Transcriptional changes after thoracotomy suggest the activation of cardioprotective and EMT genes in the epicardium. a Experimental design. High throughput sequencing (HTPS) of ventricles collected at 0 (control), 1 and 7 days post-thoracotomy (dpt). For each group, RNA was extracted from a pool of 8 ventricles. The encircled numbers indicate differentially expressed genes at each time point. The middle number depicts differentially expressed genes common for both time points. b Heat-map representation of the common 53 differentially expressed genes at 1 and 7 dpt. Genes are grouped according to biological function. Fold changes are represented in log2 scale (blue: log2 < 0; red: log2 > 0). c In-situhybridization of ventricular transversal sections reveals upregulation of several candidate genes (purple) in the epicardial and sub-epicardial region at 7 dpt, compared to control hearts at 0 dpt. The frames indicate the part of the section that is magnified on the right side of each image. n ≥ 3 hearts. Scale bar for the whole section, 100 μm; for the magnified area, 50 μm. d Immunofluorescence staining of ventricular sections of transgenic fish ET27:EGFP(red) with antibodies against cardiac Tropomyosin (TMP, blue) and ColXII (green). At 0 dpt, ET27:EGFP + cells and ColXII are confined to the epicardium. At 7 dpt, ET27:EGFP + cells and ColXII expand and infiltrate the myocardium. Arrows indicate intramyocardial ET27:EGFP + cells. Scale bar, 50 μm. e Quantification of intramyocardial ET27:EGFP + area per ventricular section area. Superficial epicardial ET27 + cells were not included in measurements. n ≥ 3 hearts, 3 sections per heart each. *P < 0.05 with student’s t-test. Error bars represent standard error of the mean (s.e.m.) (This applies to the all subsequent figures)
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