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PubMed1983

Effects of low concentrations of o(3) on net photosynthesis, dark respiration, and chlorophyll contents in aging hybrid poplar leaves.

Chronic exposure of hybrid poplar (Populus deltoides x trichocarpa) plants to low concentrations of ozone had negative impact upon net photosynthetic capacity, dark respiration, and leaf chlorophyll contents. Exposure to as much as 0.20 microliters per liter O(3) had no immediate effect on net photosynthesis (P(n)), but chronic exposure to 0.125 or 0.085 microliters per liter had a number of gradual effects on CO(2) exchange. These included increased dark respiration and consequently increased light compensation points in very young leaves (4-6 days old); and decreased P(n), leaf chlorophyll a and b contents, light saturation points, and apparent quantum yields in leaves 10 to 70 days old. Decreased P(n) was partially due to accelerated aging in leaves exposed to O(3), and lightsaturated P(n) was linearly related to chlorophyll a + b contents. Differences in light-saturated P(n) between control and O(3)-treated leaves of the same age were mostly due to photosaturation in O(3)-treated leaves and to a much lesser extent to lowered apparent quantum yields. Also, since P(n) and dark respiration were most affected by O(3) at different leaf ages, distinct modes of action are suggested. The effects of leaf aging on CO(2) exchange were considerable, but typical of other species. However, careful monitoring of the interacting effects of leaf age and pollutant exposure was needed in order to characterize the impact of chronic O(3) exposure upon CO(2) exchange.

Journal Article↗
PubMed1984

Experimental determination of the respiration associated with soybean/rhizobium nitrogenase function, nodule maintenance, and total nodule nitrogen fixation.

The total metabolic cost of soybean (Glycine max L. Mer Clark) nodule nitrogen fixation was empirically separated into respiration associated with electron flow through nitrogenase and respiration associated with maintenance of nodule function.Rates of CO(2) evolution and H(2) evolution from intact, nodulated root systems under Ar:O(2) atmospheres decreased in parallel when plants were maintained in an extended dark period. While H(2) evolution approached zero after 36 hours of darkness at 22 degrees C, CO(2) evolution rate remained at 38 degrees of the rate measured in light. Of the remaining CO(2) evolution, 62% was estimated to originate from the nodules and represents a measure of nodule maintenance respiration. The nodule maintenance requirement was temperature dependent and was estimated at 79 and 137 micromoles CO(2) (per gram dry weight nodule) per hour at 22 degrees C and 30 degrees C, respectively.The cost of N(2) fixation in terms of CO(2) evolved per electron pair utilized by nitrogenase was estimated from the slope of H(2) evolution rate versus CO(2) evolution rate. The cost was 2 moles CO(2) evolved per mole H(2) evolved and was independent of temperature.In this symbiosis, nodule maintenance consumed 22% of total respiratory energy while the functioning of nitrogenase consumed a further 52%. The remaining respiratory energy was calculated to be associated with ammonia assimilation, transport of reduced N, and H(2) evolution.

Journal Article↗
PubMed1985

Germination, respiration, and adenylate energy charge of seeds at various oxygen partial pressures.

The effect of O(2) partial pressure on the germination and the respiration of 12 cultivated species was studied. The reciprocal of the time necessary to observe rootlet emergence in 50% of the seeds was used to approach the germination rate. The maximum germination and respiration rates were reached in most seeds at O(2) pressures close to that of air. Decreasing the O(2) pressure produced a gradual decrease of the germination rate. The seeds could be classed in two groups according to their response to low O(2) pressures. Group I includes lettuce, sunflower, radish, turnip, cabbage, flax, and soybean: at O(2) pressures close to 2 kilopascals, the germination in this group was stopped and the adenylate energy charge was lower than 0.6. Group II includes rice, wheat, maize, sorghum, and pea. The germination rate of these seeds was also gradually decreased by lowering the O(2) partial pressure but germination still occured, very slowly, at 0.1 kilopascal; the adenylate energy charge remained higher than 0.6. These differences in the germination rates and adenylate energy charge values could not be explained by differences in the sensitivity of respiration to O(2).

