Fig. 3. Headless flies result from interference with ey functions, which depends on DNA-binding activities different from that of Ey. Left eyes of flies are shown in scanning electron micrographs. (A) UAS-Ey rescues the headless phenotype in ey-Gal4/UAS-Gsb-7; UAS-Ey/+ flies almost completely to a small-eye phenotype. (B) A different small-eye phenotype is produced in ey-Gal4/+; UAS-Ey/+ flies. (C) ey-Gal4/+; UAS-GE-8/+ flies, which carry mutations in amino acids 42 (Q mutated to I), 44 (R to Q) and 47 (H to N) in the paired domain of UAS-Gsb changing its DNA-binding specificity to that of the Ey paired domain, exhibit little or no interference with ey functions and display, in four out of six lines, a phenotype similar to wild type (D) or, in two lines, a weak phenotype similar to ey-Gal4/+; UAS-Ey/+ flies (B).