RNA and DNA puffs in polytene chromosomes of rhynchosciara: inhibition by extirpation of prothorax.

In the giant polytene chromosomes, gene amplification is made visible by formation of DNA puffs, and gene transcription is made visible by formation of RNA puffs. Ligation of the anterior portion of the larva at the end of the fourth larval instar inhibited the formation of the DNA puffs that normally develop at this stage and caused regression of RNA puffs.