Fig. 6. Timed misexpression of Ds, induced in sal-gal4/tubgal80^ts; UAS-ds/+ wings using temperature upshifts (induction) or downshifts (suppression). (A,B) Percentage of flies showing PCP defects. Dark gray indicates strong defects; light gray, weak defects. The relationship between the absolute age of the larvae or pupae and the developmental stage was altered by the different rearing temperatures, thus the approximate third instar stages are indicated. Flies reared continuously at 20°C did not show any adult PCP defects or ectopic anti-Ds staining in wing discs (C), whereas those reared continuously at 30°C showed strong hair reorientation (similar to that seen in Fig. 3B,E). (D-H) Anti-Ds staining in pupal wings. A temperature upshift at 0 hours AP induced scattered ectopic anti-Ds staining by 5 hours AP at 30°C (D, approximately equivalent to 6 hours AP at 25°C) and strong misexpression in the broad sal-gal4 pattern by 22 hours AP at 30°C (E, approximately equivalent to 24 hours AP at 25°C). A temperature downshift at 0 hours AP did not suppress ectopic anti-Ds staining by 5 hours AP at 20°C (F, approximately equivalent to 4 hours AP at 25°C) but did by 24 hours AP at 20°C (G, approximately equivalent to 17-19 hours AP at 25°C). The narrow stripe of Ds expression in G is also observed in wild-type wings at this stage (H), and differs in level and extent from that driven by sal-gal4 (E).