ON MECHANISM OF HORMONE ACTION .13. STIMULATING EFFECTS OF ECDYSONE, JUVENILE HORMONE AND IONS ON RNA SYNTHESIS IN FAT BODY CELL NUCLEI FROM CALLIPHORA ERYTHROCEPHALA ISOLATED BY A FILTRATION TECHNIQUE

The effects of ecdysone, juvenile hormone, sodium and potassium ions and some interactions among these factors on RNA polymerase activity were investigated in fat body cell nuclei, isolated from 5-6-day-old larvae by a filtration technique. 1. 1. Sodium ions in a concentration of 50 mM stimulated the RNA synthesis of fat body cell nuclei. This effect could not be observed with potassium ions and was independent of ecdysone. 2. 2. Ecdysone stimulated the RNA synthesis of fat body cell nuclei alone or in the presence of sodium or potassium ions. This effect seemed to be independent of the sodium stimulation. 3. 3. Juvenile hormone was capable of stimulating RNA synthesis of isolated fat body cell nuclei, but this stimulation was dependent on the developmental stage of the animals used. Nuclei isolated from animals with an average weight of 73 mg (5-day-old) responded to juvenile hormone with higher RNA synthesis as the controls, while nuclei of older animals with an average weight of about 98 mg showed no stimulation at all. 4. 4. The effects of ecdysone and juvenile hormone alone on the RNA synthesis could be inhibited by incubating the nuclei with both hormones together. © 1969.