scholarly journals Respiration of the rumen ciliate Dasytricha ruminantium Schuberg

1982 ◽  
Vol 206 (2) ◽  
pp. 259-266 ◽  
Author(s):  
N Yarlett ◽  
D Lloyd ◽  
A G Williams
Keyword(s):  
Electron Transport ◽  
Endogenous Respiration ◽  
Tritrichomonas Foetus ◽  
Acetyl Phosphate ◽  
O2 Uptake ◽  
Triton X ◽  
Stimulation Of

The endogenous respiration of the rumen ciliate Dasytricha ruminantium maintained under an O2 tension of 2kPa (approximately 0.02 atm) was partially inhibited by KCN (40% inhibition) and NaN3 (58% inhibition). The organisms lack cytochromes, and sensitivity of respiration to KCN, NaN3, chloroquine and quercetin suggest that the operation of flavoprotein-iron-sulphur-mediated electron transport. As in Tritrichomonas foetus, hydrogenosomal respiration can be stimulated by the addition of CoA in the presence of 0.025% Triton X-100; stimulation by ADP was not detected. Stimulation of pyruvate-supported O2 uptake by Pi suggests that acetate is produced via acetyl phosphate.

scholarly journals Studies on the Energy Metabolism of Human Leukocytes

Blood ◽  
1967 ◽  
Vol 30 (2) ◽  
pp. 168-175 ◽  
Author(s):  
JOHN M. FOSTER ◽  
MARY L. TERRY ◽  
Harriet Gunther
Keyword(s):  
Energy Metabolism ◽  
Electron Transport ◽  
Oxidative Phosphorylation ◽  
Respiratory Control ◽  
Endogenous Respiration ◽  
Mitochondrial Oxidative Phosphorylation ◽  
Human Leukocytes ◽  
Endogenous Activity ◽  
Stimulation Of

Abstract 1. Oxidative phosphorylation has been studied in mitochondrial preparations from human leukocytes, using recently developed methods for homogenization, measuring respiration, and assaying for ATP. 2. Appreciable stimulation of both respiration and phosphorylation was limited to 3 substrates: succinate, malate, and α-glycerophosphate. The effects of other substrates were minimal. 3. The stimulating effects of these 3 substrates responded to inhibitors in a manner typical of mitochondrial oxidative phosphorylation. There was also considerable endogenous activity which, however, was insensitive to inhibitors. It is concluded the endogenous respiration and phosphorylation are not associated with electron transport. Subtracting their values from the data, P/O ratios consistent with good phosphorylation with the 3 substrates are obtained. 4. Studies with oligomycin and dinitrophenol suggest the presence of respiratory control. This indicates the mitochondria are intact. It is concluded that in the intact leukocyte the mitochondria are a major source of ATP.

Electron transport pathways for the oxidation of endogenous substrate(s) in Acidithiobacillus ferrooxidans

2006 ◽  
Vol 52 (4) ◽  
pp. 317-327 ◽  
Author(s):  
Yongqiang Chen ◽  
Isamu Suzuki
Keyword(s):  
Electron Transport ◽  
Electron Acceptor ◽  
Acidithiobacillus Ferrooxidans ◽  
Complex I ◽  
Iron Chelators ◽  
Endogenous Respiration ◽  
Sugar Alcohols ◽  
Transport Pathways ◽  
Endogenous Substrate ◽  
Transport Inhibitors

Oxidation of endogenous substrate(s) of Acidithiobacillus ferrooxidans with O2 or Fe3+ as electron acceptor was studied in the presence of uncouplers and electron transport inhibitors. Endogenous substrate was oxidized with a respiratory quotient (CO2 produced/O2 consumed) of 1.0, indicating its carbohydrate nature. The oxidation was inhibited by complex I inhibitors (rotenone, amytal, and piericidin A) only partially, but piericidin A inhibited the oxidation with Fe3+ nearly completely. The oxidation was stimulated by uncouplers, and the stimulated activity was more sensitive to inhibition by complex I inhibitors. HQNO (2-heptyl-4-hydroxyquinoline N-oxide) also stimulated the oxidation, and the stimulated respiration was more sensitive to KCN inhibition than uncoupler stimulated respiration. Fructose, among 20 sugars and sugar alcohols including glucose and mannose, was oxidized with a CO2/O2 ratio of 1.0 by the organism. Iron chelators in general stimulated endogenous respiration, but some of them reduced Fe3+ chemically, introducing complications. The results are discussed in view of a branched electron transport system of the organism and its possible control.Key words: Acidithiobacillus ferrooxidans, endogenous respiration, uncouplers, electron transport.

