. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. PHENOLS AND STIMULATION OF RESPIRATION 217 EFFECT OF CHANGING THE INTERNAL pH If the anion is the active form within the cell, then by increasing the internal pH (keeping the external pH constant) a lower total concentration of the substituted phenol should be required to give the optimum respiratory stimulation or the reversible block to cleavage. It is possible to increase the internal pH by the addition of a weak penetrating base such as ammonia. The pH change is readily demonstrated by first staining the eggs with neutra
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. PHENOLS AND STIMULATION OF RESPIRATION 217 EFFECT OF CHANGING THE INTERNAL pH If the anion is the active form within the cell, then by increasing the internal pH (keeping the external pH constant) a lower total concentration of the substituted phenol should be required to give the optimum respiratory stimulation or the reversible block to cleavage. It is possible to increase the internal pH by the addition of a weak penetrating base such as ammonia. The pH change is readily demonstrated by first staining the eggs with neutral red, and, after washing, immersing them in the ammonia solution. The extent to which the red color fades (neutral red changes from red to yellow between pH and pH ) gives the increase in internal pH that has occurred. The effect of increasing the internal pH on the concentration of dinitrophenol required for reversible cleavage block was investigated with eggs of Urechis. The solutions were prepared from carbonate- TABLE II Cleavage inhibition of Urechis eggs with 2, 4-dinitrophenol in ammoniacal sea water. Experimental and control solutions both prepared from carbonate-free sea water and buffered at pH with glycylglycine. Concentration of 2, 4-DNP Cleavage in am- monia solution Cleavage in con- trol solution (Molar) (per cent) 0 99 X 10~4 ...95 X 10~4 0 X 10~4. 0 (per cent) 99 95 95 90 free sea water using the glycylglycine buffer and adjusting the pH with ammonia. In the control solutions NaOH was used instead of ammonia. It was found in the first place, that when sufficient am- monia was present to effect an increase in internal pH, cleavage was interfered with or proceeded abnormally. These same solutions when used on unfertilized eggs gave artificial parthenogenesis. With solu- tions weak enough in ammonia to have no effect on cleavage and no activating effect on unfertilized eggs there was no observable effect on the internal pH. We were unable t
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Keywords: ., bookauthorlilliefrankrat, booksubjectbiology, booksubjectzoology
