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Chokesuwattanaskul S, Fresneda Alarcon M, Mangalakumaran S, Grosman R, Cross AL, Chapman EA, Mason D, Moots RJ, Phelan MM, Wright HL. Metabolic Profiling of Rheumatoid Arthritis Neutrophils Reveals Altered Energy Metabolism That Is Not Affected by JAK Inhibition. Metabolites 2022; 12:650. [PMID: 35888774 PMCID: PMC9321732 DOI: 10.3390/metabo12070650] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2022] [Revised: 07/06/2022] [Accepted: 07/11/2022] [Indexed: 02/05/2023] Open
Abstract
Neutrophils play a key role in the pathophysiology of rheumatoid arthritis (RA) where release of ROS and proteases directly causes damage to joints and tissues. Neutrophil function can be modulated by Janus Kinase (JAK) inhibitor drugs, including tofacitinib and baricitinib, which are clinically effective treatments for RA. However, clinical trials have reported increased infection rates and transient neutropenia during therapy. The subtle differences in the mode of action, efficacy and safety of JAK inhibitors have been the primary research topic of many clinical trials and systematic reviews, to provide a more precise and targeted treatment to patients. The aim of this study was to determine both the differences in the metabolome of neutrophils from healthy controls and people with RA, and the effect of different JAK inhibitors on the metabolome of healthy and RA neutrophils. Isolated neutrophils from healthy controls (HC) (n = 6) and people with RA (n = 7) were incubated with baricitinib, tofacitinib or a pan-JAK inhibitor (all 200 ng/mL) for 2 h. Metabolites were extracted, and 1H nuclear magnetic resonance (NMR) was applied to study the metabolic changes. Multivariate analyses and machine learning models showed a divergent metabolic pattern in RA neutrophils compared to HC at 0 h (F1 score = 86.7%) driven by energy metabolites (ATP, ADP, GTP and glucose). No difference was observed in the neutrophil metabolome when treated with JAK inhibitors. However, JAK inhibitors significantly inhibited ROS production and baricitinib decreased NET production (p < 0.05). Bacterial killing was not impaired by JAK inhibitors, indicating that the effect of JAK inhibitors on neutrophils can inhibit joint damage in RA without impairing host defence. This study highlights altered energy metabolism in RA neutrophils which may explain the cause of their dysregulation in inflammatory disease.
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Affiliation(s)
| | - Michele Fresneda Alarcon
- Department of Musculoskeletal and Ageing Science, Institute of Life Course and Medical Sciences, University of Liverpool, Liverpool L7 8TX, UK; (M.F.A.); (A.L.C.); (E.A.C.)
| | | | - Rudi Grosman
- Institute of Systems, Molecular and Integrative Biology, University of Liverpool, Liverpool L69 7BE, UK; (R.G.); (M.M.P.)
- High Field NMR Facility, Liverpool Shared Research Facilities University of Liverpool, Liverpool L69 7TX, UK
| | - Andrew L. Cross
- Department of Musculoskeletal and Ageing Science, Institute of Life Course and Medical Sciences, University of Liverpool, Liverpool L7 8TX, UK; (M.F.A.); (A.L.C.); (E.A.C.)
| | - Elinor A. Chapman
- Department of Musculoskeletal and Ageing Science, Institute of Life Course and Medical Sciences, University of Liverpool, Liverpool L7 8TX, UK; (M.F.A.); (A.L.C.); (E.A.C.)
| | - David Mason
- Centre for Cell Imaging, Institute of Integrative Biology, University of Liverpool, Liverpool L69 7TX, UK;
| | - Robert J. Moots
- Department of Rheumatology, Aintree University Hospital, Liverpool L9 7AL, UK;
- Faculty of Health, Social Care and Medicine, Edge Hill University, Ormskirk L39 4QP, UK
| | - Marie M. Phelan
- Institute of Systems, Molecular and Integrative Biology, University of Liverpool, Liverpool L69 7BE, UK; (R.G.); (M.M.P.)
