<i>ptc</i> mutants start expressing DSRF earlier.

<p>(A,B) Stage 13 wt (A, A′) and <i>ptc</i> mutant (B, B′) embryos carrying the btlmoeRFP reporter stained with anti-RFP to visualise the tracheal cells and anti-DSRF antibody to mark all terminal-cell nuclei. <i>ptc</i> embryos start expressing DSRF earlier than the wt. Scale bars are 10 μm. (C,D) Late stage 13 wt (C, C′) and <i>ptc</i> mutant (D, D′) embryos stained with anti-Dof and anti-trh antibody. All <i>ptc</i> embryos analysed have higher levels of Dof in DB tip-cells (arrowheads in D′ and D″, n = 12). Scale bars are 10 μm. (E,F) Detail of stage 16 GBs stained with 2A12 and anti-DSRF in wt (E) and <i>ptc</i> embryos (F). (G,H) Detail of stage 16 GBs from embryos carrying the pruned-lacZ reporter stained with 2A12 and anti-ßgal in <i>pruned</i> (DSRF) mutant (G) and double <i>ptc pruned</i> mutant. Terminal cells in <i>pruned</i> mutants do not extend their terminal lumen in wt or <i>ptc</i> mutant backgrounds (asterisks). Scale bars are 25 μm. DSRF* means that in panels E, F the presence of this protein is detected by the antibody, whereas in panels G,H terminal cells are marked by βgal expression. Anterior is left in all panels.