scholarly journals The O2-dependence of respiration and H2O2 production in the parasitic nematode Ascaridia galli

1988 ◽  
Vol 256 (2) ◽  
pp. 633-639 ◽  
Author(s):  
T A Paget ◽  
M Fry ◽  
D Lloyd
Keyword(s):  
Electron Transport ◽  
Muscle Tissue ◽  
Parasitic Nematode ◽  
H2o2 Production ◽  
Reproductive Tissue ◽  
Ascaridia Galli ◽  
Transport Pathway ◽  
Transport Pathways ◽  
Transport Chain ◽  
Carbonyl Cyanide

1. Respiration in the parasitic nematode worm Ascaridia galli was inhibited at O2 concentrations in excess of 255 microM, and an apparent Km,O2 of 174 microM was determined. 2. Mitochondria-enriched fractions isolated from the tissues of A. galli have much lower apparent Km,O2 values (approx. 5 microM). They produce H2O2 in the energized state; higher rates of H2O2 production were observed in the presence of the uncoupler carbonyl cyanide m-chlorophenylhydrazone. 3. Antimycin A inhibited respiration in muscle tissue mitochondria by 10%, but had no effect on respiration in gut + reproductive tissue mitochondria; the major portion of respiration in both types of mitochondria could be attributed to an alternative electron-transport pathway. 4. o-Hydroxydiphenyl, an inhibitor of alternative electron-transport pathways, inhibits respiration by 98% and completely inhibits the production of H2O2 in gut-plus-reproductive-tissue mitochondria; respiration and H2O2 production in muscle tissue mitochondria were inhibited by 90 and 86% respectively. 5. Another inhibitor of alternative electron transport, salicylhydroxamic acid, had the same effect as o-hydroxydiphenyl on H2O2 production and respiration in gut-plus-reproductive-tissue mitochondria. However, its effect on muscle tissue mitochondria was complex; a low concentration (0.35 mM) stimulated H2O2 production, whereas 3 mM inhibited respiration by 87% and prevented H2O2 production completely. 6. The similarities between the apparent Km,O2 values for H2O2 production and respiration in muscle mitochondria and in gut-plus-reproductive-tissue mitochondria suggests that the site of H2O2 production on the alternative electron-transport chain is cytochrome ‘o’. 7. These results are discussed in relation to potential O2 toxicity in A. galli.

scholarly journals Hydrogen peroxide production in uncoupled mitochondria of the parasitic nematode worm Nippostrongylus brasiliensis

1987 ◽  
Vol 243 (2) ◽  
pp. 589-595 ◽  
Author(s):  
T A Paget ◽  
M Fry ◽  
D Lloyd
Keyword(s):  
Electron Transport ◽  
Parasitic Nematode ◽  
H2o2 Production ◽  
Nippostrongylus Brasiliensis ◽  
Antimycin A ◽  
Transport Pathway ◽  
Salicylhydroxamic Acid ◽  
Low Concentrations ◽  
Carbonyl Cyanide ◽  
Nematode Worm

1. Mitochondria from the parasitic nematode worm Nippostrongylus brasiliensis produce H2O2 in the energized state; higher rates of H2O2 production were observed in the presence of the uncoupler carbonyl cyanide m-chlorophenylhydrazone. 2. Antimycin A inhibits respiration and H2O2 production by 70 and 65% respectively; the residual activities can be attributed to alternative electron-transport pathway(s). 3. o-Hydroxydiphenyl and 1,3,5-trihydroxybenzene, inhibitors of alternative electron transport, inhibit respiration by 37% and H2O2 production by 26%. 4. Another inhibitor of alternative electron transport, salicylhydroxamic acid, shows a complex mode of action; low concentrations (less than 0.5 mM) stimulate respiration and H2O2 production, whereas 2 mM-salicylhydroxamic acid inhibited respiration by 35% and stopped H2O2 production completely. 5. O2 thresholds were observed for the inhibition of respiration at O2 concentrations greater than 57.7 microM and inhibition of H2O2 production (greater than 20.5 microM-O2); apparent Km values for oxygen were 5.5 microM and 3.0 microM respectively. 6. In the presence of antimycin A the O2-inhibition thresholds and apparent Km values for O2 of respiration and H2O2 production matched closely, suggesting that the alternative oxidase is a likely site of H2O2 production. 7. These results are discussed in relation to O2 toxicity to N. brasiliensis.

scholarly journals Impact of High Light on Reactive Oxygen Species Production within Photosynthetic Biological Membranes

2015 ◽  
Vol 6 (2) ◽  
pp. 50 ◽  
Author(s):  
Vetoshkina D. V. ◽  
Borisova-Mubarakshina M. M. ◽  
Naydov I. A. ◽  
Kozuleva M. A. ◽  
Ivanov B. N.
Keyword(s):  
Reactive Oxygen Species ◽  
Electron Transport ◽  
Electron Transport Chain ◽  
Reactive Oxygen ◽  
Photosynthetic Electron Transport ◽  
Lipid Phase ◽  
H2o2 Production ◽  
Oxygen Species ◽  
Photosynthetic Electron Transport Chain ◽  
Transport Chain

In this study we describe the mechanisms of reactive oxygen species (ROS) production in the photosynthetic electron transport chain of higher plants chloroplasts under illumination. We implement an improved method for the measurement of hydrogen peroxide (H2O2) production in lipid phase of photosynthetic membranes of chloroplasts. Total rate of H2O2 production and the production within the thylakoid membrane under operation of photosynthetic electron transport chain is evaluated. Obtained data show that even in the presence of an efficient electron acceptor, methyl viologen, an increase in light intensity leads to an increase in H2O2 production mainly within the thylakoid membranes. The role of H2O2 produced within the photosynthetic biological membrane is discussed.