- High Field NMR Facility, Liverpool Shared Research Facilities University of Liverpool, Liverpool L69 7TX, UK
| | - Helen L. Wright
- Department of Musculoskeletal and Ageing Science, Institute of Life Course and Medical Sciences, University of Liverpool, Liverpool L7 8TX, UK; (M.F.A.); (A.L.C.); (E.A.C.)
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Wright HL, Lyon M, Chapman EA, Moots RJ, Edwards SW. Rheumatoid Arthritis Synovial Fluid Neutrophils Drive Inflammation Through Production of Chemokines, Reactive Oxygen Species, and Neutrophil Extracellular Traps. Front Immunol 2021; 11:584116. [PMID: 33469455 PMCID: PMC7813679 DOI: 10.3389/fimmu.2020.584116] [Citation(s) in RCA: 60] [Impact Index Per Article: 20.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2020] [Accepted: 11/20/2020] [Indexed: 12/14/2022] Open
Abstract
Rheumatoid arthritis (RA) is a chronic inflammatory disorder affecting synovial joints. Neutrophils are believed to play an important role in both the initiation and progression of RA, and large numbers of activated neutrophils are found within both synovial fluid (SF) and synovial tissue from RA joints. In this study we analyzed paired blood and SF neutrophils from patients with severe, active RA (DAS28>5.1, n=3) using RNA-seq. 772 genes were significantly different between blood and SF neutrophils. IPA analysis predicted that SF neutrophils had increased expression of chemokines and ROS production, delayed apoptosis, and activation of signaling cascades regulating the production of NETs. This activated phenotype was confirmed experimentally by incubating healthy control neutrophils in cell-free RA SF, which was able to delay apoptosis and induce ROS production in both unprimed and TNFα primed neutrophils (p<0.05). RA SF significantly increased neutrophil migration through 3μM transwell chambers (p<0.05) and also increased production of NETs by healthy control neutrophils (p<0.001), including exposure of myeloperoxidase (MPO) and citrullinated histone-H3-positive DNA NETs. IPA analysis predicted NET production was mediated by signaling networks including AKT, RAF1, SRC, and NF-κB. Our results expand the understanding of the molecular changes that take place in the neutrophil transcriptome during migration into inflamed joints in RA, and the altered phenotype in RA SF neutrophils. Specifically, RA SF neutrophils lose their migratory properties, residing within the joint to generate signals that promote joint damage, as well as inflammation via recruitment and activation of both innate and adaptive immune cells. We propose that this activated SF neutrophil phenotype contributes to the chronic inflammation and progressive damage to cartilage and bone observed in patients with RA.
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Affiliation(s)
- Helen L. Wright
- Institute of Life Course and Medical Sciences, University of Liverpool, Liverpool, United Kingdom
| | - Max Lyon
- Institute of Life Course and Medical Sciences, University of Liverpool, Liverpool, United Kingdom
| | - Elinor A. Chapman
- Institute of Life Course and Medical Sciences, University of Liverpool, Liverpool, United Kingdom
| | - Robert J. Moots
- Department of Rheumatology, Aintree University Hospital, Liverpool, United Kingdom
- Faculty of Health, Social Care and Medicine, Edge Hill University, Ormskirk, United Kingdom
| | - Steven W. Edwards
- Faculty of Health, Social Care and Medicine, Edge Hill University, Ormskirk, United Kingdom
- Institute of Infection, Veterinary and Ecological Sciences, University of Liverpool, Liverpool, United Kingdom
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Aggarwal P, Baker J, Boyd MT, Coyle S, Probert C, Chapman EA. Optimisation of Urine Sample Preparation for Headspace-Solid Phase Microextraction Gas Chromatography-Mass Spectrometry: Altering Sample pH, Sulphuric Acid Concentration and Phase Ratio. Metabolites 2020; 10:metabo10120482. [PMID: 33255680 PMCID: PMC7760603 DOI: 10.3390/metabo10120482] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2020] [Revised: 11/17/2020] [Accepted: 11/17/2020] [Indexed: 12/21/2022] Open
Abstract
Headspace-solid phase microextraction gas chromatography-mass spectrometry (HS-SPME-GC-MS) can be used to measure volatile organic compounds (VOCs) in human urine. However, there is no widely adopted standardised protocol for the preparation of urine samples for analysis resulting in an inability to compare studies reliably between laboratories. This paper investigated the effect of altering urine sample pH, volume, and vial size for optimising detection of VOCs when using HS-SPME-GC-MS. This is the first, direct comparison of H2SO4, HCl, and NaOH as treatment techniques prior to HS-SPME-GC-MS analysis. Altering urine sample pH indicates that H2SO4 is more effective at optimising detection of VOCs than HCl or NaOH. H2SO4 resulted in a significantly larger mean number of VOCs being identified per sample (on average, 33.5 VOCs to 24.3 in HCl or 12.2 in NaOH treated urine) and more unique VOCs, produced a more diverse range of classes of VOCs, and led to less HS-SPME-GC-MS degradation. We propose that adding 0.2 mL of 2.5 M H2SO4 to 1 mL of urine within a 10 mL headspace vial is the optimal sample preparation prior to HS-SPME-GC-MS analysis. We hope the use of our optimised method for urinary HS-SPME-GC-MS analysis will enhance our understanding of human disease and bolster metabolic biomarker identification.
