Responsiveness of Tg(12xSBE:EGFP)ia16 line to Smad3. (A) Brightfield and fluorescent lateral images of smad2-, smad3a-, smad3b- and smad4-morphants at 24 hpf at the epifluorescent microscope, left to right. smad2, 3a and 3b morphants show a similar phenotype: anterior truncation, a curved shortened body axis, absence of floorplate and an enlarged intermediate cell mass. smad4 morphants exhibit the most severe phenotype: similar characteristics of the other morphants accompanied with a shortened body due to BMP inhibition. Reporter expression is completely inhibited in smad4 and 3a morphants and strongly reduced in smad3b morphants. smad2 morphants lack GFP expression in the cardiac mesoderm and telencephalon (white arrow head) and display a mild reduction in the neural tube. (B) Phosphorylated-Smad3 correlates to reporter expression in the 12xSBE line. Confocal lateral views of double fluorescent immunohistochemistry for GFP (green) and phosphorylated Smad3 (red) on embryo and larva tails at 24 and 48 hpf; zoomed views on the edge of the tail of a 24 hpf embryo. Arrowheads point to GFP/p-Smad3 double positive cells.
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