Formation mechanisms of superoxide radical and hydrogen peroxide in chloroplasts, and factors determining the signalling by hydrogen peroxide

2018 ◽  
Vol 45 (2) ◽  
pp. 102 ◽  
Author(s):  
Boris N. Ivanov ◽  
Maria M. Borisova-Mubarakshina ◽  
Marina A. Kozuleva
Keyword(s):  
Hydrogen Peroxide ◽  
Electron Transport ◽  
Thylakoid Membrane ◽  
Electron Transport Chain ◽  
Superoxide Radical ◽  
Photosynthetic Electron Transport ◽  
Formation Mechanisms ◽  
H2o2 Production ◽  
Photosynthetic Electron Transport Chain ◽  
Transport Chain

Reduction of O2 molecule to superoxide radical, O2•−, in the photosynthetic electron transport chain is the first step of hydrogen peroxide, H2O2, production in chloroplasts in the light. The mechanisms of O2 reduction by ferredoxin, by the components of the plastoquinone pool, and by the electron transfer cofactors in PSI are analysed. The data indicating that O2•− and H2O2 can be produced both outside and within thylakoid membrane are presented. The H2O2 production in the chloroplast stroma is described as a result of either dismutation of O2•− or its reduction by stromal reductants. Formation of H2O2 within thylakoid membrane in the reaction of O2•− with plastohydroquinone is examined. The significance of both ways of H2O2 formation for specificity of the signal being sent by photosynthetic electron transport chain to cell adaptation systems is discussed.

scholarly journals Haemoprotein terminal oxidases in the nematodes Nippostrongylus brasiliensis and Ascaridia galli

1988 ◽  
Vol 256 (1) ◽  
pp. 295-298 ◽  
Author(s):  
T A Paget ◽  
M Fry ◽  
D Lloyd
Keyword(s):  
Muscle Tissue ◽  
Endogenous Respiration ◽  
Nippostrongylus Brasiliensis ◽  
Reproductive Tissue ◽  
Ascaridia Galli ◽  
Difference Spectra ◽  
Cytochrome Aa3 ◽  
Action Spectra ◽  
Terminal Oxidases ◽  
Photochemical Action

1. Mitochondria isolated from the gut-dwelling nematodes Nippostrongylus brasiliensis and Ascaridia galli (muscle and gut + reproductive tissue) were examined for cytochromes, and it was observed that N. brasiliensis and A. galli muscle tissue mitochondria contained a-, b- and c-type cytochromes, but their stoichiometries were quite different (1:2:1.9 and 1:11.4:13.6 respectively); A. galli gut + reproductive-tissue mitochondria, however, only contained b and c cytochromes, in a ratio of 1:0.8. 2. CO difference spectra showed the presence of CO-reacting b-type cytochrome(s) in all three types of mitochondria; the fast-reacting species comprised 30, 44 and 39% of the total in N. brasiliensis, A. galli muscle and A. galli gut + reproductive-tissue mitochondria respectively. 3. Cytochrome aa3 was observed in N. brasiliensis mitochondria and in those from A. galli muscle, but was below the level of detectability (less than 0.005 nmol/mg of protein) for A. galli gut + reproductive-tissue mitochondria. 4. Photochemical action spectra for the reversal of CO inhibition of the endogenous respiration of whole worms (at 24 microM- and 40 microM-O2 respectively for N. brasiliensis and A. galli) gave maxima at 598 and 542-543 nm, corresponding to the alpha- and beta-absorption maxima of cytochrome aa3, and at 567 nm (b-type cytochrome) for both worms. These results suggest that cytochrome aa3 is the major functional oxidase in N. brasiliensis, whereas the CO-reacting b-type cytochrome dominates in A. galli.

scholarly journals Function of the Cytochrome bc1-aa3 Branch of the Respiratory Network in Mycobacteria and Network Adaptation Occurring in Response to Its Disruption

2005 ◽  
Vol 187 (18) ◽  
pp. 6300-6308 ◽  
Author(s):  
Limenako G. Matsoso ◽  
Bavesh D. Kana ◽  
Paul K. Crellin ◽  
David J. Lea-Smith ◽  
Assunta Pelosi ◽  
...  
Keyword(s):  
Electron Transport ◽  
Respiratory Pathway ◽  
Transport Pathway ◽  
Network Adaptation ◽  
Transport Chain ◽  
Respiratory Network ◽  
Oxygen Starvation ◽  
And Function ◽  
Mycobacterial Growth ◽  
Partial Genome

