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  • 1
    Electronic Resource
    Electronic Resource
    Disruption of Ca2+ Homeostasis In Trypanosoma Cruzi By Crystal Violet (1993)
    Oxford, UK : Blackwell Publishing Ltd
    The @journal of eukaryotic microbiology 40 (1993), S. 0 
    Details
    ISSN: 1550-7408
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: . We have demonstrated previously that crystal violet induces a rapid, dose-related collapse of the inner mitochondrial membrane potential of Trypanosoma cruzi epimastigotes. In this work, we show that crystal violet-induced dissipation of the membrane potential was accompanied by an efflux of Ca2+ from the mitochondria. In addition, crystal violet inhibited the ATP-dependent, oligomycin-, and antimycin A-insensitive Ca2+ uptake by digitonin-permeabilired epimastigotes. Crystal violet also induced Ca2+ release from the mitochondria and endoplasmic reticulum of digitonin-permeabilized trypomastigotes. Furthermore, crystal violet inhibited Ca2+ uptake and the (Ca2+-Mg2+)ATPase of a highly enriched plasma membrane fraction of epimastigotes, thus indicating an inhibition of other calcium transport mechanisms of the cells. Disruption of Ca2+ homeostasis by crystal violet may be a key process leading to trypanosome cell injury by this drug.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1550-7408.1993.tb04921.x
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  • 2
    Electronic Resource
    Electronic Resource
    P-type Proton ATPases are Involved in Intracellular Calcium and Proton Uptake in the Plant Parasite Phytomonas francai (2005)
    Oxford, UK : Blackwell Publishing
    The @journal of eukaryotic microbiology 52 (2005), S. 0 
    Details
    ISSN: 1550-7408
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Abstract. The use of digitonin to permeabilize the plasma membrane of promastigotes of Phytomonas francai allowed the identification of two non-mitochondrial Ca2+ compartments; one sensitive to ionomycin and vanadate (neutral or alkaline), possibly the endoplasmic reticulum, and another sensitive to the combination of nigericin plus ionomycin (acidic), possibly the acidocalcisomes. A P-type (phospho-intermediate form) Ca2+-ATPase activity was found to be responsible for intracellular Ca2+ transport in these cells, with no evidence of a mitochondrial Ca2+ transport activity. ATP-driven acidification of internal compartments in cell lysates and cells mechanically permeabilized was assayed spectrophotometrically with acridine orange. This activity was inhibited by low concentrations of vanadate and digitonin, was insensitive to bafilomycin A1, and stimulated by Na+ ions. Taken together, our results indicate that P-type ATPases are involved in intracellular Ca2+ and H+ transport in promastigotes of P. francai.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1550-7408.2005.3309rr.x
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  • 3
    Electronic Resource
    Electronic Resource
    The Sterol Composition of Trypanosoma cruzi Changes After Growth in Different Culture Media and Results in Different Sensitivity to Digitonin-Permeabilization (2001)
    Oxford, UK : Blackwell Publishing Ltd
    The @journal of eukaryotic microbiology 48 (2001), S. 0 
    Details
    ISSN: 1550-7408
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: . Respiration, oxidative phosphorylation, and the corresponding changes in membrane potential (ΔΨ) of Trypanosoma cruzi epimastigotes grown either in liver infusion-tryptose (LIT) or brain heart infusion (BHI) culture medium were assayed in situ using digitonin to render their plasma membrane permeable to succinate, ADP, safranine O, and other small molecules. When the cells were permeabilized with 64 μM digitonin, a concentration previously used with epimastigotes, the ability of the cells grown in LIT medium to sustain oxidative phosphorylation was demonstrated by the detection of an oligomycin-sensitive decrease in mitochondrial membrane potential induced by ADP. In contrast, the cells grown in BHI medium were not able to sustain a stable membrane potential and did not respond to ADP addition. Analyses of oxygen consumption by these permeabilized cells indicated that the rate of basal respiration, which was similar in both cell types, was significantly decreased by 64 μM digitonin. Addition of ADP to the permeabilized cells grown in LIT medium promoted an oligomycin-sensitive transition from resting to phosphorylating respiration in contrast to the cells grown in BHI medium, whose respiration decreased steadily and did not respond either to ADP or CCCP. Titration of the cells grown in BHI medium with different digitonin concentrations indicated that their mitochondria have higher sensitivity to digitonin than those grown in LIT medium. Analysis of the sterol composition of epimastigotes grown in the two different media showed a higher percentage of cholesterol in total and mitochondrial extracts of epimastigotes grown in BHI medium as compared to those grown in LIT medium, suggesting the involvement of this sterol in their increased sensitivity to digitonin-permeabilization.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1550-7408.2001.tb00195.x
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  • 4
    Electronic Resource
    Electronic Resource
    PUMPing plants (1995)
    [s.l.] : Nature Publishing Group
