GLYCOGEN METABOLISM AND CHANGES IN THE ACTIVITIES OF PHOSPHORYLASE, PHOSPHOFRUCTOKINASE AND PYRUVATE KINASE DURING DEVELOPMENT OF SEA URCHIN EGGS

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Abstract
The glucose and glycogen contents of sea urchin eggs and embryos were measured enzymatically. Unfertilized eggs of Hemicentrotus pulcherrimus and Anthocidaris crassispina contain about 20.9 and 24.4 .mu.g of glycogen/mg protein, respectively. As for glucose, unfertilized eggs of Hemicentrotus and Anthocidaris contain about 0.7 and 1.9 .mu.g/mg protein, respectively. Glycogen consumption during embryonic development differs with different species of sea urchins. In Anthocidaris, glycogen decreases significantly after fertilization. The oxidation of glucose and glycogen accounts for about 50% of O2 consumed until the early blastula stage in this species. The contribution ratio of glucose and glycogen to the overall energy pool becomes less than 10% at later stages. In Hemicentrotus, the glycogen content remains unchanged until the early blastula stage and thereafter decreases. The importance of glucose and glycogen as an energy fuel seems little throughout the development of Hemicentrotus. Activities of phosphorylase, phosphofructokinase and pyruvate kinase were measured at various embryonic stages in both species of sea urchins. The difference between the 2 spp. in the consumption of glucose and glycogen cannot be elucidated by the differences in the activities of these enzymes.