Figure 5. BRV-B is a damage-responsive enhancer in multiple contexts.
(A-A’) egr-expressing clones activate BRV-B in some but not all regions of wing and eye discs. Heat-shock induced FLP-out clones expressing Gal4 (marked by RFP, red) were generated on day 4 and 5 of development in larvae bearing the BRV-B reporter. Clones were allowed to grow, and subsequently Gal4 was activated by inactivation of Gal80ts to express egr for 24 hr on day 8. GFP is expressed in and surrounding large dying clones (closed arrowheads) in wing discs (A) and eye/antennal discs (A’), but is absent from egr-expressing clones in various parts of each disc (open arrowheads), including the notum of the wing disc. (B) Disc from larva bearing the BRV-B reporter irradiated with 45 Gy on day 7, dissected after 16 hr and stained for cell death marker DCP-1 (gray), Wg (red) and GFP (green). The BRV-B reporter is strongly activated throughout the wing pouch and hinge (arrowhead), but not in the presumptive notum (open arrowhead). (C-D) Day 7 discs bearing the BRV-B reporter, physically cut (D, arrowhead indicates cut site) or left intact (C), and cultured in Schneider’s medium for 16 hr, followed by staining to detect GFP and Wg. Reporter activation is detected specifically along the cut site. (E-E’) Confocal sections through midguts of adult flies bearing the BRV-B reporter following 2 days of feeding 5% dextran solution as control animals, (E) or gut-damaging 5% DSS solution (E’). Guts were stained with anti-Delta (red) to show the intestinal stem cell (ISC) population, and GFP to detect reporter activity. Damaged gut tissue in DSS fed animals increases ISC number. Strong induction of the BRV-B reporter (green) is observed but not in the population that expresses Delta.
Figure 5—figure supplement 1. The BRV-B enhancer reporter is activated by genetic ablation in different tissues.
