Fig. 6 The flo mutation activates the DNA damage response.
(A–C) Acridine orange staining showing apoptosis in the 50 hpf flo retina that is rescued by the tp53 morpholino (mo) knockdown. (D) Histological cross section showing rescue of flo retinal architecture defects by tp53 knockdown [compare (F) with Figure 1G and 1H]. (E) Intestinal defects persist in flo/tp53 double mutants. Arrow, thin intestinal wall; Arrowhead, apoptotic cells in the intestinal lumen. (F) Western blot showing elevated levels of phospho-Chk2 (Serine 33) in the intestine of flo larvae, compared with sibling wild type larvae, but not slim jim larvae (I). (G) Western blot showing comparable levels of phospho-Chk1 (Ser 345) in flo and sibling wild type larvae, before and after γ-radiation (30 Gy) and treatment with hydroxyurea (HU). (H) Western blot showing enhanced phospho-Chk2 activation in the intestine of flo and wild type larvae following γ-radiation (30 Gy). (I) γH2AX is not detected in the flo or wild type intestine (75 hpf), but is detected at this stage following γ-irradiation (30 Gy) or hydroxyurea treatment (HU).