Journal Article↗
PubMed1986

Effects of KCN and Salicylhydroxamic Acid on Respiration of Soybean Leaves at Different Ages.

Measurements of respiration were made on leaf discs from glasshouse-grown soybean (Glycine max [L.] Merr. cv ;Corsoy') plants in the presence and absence of cyanide (KCN) and salicylhydroxamic acid (SHAM). O(2) uptake by mature leaves measured at 25 degrees C was stimulated by 1 millimolar KCN (63%) and also by 5 millimolar azide (79%). SHAM, an inhibitor of the alternative oxidase and a selection of other enzymes, also stimulated O(2) uptake by itself at concentration of 10 millimolar. However, in combination, KCN and SHAM were inhibitory. The rate of O(2) uptake declined consistently with leaf age. The stimulation of O(2) uptake by KCN and by SHAM occurred only after a certain stage of leaf development had been reached and was more pronounced in fully expanded leaves. In young leaves, O(2) uptake was inhibited by both KCN and SHAM individually. The uncoupler, p-trifluoromethoxy carbonylcyanide phenylhydrazone, stimulated leaf respiration at all ages studied, the stimulation being more pronounced in fully expanded leaves. The uncoupled rate was inhibited by KCN and SHAM individually. The capacity of the cytochrome path declined with leaf age, paralleling the decline in total respiration. However, the capacity of the alternative path peaked at about full leaf expansion, exceeding the cytochrome capacity and remaining relatively constant. These results are consistent with the presence in soybean leaves of an alternative path capacity that seems to increase with age, and they suggest that the stimulation of O(2) uptake by KCN and NaN(3) in mature leaves was mainly by the SHAM-sensitive alternative path. The stimulation of O(2) uptake by SHAM was not expected, and the reason for it is not clear.

Journal Article↗
PubMed1988

Cyanide-resistant respiration in light- and dark-grown soybean cotyledons.

Measurements of respiration were made on intact tissue and mitochondria isolated from soybean (Glycine max [L.] Merr. cv ;Corsoy') cotyledons from seedlings of different ages grown in light and darkness. Effects of cyanide (KCN) and salicylhydroxamic acid (SHAM) on O(2) uptake rates were determined. O(2) uptake was faster in light-grown tissue and was inhibited by both KCN and SHAM in all except light-grown tissue older than 9 days. Both inhibitors stimulated O(2) uptake in tissues more than 9 days old. Mitochondria in which O(2) uptake was coupled to ATP synthesis were isolated from all tissues. O(2) uptake by mitochondrial preparations from light- and dark-grown cotyledons was equally sensitive to KCN. Similarly, age did not affect KCN sensitivity, but sensitivity to SHAM declined with age both in the presence and absence of KCN. Estimated capacities of the cytochrome and alternative pathways of the mitochondrial preparations indicated considerably larger cytochrome than alternative pathway capacities. The cytochrome pathway capacities paralleled the state 3 mitochondrial respiration rates, which increased from day 5 to day 7 then declined thereafter. The alternative pathway capacities were not affected by light. The uncoupler, p-trifluoromethoxycarbonylcyanide phenylhydrazone (FCCP), increased the flow of electrons through the cytochrome pathway at the expense of flow through the alternative pathway in isolated mitochondria. However, the combined capacities did not exceed the rate in the presence of FCCP. The results are interpreted to indicate that the stimulation of respiration by KCN and SHAM observed in the 12-day-old green cotyledons and previously observed in older soybean leaves is not explained by characteristics of the mitochondria.

Journal Article↗
PubMed1989

Influence of low temperature on respiration and contents of phosphorylated intermediates in darkened barley leaves.

