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Fig. 6. XPteg acts upstream of Lim1 and Pax8 in inducing pronephric mesoderm (A). XPteg induced more ectopic expression of pronephric markers including Lim1 and Pax8 in response to activin RNA. Animal cap explants were dissected at stage 9 from embryos injected with Lim1, Pax8 or XPteg RNAs with or without activinβB RNA (5 pg), cultured for 3 days and analyzed by RT-PCR. Co AC, control animal caps. (B) Enhancement of SMP30 expression by Lim1, Pax8 and XPteg. Ectoderml explants isolated from Lim1, Pax8 or XPteg-injected embryos were treated with activin protein (10 ng/ml) for 3 h, cultured in Steinberg’s media for 3 days and processed for in situ hybridization with SMP30. (C) Coinjection of Lim1 or Pax8 could recover defective proximal expression of SMP30 and Pax2 in XPteg-depleted embryos (white arrowheads). Eight-cell stage embryos were injected with XPteg MO (10 ng) along with or without Lim1 (250 pg) or Pax8 (125 pg) RNA and later analyzed for SMP30 and Pax2 expression. |