Oxygen Uptake Activity Research Articles

Stabilization of the structure and unctions of a photosystem i submembrane fraction by immobilization in an albumin-glutaraldehyde matrix

The effect of immobilization in an albumin-glutaraldehyde crosslinked matrix on the structure and activity of a photosystem I submembrane fraction has been studied. The photosynthetic activity recovered after immobilization was between 35 and 45% of the oxygen-uptake rates of the native material. Resulting oxygen uptake activities found in immobilized photosystem I preparations with methylviologen as acceptor were as high as 270 μmol O2 (mg Chl h)-1, An enhancement of photosystem I electron transfer, which is produced by incubation of thylakoid membranes at temperatures above 30 °C, was detected in native submembrane fractions, but not in the immobilized preparations. It is suggested that the increased activity at high temperature results from conformational modifications not allowed in the immobilization matrix. The insensitivity of immobilized photosystem I particles to prolonged storage at 4°C and to strong light exposure, as well as their high electron-transfer rates, demonstrates that the immobilization procedure used can be successfully applied to submembrane fractions.

Respiratory Rates and Glycosidase Activities of Juice Vesicles Associated with Section-drying in Citrus

Oxygen uptake and glycosidase activities were examined in normal and granulated juice vesicles of several citrus fruit. Oxygen uptake was low in normal juice vesicles isolated from freshly harvested `Lee' tangelos [Citrus reticulate Blanco cv. Clementine × (Citrus paradisi Macf. cv. Duncan × Citrus reticulate Blanco cv. Dancy)] and stored `Dancy' tangerine (C. reticulate Blanco) and `Marsh' grapefruit (Citrus paradisi Macf.) (35.7, 17.9, and 11.6 μl O2/hr per g fresh weight, respectively), but was 2- to 3-fold higher in granulated juice vesicles. As severity of granulation increased in grape. fruit, O2 uptake increased. Oxygen uptake in normal and disordered juice vesicles of all citrus fruit examined was reduced to nondetectable levels with 0.1 mM KCN and was insensitive to salicylhydroxamic acid. α - and β -galactosidase and α- and β -glucosidase activities were present in extracts of normal grapefruit juice vesicles (123, 214, 51, and 25 nmol·hr-1·g-1 fresh weight, respectively) and was 2- to 3-fold higher in extracts of granulated tissue. α- and β -mannosidase activities, nondetectable in normal juice vesicle extracts, were present in extracts from granulated tissue. The results suggest that increased metabolic activity occurs in granulated juice vesicles and the energy produced may be used to support cell wall synthesis and modification. Increases in O2 uptake and glycosidase activities correlate well with observed symptoms of section-drying in citrus.

Endogenous oxygen uptake and polysaccharide accumulation in Bifidobacterium.

To study the behavior of Bifidobacterium toward oxygen, oxygen uptake was investigated in detail. The cells of Bifidohacterial strains absorbed considerable amounts of oxygen. The exogenous oxygen uptake activity changed depending upon the period of incubation. Bifidobacterial cells also had high endogenous oxygen uptake, which was, in B. longum strains, as high as about 80% of the exogenous oxygen uptake activity. Bifidobacterial cells accumulated considerable amounts of polysaccharide, which was associated with cellular growth. By incubating the cultivated cells in a glucose-free medium, the endogenous oxygen uptake activity was decreased with a decrease of intracellular polysaccharide. Therefore it was postulated that the high endogenous oxygen uptake activity of Bifidobacterium was owing to the metabolism of intracellular polysaccharide. The enzymatic activity, which was involved in the mechanism of oxygen uptake, was also investigated.