The aim of this work was to examine the effect of exposure of leaves to low temperatures (5 degrees C) upon the contents of phosphorylated intermediates and respiration in darkened barley (Hordeum vulgare L.) plants which differed in their carbohydrate status. In leaves that had previously been illuminated for 24 hours, there was a large increase in amounts of phosphorylated metabolites at 5 degrees C during the first 3 hours of darkness, compared with control plants kept at 30 degrees C. Hexose phosphates accounted for about two-thirds of this increase, which reached a peak after about 3 hours. At higher temperatures, there was a peak in the amount of fructose 2,6-bisphosphate and the rate of respiration which accompanied the transient increase in phosphorylated intermediates. At 5 degrees C the increase in phosphorylated intermediates was not accompanied by appreciable changes in fructose 2,6-bisphosphate, and there was a rapid decline in the rate of respiration. Leaves that had previously been darkened for 24 hours and that were low in carbohydrate failed to accumulate phosphorylated intermediates when exposed to low temperatures. The results are discussed with respect to the acclimation of carbohydrate metabolism to low temperatures. The results suggest that respiratory carbohydrate metabolism is strictly controlled even when the carbohydrate supply and glycolytic intermediates are abundant. The possibility that accumulation of hexose phosphates may be involved in acclimation of metabolism to low temperature is discussed.

Journal Article↗
PubMed1990

Cytochrome and alternative pathway respiration in green algae : measurements using inhibitors and o(2) discrimination.

Inhibitor titration curves and discrimination against (18)O(2) by mitochondrial respiration in three strains of green algae (Selenastrum minutum [Naeg.] Collins, and two strains of Chlamydomonas reinhardtii Dangeard) with differing respiratory capabilities were determined. Discrimination for cytochrome pathway respiration ranged from 19.89 to 20.43%. Discrimination for alternative pathway respiration by wild-type C. reinhardtii (measured in the presence of KCN) was 25.46%, while discrimination values for a cytochrome oxidase deficient mutant of C. reinhardtii ranged from 24.24 to 24.96%. In the absence of KCN, the alternative pathway was not engaged in wild-type C. reinhardtii, the only algal strain that possessed both cytochrome and alternative pathway capacities.

Journal Article↗
PubMed1991

The Effect of Ethylene and Propylene Pulses on Respiration, Ripening Advancement, Ethylene-Forming Enzyme, and 1-Aminocyclopropane-1-carboxylic Acid Synthase Activity in Avocado Fruit.

When early-season avocado fruit (Persea americana Mill. cv Hass) were treated with ethylene or propylene for 24 hours immediately on picking, the time to the onset of the respiratory climacteric, i.e. the lag period, remained unchanged compared with that in untreated fruit. When fruit were pulsed 24 hours after picking, on the other hand, the lag period was shortened. In both cases, however, a 24 hour ethylene or propylene pulse induced a transient increase in respiration, called the pulse-peak, unaccompanied by ethylene production (IL Eaks [1980] Am Soc Hortic Sci 105: 744-747). The pulse also caused a sharp rise in ethylene-forming enzyme activity in both cases, without any increase in the low level of 1-aminocyclopropane-1-carboxylic acid synthase activity. Thus, the shortening of the lag period by an ethylene pulse is not due to an effect of ethylene on either of the two key enzymes in ethylene biosynthesis. A comparison of two-dimensional polyacrylamide gel electrophoresis polypeptide profiles of in vitro translation products of poly(A(+)) mRNA from control and ethylene-pulsed fruit showed both up- and down-regulation in response to ethylene pulsing of a number of genes expressed during the ripening syndrome. It is proposed that the pulse-peak or its underlying events reflect an intrinsic element in the ripening process that in late-season or continuously ethylene-treated fruit may be subsumed in the overall climacteric response. A computerized system that allows continuous readout of multiple samples has established that the continued presentation of exogeneous ethylene or propylene to preclimacteric fruit elicits a dual respiration response comprising the merged pulse-peak and climacteric peak in series. The sequential removal of cores from a single fruit has proven an unsatisfactory sampling procedure inasmuch as coring induces wound ethylene, evokes a positive respiration response, and advances ripening.

