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Eduardo Zeiger - One of the best experts on this subject based on the ideXlab platform.
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Temperature dependence of guard Cell Respiration and stomatal conductance co-segregate in an F2 population of Pima cotton
Functional Plant Biology, 2000Co-Authors: Miguel A. Quinones, Eduardo ZeigerAbstract:In Pima cotton (Gossypium barbadense L.), stomatal conductance shows a strong response to temperature. At high temperature (40˚C), the stomatal conductance of greenhouse- and growth chamber-grown leaves is three and four times higher than that measured at lower temperature (25oC), respectively. The segregation of stom-atal conductance observed in an F2 population obtained from a cross between a primitive cotton (B368) and a modern Pima line (Pima S-6) increased substantially with temperature in both light and darkness. Furthermore, F2 segregants with high stomatal conductance at high temperature were more sensitive to temperature, showing larger changes in conductance in response to an increase in temperature when compared to F2 segregants having low stomatal conductance. Rates of guard Cell Respiration measured in enzymatically-cleaned epidermal peels, mechanically isolated from the same F2 plants, showed the same temperature dependence. The temperature-induced Respiration enhancement was higher in guard Cells with high Respiration rates. There were positive correlations between stomatal conductance and guard Cell Respiration rates, and between stomatal conductance and the sensitivity of Respiration to changes in temperature. These results imply that guard Cell Respiration and stomatal conductance co-segregate in Pima cotton plants, suggesting that guard Cell Respiration is a component of the sensory transduction pathway controlling stomatal responses to temperature.
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The temperature sensitivity of guard Cell Respiration CO- segregates with stomatal conductances in a F2 population of pima cotton
1993Co-Authors: Quinones, Eduardo ZeigerAbstract:Stomatal conductances in lines of Pima cotton selected for higher yields and heat resistance increase as a function of selection. Lines with contrasting rates of stomatal conductances also have contrasting rates of guard Cell Respiration and proton pumping. In this work, we studied stomatal conductances and guard Cell Respiration rates in a F2 population of a cross between S-6, a heat-resistant, high yielding line, and B368, a heat sensitive primitive cotton. F2 plants were grown in a greenhouse (temperature=30[degrees]C at noon) and a growth chamber (12 h light, 40[degrees]C/12 h dark 28[degrees]C). conductances were 3-fold higher at 40[degrees]C than at 25[degrees]C in greenhouse-grown plants and 4-fold higher in growth chamber-grown plants. The range of stomatal conductances in segregating F2 plants increased sharply with temperature, indicating that the genetic differences between the parental populations are better expressed at high temperature. Respiration rates of guard Cells measured in mechanically isolated, enzymatically cleaned epidermis, co-segregated with stomatal conductances. Plants with high stomatal conductances had high rates of guard Cell Respiration. The slope of guard Cell Respiration as a function of temperature increased linearly with stomatal conductances. The co-segregation of rates of guard Cell Respiration and stomatal conductances indicates that both properties are undermore » genetic control, and that guard Cell Respiration is a component of the sensory transduction of the stomatal response to temperature.« less
I V Ogneva - One of the best experts on this subject based on the ideXlab platform.
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Drosophila melanogaster Sperm under Simulated Microgravity and a Hypomagnetic Field: Motility and Cell Respiration.
International journal of molecular sciences, 2020Co-Authors: I V Ogneva, Nikolay S. Biryukov, Maria A. Usik, Maria V. Burtseva, Yuliya S. Zhdankina, Vladimir Sychev, Oleg OrlovAbstract:The role of the Earth’s gravitational and magnetic fields in the evolution and maintenance of normal processes of various animal species remains unclear. The aim of this work was to determine the effect of simulated microgravity and hypomagnetic conditions for 1, 3, and 6 h on the sperm motility of the fruit fly Drosophila melanogaster. In addition to the usual diet, the groups were administered oral essential phospholipids at a dosage of 500 mg/kg in medium. The speed of the sperm tails was determined by video recording and analysis of the obtained video files, protein content by western blotting, and Cell Respiration by polarography. The results indicated an increase in the speed of movement of the sperm tails after 6 h in simulated microgravity. The levels of proteins that form the axoneme of the sperm tail did not change, but Cellular Respiration was altered. A similar effect occurred with the administration of essential phospholipids. These results may be due to a change in the level of phosphorylation of motor proteins. Exposure to hypomagnetic conditions led to a decrease in motility after 6 h against a background of a decrease in the rate of Cellular Respiration due to complex I of the respiratory chain. This effect was not observed in the flies that received essential phospholipids. However, after 1 h under hypomagnetic conditions, the rate of Cellular Respiration also increased due to complex I, including that in the sperm of flies receiving essential phospholipids.
