp Biol 2002; 205:2237-49. [PMID: 12110658 DOI: 10.1242/jeb.205.15.2237] [Citation(s) in RCA: 115] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
SUMMARYTemperature is one of the most important environmental factors affecting the physiology of animals. Seasonal fluctuations in temperature are of particular importance in aquatic ectotherms since their body temperature is in equilibrium with their environment. When an organism faces adverse environmental conditions, it can either remain active or enter into metabolic depression, adopting the strategy that maximises its fitness. Physiological responses to environmental stress occur at many different levels of organisation in an animal. Here, we focus on mitochondria, given their central importance in cellular energy metabolism. We contrast the thermal biology of skeletal muscle mitochondria from cold-active species with that of species that spend their winters in a metabolically depressed state. Specifically, we examine the modifications of mitochondrial properties during thermal/seasonal acclimation and examine mechanisms by which these modifications can arise. While compensatory responses to cold acclimation include increases in mitochondrial abundance, in the oxidative capacities of individual mitochondria and adjustments of ADP affinities, metabolic depression can reduce tissue levels of mitochondrial enzymes and mitochondrial proton leak rates.
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Affiliation(s)
- Helga Guderley
- Département de Biologie, Université Laval, Québec, P.Q., Canada G1T 2M7.
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45
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Bishop T, Ocloo A, Brand MD. Structure and function of mitochondria in hepatopancreas cells from metabolically depressed snails. Physiol Biochem Zool 2002; 75:134-44. [PMID: 12024289 DOI: 10.1086/340852] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/08/2002] [Indexed: 11/03/2022]
Abstract
Mitochondria in cells isolated from the hepatopancreas of aestivating land snails (Helix aspersa) consume oxygen at 30% of the active control rate. The aim of this study was to investigate whether the lower respiration rate is caused by a decrease in the density of mitochondria or by intrinsic changes in the mitochondria. Mitochondria occupied 2% of cellular volume, and the mitochondrial inner membrane surface density was 17 microm(-1), in cells from active snails. These values were not different in cells from aestivating snails. The mitochondrial protein and mitochondrial phospholipid contents of cells were also similar. There was little difference in the phospholipid fatty acyl composition of mitochondria isolated from metabolically depressed or active snails, except for arachidonic acid, which was 18% higher in mitochondria from aestivating snails. However, the activities of citrate synthase and cytochrome c oxidase in mitochondria isolated from aestivating snails were 68% and 63% of control, respectively. Thus the lower mitochondrial respiration rate in hepatopancreas cells from aestivating snails was not caused by differences in mitochondrial volume or surface density but was associated with intrinsic changes in the mitochondria.
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Affiliation(s)
- T Bishop
- Medical Research Council, Dunn Human Nutrition Unit, Hills Road, Cambridge CB2 2XY, United Kingdom.
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46
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Bishop T, St-Pierre J, Brand MD. Primary causes of decreased mitochondrial oxygen consumption during metabolic depression in snail cells. Am J Physiol Regul Integr Comp Physiol 2002; 282:R372-82. [PMID: 11792646 DOI: 10.1152/ajpregu.00401.2001] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Cells isolated from the hepatopancreas of estivating snails (Helix aspersa) have strongly depressed mitochondrial respiration compared with controls. Mitochondrial respiration was divided into substrate oxidation (which produces the mitochondrial membrane potential) and ATP turnover and proton leak (which consume it). The activity of substrate oxidation (and probably ATP turnover) decreased, whereas the activity of proton leak remained constant in estivation. These primary changes resulted in a lower mitochondrial membrane potential in hepatopancreas cells from estivating compared with active snails, leading to secondary decreases in respiration to drive ATP turnover and proton leak. The respiration to drive ATP turnover and proton leak decreased in proportion to the overall decrease in mitochondrial respiration, so that the amount of ATP turned over per O2 consumed remained relatively constant and aerobic efficiency was maintained in this hypometabolic state. At least 75% of the total response of mitochondrial respiration to estivation was caused by primary changes in the kinetics of substrate oxidation, with only 25% or less of the response occurring through primary effects on ATP turnover.
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Affiliation(s)
- Tammie Bishop
- Medical Research Council, Dunn Human Nutrition Unit, Cambridge CB2 2XY, United Kingdom.
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