(A) The design of donor dsDNA templates and gRNA sequence for the construction of knock-in lines at the 3′ end of the krt4 locus. The nucleotide sequence in blue indicates gRNA, whereas the nucleotide sequence in red indicates the PAM sequence. The bottom panel shows the sequences of LHA and RHA. (B, C, D) Summary statistics of knock-in efficiency at the krt4 locus, including the percentage of injected F0 with fluorescence labelling on approximately one-third of their skin. (B, C, D) Knock-in mosaicism (B), the percentage of adult F0 giving rise to germline transmission (C), and the percentage of F1 siblings carrying the knock-in cassettes (D). (E, F, G, H) Representative confocal images of TgKI(krt4-p2A-mNeonGreen-t2A-iCre);Tg(ubiCSHm) at 1 dpf (E, E’, E’’), 2 dpf (F, F’, F”), 3 dpf (G, G’, G’’), and 6 dpf (H, H’, H’’). Skin and intestinal epithelial cells (at 3 and 6 dpf) were broadly recombined and labelled with H2BmCherry. (H) The white dashed lines outline the intestinal bulb (H, H’, H’’). Scale bars = 80 μm.