The Function of Haemoglobin in Relation to the Maintenance of Neutral Buoyancy in Anisops Pellucens (Notonectidae, Hemiptera)

1966 ◽  
Vol 44 (3) ◽  
pp. 529-543 ◽  
Author(s):  
P. L. MILLER
Keyword(s):  
Temperature Sensitive ◽  
Gas Migration ◽  
Neutral Buoyancy ◽  
Tracheal System ◽  
Percentage Saturation ◽  
Ambient Oxygen ◽  
Normal Duration ◽  
Oxygen Tensions ◽  
Normal Respiration ◽  
Physical Gill

1. The percentage saturation of the haemoglobin of the intact water bug, Anisops pellucens, in equilibrium with various ambient oxygen tensions has been determined. From this an approximate dissociation curve for the pigment and a P50 value of 28 mm. Hg at 24° C. have been obtained. 2. Anisaps haemoglobmn shows no Bohr effect, but appears to be very temperature-sensitive. 3. During free dives the haemoglobmn is regularly de-oxygenated; the oxygen so derived probably helps to maintain the bug in neutral buoyancy for much of each dive. 4. Carbon monoxide has been used to inactivate the haemoglobin, after which dives are reduced to about one-fifth of their normal duration and the phase of neutral buoyancy is abolished. 5. Much of the oxygen which leaves the pigment probably diffuses into the ventral airstore and then re-enters the tracheal system via the thoracic spiracles. External ‘pumping’ movements may serve to speed this gas migration. It is argued that physical gill action plays a negligible part in the normal respiration of this species.

Influence of some factors on oxygen uptake of canine cardiac Purkinje fibers

1963 ◽  
Vol 204 (1) ◽  
pp. 5-8 ◽  
Author(s):  
Kalman Greenspan ◽  
Paul F. Cranefield
Keyword(s):  
Oxygen Uptake ◽  
Oxygen Concentration ◽  
Diffusion Limitation ◽  
Purkinje Fibers ◽  
Ambient Oxygen ◽  
Cardiac Purkinje Fibers ◽  
Lower Oxygen ◽  
Wet Weight ◽  
Oxygen Tensions ◽  
Oxygen Concentrations

The rate of oxygen uptake of quiescent Purkinje fibers of the dog's heart was determined using a flow respirometer and oxygen polarography. At ambient oxygen concentrations of 60% or higher the rate of uptake was 0.739 mm3/mg wet weight per hr at 35 C. The temperature coefficient over the range 25–35° was 2.3. The uptake was independent of the ambient oxygen concentration at oxygen concentrations equal to or greater than 60% of an atmosphere. In lower oxygen concentrations the rate of uptake was found to be depressed. The depression of uptake in the lower oxygen tensions is probably the result of diffusion limitation; it may, however, reflect dependence of resting uptake on oxygen concentration.

scholarly journals The effect of oxygen and vitamin E on the lifespan of human diploid cells in vitro.

1977 ◽  
Vol 74 (1) ◽  
pp. 58-67 ◽  
Author(s):  
A K Balin ◽  
D B Goodman ◽  
H Rasmussen ◽  
V J Cristofalo
Keyword(s):  
Oxygen Toxicity ◽  
Alpha Tocopherol ◽  
Ambient Oxygen ◽  
Oxygen Tensions ◽  
Effect Of Oxygen ◽  
Population Doublings ◽  
Human Diploid Cells ◽  
Diploid Cells ◽  
Phase Out

Human diploid cells (WI-38) were serially subcultivated at partial pressures of oxygen (Po2) ranging from 5.6 mm Hg to 608 mm Hg. At a Po2 of 5.6 mm Hg, the number of doublings to phase out was less than that of control cells at a Po2 of 137 mm Hg. Cultures grown at Po2's of 24, 49, or 137 mm Hg grew at the same rate and phased out after a similar number of population doublings. Population lifespan was markedly shortened by chronic exposure to elevated Po2's, a phenomenon that was, in part, reversible. d-1-alpha-Tocopherol (10 microgram/ml or 100 microgram/ml) homogenized into the medium at each weekly subcultivation did not extend the lifespan of cells at reduced, ambient, or elevated oxygen tensions. These results indicate that neither oxygen toxicity nor free radical reactions play a significant role in limiting the lifespan of WI-38 cells grown in vitro under ambient oxygen tensions (Po2 137 mm Hg).

