XVIII. Alterations of the Nature of RNA Synthesized in Isolated Fat Body Cell Nuclei as a Result of Ecdysone and Juvenile Hormone Action

Abstract

The RNA synthesized in isolated fat body cell nuclei of blowfly larvae under the influence of ecdysone and juvenile hormone was studied by sucrose density centrifugation and RNA-DNA-hybridization. RNA produced in isolated nuclei of larvae in the early third instar has a polydisperse sedimentation pattern, showing a maximum at about 14 S, while RNA synthesized in nuclei of larvae in a later developmental stage has, in average, lower sedimentation coefficients. No significant differences in sedimentation properties could be seen between RNA of control and hormone-treated nuclei. An investigation of the hybridization of RNA synthesized in hormone-treated nuclei showed that the RNA produced under the influence of ecdysone or juvenile hormone is qualitatively different from that of the controls. This points to a specific effect of the hormones on the genome. The antagonistic effect of ecdysone and juvenile hormone on RNA synthesis is discussed on the basis of hybridization studies.