Comparison of LucR and LucF+ monocistronic versus bicistronic vector expression after electrotransfer in mouse muscle. Mice were electrotransferred with either 30 μg of monocistronic plasmid encoding LucR or LucF+ (Mono LucR or Mono LucF, respectively), or with a mixture (30 μg + 30 μg) of the two plasmids (Mono LucR + LucF), or with 30 μg of the bicistronic plasmid containing the FGF-1 IRES (IRES FGF1A). LucR and LucF+ activities were measured from 5 to 21 days after electrotransfer. A. Detection of the LucF+ signal with the CCD camera. LucF+ activity was detected at days 5, 15 and 21 in live animals as in Figure 3. Images are shown in pseudocolors. Time of exposure and a pseudocolor scale are represented. B. LucF+ signal quantification. On the top panel, the values detected with the CCD camera for each time point are expressed in mean grey level/second/ROI (mean ± sem, n = 6). The bottom panel shows the LucF+ relative quantification at day 5 (D5), day 15 (D15) and day 21 (D21) for each vector. C. Luciferase activities quantification at day 5 and 21 after electrotransfer. Two groups of mice were sacrificed at day 5 and 21, and muscles lysates were used for luciferase activity quantification using the luminometer. LucR (top panel) and LucF+ (bottom panel) are expressed in RLU/μg total proteins (mean ± sem, n = 6). D. Bioluminescent signal relative quantification. Luciferase relative quantification was obtained for each vector at day 5 (D5) and day 21 (D21).