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.

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

1937 ◽  
Vol 20 (3) ◽  
pp. 491-500 ◽  
Author(s):  
D. M. Whitaker
Keyword(s):  
Inductive Effect ◽  
Sea Water ◽  
Hydrogen Ion ◽  
Developmental Pattern ◽  
Ion Concentration ◽  
Hydrogen Ion Concentration

1. The eggs of Fucus furcatus develop perfectly in sea water acidified to pH 6.0. They are retarded at pH 5.5. At pH 5.0 they do not develop, nor do they cytolize. 2. In normal sea water in the dark at 15°C., eggs develop rhizoids on the sides in the resultant direction of a mass of neighboring eggs. The polarity and the whole developmental pattern of the embryo is thereby induced. This inductive effect does not operate, however, unless the directing mass is an appreciable aggregation of cells (10 or more), or unless there are numerous other eggs in the dish. A group of five eggs alone in a dish do not carry out mutual inductions. Two eggs alone in a dish do not develop rhizoids toward each other. 3. When the sea water is acidified to pH 6.0 all sizes of aggregations carry out mutual inductions. Two eggs alone in a dish now develop rhizoids on the sides toward each other, provided they are not more than about 4 egg diameters apart. 4. Increased hydrogen ion concentration thus augments or intensifies the mutual inductive effect. 5. This may explain why only larger masses of eggs show inductions in normal sea water, since presumably the larger masses considerably increase the hydrogen ion concentration locally. 6. The nature of the inductive action is discussed. 7. In acidified sea water at pH 6.0, compared with normal sea water at pH 7.8–8.0, the rhizoids originate and extend with a strongly increased downward component. The substrate then forces further extension or growth of the rhizoid to be in the plane of the substrate.

scholarly journals The Hydrogen-ion Concentration of Sea Water

Nature ◽  
1923 ◽  
Vol 111 (2778) ◽  
pp. 132-133
Author(s):  
J. J.
Keyword(s):  
Sea Water ◽  
Hydrogen Ion ◽  
Ion Concentration ◽  
Hydrogen Ion Concentration

570. A medium for the simultaneous enumeration and preliminary identification of milk microflora

1955 ◽  
Vol 22 (1) ◽  
pp. 43-47 ◽  
Author(s):  
Kathleen O. Donovan ◽  
J. M. Vincent
Keyword(s):  
Acid Production ◽  
Skim Milk ◽  
Biochemical Properties ◽  
Viable Count ◽  
Hydrogen Ion ◽  
Ion Concentration ◽  
Hydrogen Ion Concentration ◽  
Pasteurized Milk ◽  
Preliminary Identification

A medium has been developed that permits the viable count of milk bacteria to be combined with the determination of biochemical properties likely to be important in milk itself. This has involved the modification of standard glucose-tryptone skim-milk agar by incorporation of two indicators to detect alkali as well as acid production, substitution of lactose for glucose, and increasing the quantity of skim milk for the detection of proteolysis and casein precipitation. The medium has proved particularly valuable in the study of the thermoduric flora of pasteurized milk. The phenomenon of casein precipitation is, however, less reliably determined than are changes in hydrogen-ion concentration and proteolysis.

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