Oxygen Consumption Curves Research Articles

Influence of aromatic hydrocarbon concentration on character of oxygen-consumption curves

Influence of aromatic hydrocarbon concentration on character of oxygen-consumption curves

Contribution to the study of the effect of copper on Mytilus edulis during reproductive period

Some aspects of copper toxicity in the mussel, Mytilus edulis have been studied. 1. 1. An important acceleration of mortality occurs during the reproductive period. 2. 2. Respiration is similarly aftected. The curves of oxygen consumption obtained with different copper concentrations show that more than one mechanism is upset. 3. 3. The majority of the copper is bound to organic molecules. Accumulation is very high and rapid in the gills. The concentration is also high in the mantle edge and in the foot. After 48 hr, the quantity of metal decreases in all organs. No accumulation organ has been found. 4. 4. Critical concentrations seem to exist which stop some mechanisms. Higher concentrations have no markedly greater effects. 5. 5. The spawning period corresponds with an acceleration of copper uptake and consequently the critical concentration is more rapidly reached.

Sporulation properties of cytochrome a-deficient mutants of Bacillus subtilis.

Three classes of cytochrome a-deficient mutants of Bacillus subtilis have been found to be asporogenic or oligosporogenic. All three classes showed declines in adenosine 5'-triphosphate (ATP) concentrations during early sporulation, at a time when ATP levels in wild-type strains are constant. Class III mutants were found to be deficient in aconitase and isocitric dehydrogenase, and showed reduced maximum growth in nutrient sporulation medium. These mutants also suffered the most rapid decline in ATP concentration in early sporulation, and exhibited neither the biphasic oxygen consumption curve nor the increase in pH normally observed at the end of logarithmic growth in nutrient sporulation medium. Nicotinamide adenine dinucleotide oxidase activities of purified membrane preparations were approximately normal for mutants in all classes, except for two of the class II mutants and one class III mutant. Neither cytochrome a nor cytochrome c appears to be an obligatory intermediate in cyanide-sensitive nicotinamide adenine dinucleotide oxidation in B. subtilis.

Growth curve and rate of oxygen consumption by human glioma cells in culture.

Growth curve and rate of oxygen consumption by human glioma cells in culture.

Control of respiration by the mitochondrial phosphorylation state

The time dependence of oxygen consumption of actively respiring mitochondria has been studied in detail as adenosine diphosphate (ADP) becomes depleted, and the dependence on exogenous adenosine triphosphate (ATP) and orthophosphate (P i) has been investigated. The results are consistent with a model having the electron transport and phosphorylation processes in chemical equilibrium with the extramitochondrial phosphorylation state, [ATP] [ADP] [P i], and the respiration rate proportional to the concentration of reduced cytochrome a 3. The latter is, in turn, dependent upon the phosphorylation state. The mathematical shape of polarographic oxygen consumption curves between the region of excess ADP and the region of minimum ADP has been calculated from the model, and agreement has been found with the experimentally measured rates of oxygen consumption during ADP depletion.

Effect of Perezia pyraustae on oxygen consumption by the European corn borer, Ostrinia nubilalis

Standard Warburg manometric techniques were used to determine the oxygen consumption by European corn borers, Ostrinia nubilalis, infected with Perezia pyraustae and by borers not infected with the protozoan. The curve of oxygen consumption for disease-free corn borers resembled that reported for other Lepidoptera; diseased corn borers had a slightly higher rate of consumption throughout the life cycle.

Decomposition of vanillin by soil microorganisms.

In chernozem soil, vanillin was decomposed via vanillic and protocatechuic acid before the aromatic ring opened. The rate curves of oxygen consumption for the oxidation of vanillin were seen to have more than one maximum. During incubation of the soil with vanillin, the number of bacteria increased, especially those capable of utilizing vanillin as the sole carbon source. Of the 21 such strains isolated, 15 were identified asPseudomonas sp., five asCellulomonas sp. and one asAchromobacter sp. It was found that the course of the oxidation of vanillin varied at different p.H values and in different strains was found that the course of the oxidation of vanillin varied at different p.H values and in different strains of bacteria. In some cases, the phase of the oxidation of vanillin to vanillic acid was clearly differentiated from the subsequent decomposition of vanillic acid.

The oxidation of pipecolic acid in preincubated soils.