    Nature 375 (1995), S. 24-24 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] SIR - Flowering and fruit ripening are triggered by a burst of respiration and heat production possibly related to a mitocnondrial, cyanide-resistant, uncoupled electron transport pathway1. In mammals, transient thermogenesis is linked to a mitochondrial uncoupling ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/375024a0
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  • 5
    Electronic Resource
    Electronic Resource
    Role of Fe(III) in Fe(II)citrate-mediated peroxidation of mitochondrial membrane lipids (1999)
    Springer
    Molecular and cellular biochemistry 196 (1999), S. 163-168 
    Details
    ISSN: 1573-4919
    Keywords: Fe(II)citrate ; free radicals ; iron ; lipid peroxidation ; mitochondria ; reactive oxygen species
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract In this report we study the effect of Fe(III) on lipid peroxidation induced by Fe(II)citrate in mitochondrial membranes, as assessed by the production of thiobarbituric acid-reactive substances and antimycin A-insensitive oxygen uptake. The presence of Fe(III) stimulates initiation of lipid peroxidation when low citrate:Fe(II) ratios are used (≤ 4:1). For a citrate:total iron ratio of 1:1 the maximal stimulation of lipid peroxidation by Fe(III) was observed when the Fe(II):Fe(III) ratio was in the range of 1:1 to 1:2. The lag phase that accompanies oxygen uptake was greatly diminished by increasing concentrations of Fe(III) when the citrate:total iron ratio was 1:1, but not when this ratio was higher. It is concluded that the increase of lipid peroxidation by Fe(III) is observed only when low citrate:Fe(II) ratios were used. Similar results were obtained using ATP as a ligand of iron. Monitoring the rate of spontaneous Fe(II) oxidation by measuring oxygen uptake in buffered medium, in the absence of mitochondria, Fe(III)-stimulated oxygen consumption was observed only when a low citrate:Fe(II) ratio was used. This result suggests that Fe(III) may facilitate the initiation and/or propagation of lipid peroxidation by increasing the rate of Fe(II)citrate-generated reactive oxygen species.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1006988129221
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  • 6
    Electronic Resource
    Electronic Resource
    Characteristics of Fe(II)ATP complex-induced damage to the rat liver mitochondrial membrane (1995)
    Springer
    Molecular and cellular biochemistry 145 (1995), S. 53-60 
    Details
    ISSN: 1573-4919
    Keywords: mitochondria ; oxidative stress ; iron ; lipid peroxidation ; membrane permeability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract It is well established that several iron complexes can induce oxidative damage in hepatic mitochondrial membranes by catalyzing the formation of ·OH radicals and/or by promoting lipid peroxidation. This is a relevant process for the molecular basis of iron overload diseases. The present work demonstrates that Fe(II)ATP complexes (5–50μM) promote an oxygen consumption burst in a suspension of isolated rat liver mitochondria (either in the absence or presence of Antimycin A), caused mainly by lipid peroxidation. Fe(II)ATP alone induced small levels of oxygen uptake but no burst. The time course of Fe(II)ATP oxidation to Fe(III)ATP in the extramitochondrial media also reveals a simultaneous ‘burst phase’. The iron chelator Desferal (DFO) or the chain-break antioxidant butylated hydroxytoluene (BHT) fully prevented both lipid peroxidation (quantified as oxygen uptake burst) and mitochondrial swelling. DFO and BHT were capable of stopping the ongoing process of peroxidation at any point of their addition to the mitochondrial suspension. Conversely, DFO and BHT only halted the Fe(II)ATP-induced mitochondrial swelling at the onset of the process. Fe(II)ATP could also cause the collapse of mitochondrial potential, which was protected by BHT if added at the onset of the damaging process. These results, as well as correlation studies between peroxidation and mitochondrial swelling, suggest that a two phase process is occurring during Fe(II)ATP-induced mitochondrial damage: one dependent and another independent of lipid peroxidation. The involvement of lipid peroxidation in the overall process of mitochondrial membrane injury is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00925713
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  • 7
    Electronic Resource
    Electronic Resource
    Oxidative damage to sarcoplasmic reticulum Ca2+-pump induced by Fe2+/H2O2/ascorbate is not mediated by lipid peroxidation or thiol oxidation and leads to protein fragmentation (1996)
    Springer
    Molecular and cellular biochemistry 159 (1996), S. 105-114 
    Details
    ISSN: 1573-4919
    Keywords: sarcoplasmic reticulum ; Ca2+-ATPase ; free radicals ; protein oxidation ; lipid peroxidation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract The major protein in the sarcoplasmic reticulum (SR) membrane is the Ca2+ transporting ATPase which carries out active Ca2+ pumping at the expense of ATP hydrolysis. The aim of this work was to elucidate the mechanisms by which oxidative stress induced by Fenton's reaction (Fe2+ + H2O2 → HO· + OH−+ Fe3+) alters the function of SR. ATP hydrolysis by both SR vesicles (SRV) and purified ATPase was inhibited in a dose-dependent manner in the presence of 0–1.5 MM H2O2 plus 50 μM Fe2+ and 6 mM ascorbate. Ca2+ uptake carried out by the Ca2+-ATPase in SRV was also inhibited in parallel. The inhibition of hydrolysis and Ca2+ uptake was not prevented by butylhydroxytoluene (BHT) at concentrations which significantly blocked formation of thiobarbituric acid-reactive substances (TBARS), suggesting that inhibition of the ATPase was