Increased myocardial proliferation and protection in the runx1 mutant. (A-A″) Immunohistochemistry for PCNA and Mef2 on 3 dpci sections. An increased number of double-positive cells (arrowheads) seems present in the mutant compared with the wild-type wound border. (B) Quantification of PCNA-positive proliferating Mef2-positive myocardial cells after injury shows increased myocardial proliferation in the runx1 mutant at all time-points analysed. n≥4, two-way ANOVA with Sidak test. (C) Immunohistochemistry for MF20 with the nuclear marker Dapi. Arrowheads indicate the presence of MF20-positive myocardial cells in the wound in the mutant at both 3 and 7 dpci. (D) Quantification of the MF20-positive area in the wound on sections in the wild type and mutant shows increased presence of myocardial cells in the mutant. n=5, two-way ANOVA with Sidak test. *P<0.05, **P<0.01, ***P<0.001 and ****P<0.0001. Box extends from the 25th to 75th percentiles and whiskers indicate minimum to maximum with all data points shown. (E) Immunohistochemistry for Citrine and MF20. Arrowheads indicate the surviving MF20-positive cells in the mutant wound that are Runx1-Citrine negative. v, ventricle; w, wound. Scale bars: 100 µm.
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