Chernozem soil was preincubated with 0.1% glucose, glucose plus ammonium nitrate, hydrolyzed casein or amino acids for five days and with 1% wheat straw, pectin, peptone or cellulose for ten days. The soil was modified by this treatment so that the pipecolic acid was oxidized in two steps, as was shown by two peaks on the graphic plot of the oxygen uptake. In the control soil sample preincubated with water, the oxygen consumption curve formed one peak. In brown soil it was necessary to increase the concentration of glucose and hydrolyzed casein to 1% to obtain the oxidation of pipecolic acid in two phasos. Approximately a third of the oxygen for the complete oxidation of pipecolic acid was consumed in the first phase of oxidation, another third in the second phase of oxidation. A relation was found between the occurrence of the second period of oxidation of pipecolic acid and the amount of organic carbon in the soil.

Automatic assessment of respiration during growth in stirred fermentors.

An apparatus for the continuous and automatic measurement of respiration during growth of micro-organisms in stirred aerated culture is described. The effluent atmosphere from the culture vessels is passed through commercially available oxygen and carbon dioxide gas analyzers, and their electrical output is fed to a multipoint recorder. The apparatus has been used to measure the respiration of Escherichia coli, Pseudomonas aeruginosa, Bacillus thuringiensis, and Methylococcus capsulatus during growth on complex and defined media. In addition, pH values and dissolved oxygen concentrations were measured. Growth of P. thuringiensis in glucose-limited media showed unexpected interruptions in the oxygen consumption curves which resembled diauxic growth; growth of B. thuringiensis in complex media showed similar discontinuities of respiration. These results are explained as the sequential utilization of preferred substrates which, in the case of P. aeruginosa were provided as transient intermediates of glucose.

Automatic Assessment of Respiration During Growth in Stirred Fermentors

An apparatus for the continuous and automatic measurement of respiration during growth of micro-organisms in stirred aerated culture is described. The effluent atmosphere from the culture vessels is passed through commercially available oxygen and carbon dioxide gas analyzers, and their electrical output is fed to a multipoint recorder. The apparatus has been used to measure the respiration of Escherichia coli, Pseudomonas aeruginosa, Bacillus thuringiensis, and Methylococcus capsulatus during growth on complex and defined media. In addition, pH values and dissolved oxygen concentrations were measured. Growth of P. thuringiensis in glucose-limited media showed unexpected interruptions in the oxygen consumption curves which resembled diauxic growth; growth of B. thuringiensis in complex media showed similar discontinuities of respiration. These results are explained as the sequential utilization of preferred substrates which, in the case of P. aeruginosa were provided as transient intermediates of glucose.

FEEDING AND OXYGEN UPTAKE OF THE TROPICAL SEA URCHIN EUCIDARIS TRIBULOIDES (LAMARCK).

1. In the laboratory Eucidaris tribuloides showed a food preference for rock infested with the boring sponge Cliona lampa over turtle grass (Thalassia testudinum), several algae, and fish strips. 2. In the laboratory, urchins consumed wet rock infested with Cliona lampa at rates ranging from less than one to over three gm. per day depending on the size of the urchin. 3. Oxygen consumption of urchins was measured in the laboratory with a modified Scholander volumetric respirometer. 4. Oxygen uptake decreased significantly during the first day of starvation, but then remained relatively stable during several successive days of starvation. 5. There was not a significant correlation between gonad index or sex of the urchin and relative oxygen uptake. 6. Relative oxygen consumption decreased with increasing size of the urchin. Values for "b" indicated an oxygen uptake which was almost proportional to surface area at 20° and 30 ° C. 7. Oxygen uptake fluctuated during the first hour when urchins were placed in water several degrees colder than their ambient water. At the end of this hour, however, the rate of oxygen uptake had become relatively stable. Well-fed urchins manifested greater changes in their stabilized rates of oxygen uptake (Q10) at different temperatures than did starved urchins. 8. Urchins manifested partial seasonal acclimation of oxygen uptake as indicated by the fact that winter oxygen consumption curves were well above summer curves at the corresponding temperatures. The acclimation was probably not complete since mean summer oxygen uptake was higher at the summer ambient than the mean winter oxygen uptake at the winter ambient.

