Fig. 8. bab controls the morphology of abdominal segments. Female tergite pigmentation in wild type (A) and in loss-of-function bab mutants of increasing phenotypic strength: (B) bab^A128/ bab^A128 (C) bab^Dl/ bab^Dl and (D) bab^AR07/Df(3L)Fpa2, a null mutant. Ectopic dark pigmentation in the anterior portion of the tergites is indicated by asterisks. (F) In a Df(3L)Fpa1/Df(3L)Fpa2 female, the two tergite plates of A7 are fused (arrowhead) and enlarged, and contain more bristles in comparison with wild type (E). In addition, the A6 tergite is enlarged (double arrow in E,F). (G) Wild-type and (H) Df(3L)Fpa1/Df(3L)Fpa2 male abdomina, showing ectopic pigmentation in bab mutant tergites. Ventral view of the abdomen of (I) wild-type, (J) Df(3L)Fpa1/Df(3L)Fpa2 and (K) bab^AR07/Df(3L)Fpa2 females, and a (L) wild-type male showing features of the A6 and A7 sternites, and the female vaginal plates (arrows in I,K). (M-P) Ubiquitous overexpression of bab2 causes a loss of pigmentation. A Hsp70-Gal4/+;UAS-bab2^66/3/+ female (M) and male fly (P), raised at 25°C, lack dark pigmentation in A6. The loss of pigmentation is stronger in posterior than more anterior abdominal segments. (N) In a Hsp70-Gal4/+;UAS-bab2^66/3/+ female fly, raised at 18°C until late 3rd instar and at 32°C during the pupal stage, the tergite primordia have not fused. (O) A Hsp70-Gal4/+;UAS-bab2^51A3/+ male fly, raised at 25°C, shows reduced pigmentation in A5 and A6. In all panels, anterior is upwards and segment identity is indicated by numbers.