Fig. 1

Generation of Pax7-YFP knock-in mice. a Schematic diagrams showing the knock-in construct and knock-in allele. A targeting vector for generating a Pax7-YFP knock-in mouse line was constructed by inserting an EYFP sequence downstream of exon 9 of the Pax7 gene locus. b Genotype of Pax7-YFP knock-in mice was verified by a two-primer PCR strategy (wild-type = 134 bp, Pax7-EYFP = 2441 bp). Pax7^+/+, wild-type; Pax7^YFP/+, heterozygous Pax7^YFP/+; Pax7^YFP/YFP, homozygous Pax7^YFP/YFP. c Immunohistochemistry of YFP in the neural tube (NT) and somite region of a Pax7^YFP/YFP mouse embryo at E10.5, scale bar 50 μm. d YFP fluorescence signals in the dermomyotome (DM) region of a Pax7^YFP/YFP mouse embryo at E10.5, scale bar 50 μm. e Representative fluorescence images of YFP+ cells in soleus (Sol) and extensor digitorum longus (EDL) muscle tissues freshly isolated from Pax7^YFP/YFP mice, scale bar 50 μm. f Immunohistochemistry of YFP and laminin α2 in cryosections of TA muscle from adult Pax7^YFP/YFP mice. Arrows indicate YFP⁺ cells, scale bar 50 μm. g Immunohistochemistry showed that YFP+ cells were co-localized with PAX7+ satellite cells in transverse sections of TA muscle in Pax7^YFP/YFP mice. Arrows indicate YFP + PAX7+ satellite cells, scale bar 20 μm. h-j Immunostaining showed that YFP + PAX7+ satellite cells associated with individual myofibers freshly isolated from EDL muscle in Pax7^+/+, Pax7^YFP/+, and Pax7^YFP/YFP mice. Arrows indicate PAX7+ satellite cells. h The number of satellite cells per myofiber was quantified in (i). YFP+ cells totally overlapped PAX7+ satellite cells (j) (n = 3–5, > 20 myofibers per animal were counted), scale bar 20 μm. DAPI was used to visualize nuclear staining. Data represent means ± s.e.m. (one-way ANOVA followed by the Bonferroni post hoc test). NS non-significant