Puffing activities and binding of ecdysteroid to polytene chromosomes of Drosophila melanogaster.

There was a good correlation between the sequential and temporal puffing activity induced by 20‐hydroxy‐ecdysone and the binding of ecdysteroid hormone to these puffs, and additional factors besides steroid hormone are necessary for sequentially regulating puffing and concomitant gene activity during development from larvae to prepupae.