The sites of electron donation of Photosystem I to methyl viologen

Effectiveness of methyl viologen as an electron acceptor was studied by oxygen polarography and millisecond time range flash photolysis spectroscopy at room temperature on three types of chloroplast preparation deficient in NADP + photoreduction activity. HgCl 2-treated chloroplasts which had completely lost Fe-S center B and also NADP + photoreduction activity were still partially active in methyl viologen photoreduction. Compared with untreated chloroplasts, V max of the oxygen uptake in this preparation was almost halved and its apparent K m for methyl viologen was about 10 times greater. Photosystem I particles extracted with digitonin from the treated chloroplasts showed, in the absence of methyl viologen, a flash-induced absorption transient at 430 nm whose magnitude and decaying time were very similar to those of the particles extracted from untreated chloroplasts. However, the former required a concentration of methyl viologen for stabilization of P-700 + more than 10 times higher than control particles. The shape of the difference spectrum of the faster decaying component in the presence of methyl viologen was similar to P-430. Our conclusions are: (1) this spectral component represents the redox of Fe-S center A, and chloroplasts can transfer electrons from center X to center A even when their center B is destroyed; (2) center B is the main site of electron donation to methyl viologen, and center A can donate electrons to methyl viologen although with a lower affinity. Chloroplasts anaerobically photoinactivated under strongly reducing conditions in which electron transport between A 0 and center X was impaired showed very low oxygen uptake activity which was almost insensitive to methyl viologen. Dependence of oxygen uptake on methyl viologen concentration by aerobically photoinactivated chloroplasts in which three Fe-S centers were partially destroyed somewhat resembled that of HgCl 2-treated chloroplasts.

Effects of Carbohydrate on the Internal Oxygen Concentration, Oxygen Uptake, and Nitrogenase Activity in Detached Pea Nodules

The interaction between carbon substrates and O(2) and their effects on nitrogenase activity (C(2)H(2)) were examined in detached nodules of pea (Pisum sativum L. cv "Sparkle"). The internal O(2) concentration was estimated from the fractional oxygenation of leghemoglobin measured by reflectance spectroscopy. Lowering the endogenous carbohydrate content of nodules by excising the shoots 16 hours before nodule harvest or by incubating detached nodules at 100 kPa O(2) for 2 hours resulted in a 2- to 10-fold increase in internal O(2), and a decline in nitrogenase activity. Conversely, when detached nodules were supplied with 100 millimolar succinate, the internal O(2) was lowered. Nitrogenase activity was stimulated by succinate but only at high external O(2). Oxygen uptake increased linearly with external O(2) but was affected only slightly by the carbon treatments. The apparent diffusion resistance in the nodule cortex was similar in all of the treatments. Carbon substrates can thus affect nitrogenase activity indirectly by affecting the O(2) concentration within detached nodules.

Seed Germination Rate and Associated Characters in Rice

Rapid seed germination will facilitate quick plant stand establishment in direct sown rice (Oryza sativa L.) culture. Sixty‐eight rice cultivars were grown in the field and in the phytotron, and the harvested seed evaluated for germination rate. Cultivars ‘Laxmi’, TNAU(AD)103, IR25924‐92‐1‐3, ‘IR50’, PND160‐2‐1, RNR1429, IR31779‐19‐3‐3‐2‐2, and B3981c‐Pn‐165‐2‐l produced seeds in the field and the phytotron that exhibited superior performance. Therefore, these could be useful donor parents for promoting rapid seed germination when breeding rice for direct‐sown culture. One hundred seed weight was negatively correlated with germination rate. Path analysis suggested that 100 seed weight acted through a high indirect effect of free amino acid content on germination rate. Oxygen uptake and dehydrogenase activity also contributed to germination rate variability. Cultivar differences were evident for germination rate following aging and under low temperature (20 and 15 °C) and moisture stress (−5̄ polyethylene glycol 8000). Hulls did not contribute to variability in germination rate.

The Relationship between Peak Oxygen Uptake and Physical Activity in 6- to 8-Year-Old Children.

