Fig. 5. mezzo, casanova, bon/mixer and ntl are immediate early targets of Nodal signalling, while sox17 requires post MBT protein synthesis. Embryos at the one- to four-cell stage were microinjected with 50 pg of TARAM-A^* mRNA, treated continuously with 50 µg/ml of cycloheximide, starting at the 64- to 128-cell stage and analysed at dome-30% epiboly stage for the expression of sox17 (A-E), ntl (F-J), mezzo (K-O) and casanova (P-T). (A,F,K,P) Untreated and uninjected control embryos. (B,G,L,Q) Uninjected control embryos treated with cycloheximide. (C,H,M,R) Control untreated embryos injected with TARAM-A^*. (D,E,I,J,N,O,S,T), Embryos injected with TARAM-A^* and treated with cycloheximide. Although treatment with cycloheximide prevents induction of sox17, some ectopic mezzo, ntl, bon/mixer and cas expression is clearly visible in absence of protein synthesis.