Fig. 3.

foxm1⁺ cardiomyocytes are localized near nrg1⁺ cells and are epistatic to the Mapk regulator, dusp6. (A,B) In situ hybridization showing nrg1 (green) and foxm1 (red) in WT 7 dpa hearts. (C) foxm1⁺ cardiomyocytes were proximal to nrg1⁺ non-myocytes. A total of 21 nrg1⁺ cells were scored in WT 7 dpa hearts (n=5). Box plots show minimum to maximum. The whiskers show the minimum and up to the maximum value, with the middle line representing the median. (D-G) dusp6^m/+;foxm1^m/+ fish were bred to generate double mutants to assess their epistatic relationship. dusp6^m/m hearts (E; n=7), dusp6^m/+;foxm1^m/+ (D; n=6), dusp6^m/m;foxm1^m/+ hearts (F; n=6) and dusp6^m/m;foxm1^m/m hearts (G; n=6) were stained with Mef2 (green) and Pcna (red). White dotted lines represent the injury border. White arrowheads indicate representative Pcna⁺/Mef2⁺ cardiomyocytes. (H) Graph showing CM proliferation index. Each point on the truncated violin plot represents an individual heart and these data represent three biological replicates. The middle line represents the median. (I) In situ hybridization for foxm1 was performed in WT (n=3) vehicle treated with 50% DMSO and erbb2^+/m (n=2) hearts treated with AG1478. The number of foxm1⁺ cardiomyocytes was quantified in control and erbb2^+/m-treated hearts. Each point on the truncated violin plot represents an individual heart and is averaged from four sections. The middle line represents the median. Statistical significance was calculated using two-tailed, unpaired Student's t-test and one-way ANOVA multiple comparison test. ***P=0.0006 (two-tailed, unpaired Student's t-test, C); **P=0.0022, ****P<0.0001 (one-way ANOVA, H); *P=0.0416 (two-tailed, unpaired Student's t-test, I). Scale bars: 50 μm.