Figure 4. The pylorus proliferates in response to damage.

In A-H) adults of the genotype UAS hid rpr ; Gal80^ts ; byn-GAL4 UAS-GFP were shifted to 30 °C to induce damage in the hindgut. A) Punctate nuclei of dying pyloric cells (arrows) 2 days after damage induction. B) The number of BrdU-labeled adult hindgut cells (average +/− standard deviation) is greatly increased following damage induction (+), relative to controls lacking hid and rpr expression (−). Note: A Tub-GAL4 FLP-out system was substituted for byn-GAL4 in one experiment (see I). C). BrdU incorporation occurs preferentially in the adult pyloric Wg ring (bracket) one day after damage induction. D) BrdU incorporation in the adult pylorus 2 days after damage induction is seen both in the Wg ring (bracket) and more posteriorly. E) Adult pyloric cells shifted to the non-permissive temperature and labeled with BrdU for one day (as in C) were examined after 4 additional days at 18 °C. Labeled cells are now seen throughout the pylorus. Bracket = Wg ring. F) The mean position of BrdU-labeled cells after 1 day of damage (D1, see panel C) and after 5 days (D5, see panel E) demonstrates cell movement. G) Cells positive for phosphohistone H3 (PH3) (average +/− standard deviation) are greatly increased in adult hindguts following damage induction (+), relative to controls lacking hid and rpr expression (−). H) Cell division marked by PH3 (green) two days after damage induction is confined to the Wg ring (bracket). I) BrdU incorporation 1 day after the induction of FLP-out clones marked with GFP (pink) and expressing hid and rpr (full genotype indicated on panel). BrdU incorporation (green) is observed within the Wg ring (bracket) in unrecombined cells adjacent to GFP-expressing cells (see inset). All images- anterior to the left. Dashed box = region shown in inset. In D, E and H, byn = GFP (purple); in I, GFP = UAS hid,rpr positive. Pros=Prospero, Wg = Wingless. Scale bars- white=25μm, red=12.5μm.