Fig. 3

Neutrophil-Delivered Myeloperoxidase Is Required for the Initial Decline in Wound Margin H₂O₂ Concentrations(A) (i) Mean HyPer ratios reflecting the wound zone [H₂O₂] data for injured and uninjured drf embryos. Note the sustained, elevated HyPer ratio/[H₂O₂] in mpx-deficient drf mutants. These drf data are directly comparable with data of Figure 1A and share its WT control group. Inset (ii) shows the individual median HyPer data and p value compared to WT (natural permutation test). The n values are as follows (embryos/independent days/scans): injured drf, 6/5/6; uninjured drf, 4/1/4. (iii) Representative HyPer heat maps depicting [H₂O₂] across the wounded tail fin of an mpx-deficient drf embryo with overlaid transmission (Trans) and DsRED2 images demonstrating the proximity of neutrophils to the wound margin. Scale bar represents 200 μm. Stills are from Movie S1 at same time points as in Figure 1B.(B) (i) Transplantation strategy to generate HyPer-mRNA-loaded, Mpx-deficient, drf embryos selectively populated with DsRED2-expressing WT neutrophils. (ii) A successful transplant outcome. Brightfield image of 3 dpf embryo with superimposed green and red fluorescence images, showing a single residual recipient-derived EGFP-expressing neutrophil (green arrow) and scattered DsRED2-expressing donor neutrophils (red arrows).(C) (i) Mean HyPer ratios reflecting the wound zone [H₂O₂] profile of drf embryos carrying WT neutrophils, which arrive (pink) or do not arrive (orange) at the wound. WT neutrophil arrival recapitulates the WT HyPer ratio profile; WT cell nonarrival serves as a negative control demonstrating the sustained [H₂O₂] elevation of a nonrescued Mpx-deficient drf profile. Inset (ii) shows the individual median HyPer data. The n values are as follows (embryos/independent days/scans): WT cells arrived, 3/3/3;WT cell did not arrive, 3/3/3.(D) HyPer heat maps depicting [H₂O₂] across the wounded tail fin of a transplanted drf embryo with arriving WT cells, demonstrating lower [H₂O₂] levels in the tail half where WT DsRED2-expressing cells arrive. Overlaid transmission (Trans) and DsRED2 images demonstrate the proximity of Tg(lyz:DsRED2) neutrophils to the wound margin. Scale bar (applies to all panels) represents 200 μm.