Fig. 2

Improved editing efficiency of DdCBE-NES in the presence of mitoTALEN in mice. a Base editing target for generating the m.G12918A mutation. The TALE binding sequences for the DdCBE are highlighted in green and for the mitoTALEN in orange. The mitoTALEN was designed to recognize a site with a single mismatch with the wild-type mtDNA sequence, as denoted with a lowercase letter. b Effect of mitoTALEN, used to eliminate wild-type mtDNA in mouse blastocysts, on the m.G12918A base editing efficiency. Targeted deep sequencing data were obtained from blastocysts that developed after microinjection of zygotes with mRNAs encoding the indicated constructs. Exact p-values are **0.0006 for DdCBE compared with DdCBE + mitoTALEN, **0.0022 for DdCBE-NES compared with DdCBE-NES + mitoTALEN, and *0.0467 for DdCBE compared with DdCBE-NES; n.s. is 0.3519. (N ≥ 3; n.s., not significant, *p < 0.05, **p < 0.01, and ***p < 0.001 using Student’s two-tailed t-test). c Images of a mouse harboring the m.G12918A point mutation (ptpup-18) with a wild-type C57BL/6 mouse. d Transmission electron micrographs of the mitochondria in the kidney and brown adipose tissue from wild-type and ptpup-18 mice. e Immunohistochemistry images of the brain sections from wild-type and m.G12918A mutant mice. Brain sections, stained with anti-NeuN antibody visualized with DAB (3,3′-diaminobenzidine), from the forebrain and midbrain regions of brains from a wild-type mouse, pt119 (a littermate of the pt121 mouse with normal behavior), and the pt121 mouse with a hunchback phenotype. The arrow on the pt121 forebrain section indicates one of the enlarged lateral ventricles, and the arrow on the pt121 midbrain section shows the asymmetric hippocampus in this mouse harboring the m.G12918A mutation