Permeance to oxygen of detached Capsicum annuum fruit

2000 ◽  
Vol 40 (3) ◽  
pp. 457 ◽  
Author(s):  
J. Bower ◽  
B. D. Patterson ◽  
J. J. Jobling
Keyword(s):  
Oxygen Consumption ◽  
Gas Exchange ◽  
Capsicum Annuum ◽  
Oxygen Concentration ◽  
Concentration Gradient ◽  
Gas Diffusion ◽  
Major Barrier ◽  
Capsicum Annuum L ◽  
Rate Of Oxygen Consumption ◽  
Low Rate

The internal oxygen concentration and rate of oxygen consumption of detached capsicum fruits (Capsicum annuum L.) were monitored over several days. From this their overall permeance to oxygen was calculated. When wax was applied to the pedicel and its scar, permeance was reduced by 80–90%, indicating that most gas exchange occurred through this area. Readings from O2 sensors attached to the skins of the fruits were compared to those from O2 sensors inserted into the fruit cavity. These indicated that the cuticle was the major barrier to gas diffusion and that there was a concentration gradient through the capsicum flesh. Permeance of the cuticle was found to be about 0.64 x 10–4 mol O2/Pa.m2.s, while permeance to CO2 was 2–3 times higher. This suggests that the cuticle is composed of a coherent film. The low rate of gas diffusion through capsicum cuticle may allow recycling of respired CO2 by photosynthesis in the flesh before harvest.

Influence of Phosphorus and Endomycorrhiza (Glomus Intraradices) on gas exchange and plant growth of Chile Ancho Pepper (Capsicum Annuum L. cv. San Luis)

1999 ◽  
Vol 36 (3) ◽  
pp. 441-449 ◽  
Author(s):  
L. Aguilera-Gomez ◽  
F.T. Davies ◽  
V. Olalde-Portugal ◽  
S.A. Duray ◽  
L. Phavaphutanon
Keyword(s):  
Gas Exchange ◽  
Plant Growth ◽  
Capsicum Annuum ◽  
Glomus Intraradices ◽  
Capsicum Annuum L ◽  
San Luis

scholarly journals THE RESPIRATION OF LUMINOUS BACTERIA AND THE EFFECT OF OXYGEN TENSION UPON OXYGEN CONSUMPTION

1929 ◽  
Vol 13 (1) ◽  
pp. 27-45 ◽  
Author(s):  
Charles S. Shoup
Keyword(s):  
Carbon Dioxide ◽  
Oxygen Consumption ◽  
Oxygen Concentration ◽  
Oxygen Tension ◽  
Small Cells ◽  
Pure Oxygen ◽  
Catalytic Surfaces ◽  
Rate Of Oxygen Consumption ◽  
Luminous Bacteria ◽  
Effect Of Oxygen

1. The respiration of luminous bacteria has been studied by colorimetric and manometric methods. 2. Limulus oxyhaemocyanin has been used as a colorimetric indicator of oxygen consumption and indicator dyes were used for colorimetric determination of carbon dioxide production. 3. The Thunberg-Winterstein microrespirometer has been used for the measurement of the rate of oxygen consumption by luminous bacteria at different partial pressures of oxygen. 4. The effect of oxygen concentration upon oxygen consumption has been followed from equilibrium with air to low pressures of oxygen. 5. Luminous bacteria consume oxygen and produce carbon dioxide independent of oxygen pressures from equilibrium with air (152 mm.) to approximately 22.80 mm. oxygen or 0.03 atmosphere. 6. Dimming of a suspension of luminous bacteria occurs when oxygen tension is lowered to approximately 2 mm. Hg (0.0026 atmosphere) and when the rate of respiration becomes diminished one-half. 7. Pure nitrogen stops respiratory activity and pure oxygen irreversibly inhibits oxygen consumption. 8. The curve for rate of oxygen consumption with oxygen concentration is similar to curves for adsorption of gasses at catalytic surfaces, and agrees with the Langmuir equation for the expression of the amount of gas adsorbed in unimolecular layer at catalytic surfaces with gas pressure. 9. A constant and maximum rate of oxygen consumption occurs in small cells when oxygen concentration becomes sufficient to entirely saturate the surface of the oxidative catalyst of the cell.

