Heat shock and phenocopy induction in Drosophila.

Differentiation of the single cells that yield bristles and hairs in Drosophila has been examined by studies of phenocopies induced by heat shock. Phenocopies that resemble the mutants hook and javelin are produced by application of the stress within narrow and specific time ranges during metamorphosis. Double phenocopies can be induced by successive heat shocks at appropriate time intervals. Phenocopy production may be related to heat shock effects on RNA synthesis through a feedback inhibition of transcription by heat shock proteins.