Transcription of Drosophila small hsp-tk hybrid genes is induced by heat shock and by ecdysterone in transfected Drosophila cells.

Hybrid genes containing the 5' region of Drosophila heat shock protein (hsp) genes, ligated to the herpesvirus thymidine kinase (tk) gene, were transfected into Drosophila line S3 cells. Constructions containing sequences upstream from hsp70, or from any of the small hsp genes, showed heat-inducible tk expression. Ecdysterone-inducible tk expression was seen only in transfections with small hsp-tk hybrid genes. Plasmids containing a synthetic "heat shock consensus sequence" or a deletion of the hsp23 upstream region were totally inactive in transfection studies.