Fig. 6. Overexpression of HP1 leads to SuUR mutant phenotype. UR level of the region 89E in salivary glands polytene chromosomes of the hs-HP1 homozygous was measured without (lane 1) and with (lane 2) heat-shock treatments. The Southern blot was hybridized with the abd-A and rosy (control) probes; the ratios of abd-A-specific hybridization signals to rosy-specific hybridization signals are given below the blot.