Effect of cultivation conditions on the activity of respiration of Saccharomyces bayanus]

The effect of sugar and ammonium nitrogen content in the initial nutrient medium as well as the cultivation temperature on the respiration activity and respiratory quotient of yeast used in the champagne manufacture was studied. An addition of ammonium nitrogen stimulated respiratory processes in the yeast cell. The respiration activity increased with an increase of pH to 4.0. With an elevation of the sugar content of the substrate the respiratory quotient increased resulting in an uneconomic utilization of sugar. The maximum respiration activity and minimum respiratory quotient occurred at a temperature of 20 degrees.     

Nippostrongylus brasiliensis and Ascaridia galli: mitochondrial respiration in free-living and parasitic stages

Aerobic respiratory pathways have been delineated and respiratory efficiency has been assessed in mitochondria isolated from embryonated eggs, infective larvae, and adult Nippostrongylus brasiliensis and Ascaridia galli. Mitochondrial respiration in free-living stages of N. brasiliensis is mediated mainly by a mammalian-like antimycin A- and cyanide-sensitive pathway; specific respiratory activity is high and oxidative phosphorylation efficient. In mitochondria of adult N. brasiliensis, antimycin A- and cyanide-sensitive respiration is decreased relative to respiration though an alternative pathway, and specific respiratory activity and mitochondrial efficiency are lower. Respiration in mitochondria from embryonated eggs and tissues of adult A. galli is comparable, and apparently mediated by an antimycin A- and cyanide-insensitive alternative respiratory pathway; no evidence for the presence of a mammalian-like respiratory pathway in embryonated eggs of A. galli was found. The results of this study are compared to mitochondrial respiration in eggs, larvae, and adult body wall muscle of Ascaris suum.     

The effects of parasitism by the plerocercoid of Schistocephalus solidus Muller 1776 (Pseudophyllidea) on the respiration of the three-spined stickleback Gasterosteus aculeatus L.

Rates of oxygen consumption by parasitized and unparasitized sticklebacks were recorded at three levels of activity in February and August. Negative correlations were demonstrated between specific respiratory rates and fish body weights. At routine and maximum activity, infected fish consumed more oxygen than uninfected fish. At minimum activity levels no significant differences in respiration rates were detected. Seasonal variation in respiration rates was attributed to acclimation. Difficulties of determining specific respiration rates for parasitized organisms are discussed and attempts are made to assess the physiological basis of the respiratory and behavioural characteristics of infected fish.     

Stimulation of the cyanide-resistant alternative respiratory pathway by oxygen in Acremonium chrysogenum correlates with the size of the intracellular peroxide pool

The relationship between oxygen input and activity of the cyanide-resistant alternative respiration of submerged cultures of Acremonium crysogenum was investigated. The volumetric oxygen transfer coefficient of the respective cultures correlated positively within almost two ranges of magnitude with the size of the intracellular peroxide pool, which in turn, correlated with the activity of the cyanide-resistant alternative respiratory pathway. Increased aeration also stimulated the glucose uptake rate but had no effect on the total respiration rate or the growth rate. Addition of the lipid peroxyl radical scavenger DL-alpha-tocopherol to A. chrysogenum cultures decreased the rate of intracellular peroxide production as well as glucose uptake. An increase in the cyanide-resistant fraction of total respiration was observed, while growth and the total respiratory activity remained unchanged. We conclude that intracellular peroxides may stimulate the alternative respiration in A. chrysogenum.     

A study of cyanide-insensitive respiration in the genus Dekkera and Brettanomyces

Dekkera intermedia and Brettanomyces custersii were shown to have a respiratory pathway resistant to cyanide, antimycin A, and azide. This respiration remained sensitive to salicylhydroxamic acid (SHAM). The "cyanide-resistant" respiration was induced mainly at the end of the growth phase and could reach 50% of total respiratory capacity. The mitochondrial "petite colony" mutation had no effect on this oxidation pathway. The presence of this respiration pathway in these strains constitutes a compensation mechanism for the reducing activity of acetaldehyde dehydrogenase. This alternate pathway would thus be a fundamental element of the Custer effect, a characteristic feature of these strains.     

