Fig. 6. Mesodermal or ectodermal overexpression of brk causes a decrease in tin (A,B,E,F), Eve (C,D) and dpp (G,H) expression. (A,C) Late stage 11 wild-type embryos. (B,D) Late stage 11 twi-Gal4;24B-Gal4>UAS-brk embryos exhibiting a severe reduction in tin expression (B) and in the number of Eve clusters (D). (E) Mid-stage 11 ZKr-Gal4>UAS-brk embryo exhibiting a selective reduction of cardiac (arrow), but not visceral (arrowhead) tin expression in the domain affected by the ZKr-Gal4 driver (brackets). (F) 69B-Gal4>UAS-brk embryo showing a slight reduction in cardiac tin expression (arrow) at stage 13, but not at earlier stages (data not shown). (G) Mid-stage 11 ZKr-Gal4>UAS-brk embryo exhibiting a selective reduction of dorsal ectodermal dpp expression (arrow) in the Kr domain (brackets). (H) 69B-Gal4>UAS-brk embryo showing a moderate reduction in dorsal ectodermal dpp expression (arrow) at stage 13, but not at earlier stages (data not shown).