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Fig. 8. VP16-Gsc alters gene expression at the gastrula and neurula stages. At the four-cell stage, two dorsal blastomeres were injected with 500 pg of VP16-Gsc. Embryos were fixed at stage 10.5 (early gastrula), 12.5 (late gastrula), 15 (mid-neurula) or 20 (late neurula). Gene expression was detected by in situ hybridization of uninjected (Control) and VP16-Gsc-injected embryos. VP16-Gsc caused an expansion of Xwnt8 (B) and MyoD (F) into the dorsal marginal zone at stage 10.5, and MyoD-positive cells were present at the midline (white arrow) at stage 15 (H). Frzb and Chordin expression in the organizer was not affected at stage 10.5 (D,J) and Chordin expression in the chordamesoderm was normal at stage 15 (L). Otx2 was reduced or absent at all stages examined (N,P,R,T). Opl expression in the prospective neural plate was not affected by VP16-Gsc at stage 10.5 (V), but was absent from the most anterior domain of the neural plate (bracket) at stage 12.5 (X). Black arrowheads indicate the dorsal blastopore lip. The black arrows indicate the primordia of the forebrain (fb), eyes (e) and cement gland (cg) (S). Vegetal views are shown in A-F,I,J,M,N, dorsal view is shown in G,H,K,L,U,V with anterior on the left in G,H,K,L and anterior view is shown in O-T,W,X. Scale bar: 0.5 mm. |
