klf2mutants result in compensation of homologue expression, blunted Notch signaling activation and reduced ventricle regeneration. (A and B) Schematic diagrams of the zebrafish klf2a and klf2b loci with the sgRNA target site sequence (red arrowheads). (C, D) Functional domain diagrams of wildtype Klf2a or Klf2b and predicted truncated protein in corresponding mutants. (E–L) Whole-mount in situ hybridizations showing klf2a expression pattern in the control and ablated hearts of wildtype, klf2a−/− mutants, klf2b−/− mutants and klf2−/− double mutants at 24 hpt. (M) Quantification of the fold change of klf2a expression in wildtype and klf2 mutant larvae at 4 dpf by real time PCR. 4 independent experiments. Mean + s.e.m. ANOVA analysis, *P < 0.05, **P < 0.01, ***P < 0.001. (N–U) Whole-mount in situ hybridizations showing klf2b expression pattern in the control and ablated hearts of wildtype, klf2a−/− mutants, klf2b−/− mutants and klf2−/− double mutants at 24 hpt. (V) Quantification of the fold change of klf2b expression in wildtype and klf2 mutant larvae at 4 dpf by real time PCR. 4 independent experiments. Mean + s.e.m. ANOVA analysis, **P < 0.01. (W) Quantification of the heart recovery rate (black bars) in ablated wildtype and klf2 mutants at 4 dpt. The number of larvae analyzed for each condition is indicated. Binomial test (versus WT), ****P < 0.0001. (X–M’) Confocal stack projections of ablated Tg(vmhc:mCherry-NTR; tp1:d2GFP) hearts showing Notch signaling pattern in wildtype (X–A’), klf2a−/− mutants (B’–E’), klf2b−/− mutants (F’–I’) and klf2−/− double mutants (J’–M’) at 12, 24, 36, 48 hpt. (N’–U’) Whole-mount in situ hybridizations indicated notch1b upregulation as in ablated wildtype hearts (N’, O’) was blocked in klf2a−/− mutant hearts (P’, Q’), klf2b−/− mutant hearts (R’, S’) and klf2−/− double mutant hearts (T’, U’) at 24 hpt. Scale bars, 50 µm. hpt, hours post treatment. Dashed lines outline the hearts. Numbers indicate the ratio of representative staining observed
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