The relationship between physical activity measured using the LSI (Large Scale Integrated Activity Monitor), and questionnaire, with physical work capacity 170 (PWC 170) and aerobic capacity (peak V̇O2) was evaluated in 6- to 8-year-old children (n = 18). The mean (± SD) peak V̇O2 was 44.1 ± 5.6 ml • kg-1 • min-1. Peak V̇O2 was not significantly different for children (n = 8) who had completed two treadmill trials (45.4 vs. 43.5 ml • kg-1 • min-1; R = 0.67, p>0.05). The log LSI expressed as counts per hour (M ± SD = 2.1 ±.22 cts/hr) was the only activity method significantly related to peak V̇O2 (r = 0.59, p>0.05). The correlation between peak V̇O2 with the questionnaire was positive but nonsignificant (r = 0.20). PWC 170 was not related to peak V̇O2 (r = 0.21) or the activity variables (r = 0.12 questionnaire; r = 0.18 log LSI). When the group was divided into high and low peak V̇O2 groups (high: M = 48.8 ml • kg-1 • min-1; low: M = 39.5 ml • kg-1 • min-1), the log LSI was able to distinguish significant differences in activity levels (high: 2.23 ±. 19 cts/hr; low: 1.99±.19 cts/hr). This study suggests that activity measured with the LSI and aerobic capacity are related in this sample of 6- to 8-year-old children.

Effects of Organic Nutrient Strength on the Purple Nonsulfur Bacterial Content and Metabolic Activity of Photosynthetic Sludge for Wastewater Treatment

Changes in the purple nonsulfur bacterial content and metabolic activity of photosynthetic sludge in response to wastewater strength in a practical plant and in laboratory-scale batch reactors were investigated. Both plant and laboratory systems yielded large quantities of purple nonsulfur bacteria, as many as 10 7 viable cells·mg dry sludge −1, when loaded with high biological oxygen demand (BOD) levels of wastewater containing acetate as a major BOD source. Experiments with laboratory reactors showed that the phototrophic bacteria could keep occurring in such large numbers at BOD-loading rates higher than 0.8 kg BOD·kg dry sludge −1·d −1. The loading of high BOD wastewater also enhanced oxygen uptake activity with lower fatty acids used as substrates, as well as the enzyme activities of the tricarboxylic acid cycle of the sludge. However, there was no difference in the enzyme activities of the glyoxylate pathway between high BOD-loaded and low BOD-loaded sludges. The results obtained suggest that wastewater strength, especially a lower fatty acid concentration, is one of the most important factors affecting the viability and activity of purple nonsulfur bacteria in the photosynthetic sludge process.

Possible influence of Rhizobium on VA mycorrhiza metabolic activity in double symbiosis of alfalfa plants (Medicago sativa L.) grown in a pot experiment

Alfalfa (Medicago sativa, L. cv Aragon) plants were grown under greenhouse conditions in pots of inert sand and vermiculite. The plants were inoculated with Rhizobium meliloti strain 102F28, with Glomus fasciculatus or with a mixture of both microorganisms. Plants inoculated with both Rhizobium and Glomus had the highest shoot dry weight and the lowest root-to-shoot ratio. Roots from dually inoculated plants also had a higher oxygen uptake and nodule nitrogenase activity than those from plants inoculated with either of the two microsymbionts alone. However, the dry weight of the roots from only VAM-infected plants was higher than those from Rhizobium or from Rhizobium plus Glomus-inoculated ones. These differences did not correlate with succinate dehydrogenase activity, which was similar between treatments. Nutrient element concentrations were increased in dually infected plants in comparison with those of plants inoculated with only Rhizobium or Glomus. These data suggest that Rhizobium may affect fungal metabolism and that the effect is not achieved via the tricarboxylic acid pathway.

Temporal separation of nitrogen fixation and photosynthesis in the filamentous, non-heterocystous cyanobacterium Oscillatoria sp.

When growing in laternating light-dark cycles, nitrogenase activity (acetylene reduction) in the filamentous, non-heterocystous cyanobacterium Oscillatoria sp. strain 23 (Oldenburg) is predominantly present during the dark period. Dark respiration followed the same pattern as nitrogenase. Maximum activities of nitrogenase and respiration appeared at the same time and were 3.6 μmol C2H4 and 1.4 mg O2 mg Chl a-1·h-1, respectively. Cultures, adapted to light-dark cycles, but transferred to continuous light, retained their reciprocal rhythm of oxygenic photosynthesis and nitrogen fixation. Moreover, even in the light, oxygen uptake was observed at the same rate as in the dark. Oxygen uptake and nitrogenase activity coincided. However, nitrogenase activity in the light was 6 times as high (22 μmol C2H4 mg Chl a-1·h-1) as compared to the dark activity. Although some overlap was observed in which both oxygen evolution and nitrogenase activity occurred simultaneously, it was concluded that in Oscillatoria nitrogen fixation and photosynthesis are separated temporary. If present, light covered the energy demand of nitrogenase and respiration very probably fulfilled a protective function.

