Figure 3

Pax7 represses Meis2 and efnb1 in the mesencephalic vesicle. (A-B") Meis2 expression in HH15 chick embryos electroporated with 2 μg/μl of a control vector carrying only GFP (A) or 2 μg/μl pMES-Pax7 (B, B") into the right wall of the mesencephalic vesicle. The insert in (A) shows a higher magnification and continuous expression of Meis2 in the control embryo. (B') is a higher magnification of the boxed area in (B). Arrowheads point to patches of cells with reduced Meis2 transcripts. In (B") the GFP fluorescence of the specimen shown in (B and B') is superimposed to visualize the extent of Pax7/GFP transfection. (C-D') efnb1 expression in a HH15 chick embryo transfected with a control vector (C) or with pMES-Pax7 (D, D') under identical experimental conditions. (D') is a higher magnification of (D). (E) Quantification of the results: percent specimens with reduced (red bars) and unaltered (blue bars) Meis2 or efnb1 expression following targeted electroporation of pMES-Pax7.