Delayed activation of glycogen synthase adjusted to the effective storage function of fat body in the premetamorphic instar of the silkworm, Bombyx mori

Abstract 1. 1. An in vitro incubation of fat body with [ 14 C]acetate or [ 14 C]glucose showed that there was the developmental separation of glycogenesis from lipogenesis during the last (fifth) instar of the silkworm, Bombyx mori . 2. 2. In the penultimate (fourth) instar, both lipogenesis and glycogenesis coincidentally occurred without any temporal separation. Whereas, allatectomy from day 1 fourth instar larvae caused to induce precocious pupation and delayed glycogenesis to separate from lipogenic phase. 3. 3. Although total activity of glycogen synthase assayed in the presence of glucose 6-phosphate remained unchanged, the conversion of glycogen synthase b to a form took place in fat body which was active in glycogenesis.