Numerical characterization of forest soils using biological and biochemical properties

To find if surface soils could be grouped by their biological and biochemical properties, soil samples (0–5 cm) were collected at 4-week intervals for 56 weeks from 48 woods in and around the English Lake District, and pH, loss-on-ignition (LOI), moisture content, oxygen uptake, and cellulase and phosphatase activities were measured. Results expressed on a loss-on-ignition basis were more informative than those on an oven-dry basis. In a principal component analysis of each property over the 14 samplings, the first component values represent “smoothed” between-plot differences; other components identify plots which behave differently from the majority at certain times. Analysis of variance showed very highly significant differences between plots for all the properties. pH and loss-on-ignition showed the smallest, but significant, differences between samplings. On a loss-on-ignition basis, the only significant correlations between first component values, and between plot means, were phosphatase with oxygen uptake and cellulase with pH. It is concluded that no individual physiological property can be used as a measure of soil bioactivity, which supports the conclusions of other authors. None of the principal component analyses of individual or combined properties showed any evidence of the existence of distinct clusters of plots. On a loss-on-ignition basis, a priori groups based on (1) pH 5.0, showed no significant difference in moisture content. However, oxygen uptake was significantly lower in (1) than in (2). Cellulase activity was significantly greater in (3) than in (1) and (2). Phosphatase activity was significantly lower in (1) than in (2), and there appeared to be a peak at pH 3.8 – 5.0.

Biosynthesis of superoxide dismutase and catalase in chemostat culture of Saccharomyces cerevisiae

The effects of oxygen (100%), paraquat (0.5 mM), and copper (0.1 mM) on the growth and the biosynthesis of the antioxidant enzymes, superoxide dismutase (SOD) and catalase, were studied in Saccharomyces cerevisiae grown in glucose-limited chemostat cultures. The effect of dilution rates (D, h−1) on cell mass, glucose consumption, ethanol production, oxygen uptake, and specific activities of SOD and catalase were also investigated at each steady state. SOD was optimally produced at D-values between 0.22 and 0.26 h−1 in the presence of oxygen or paraquat, and at D-values greater than 0.17 h−1 when copper was used. On the other hand, catalase activity decreased with increasing D-values. However, the presence of copper or 100% oxygen repressed catalase activity at low D-values (D 0.22 h−1). We also studied the effect of oxygen concentration on the biosynthesis of SOD and catalase at D=0.1 h−1. The data clearly show that synthesis of SOD and catalase, though correlated with changes in oxygen tension, are independent of one another.

The effect of cadmium on starved heterotrophic bacteria isolated from marine waters

The effect of Cd2+ on two starved marine Gram-negative bacteria, S14 and DW1, was examined. Viability, total numbers, the inhibition of DNA and protein synthesis, uptake of leucine and thymidine and oxygen consumption were measured. The cells were exposed to Cd2+ during the initial phase of starvation in nutrient-free artificial sea water. Short-term starved cells tolerated Cd2+ at concentrations as high as 1.4/ μM. The exposure of DW1 and S14 cells to 70 μM and 140 μM, respectively, immediately prevented the initial increase in number, typical of the starvation survival response of these cells. The viability was tested both with a direct quantification of the proportion of respiring cells by using 2-( p -iodophenyl)-3( p -nitrophenyl)-5 phenyltetrazolium chloride (INT), and the proportion of colony-forming units grown on agar plates. Treatment with Cd2+ caused a loss in the capacity to form colonies on agar plates rather than a loss in viability. The proportion of respiring cells always exceeded the proportion of colony-forming units. Initial Cd2+ exposure gave a rapid inhibition of the incorporation of [3H]thymidine into DNA, while oxygen consumption, protein synthesis and uptake activities were less affected. More than 1 h of Cd2+ incubation, however, caused a pronounced inhibition of all the metabolic parameters examined. Cadmium-exposed cells recovered the ability to proliferate when incubated in Cd2+-free nutrient broth. 24 h Cd2+-exposed cells increased the respiration rate immediately when incubated in Cd2+- free broth but proliferation and [3H]thymidine incorporation were not seen prior to a lag period of 7–8 h. Starved, previously Cd2+-exposed cells which were incubated in a Cd2+-free starvation regimen gradually regained their colony-forming capacity. The increase in the number of colonyforming units in the starvation regimen occurred without a concomitant increase in cell numbers.

