Table 3. CRISPR/Cas9-mediated gene editing at the Tet2 Locus in C57BL/6NJ embryos delivered by electroporation.

Group	Cas9/sgRNA conc. (ng/μl)	Embryos electroporated	Embryos transferred	Mice born	Mutant mice	Efficiency (%)
1	600/300	20	18	7	2	29
2	600/300	20	19	6	6	100
3	0/0	20	20	11	NA	NA

Zygotes were derived from C57BL/6NJ and treated with acidic Tyrode’s solution for 10 sec before electroporation. A total of 20 embryos for each concentration were electroporated in a cuvette of 1-mm gap size and in 20 μl of TE/Opti-MEM at 1:1 volume ratio. Following electroporation, the embryos were transferred to 100 μl of M2 media and transferred into pseudopregnent female mice. For each live born mouse, PCR product at the target site was amplified from genomic DNA isolated from tail biopsies and analyzed by RFLP and Sanger sequencing. conc., concentration.