Oxygen-sensitive flight metabolism in the dragonfly erythemis simplicicollis

1998 ◽  
Vol 201 (11) ◽  
pp. 1739-1744 ◽  
Author(s):  
JF Harrison ◽  
JR Lighton
Keyword(s):  
Insect Flight ◽  
Atmospheric Oxygen ◽  
Safety Margin ◽  
Oxygen Level ◽  
Tracheal System ◽  
Muscle Oxygen ◽  
Ambient Oxygen ◽  
Resting Metabolism ◽  
Oxygen Sensitive ◽  
Flight Metabolism

Insect flight metabolism is completely aerobic, and insect resting metabolism is quite insensitive to atmospheric oxygen level, suggesting a large safety margin in the capacity of the tracheal system to deliver oxygen during flight. We tested the sensitivity of flight initiation and metabolism to atmospheric oxygen level in the libellulid dragonfly Erythemis (Mesothemis) simplicicollis using flow-through respirometric measurements of the rate of CO2 emission (<IMG src="/images/symbols/v_dot.gif" WIDTH="9" HEIGHT="14" ALIGN="BOTTOM" NATURALSIZEFLAG="3">CO2). Flight initiations were unimpaired in atmospheric oxygen levels as low as 10 %. However, flight metabolic rate was affected by ambient oxygen level. Flight <IMG src="/images/symbols/v_dot.gif" WIDTH="9" HEIGHT="14" ALIGN="BOTTOM" NATURALSIZEFLAG= "3">CO2 decreased in hypoxic mixtures (5 kPa or 10 kPa oxygen) and increased in hyperoxic atmospheres (30 kPa or 50 kPa oxygen), suggesting that ambient oxygen level influences flight muscle oxygen partial pressure (PO2) and the vigour of flight. These are the first data to show oxygen-limitation of flight metabolism in a free-flying insect. A low safety margin for oxygen delivery during dragonfly flight is consistent with a previous hypothesis that atmospheric hyperoxia facilitated gigantism in Paleozoic protodonates. However, allometric studies of tracheal morphology, and mechanisms and capacity of gas exchange in extant insects are necessary in order to test the hypothesis that the oxygen-sensitivity of aerobic metabolism increases with body size in insects.

scholarly journals Availability of O2 as a Substrate in the Cytoplasm of Bacteria under Aerobic and Microaerobic Conditions

1998 ◽  
Vol 180 (8) ◽  
pp. 2133-2136 ◽  
Author(s):  
Tanja Arras ◽  
Jan Schirawski ◽  
Gottfried Unden
Keyword(s):  
Growth Rates ◽  
Aromatic Compounds ◽  
Bacterial Cells ◽  
Maximal Growth ◽  
Ambient Oxygen ◽  
Regulatory Signal ◽  
Exponential Decrease ◽  
Diffusion Rates ◽  
Oxygen Tensions ◽  
Microaerobic Conditions

ABSTRACT The growth rates of Pseudomonas putida KT2442 and mt-2 on benzoate, 4-hydroxybenzoate, or 4-methylbenzoate showed an exponential decrease with decreasing oxygen tensions (partial O2 tension [pO2] values). The oxygen tensions resulting in half-maximal growth rates were in the range of 7 to 8 mbar of O2 (corresponding to 7 to 8 μM O2) (1 bar = 105 Pa) for aromatic compounds, compared to 1 to 2 mbar for nonaromatic compounds like glucose or succinate. The decrease in the growth rates coincided with excretion of catechol or protocatechuate, suggesting that the activity of the corresponding oxygenases became limiting. The experiments directly establish that under aerobic and microaerobic conditions (about 10 mbar of O2), the diffusion of O2 into the cytoplasm occurs at high rates sufficient for catabolic processes. This is in agreement with calculated O2 diffusion rates. Below 10 mbar of O2, oxygen became limiting for the oxygenases, probably due to their high Km values, but the diffusion of O2 into the cytoplasm presumably should be sufficiently rapid to maintain ambient oxygen concentrations at oxygen tensions as low as 1 mbar of O2. The consequences of this finding for the availability of O2 as a substrate or as a regulatory signal in the cytoplasm of bacterial cells are discussed.

