| |
Figure 1. Msx1, Pax3, and Slug Expression in the Presumptive Neural Crest Domain and Msx1 Neural Crest-Inducing Activity In Vivo and in Explants(A) Msx1 (a–d) and Pax3 (a′–d′) expression in X. laevis at stages 11 (a and a′), 13 (b and b′), and 16 (c–d′) costained with Krox20 (d–d′, indicates third rhombomere). Arrows in a–a′ indicate the blastopore lips at stage 11. a–a′, lateral views; b–d′, dorsal views.(B) Coexpression of Msx1 and Slug by double ISH (Msx1 [blue]; Slug [red]; a; b, dorsal views; a′–b′, transverse sections).(C) Msx1 mRNA was injected in one blastomere at the four cell stage, LacZ is revealed in pink (yellow arrow points at injected side). The embryos were analyzed at early (stage 13, a, c, e, and g) or late (stage 16, b, d, f, and h) neurula stages by ISH for Slug (a and b), Pax3 (c and d), Twist (e and f), and Sox2 (g and h) (red bar, uninjected neural plate half; yellow bar, width of the neural plate on the injected side). Dorsal views.(D–F) RT-PCR analysis of neural, ectoderm and early NC markers: Pax3 and ZicR1 (D); AP-2, Snail, and Slug (E); FoxD3, Pax3, Zic5, and Sox9 (F) after coinjection of Msx1 and Noggin. (D) Lane 4, Noggin (25 pg); lane 5, Msx1 (500 pg); lane 6, Msx1 (500 pg) + Noggin (25pg). (E) Lane 4, Noggin (25 pg); lane 5, Msx1 (100 pg); lane 6, Msx1 (500 pg); lane 7, Msx1 (100 pg) + Noggin (25 pg); lane 8, Msx1 (500 pg) + Noggin (25 pg). (F) Lanes 1–4, as in (E). Lanes 5–7, Msx1 (100–250–500 pg). Lanes 8–10, Noggin (25 pg) + Msx1 mRNA (100–250–500 pg). |
