FIG. 2.

dAda2a and dGcn5 mutants display phenotypes indicating developmental defects. (A) dAda2a¹⁸⁹ mutants fail to pupariate or form malformed pupae. Third-instar dAda2a¹⁸⁹ larvae reach sizes similar to those of their wild-type (wt) siblings but do not start wandering and fail to evert spiracles (arrows), and only after 8 to 10 days in L3 do some of them form primitive pupa-like structures covered with brownish cuticle. (B) Imaginal discs of dAda2a¹⁸⁹ and dGcn5^E333st third-instar larvae are underdeveloped compared with similarly aged wild-type controls. During their extended L3 stage, the imaginal discs of dAda2a and dGcn5 mutants grow and reach the size of the fully developed wild-type discs after 8 to 10 days of L2/L3 molting, but they are abnormal in regards to both their shape and their structure. (C) Polytene chromosomes of dAda2a¹⁸⁹ and dGcn5^E333st mutants display similarly abnormal structures with respect to reduced condensation, short arms, and distorted banding pattern. Wild-type (wt) dAda2a and dGcn5 transgenes or a Gcn5 transgene lacking the PCAF region restores the normal chromosome structure of the corresponding mutants, while dGcn5 transgenes with a deletion in the ADA-interacting region or in the HAT domain fail in the rescue.