Fig. EV3

Pre-existing pectoral fin myofibers are eliminated and replaced by a de novo source. (A) The palmuscle-Multi and the myofiber:iCre#2 transgenic constructs. (B) Timeline of the tracking scheme. (C, D) Long-term tracking of the Tg(palmuscle-Multi; myofiber:iCre#2) double transgenic line in different anatomical regions, including the pectoral fin region (C) and the craniofacial region (D). No leaky Cre activity was observed. (E) The mylpfa:Brainbow1.0 L and myofiber:iCre#2 transgenic constructs. (F) Timeline of the treatment and tracking scheme. (G) Long-term tracking of the Tg(mylpfa:Brainbow1.0 L; myofiber:iCre#2) double transgenic line showed no leaky Cre activity. (H) Long-term time-lapse imaging of the same myofibers at 14, 21, and 28 dpf. White arrows highlight ?disappearing myofibers?. White dashed lines (bottom right, G and H) outline the bottom pectoral fin myofiber compartment, which becomes less visible at 28 dpf due to tissue thickening. (I) Quantification of tagged myofiber numbers. (J) Cross-sectional view of the pectoral fin myofibers showing both top and bottom layers at 14, 21 and 28 dpf. (K, L) Quantification of myofiber numbers (K) and myofiber areas (L). The entire top layer of fin myofibers were included in the quantification. Data from biological replicates are shown as mean ± standard deviation (K) or violin plots (solid lines, median; dashed lines, quartiles; L). Significance was examined by two-tailed Student?s t-test (K) or two-tailed Mann?Whitney test (L). Percent differences and P values are shown above the horizontal lines for intergroup comparisons. n = number of animals (C, D, G, H, K) or myofibers (I, L). Scale bars, 50 µm (J) and 100 µm (C, D, G, H). dpf, days post-fertilization.