Fig. 8. Ectopic expression of porcupine in the chick neural tube shortens the BAT-gal reporter gradient. The BAT-gal reporter construct was co-electroporated into chick neural tubes along with either pCIG (control), Wnt1, Wnt3a, mPorcD or mPorcD(H341Q) constructs. GFP-positive embryos were harvested for analysis 24 hours post-electroporation. Embryos were fixed, cryosectioned and immunostained with antibodies against ß-galactosidase. Sections were imaged with confocal microscopy. Merged images of the GFP and ß-galactosidase expression are shown above, separate channels below. The vertical green line demarcates the distance of GFP expression from the dorsal-most extent of the neural tube; a red line demarcates the distance of BAT-gal expression from the dorsal neural tube. A graphic representation of the ratio of the BAT-gal distance divided by the GFP distance is shown. N, number of embryos analyzed; n, number of sections analyzed. Error bars indicate standard error.