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Cell Respiration of Rat Cardiomyocytes and Soleus Muscle Fibers under Ultra-Short-Term Antiorthostatic Suspension
International Journal of Biomedicine, 2014Co-Authors: I V Ogneva, O M Veselova, Nikolay S. Biryukov, I M LarinaAbstract:The aim of the study was to analyses rat soleus fibers and left ventricle (LV) cardiomyocyte Cell Respiration after 6, 12, 18, 24 and 72 hours of antiorthostatic suspension by the tail. We measured V0 – basal oxygen consumption rate, V Glu+Mal – Respiration velocity over a catalyst of malate and glutamate (5 mM glutamate + 2 mM malate) and Vmax – maximal respiratory rate (in the presence of 1 mM ADP) using the Saks polarography technique. We also determined the cytochrome c content and expression of its gene (Cycs) and the GAPDH gene using Western blotting and real-time PCR. Cell Respiration parameters in cardiomyocytes increased after 18 hours of suspension: V0 increased by 35%, VGlu+Mal by 90% and Vmax by 85% in comparison with the control group (p
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Parameters of Fiber Cell Respiration and Desmin Content in Rat Soleus Muscle at Early Stages of Gravitational Unloading
Biophysics, 2012Co-Authors: T M Mirzoev, O M Veselova, I M Larina, B S Shenkman, Nikolay S. Biryukov, I V OgnevaAbstract:The aim of the work was to study the parameters of fiber Cell Respiration and desmin content in Wistar rat soleus muscle after 1, 3, 7 and 14 days of gravitational unloading. Gravitational unloading was simulated by antiorthostatic hindlimb suspension. The parameters of Cell Respiration were determined using polarography, and desmin content was assessed by means of Western blotting. The results showed that the intensity of Cell Respiration is reduced after three days of gravitational unloading, reaches a minimum level after seven days and slightly increases by the fourteenth day of hindlimb unloading, as well as the content of desmin, which, however, to the fourteenth day returns to the control level. Taking into account that mitochondrial function depends on the state of cytoskeleton, the data allow us to assume that early reduction of the intensity of Cell Respiration under unloading could be caused by degradation of the protein desmin that determines the intraCellular localization of mitochondria.
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Parameters of fibers Cell Respiration and desmin content in rat soleus muscle at early stages of gravitational unloading
Biofizika, 2012Co-Authors: T M Mirzoev, N S Biriukov, O M Veselova, I M Larina, B S Shenkman, I V OgnevaAbstract:The aim of the work was to study the parameters of fibers Cell Respiration and desmin content in Wistar rat soleus muscle after 1, 3, 7 and 14 days of gravitational unloading. Gravitational unloading was simulated by antiorthostatic hindlimb suspension. The parameters of Cell Respiration were determined using the polarography, and desmin content was assessed by means of Western blotting. The results showed that the intensity of Cell Respiration is reduced after three days of gravitational unloading, reaches a minimum level after seven days and slightly increases by the fourteenth day of hindlimb unloading, as well as the content of desmin, which, however, to the fourteenth day returns to the control level. Taking into account that mitochondrial function depends on the state of cytoskeleton the data allow us to assume that early reduction of the intensity of Cell Respiration under unloading could be caused by degradation of the protein desmin that determines intraCellular localization of mitochondria.
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Effects of Long-Term Microgravitation Exposure on Cell Respiration of the Rat Musculus Soleus Fibers
Bulletin of experimental biology and medicine, 2011Co-Authors: O. M. Veselova, I V Ogneva, I M LarinaAbstract:Cell Respiration of the m. soleus fibers was studied in Wistar rats treated with succinic acid and exposed to microgravitation for 35 days. The results indicated that Respiration rates during utilization of endogenous and exogenous substrates and the maximum Respiration rate decreased in animals subjected to microgravitation without succinate treatment. The Respiration rate during utilization of exogenous substrate did not increase in comparison with that on endogenous substrates. Succinic acid prevented the decrease in Respiration rate on endogenous substrates and the maximum Respiration rate. On the other hand, the Respiration rate on exogenous substrates was reduced in vivarium control rats receiving succinate in comparison with intact control group. That could indicate changed efficiency of complex I of the respiratory chain due to reciprocal regulation of the tricarbonic acid cycle.
