Effects of Ecdysterone and the juvenile hormone analogue methoprene on protein, RNA and DNA synthesis in wing discs of Calliphora vicina.

The protein, RNA and DNA content of wing discs increase exponentially during the last larval instar. Biosynthesis of protein, RNA and DNA was studied by injecting labelled precursors into larvae or white prepupae and measuring the incorporation in the wing discs dissected out after an appropriate time. Protein synthesis is stimulated by ecdysterone, methoprene has no effect. Biosynthesis of rRNA is increased in wing discs of white prepupae after ecdysterone or methoprene injection. Methoprene inhibits the synthesis of mRNA, while ecdysterone has no clear-cut effect within the limits of our method (gel electrophoretic analysis). Ecdysterone and methoprene have no detectable influence on incorporation of thymidine into DNA, but the incorporation label from uridine into DNA is diminished; this effect may be due to changes in the precursor pool.