Abstract
The activity of total RNA synthesis including fibroin mRNA in the cultured posterior silk gland of Bombyx mori was dependent on the developmental stage of larva from which the silk gland was dissected out. The majority of the RNA synthesized in the posterior silk gland cultured for 24 hr was ribosomal RNA and transfer RNA at all investigated stages. The synthesis of fibroin mRNA primarily decrease by the application of the molting hormone, 20-hydroxyecdysone, whereas the hormone stimulated the synthesis of both ribosomal and transfer RNAs.
