Figure 2.

Distribution of dCDK12 and dCyclin T on polytene chromosomes. (A) Chromosomes from NHS larva reacted with anti-dCDK12 (red), anti-dCyclin T (green), or DAPI (blue: “DNA”). The white arrow indicates a developmental puff that stains strongly for CDK12, but weakly for Cyclin T. Red and green dots in the Merge panel indicate bands that are predominantly red (CDK12) or green (Cyclin T), respectively. (B) Chromosome set from a heat-shocked larva (20 min at 37°C) analyzed as for A. Red and green dots in the Merge panel indicate bands that are almost exclusively red (CDK12) or green (Cyclin T), respectively. (C) Isolated chromosome segment (non-heat shock) showing CDK12 (red) and Cyclin T (green). Prominent developmental (ecdysone-induced) puffs 74E and 75B are labeled. Colored dots indicate sites that stain almost uniquely for the corresponding protein. (D) Segment of chromosome 3R (heat shock) with the merged image aligned between images of CDK12 and Cyclin T. Major heat-shock loci are labeled (87A and 87C). Dotted lines facilitate comparisons between red and green images.