scholarly journals Correlation between Oxygen Availability, Energy Charge, and Protein Synthesis in Squash Cotyledons Isolated from Germinating Seeds

1978 ◽  
Vol 61 (1) ◽  
pp. 85-88 ◽  
Author(s):  
Franca Rasi-Caldogno ◽  
Maria I. De Michelis
Keyword(s):  
Protein Synthesis ◽  
Energy Charge ◽  
Oxygen Availability ◽  
Germinating Seeds

Oxygen Availability as a Control Factor in the Density-Dependent Regulation of Protein Synthesis in Cell Culture

1974 ◽  
Vol 14 (2) ◽  
pp. 331-337
Author(s):  
DESH PAL S. VERMA ◽  
A. MARCUS
Keyword(s):  
Cell Culture ◽  
Protein Synthesis ◽  
Respiratory Rate ◽  
Initial Function ◽  
Fold Increase ◽  
Oxygen Availability ◽  
Control Factor ◽  
Atp Level ◽  
Density Dependent ◽  
Inadequate Nutrition

Dilution of a density-inhibited Arachis culture results in a 10-fold increase in capacity for protein synthesis during the first 2 h after dilution. The limitation in the density-inhibited state is not inadequate nutrition, inappropriate pH, or a diffusible inhibitor as the dilution can be carried out in medium obtained by filtration of 14-day cells. The respiratory rate of the culture increases 2-fold immediately after dilution and the ATP level increases 3-fold dunng the 2-h period subsequent to dilution. These observations suggest that the initial function activated by dilution is an increased availability of oxygen and that this increase in oxygen provides an increased level of ATP, finally resulting in an increased rate of protein synthesis. This idea is further supported by the finding that both the increase in cellular ATP and the acceleration of the rate of protein synthesis can be obtained in dense culture, in the absence of dilution, by maintaining the cells for 2 h under oxygen.

scholarly journals Oxygen and pH regulation of protein synthesis in mitochondria from Artemia franciscana embryos

1996 ◽  
Vol 313 (1) ◽  
pp. 207-213 ◽  
Author(s):  
Kurt E. KWAST ◽  
Steven C. HAND
Keyword(s):  
Protein Synthesis ◽  
Ph Regulation ◽  
Mitochondrial Protein ◽  
Oxygen Limitation ◽  
Oxygen Availability ◽  
Artemia Franciscana ◽  
Synthesis Rate ◽  
Protein Synthesis Rate ◽  
Mitochondrial Translation ◽  
Purine Nucleotides

To identify factors responsible for the down-regulation of mitochondrial biosynthetic processes during anoxia in encysted Artemia franciscana embryos, the effects of oxygen limitation and pH on protein synthesis were investigated in isolated mitochondria. At the optimal pH of 7.5, exposure of mitochondria to anoxia decreases the protein synthesis rate by 79%. Rates were suppressed by a further 10% at pH 6.8, the intracellular pH (pHi) measured under anoxia in vivo. Matrix pH, measured under identical conditions, was 8.43±0.01 at an extramitochondrial pH of 7.9 (mean±S.E.M., n = 3), 8.05±0.01 at pH 7.5, and 7.10±0.01 at pH 6.8. The matrix pH did not vary (P ≥0.20) as a function of oxygen availability during the 1 h assays. Intramitochondrial purine nucleotides varied little as a function of pH. In contrast, after 1 h of protein synthesis under anoxia, ATP levels decreased by up to 40%,. whereas AMP, ADP and GDP concentrations increased, and GTP and GMP concentrations remained relatively constant. The addition of 1 mM ATP at the onset of anoxia maintained the ATP/ADP ratio at the aerobic value, but did not stabilize the GTP/GDP ratio or rescue rates of protein synthesis. Thus, at present, we cannot eliminate the possibility that the decrease in the GTP/GDP ratio during anoxia may contribute to the suppression of protein synthesis. The effect of anoxia was reversible; the rate of protein synthesis upon reoxygenation after a 30 min bout of anoxia was comparable (P = 0.14) with the pre-anoxic rate (193±17 and 174±6 pmol of leucine per mg of protein respectively; mean±S.E.M., n = 3). The array of mitochondrial translation products did not differ qualitatively as a function of either oxygen availability or pH. Finally, similar pH profiles for protein synthesis were obtained with either [3H]leucine or [3H]histidine (known to use different transporters). Consequently, it is improbable that the pH-sensitivity of protein synthesis can be explained by a specific protein effect on the import of the radiolabelled amino acid used. In summary, both oxygen limitation and acidic pH suppress rates of mitochondrial protein synthesis and are likely to contribute to the arrest of mitochondrial anabolic processes during anoxia-induced quiescence in A. franciscana embryos.

scholarly journals Involvement of HSP Synthesis and Protease Inhibitors in Heat Shock-induced Cucumber Seedling Chilling Tolerance

