scholarly journals 407 Regulation of Carbon Flux as a Function of O2 and CO2 Atmospheres in Asparagus Tips

HortScience ◽  
1999 ◽  
Vol 34 (3) ◽  
pp. 514B-514
Author(s):  
S.M. Silva ◽  
R.C. Herner ◽  
R.M. Beaudry
Keyword(s):  
Oxidative Phosphorylation ◽  
Partial Pressure ◽  
Surface Area ◽  
Carbon Metabolism ◽  
Carbon Flux ◽  
Energy Charge ◽  
Low Density Polyethylene ◽  
Low Density ◽  
Adenylate Energy Charge ◽  
Partial Pressures

The purpose of this work was to investigate the influence of O2 and CO2 partial pressures on glycolytic carbon flux, phosphorylated intermediates, phosphate, pyrophosphate, and phosporylated nucleotides in asparagus spears tips stores at 1 °C. The effects of CO2 (0, 5, 10, and 20 kPa) combined with O2 pressures ranging from 0.1 to 16 kPa (1% O2 = 1.013 kPa O2 at 1 atm) were investigated. Spears were enclosed within a low-density polyethylene (LDPE) package (for the 5-, 10-, and 20-kPa CO2 treatments) having a surface area of 462 cm2 and enclosed in 1.95-L glass jars. Low O2 enhanced the interconversion of phosphoenolpyruvate (PEP) to pyruvate (PYR) and F6P to F1,6P2 relative to high O2. When spears tips at 16 kPa O2 were compared to those at harvest, little change occurred in the adenylate or phosphate pools. PPi and ATP contents decreased as the O2 partial pressure declined below 16 kPa O2. In general, as CO2 increased, PPi and ATP decreased, while Pi, ADP, and AMP increased. The adenylate energy charge (AEC) declined with a decline in the O2 partial pressure, declining most rapidly below 2 kPa O2. Low O2 reduced AEC relative to high O2. Increasing CO2 partial pressure reduced AEC, an effect not evident at lower O2. The data suggest low O2 and elevated CO2 impair oxidative phosphorylation and induce nonsustaining carbon metabolism, which may limit asparagus spear survival under O2-deficient conditions.

Effect of cyclosporine on oxidative phosphorylation and adenylate energy charge of regenerating rat liver

1989 ◽  
Vol 189 (5) ◽  
pp. 313-320 ◽  
Author(s):  
S. Uemoto ◽  
K. Tanaka ◽  
K. Asonuma ◽  
R. Okamura ◽  
Y. Kitakado ◽  
...  
Keyword(s):  
Oxidative Phosphorylation ◽  
Rat Liver ◽  
Energy Charge ◽  
Adenylate Energy Charge ◽  
Regenerating Rat Liver

scholarly journals Germination, Respiration, and Adenylate Energy Charge of Seeds at Various Oxygen Partial Pressures

1985 ◽  
Vol 79 (3) ◽  
pp. 885-890 ◽  
Author(s):  
Ali Al-Ani ◽  
Françoise Bruzau ◽  
Philippe Raymond ◽  
Véronique Saint-Ges ◽  
Jean Marc Leblanc ◽  
...  
Keyword(s):  
Energy Charge ◽  
Adenylate Energy Charge ◽  
Partial Pressures

scholarly journals Morphological modification of low-density polyethylene for enhanced Phanerochaete chrysosporium surface bioerosion

2021 ◽  
Author(s):  
Shloka V. Janapaty
Keyword(s):  
Surface Area ◽  
Phanerochaete Chrysosporium ◽  
Conformational Changes ◽  
Chemical Etching ◽  
Polymer Surface ◽  
Low Density Polyethylene ◽  
Low Density ◽  
Area Reduction ◽  
Synthetic Leachate ◽  
Surface Area Reduction

