FIGURE 2

Wnt2bb mediates zebrafish heart regeneration. (A,B) Acid fuchsin orange G (AFOG) staining analyses reveal defective wound healing after ventricular resection in Tg(hsp70l:dn-wnt2bb) fish compared to that observed in the wild-type (ctrl) fish. Red arrow, fibrin; Blue, collagen; HS, heat shock of Tg(hsp70l:dn-wnt2bb) fish at 37°C for 1 h every 2 days for 30 days. (E) Bar charts showing the quantification of AFOG staining from (A,B). (C,D,F) AFOG staining and quantification reveals increased wound healing after ventricular resection in Tg(hsp70l:wnt2bb) fish compared to that observed in the wild-type (ctrl) fish. Red arrow, fibrin; Blue, collagen; HS, heat shock of Tg(hsp70l:wnt2bb) fish at 37°C for 1 h every 2 days for 21 days. Six hearts were assayed per group. (H–J) Confocal microscopy image analyses of PCNA⁺Mef2C⁺ cells (arrowheads) in heat-shocked Tg(hsp70l:dn-wnt2bb), Tg(hsp70l:wnt2bb) and wild-type (ctrl) fish at 7 dpa. Green, PCNA; Red, Mef2C. Boxes correspond to the magnified region. (K) Bar charts showing the quantification of PCNA-labeled CM proliferation index values for heat-shocked, injured wild-type (ctrl) and Tg(hsp70l:dn-wnt2bb) and Tg(hsp70l:wnt2bb) fish hearts. (G) Schematic of the experimental plan to analyze PCNA/Mef2c proliferation after apex amputation. The data are presented as the means ± SEM from 5 to 7 hearts for each group. The proliferation data were collected for 4–6 sections per heart and averaged to generate each data point. Error bars: ± 1 SD. Significance was determined using Student’s t-test: **P < 0.01, ****P < 0.0001. Brackets indicate the amputation area. Ctrl, control. Scale bar, 100μm.