Oxygen Uptake Activity and Aerobic Metabolism of Streptococcus thermophilus STH450

Streptococcus thermophilus STH450 had a very high oxygen uptake. This strain was then compared with aerobic metabolism to S. thermophilus ATCC 19258, a reference strain for aerobic metabolism. Molecular oxygen, which was absorbed by S. thermophilus STH450 during aerobic glycolytic metabolism, was involved in the oxidation of NADH by the catalytic activity of NADH oxidase. The portion of pyruvate that corresponded to the oxidized NADH was committed to form α-acetolactate, acetoin, and diacetyl. Both strains were deficient in peroxidase and pyruvate oxidase activities; therefore, NADH oxidase was probably the terminal oxidase in aerobic glycolytic metabolism. Oxygen uptake and NADH oxidase activities were significantly higher in S. thermophilus STH450 than in S. thermophilus ATCC 19258. α-Acetolactate, acetoin, and diacetyl also accumulated during aerobic glycolytic metabolism of S. thermophilus STH45O. However, when both strains were grown in the presence of pyruvate, these metabolites were equivalent. Hence, less oxygen might be needed for pyruvate metabolism.

Endurance training does not affect diaphragm mitochondria respiration

We sought to determine if chronic endurance training would increase mitochondrial respiration or protein content in rat diaphragm muscle. To this end, 20 male Wistar rats were randomly assigned to control (C) or an 8-week endurance training (T) group, n = 10 per group. At the end of T, V̇ O 2 max was 13% greater in T (83.3 vs 73.8 ml·kg −1·min −1) and peak max power output was 32% greater (2.63 vs 1.98 kg·m·min −1). Mitochondrial specific activities of pyruvate-malate and cytochrome oxidase (expressed per mg mitochondrial protein) in both plantaris and diaphragm were similar in C and T rats, as were ADP/O and respiratory control ratios. When expressed per gram wet weight, whole muscle homogenate oxygen uptake (pyruvate + malate) and cytochrome oxidase activity increased 36 and 23%, respectively ( P < 0.05) in plantaris from T rats but did not change in diaphragm. Control oxidative capacity and mitochondrial protein content in the diaphragm were ca. 2-fold those in control plantaris. Plantaris mitochondrial protein content increased ca. 50% with T while the diaphragm was unaffected. We conclude that: (1) plantaris muscle oxidative capacity adapts to training by increasing mitochondrial protein content, since there was no evidence for functional improvement of existing mitochondria, and (2) in the face of a substantial training effect in whole animal and plantaris, the T stimulus was not sufficient to induce mitochondria protein changes in the diaphragm. This finding is the result of either a ‘pre-adaptation’ secondary to the diaphragm's high chronic activity, or a sub-threshold increase in diaphragn recruitment during the exercise conditions studied.

Maximal oxygen uptake, anthropometry and physical activity in a randomly selected sample of 8 and 13 year old children in Sweden.

Maximal oxygen uptake was assessed in 101 randomly selected 8 and 13 year old children. In both age groups a significantly higher aerobic capacity was found in boys than in girls, both in absolute terms and when maximal oxygen uptake was related to body weight, lean body mass and lean leg volume. Among girls, maximal oxygen uptake per kg body weight was lower in the older than in the younger (p less than 0.05). Estimation of spontaneous physical activity, by means of a questionnaire and the actometry method, indicated that physical activity was greater in children with a high than in those with a low aerobic capacity.

