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Figure 8. Different effects of TVGR (a hormone inducible form of XTcf3) and its subsequent activation on the expression of four Hox genes. Embryos were injected at the two-cell stage with 50 pg of TVGR DNA into each cell; before gastrulation CHX was added to prevent protein synthesis, followed by co-addition of DEX to trigger activation of the hormone inducible system. Embryos were fixed after the standard treatment (see Experimental Procedures section). Each row shows in situ hybridizations with probes for the respective genes noted on the right hand side; each column corresponds to the conditions described on top of it. Injection of TVGR does not significantly alter the normal (NIC) expression pattern of these genes, except for Hoxb1, which shows some ectopic expression. Addition of DEX in injected embryos causes substantial up-regulation of Hoxd1, Hoxb1, Hoxa1 and Hoxc6. Co-addition of CHX and DEX in TVGR injected embryos triggers a massive induction of both Hoxd1 and Hoxa1, as well as induction of Hoxb1; under these conditions, Hoxc6 up-regulation caused by DEX alone on TVGR injected embryos is now abolished. All views are vegetal. |