AN IMPROVED MODEL FOR THE DIFFUSION OF OXYGEN INTO RESPIRING WOOD

2011 ◽  
Vol 19 (01) ◽  
pp. 101-112
Author(s):  
WERNER GEORG NOWAK ◽  
PETER HIETZ
Keyword(s):  
Oxygen Consumption ◽  
Oxygen Concentration ◽  
Tissue Level ◽  
State Equation ◽  
Gas Diffusion ◽  
Biological Processes ◽  
Tissue Oxygen ◽  
Improved Model ◽  
Exchange Surface ◽  
Tissue Oxygen Consumption

Diffusion is an essential component of gas exchange at the cellular and tissue level, and a mathematical analysis of diffusion is therefore important to model biological processes in many systems. When several factors affect diffusion, finding an explicit non-steady-state equation can be difficult or impossible. In an earlier work (J Biol Systems15:63–72), we described such a function for a system where oxygen diffuses from the air into a body that consumes oxygen, assuming that the exchange surface is flat. Here, an explicit solution is limited to the case where tissue oxygen consumption decreases linearly with oxygen concentration and reaches 0 only when all oxygen has been consumed. The objective of this article is the analysis of gas diffusion into a respiring tissue that is cylindrical, which applies to tree stems and is a more realistic approximation for many other organs. This approach differs from diffusion along a flat surface, resulting in formally completely different explicit solutions, and is more flexible allowing for different relationships between oxygen concentration and tissue oxygen consumption.

scholarly journals Functional conflicts between feeding and gas exchange in suspension-feeding tadpoles, Xenopus laevis

1984 ◽  
Vol 110 (1) ◽  
pp. 91-98 ◽  
Author(s):  
M. E. Feder ◽  
D. B. Seale ◽  
M. E. Boraas ◽  
R. J. Wassersug ◽  
A. G. Gibbs
Keyword(s):  
Oxygen Consumption ◽  
Gas Exchange ◽  
Xenopus Laevis ◽  
Suspension Feeding ◽  
Air Breathing ◽  
Aerial Respiration ◽  
Metabolic Requirement ◽  
Rate Of Oxygen Consumption ◽  
Food Particles ◽  
Hypoxic Water

Air-breathing tadpoles of Xenopus laevis (Amphibia: Anura) use buccopharyngeal surfaces for both gas exchange and capture of food particles in the water. In dense food suspensions, tadpoles decrease ventilation of the buccopharynx and increase air breathing. The lung ventilatory frequency is elevated even though the rate of oxygen consumption is at or below resting levels, suggesting that the lung hyperventilation reflects compensation for decreased buccopharyngeal respiration rather than an increased metabolic requirement. If tadpoles in hypoxic water are prevented from breathing air, they increase buccopharyngeal respiration at the expense of feeding. Aerial respiration evidently permits the buccopharyngeal surfaces to be used primarily for food entrapment.

Cardiac effects of hypoxia in the neotenous tiger salamanderAmbystoma tigrinum

2002 ◽  
Vol 205 (12) ◽  
pp. 1725-1734 ◽  
Author(s):  
Tom McKean ◽  
Guolian Li ◽  
Kong Wei
Keyword(s):  
Cardiac Output ◽  
Oxygen Consumption ◽  
Oxygen Concentration ◽  
Mechanical Performance ◽  
Cardiac Mass ◽  
Differentially Expressed ◽  
Representational Difference Analysis ◽  
Ambystoma Tigrinum ◽  
Rate Of Oxygen Consumption ◽  
Aquatic Salamanders

