Fig. 3

In vivo test of selected neuron-specific promoters. A Schematics of the vector constructs and injections. The blue dot indicates the injection region. FB, forebrain; MB, midbrain; BS, brainstem; CB, cerebellum. B Promoter test with in ovo electroporation and surrogate culture. EGFP expression induced by four different promoters was analyzed in the embryonic brain on embryonic day 5 (E5). One day after electroporation, EGFP expression was observed by fluorescence microscopy in the injected region of the whole brain. The brain was paraffin-sectioned and stained with anti-EGFP antibody. The CMV promoter was used as positive control. The dotted box indicates the region of magnification image. Scale bar, 1 cm (embryos), 200 μm (whole brain), and 50 μm (sectioned brain). C Quantification of mean EGFP intensity per transfected brain cell by ImageJ. Significant differences between groups were determined using Student’s t-tests. ns, not significant; *p < 0.05; **p < 0.005; ***p < 0.0005. Embryos n = 5. D Promoter specificity test by in ovo electroporation of embryonic limbs. One day after electroporation, EGFP expression was observed by fluorescence microscopy in the injected region of limbs. Scale bar, 200 μm. Embryos n = 3