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Fig. 7. Different regulation of Nodal target genes by bon and
sur. All embryos are at 50% epiboly; animal pole view except M-P,
which are lateral views. (A-D) Expression of gsc in prechordal plate
progenitors is weakly reduced in bon (B), strongly reduced in
MZsur (C) and absent in MZsur;bon mutant embryos (D). (E-H)
Expression of bik is not affected in bon (F) but
downregulated in MZsur (G) and MZsur;bon (H) mutant embryos.
(I-L) Expression of mezzo is not affected in bonMO (J) but
downregulated in MZsur (K) and MZsur;bonMO (L) embryos.
(M-P) Expression of cas in endodermal progenitors (arrows) is
strongly reduced in bon (N) and MZsur;bon (P) mutant
embryos. Notice that cas expression in the yolk syncytial layer is
not regulated by Nodal signaling. Expression of snail (Q-T) and
flh (U-X) are not affected in any of the mutants.