Fig. 10. (A) The initial phase of reporter gene activation in response to VegT requires intact T box sites. The indicated reporter constructs were injected into Xenopus eggs at the one-cell stage along with the VegT RNA or, as a control, lacZ RNA. Animal caps were dissected at stage 9 and cultured for 2 or 3 hours, as indicated. Analysis of luciferase activity shows that reporter gene activity was abolished by mutation of the T box sites in the 2-hour time-point, but not in the 3-hour time-point. (B) Activation of the indicated reporter constructs in Xenopus oocytes. Mutation of Tbs1 causes a dramatic reduction in luciferase activity and mutation of both sites abolishes the ability to respond to VegT.