A Theoretical Prediction of the Normal Cardiac Oxygen Consumption

A model is described from which the entropy production associated with the process of transporting oxygen and carbon dioxide between the lungs and the muscles of the body can be calculated. The two entropy sources which are assumed to be the dominant ones for this process are the entropy production associated with the metabolism of the heart and the entropy production associated with the diffusion of oxygen and carbon dioxide into and out of the blood. The hypothesis that the observed blood flow is the one for which a given amount of oxygen and carbon dioxide is transported between the lungs and the muscles with minimum total entropy production is used to predict the value of the slope of the cardiac oxygen consumption vs. blood flow curve. At a blood flow of 15 liters/min, the predicted value of the slope of this curve is 1.2 ml/liter.

Die Bewegungsaktivität der weiblichen Schabe Leucophaea maderae (F.) im Laufe des Fortpflanzungszyklus und ihre experimentelle Beeinflussung

The ovoviviparous cockroach Leucophaea maderae exhibits cyclic motor activity that is correlated with the reproductive cycle. This latter cycle takes about 85 days. The cycle of motor activity is characterized by low activity during pregnancy; a rapid and large increase about 8 days before parturition; medium activity at the beginning of oögenesis. With progressive egg development, the degree of activity gradually decreases until the pregnancy phase is reached again. In its natural environment, the onset of activity of this nocturnal insect is at sunset. Under conditions of constant darkness, the total activity could be clearly subdivided into two components: one regularly distributed over the whole day which was termed ‘basic activity’; the second, strictly periodical, termed ‘circadian activity’. The basic activity component was taken as an indicator of the internal state of excitement. This component is extremely low during the whole period of pregnancy and reaches its peak during the first half of oögenesis (after parturition). The curve of activity resembles the normal curves of oxygen consumption and food consumption. These findings support the hypothesis concerning the activity of the corpora allata. It is possible that the basic activity is enhanced by the c. allata. This has been shown by allatectomy and implantation experiments. However, the results are only statistically weakly significant. Presumably the c. allata effect involves still another system. The circadian activity is superimposed on the basic activity, especially in the 8 day period preceding parturition, but also after optical, mechanical, and acoustical disturbances. It is based on a constant, inborn rhythm of about 24 hr. The rhythmic control of the circadian activity occurs exclusively via nervous pathways originating in the brain. The rapid increase in circadian activity preceding parturation does not occur after cutting the nervous connexions between abdomen and thorax, although circadian behaviour as such may continue. It is therefore concluded that the brain receives information about the state of development of the embryos through the ventral nerve cord. The biological significance of increased motor activity is still unclear. As far as investigated, the circadian rhythmic activity of Leucophaea supports Aschoff's (1964) ideas regarding nocturnal animals.

Der Sauerstoffverbrauch des Facettenauges von Calliphora erythrocephala in Abh�ngigkeit von der Wellenl�nge des Reizlichtes

1. Oxygen consumption curves for the eyes of Calliphora which are adapted to equal-quantum, monochromatic lights are very similar to the spectral efficiency curves of the generator potential. 2. The spectral sensitivity curve for metabolism is approximately the same as the extinction curve of a hypothetical rhodopsin whose λmax=495 nm. 3. The slope of the curve for metabolism vs. relative illumination intensity is steeper in the mutant chalky than in the mutant white. When plotted against the relative quantum level, the metabolism curves for both mutants are the same. 4. The metabolism of eyes simultaneously adapted to two lights of different wave lengths (354 and 508 nm) exceeds the amount one would expect from the simple sum of the two efficiencies.

OXYGEN CONSUMPTION IN FROG SARTORIUS MUSCLE. I. THE ISOMETRIC TWITCH.

AbstractDirect measurements have shown that the heat output from the frog sartorius muscle stimulated under isometric conditions is maximum when the muscle is at reference length and is decreased at stretched and shortened lengths. Experiments were conducted to determine if oxygen consumption following isometric stimulation varied with length in the same manner as did heat.A modified version of a differential volumeter was used consisting of two small sealed chambers each containing one of a pair of frog sartorius muscles. In the presence of a CO2 absorbant extra oxygen consumption is indicated by movement of the index drop toward the chamber containing the stimulated muscle.It was found that at 12°C the oxygen consumption resulting from ten isometric twitches at reference length is 11.93 μ1/g and decreases to 5.10 μ1/g at 0.75 RL and 8.64 μ1/g at 1.25 RL. The absolute value of the oxygen consumption is in agreement with Hill's heat studies using appropriate heat‐oxygen conversion factors. No Feng “stretch response” of an increase in the rate of resting oxygen consumption was observed.Measurements of developed tension were found to parallel the oxygen consumption and heat curves, being 2.28 kg/cm2 at 1.00 RL and decreasing to 1.45 kg/cm2 at 1.25 RL and approaching zero at 0.75 RL.At the shortest lengths the oxygen consumption (5.0 μ1/g) is suggested to represent the equivalent of activation heat since no elastic elements were stretched. Such a suggestion is in agreement with heat studies showing that the energy of activation is approximately half of the maximum initial energy liberated in an isometric contraction.

