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Fig. 6.
Macrophages are required for enhanced cardiomyocyte number expansion following cardiac injury and transient AT7519 treatment. (A) Restriction enzyme digest gel displaying irf8 zebrafish genotypes. Hyperladder (HL) band and individual genotype bands (in order: irf8+/+, irf8+/− and irf8−/−) are indicated. (B) Brightfield images of 3 dpf larval heads stained with Neutral Red showing macrophages/microglia in the brain of irf8+/+ larvae but not in irf8−/− larvae, with irf8−/− larvae devoid of all macrophages/microglia. Arrowheads indicate the presence of macrophages/microglia; inset shows a higher magnification of the boxed area. Scale bars: 500 μm. (C) LSFM images of irf8+/+ and irf8−/− Tg(myl7:h2b-GFP) larvae displaying ventricular cardiomyocytes at 48 hpi following transient treatment with 0.1% DMSO vehicle (top) or 50 μM AT7519 (bottom). Scale bars: 50 μm. (D) Number of ventricular cardiomyocytes at 48 hpi following transient treatment with 0.1% DMSO vehicle or 50 μM AT7519 in irf8+/+ and irf8−/− larvae. Error bars represent s.d., n=25 larvae, experimental n=3. *P<0.05 (one-way ANOVA and Tukey post-hoc test for comparisons between DMSO vehicle or AT7519 treatment groups). ns, non-significant.