scholarly journals Control of respiration and metabolism in growing Klebsiella aerogenes. The role of adenine nucleotides

1969 ◽  
Vol 112 (5) ◽  
pp. 647-656 ◽  
Author(s):  
D. E. F. Harrison ◽  
P. K. Maitra
Keyword(s):  
Steady State ◽  
Respiration Rate ◽  
Chemostat Culture ◽  
Adenine Nucleotides ◽  
Sampling Technique ◽  
Turnover Time ◽  
Atp Content ◽  
Rapid Sampling ◽  
State Growth ◽  
Limited Culture

1. A rapid-sampling technique was used to obtain perchloric acid extracts of cells growing in a chemostat culture, so that meaningful values for ATP content could be obtained in spite of the fact that the turnover time for the total ATP content was about 1sec. 2. For steady-state growth, it was found that, in a glucose-limited chemostat culture, the ATP/ADP concentration ratio was approximately constant with changes in dissolved-oxygen tensions above the critical value, but fell when the culture was grown under oxygen-limited conditions and was at a minimum in anaerobically grown cultures. The steady-state ATP content was lower in cells growing under nitrogen-limited conditions with glucose in excess than in glucose-limited cells. The steady-state ATP content was independent of growth rate at growth rates over 0·1hr.−1. 3. When the respiration rate of the cells was stimulated by lowering the oxygen tension the ATP content did not increase, indicating either an increased turnover rate of ATP or a fall in the P/O ratio. The sudden addition of extra glucose or succinate to a glucose-limited culture increased the respiration rate of the cells, but the ATP content quickly returned to the steady-state value after initial perturbations. This control over ATP content is explained in terms of regulation by adenine nucleotides of the catabolism and anabolism of glucose. An exception to this control over ATP content was found when the respiration rate was stimulated by addition of an antifoam.

Validation of On-line Respiration Meter and its Applications by Computer Simulation

1992 ◽  
Vol 26 (5-6) ◽  
pp. 1355-1363 ◽  
Author(s):  
C-W. Kim ◽  
H. Spanjers ◽  
A. Klapwijk
Keyword(s):  
Steady State ◽  
Activated Sludge ◽  
Respiration Rate ◽  
Oxygen Demand ◽  
Operating Conditions ◽  
Mass Balances ◽  
Short Term ◽  
Respiration Rates ◽  
On Line ◽  
Made In

An on-line respiration meter is presented to monitor three types of respiration rates of activated sludge and to calculate effluent and influent short term biochemical oxygen demand (BODst) in the continuous activated sludge process. This work is to verify if the calculated BODst is reliable and the assumptions made in the course of developing the proposed procedure were acceptable. A mathematical model and a dynamic simulation program are written for an activated sludge model plant along with the respiration meter based on mass balances of BODst and DO. The simulation results show that the three types of respiration rate reach steady state within 15 minutes under reasonable operating conditions. As long as the respiration rate reaches steady state the proposed procedure calculates the respiration rate that is equal to the simulated. Under constant and dynamic BODst loading, the proposed procedure is capable of calculating the effluent and influent BODst with reasonable accuracy.

Reduced substrate oxidation in postischemic myocardium: 13C and 31P NMR analyses

1990 ◽  
Vol 258 (5) ◽  
pp. H1357-H1365 ◽  
Author(s):  
E. D. Lewandowski ◽  
D. L. Johnston
Keyword(s):  
Steady State ◽  
31P Nmr ◽  
Tca Cycle ◽  
High Energy ◽  
Substrate Oxidation ◽  
High Energy Phosphates ◽  
Atp Content ◽  
And Control ◽  
13C And 31P Nmr ◽  
Postischemic Myocardium