Mårten Wikström - One of the best experts on this subject based on the ideXlab platform.
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eLS - Cytochrome c Oxidase
Encyclopedia of Life Sciences, 2010Co-Authors: Mårten WikströmAbstract:Cytochrome c oxidase is the key enzyme of Cell Respiration in all eukaryotes and many prokaryotes. The cytochrome c oxidases belong to the haem–copper superfamily of structurally and functionally related enzymes; though related in structure, some bacterial variants lack amino acid residues that are known to be obligatory for the function of the members of the main family. All haem–copper oxidases have a unique bimetallic active site catalysing reduction of dioxygen (O2) to water and an adjacent second haem group that donates electrons to this site. Here, the mechanism of O2 reduction is reviewed. The membrane-bound enzyme couples this reaction to translocation of protons across the membrane, and thus functions as a primary energy transducer that contributes to the formation of ATP (adenosine triphosphate) in aerobic life. The most recent knowledge of the function of this ‘proton pump’ is discussed. It is concluded that cytochrome c oxidase is an electrostatic energy-transducing machine with high efficiency. Key Concepts: Cytochrome c oxidase is an electrostatically coupled energy transducer. The high affinity for O2 is due to kinetic ligand trapping. O2 reduction in Cell Respiration yields no reactive oxygen species. Keywords: Cell Respiration; haem–copper oxidases; respiratory chain; ATP synthesis; transmembrane protein; proton translocation; energy transduction; electron transfer; oxygen reduction
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Kinetic trapping of oxygen in Cell Respiration
Nature, 1996Co-Authors: Michael I. Verkhovsky, Joel E. Morgan, Anne Puustinen, Mårten WikströmAbstract:Cell Respiration in eukaryotes is catalysed by the mitochondrial enzyme cytochrome c oxidase. In bacteria there are many variants of this enzyme, all of which have a binuclear haem iron–copper centre at which O2 reduction occurs, and a low-spin haem, which serves as the immediate electron donor to this centre1. It is essential that the components of the Cell respiratory system have a high affinity for oxygen because of the low concentrations of dissolved O2 in the tissues; however, the binding of O2 to the respiratory haem–copper oxidases is very weak2,3. This paradox has been attributed to kinetic trapping during fast reactions of O2 bound within the enzyme's binuclear haem iron–copper centre2. Our earlier work3 indicated that electron transfer from the low-spin haem to the oxygen-bound binuclear centre may be necessary for such kinetic oxygen trapping. Here we show that a specific decrease of this haem–haem electron transfer rate in the respiratory haem–copper oxidase from Escherichia coli leads to a corresponding decrease in the enzyme's operational steady-state affinity for O2. This demonstrates directly that fast electron transfer between the haem groups is a key process in achieving the high affinity for oxygen in Cell Respiration.
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oxygen activation and the conservation of energy in Cell Respiration
Nature, 1992Co-Authors: Gerald T. Babcock, Mårten WikströmAbstract:Many of the membrane-associated oxidases that catalyse respiratory reduction of 02 to water simultaneously couple this exergonic reaction to the translocation of protons across the inner mitochondrial membrane, or the Cell membrane in prokaryotes, a process by which metabolic energy is conserved for subsequent synthesis of ATP. The molecular mechanism of 02 reduction and its linkage to H+ translocation are now emerging. The bimetallic haem iron–copper reaction centre in this family of enzymes is the critical structure for catalysis of both these processes.
Werner Waldhäusl - One of the best experts on this subject based on the ideXlab platform.
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Fenofibrate Impairs Rat Mitochondrial Function by Inhibition of Respiratory Complex I
The Journal of pharmacology and experimental therapeutics, 2004Co-Authors: Barbara Brunmair, Andrea Lest, Katrin Staniek, Florian Gras, Nicole Scharf, Michael Roden, Hans Nohl, Werner Waldhäusl, Clemens FürnsinnAbstract:Fibrates are used for the treatment of dyslipidemia and known to affect mitochondrial function in vitro. To better understand the mechanisms underlying their mitochondrial effects, fibrate actions on complex I of the respiratory chain and Cell Respiration were studied in vitro. In homogenates of rat skeletal muscle, fenofibrate, and to a lesser extent clofibrate, reduced the activity of complex I (10, 30, and 100 microM fenofibrate: -41 +/- 7%, -70 +/- 2%, and -78 +/- 4%; 100 microM clofibrate: -27 +/- 7%; p < 0.005 each). Inhibition of complex I by fenofibrate (100 microM) was confirmed by reduced state 3 Respiration of isolated mitochondria consuming glutamate + malate as substrates for complex I (-33 +/- 4%; p < 0.0005), but not of such consuming succinate as substrate for complex II (-8 +/- 4%; NS). In isolated rat muscle, 24-h fenofibrate exposure (25, 50, and 100 microM) decreased CO(2) production from palmitate (-15 +/- 7%, -23 +/- 8%, and -22 +/- 7%; p < 0.05 each) and increased lactate release (+15 +/- 5%, +14 +/- 5%, and + 17 +/- 6%; p < 0.02 each) indicating impaired Cell Respiration. Ciprofibrate and gemfibrocil (but not bezafibrate) impaired Cell Respiration without any inhibition of complex I. Our findings support the notion that individual fibrates induce mitochondrial dysfunction via different molecular mechanisms and show that fenofibrate predominantly acts by inhibition of complex I of the respiratory chain.
