Fig. 7.
Increasing or decreasing brk levels in the spiracular chamber engenders the opposite effects on dppMX-lacZ expression. Staged embryos in dorsal view with anterior to the left. Wild type embryos (A, D, G, J, M), brkM68 embryos (B, E, H, K, N) and embryos with UAS.Brk driven by PS{Gal4}8B4B (C, F, I, L, O) were double-labeled for Cut in red and dppMX-lacZ in green. PS{Gal4}8B4B driving UAS.Brk leads to overexpression of Brk in the dpp posterior spiracle pattern. Cut expression in the Malphigian tubules, illustrated with a red arrowhead in stage 13 embryos, was utilized for stage matching. Expression of Cut and lacZ in the spiracular chamber is indicated with a white arrowhead. (A, B, C) Stage 13. In wild type dppMX-lacZ is strongly expressed in the spiracular chamber. In brk mutants dppMX-lacZ spiracular chamber expression is also present but it is barely visible in UAS.Brk embryos. (D, E, F) Stage 14. In wild type dppMX-lacZ expression weakens in the spiracular chamber. In brk mutants dppMX expression is present and is still faint in UAS.Brk embryos. (G, H, I) Stage 15. In wild type dppMX-lacZ expression continues to weaken in the spiracular chamber but is now present in the dorsal trunk branches. In brk mutants dppMX-lacZ spiracular chamber and dorsal trunk branch expression are roughly equal to wild type. dppMX-lacZ spiracular chamber expression remains faint in UAS.Brk embryos and is below wild type in the dorsal trunk branches. (J, K, L) Stage 16. In wild type dppMX expression is weakly visible in the spiracular chamber but is now strong in the dorsal trunk branches. In brk mutants dppMX-lacZ spiracular chamber and dorsal trunk branch expression remains roughly equal to wild type levels. dppMX-lacZ expression is absent in the spiracular chamber and very faint in the dorsal trunk branches in UAS.Brk embryos. (M, N, O) Stage 17. In wild type dppMX-lacZ expression is absent from the spiracular chamber and very strong in the dorsal trunk branches. In brk mutants dppMX-lacZ ectopic spiracular chamber expression is present while dorsal trunk branch expression remains roughly equal to wild type. dppMX-lacZ expression is again absent in the spiracular chamber and very faint in the dorsal trunk branches in UAS.Brk embryos.