Fig. 4. Requirement of potential ZicL-binding sites for Ci-Bra expression in notochord cells. Reporter gene expression in embryos microinjected with (A-C) p(-483)Ci-Bra/lacZ and (D-F) p(-3.5k)Ci-Bra/lacZ, revealed by whole-mount in-situ hybridization. (A,B,D,E) Constructs without mutation or (C,F) ZicL-b1/ZicL-b2 double-mutations were introduced and examined at the (A,D) 64-cell stage or (B,C,E,F) 110-cell stage. (G) The frequency of the tailbud stage embryos with the reporter gene expression, revealed by histochemical detection of ß-galactosidase activity. The electroporated Ci-Bra/lacZ fusion genes with the mutated ZicL-binding sites are listed on the left. Reporter gene expression in embryos electroporated with (H-K) p(-483)Ci-Bra/lacZ and (L-O) p(-3.5k)Ci-Bra/lacZ. (H,L) Constructs without mutation, (I,M) ZicL-b1 mutated, (J,N) ZicL-b2 mutated or (K,O) ZicL-b1/ZicL-b2 double-mutated. High-magnification images of the embryos are shown in insets.