Fig. 5

(A) In uninjured fins, H₂O₂ was always detectable with pentafluorobenzenesulfonyl fluorescein (see Methods) in a few cells near the notochord (arrowhead) but was not detectable in fin tissue. Fin amputation (arrows) produced high levels of H₂O₂ in wound marginal cells at 30 min post-amputation. In contrast, H₂O₂ levels were either undetectable or very low in duox1 morphants at 30 mpamp. (B, C) Ablating multiple keratinocytes produced hydrogen peroxide (H₂O₂). Time-lapse sequences from 78–90 hpf. The rightmost panel shows axon tip trajectories (red) over the course of the time-lapse and denervated territory (shaded areas). (B) Ablation of one or two keratinocytes (circles) did not produce sufficient H₂O₂ to be detected by the H₂O₂ sensor pentafluorobenzenesulfonyl fluorescein and did not promote axon regeneration of a nearby severed axon. (C) Ablating more (e3) keratinocytes (circles) induced H₂O₂ production around the wound margin, as detected with the H₂O₂ sensor, and improved regeneration of a nearby axotomized arbor, which grew into denervated territory (shaded area, trajectories). mpamp, minutes post amputation.