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Affiliation(s)
- Prashant Aggarwal
- Department of Molecular and Clinical Cancer Medicine, Institute of Systems, Molecular and Integrative Biology, University of Liverpool, Liverpool L69 3BX, UK; (P.A.); (J.B.); (C.P.)
- School of Medicine, Cedar House, University of Liverpool, Liverpool L69 3GE, UK
| | - James Baker
- Department of Molecular and Clinical Cancer Medicine, Institute of Systems, Molecular and Integrative Biology, University of Liverpool, Liverpool L69 3BX, UK; (P.A.); (J.B.); (C.P.)
- School of Medicine, Cedar House, University of Liverpool, Liverpool L69 3GE, UK
| | - Mark T. Boyd
- Department of Molecular and Clinical Cancer Medicine, Institute of Systems, Molecular and Integrative Biology, Cancer Research Centre, University of Liverpool, Liverpool L3 9TA, UK;
| | - Séamus Coyle
- Palliative Care Institute Liverpool, Cancer Research Centre, University of Liverpool, Liverpool L3 9TA, UK;
- Clatterbridge Cancer Centre, Liverpool L7 8YA, UK
| | - Chris Probert
- Department of Molecular and Clinical Cancer Medicine, Institute of Systems, Molecular and Integrative Biology, University of Liverpool, Liverpool L69 3BX, UK; (P.A.); (J.B.); (C.P.)
| | - Elinor A. Chapman
- Department of Molecular and Clinical Cancer Medicine, Institute of Systems, Molecular and Integrative Biology, University of Liverpool, Liverpool L69 3BX, UK; (P.A.); (J.B.); (C.P.)
- Palliative Care Institute Liverpool, Cancer Research Centre, University of Liverpool, Liverpool L3 9TA, UK;
- School of Medical Sciences, Bangor University, Bangor, Gwynedd LL57 2DG, UK
- Correspondence:
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Chapman EA, Lyon M, Simpson D, Mason D, Beynon RJ, Moots RJ, Wright HL. 012 Proteomic analysis of neutrophil extracellular traps in rheumatoid arthritis and systemic lupus erythematosus. Rheumatology (Oxford) 2019. [DOI: 10.1093/rheumatology/kez106.011] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Elinor A Chapman
- Musculoskeletal Biology 1, University of Liverpool, Liverpool, UNITED KINGDOM
| | - Max Lyon
- Musculoskeletal Biology 1, University of Liverpool, Liverpool, UNITED KINGDOM
| | - Deborah Simpson
- Centre for Proteome Research, University of Liverpool, Liverpool, UNITED KINGDOM
| | - David Mason
- Centre for Cell Imaging, University of Liverpool, Liverpool, UNITED KINGDOM
| | - Robert J Beynon
- Centre for Proteome Research, University of Liverpool, Liverpool, UNITED KINGDOM
| | - Robert J Moots
- Musculoskeletal Biology 1, University of Liverpool, Liverpool, UNITED KINGDOM
| | - Helen L Wright
- Musculoskeletal Biology 1, University of Liverpool, Liverpool, UNITED KINGDOM
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Chapman EA, Lyon M, Simpson D, Mason D, Beynon RJ, Moots RJ, Wright HL. Caught in a Trap? Proteomic Analysis of Neutrophil Extracellular Traps in Rheumatoid Arthritis and Systemic Lupus Erythematosus. Front Immunol 2019; 10:423. [PMID: 30915077 PMCID: PMC6421309 DOI: 10.3389/fimmu.2019.00423] [Citation(s) in RCA: 111] [Impact Index Per Article: 22.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2018] [Accepted: 02/18/2019] [Indexed: 12/22/2022] Open
Abstract
Neutrophil Extracellular Traps (NETs) are implicated in the development of auto-immunity in diseases such as rheumatoid arthritis (RA) and systemic lupus erythematosus (SLE) through the externalization of intracellular neoepitopes e.g., dsDNA and nuclear proteins in SLE and citrullinated peptides in RA. The aim of this work was to use quantitative proteomics to identify and measure NET proteins produced by neutrophils from healthy controls, and from patients with RA and SLE to determine if NETs can be differentially-generated to expose different sets of neoepitopes. Ultra-pure neutrophils (>99%) from healthy individuals (n = 3) and patients with RA or SLE (n = 6 each) were incubated ± PMA (50 nM, PKC super-activator) or A23187 (3.8 μM, calcium ionophore) for 4 h. NETs were liberated by nuclease digestion and concentrated onto Strataclean beads prior to on-bead digestion with trypsin. Data-dependent LC-MS/MS analyses were conducted on a QExactive HF quadrupole-Orbitrap mass spectrometer, and label-free protein quantification was carried out using Progenesis QI. PMA-induced NETs were decorated with annexins, azurocidin and histone H3, whereas A23187-induced NETs were decorated with granule proteins including CAMP/LL37, CRISP3, lipocalin and MMP8, histones H1.0, H1.4, and H1.5, interleukin-8, protein-arginine deiminase-4 (PADI4), and α-enolase. Four proteins were significantly different between PMA-NETs from RA and SLE neutrophils (p < 0.05): RNASE2 was higher in RA, whereas MPO, leukocyte elastase inhibitor and thymidine phosphorylase were higher in SLE. For A23187-NETs, six NET proteins were higher in RA (p < 0.05), including CAMP/LL37, CRISP3, interleukin-8, MMP8; Thirteen proteins were higher in SLE, including histones H1.0, H2B, and H4. This work provides the first, direct comparison of NOX2-dependent (PMA) and NOX2-independent (A23187) NETs using quantitative proteomics, and the first direct comparison of RA and SLE NETs using quantitative proteomics. We show that it is the nature of the stimulant rather than neutrophil physiology that determines NET protein profiles in disease, since stimulation of NETosis in either a NOX2-dependent or a NOX2-independent manner generates broadly similar NET proteins irrespective of the disease background. We also use our proteomics pipeline to identify an extensive range of post-translationally modified proteins in RA and SLE, including histones and granule proteins, many of which are known targets of auto-antibodies in each disease.
