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Fig. 1. Transcriptional repression by Gsc regulates anterior development. (A) Schematic of the Gsc fusion constructs. A C-terminal region of Gsc (residues 128-244), containing the homeodomain (HD), was fused to the Engrailed repressor (residues 1-298) (Eng-Gsc) or the VP16 activator (residues 410-490) (VP16-Gsc). At the four-cell stage, one ventral (C,E,G) or two dorsal (B,D,F,J,K) blastomeres were injected with 150 pg of Gsc (B,C), 150 pg of Eng-Gsc (D,E) or 500 pg of VP16-Gsc (F,G,J,K) mRNA. See Table 1 for quantitation. In situ hybridization for Otx2 (H,J) or En2 (I,K) and immunocytochemistry with the muscle antibody 12/101 (H,J) or the notochord antibody Tor 70 (I,K) were performed to assess the axial and neural development of VP16-Gsc-injected or uninjected (Control) embryos. White arrowheads indicate partial secondary axis (C,E) or cement gland (B,D). Black arrowheads indicate muscle (H,J) or notochord staining (I,K). Black arrows indicate Otx2 (H) or En2 (I,K) staining. Scale bar: 0.5 mm. |