The appearance and characterization of cyanide-resistant respiration in the fungus Candida albicans

The respiration of yeast-form cells of the dimorphic fungus Candida albicans became resistant to cyanide during aging treatment in the resting state. An alternative, cyanide-resistant respiratory pathway was found to develop fully in cells aged at a concentration of 0.75 X 10(9)/ml or more at 25 C, but did not appear at 5 C. Chloramphenicol did not prevent the appearance of the alternative respiratory pathway. The effects of inhibitors, salicylhydroxamic acid (SHAM) and disulfiram (tetraethylthiuram disulfide), on respiration of aged cells were examined, and results indicated that SHAM binds at a site on the alternative respiratory pathway whereas disulfiram binds at two sites, one on the conventional respiratory pathway and the other on the alternative pathway. Thus, SHAM is a more selective inhibitor of the alternative respiration of C. albicans cells. SHAM-titration of the alternative respiration revealed that less than 10% of the maximal activity of the alternative respiratory pathway was utilized under normal conditions, indicating that the alternative respiratory pathway makes a small contribution to the total respiration. It was therefore concluded that the alternative, cyanide-resistant respiratory pathway operates fully when the cyanide-sensitive, cytochrome pathway is blocked although aged cells possess both respiratory pathways.     

Respiratory responses induced by the activation of somatic nociceptive afferents in humans.

To further investigate the role of somatic nociceptive afferents in the neural control of breathing, we studied the respiratory effects of their activation by means of either electrical stimulation or ischemic pain in 14 healthy volunteers. Painful electrical cutaneous stimulation increased respiratory frequency (f), mean inspiratory flow (VT/TI), and rate of rise (XP/TI) of integrated electromyographic activity of diaphragm (IEMGdi). Painful muscular electrical stimulation caused similar but larger changes accompanied by increases in tidal volume (VT), peak XP of IEMGdi, and ventilation (VE); it also entrained respiratory rhythm. Ischemic pain, which was characterized by a progressively increasing intensity, caused augmentation in respiratory activity that displayed an increasing trend: VE, f, VT, XP, VT/TI, and XP/TI increased. In the light of available literature, it seems conceivable to suggest that respiratory responses to painful electrical stimulation are mediated through the activation of cutaneous (A delta) and muscular (group III) fine-myelinated afferents, and responses to ischemic pain are mediated by the activation of both fine myelinated (group III) and unmyelinated (group IV) muscular afferents. The input conveyed by these afferents may constitute an effective stimulus to respiration in humans.     

Respiratory activity of Acholeplasma laidlawii cells and its role in the active transport of carbohydrates]

The respiratory activity of the Acholeplasma laidlawii cells was studied in order to elucidate a possible mechanism of coupling of transport with energy. The respiration of the cells is stimulated by ethanol, glucose, NADH, lactate, and pyruvate. The substrates of the Krebs cycle have no effect on the respiration. The respiratory activity, stimulated by ethanol and glucose, is inhibited by the inhibitors of the respiratory chain, SH reagents, and the inhibitors of glycolysis. The results of experiments with inhibitors suggest that the respiratory chain in the A. laidlawii cells is reduced and terminated by flavoprotein. This is confirmed by the results of spectroscopic analysis of cytochromes. Respiration coupled with phosphorylation did not play any important role in the active transport of carbohydrates. Probably, the energy, necessary for the transport of carbohydrates, is supplied by the substrate phosphorylation. This explains the activation of respiration by glucose, which is so sensitive to arsenate. The respiration of the A. laidlawii cells is not stimulated by some carbohydrates (fructose, 3-O-methyl-D-glucose).     

