Fig. 2

Drastic increase in myofiber number and volume enables rapid organismic growth. (A) Timeline of larval growth manipulation and tracking scheme. SG, slow growth. FG, fast growth. (B) Representative cross-sectional view of Myotome #12 under either the SG or the FG condition at 10 and 14 dpf. Yellow dashed lines mark the boundary of a myotome. (C–G) Larval growth under either the SG and the FG condition as determined by standard length (C), trunk surface area (D), myotome number (E), total myofiber number (F), and myotome volume (G). (H) 3D surface rendering of all myofibers in Myotome #12. Pseudo-colored images highlighting myofiber volume were generated by Imaris. (I–K) Quantitative changes in myofiber volume (I), myotome composition (J), and percentage of the hyper-nucleated myofibers (K). Data from biological replicates are shown as mean ± standard deviation (C–G, K) or violin plots (solid lines, median; dashed lines, quartiles; (I). Significance was examined either by two-tailed Student’s t-test (C, D, F, G, K) or two-tailed Mann–Whitney test (E, I). Percent differences and P values are shown above the horizontal lines for intergroup comparisons. n = number of animals (C–G, K) or myofibers (I, J). Scale bar, 50 µm (B). dpf, days post-fertilization. Source data are available online for this figure.