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Affiliation(s)
- Elinor A Chapman
- Department of Musculoskeletal Biology I, Institute of Ageing and Chronic Disease, University of Liverpool, Liverpool, United Kingdom
| | - Max Lyon
- Department of Musculoskeletal Biology I, Institute of Ageing and Chronic Disease, University of Liverpool, Liverpool, United Kingdom
| | - Deborah Simpson
- Department of Biochemistry, Institute of Integrative Biology, University of Liverpool, Liverpool, United Kingdom.,Centre for Proteome Research, University of Liverpool, Liverpool, United Kingdom
| | - David Mason
- Department of Biochemistry, Institute of Integrative Biology, University of Liverpool, Liverpool, United Kingdom.,Centre for Cell Imaging, University of Liverpool, Liverpool, United Kingdom
| | - Robert J Beynon
- Department of Biochemistry, Institute of Integrative Biology, University of Liverpool, Liverpool, United Kingdom.,Centre for Proteome Research, University of Liverpool, Liverpool, United Kingdom
| | - Robert J Moots
- Department of Musculoskeletal Biology I, Institute of Ageing and Chronic Disease, University of Liverpool, Liverpool, United Kingdom.,University of Liverpool and Aintree University Hospital, Members of Liverpool Health Partners, Liverpool, United Kingdom
| | - Helen L Wright
- Department of Musculoskeletal Biology I, Institute of Ageing and Chronic Disease, University of Liverpool, Liverpool, United Kingdom
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Glennon-Alty L, Hackett AP, Chapman EA, Wright HL. Neutrophils and redox stress in the pathogenesis of autoimmune disease. Free Radic Biol Med 2018; 125:25-35. [PMID: 29605448 DOI: 10.1016/j.freeradbiomed.2018.03.049] [Citation(s) in RCA: 92] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/08/2017] [Revised: 03/22/2018] [Accepted: 03/28/2018] [Indexed: 12/18/2022]
Abstract
Polymorphonuclear leukocytes, or neutrophils, are specialist phagocytic cells of the innate immune system. Their primary role is host defence against micro-organisms, which they kill via phagocytosis, followed by release of reactive oxygen species (ROS) and proteolytic enzymes within the phagosome. ROS are generated via the action of the NADPH oxidase (also known as NOX2), in a process termed the 'Respiratory Burst'. This process consumes large amounts of oxygen, which is converted into the highly-reactive superoxide radical O2- and H2O2. Subsequent activation of myeloperoxidase (MPO) generates secondary oxidants and chloroamines that are highly microbiocidal in nature, which together with proteases such as elastase and gelatinase provide a toxic intra-phagosomal environment able to kill a broad range of micro-organisms. However, under certain circumstances such as during an auto-immune response, neutrophils can be triggered to release ROS and proteases extracellularly causing damage to host tissues, modification of host proteins, lipids and DNA and dysregulation of oxidative homeostasis. This review describes the range of ROS species produced by human neutrophils with a focus on the implications of neutrophil redox products in autoimmune inflammation.
