Fig. 4

Fast-twitch muscle fibers are impaired in ik KO embryos with downregulated myod1. a DIC confocal images of the skeletal muscle at 3 dpf WT and ik KO embryos. Scale bar = 20 μm. b Transverse sections of the skeletal muscle stained with anti-F310 (fast-twitch muscle fibers; left panel) and anti-F59 (slow-twitch muscle fibers; right panel) in 4 dpf WT and ik KO embryos. Scale bar = 20 μm. c Whole-mount immunostaining with anti-F310 (fast-twitch muscle fibers) of 4 dpf WT and ik KO embryos. Scale bar = 20 μm. d Whole-mount immunostaining with α-bungarotoxin (BTX) in 4 dpf WT and ik KO embryos. e Whole-mount in situ hybridization for myod1 mRNA in 20 somite stage (ss), and 2 dpf and 4 dpf WT and ik KO embryos. The red arrow indicates the position of signal myod1. Scale bar = 250 μm. f Relative myod1 mRNA levels in WT and ik KO embryos at 1.5 dpf and 4 dpf. The average of three independent experiments is shown with error bars. ***p < 0.001. g Whole-mount in situ hybridization for pax7a mRNA in WT and ik KO embryos at 22 hpf, 1.5 dpf, and 4 dpf. The red arrow indicates the position of signal pax7a. Scale bar = 250 μm. h Transverse section of whole-mount in situ hybridization for pax7a in 1.5 dpf WT and ik KO embryos. Scale bar = 25 μm. i Relative pax7a mRNA levels of 1.5 and 4 dpf WT and ik KO embryos. The average of three independent experiments is shown with error bars. *p < 0.05, **p < 0.01