Fig. 7. Elevation of dpp⁺ dosage restores amnioserosa in sog^YSO6 embryos. (A-C) Dorsal views of stage 6a embryos hybridized with digoxigenin-labeled Race riboprobes showing Race expression in the presumptive amnioserosa. (A) Distribution of Race mRNA in a wild-type embryo. At this stage Race mRNA is present only in the 10% dorsal-most cells. (B) Race mRNA is absent in the presumptive amnioserosa in a sog^YSO6 embryo. Weak staining is present in the anterior dorsal region of the embryo. (C) Race expression is partially restored along the AP axis in a sog^YSO6 embryo that carries an extra copy of Mad¹². Race expression is expanded compared to wild type in the dorsolateral regions of the embryo. From a cross of sog^YSO6/FM7 females with Dp(2;2)DTD48 males, 51% (n=78) of the sog^YSO6 embryos showed partially restored Race staining. (D-F) Lateral views of stage 13 embryos stained for ß-galactosidase activity driven by a P[Kr-lacZ] construct expressed in the amnioserosa. (D) Wild-type embryo. (E) sog^YSO6 mutant embryos do not differentiate amnioserosa as evidenced by the absence of ß-galactosidase activity. (F) Restoration of amnioserosa in a sog^YSO6 embryo by the presence of an extra copy of dpp⁺. From the same cross as above, 51% (n=70) of the sog^YSO6 embryos showed restoration of ß-galactosidase staining in the amnioserosa.