Fig. S6

Quantification of sequential muscle fusion of col1a2+ sibling cells. col1a2Kaede; ubi:Zebrabow embryos were injured at 48 hpf, and imaged from 32 to 52 hpi. The same experiment is also shown in Figure 6E and Movie 6. (A) Image quantification. Change in fluorescent intensity at each time point was generated by subtracting the fluorescent intensity of corresponding channels at the previous time point (5 minutes earlier). Note that negative pixel values after image processing were set to zero. The muscle fiber that col1a2+ sibling cells fused to is indicated by dotted lines. The increase of Kaede intensity but not the RFP signal in the muscle fiber can be observed at 11:15 (1st fusion event) and 16:00 (2nd fusion event). (B) Quantification of fluorescence change before and after cell fusions. Small ROIs within the outlined muscle fiber were measured for fluorescent intensity at different time points (n = 27 for the 1st fusion event and n = 26 for the 2nd fusion event). Change in fluorescent intensity for each ROI in each channel was calculated and plotted for each time point. For example, change in fluorescent intensity for a given ROI at the 1st fusion (11:15) was generated by subtracting the fluorescent intensity at 11:10 from the intensity at 11:15. Significant increase in Kaede intensity but not the RFP signal in the muscle fiber can be observed at 11:15 (1st fusion event) and 16:00 (2nd fusion event), suggesting fusion events between a Kaede+ MPC and a muscle fiber. All data are plotted with mean ± SEM indicated. Statistics: Mann-Whitney U test. Asterisks representation: p-value < 0.001 (***) and p-value < 0.0001 (****). Scale bar: 50 μm.