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Affiliation(s)
- Laurence Glennon-Alty
- Department of Musculoskeletal Biology, Institute of Ageing and Chronic Disease, University of Liverpool, 6 West Derby Street, L7 8TX Liverpool, UK; Liverpool Health Partners, University of Liverpool, Liverpool, UK
| | - Angela P Hackett
- Department of Musculoskeletal Biology, Institute of Ageing and Chronic Disease, University of Liverpool, 6 West Derby Street, L7 8TX Liverpool, UK
| | - Elinor A Chapman
- Department of Musculoskeletal Biology, Institute of Ageing and Chronic Disease, University of Liverpool, 6 West Derby Street, L7 8TX Liverpool, UK
| | - Helen L Wright
- Department of Musculoskeletal Biology, Institute of Ageing and Chronic Disease, University of Liverpool, 6 West Derby Street, L7 8TX Liverpool, UK.
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Lyon MA, Chapman EA, Moots RJ, Wright HL. 249 Rheumatoid arthritis neutrophil extra-cellular traps contain citrullinated histone-H3. Rheumatology (Oxford) 2018. [DOI: 10.1093/rheumatology/key075.473] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Max A Lyon
- Institute of Ageing and Chronic Disease, University of Liverpool, Liverpool, UNITED KINGDOM
| | - Elinor A Chapman
- Institute of Ageing and Chronic Disease, University of Liverpool, Liverpool, UNITED KINGDOM
| | - Robert J Moots
- Institute of Ageing and Chronic Disease, University of Liverpool, Liverpool, UNITED KINGDOM
| | - Helen L Wright
- Institute of Ageing and Chronic Disease, University of Liverpool, Liverpool, UNITED KINGDOM
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Holmes K, Williams CM, Chapman EA, Cross MJ. Detection of siRNA induced mRNA silencing by RT-qPCR: considerations for experimental design. BMC Res Notes 2010; 3:53. [PMID: 20199660 PMCID: PMC2850347 DOI: 10.1186/1756-0500-3-53] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2010] [Accepted: 03/03/2010] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND RNA interference (RNAi) has been one of the most rapidly expanding areas of biological research in the past decade, revolutionizing the ability to analyze gene function. Thorough validation of siRNA duplexes is required prior to use in experimental systems, ideally by western blotting to show a reduction in protein levels. However, in many cases good antibodies are not available, and researchers must rely on RT-qPCR to detect knockdown of the mRNA species. FINDINGS We have observed a phenomenon that gives a disparity between analyzing small interfering RNA (siRNA) efficacy by western blotting of the protein levels and real-time quantitative PCR (RT-qPCR) measurement of mRNA levels. Detection of this phenomenon was dependent upon the location of the target amplicon for PCR primers within the mRNA. CONCLUSIONS Our data suggests that for certain mRNAs, degradation of the 3' mRNA fragment resulting from siRNA mediated cleavage is blocked, leaving an mRNA fragment that can act as a template for cDNA synthesis, giving rise to false negative results and the rejection of a valid siRNA duplex. We show that this phenomenon may be avoided by the careful design of RT-qPCR primers for each individual siRNA experiment.
