Fig. 9

Effect of cyclopamine and forskolin on slow muscle development and Ca²⁺ signaling in the trunk. (Ai to Di) Representative bright-field images of embryos at 24 hpf that were either (Ai) untreated (controls), or else that were treated from 5.5 hpf with (Bi) 2% DMSO (DMSO-control), (Ci) 0.1 mM cyclopamine or (Di) 0.15 mM forskolin (n=4 for each of the untreated and drug-treated embryos). (Aii-Dii) The somites of the embryos shown in (Ai-Di), respectively, are shown at higher magnification. (Aiii-Diii) Projected stacks of confocal images through the trunk (at the position of somite 8; S8) of embryos treated as described for (Ai-Di), respectively, prior to fixation at 24 hpf and then the SMCs labeled by immunohistochemistry with the F59 myosin heavy chain antibody. Arrowheads in (Diii) indicate the few SMCs that still formed in the forskolin-treated embryos. Ant. and Pos. are anterior and posterior, respectively. Scale bars are (Ai-Di) 250 μm, (Aii-Dii) 50 μm and (Aiii-Diii) 25 μm. (Aiv-Div) Profiles of aequorin-generated light from α-actin-aeq transgenic embryos treated as described for (Ai-Di), respectively, from 17 hpf to 21 hpf (i.e., the ~16- to 24-somite stage). Data were plotted every 10 s, each data point representing 10 sec of accumulated luminescence for an ROI covering the entire embryo (i.e., 1.24 mm²).