Fig. 1. Orcein staining of polytene chromosomes from third instar larvae. (A) Detail of the chromocentre (arrow) from HA:FL4D larvae after daily heat-shocks (hs) or without heat-shocks. (B) Polytene chromosomes from males and females containing a heat-inducible Su(var)3-7 transgene. Homozygous HA:FL4D males and females kept at 18°C (no hs) or submitted to daily heat-shock at 35°C from the second larval instar stage (hs) or three daily heat-shocks from the first instar larval stage (hs+). Arrows indicate the X chromosome.