13C and 31P nuclear magnetic resonance (NMR) spectra were used to assess substrate oxidation and high-energy phosphates in postischemic (PI) isolated rabbit hearts. Phosphocreatine (PCr) increased in nonischemic controls on switching from glucose perfusion to either 2.5 mM [3-13C]pyruvate (120%, n = 7) or [2-13C]acetate (114%, n = 8, P less than 0.05). ATP content, oxygen consumption (MVO2), and hemodynamics (dP/dt) were not affected by substrate availability in control or PI hearts. dP/dt was 40-60% lower in PI hearts during reperfusion after 10 min ischemia. Hearts reperfused with either pyruvate (n = 11) or acetate (n = 8) regained preischemic PCr levels within 45 s. Steady-state ATP levels were 55-70% of preischemia with pyruvate and 52-60% with acetate. Percent maximum [4-13C]glutamate signal showed reduced conversion of pyruvate to glutamate via the tricarboxylic acid (TCA) cycle at 4-min reperfusion (PI = 24 +/- 4%, means +/- SE; Control = 48 +/- 4%). The increase in 13C signal from the C-4 position of glutamate was similar to control hearts within 10.5 min. The increase in [4-13C]glutamate signal from acetate was not different between PI and control hearts. The ratio of [2-13C]Glu:[4-13C]Glu, reflecting TCA cycle activity, was reduced in PI hearts with acetate for at least 10 min (Control = 0.76 +/- 0.03; PI = 0.51 +/- 0.09) until steady state was reached. Despite rapid recovery of oxidative phosphorylation, contractility remained impaired and substrate oxidation was significantly slowed in postischemic hearts.

Kinetics of the cytochrome c oxidase and reductase reactions in energized and de-energized mitochondria

1977 ◽  
Vol 55 (7) ◽  
pp. 706-713 ◽  
Author(s):  
Lars Chr. Petersen ◽  
Hans Degn ◽  
Peter Nicholls
Keyword(s):  
Steady State ◽  
Cytochrome C ◽  
Cytochrome C Oxidase ◽  
Oxygen Concentration ◽  
Respiration Rate ◽  
Redox State ◽  
Rat Liver Mitochondria ◽  
Excess Oxygen ◽  
Succinate Oxidation ◽  
State Reduction

1. Coupled, cytochrome-c-depleted ('stripped') rat liver mitochondria reducing oxygen in the presence of exogenous cytochrome c, with succinate or ascorbate as substrates, show marked declines in the steady-state reduction of cytochrome c in excess oxygen on addition of uncouplers. Calculated ratios of maximal turnover in the uncoupled state and in the energized state for the cytochrome c oxidase (EC 1.9.3.1) reaction lie between 3 and 6, as obtained with reconstituted oxidase-containing vesicles. The succinate-cytochrome c reductase activity in such mitochondria shows a smaller response to uncoupler than that of the oxidase.2. The respiration rates of uncoupled mitochondria oxidizing ascorbate in the presence of added cytochrome c follow a Michaelis–Menten relationship with respect to oxygen concentration, in accordance with the pattern found previously with the solubilized oxidase. But succinate oxidation tends to give nonlinear concave-upward double-reciprocal plots of respiration rate against oxygen concentration, in accordance with the pattern found previously with intact uncoupled mitochondria.3. From simultaneous measurements of cytochrome c steady-state reduction, respiration rate, and oxygen concentration during succinate oxidation under uncoupled conditions it is found that at full reduction of cytochrome c, apparent Km for oxygen is 0.9 μM and the maximal oxidase (aa3) turnover is 400 s−1 (pH 7.4, 30 °C).4. The redox state of cytochrome c in uncoupled systems reflects a simple steady state; the redox state of cytochrome c in energized systems tends towards an equilibrium condition with the terminal cytochrome a3, whose apparent potential under these conditions is more negative than that of cytochrome c.