Journal Article↗
PubMed1991

Light-enhanced dark respiration in mesophyll protoplasts from leaves of pea.

The respiratory oxygen uptake by mesophyll protoplasts of pea (Pisum sativum cv Arkel) was stimulated up to threefold after 15 minutes of illumination at an intensity of 1250 microeinsteins per square meter per second in the presence of 5 millimolar bicarbonate at 30 degrees C. The extent of light-enhanced dark respiration (LEDR) increased progressively with duration of preillumination. The LEDR exhibited two phases. The initial high rate of respiration decreased in about 10 minutes to a lower steady value similar to that before illumination. The promotion of LEDR by the presence of bicarbonate and inhibition by glyceraldehyde or 3-(3,4-dichlorophenyl)-1,1-dimethylurea suggested that LEDR was dependent on products of photosynthetic carbon assimilation/electron transport. Thus, the photosynthetic products exert a markedly quick influence on dark respiration in mesophyll protoplasts.

Journal Article↗
PubMed1992

Enhancement of Anaerobic Respiration in Root Tips of Zea mays following Low-Oxygen (Hypoxic) Acclimation.

Root tips (10-millimeter length) were excised from hypoxically pretreated (HPT, 4% [v/v] oxygen at 25 degrees C for 16 hours) or nonhypoxically pretreated (NHPT, 40% [v/v] oxygen) maize (Zea mays) plants, and their rates of respiration were compared by respirometry under aerobic and anaerobic conditions with exogenous glucose. The respiratory quotient under aerobic conditions with 50 millimolar glucose was approximately 1.0, which is consistent with glucose or other hexose sugars being utilized as the predominant carbon source in glycolysis. Under strictly anaerobic conditions (anoxia), glycolysis was accelerated appreciably in both HPT and NHPT root tips, but the rate of anaerobic respiration quickly declined in NHPT roots. [U-(14)C]Glucose supplied under anaerobic conditions was taken up and respired by HPT root tips up to five times more rapidly than by NHPT roots. When anaerobic ethanol production was measured with excised root tips in 50 millimolar glucose, HPT tissues consistently produced ethanol more rapidly than NHPT tissues. These data suggest that a period of low oxygen partial pressure is necessary to permit adequate acclimation of the root tip of maize to subsequent anoxia, resulting in more rapid rates of fermentation and generation of ATP.

Journal Article↗
PubMed1984

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.

Aldehyde Oxidoreductases↗
PubMed1995

Respiration in NREM and REM sleep after upper airway surgery for obstructive sleep apnoea.

To verify whether upper airway surgery in obstructive sleep apnoea syndrome affects differently respiration in NREM and REM sleep, 22 patients were studied by polysomnography before and three months after surgical treatment. On the average, treatment improved respiration during both sleep states, but no significant interaction was found between sleep state and effect of surgical treatment. According to the response to treatment, three groups of patients were identified: the first group (N = 6), with an improvement in apnoea-hypopnoea index (AHI), percentage of sleep time spent in apnoea and hypopnoea (time in AH) and mean oxyhaemoglobin saturation (SaO2) in both NREM and REM sleep; the second group (N = 5), with an improvement in AHI only in NREM sleep, associated with improvement in mean SaO2 in both sleep states; the third group (N = 11), without any improvement in AHI and time in AH, either associated (N = 5) or not (N = 6) with an improvement in mean SaO2 in both sleep states. An increase in the percentage of hypopnoeas out of the total AHI after treatment could partly account for the apparent discrepancy between AHI and mean SaO2 behaviour in the subjects of the second group, but not in the patients of the third group who improved their mean SaO2. Mixed apnoeas occurred before surgery in six subjects; they remained numerous after surgery only in two subjects who did not show any SaO2 improvement. In conclusion, the degree of improvement in respiration after upper airway surgery was similar in every patient in NREM and REM sleep.

Journal Article↗
PubMed1982

Respirators and respiratory care.

