Abstract
Creating genetically modified (GM) animals using CRISPR/Cas mediated through the electroporation of two-cell stage embryos, rather than fertilized eggs, holds considerable potential. The full potential of genome editing using two-cell stage embryos is only beginning to be explored. We developed an improved electroporation method to prevent blastomere fusion in two-cell-stage embryos, enabling efficient genome editing. Using this method, we demonstrated that the indel mutation rates and ssODN knock-in (KI) efficiencies in two-cell-stage embryos are comparable to those in fertilized eggs, with a tendency for higher efficiency in long DNA KI. This study highlights the potential value of two-cell-stage embryos and provides enhanced animal model production opportunities. Furthermore, realizing genome editing in two-cell-stage embryos extends the editing timeframe from fertilized egg to two-cell-stage embryo, offering promising avenues for future research in embryo genome editing techniques.