Physiology of a Bacteria-Free Culture of Trichomonas vaginalis. IV. Effect of Hydrogen Ion Concentration and Oxygen Tension on Population

1942 ◽  
Vol 28 (5) ◽  
pp. 369 ◽  
Author(s):  
Garth Johnson
Keyword(s):  
Oxygen Tension ◽  
Trichomonas Vaginalis ◽  
Hydrogen Ion ◽  
Ion Concentration ◽  
Hydrogen Ion Concentration

scholarly journals FACTORS AFFECTING THE PRODUCTION OF CHROMOSOME ABERRATIONS BY CHEMICALS

1956 ◽  
Vol 2 (5) ◽  
pp. 543-555 ◽  
Author(s):  
B. A. Kihlman
Keyword(s):  
Oxygen Tension ◽  
Chromosome Aberrations ◽  
Maleic Hydrazide ◽  
Hydrogen Ion ◽  
Ion Concentration ◽  
Root Tips ◽  
Hydrogen Ion Concentration ◽  
Factors Affecting ◽  
Influence Of Temperature

In the present paper, the results of a study on the influence of temperature, hydrogen ion concentration, and oxygen tension on the production of chromosome aberrations in Vicia root tips by maleic hydrazide (MH), di-(2, 3-epoxypropyl)ether (DEPE), and 8-ethoxycaffeine (EOC), are described. Variations in the hydrogen ion concentration of the treatment solutions did not significantly influence the effect of EOC and DEPE. In contrast, the MH effect was considerably diminished by raising the pH from 4.7 to 7.3. A marked increase in the frequencies of aberrations produced by DEPE and MH was obtained by raising the temperature from 3° to 25°C. The effect of EOC increased with rising temperature up to 12°C. With a further rise in temperature the effect of EOC decreased, so that at 25°C. it was of about the same magnitude as at 3°C. The effect of EOC was completely inhibited, and that of MH partly so, when during the treatment (1) oxygen was excluded from the solution, (2) respiration was inhibited by azide or cyanide, or (3) phosphorylation was uncoupled from respiration by 2, 4-dinitrophenol (DNP). Pretreatments with DNP had a similar effect, but posttreatments did not influence the frequencies of aberrations. The effect of DEPE was unchanged by anoxia. Pre- or posttreatments with DNP did not change the total number of aberrations produced by DEPE, but the appearance of the effect was considerably delayed. The results are discussed.

Some Aspects of the Arterial Response to Venous Occlusion in Man

1983 ◽  
Vol 65 (1) ◽  
pp. 1-8 ◽  
Author(s):  
M. A. Ireland ◽  
P. Davies ◽  
W. A. Littler
Keyword(s):  
Blood Flow ◽  
Oxygen Tension ◽  
Venous Blood ◽  
Venous Occlusion ◽  
Hydrogen Ion ◽  
Ion Concentration ◽  
Biphasic Response ◽  
Hydrogen Ion Concentration ◽  
Autonomic Blockade

1. Plethysmographic blood flow records made after venous occlusion of the forearm showed a biphasic response which was first vasodilator and then vasoconstrictor. 2. The myogenic nature of the vascoconstrictor phase was confirmed in eight subjects after total autonomic blockade with atropine, propranolol, phentolamine and guanethidine. 3. Forearm venous blood demonstrated a rise in hydrogen ion concentration and a fall in oxygen tension during venous occlusion, which may contribute to the vasodilatation phase.

scholarly journals THE EFFECT OF HYDROGEN ION CONCENTRATION UPON THE INDUCTION OF POLARITY IN FUCUS EGGS

1937 ◽  
Vol 21 (1) ◽  
pp. 57-70 ◽  
Author(s):  
D. M. Whitaker ◽  
E. W. Lowrance
Keyword(s):  
Oxygen Tension ◽  
Concentration Gradient ◽  
Sea Water ◽  
Capillary Tube ◽  
Hydrogen Ion ◽  
Developmental Pattern ◽  
Ion Concentration ◽  
Hydrogen Ion Concentration ◽  
Ph Values

1. When a Fucus egg develops near one end in a close fitting capillary tube of pyrex glass or silica (quartz), diffusion of substances passing to and from the egg is more impeded on the side of the egg toward the far end of the tube. 2. The egg therefore develops in a gradient of its own diffusion products, and of oxygen tension. 3. More than 600 eggs have been reared, each near one end in a capillary, in sea water at various regulated and measured pH values. 4. When the medium, which is initially homogeneous inside and outside the capillary, is initially at pH 6.5 to 7.6, nearly all of the eggs develop rhizoid protuberances on the sides of the eggs toward the far ends of the capillaries. This is on the sides of the eggs where the concentration of substances diffusing from the eggs is greatest. 5. The polarity and developmental pattern of the egg is thus determined either by a concentration gradient of products diffusing from it, or by a gradient of oxygen tension. The former interpretation is favored. 6. This is regarded as an extension of earlier observations that rhizoid protuberances form on the sides of two neighboring eggs in the direction of the neighbor if the sea water is acidified. 7. It appears hardly possible that a mitogenetic effect could be responsible for the response of an egg to its own diffusion gradients. 8. When the medium is made more basic, the percentage of the eggs which form rhizoid protuberances toward the far end of the tube decreases to about 20 or 25 per cent between pH 8.1 and 8.6. The response of the egg to the gradients which it produces is thus statistically reversed. The determination of the polarity of the eggs by the diffusion gradients does not become as complete in alkalinized as in acidified sea water. 9. When the pH of the sea water is elevated to 9.1 or 9.2, salts precipitate out. The type of development is altered and the control of the diffusion gradients over the polarity of the eggs decreases.

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