Etude de la consommation d'oxygene chez Locusta migratoria L.

The oxygen consumption of adults and the last two larval instars of Locusta migratoria has been determined. The oxygen consumption of animals reared in dense populations has been compared with those reared in isolation. The oxygen consumption of the former is greater than the latter. Before and after ecdysis there is no rapid change in oxygen consumption, but during ecdysis oxygen consumption rises abruptly by about 30 per cent. Implanting one pair of adult corpora allata into animals reared in dense populations in the instar before that in which the oxygen consumption was measured did not affect the level of oxygen consumption nor the shape of the oxygen consumption curve. However, the implantation of corpora allata induced a change in pigmentation that caused the hosts to resemble the colour of animals reared in isolation. Injection of thyroxin solutions between 1·4/100,000 and 0·1 mg of thyroxin/g of live animal had no appreciable effect upon the oxygen consumption of animals reared in dense populations.

The influence of juvenile hormone on the oxygen consumption of the last larval instar of Pyrrhocoris apterus L.

Oxygen consumption during the last larval instar of Pyrrhocoris apterus has been studied under the influence of implantations of active corpora allata. The degree of morphological change effected by the juvenile hormone was determined in each specimen after the larval-adult moult. The degree of the induced morphological change is directly proportional to the rate of oxygen consumption. The oxygen consumption curve was practically identical with that of controls until the middle of the intermoult period. The oxygen consumption in the second half of the instar, in which metamorphosis occurs, was less reduced and the period of depression was shorter in specimens that moulted into sixth instar larvae instead of into adults. The intermediates with adultoid characters were intermediate also in this respect. These results are consistent with those of previous work by the authors, according to which the JH-effect on oxygen consumption is an indirect one depending upon increasing the amount of metabolically active tissue.

Oxygen intake curves reflecting circulatory factors in static work.

Oxygen consumption curves were obtained during static exercise on 34 young males. The workloads consisted of 70, 100, 130, and 160 Ibs. resistance. At the onset as well as immediately after the termination of the work period sudden changes of the normal (dynamic exercise) pattern of oxygen consumption were noted and explained in terms of circulatory factors. The linear increase in the “debt/income” ratio (oxygen intake during recovery over oxygen intake during work) with the increase in load shows that the circulation becomes increasingly impaired during static contraction. The metabolic cost of static work must be met by a relatively larger debt payoff during the recovery period.

Physiological comparison of three types of ergometry

A physiological comparison of cycling, cranking and walking has been made, using in all experiments the same subjects and methods. In cycling and cranking energy expenditure increases with work load in a rectilinear way, the energy expenditures being always higher in cranking. In treadmill walking energy expenditure per kilogram of body weight rises curvilinearly both with increasing speed and grade. In cycling, cranking and walking there are nearly the same relations between heart rate and metabolism. Ventilation in cranking always exceeds that in walking and cycling at the same level of oxygen consumption. The curve of ventilation versus oxygen consumption shows a steeper rise in cranking. In level and grade walking ventilation increases curvilinearly with oxygen consumption. Submitted on September 17, 1959

Oxygen Consumption during the Postembryonic Development of Pyrrhocoris Apterus (Heterometabola: Heteroptera), and Its Comparison with That of Holometabola1

While total metabolism in this hemipteron decreases slightly over the whole period of postembryonic development, it shows a definite oscillation in the various nymphal stadia. A more or less pronounced increase in oxygen consumption in the first half-period of each stadium is followed by a decrease during the second, and a new increase, starting just before ecdysis, rises to a peak value immediately after the exuvia is shed. The curve of oxygen consumption during the second halfperiod is like that of pupae of Holometabola, and possible reasons for this similarity are discussed. Physiological processes occurring during the course of a stadium are postulated as being similar in Pyrrhocoris nymphs and in larvae of certain holometabolous insects, with oxygen consumption directly related to intake, digestion, and assimilation of food.