Figure 4. Anterior repression of zen does not require transcriptional activity of Bcd.

(A, B) Expression of two copies of Bcd-A₉ construct driven by Bcd promoter in the bcd null embryos (Bcd-A₉;bcd) results in MAPK phosphorylation (A) and nuclear Cic (B) gradients that are indistinguishable from those in wild type embryo (error bars are s.e.m). The numbers of embryos used in the analysis are: N_WT = 32, N_mutant = 19 for (A) and N_WT = 28, N_mutant = 24 for (B). (C, D) Quantified gradients of MAPK phosphorylation (C) and Cic downregulation (D) in bcd null embryos (error bars are s.e.m). N_WT = 28, N_mutant = 28 for (C) and N_WT = 39, N_mutant = 38 for (D). (E–H) Expression of otd (E), hb (F), kni (G), and hkb (H) in embryos derived from bcd homozygous (first column), bcd heterozygous (second column), wild type (third column), and bcd homozygous with Bcd-A₉ (fourth column) flies. Anterior expression of these genes is significantly reduced in Bcd-A₉;bcd embryos. (I, J) Nuclear Dl and zen mRNA in a Bcd-A₉;bcd embryo: similar to wild type embryos, zen is repressed at the anterior pole. (K, L) zen expressions at the anterior (K) and posterior (L) poles also show that zen is not expressed at the anterior pole in this mutant background. (M, N) Nuclear Dl and zen mRNA in a bcd null embryo. (O, P) zen expression at the anterior (O) and posterior (P) poles of embryos from bcd null flies.