FIGURE 4

FIGURE 4

A loss of Notch activity attenuates the muSC response to injury. Projections of confocal stacks of the myotome in uninjured (A,C,E,G) and injured (B,D,F,H) pax7a:eGFP larvae at 3 dpf (A–D) or 7 dpf (E–H). Animals were treated with 1% v/v DMSO (A,B,E,F) or 100 μM DAPT (C,D,G,H) prior to and after injury, fixed at 24 hpi and nuclei labeled with DAPI. There are more muSCs expressing eGFP (arrowheads) recruited to the injury (asterisk) in DMSO treated larvae (B’,F’) compared to DAPT treated larvae (D’,H’). Quantification of pax7a:egfp-expressing muSCs in uninjured and injured 3 and 7 dpf larvae treated with DMSO or DAPT. Tests for significant differences in muSC number due to injury, DAPT or age revealed that injury affected the number of muSCs present (p < 0.05), but DAPT treatment nor developmental stage did (p > 0.05, I). Pairwise comparisons revealed that injury-induced changes to the number of muSCs is attenuated by treatment with DAPT (p < 0.05, J,K). There is no significant difference in the number of muSCs in the myotome of uninjured 4 and 8 dpf larvae treated with DAPT (p > 0.05, L). Likewise, there is no difference of muSC number in the myotome of injured 4 and 8 dpf larvae treated with DAPT (p > 0.05, M). Significant differences were tested by 3-way ANOVA following transformation by ART (n = 47) and post hoc tests performed using a Dunn’s test with Benjamini and Hochberg correction. Error bars represent standard deviation, and values above comparison bars represent significance (p-values). Scale bars: 100 μm (A–H), 50 μm (A’–H’).