Figure 6. Heat-shock induction of dn-fgfr1 reduces, but does not prevent, maxillary barbel regeneration.

White light (A) and fluorescent (B) illumination of an amputated hemizygous dn-fgfr1:EGFP caudal fin after 14 days of daily heat shock (> 37°C). The fin tissue shows inhibition of regeneration and enhanced green fluorescent protein (EGFP) expression. C) Comparison of maxillary barbel regeneration among heat-shocked wild type (red, wt), heat-shocked hemizygous (red, dn-fgfr1) and non-heat-shocked mixed zebrafish (black, wt & dn-fgfr1). In the absence of heat shock, wild type and hemizygous fish of this line cannot be distinguished and are therefore grouped together. Matched pairs of wild type (D) and hemizygous dn-fgfr1 (E) barbels after 14 days of daily heat shock. The transgenic animal in this example had strongly inhibited barbel regeneration. L = left, amputated barbel; R = right, unamputated barbel. F) Magnification of the regenerated barbel shown in E; although there is little regrowth, a small mesenchymal bulge (m) projects past the amputation plane. e = epithelial cap. G). The average amount of barbel regeneration observed in heat-shocked dn-fgfr1 animals (~0.5 mm). These barbels had more robust tissue outgrowths, including melanophores, a vascular loop, and abundant taste bud hillocks well past the amputation plane (H).