Effect of lipine, a new antihypoxic agent on some respiratory indices in newborn infants after asphyxia]

Lipine, a new antihypoxic drug, has been studied for its effect on respiration and pulmonary gaseous exchange in 47 newborn children, health and with respiratory distress syndrome stresses (SRD) after perinatal asphyxia. It is shown that lipine inhalations cause a considerable increase in duration of respiratory cycle, decrease of respiration frequency, ratio of ispiration di time, to expiration time, increase of alveolar ventilation volume and decrease of respiratory dead space ventilation volume in all lung ventilation volume in newborns with SRD, to a larger degree pronounced in premature children. A conclusion is made on the positive effect of lipine on the state of respiration function and gaseous exchange in lungs in newborn children with symptoms of SRD.     

Contribution of the Phosphorylable Complex I in the Growth Phase-Dependent Respiration of C6 Glioma Cells in Vitro

The energy metabolism of rat C6 glioma cells was investigated as a function of the growth phases. Three-dimensional cultures of C6 cells exhibited diminished respiration and respiratory capacity during the early growth phase, before reaching confluence. This decrease in respiration was neither due to changes in the respiratory complex content nor in the mitochondrial mass per se. Nevertheless, a quantitative correlation was found between cellular respiration and the rotenone-sensitive NADH ubiquinone oxidoreductase (i.e. complex I) activity. Immunoblot analysis showed that phosphorylation of the 18 kDa-subunit of this complex was associated with the growth-phase dependent modulation of complex I and respiratory activity in C6 cells. In addition, by using forskolin or dibutyryl cAMP, short-term activation of protein kinases A of C6 cells correlated with increased phosphorylation of the 18-kDa subunit of complex I, activated NADH ubiquinone oxidoreductase activity and stimulated cellular respiration. These findings suggest that complex I of C6 glioma cells is a key regulating step that modulates the oxidative phosphorylation capacity during growth phase transitions.     

Aberrant energy-linked reactions in mitochondria isolated from the livers of rats infected with the liver fluke Fasciola hepatica.

The respiratory properties of mitochondria isolated from the livers of rats infected with the parasite Fasciola hepatica were examined. Oligomycin-sensitive ATPase activity was also examined during the acute stage (2-4 weeks post-infection). At 2,4 and 6 weeks post-infection, mitochondrial respiration in vitro (supported by site I and site II substrates) was completely uncoupled. Limited respiratory control had returned by 11 weeks post-infection, but complete recovery was not observed even at 21 weeks post-infection. At 4 weeks post-infection, uncoupled respiration (from all three energy-conserving sites) was also markedly attenuated (to the greatest extent with NADH-linked substrate). Except for pyruvate-supported respiration, this attenuation was not apparent at any other stage of the infection. The attenuation of pyruvate-supported respiration declined, but was still present, at 6 weeks post-infection. In addition to these perturbations in mitochondrial respiratory properties, mitochondrial ATPase activity at 4 weeks post-infection was insensitive to oligomycin, indicating a change in the structural integrity of the ATPase complex.     

The effect of total residual chlorine on the respiration rates of two species of freshwater leech (hirudinoidea)

1. The effect of chlorine on the respiration rates of Erpobdella punctata (Leidy) and Nephelopsis obscura (Hirudinoidea) was investigated at total residual chlorine concentrations ranging from 0.00 to 8.00 mg/1 at both 10 and 15C.2. Both species displayed a similar pattern of respiratory response at 10 and 15°C with a decrease in respiration at low chlorine concentrations followed by an increase in respiration at medium concentrations and a decreased respiration rate at high chlorine concentrations.3. The pattern of respiratory response shown by the leeches appears to be related to the differences in activity in different chlorine concentrations.4. The respiration rates of both species were significantly higher at 15°C than at 10°C, but little difference occurred in the respiration response with chlorine concentrations.     

Dynamics of the changes in homogenate respiratory activity after rat whole liver storage at 4 degrees C

Homogenate respiratory activity was studied after different storage terms of the whole rat liver at 4 degrees C in sucrose-based solution and following normothermic reperfusion. Preservation of homogenate respiratory activity in all metabolic states after normothermic reperfusion of the control liver (60 min, 4 degrees C) is shown. Further storage (6 and 24 hrs) of isolated liver under the mentioned above conditions strengthens the substrate respiration of homogenate both after storage and after normothermic reperfusion. At the same time oxidative phosphorylation does not practically change. No change was noted in respiratory activity in the states 3, 4ADP and 3DNP after 24 hrs of liver storage in respect of a previous term. Following normothermic liver reperfusion contributes to a statistically true reduction of mentioned parameters of respiration, that correlates with a decrease in the degree of respiration and phosphorylation coupled of the studied system.     

