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Figure 1. Stage-dependent ablation of the pronephric anlage by Delta Smad7-mediated BMP inhibition. mRNAs encoding the Delta Smad7tevGR construct (300-400 pg) and the TEV2GR construct (10 pg) were injected into a single ventral blastomere at the 4-cell stage. The injected side of the embryo was identified via the presence of the lineage marker beta -galactosidase (pink). A,C: Anterior, uninjected side of embryos facing right. B,D: Anterior-injected side of embryos facing left. After injection, dexamethasone was added to the culture medium at stage 14, which is after the completion of renal field specification. The effects of stage-specific BMP inhibition on the development of the renal field were examined via in situ hybridization between stages 22-25 using the pronephric tubule and duct anlage markers (A,B) Xlim-1 and (C,D) Xpax-8. Following conditional inhibition of BMP signaling, expression of both genes was markedly reduced or ablated (B,D; black arrows) when compared to the uninjected-control side of the embryo (A,C; green arrows). Specifically, reduction or ablation of Xlim-1 expression was observed in 72% of injected embryos (n = 160), and reduction or ablation of Xpax-8 expression was observed in 67% of injected embryos. |
