Fig. 1

Oncogenic RAS induces proliferation of neural progenitor cells, clonal expansion and reduced survival. (A,B) Schematic representation of tumour induction through (A) the cross between zebrafish lines carrying the indicated transgenes or (B) the injection of the oncogenic construct (green) into zic:Gal4 embryos to express UAS:GFP-HRAS^V12 specifically in the brain. (C,D) Dorsal view of representative 3 dpf images of larvae showing the telencephalon in a control larva (C, zic:Gal4, mCherry expression) compared with that of an oncogenic larva (D, zic:RAS_germline, mCherry expression; D′, zic:RAS_germline, UAS:GFP-HRAS^V12 expression), white dotted lines mark the eyes. (E) Quantification of brain size reveals a doubling in size of the zic:RAS_germline-expressing tissue. (F) Counting of BrdU-positive cells in the telencephalon of 3 dpf larvae reveals doubling in the number of proliferating cells in zic:RAS_germline versus zic:Gal4 controls. (G-G″) Dorsal view of three 1 dpf zic:RAS_somatic larvae showing individual clones expressing UAS:GFP-HRAS^V12. (H-H″′) Lateral bright-field and coronal confocal images of the telencephalon of three live zic:RAS_somatic larvae (plane of focus indicated by red lines in H) at 1 dpf, 3 dpf and 5 dpf revealing clonal expansion of oncogene-expressing cells in the same larvae from 1 to 5 dpf. White dotted lines mark the outline of the brain. (I) Survival curve of zic:RAS_somatic larvae (green dashed line; n=166) compared with zic:Gal4 controls (black line, black asterisk; n =105) and zic:RAS_germline larvae (green solid line, green asterisk; n =255). Data are represented as mean±s.d. **P<0.03, ***P<0.001. Scale bars: 500 µm in C,D; 500 µm in H; 50 µm in H′.