Fig. 6

Wnt/β-catenin and HH signaling are necessary for normal scale regeneration.

(A) Adult scales labelled with sp7:EGFP (yellow), were removed from the caudal peduncle (0 d post-pluck). One day following surgery (1 d post-pluck) patterned Wnt/β-catenin signaling activity was detected, as revealed by 7xTCF:mCherry (cyan, arrowheads). After two days (2 d post-pluck), all removed scales had started to regenerate; n = 8. (B) Scale regeneration occurred normally in heat-shocked controls (n = 7), whereas hs:dkk1 induction delayed scale regeneration (n = 10). Asterisks (*) mark ontogenic scales not plucked. (C) Heat-shocked controls regenerated a significantly higher proportion of scales two days after scale removal (2dpp) then hs:dkk1 fish (p=0.0004). Three days after scale removal (three dpp), all heat-shocked controls had regenerated their full complement of scales whereas hs:dkk1 fish regenerated significantly fewer scales (p=0.0007). (D) Regenerating scales grew more quickly in heat-shocked controls than in hs:dkk1 fish (p=0.003). Plots indicate means ± SD. (E) In heat-shocked controls, epidermis (cldnb:EGFP, green) folded around regenerated scale plates (ARS; magenta) within ten days of scale removal (n = 6), whereas HH repression (hs:gli2-DR) prevented epidermal folding (n = 8). Asterisks (*) mark ontogenic scales not plucked. Scale bars, 500 µm (A, B, E); 100 µm (E, orthogonal views).