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thiazolidinediones like metformin inhibit respiratory complex i a common mechanism contributing to their antidiabetic actions
Diabetes, 2004Co-Authors: Barbara Brunmair, Katrin Staniek, Florian Gras, Nicole Scharf, Michael Roden, Hans Nohl, Aleksandra Althaym, Renate Clara, Erich Gnaiger, Werner WaldhäuslAbstract:Metformin and thiazolidinediones (TZDs) are believed to exert their antidiabetic effects via different mechanisms. As evidence suggests that both impair Cell Respiration in vitro, this study compared their effects on mitochondrial functions. The activity of complex I of the respiratory chain, which is known to be affected by metformin, was measured in tissue homogenates that contained disrupted mitochondria. In homogenates of skeletal muscle, metformin and TZDs reduced the activity of complex I (30 mmol/l metformin, −15 ± 2%; 100 μmol/l rosiglitazone, −54 ± 7; and 100 μmol/l pioglitazone, −12 ± 4; P < 0.05 each). Inhibition of complex I was confirmed by reduced state 3 Respiration of isolated mitochondria consuming glutamate + malate as substrates for complex I (30 mmol/l metformin, −77 ± 1%; 100 μmol/l rosiglitazone, −24 ± 4; and 100 μmol/l pioglitazone, −18 ± 5; P < 0.05 each), whereas Respiration with succinate feeding into complex II was unaffected. In line with inhibition of complex I, 24-h exposure of isolated rat soleus muscle to metformin or TZDs reduced Cell Respiration and increased anaerobic glycolysis (glucose oxidation: 270 μmol/l metformin, −30 ± 9%; 9 μmol/l rosiglitazone, −25 ± 8; and 9 μmol/l pioglitazone, −45 ± 3; lactate release: 270 μmol/l metformin, +84 ± 12; 9 μmol/l rosiglitazone, +38 ± 6; and 9 μmol/l pioglitazone, +64 ± 11; P < 0.05 each). As both metformin and TZDs inhibit complex I activity and Cell Respiration in vitro, similar mitochondrial actions could contribute to their antidiabetic effects.
Miguel A. Quinones - One of the best experts on this subject based on the ideXlab platform.
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Temperature dependence of guard Cell Respiration and stomatal conductance co-segregate in an F2 population of Pima cotton
Functional Plant Biology, 2000Co-Authors: Miguel A. Quinones, Eduardo ZeigerAbstract:In Pima cotton (Gossypium barbadense L.), stomatal conductance shows a strong response to temperature. At high temperature (40˚C), the stomatal conductance of greenhouse- and growth chamber-grown leaves is three and four times higher than that measured at lower temperature (25oC), respectively. The segregation of stom-atal conductance observed in an F2 population obtained from a cross between a primitive cotton (B368) and a modern Pima line (Pima S-6) increased substantially with temperature in both light and darkness. Furthermore, F2 segregants with high stomatal conductance at high temperature were more sensitive to temperature, showing larger changes in conductance in response to an increase in temperature when compared to F2 segregants having low stomatal conductance. Rates of guard Cell Respiration measured in enzymatically-cleaned epidermal peels, mechanically isolated from the same F2 plants, showed the same temperature dependence. The temperature-induced Respiration enhancement was higher in guard Cells with high Respiration rates. There were positive correlations between stomatal conductance and guard Cell Respiration rates, and between stomatal conductance and the sensitivity of Respiration to changes in temperature. These results imply that guard Cell Respiration and stomatal conductance co-segregate in Pima cotton plants, suggesting that guard Cell Respiration is a component of the sensory transduction pathway controlling stomatal responses to temperature.