Effect of growth rate on the physiological rates of a chemostat-grown rotifer Encentrum linnhei

1988 ◽  
Vol 68 (1) ◽  
pp. 165-177 ◽  
Author(s):  
J. M. Scott
Keyword(s):  
Growth Rate ◽  
Oxygen Consumption ◽  
Steady State ◽  
Respiration Rate ◽  
Clearance Rate ◽  
Ingestion Rate ◽  
Physiological State ◽  
Growth Efficiency ◽  
Theoretical Figure ◽  
Marine Rotifer

The physiological rates of a normally omnivorous marine rotifer, Encentrum linnhei, were measured under the steady-state chemostat conditions in which the physiological state of the food-algae was kept constant whilst the rotifer growth rate was changed to preset levels. The specific clearance rate ranged between 50 and 100 μl/μg rotifer C/day (1.5–3.0 μ/rot/day) and varied hyperbolically with growth rate, a similar curve was obtained with the specific ingestion rate which varied between 1–2 μg C/μg rot C/day. A mean respiration rate of 0.45 μg C/μg rot C/day was obtained from oxygen consumption measurements. About 60‰ of ingested energy was found to be egested as paniculate matter and 9–4 °0 dissipated as heat, the latter comparing with a theoretical figure of 4–5‰.From rates, transfer efficiencies were obtained giving a mean net growth efficiency (K2) of 38‰ and a mean overall growth efficiency (K1 of 15‰. A curvilinear increase of Kl with growth rate contrasts with linear and hyperbolic responses found with brachionid rotifers.

scholarly journals Ecosystem carbon transit versus turnover times in response to climate warming and rising atmospheric CO<sub>2</sub> concentration

2018 ◽  
Vol 15 (21) ◽  
pp. 6559-6572 ◽  
Author(s):  
Xingjie Lu ◽  
Ying-Ping Wang ◽  
Yiqi Luo ◽  
Lifen Jiang
Keyword(s):  
Steady State ◽  
Transit Time ◽  
Climate Warming ◽  
Age Structure ◽  
C Sequestration ◽  
Turnover Time ◽  
Atmospheric Co2 ◽  
Ecosystem Carbon ◽  
Subsequent Decrease ◽  
Diagnostic Time

Abstract. Ecosystem carbon (C) transit time is a critical diagnostic parameter to characterize land C sequestration. This parameter has different variants in the literature, including a commonly used turnover time. However, we know little about how different transit time and turnover time are in representing carbon cycling through multiple compartments under a non-steady state. In this study, we estimate both C turnover time as defined by the conventional stock over flux and mean C transit time as defined by the mean age of C mass leaving the system. We incorporate them into the Community Atmosphere Biosphere Land Exchange (CABLE) model to estimate C turnover time and transit time in response to climate warming and rising atmospheric [CO2]. Modelling analysis shows that both C turnover time and transit time increase with climate warming but decrease with rising atmospheric [CO2]. Warming increases C turnover time by 2.4 years and transit time by 11.8 years in 2100 relative to that at steady state in 1901. During the same period, rising atmospheric [CO2] decreases C turnover time by 3.8 years and transit time by 5.5 years. Our analysis shows that 65 % of the increase in global mean C transit time with climate warming results from the depletion of fast-turnover C pool. The remaining 35 % increase results from accompanied changes in compartment C age structures. Similarly, the decrease in mean C transit time with rising atmospheric [CO2] results approximately equally from replenishment of C into fast-turnover C pool and subsequent decrease in compartment C age structure. Greatly different from the transit time, the turnover time, which does not account for changes in either C age structure or composition of respired C, underestimated impacts of warming and rising atmospheric [CO2] on C diagnostic time and potentially led to deviations in estimating land C sequestration in multi-compartmental ecosystems.

Study of Cells in the Steady-State Growth Space

2017 ◽  
pp. 233-258
Author(s):  
Sten Erm ◽  
Kristo Abner ◽  
Andrus Seiman ◽  
Kaarel Adamberg ◽  
Raivo Vilu
Keyword(s):  
Steady State ◽  
Steady State Growth ◽  
Growth Space ◽  
State Growth
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