Fig. 5. The QA motif is preferentially required for repression of postnotal tissue. Postnotal genotypic series for T3 laterotergite transformation towards T2 thorax as assessed by number of ectopic bristles (blue arrows): (A) Ubx⁺/Ubx⁺ > (B) Ubx^–/Ubx⁺ > (C) Ubx^QA/Ubx^QA > (D) Ubx^QA/Ubx^–. The T3 laterotergite (green line) is normally a thin band of tissue separating T2 and A1 but is expanded in mutants lacking the QA motif (surrounded by green lines marking border). The junction of the haltere and the laterotergite is marked with a green `T3' at the edge of the line. Anterior is upwards, lateral is leftwards and the dorsal midline is rightwards. (A) Ubx⁺/Ubx⁺ T3 half-laterotergites never had bristles, while Ubx^QA/Ubx^– (D) always had bristles (up to a dozen). In the Oregon-R background (shown above), Ubx^QA/Ubx^QA T3 half-laterotergites (C) had 0.972±0.592 bristles, whereas Ubx^–/Ubx⁺ T3 half-laterotergites (B) had 0.017±0.091 bristles (P<10^–20; n=90 and 60, respectively). In the WI129 background (not shown), Ubx^QA/Ubx^QA T3 half-laterotergites had 0.167±0.290 bristles, whereas Ubx^–/Ubx⁺ T3 half-laterotergites had 0.000±0.000 bristles (P<10^–5; n=90 and 60, respectively).