Some responses of the electric ray (Torpedo marmorata) to low ambient oxygen tensions

1978 ◽  
Vol 73 (1) ◽  
pp. 107-117 ◽  
Author(s):  
G. M. Hughes ◽  
I. A. Johnston
Keyword(s):  
Oxygen Tension ◽  
Lactate Concentration ◽  
Torpedo Marmorata ◽  
Water Oxygen ◽  
Blood Ph ◽  
Ambient Oxygen ◽  
End Products ◽  
Lactate And Pyruvate ◽  
Oxygen Tensions ◽  
Pyruvate Ratio

I. Blood samples were taken during prolonged hypoxia experiments in which the inspired water oxygen tension was less than 10 mmHg. The oxygen tension of the post-branchial blood was about 5 mmHg and its pH shows a significant lowering from normoxic levels. 2. The decrease in blood pH is correlated with increases in levels of lactate and pyruvate. The lactate/pyruvate ratio increases during hypoxia. 3. An increase in blood succinate was also found, and strongly suggests the accumulation of multiple anaerobic end-products within the tissues. 4. Recovery of normoxic levels of succinate takes place almost immediately following the restart of ventilation whereas the decrease in lactate concentration is slower. 5. It is concluded that these adaptations may be related to the habitat of the fish at low tide in pools where the Po2 may fall very markedly.

scholarly journals Tracheal Hypertrophy in Mealworms: Design and Plasticity in Oxygen Supply Systems

1989 ◽  
Vol 147 (1) ◽  
pp. 217-235 ◽  
Author(s):  
CATHERINE LOUDON
Keyword(s):  
Total Pressure ◽  
Oxygen Supply ◽  
Cross Sectional Area ◽  
Sectional Area ◽  
Cross Sectional ◽  
Tracheal System ◽  
Primary Mechanism ◽  
Ambient Oxygen ◽  
Supply Systems ◽  
Different Levels

Larval Tenebrio molitor L. (Insecta) were reared in three different levels of oxygen: 21 % (normal), 15 % and 10.5 %, all at 101.3 kPa (=1 atm) total pressure (remainder nitrogen). Some larvae were transferred from one oxygen level to another during development. The main tracheae (branching off from the spiracular tracheae) were of greater cross-sectional area in lower ambient oxygen. Compared to larvae of the same body mass reared in 21 % oxygen, larvae reared in 15 % oxygen had main tracheae 40% larger in cross-sectional area on average, and larvae in 10.5% oxygen had main tracheae 120% larger. This hypertrophy is not consistent with the widely accepted hypothesis that tracheae contribute an insignificant resistance to the net movement of oxygen in insect tracheal systems. The magnitude of the hypertrophy is consistent with predictions from Fick's law of diffusion and with the hypothesis that diffusion is the primary mechanism for oxygen movement in the larval tracheal system of holometabolous insects.

scholarly journals The Effect of Differing Ambient Oxygen Tensions on Wound Infection

1975 ◽  
Vol 181 (1) ◽  
pp. 35-39 ◽  
Author(s):  
THOMAS K. HUNT ◽  
MARK LINSEY ◽  
GUNTA CRISLIS ◽  
MINEITA SONNE ◽  
ERNEST JAWETZ
Keyword(s):  
Wound Infection ◽  
Ambient Oxygen ◽  
Oxygen Tensions

Oncogenesis and the Lucké Virus

1968 ◽  
Vol 26 ◽  
pp. 200-201
Author(s):  
A. E. Vatter ◽  
J. Zambernard
Keyword(s):  
Rna Viruses ◽  
Vegetative State ◽  
Temperature Sensitive ◽  
Structural Level ◽  
Oncogenic Viruses ◽  
Dna Viruses ◽  
Leopard Frogs ◽  
Renal Adenocarcinoma ◽  
Induced Tumors ◽  
Northern Leopard Frogs

Oncogenic viruses, like viruses in general, can be divided into two classes, those that contain deoxyribonucleic acid (DNA) and those that contain ribonucleic acid (RNA). The RNA viruses have been recovered readily from the tumors which they cause whereas, the DNA-virus induced tumors have not yielded the virus. Since DNA viruses cannot be recovered, the bulk of present day investigations have been concerned with RNA viruses.The Lucké renal adenocarcinoma is a spontaneous tumor which occurs in northern leopard frogs (Rana pipiens) and has received increased attention in recent years because of its probable viral etiology. This hypothesis was first advanced by Lucké after he observed intranuclear inclusions in some of the tumor cells. Tumors with inclusions were examined at the fine structural level by Fawcett who showed that they contained immature and mature virus˗like particles.The use of this system in the study of oncogenic tumors offers several unique features, the virus has been shown to contain DNA and it can be recovered from the tumor, also, it is temperature sensitive. This latter feature is of importance because the virus can be transformed from a latent to a vegetative state by lowering or elevating the environmental temperature.

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