Comparison of oxygen microgradients, oxygen flux rates and electron transport system activity in coastal marine sediments : Andersen, F.Ø. and Willem Helder, 1987. Mar. Ecol.-Prog. Ser., 37(2–3):259–264

Oxygen profiles, actual oxygen uptake and electron transport system activity (ETSA) were studied in 4 intertidal sedirnents at Texel, NW Netherlands. Organic carbon content ranged from 0.02 to 0.4 O/ O dry weight. Profiles of oxygen were recorded with a needle minielectrode and showed that oxygen was present down to 18 mm in the sandy beach sediment with low carbon content, whereas oxygen only penetrated down to 1 to 3 mm in the organically richer sediments. Measured oxygen uptake ranged from 395 to 2315 pm01 O2 m-' h ' and exceeded oxygen uptake estimated on basis of molecular diffusion by 1.4 to 3.2 times. The difference between the 2 methods for measuring oxygen uptake indicates that bottom fauna activity significantly contributes to the sediment-water exchange of oxygen. The ETSA varied from 0.02 to 0.81 pm01 0, g-' h ' The ETSA at the sediment surface was positively correlated to sediment oxygen uptake. Nelther ETSA nor oxygen uptake showed correlation to organic carbon or nitrogen content in the sediment.

Comparison of oxygen microgradients, oxygen flux rates and electron transport system activity in coastal marine sediments

Oxygen profiles, actual oxygen uptake and electron transport system activity (ETSA) were studied in 4 intertidal sedirnents at Texel, NW Netherlands. Organic carbon content ranged from 0.02 to 0.4 O/ O dry weight. Profiles of oxygen were recorded with a needle minielectrode and showed that oxygen was present down to 18 mm in the sandy beach sediment with low carbon content, whereas oxygen only penetrated down to 1 to 3 mm in the organically richer sediments. Measured oxygen uptake ranged from 395 to 2315 pm01 O2 m-' h ' and exceeded oxygen uptake estimated on basis of molecular diffusion by 1.4 to 3.2 times. The difference between the 2 methods for measuring oxygen uptake indicates that bottom fauna activity significantly contributes to the sediment-water exchange of oxygen. The ETSA varied from 0.02 to 0.81 pm01 0, g-' h ' The ETSA at the sediment surface was positively correlated to sediment oxygen uptake. Nelther ETSA nor oxygen uptake showed correlation to organic carbon or nitrogen content in the sediment.

Growth of Non-Sulfur Purple Photosynthetic Bacteria under High Temperature

Four strains of non-sulfur purple photosynthetic bacteria isolated in the Bangkok area, Thailand, grew at 40 and 45°C under photosynthetic and strict anaerobic conditions. At higher temperature of 45°C, the bacteria did not grow under sealing with liquid paraffin. On the other hand, the organisms grew at 45°C, when they were allowed to grow as mixed culture with a strict aerobic bacterium, designated as 22 TW-S, under sealing with liquid paraffin. The respiratory activities of TR-22R-B, one of the isolated photosynthetic bacteria, and 22 TW-S were examined at 40 and 45°C. The oxygen uptake activities of 22 TW-S at 40 and 45°C were about 18 and 4 times higher than those of TR-22R-B, respectively, when DL-malate was used as a substrate. The redox-potential of the culture medium which permitted the initiation of growth of TR-22R-B was found to be much lower at 45°C than at 40°C. It was assumed that 22 TW-S acted as an oxygen scavenger under sealing with liquid paraffin, and thus established favorable conditions for growth of TR-22R-B.

Oxygen uptake activity byNitrobacterspp. in the presence of metal ions and sulfooxyanions

Several metal ions inhibited the oxygen uptake activity of Nitrobacter agilis, but their effects on the kinetic parameters of nitrite oxidation were mixed. Growth of Nitrobacter winogradskyi was inhibited by persulfate (> 0.1 mM), tetrathionate (> 0.5 mM), and trithionate (> 5 mM). Oxygen uptake activity was, however, relatively insensitive to persulfate and tetrathionate ions.