ABSTRACT The aerobic electron transport chain in Mycobacterium smegmatis can terminate in one of three possible terminal oxidase complexes. The structure and function of the electron transport pathway leading from the menaquinol-menaquinone pool to the cytochrome bc 1 complex and terminating in the aa 3-type cytochrome c oxidase was characterized. M. smegmatis strains with mutations in the bc 1 complex and in subunit II of cyctochome c oxidase were found to be profoundly growth impaired, confirming the importance of this respiratory pathway for mycobacterial growth under aerobic conditions. Disruption of this pathway resulted in an adaptation of the respiratory network that is characterized by a marked up-regulation of cydAB, which encodes the bioenergetically less efficient and microaerobically induced cytochrome bd-type menaquinol oxidase that is required for the growth of M. smegmatis under O2-limiting conditions. Further insights into the adaptation of this organism to rerouting of the electron flux through the branch terminating in the bd-type oxidase were revealed by expression profiling of the bc 1-deficient mutant strain using a partial-genome microarray of M. smegmatis that is enriched in essential genes. Although the expression profile was indicative of an increase in the reduced state of the respiratory chain, blockage of the bc 1-aa 3 pathway did not induce the sentinel genes of M. smegmatis that are induced by oxygen starvation and are regulated by the DosR two-component regulator.

Cytochemical localization of cytochrome oxidase in tissues of parasitic nematodes

Parasitology ◽  
1985 ◽  
Vol 90 (1) ◽  
pp. 145-156 ◽  
Author(s):  
M. Fry ◽  
J. E. Beesley
Keyword(s):  
Cytochrome Oxidase ◽  
Oxidase Activity ◽  
Parasitic Nematodes ◽  
Nippostrongylus Brasiliensis ◽  
Reproductive Tissue ◽  
Ascaridia Galli ◽  
Transport Pathway ◽  
Cytochemical Staining ◽  
Cytochemical Localization ◽  
Cytochrome Oxidase Activity

Cytochemical staining with diaminobenzidine (DAB) has been used to locate cytochrome oxidase activity in mitochondria from major tissues of three intestinal parasitic nematodes, Nippostrongylus brasiliensis, Haemonchus contortus and Ascaridia galli. Deposition of DAB reaction product was uniform and relatively intense in mitochondria from all tissues studied in N. brasiliensis. However, mitochondria from different tissues of H. contortus and A. galli varied considerably in their cytochemical staining, decreasing in the order hypodermis < muscle < gut < reproductive tissue. Mitochondria in gut and reproductive tissue of A. galli possessed little or no cytochrome oxidase activity. These results are compatible with respect to oxygen availability and the extent and localization of the mammalian-type aerobic mitochondrial electron transport pathway in intestinal parasitic nematodes.

Continuous electron transport pathways constructed in TiO2 sub-microsphere films for high-performance dye-sensitized solar cells

RSC Advances ◽  
2015 ◽  
Vol 5 (23) ◽  
pp. 17493-17500 ◽  
Author(s):  
Yong Ding ◽  
Yanmei Ma ◽  
Li Tao ◽  
Linhua Hu ◽  
Guang Li ◽  
...  
Keyword(s):  
Solar Cells ◽  
Electron Transport ◽  
High Performance ◽  
Dye Sensitized Solar Cells ◽  
Transport Pathway ◽  
Transport Pathways ◽  
Dye Sensitized ◽  
Sensitized Solar Cells ◽  
Electron Transport Pathway

Different concentrations of TiO2 nanocrystallines are introduced into the sub-microspheres of photoanodes to construct a continuous electron transport pathway for high-performance DSSCs.

scholarly journals Control of Intramolecular Electron Transport Pathways by Varying Localized Electron Distribution

2021 ◽  
Author(s):  
Dahai Zhou ◽  
Ping Duan ◽  
Yu Zhou ◽  
Chuan Li ◽  
Yaping Wang ◽  
...  
Keyword(s):  
Electron Transport ◽  
Single Molecule ◽  
Quantum Interference ◽  
Flicker Noise ◽  
Transport Pathway ◽  
Transport Pathways ◽  
Highest Occupied Molecular Orbital ◽  
Before And After ◽  
New Strategy ◽  
Theoretical Simulations

Abstract The control of different electron transport pathways by quantum interference (QI) effects offers a unique opportunity for the modulation of electrical properties in molecular electronic devices and materials. In this work, we propose a chemical way to control the intramolecular electron transport pathways by the localization of the highest occupied molecular orbital (HOMO) distribution. The negative charge injection in para-carbazole by deprotonation exhibited a fourfold suppression of single-molecule conductance, while the conductance is almost the same for meta-carbazole before and after deprotonation. The flicker noise analyses and theoretical simulations revealed the localized distribution of HOMO on the para-carbazole center, leading to the appearance of destructive quantum interference (DQI) effect for the control of electron transport pathway. This strategy of reaction-induced orbital localization offers a new strategy for the control of charge transport through molecular devices and materials.

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