Fig. S6

Myocardial dnEct2 expression does not induce DNA damage or apoptosis, and exposure to dnEct2 during adulthood does not induce cardiomyocyte polyploidization, Related to Figure 3 and Figure 4. (A-D) Sections from hearts from the indicated cohorts, immunostained for γH2AX (to detect DNA damage), GFP and counterstained with DAPI. γH2AX signals are shown in bottom panels. Boxed regions are shown at higher magnifications (insets). Irradiated animals (B) serve as a positive control for the DNA damage response. Yellow arrowheads in insets indicate cardiomyocyte nuclei. (E-G) TUNEL staining in sections from hearts from the indicated cohorts, immunostained for GFP and counterstained with DAPI. TUNEL signal is shown in bottom panels. Section in (E) was incubated in DNAse I as a positive control for apoptosis. (H) External appearance of double-transgenic adult zebrafish, subjected to early recombination during embryogenesis, grown in the absence of polyploid-inducing heat-shock treatments and exposed to one week of daily heat-shock treatments during adulthood. (I,J) DNA content (I) and quantification of indicated cardiomyocyte populations (J) from (H). n=2839 total cardiomyocytes from 3 replicates, 3 ventricles per replicate. Scale bars: 50 μm (A-G, K), 5 mm (H).