Fig. 1: Pulse of premature shh during early fin fold development disrupts adult caudal fin shape.

(A-B) Caudal fins of control zebrafish and (C-D) transgenic zebrafish subjected to transient shh overexpression 2 dpf (shh pulse). (B and D) are cleared and stained caudal fins from juvenile zebrafish. Dashed outlines indicate the overall shape of the fins. Arrow indicates the location of the hypural diastema separating the dorsal from ventral lobes in B; asterisk indicates the absence of the diastema in (D). (E) The inheritance of the hsp70l:shha-eGFP transgene and the activation of the promoter by heat shock are both necessary in order to induce the truncate fin phenotype. Significance determined by ANOVA followed by Tukey’s post hoc test. An embryonic shh pulse (F) increases the number and variance of principal fin rays and (G) causes a loss of the hypural diastema. Significance determined using Welch’s two-sample T-tests. (H-J) Treatments with the Smoothened inhibitor BMS-833923 after shh pulse can partially rescue both (I) forked fin shape and (J) horizontal stripes of pigmentation. Significance determined by ANOVA followed by Tukey’s post hoc test. Scale bars, 1 mm.