not due to lipid peroxidation of the SR membrane. In addition, dithiothreitol (DTT) did not prevent inhibition of either ATPase activity or Ca2+ uptake, suggesting that inhibition was not related to oxidation of ATPase thiols. The passive efflux of 45Ca2+ from pre-loaded SR vesicles was greatly increased by oxidative stress and this effect could be only partially prevented (ca 20%) by addition of BHT or DTT. Trifluoperazine (which specifically binds to the Ca2+-ATPase, causing conformational changes in the enzyme) fully protected the ATPase activity against oxidative damage. These results suggest that the alterations in function observed upon oxidation of SRV are mainly due to direct effects on the Ca2+-ATPase. Electrophoretic analysis of oxidized Ca2+-ATPase revealed a decrease in intensity of the silver-stained 110 kDa Ca2+-ATPase band and the appearance of low molecular weight peptides (MW 〈 100 kDa) and high molecular weight protein aggregates. Presence of DTT during oxidation prevented the appearance of protein aggregates and caused a simultaneous increase in the amount of low molecular weight peptides. We propose that impairment of function of the Ca2+-pump may be related to aminoacid oxidation and fragmentation of the protein.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00420912
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  • 8
    Electronic Resource
    Electronic Resource
    The Role of Reactive Oxygen Species in Mitochondrial Permeability Transition (1997)
    Springer
    Bioscience reports 17 (1997), S. 43-52 
    Details
    ISSN: 1573-4935
    Keywords: Calcium ; cyclosporin A ; lipid peroxidation ; mitochondria ; mitochondrial membrane permeability transition ; protein oxidation ; reactive oxygen species
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract We have provided evidence that mitochondrial membrane permeability transition induced by inorganic phosphate, uncouplers or prooxidants such as t-butyl hydroperoxide and diamide is caused by a Ca2+-stimulated production of reactive oxygen species (ROS) by the respiratory chain, at the level of the coenzyme Q. The ROS attack to membrane protein thiols produces cross-linkage reactions, that may open membrane pores upon Ca2+ binding. Studies with submitochondrial particles have demonstrated that the binding of Ca2+ to these particles (possibly to cardiolipin) induces lipid lateral phase separation detected by electron paramagnetic resonance experiments exploying stearic acids spin labels. This condition leads to a disorganization of respiratory chain components, favoring ROS production and consequent protein and lipid oxidation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1027335217774
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  • 9
    Electronic Resource
    Electronic Resource
    Inhibition of Mitochondrial Permeability Transition by Low pH is Associated with Less Extensive Membrane Protein Thiol Oxidation (1999)
    Springer
    Bioscience reports 19 (1999), S. 525-533 
    Details
    ISSN: 1573-4935
    Keywords: Mitochondrial permeability transition ; acid pH ; protein sulfhydryl oxidation ; calcium ; reactive oxygen species
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Ca2+ and inorganic phosphate-induced mitochondrial swelling and membrane protein thiol oxidation, which are associated with mitochondrial permeability transition, are inhibited by progressively decreasing the incubation medium pH between 7.2 and 6.0. Nevertheless, the detection of mitochondrial H2O2 production under these conditions is increased. Permeability transition induced by phenylarsine oxide, which promotes membrane protein thiol cross-linkage in a process independent of Ca2+ or reactive oxygen species, is also strongly inhibited in acidic incubation media. In addition, we observed that the decreased protein thiol reactivity with phenylarsine oxide or phenylarsine oxide-induced swelling at pH 6.0 is reversed by diethyl pyrocarbonate, in a hydroxylamine-sensitive manner. These results provide evidence that the inhibition of mitrochondrial permeability transition observed at lower incubation medium pH is mediated by a decrease in membrane protein thiol reactivity, related to the protonation of protein histidyl residues.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1020210827389
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  • 10
    Electronic Resource
    Electronic Resource
    Permeability Transition Pore Closure Promoted by Quinine (1999)
    Springer
    Journal of bioenergetics and biomembranes 31 (1999), S. 153-157 
    Details
    ISSN: 1573-6881
    Keywords: rat liver mitochondria ; membrane permeability transition ; calcium ion ; quinine
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Physics
    Notes: Abstract The mitochondrial membrane permeability transition induced byCa2+ is inhibited by quinine in a dose-dependent fashion.Competition experiments strongly suggest that quinine displacesCa2+ bound to the inner membrane. This is supported byexperiments showing that quinine inhibits Ca2+-dependent butnot Ca2+-independent mitochondrial swelling induced byphenylarsine oxide. As with Ca2+ chelators, quinine inducespermeability transition pore closure preventing the contraction induced bypoly(ethylene glycol) 2000 in mitochondria preswollen by incubation in KSCNmedium containing Ca2+ and inorganic phosphate. These resultssuggest that quinine dislodges Ca2+ bound to the protein site,which triggers pore opening.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1005455912711
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