Figure 4.

Adult gut phenotypes in Hand¹⁷³ mutants. A) Schematic diagram of a wildtype adult gut from the proventriculus to the rectum; the peritrophic membrane tubule located within the lumen of the mid- and hindgut is shown in gray and the Malpighian tubules have been omitted. p, proventriculus; am, anterior midgut; mm, mid-midgut; pm, posterior midgut; h, hindgut; r, rectum. The crop is shown in normal (solid line) and distended food storage (dashed line) states. The adult guts in panels B, G–K were from adult flies fed with yeast mixed with red dye, which allows the unambiguous identification of ingested food within the gut. The foregut (anterior to the proventriculus) and the Malpighian tubules have been removed. B) Side-by-side comparison of the dissected guts of a 4.5 day-old wildtype (left) and Hand¹⁷³ mutant (right) adult with a weak phenotype. C–F) Phalloidin staining (green) of the anterior midgut of a wildtype adult gut (C,D) and the anterior midgut bulge of the Hand¹⁷³ mutant adult gut (E,F); panels C and F are blow-ups of D and E, respectively. G,H,I) Transverse sections through the posterior midgut of a wildtype adult gut (G), and a ruptured anterior midgut bulge (H) and mid-midgut (I) of Hand¹⁷³ mutant adult gut. Note the red yeast contained within the peritrophic membrane tubule of the wildtype adult gut (G). Asterisks indicate unidentified tissue attached externally to the Hand¹⁷³ mutant adult gut and dashed lines show the outer surface of the mutant gut tubes. Gut lumen in (I) is almost completely obstructed. J) Dissected 3 day-old Hand¹⁷³ mutant adult with a strong phenotype, showing numerous ectopic peritrophic membrane tubule loops (left). The gut with the anterior midgut bulge is positioned to right of the carcass. Note that the crop is distended with red yeast, which is not found elsewhere in the gut proper. Anterior is up. K) Close-up of the midgut in panel J. Note the numerous peritrophic membrane tubule loops (arrowheads) exiting a single orifice (arrow) on one side of the anterior midgut bulge, which are filled with a white non-food material in which bits of red yeast are interspersed.