scholarly journals SOME ENERGY RELATIONS IN A HOST-VIRUS SYSTEM

1953 ◽  
Vol 97 (3) ◽  
pp. 315-322 ◽  
Author(s):  
W. Wilbur Ackermann ◽  
R. Bernal Johnson ◽  
Keyword(s):  
Influenza Virus ◽  
Chorioallantoic Membrane ◽  
Host Tissue ◽  
Endogenous Respiration ◽  
Excellent Correlation ◽  
Viral Propagation ◽  
Twofold Increase ◽  
Energy Relations ◽  
Virus System ◽  
Stimulation Of

It was found that DNP (2,4-dinitrophenol) will inhibit completely the propagation of influenza virus in chorioallantoic membrane. This reagent did not permanently alter those metabolic processes required for the synthesis of virus and at the concentrations employed demonstrated no virucidal effects. In minced preparations of chorioallantoic membrane DNP was shown to have a pronounced stimulatory effect upon ATPase (adenosinetriphosphatase). When DNP was used with intact tissues, an excellent correlation was found between the inhibition of viral propagation and the stimulation of respiration and release of phosphate. Concentrations of DNP which permitted a twofold increase in the endogenous respiration of intact membranes allowed little or no viral synthesis. It is concluded that the energy required for viral synthesis derives from the oxidative phosphorylative activity of the host tissue.

Effect of Magnesium and Calcium Ions on the Photoelectron Transport Activity of Low-Salt Suspended Hydrilla verticillata Thylakoids: Possible Sites of Cation Interaction

1998 ◽  
Vol 53 (9-10) ◽  
pp. 849-856
Author(s):  
Sujata R. Mishra ◽  
Surendra Chandra Sabat
Keyword(s):  
Electron Transport ◽  
Photosystem Ii ◽  
Electron Donor ◽  
Water Oxidation ◽  
Electron Flow ◽  
Hydrilla Verticillata ◽  
Transport Activity ◽  
Low Salt ◽  
Electron Transport Activity ◽  
Stimulation Of

Stimulatory effect of divalent cations like calcium (Ca2+) and magnesium (Mg2+) was investigated on electron transport activity of divalent cation deficient low-salt suspended (LS) thylakoid preparation from a submerged aquatic angiosperm, Hydrilla verticillata. Both the cations stimulated electron transport activity of LS-suspended thylakoids having an intact water oxidation complex. But in hydroxylamine (NH2OH) - or alkaline Tris - washed thylakoid preparations (with the water oxidation enzyme impaired), only Ca2+ dependent stimulation of electron transport activity was found. The apparent Km of Ca2+ dependent stimulation of electron flow from H2O (endogenous) or from artificial electron donor (exogenous) to dichlorophenol indophenol (acceptor) was found to be identical. Calcium supported stimulation of electron transport activity in NH2OH - or Tris - washed thylakoids was electron donor selective, i.e., Ca2+ ion was only effective in electron flow with diphenylcarbazide but not with NH2OH as electron donor to photosystem II. A magnesium effect was observed in thylakoids having an intact water oxidation complex and the ion became unacceptable in NH2OH - or Tris - washed thylakoids. Indirect experimental evidences have been presented to suggest that Mg2+ interacts with the water oxidation complex, while the Ca2+ interaction is localized betw een Yz and reaction center of photosystem II.

