Fig. 7

Fig. 7 Mosaic EfnB2a overexpression in the neural keel causes widespread cell sorting and duplication of the neuraxis. Dorsal views of 18–20 hpf embryos injected with heat-shock (HS)-GFP (A) or HS-EfnB2a DNA constructs (B–F) as indicated. Anterior is to the left. White circles indicate the position of the otic vesicle. (A) pHS-GFP-injected embryo coinjected with EfnB2a MO, and heat shocked at 10 hpf. GFP+ cells are symmetrically distributed on both sides of the neuroepithelium (N = 12/12). (B) pHS-EfnB2a-HS-GFP injected embryo coinjected with EfnB2a MO, heat shocked at 10 hpf and stained with α-EphA4 to detect r3, r5 (red). r4 is indicated with a white bracket. EfnB2a+/GFP+ cells (green) are distributed asymmetrically throughout the hindbrain, including in r4 (N = 16/27). (C–F) Embryos injected with the indicated HS constructs, with or without EfnB2a MO, heat shocked at the timepoint indicated on the far right and stained with α-aPKC. Left panel: aPKC expression alone; right panel: merged image showing distribution of EfnB2a+/GFP+ cells (green) and aPKC expression (red). (C, D) Embryo injected with pHS-EfnB2a-HS-GFP in the absence or presence of coinjected EfnB2a MO, heat shocked at 10 hpf. aPKC expression in two parallel stripes reveals partial duplication of the neuraxis (N = 7/14, and 9/14, respectively). (E) Embryo injected with the HS-EfnB2a-ΔC allele and EfnB2a MO, heat shocked at 12 hpf also shows neuraxis duplication (N = 9/20). A similar phenotype is observed when embryos are injected with the WT EfnB2a allele HS construct, in the absence or presence of EfnB2a MO, and heat shocked at 12 hpf (data not shown; N = 3/7, and 5/8, respectively). (F) Embryo co-injected with pHS-EFnB2a-HS-GFP and EfnB2a MO, then heat shocked at 16 hpf. EfnB2a-expressing cells contribute homogeneously to the epithelium and no duplication of the neuroepithelium has occurred (N = 14/14). Immuno-staining confirms that EfnB2a expression is still ectopically induced in embryos heat shocked at 16 hpf (data not shown; N = 7/7). Scale bar: 50 μm.