Gloxy: An oxygen-sensitive coal for accurate measurement of low oxygen tensions in biological systems

1997 ◽  
Vol 38 (1) ◽  
pp. 48-58 ◽  
Author(s):  
Philip E. James ◽  
Oleg Y. Grinberg ◽  
Fuminori Goda ◽  
Tomasz Panz ◽  
Julia A. O'Hara ◽  
...  
Keyword(s):  
Biological Systems ◽  
Low Oxygen ◽  
Oxygen Sensitive ◽  
Oxygen Tensions

Sensitivity of malaria parasites to nitric oxide at low oxygen tensions

The Lancet ◽  
1998 ◽  
Vol 351 (9116) ◽  
pp. 1630 ◽  
Author(s):  
AW Taylor-Robinson ◽  
M Looker
Keyword(s):  
Nitric Oxide ◽  
Low Oxygen ◽  
Malaria Parasites ◽  
Oxygen Tensions

scholarly journals Protein Import into Hydrogenosomes of Trichomonas vaginalis Involves both N-Terminal and Internal Targeting Signals: a Case Study of Thioredoxin Reductases

2008 ◽  
Vol 7 (10) ◽  
pp. 1750-1757 ◽  
Author(s):  
Marek Mentel ◽  
Verena Zimorski ◽  
Patrick Haferkamp ◽  
William Martin ◽  
Katrin Henze
Keyword(s):  
Trichomonas Vaginalis ◽  
Protein Import ◽  
Atp Synthesis ◽  
Antioxidant Systems ◽  
Low Oxygen ◽  
Oxygen Sensitive ◽  
Targeting Signal ◽  
Targeting Signals ◽  
Thioredoxin Reductases

ABSTRACT The parabasalian flagellate Trichomonas vaginalis harbors mitochondrion-related and H2-producing organelles of anaerobic ATP synthesis, called hydrogenosomes, which harbor oxygen-sensitive enzymes essential to its pyruvate metabolism. In the human urogenital tract, however, T. vaginalis is regularly exposed to low oxygen concentrations and therefore must possess antioxidant systems protecting the organellar environment against the detrimental effects of molecular oxygen and reactive oxygen species. We have identified two closely related hydrogenosomal thioredoxin reductases (TrxRs), the hitherto-missing component of a thioredoxin-linked hydrogenosomal antioxidant system. One of the two hydrogenosomal TrxR isoforms, TrxRh1, carried an N-terminal extension resembling known hydrogenosomal targeting signals. Expression of hemagglutinin-tagged TrxRh1 in transfected T. vaginalis cells revealed that its N-terminal extension was necessary to import the protein into the organelles. The second hydrogenosomal TrxR isoform, TrxRh2, had no N-terminal targeting signal but was nonetheless efficiently targeted to hydrogenosomes. N-terminal presequences from hydrogenosomal proteins with known processing sites, i.e., the alpha subunit of succinyl coenzyme A synthetase (SCSα) and pyruvate:ferredoxin oxidoreductase A, were investigated for their ability to direct mature TrxRh1 to hydrogenosomes. Neither presequence directed TrxRh1 to hydrogenosomes, indicating that neither extension is, by itself, sufficient for hydrogenosomal targeting. Moreover, SCSα lacking its N-terminal extension was efficiently imported into hydrogenosomes, indicating that this extension is not required for import of this major hydrogenosomal protein. The finding that some hydrogenosomal enzymes require N-terminal signals for import but that in others the N-terminal extension is not necessary for targeting indicates the presence of additional targeting signals within the mature subunits of several hydrogenosome-localized proteins.

scholarly journals Oxygen-sensitive stages of the cell cycle of human diploid cells.

1978 ◽  
Vol 78 (2) ◽  
pp. 390-400 ◽  
Author(s):  
A K Balin ◽  
D B Goodman ◽  
H Rasmussen ◽  
V J Cristofalo
Keyword(s):  
Cell Cycle ◽  
Dna Synthesis ◽  
Oxygen Tension ◽  
Cycle Growth ◽  
Partial Pressures ◽  
Oxygen Sensitive ◽  
Oxygen Tensions ◽  
Human Diploid Cells ◽  
Diploid Cells

We had established that growth of human diploid WI-38 cells is reversibly inhibited by elevated partial pressures of oxygen (PO2) and we were interested in determining where in the cell cycle growth was delayed. A technique combining cytospectrophotometry and autoradiography was used to determine cell cycle parameters. Confluent cells that were subcultivated and exposed to a PO2 of 365 +/- 8 mm Hg were delayed primarily after DNA synthesis but before metaphase. At a PO2 of 590 +/- 35 mm Hg, most cells did not initiate DNA synthesis, and the few that did, failed to complete the process. When exponentially growing cells that had already begun DNA synthesis were exposed to a PO2 of 590 p 35 mm Hg, they accumulated after completing DNA synthesis but before initiating mitosis. The rate at which (3H)thymidine was incorporated into DNA was inversely correlated with oxygen tension (PO2 of 135--590 mm Hg). These results suggest that the process most sensitive to oxygen causes cells to be delayed after DNA synthesis but before metaphase. Slightly higher PO2's were needed to inhibit the initiation of DNA synthesis. Further, the rate of DNA synthesis is decreased by elevated oxygen tensions.

