Movie 5

Generation of new muscle fibers by cell fusion. col1a2^NTR-mCherry; α-actin:GFP embryos were injured at 79 hpf and imaged from 24 to 36 hpi. The red channel (col1a2^NTR-mCherry), the green channel (α-actin:GFP), and the merged images are shown with time stamps indicated in the hh:mm format. A mCherry⁺ MPC (arrows) near the injury site elongated and fused with a neighboring muscle fiber between 07:07 and 07:14. The fusion event was evident by the spreading of the mCherry signal in the muscle fiber and the mCherry signal in the nucleus (arrowheads) remained visible until the end of the movie at 12:15. A total of 23 fusion events were observed in movies from 12 embryos. Scale bar: 50 μm.