Disposal of end-of-life low density polyethylene (LDPE) in landfill structures poses an ecological threat through leaching, fragmentation, and additive migration. The present study examines the mycodegradation of morphologically modified low- density polyethylene (LDPE) films by Phanerochaete chrysosporium, a lignolytic basidiomycete. Three physicochemical treatments were employed: thermo-oxidation, chemical etching, and synthetic leachate. Surface area imaging over 6 days revealed bioerosion, qualifying P. chrysosporium as a suitable agent for LDPE degradation. Analysis of crystallinity indices showed that thermo-oxidation and chemical etching induced conformational changes to the polymer surface, increasing surface area reduction by 19% and 22% respectively. Synthetic leachate (SL) was associated with a 36% increase in surface area reduction. In combination, the three treatments achieved a 99% increase in surface area reduction. These trends were corroborated by gaseous evolution in parallel, attributable to the metabolization of fungal isolates. Electrospray Ionization Fourier Transform (FTMS + pESI) profiles observed signs of leachate remediation and organic byproducts. A molecular mechanism for degradation was subsequently proposed based on SL composition.

Effect of 5-nitroindole on adenylate energy charge, oxidative phosphorylation, and lipid peroxidation in rat hepatocytes

1994 ◽  
Vol 48 (7) ◽  
pp. 1483-1492 ◽  
Author(s):  
Marta Dubin ◽  
Patricia H. Carrizo ◽  
Ana M. Biscardi ◽  
Silvia H. Fernandez Villamil ◽  
Andrés O.M. Stoppani
Keyword(s):  
Lipid Peroxidation ◽  
Oxidative Phosphorylation ◽  
Energy Charge ◽  
Rat Hepatocytes ◽  
Adenylate Energy Charge

scholarly journals Relationship Between Protein Synthesis and Secretion in Liver Cells and the State of the Adenine Nucleotide System

1979 ◽  
Vol 32 (3) ◽  
pp. 299 ◽  
Author(s):  
Kaylene Edwards ◽  
Jörg Urban ◽  
Gerhard Schreiber
Keyword(s):  
Protein Synthesis ◽  
Oxidative Phosphorylation ◽  
Protein Secretion ◽  
Liver Cell ◽  
Maximum Rate ◽  
Adenine Nucleotide ◽  
Energy Charge ◽  
Adenylate Energy Charge ◽  
Atp Level ◽  
Atp Pool

Adenine nucleotide levels could be precisely and reproducibly adjusted in liver cell suspensions by partially depleting the ATP pool with D-fructose or glycerol. Thus, it was possible to quantitatively correlate rates of protein synthesis and secretion with intracellular levels of ATP and with derived parameters, such as the adenylate energy charge. Half the maximum rate of incorporation of leucine into protein was observed at an energy charge of 0�80, a ratio of ATP to ADP of 2�6, and an ATP level of 1�05 pmol per g of wet cells. Proteins were secreted with half the maximum rate at an energy charge of 0�85, a ratio of ATP to ADP of 3�1 and an ATP concentration of 1 �1 pmol per gof wet cells. Protein secretion dill not depend on continued synthesis. Inhibitors of oxidative phosphorylation inhibited protein secretion in addition to protein synthesis, in contrast to observations by other authors on liver slices.

scholarly journals Modified-atmosphere Packaging of `Heritage' Red Raspberry Fruit: Respiratory Response to Reduced Oxygen, Enhanced Carbon Dioxide, and Temperature

1994 ◽  
Vol 119 (3) ◽  
pp. 540-545 ◽  
Author(s):  
Dennis W. Joles ◽  
Arthur C. Cameron ◽  
Ahmad Shirazi ◽  
Peter D. Petracek ◽  
Randolph M. Beaudry
Keyword(s):  
Steady State ◽  
Film Thickness ◽  
Partial Pressure ◽  
Surface Area ◽  
Modified Atmosphere Packaging ◽  
Fruit Weight ◽  
Rubus Idaeus ◽  
Modified Atmosphere ◽  
Modified Atmospheres ◽  
Partial Pressures

