Fig. 1.

Pu and Catsup are involved in tracheal development. (A) Comparison of β-Gal (directed by the trachea-specific trachealess promoter) and Punch expression patterns in the trachea. β-Gal expression in 1-eve-1 marks all tracheal cells at all stages while Punch is expressed most abundantly in the trachea from stage 12 to stage 14. The insets show enlarged views of individual tracheal subunits stained for Punch. Arrows point to the site from which the dorsal trunk extends. The expression of Punch fades after stage 14. Bars are 50 μm. (B) Close-up views of portions of single tracheal subunits at stage 12, 14 and 15, double stained for Punch (red) and Crb (green). Crb is a transmembrane protein and Punch overlaps with Crb completely in the trachea at stage 12. At stage 14 Punch still shows extensive overlap with Crb in addition to some intracellular localization (arrowhead). At stage 15, peripheral localization of Punch is diminished (arrow) with an increased expression in the lumen (open arrow). Bars are 10 μm. (C) y w embryos were stained with anti-Ple or anti-Catsup antibodies, as indicated. The insets show enlarged views of two tracheal subunits with Ple or Catsup expression. The higher level of general staining indicate that the two proteins are expressed in multiple tissues. Bars are 10 μm. (D) Embryos of indicated genotypes were stained with a tracheal lumen-specific antibody 2A12. Unless specified, all embryos are oriented with anterior to the left and dorsal side up. (a) y w represents wild-type. The major tracheal branch that runs along the length of the embryo, dorsal trunk, is marked (DT). (b-c) Embryos homozygous for two Pu alleles Z22 and K5-2 show disrupted tracheal network. The insets highlight ectopic branches (arrowheads). (d) shi² temperature-sensitive mutant embryos were collected at 25° for 7 hr and then incubated at 30° for 7 hr. The inset highlights ectopic branches (arrowheads). (e) An awd^j2A4 mutant. The inset highlights ectopic branches (arrowheads). (f-g) Two Catsup²⁶ mutant embryos showing moderate and severe phenotypes, respectively. Empty arrows in (f) mark the gaps in the dorsal trunk, while (g) shows almost no branch migration. (h) Ventral view of a btl^H82Δ3 mutant embryo showing little branch migration. Bars are 50 μm.