Temporal resolution of in vivo electroporation. (A–C) Images of embryos 24 h after electroporation for embryos electroporated at 24 hpf (A), 48 hpf (B), and 96 hpf (C). Voltages used were 75, 80, and 95 V, respectively. Scale bars represent 100 μm top panels and 50 μm bottom panels. To characterize the temporal resolution of in vivo electroporation, embryos were electroporated at 24, 48, or 96 hpf. Twenty-four hours after electroporation the embryos were screened for expression of GFP and for viability. Voltage was varied to assess the efficiency of electroporation at that stage of development. (D, F, H) The percentage of embryos expressing GFP was determined for each voltage. Embryos were considered positive if at least 10 cells with neuronal morphology were expressing GFP; however, the vast majority of positive embryos had 100-plus cells showing fluorescence. (E, G, I) Viability was assessed by embryo morphology and the presence of a strong heartbeat. Gray boxes indicate a range of voltages for which there is high expression and very high viability. Data points are color-coded to investigator to further demonstrate the robustness of the technique (blue: S.A.; red: S.K.). Common data symbols (squares/circles and closed/open) represent all of the data points for one experiment.