Characterization of wild-type midgut MET and of Srp down-regulation in wild-type and sna,twi embryos. (a–f, i, j, l, and m) Wild-type (a–f, i, and j) and sna,twi (l and m) embryos stained for Baz (green, a–f) and βPS (magenta, a–f) or Srp (green, i–m) and Hnt (magenta, i–m). White arrows (a and d–f) point to Baz localized apically in midgut cells, and red arrows (d–f) to βPS localized basally. Yellow dotted lines outline the posterior midgut. (g) Schematic depicting where measurements of fluorescence intensity were performed. The length of each cell within the ventral posterior region of the midgut was measured (boxed region) by drawing lines in the plane of the cell, from 1 µm above the apical membrane (A) of midgut cells to 1 µm below the basal surface (B) of the visceral mesoderm in a single z-slice. (h) FWHM was measured by calculating the width of the peak at half maximum peak height per embryo. Peak height was measured by finding the maximum value of peaks within specific ranges of the cell length (0–10 µm for apical peaks and 10–20 µm for basal peaks). (k and n) Dot plots of Srp levels in wild-type (k) or sna,twi (n) embryos. The Srp level per embryo at each stage is calculated as the mean gray value of 30 individually measured nuclei, and each dot represents one embryo. Each n represents the average mean gray value of 30 individually measured nuclei in one embryo. n = 6 per time point, per condition. *, P < 0.001 by unpaired two-tailed t test.