Regulation of the rate of respiration and oxidative phosphorylation in liver mitochondria from hibernating ground squirrels, Citellus undulatus

1. The rates of oxidation of various substrates (beta-hydroxybutyrate, succinate, ascorbate + TMPD) and the rate of ATP synthesis in liver mitochondria from active and hibernating ground squirrels were measured. 2. It was shown that the rate of mitochondrial respiration is significantly lower in hibernating animals than in active animals. 3. The degree of inhibition of mitochondrial respiration in hibernating ground squirrels was found to correlate with the length of the respiratory chain fragment involved in the oxidation of a given substrate. 4. The inhibition of mitochondrial respiration in hibernating animals was accompanied by a decrease in the rate of ATP synthesis. 5. The activity of phospholipase A2 in liver mitochondria from hibernating ground squirrels was found to be decreased. The activation of phospholipase A2 by Ca2+ ions eliminated the inhibition of respiration almost completely. 6. It was assumed that the inhibition of mitochondrial respiration during hibernation is (a) related to the suppression of phospholipase A2 activity and (b) caused by the reduced rates of electron transport through the respiratory chain and/or of substrate transport across the mitochondrial membrane.     

Respiratory control determines respiration and nitrogenase activity of Rhizobium leguminosarum bacteroids.

The relationship between the O2 input rate into a suspension of Rhizobium leguminosarum bacteroids, the cellular ATP and ADP pools, and the whole-cell nitrogenase activity during L-malate oxidation has been studied. It was observed that inhibition of nitrogenase by excess O2 coincided with an increase of the cellular ATP/ADP ratio. When under this condition the protonophore carbonyl cyanide m-chlorophenylhydrazone (CCCP) was added, the cellular ATP/ADP ratio was lowered while nitrogenase regained activity. To explain these observations, the effects of nitrogenase activity and CCCP on the O2 consumption rate of R. leguminosarum bacteroids were determined. From 100 to 5 microM O2, a decline in the O2 consumption rate was observed to 50 to 70% of the maximal O2 consumption rate. A determination of the redox state of the cytochromes during an O2 consumption experiment indicated that at O2 concentrations above 5 microM, electron transport to the cytochromes was rate-limiting oxidation and not the reaction of reduced cytochromes with oxygen. The kinetic properties of the respiratory chain were determined from the deoxygenation of oxyglobins. In intact cells the maximal deoxygenation activity was stimulated by nitrogenase activity or CCCP. In isolated cytoplasmic membranes NADH oxidation was inhibited by respiratory control. The dehydrogenase activities of the respiratory chain were rate-limiting oxidation at O2 concentrations (if >300 nM. Below 300 nM the terminal oxidase system followed Michaelis-Menten kinetics (Km of 45 +/- 8 nM). We conclude that (i) respiration in R. leguminosarum bacteroids takes place via a respiratory chain terminating at a high-affinity oxidase system, (ii) the activity of the respiratory chain is inhibited by the proton motive force, and (iii) ATP hydrolysis by nitrogenase can partly relieve the inhibition of respiration by the proton motive force and thus stimulate respiration at nanomolar concentrations of O2.     