SUMMARYThe aquatic form of the tiger salamander Ambystoma tigrinum lives in high-altitude ponds and is exposed to a hypoxic environment that may be either chronic or intermittent. In many animal species, exposure to hypoxia stimulates cardiac output and is followed by an increase in cardiac mass. The working hypothesis of the present study was that the hearts of these aquatic salamanders exposed to 10-14 days of 5 % oxygen in a laboratory setting would become larger and would differentially express proteins that would help confer tolerance to hypoxia. During exposure to hypoxia, cardiac output increased, as did hematocrit. Cardiac mass also increased, but mitotic figures were not detected in the cardiac myocytes of colchicine-injected animals. The mass increase was probably due to hypertrophy, although a very slow rate of hyperplasia cannot be ruled out. Representational difference analysis indicated that at least 14 mRNAs were expressed in hearts from the hypoxic animals that were not expressed in hearts from normoxic animals. The differentially expressed genes were cloned and sequenced and confirmed as coming from the ventricles of the hypoxic salamanders. Genes differentially expressed include mitochondrial genes and genes for elongation factor 2, a protein synthesis gene. The mechanical performance of buffer-perfused hearts isolated from normoxic and hypoxic animals did not differ. Acute responses to hypoxia were also measured. The rate of oxygen consumption of unanesthetized salamanders in metabolism chambers decreased when chamber oxygen concentration was reduced below 12 % oxygen. At a chamber oxygen concentration of 4-6 %, the rate of oxygen consumption of the salamanders was reduced to approximately one-third of the normoxic rate.

THE POTASSIUM UPTAKE AND RATE OF OXYGEN CONSUMPTION OF ISOLATED FROG SKELETAL MUSCLE IN THE PRESENCE OF INSULIN AND LACTATE

1956 ◽  
Vol 34 (5) ◽  
pp. 893-902 ◽  
Author(s):  
J. F. Manery ◽  
D. R. H. Gourley ◽  
Kenneth C. Fisher
Keyword(s):  
Skeletal Muscle ◽  
Oxygen Consumption ◽  
Concentration Gradient ◽  
Skeletal Muscles ◽  
Potassium Uptake ◽  
Frog Skeletal Muscle ◽  
High Concentration ◽  
Ringer’S Solution ◽  
Rate Of Oxygen Consumption

Insulin (5.0 × 10−2 units per ml.) and lactate (5.0 × 10−3 M) caused an uptake of potassium by intact frog skeletal muscles in vitro, and a concomitant loss of potassium from the medium surrounding the muscles; this fluid was Ringer's solution containing 2.1 meq. of potassium per liter. Thus a movement of potassium against a high concentration gradient has been demonstrated. In general, the conditions under which potassium uptake occurred stimulated the oxygen consumption of the muscles. Monoiodoacetic acid (2.5 × 10−4 M) abolished the effect of insulin on the potassium uptake and greatly reduced its effect on the oxygen consumption.

Hovering Performance of Hummingbirds in Hyperoxic Gas Mixtures

2001 ◽  
Vol 204 (11) ◽  
pp. 2021-2027 ◽  
Author(s):  
Douglas L. Altshuler ◽  
Peng Chai ◽  
Jeff S. P. Chen
Keyword(s):  
Oxygen Consumption ◽  
Oxygen Concentration ◽  
Atmospheric Oxygen ◽  
Supplemental Oxygen ◽  
Hovering Flight ◽  
Density Reduction ◽  
Air Density ◽  
Reduction Experiment ◽  
Elevational Distribution ◽  
Rate Of Oxygen Consumption

SUMMARY Hummingbirds evolved during a period of decline in atmospheric oxygen concentration and currently encounter varying levels of oxygen availability along their elevational distribution. We tested the hypothesis that inspiration of hyperoxic gas increases hummingbird hovering performance when birds are simultaneously challenged aerodynamically. We measured the maximum duration of hovering flight while simultaneously monitoring the rate of oxygen consumption of ruby-throated hummingbirds (Archilochus colubris) in low-density heliox that was either normoxic (21% O2) or hyperoxic (35% O2). As air density decreased below 0.85kgm−3, hummingbirds hovered significantly longer in hyperoxia than in normoxia, but the air density at which the birds could no longer sustain hovering flight was independent of oxygen concentration. At low air densities in hyperoxia flight trials, hummingbirds appeared to increase their rate of oxygen consumption relative to flight sequences at equivalent densities in normoxia trials, but these differences were not significant. We tested the hypothesis that hummingbirds can discriminate between environments that differ in oxygen concentration. In another density-reduction experiment, hummingbirds were allowed to choose between artificial feeders infused with either normoxic or hyperoxic gases. The hypothesis was not supported because birds failed to associate oxygen concentration with a particular feeder independently of air density. Supplemental oxygen thus yields increased hovering duration at intermediate air densities, but the minimum density at which birds can fly is limited exclusively by aerodynamic considerations.

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