`Heritage' raspberries (Rubus idaeus L.) were sealed in low-density polyethylene packages and stored at 0, 10, and 20C during Fall 1990 and 1991 to study respiratory responses under modified atmospheres. A range of steady-state O2 and CO2 partial pressures were achieved by varying fruit weight in packages of a specific surface area and film thickness. Film permeability to O2 and CO2 was measured and combined with surface area and film thickness to estimate total package permeability. Rates of O2 uptake and CO2 production and respiratory quotient (RQ) were calculated using steady-state O2 and CO2 partial pressures, total package permeability, and fruit weight. The O2 uptake rate decreased with decreasing O2 partial pressure over the range of partial pressure studied. The Michaelis-Menten equation was used to model O2 uptake as a function of O2 partial pressure and temperature. The apparent Km(K½) remained constant (5.6 kPa O2 with temperature, while Q10 was estimated to be 1.9. RQ was modeled as a function of O2 partial pressure and temperature. Headspace ethanol increased at RQs >1.3 to 1.5. Based on RQ, ethanol production, and flavor, we recommend that raspberries be stored at O2 levels above 4 kPa at 0C, 6 kPa at 10C, and 8 kPa at 20C. Steady-state CO2 partial pressures of 3 to 17 kPa had little or no effect on O2 uptake or headspace ethanol partial pressures at 20C.

scholarly journals DETERMINATION OF LOW OXYGEN TOLERANCE LIMITS FOR SEVERAL APPLE CULTIVARS

HortScience ◽  
1992 ◽  
Vol 27 (6) ◽  
pp. 592g-593
Author(s):  
Christopher D. Gran ◽  
Randolph M. Beaudry
Keyword(s):  
Steady State ◽  
Anaerobic Respiration ◽  
Low Density Polyethylene ◽  
Low Density ◽  
Low Oxygen ◽  
Tolerance Limits ◽  
Partial Pressures ◽  
Lower Oxygen ◽  
Apple Cultivars

The oxygen partial pressure associated with the respiratory quotient (RQ) breakpoint (ie., lower oxygen limit) was determined for fruits of several apple cultivars stored at 0°C. Fruits were sealed in low density polyethylene pouches of various thicknesses and known permeability to determine O2 uptake, CO2 production, and respiratory quotients (RQ) at various O2 partial pressures. There were differences in the shape of O2 uptake versus steady state O2 curves between cultivars. While some cultivars showed steady declines in respiration rate from 8 kPa O2 to < 1 kPa, other cultivars showed no decline in respiration until O2 levels fell below 3 to 4 kPa. Fruits having elevated RQ values had greater levels of headspace ethanol in the polyethylene pouches, which confirmed anaerobic respiration. The lower oxygen limit ranged from a low of approximately 0.75 kPa for cultivars Northern Spy and Law Rome to high of 1.5 kPa for McIntosh.

Differential Contribution of Oxidative and Glycolytic Energy to Thrombin-Induced Platelet Functions

1979 ◽  
Vol 42 (02) ◽  
pp. 655-665 ◽  
Author(s):  
Bonro Kobayashi ◽  
Yasuko Watanabe ◽  
Naoyuki Takasugi ◽  
Makiko Kurita
Keyword(s):  
Oxidative Phosphorylation ◽  
Blood Platelets ◽  
Energy Charge ◽  
Krebs Cycle ◽  
Energy Condition ◽  
Pulse Labelling ◽  
Adenylate Energy Charge ◽  
Comparable Amount ◽  
Respiratory Inhibitors ◽  
Platelet Aggregates

SummaryWhen washed rabbit-blood platelets were preincubated in an artificial medium in the absence of external substrates, they aggregated in response to a low concentration of thrombin. The aggregation was completely inhibited after the preincubation with respiratory inhibitors. When glucose together with the respiratory inhibitors was added during the incubation, the aggregation was accelerated, whilst it was counteracted when Krebs-cycle substrates were added.ATP was generated actively during the incubation in the absence of external substrates, as well as in the presence of succinate. The ATP-generation was extremely inhibited by oligomycin. When glucose was added during the incubation with the respiratory inhibitor, the comparable amount of ATP with those in the oxidative systems was generated. Metabolic ADP was accumulated in the oxidative systems, particularly in the presence of succinate, in contrast to its low level in the glucose + oligomycin system. The results suggest that the counteraction of the aggregation by the Krebs-cycle substrate is attributed to the low adenylate energy charge. It is suggested that anaerobic glycolysis creates favorable energy condition for aggregation as compared with oxidative phosphorylation, although the washed platelets can be energized to a level above threshold of the aggregation when either one of the two energy generating systems is exerted.After the incubation of the platelets in the presence of thrombin, a higher level of metabolic ATP was observed under glycolytic condition, than under oxidative condition. Pulse-labelling experiments showed that ADP produced during the aggregation was rephosphorylated in a later part of the incubation in the glucose + KCN-fortified system. In the succinate-fortified system, the re-phosphorylation was very slow. The results suggest that oxidative phosphorylation is reduced in platelet aggregates treated with thrombin.