The intellectual and technological roots of respirators and respiratory care may be traced back hundreds of years. The clinical evolution has taken the better part of a century, and it has been most closely linked to the development of open-chest surgery. Resuscitation and the treatment of poliomyelitis also have contributed ideas and technology to this evolution. If its successful performance had depended only on respirators, open-chest surgery would have become clinical routine 50-80 years ago. In fact, many factors had to be under control, many modes of treatment had to be available, before the breakthrough in open-chest surgery could occur. The most important factor may have been the effective control of sepsis and hemorrhage. Open-chest surgery forced the change from single-agent deep anesthesia with spontaneous ventilation to a balanced technique, using multiple drugs or agents, with controlled ventilation. Open-chest surgery also necessitated that physicians specialize in anesthesiology. Scandinavian scientists and physicians have contributed greatly to the field of respirators and respiratory care, as has the specialty of anesthesiology.

Anesthesiology↗
PubMed1977

Interaction of glycolysis and respiration in perfused rat liver. Changes in oxygen uptake following the addition of ethanol.

The effect of ethanol on hepatic respiration and glycolysis was studied in perfused rat livers. 1. Ethanol increased the rate of oxygen uptake in livers from fed rats, but decreased the rate in livers from fasted animals perfused in the absence of added substrates. 2. Addition of ethanol decreased the rate of lactate + pyruvate production reflecting an inhibition of glycolysis irrespective of whether glycogen or added glucose was the substrate. 3. Half-maximal stimulation of respiration and inhibition of glycolysis were observed at ethanol concentrations between 0.2 and 0.4 mM. 4. A stoichiometric relationship of one mole of stimulated oxygen uptake to 3.6 mol of decreased lactate + pyruvate production was observed under a variety of experimental conditions. 5. The effects of ethanol on oxygen uptake and lactate + pyruvate production were abolished by the addition of 4-methylpyrazole, an inhibitor of alcohol dehydrogenase, but were unaffected by aminooxyacetate, an inhibitor of hydrogen transport across the mitochondrial membrane. 6. Carboxyatractyloside, an inhibitor of adenine nucleotide translocase, largely abolished the increase in oxygen uptake due to ethnol, but had little effect on the inhibitory action of ethanol on glycolysis. These data indicate that the ethanol-stimulated oxygen uptake is due to an increased flux through the mitochondrial respiratory chain and that it involves the NAD+-dependent oxidation of ethanol by alcohol dehydrogenase. The data are consistent with the hypothesis that the ethanol-stimulated respiration results from an increased demand for mitochondrial oxidative phosphorylation as a consequence of the decreased extramitochondrial ATP generation following inhibition of glycolysis by ethanol.

Aminooxyacetic Acid↗
PubMed1990

Development of the uncoupling protein in the rat brown-adipose tissue during the perinatal period. Its relationship with the mitochondrial GDP-binding and GDP-sensitive ion permeabilities and respiration.

In this paper we report the development of the immunologically detected uncoupling protein (UCP) in brown adipose tissue during the perinatal period in the rat and its relationship with its functional activity expressed in terms of GDP-binding capacity, GDP-sensitive permeabilities and GDP-sensitive respiration. Immunologically detected UCP increased during the last 2 days of foetal life (under euthermic conditions) and after birth (after postnatal hypothermia) during the early suckling period, reaching its maximum value on day 10 after birth. This increase in UCP is accompanied by parallel increases in the GDP-binding capacity, GDP-sensitive permeabilities to protons and chloride ions and GDP-inhibitable respiration. During the suckling--weaning transition, there was a regression of the parameters related to the functional activity of the UCP (GDP-binding capacity and nucleotide-sensitive permeabilities and respiration) without changes in the immunologically detected UCP. These results suggest that the involution of this tissue in the rat commences in this period; the first parameters affected are those related to the functional activity of the UCP while the UCP is still present in its highest level. This seems to support the idea that, in this period of development of the rat, the UCP may exist in the brown fat mitochondria in a functional (unmasked) form and a non-functional (masked) form.

