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

1989 ◽  
Vol 91 (2) ◽  
pp. 603-609 ◽  
Author(s):  
Jonathan D. Monroe ◽  
Thomas A. LaRue
Keyword(s):  
Oxygen Uptake ◽  
Oxygen Concentration ◽  
Nitrogenase Activity

Respiratory metabolism of Azotobacter vinelandii cells at oxygen concentrations that initially range from suboptimal to supraoptimal for nitrogenase activity

1991 ◽  
Vol 37 (4) ◽  
pp. 321-325 ◽  
Author(s):  
Jay B. Peterson
Keyword(s):  
Oxygen Uptake ◽  
Oxygen Concentration ◽  
Azotobacter Vinelandii ◽  
Nitrogenase Activity ◽  
Low Oxygen ◽  
Total Oxygen ◽  
Apparent Affinity ◽  
Lower Oxygen ◽  
Effect Of Oxygen ◽  
Oxygen Concentrations

The effects of three low oxygen concentrations on nitrogenase activity, total oxygen uptake, and respiratory parameters (Vmax and Ks(O2) of N2-grown Azotobacter vinelandii were studied in acetylene reduction assays during a 2-h incubation. The cell suspensions were taken from cultures grown at low aeration. Total oxygen uptake was higher with each increment in oxygen concentration. The highest oxygen concentration was initially supraoptimal for nitrogenase activity. The Ks(O2) values, representing the apparent affinity of the respiration system for oxygen, increased during the incubation of cells at the highest oxygen concentration. The Ks(O2) values at the two lower oxygen concentrations decreased and were very similar. A small effect of oxygen on the Vmax was observed. These results show that the metabolism determining the apparent affinity of the system for oxygen responds to the oxygen concentrations. Furthermore, this metabolism did not substantially increase the Ks(O2) unless the oxygen concentration was high enough to inhibit nitrogenase activity, indicating that the two processes may be linked. Key words: Azotobacter, oxygen regulation, nitrogen fixation.

scholarly journals Diffusion Limitation of Oxygen Uptake and Nitrogenase Activity in the Root Nodules of Parasponia rigida Merr. and Perry

1982 ◽  
Vol 69 (3) ◽  
pp. 728-733 ◽  
Author(s):  
John D. Tjepkema ◽  
Robert J. Cartica
Keyword(s):  
Oxygen Uptake ◽  
Nitrogenase Activity ◽  
Root Nodules ◽  
Diffusion Limitation

scholarly journals Oxygen concentration, nitrogenase activity and heterocyst frequency in the leaf cavities ofAzolla filiculoidesLam

1989 ◽  
Vol 59 (3) ◽  
pp. 283-287 ◽  
Author(s):  
M. Grilli Caiola ◽  
A. Canini ◽  
D. Moscone
Keyword(s):  
Oxygen Concentration ◽  
Nitrogenase Activity ◽  
Heterocyst Frequency

Influence of some factors on oxygen uptake of canine cardiac Purkinje fibers

1963 ◽  
Vol 204 (1) ◽  
pp. 5-8 ◽  
Author(s):  
Kalman Greenspan ◽  
Paul F. Cranefield
Keyword(s):  
Oxygen Uptake ◽  
Oxygen Concentration ◽  
Diffusion Limitation ◽  
Purkinje Fibers ◽  
Ambient Oxygen ◽  
Cardiac Purkinje Fibers ◽  
Lower Oxygen ◽  
Wet Weight ◽  
Oxygen Tensions ◽  
Oxygen Concentrations

The rate of oxygen uptake of quiescent Purkinje fibers of the dog's heart was determined using a flow respirometer and oxygen polarography. At ambient oxygen concentrations of 60% or higher the rate of uptake was 0.739 mm3/mg wet weight per hr at 35 C. The temperature coefficient over the range 25–35° was 2.3. The uptake was independent of the ambient oxygen concentration at oxygen concentrations equal to or greater than 60% of an atmosphere. In lower oxygen concentrations the rate of uptake was found to be depressed. The depression of uptake in the lower oxygen tensions is probably the result of diffusion limitation; it may, however, reflect dependence of resting uptake on oxygen concentration.

scholarly journals Sensitivity to Oxygen of Nitrogenase Activity in Rhizobium Strain ANU289 of the Non-legume Parasponia (Ulmaceae)

1984 ◽  
Vol 37 (2) ◽  
pp. 31 ◽  
Author(s):  
S S Mohapatra ◽  
PM GresshoffA
Keyword(s):  
Carbon Source ◽  
Gas Phase ◽  
Cell Density ◽  
Oxygen Concentration ◽  
Oxygen Tension ◽  
Nitrogenase Activity ◽  
Rhizobium Strain ◽  
Low Oxygen ◽  
Liquid Cultures ◽  
Low Oxygen Tension

Nitrogenase activity can be detected in Rhizobium strain ANU289 of Parasponia in shaken liquid cultures. A combination of consistently low oxygen tension and appropriate cell density was found to be essential for rapid initiation and high specific rates (in the range of 50-60 nmoles of ethylene per milligram protein per hour). In the presence of succinate as carbon source and an oxygen concentration of 0�25% (v/v) in the gas phase, nitrogenase activity developed after incubation for 24 h. The requirement for an oxygen concentration in the range of O� 1 to 0�35% for derepression indicated a lack of any inherent tolerance to higher oxygen levels and thus suggests that plant-derived mechanisms are responsible for protection by oxygen in the nodule.

scholarly journals Effect of Increases in Oxygen Concentration during the Argon-Induced Decline in Nitrogenase Activity in Root Nodules of Soybean

1991 ◽  
Vol 96 (2) ◽  
pp. 376-381 ◽  
Author(s):  
Bryan J. King ◽  
David B. Layzell
Keyword(s):  
Oxygen Concentration ◽  
Nitrogenase Activity ◽  
Root Nodules
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