Extended Data Fig. 5: GFP-to-BFP knock-in conversion in chicken ESCs.

a, Schematic illustrating the design of the GFP-to-BFP conversion. The purple line underscores the GFP gRNA used in this assay. Nucleotide changes introduced by the ssODN donor are highlighted in red. The exact sequences of the GFP gRNA and ssODN are provided in Supplementary Table 5. b, Representative FACS plots showing the percentages of GFP/BFP-positive cells in control and engineered samples. Note that both samples contain feeder cells, which were GFP/BFP-negative. c, Representative images of GFP control cells and engineered cells after cell sorting and clonal expansion. n = 3 independent experiments. Scale bars, 50 μm. d, Sanger sequencing traces of genomic DNA amplicons from GFP control and engineered clonal lines. Nucleotide changes are marked in red. The yellow box highlights an extra C nucleotide insertion in one allele of BFP⁺/GFP⁻ clone 2. The purple line and orange lines mark the GFP gRNA sequence and PAM site, respectively. The dashed line indicates the Cas9 cutting site.