EGF promotes gastric mucosal restitution by activating Na+/H+exchange of epithelial cells

2002 ◽  
Vol 282 (5) ◽  
pp. G866-G876 ◽  
Author(s):  
Akinori Yanaka ◽  
Hideo Suzuki ◽  
Takeshi Shibahara ◽  
Hirofumi Matsui ◽  
Akira Nakahara ◽  
...  
Keyword(s):  
Electrical Resistance ◽  
Egf Receptor ◽  
Mucous Cells ◽  
Egf Receptors ◽  
Intracellular Acidosis ◽  
Receptor Antibody ◽  
Epidermal Growth ◽  
Triton X ◽  
Stimulation Of

This study was conducted to determine whether the contributions of epidermal growth factor (EGF) to gastric mucosal restitution after injury are mediated by stimulation of Na+/H+exchangers in surface mucous cells (SMC). Intact sheets of guinea pig gastric mucosae were incubated in vitro. Intracellular pH (pHi) in SMC was measured fluorometrically, using 2′,7′- bis-(2-carboxyethyl)-5-(and-6)-carboxyfluorescein. Restitution after Triton X-100-induced injury was evaluated by recovery of electrical resistance. At neutral luminal pH, exogenous EGF (ex-EGF) increased pHiand enhanced restitution in the absence but not in the presence of serosal HCO[Formula: see text]. During exposure to luminal acid, ex-EGF not only prevented intracellular acidosis but also promoted restitution. These effects of ex-EGF were blocked by serosal amiloride or anti-EGF-receptor antibody. In the absence of ex-EGF, restitution was inhibited by replacement of luminal and serosal solutions with fresh solutions and was blocked more completely by serosal anti-EGF-receptor antibody. These results suggest that both endogenous and ex-EGF contribute to restitution via basolateral EGF receptors, with effects mediated, at least in part, by stimulation of basolateral Na+/H+exchangers.

Stimulation of oxygen uptake by glucagon is oxygen dependent in perfused rat liver

1989 ◽  
Vol 256 (2) ◽  
pp. G369-G376
Author(s):  
Z. Kizaki ◽  
R. G. Thurman
Keyword(s):  
Intracellular Calcium ◽  
High Flow ◽  
Perfused Liver ◽  
Normal Flow ◽  
Sprague Dawley ◽  
O2 Uptake ◽  
Intact Cells ◽  
Flow Rates ◽  
Isolated Mitochondria ◽  
Stimulation Of

Livers from well-fed female Sprague-Dawley rats (100-150 g) were perfused at flow rates of 4 or 8 ml.g liver-1.min-1 to deliver O2 to the organ at various rates. During perfusion at normal flow rates (4 ml.g-1.min-1), glucagon (10 nM) increased O2 uptake in perfused liver by approximately 40 mumol.g-1.h-1. In contrast, glucagon increased O2 uptake by nearly 100 mumol.g-1.h-1 when livers were perfused at high flow rates. Increase in O2 uptake was directly proportional to flow rate and was blocked partially by infusion of phorbol myristate acetate (100 nM) before glucagon. Increase in O2 uptake due to elevated flow was not due to enhanced glucagon delivery, since infusion of 120 nM glucagon at normal flow rates only increased O2 uptake by approximately 40 mumol.g-1.h-1. On the other hand, when O2 tension in the perfusate was manipulated at normal flow rates, the stimulation of O2 uptake by glucagon increased proportional to the average O2 tension in the liver. Infusion of 8-bromo-adenosine 3',5'-cyclic monophosphate (BrcAMP; 25 microM) also increased O2 uptake more than twice as much at high compared with normal flow rates. In the presence of angiotensin II (5 nM), a hormone that increases intracellular calcium, glucagon increased O2 uptake by nearly 100 mumol.g-1.h-1 at normal flow rates. Infusion of glucagon or BrcAMP into livers perfused at normal flow rates increased state 3 rates of O2 uptake of subsequently isolated mitochondria significantly by approximately 25%. In contrast, perfusion with glucagon or BrcAMP at high flow rates increased mitochondrial respiration by 50-60%. Glucagon addition acutely to suspensions of mitochondria, however, had no effect on O2 uptake. These data are consistent with reports that glucagon administration in vivo or treatment of intact cells with glucagon increases O2 uptake of subsequently isolated mitochondria, a phenomenon that can account for the observed increase in O2 uptake in livers perfused at high flow rates with glucagon. Furthermore, these results are consistent with the hypothesis that the effect of glucagon on mitochondria is O2 dependent in the perfused liver. This is most likely due to an effect of intracellular calcium on a mechanism mediated via cAMP.(ABSTRACT TRUNCATED AT 250 WORDS)

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