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Figure 1. Gsc-mediated CE phenotypes in Xenopus.(A) Experimental design. Specimens were injected with Gsc-GR into the dorsal marginal region of the 4-cell embryo and cultured to the stages indicated, with or without addition of dex. (B–E) Gsc-GR induced NTD and BPD in whole embryos. Specimens were scored for wt appearance (blue; B), NTD (green; C) and BPD (red; D). Anterior is to the left in (B–D). (E) Compilation of results. Note that Gsc-GR caused CE phenotypes in a highly significant proportion of embryos, but only when activated before and during gastrulation. Note also that deletion of the homeodomain (∆HD) or altering the DNA-binding specificity (K197E) prevented BPD/NTD-induction, while the repression domain GEH was not required for BPD/NTD. (F–I) Impaired CE of the notochord upon sustained dorsal Gsc-GR expression. Note that the notochord was wider and shorter in dex-treated (G,I) as opposed to untreated (F,H) specimens, both at stage 14 (F,G) and stage 19 (H,I). (J,K) Repression of Xbra transcription on the dorsal side upon Gsc-GR activation. (L,M) Double axis formation (M) following ventral injections of Dgsc mRNA into 4-cell Xenopus embryos (L). |