The effect of substrate, ADP and uncoupler on the respiration of tomato pollen during incubation in vitro at moderately high temperature

Pollen of tomato cv. Supermarmande was collected from greenhouse-grown plants at various intervals throughout the year and arbitrarily classified as of high, medium or low respiratory activity on the basis of CO₂ production during 8 h incubation in vitro at 30°C, a temperature that is considered to be moderately high for tomato fruit set. After an initial burst of respiration during the first stage of hydration at 30°C (>1 h), the respiration rate of pollen of all three categories declined, the decrease being greater in the lots with a low or medium respiratory activity than in the high category. During hydration (10 min after the start of incubation), the addition of succinate or reduced β-nicotinamide adenine dinucleotide (NADH) to the substrate increased the respiratory rate of slowly-respiring pollen more than that of fast-respiring pollen, but carbonyl cyanide 3-chlorophenylhydrazone (CCCP) and adenosine 5′-diphosphate (ADP) had less effect. After 1–4 h incubation, the respiration rate of the slow- or medium-respiring pollen lots had decreased, but was stimulated by succinate or NADH, and to a lesser degree by ADP. By 7 h, the respiration rate of all pollen lots had declined and was stimulated less by substrate, ADP or CCCP. The oxidation of NADH by tomato pollen contrasts with the failure of other pollen species to utilize this substrate; moreover, a synergistic effect of NADH and succinate was consistently observed. We conclude that the decline in respiration during incubation for up to 4 h at 30°C may reflect a lack of respiratory substrate. After 7 h, however, the decreased response to substrate indicates a loss of mitochondrial integrity or an accumulation of metabolic inhibitors. It is concluded that at 30°C (a moderately high temperature for tomato pollen), the initially high rate of respiration leads to exhaustion of the endogenous respiratory substrates (particularly in pollen with low to medium respiratory activity), but subsequently to ageing and a loss of mitochondrial activity.     

Fasciola hepatica: cytochrome c oxidoreductases and effects of oxygen tension and inhibitors

Studies were made on the mechanism of respiration in Fasciola hepatica (Trematoda). Respiration was found to be dependent on the oxygen tension. The respiratory enzyme systems, NADH-cytochrome c oxidoreductase (EC 1.6.2.1), succinate-cytochrome c oxidoreductase (EC 1.3.99.1) NADH oxidase and cytochrome c-oxygen oxidoreductase (EC 1.9.3.1) were detected in a mitochondrial preparation, the NADH oxidase activity being markedly stimulated by addition of mammalian cytochrome c. Amytal and rotenone inhibited NADH oxidase activity. Antimycin A inhibited succinoxidase activity only at relatively high concentrations. Azide was inhibitory at high concentrations. However, cyanide was found to stimulate respiration. Hydrogen peroxide was found to be an end product of respiration in F. hepatica.     

Studies on marine occurring yeasts: Respiration,fermentation and salt tolerance

Summary The effect of various NaCl concentrations on respiration and fermentation rates in cells with or without added glucose as exogenous substrate as well as on respiratory quotients was determined for Debaryomyces hansenii, Saccharomyces cerevisiae, Cryptococcus albidus, and Candida zeylanoides, all yeasts isolated from marine environment. A given strain had about the same respiratory and fermentatory intensity at 0% and 4% NaCl (w/v). A further increase considerably reduced the oxygen uptake or CO₂-evolution. D. hansenii was the most NaCl tolerant yeast tested, giving about 10% activity still at a concentration of 24% NaCl, whether the activities of whole cells or cell homogenates were determined. For S. cerevisiae or Cr. albidus the respiratory activity was reduced to about the same degree at 16% NaCl for whole cells, at 12% NaCl for homogenates of Cr. albidus. A somewhat higher NaCl concentration was evidently tolerated for respiration and fermentation than for growth, very obvious in the case of C. zeylanoides.The minimum values for water activity (a _w) permitting 10% respiration activity were higher when produced by electrolytes (NaCl, KCl, or Na₂SO₄), lower when due to sugars (metabolizable glucose or non-metabolizable lactose) and lowest when due to glycerol. The a _w per se was evidently not solely decisive for the limitation of respiration activity.Attempts were made to assess an effect of high NaCl concentrations on the glucose uptake.The potassium content was higher in cells of the highly halotolerant D. hansenii than in those of the other yeasts and decreased with the increase in external, consequently in internal, Na⁺ concentration. The decrease in K⁺ content can presumably only proceed to a certain extent, below which the ability for growth and respiration was lost.