scholarly journals The Steady-State Transport of Oxygen through Hemoglobin Solutions

1966 ◽  
Vol 49 (4) ◽  
pp. 663-679 ◽  
Author(s):  
K. H. Keller ◽  
S. K. Friedlander
Keyword(s):  
Diffusion Coefficient ◽  
Brownian Motion ◽  
Steady State ◽  
Effective Diffusion ◽  
Close Correlation ◽  
Oxygen Electrode ◽  
Low Oxygen ◽  
Diffusion Rates ◽  
Oxygen Tensions ◽  
Diffusion Coefficient Of Oxygen

The steady-state transport of oxygen through hemoglobin solutions was studied to identify the mechanism of the diffusion augmentation observed at low oxygen tensions. A novel technique employing a platinum-silver oxygen electrode was developed to measure the effective diffusion coefficient of oxygen in steady-state transport. The measurements were made over a wider range of hemoglobin and oxygen concentrations than previously reported. Values of the Brownian motion diffusion coefficient of oxygen in hemoglobin solution were obtained as well as measurements of facilitated transport at low oxygen tensions. Transport rates up to ten times greater than ordinary diffusion rates were found. Predictions of oxygen flux were made assuming that the oxyhemoglobin transport coefficient was equal to the Brownian motion diffusivity which was measured in a separate set of experiments. The close correlation between prediction and experiment indicates that the diffusion of oxyhemoglobin is the mechanism by which steady-state oxygen transport is facilitated.

scholarly journals MNRR1, a Biorganellar Regulator of Mitochondria

2017 ◽  
Vol 2017 ◽  
pp. 1-12 ◽  
Author(s):  
Lawrence I. Grossman ◽  
Neeraja Purandare ◽  
Rooshan Arshad ◽  
Stephanie Gladyck ◽  
Mallika Somayajulu ◽  
...  
Keyword(s):  
Energy Metabolism ◽  
Neurodegenerative Diseases ◽  
Family Members ◽  
Unusual Property ◽  
Promoter Element ◽  
Low Oxygen ◽  
Oxidative Stresses ◽  
Graded Response ◽  
Oxygen Tensions

The central role of energy metabolism in cellular activities is becoming widely recognized. However, there are many gaps in our knowledge of the mechanisms by which mitochondria evaluate their status and call upon the nucleus to make adjustments. Recently, a protein family consisting of twin CX9C proteins has been shown to play a role in human pathophysiology. We focus here on two family members, the isoforms CHCHD2 (renamed MNRR1) and CHCHD10. The better studied isoform, MNRR1, has the unusual property of functioning in both the mitochondria and the nucleus and of having a different function in each. In the mitochondria, it functions by binding to cytochromecoxidase (COX), which stimulates respiration. Its binding to COX is promoted by tyrosine-99 phosphorylation, carried out by ABL2 kinase (ARG). In the nucleus, MNRR1 binds to a novel promoter element inCOX4I2and itself, increasing transcription at 4% oxygen. We discuss mutations in both MNRR1 and CHCHD10 found in a number of chronic, mostly neurodegenerative, diseases. Finally, we propose a model of a graded response to hypoxic and oxidative stresses, mediated under different oxygen tensions by CHCHD10, MNRR1, and HIF1, which operate at intermediate and very low oxygen concentrations, respectively.

Survival in Hostile Environments: Strategies of Renal Medullary Cells

Physiology ◽  
2006 ◽  
Vol 21 (3) ◽  
pp. 171-180 ◽  
Author(s):  
Wolfgang Neuhofer ◽  
Franz-X. Beck
Keyword(s):  
Reactive Oxygen Species ◽  
Reactive Oxygen ◽  
Renal Medulla ◽  
Extreme Conditions ◽  
Oxygen Species ◽  
Low Oxygen ◽  
Oxygen Tensions ◽  
Hostile Environments ◽  
Medullary Cells

Cells in the renal medulla exist in a hostile milieu characterized by wide variations in extracellular solute concentrations, low oxygen tensions, and abundant reactive oxygen species. This article reviews the strategies adopted by these cells to allow them to survive and fulfill their functions under these extreme conditions.

CIRCULATORY RESPONSES TO LOW OXYGEN TENSIONS

1919 ◽  
Vol 50 (2) ◽  
pp. 228-251 ◽  
Author(s):  
Brenton R. Lutz ◽  
Edward C. Schneider
Keyword(s):  
Low Oxygen ◽  
Oxygen Tensions
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