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Figure 3. Reduction of Chordin and Overexpression of xTsg Synergize, Causing Ventralization of Xenopus Embryos (A) Uninjected wild-type embryo at stage 40, stained with the notochord-specific antibody MZ15 (A ) or the muscle-specific antibody 12-101 (A′). (B) Embryos microinjected with Chd-MO(1 2) at the two-cell stage have normal notochord staining (B ), but the muscles have adopted a U-shaped phenotype (B′). (C) Embryos injected once ventrally with 1 ng of xTsg mRNA at the four- to eight-cell stage. Note that the notochord is reduced and absent from the posterior in strongly affected embryos (C′). Muscle development is disturbed (C′), and muscles adopt a U-shaped phenotype. (D) Embryos coinjected with xTsg and Chd-MO(1 2) are strongly ventralized. (E) N-tubulin expression in stage 25 wild-type embryos, embryos injected at the two-cell stage with 8 ng Chd-MO(1 2), 1 ng xTsg mRNA, or both. (F) RT-PCR analysis of sibling embryos; Chd-MO(1 2) and xTsg mRNA cause the repression of anterior neural markers Rx2a (eye), Six-3 (forebrain), and engrailed (midbrain). The pan-neural marker NCAM and the dorsal mesodermal marker actin are reduced. The ventral mesodermal marker sizzled is upregulated by Chd-MO(1 2) injections, but repressed by xTsg mRNA injections (Chang et al., 2001). |
