Fig. 3

Fig. 3  SB-431542 treatment alters marker gene expression in zebrafish embryos. Embryos were treated with 100 μM SB-431542 or DMSO at 16-cell stage, and harvested for in situ hybridization with (A, B) goosecoid (gsc), (C, D) no tail (ntl), and (E, F) even-skipped-1 (eve1) at shield stage, (G, H) ntl, (I, J) axial, and (I, J) pax2.1 at bud stage, and (K, L) shh at 18-somite stage. Gsc expression in the dorsal organizer region embryos is severely reduced in treated (A) versus control (B) embryos. In control embryos, ntl expression forms a ring around the margin (D), but expression on the dorsal side is lost in SB-431542-treated embryos (C). In contrast, eve1 expression is not affected (E, F). At bud stage, ntl expression in the tailbud (arrow) is normal, but notochord signal (arrowhead) is absent (G, H). Axial (arrows in panels I and J) expression is also lost in the presumptive notochord / floorplate. Pax2.1 expression is unaffected (arrowheads in panels I and J). By the 18-somite stage, shh expression is still severely reduced, with virtually no signal in the anterior of the embryo (compare panel K to arrow in panel L), and weak, discontinuous staining in the posterior (arrowheads in panel K). Shield stage embryos (A–F) are photographed with the dorsal side to the right. Bud stage embryos (G–J) are photographed with the anterior to the top.