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Affiliation(s)
- Katherine Holmes
- Department of Pharmacology and Therapeutics, School of Biomedical Sciences, University of Liverpool, Liverpool, L69 3GE, UK.
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Raison JK, Chapman EA, White PY. Wheat mitochondria: oxidative activity and membrane lipid structure as a function of temperature. Plant Physiol 1977; 59:623-7. [PMID: 16659906 PMCID: PMC542461 DOI: 10.1104/pp.59.4.623] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
Mitochondrial oxidative activity and membrane lipid structure of two wheat (Triticum aestivum L.) cultivars were measured as a function of temperature. The Arrhenius activation energy for the oxidation of both succinate and alpha-ketoglutarate was constant over the temperature range of 3 to 27 C. The activation energy for succinate-cytochrome c oxidoreductase activity was also constant over the same temperature range. The concentration of mitochondria in the reaction, the degree of initial inhibition of state 3 respiration, and the time after isolation of mitochondria were each shown to be capable of causing a disproportionate decrease in the rate of oxidation at low temperatures which resulted in an apparent increase in the activation energy of oxidative activity. Using three spin-labeling techniques, wheat membrane lipids were shown to undergo phase changes at about 0 C and 30 C. It is concluded that the membrane lipids of wheat, a chillingresistant plant, undergo a phase transition similar to the transition observed in the membrane lipids of chilling-sensitive plants. For wheat, however, the transition is initiated at a lower temperature and extends over a wider temperature range.
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Affiliation(s)
- J K Raison
- Plant Physiology Unit, CSIRO Division of Food Research and School of Biological Sciences, Macquarie University, North Ryde, N.S.W. 2113, Australia
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Shachak M, Chapman EA, Orr Y. Some aspects of the ecology of the desert snail Sphincterochila boissieri in relation to water and energy flow. Isr J Med Sci 1976; 12:887-91. [PMID: 977309] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
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Chapman EA, Graham D. The Effect of Light on the Tricarboxylic Acid Cycle in Green Leaves: II. Intermediary Metabolism and the Location of Control Points. Plant Physiol 1974; 53:886-92. [PMID: 16658810 PMCID: PMC541468 DOI: 10.1104/pp.53.6.886] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
Long term feeding of acetate-2-(14)C, (14)CO(2), citrate-1,5-(14)C, fumarate-2,3-(14)C, and succinate-2,3-(14)C to mung bean (Phaseolus aureus L. var. Mungo) leaves in the dark gave labeling predominantly in tricarboxylic acid cycle intermediates. Kinetics of the intermediates during dark/light/dark transitions showed a light-induced interchange of (14)C between malate and aspartate, usually resulting in an accumulation of (14)C in malate and a decrease of it in aspartate. (14)C-Phosphoenolpyruvate also showed a marked decrease during illumination. Changes in other intermediates of the tricarboxylic acid cycle were relatively minor. The kinetic data have been analyzed using the Chance crossover theorem to locate control points during the dark/light/dark transitions. The major apparent control points are located at malate and isocitrate dehydrogenases, and less frequently at citrate synthase and fumarase. These findings are explained in terms of the light-induced changes in adenine nucleotides and nicotinamide adenine dinucleotides.
