Fig. 3. Overexpression of vox or vent but not vox^st9 can counteract the expansion of dorsal mesodermal fates in Df^st7 mutants. Expression of gsc in wild-type (+) and Df^st7 embryos injected with synthetic mRNA for lacZ, vox, vox^st9 or vent. (A,E) 50 pg lacZ, (B,F) 50 pg vox, (C,G) 50 pg vox^st9 or (D,H) 30 pg vent mRNA was injected into 1-4-cell stage embryos from Df^st7/+ intercrosses. Embryos were fixed at 40% epiboly (5 hours) and expression of gsc was examined by in situ hybridization. In clutches injected with lacZ (n=36) or vox^st9 (n=41), gsc expression was normal in about three-quarters of the embryos and strongly expanded in about a quarter of the embryos. In contrast, no embryos had strongly expanded gsc expression in clutches injected with vox (n=38) or vent (n=54); gsc expression was weakly or partially expanded in about 13% (vent) or 16% (vox) of these embryos, while expression was normal or reduced in the other embryos of these clutches. In B,D,F,H, genotypes (+ or Df^st7) were determined by PCR assay after the photographs were taken. Animal pole views, dorsal towards the right. Similar results were obtained using chd expression to monitor the expansion of dorsal fates (data not shown).

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