Figure 7.

Kinetics of recruitment of Spt6 to heat shock loci. (A) Spt6 recruitment at major heat shock loci 87A and 87C on untreated (0′) polytene chromosomes or on 2- and 20-min heat shock–treated chromosomes. A DNA Hoechst stain is shown for the uninduced sample to allow mapping of the non-puffed heat shock loci. (B) Recruitment of Spt6 to heat shock loci on polytene chromosomes in hsf⁴ mutant. Shown are the 87A and 87C heat shock loci (left) and the developmentally active locus at 3C (right) after a 20-min heat shock within the same polytene chromosome spread. 87A and 87C display little or no staining with Spt6 antibody, whereas Spt6 staining at the developmentally active locus at 3C persists.