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Affiliation(s)
- E A Chapman
- Plant Physiology Unit, Commonwealth Scientific and Industrial Research Organization, Division of Food Research, and School of Biological Sciences, Macquarie University, North Ryde 2113, Sydney, Australia
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Chapman EA, Graham D. The effect of light on the tricarboxylic Acid cycle in green leaves: I. Relative rates of the cycle in the dark and the light. Plant Physiol 1974; 53:879-85. [PMID: 16658809 PMCID: PMC541467 DOI: 10.1104/pp.53.6.879] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
Excised green leaves of mung bean (Phaseolus aureus L. var. Mungo) were used to determine the effect of light on the rate of endogenous respiration via the tricarboxylic acid cycle. Illumination with white light at an intensity of 0.043 gram calories cm(-2)min(-1) (approximately 8600 lux) of visible radiation (400-700 nm) gave a rate of apparent photosynthesis, measured as net CO(2) uptake, of 21 mg CO(2) dm(-2)hr(-1) which was about 11-fold greater than the rate of dark respiration. The feeding of (14)CO(2) or (14)C-labeled acids of the tricarboxylic acid cycle in the dark for 2 hours was established as a suitable method for labeling mitochondrial pools of cycle intermediates.At a concentration of 0.1 mm 3-(3,4-dichlorophenyl)-1,1-dimethylurea, apparent photosynthesis was inhibited 82%, and the refixation of (14)CO(2) derived internally from endogenous respiration was largely prevented. In the presence of this inhibitor endogenous respiration, measured as (14)CO(2) evolution, continued in the light at a rate comparable to that in the dark. Consequently, under these conditions light-induced nonphotosynthetic processes have no significant effect on endogenous dark respiration. Inhibitors of the tricarboxylic acid cycle, malonate and fluoroacetate, were used to determine the relative rates of carbon flux through the cycle in the dark and in the light by measuring the rate of accumulation of (14)C in either succinate or citrate. Results were interpreted to indicate that the tricarboxylic acid cycle functions in the light at a rate similar to that in the dark except for a brief initial inhibition on transition from dark to light. Evidence was obtained that succinate dehydrogenase as well as aconitase, was inhibited in the presence of fluoroacetate.
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Affiliation(s)
- E A Chapman
- Commonwealth Scientific and Industrial Research Organization, Division of Food Research, and School of Biological Sciences, Macquarie University, North Ryde 2113, Sydney, Australia
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Chapman EA, Osmond CB. The Effect of Light on the Tricarboxylic Acid Cycle in Green Leaves: III. A Comparison between Some C(3) and C(4) Plants. Plant Physiol 1974; 53:893-8. [PMID: 16658811 PMCID: PMC541469 DOI: 10.1104/pp.53.6.893] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
The chlorophyll-based specific activity of cytochrome oxidase and three exclusively mitochondrial enzymes of the tricarboxylic acid cycle showed little variation between leaves of C(3) and C(4) plants or between mesophyll and bundle sheath cells of Atriplex spongiosa and Sorghum bicolor. However, a large, light-dependent transfer of label from intermediates of the tricarboxylic acid cycle to photosynthetic products was a feature of leaves of C(4) plants. This light-dependent transfer of label was barely detectable in leaves of C(3) plants and in leaves of F(1) and F(3) hybrids of Atriplex rosea (C(4)) and Atriplex patula spp hastata (C(3)). The light-dependent transfer of label to photosynthetic products in leaves of C(4) plants was inhibited by the tricarboxylic acid cycle inhibitors malonate and fluoroacetate. The requirement for continued tricarboxylic acid cycle activity was also indicated in experiments with specifically labeled succinate-(14)C. These experiments, together with the distribution of (14)C in glucose prepared from sucrose-(14)C formed during the metabolism of succinate-2,3-(14)C, confirmed that the photosynthetic metabolism of malate and aspartate derived from the tricarboxylic acid cycle, and not the refixation of respiratory CO(2), was the main path of carbon from the cycle to photosynthesis.
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Affiliation(s)
- E A Chapman
- Department of Environmental Biology, Research School of Biological Sciences, Australian National University, Canberra, A. C. T
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