HortScience ◽  
1995 ◽  
Vol 30 (4) ◽  
pp. 775F-775
Author(s):  
Paul H. Jennings ◽  
Ann Fitzpatrick
Keyword(s):  
Protein Synthesis ◽  
Heat Shock ◽  
Protease Inhibitors ◽  
Actinomycin D ◽  
Chilling Tolerance ◽  
Cucumber Seedling ◽  
Shock Effect ◽  
Seedling Roots ◽  
Germinating Seeds ◽  
Heat Shock Induction

Heat shock induction of chilling tolerance in cucumber seedlings is not blocked by inhibitors of protein synthesis. Treatment of germinating seeds with cycloheximide and actinomycin-D, prior to heat shock and chilling, does not block the heat shock induction of chilling tolerance, while the inhibitors alone promote chilling tolerance of seedling roots. To test whether the heat shock effect might be acting on proteases, two protease inhibitors (bestatin and PMSF) were tested for their ability to induce chilling tolerance. Although PMSF slowed germination, it still provided protection against chilling, but bestatin was much more effective.

Aortic perfusion pressure as a determinant of cardiac protein synthesis

1984 ◽  
Vol 246 (3) ◽  
pp. C247-C258 ◽  
Author(s):  
Y. Kira ◽  
P. J. Kochel ◽  
E. E. Gordon ◽  
H. E. Morgan
Keyword(s):  
Protein Synthesis ◽  
Oxygen Consumption ◽  
Perfusion Pressure ◽  
Energy Charge ◽  
Creatine Phosphate ◽  
Aortic Pressure ◽  
Cardiac Contraction ◽  
Adenylate Energy Charge ◽  
Rat Hearts ◽  
Pressure Development

Mechanical parameters and intracellular mediators that may control protein synthesis have been studied in isolated rat hearts subjected to increased aortic pressure or induced to perform cardiac work. Elevation of aortic pressure from 60 to 120 mmHg in Langendorff preparations with glucose, glucose plus insulin, or pyruvate raised the rate of protein synthesis during the 2nd h of perfusion. These effects involved faster rates of both peptide chain initiation and elongation. In working hearts supplied glucose or glucose plus insulin, higher rate of synthesis were observed in both the 1st and 2nd h of perfusion, compared with Langendorff preparations perfused at 60 mmHg. Intracellular levels of glucose 6-phosphate, ATP/ADP ratio, adenylate energy charge, or creatine phosphate/creatine did not correlate with the rate of protein synthesis in beating control hearts. When ventricular pressure development was prevented by ventricular draining and hearts were arrested with tetrodotoxin, protein synthesis still increased as a function of perfusion pressure. Oxygen consumption increased as aortic pressure was raised in beating-drained hearts but was unaffected in arrested-drained hearts. These results indicate that intraventricular pressure development, cardiac contraction, oxygen consumption, glucose 6-phosphate, energy availability, and coronary flow could be dissociated from the stimulatory effect of higher aortic pressures on protein synthesis and suggested that stretch of the ventricular wall, as a consequence of increased aortic pressure, could be the mechanical parameter most closely related to the increase in protein synthesis.

Ovine fetal leucine kinetics and protein metabolism during decreased oxygen availability

1998 ◽  
Vol 274 (4) ◽  
pp. E618-E626 ◽  
Author(s):  
J. Ross Milley
Keyword(s):  
Protein Synthesis ◽  
Oxygen Consumption ◽  
Fetal Growth ◽  
Oxygen Availability ◽  
Energy Needs ◽  
Leucine Kinetics ◽  
Metabolic Costs ◽  
Pool Model ◽  
Ovine Fetal ◽  
Maternal Hypoxia

The fetus depends on an uninterrupted supply of oxygen to provide energy, not only for basal metabolism but also for the metabolic costs of growth. By curtailing the metabolically expensive processes of protein turnover, the fetus could conserve energy when oxygen availability is limited. Therefore, this investigation was performed to find whether protein synthesis and breakdown are diminished during decreased fetal oxygen availability. Furthermore, if these conditions reduce fetal growth, protein synthesis should be affected more than breakdown so that protein accretion, an important component of fetal growth, also falls. In eight chronically prepared fetal lambs, we compared leucine kinetics (reciprocal pool model) during control conditions with measurements made during maternal hypoxia, a condition that limits fetal oxygen availability. Decreased fetal oxygen availability (−43%; P < 0.001) reduced fetal oxygen consumption (−16%; P < 0.01), as well as both the uptake of leucine across the placenta (−48%; P < 0.001) and its rate of decarboxylation (−30%; P < 0.001). Fetal protein synthesis decreased (−32%; P < 0.001) to a greater extent than proteolysis (−22%; P < 0.001). Consequently, fetal protein accretion, an important component of fetal growth, also decreased (−62%; P < 0.001). We calculate that the reduction in fetal protein synthesis and breakdown, both processes that require intracellular expenditure of ATP, decreased fetal energy needs sufficiently to account for most, if not all, of the decrease measured in fetal oxygen consumption.

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.

Sign in / Sign up

Export Citation Format

Share Document