Fig. 4: Transcription factors transform dorsal branch and dorsal trunk cells.

a–f Ectopic expression of Spalt or Tom in the dorsal branch activates Delta which is normally expressed in the dorsal trunk. Dorsal branches of control, UAS-sal, or UAS-Tom flies were stained with an antibody against Delta (a, c, e), and DNA was stained with DAPI (b, d, f). g–j Ectopically expressed Kni induces Serpentine (Serp) expression. The dorsal trunk of control or UAS-kni flies were stained with an antibody against Serp (g, i) and DAPI (h, j). a–j Each experiment was repeated independently with similar results for four times. k, l UMAP plot representing expression of Tom (k) and serp (l) in each cluster of tracheal cells. m, Box plot represents Delta levels in control (n = 20), UAS-sal (n = 12) or UAS-Tom (n = 12) flies. n Box plot showing Serp contents in control (n = 14) or UAS-kni (n = 12) flies. m, n Data are presented as median with minima and maxima. 25th–75th percentile (box) and 5th–95th percentile (whiskers) as well as outliers are indicated in the box plots. More than four biologically independent experiments were performed. An unpaired two-tailed t-test was used for all statistical analyses. No adjustments were made for multiple comparisons. Genotypes: a, b kni-Gal4/+; tub-Gal80^ts/+. c, d kni-Gal4/UAS-sal; tub-Gal80^ts/+. e, f kni-Gal4/+; UAS-Tom/tub-Gal80^ts; UAS- Tom/+. g, h sal-Gal4/tub-Gal80^ts. i, j UAS-kni/+; sal-Gal4/tub-Gal80^ts. DT dorsal trunk, DB dorsal branch, TC transverse connective, ASP air sac primordium, VB visceral branch, SB spiracular branch, PC progenitor cells. Scar bars: 50 μm (a–f), 20 μm (g–j). Source data are provided as a Source Data file.