UPTAKE OF RADIOACTIVE GLUCOSE AND AMINO ACIDS AND THEIR UTILIZATION FOR INCORPORATION INTO PROTEINS DURING MATURATION AND FERTILIZATION OF THE EGGS OF ASTERIAS FORBESII AND SPISULA SOLIDISSIMA

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Abstract
1. In the eggs of Asterias forbesii the rate of total uptake of C14-glucose and of L-valine-1-C14 declines during maturation both in unfertilized and fertilized eggs. The rate of uptake of S35-L-methionine remains constant throughout maturation. After completion of maturation the rate of uptake is greatly increased in the fertilized eggs, whereas in the unfertilized ones it either continues to decline or remains constant. 2. The rate of incorporation of C14 from glucose and of C14-valine and S35-methionine into proteins undergoes a slight acceleration during maturation both in unfertilized and fertilized eggs. After the formation of the second polar body, the rate of incorporation declines in the unfertilized eggs while continuing to increase in the fertilized ones. 3. Activation, either spontaneous or artificial, brings about a rapid increase of the rate of uptake of the precursors used. 4. In the eggs of Spisula the rate of uptake of L-valine-1-C14 and of its incorporation into proteins is very low in the unfertilized eggs. A tremendous increase both in the rate of uptake and of incorporation into proteins takes place a few minutes after the fertilization-induced breakdown of the germinal vesicle. 5. The significance of these observations is discussed in relation to the problem of the release of the metabolic inhibition of the unfertilized egg upon fertilization, and in comparison with the results obtained in the sea urchin egg.