scholarly journals Lethality caused by ADP-glucose accumulation is suppressed by salt-induced carbon flux redirection in cyanobacteria

2019 ◽  
Vol 71 (6) ◽  
pp. 2005-2017
Author(s):  
Sandra Díaz-Troya ◽  
Miguel Roldán ◽  
Manuel J Mallén-Ponce ◽  
Pablo Ortega-Martínez ◽  
Francisco J Florencio
Keyword(s):  
Carbon Flux ◽  
Glycogen Synthase ◽  
Adenine Nucleotide ◽  
Energy Charge ◽  
Adenylate Energy Charge ◽  
Nitrogen Deprivation ◽  
Lethal Phenotype ◽  
Photosynthetic Organisms ◽  
Glucose Synthesis ◽  
Glucose Accumulation

Abstract Cyanobacteria are widely distributed photosynthetic organisms. During the day they store carbon, mainly as glycogen, to provide the energy and carbon source they require for maintenance during the night. Here, we generate a mutant strain of the freshwater cyanobacterium Synechocystis sp. PCC 6803 lacking both glycogen synthases. This mutant has a lethal phenotype due to massive accumulation of ADP-glucose, the substrate of glycogen synthases. This accumulation leads to alterations in its photosynthetic capacity and a dramatic decrease in the adenylate energy charge of the cell to values as low as 0.1. Lack of ADP-glucose pyrophosphorylase, the enzyme responsible for ADP-glucose synthesis, or reintroduction of any of the glycogen synthases abolishes the lethal phenotype. Viability of the glycogen synthase mutant is also fully recovered in NaCl-supplemented medium, which redirects the surplus of ADP-glucose to synthesize the osmolite glucosylglycerol. This alternative metabolic sink also suppresses phenotypes associated with the defective response to nitrogen deprivation characteristic of glycogen-less mutants, restoring the capacity to degrade phycobiliproteins. Thus, our system is an excellent example of how inadequate management of the adenine nucleotide pools results in a lethal phenotype, and the influence of metabolic carbon flux in cell viability and fitness.

scholarly journals Boron Nitride-Filled Linear Low-Density Polyethylene for Enhanced Thermal Transport: Continuous Extrusion of Micro-Textured Films

Polymers ◽  
2021 ◽  
Vol 13 (19) ◽  
pp. 3393
Author(s):  
Özgün Güzdemir ◽  
Sagar Kanhere ◽  
Victor Bermudez ◽  
Amod A. Ogale
Keyword(s):  
Thermal Conductivity ◽  
Boron Nitride ◽  
Surface Area ◽  
Thermal Transport ◽  
Polymer Materials ◽  
Low Density Polyethylene ◽  
Packaging Materials ◽  
Low Density ◽  
Linear Low Density Polyethylene ◽  
Continuous Extrusion

With shrinking size of electronic devices, increasing performance and accompanying heat dissipation, there is a need for efficient removal of this heat through packaging materials. Polymer materials are attractive packaging materials given their low density and electrical insulating properties, but they lack sufficient thermal conductivity that inhibits heat transfer rate. Hexagonal boron nitride (BN) possesses excellent thermal conductivity and is also electrically insulating, therefore BN-filled polymer composites were investigated in this study. Results showed successful continuous extrusion of BN-filled linear low-density polyethylene through micro-textured dies that is a scalable manufacturing process. Through-thickness thermal conductivity measurements established that 30 vol% BN content led to an over 500% increase in thermal conductivity over that of pure polymer. Textured film surface provided about a 50% increase in surface area when compared with non-textured films. This combination of increased surface area and enhanced thermal conductivity of BN-filled textured films indicates their potential application for improved convective thermal transport.

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