Adipose Tissue, Brown↗
PubMed1994

Antibacterial peptides and mitochondrial presequences affect mitochondrial coupling, respiration and protein import.

Cecropins A and P1, antibacterial peptides from insects and from pig and some related peptides released respiratory control, inhibited protein import and at higher concentrations also inhibited respiration. However, PR-39, an antibacterial peptide from pig intestine, was found to be almost inert towards mitochondria. The concentrations at which the three mitochondrial functions were effected varied for different peptides. Melittin, magainin and Cecropin-A-(1,13)-Melittin(1,13)-NH2, a hybrid between cecropin A and melittin, were most potent, while the two cecropins acted at higher concentrations. The biosynthesis of cecropin A is known and the intermediates are synthesized. We have used four peptides from this pathway to investigate their effects on coupling, respiration and protein import into mitochondria. Mature cecropin A followed by the preproprotein were most aggressive whereas the intermediates were less active or inert. The efficiency of different derivatives of cecropin A as uncouplers correlates well with their capacity to release membrane potential measured as fluorescence quenching of Rhodamine 123. Inhibition of respiration was found to be dependent on membrane potential and was most pronounced with mature cecropin A, less so with its three precursors. We also found that three peptides derived from mitochondrial presequences showed antibacterial activity. It is concluded that, there are similarities in the functions of antibacterial peptides and mitochondrial presequences, uncoupling activity in mitochondria cannot be correlated with the antibacterial activity (contrary to a previous suggestion), the processing of preprocecropin A may have evolved in such a way that there is a minimum of membrane damage from the intermediates in the pathway, and peptides produced for delivery outside of an animal have evolved to be more aggressive against mitochondria than peptides for delivery inside of the animal.

Amino Acid Sequence↗
PubMed1981

Pulmonary complications of long-term respirator care in infants.

Twelve infantile autopsy cases up to 205 days using a long-term respirator care were examined in this study. These cases could be divided into three subgroups. The first group included the cases treated with long-term respirator care for hyaline membrane disease. In this subgroup, bronchopulmonary dysplasia was found during the course. The second group included the cases treated with long-term respirator care for other causes and were very premature infants. In this group, some cases showed bronchopulmonary dysplasia-like lesions. The third group was similar to the second group except for not being very premature. All groups had similar histological changes including alveolar cell desquamation, regeneration of alveolar lining cells, fibrosis, and smooth muscle-like tissue formation of alveolar walls. However, the premature lung tissues remained characteristically in some cases of the second group. In this group, the prematurity of lung was thought responsible for the development of bronchopulmonary dysplasia-like lesion. In addition to bronchopulmonary dysplasia or bronchopulmonary dysplasia-like lesion, other changes including pneumonia, persistent ductus arteriosus, cytomegalic inclusion disease and so forth were discussed.

Bronchi↗
PubMed2005

Rapid decline in nitrate uptake and respiration with age in fine lateral roots of grape: implications for root efficiency and competitive effectiveness.

Changes in function as an individual root ages has important implications for understanding resource acquisition, competitive ability and optimal lifespan. Both nitrate uptake and respiration rates of differently aged fine roots of grape (Vitis rupestris x V. riparia cv. 3309 C) were measured. The resulting data were then used to simulate nitrate uptake efficiency and nutrient depletion as a function of root age. Both nitrate uptake and root respiration declined remarkably quickly with increasing root age. The decline in both N uptake and root respiration corresponded with a strong decline in root N concentration, suggesting translocation of nitrogen out of the roots. For simulations where no nutrient depletion occurs at the root surface, daily uptake efficiency was maximal at root birth and lifetime nitrate uptake efficiency slowly increased as the roots aged. Simulations of growth of roots into unoccupied soil using a solute transport model indicated the advantage of high uptake capacity in new roots under competitive conditions where nitrate availability is very transitory.

Nitrates↗