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Biol Bull 66: 361-376. (June 1934)
© 1934 Marine Biological Laboratory
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THE INFLUENCE OF HYPERTONIC AND HYPOTONIC SEA WATER ON THE ARTIFICIAL ACTIVATION OF STARFISH EGGS

RALPH S. LILLIE 1

1 From the Department of Physiology, University of Chicago, and the Marine Biological Laboratory, Woods Hole, Massachusetts

Brief treatment of unfertilized starfish eggs with hypertonic sea water increases the rate of activation by subsequent exposure to butyric acid. This effect may be described as a sensitization to the activating influence of the acid. The curve representing the relation between the duration of the hypertonic treatment and the rate of acid-activation resembles the bimolecular reaction isotherm.

In general the experimental facts of acid-activation (and of heat-activation) are consistent with the following simplified schema. Activation is the physiological result of the accumulation of a reaction product, called (provisionally) "the activating substance" (substance A) which is formed by the chemical union of two chief compounds. One of these, called (after the analogy with light-sensitization) the "sensitizing substance" (substance S), is already present in the egg; the other, the "acid-product" (substance B), is set free (e.g., by hydrolysis) under the influence of the activating acid. The equation S + B = A symbolizes this hypothetical activation-reaction.

Treatment with hypertonic sea water increases the concentration of S at the site of the activation-reaction, through the abstraction of water and promotion of dehydrolytic synthesis. The resulting increase in the rate of acid-activation is thus explained. Treatment with dilute sea water should theoretically have the reverse effect, but in this case the experimental evidence is conflicting.

The acid-product B appears to be formed at a rate proportional (through a certain range) to the concentration of acid; it is regarded as being set free by the hydrolysis of some normal egg-component at a rate controlled by the cH. The special hypothesis that the hydrolyzed compound is a phosphagen ester has, however, received no support from test experiments.

The hypothesis that heat-activation is an effect of the formation of lactic acid by glycolysis is also not supported by experiments with iodoacetate and fluoride.






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