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Fig. 1 ndr1overexpression in zebrafish blastulas identifies known and novel Nodal target genes. (A) Heatmap of a representative selection of genes induced on ndr1 overexpression across the full range of P values and fold changes. Genes previously identified as Nodal target genes in zebrafish are in bold. (B)In situ hybridisation of wild type and ndr1 mRNA-injected embryos for foxa, klf3, nhsl1b, notum1a and smarcd3 at 50% epiboly showing upregulation in response to ndr1 and absence in MZoep mutant embryos that have no Nodal signaling. Animal views; dorsal to the right. Numbers on each panel indicate the number of embryos showing the phenotype depicted over the total number of embryos analysed. For foxa expression in MZoep mutants the remaining 13/36 embryos showed absent expression except for a patch on one side of the embryo. For nhsl1b and notum1a the remaining 8/26 and 5/37 embryos, respectively, showed reduced expression around the margin. (C) Comparison of all genes represented on the microarray, or ndr1-responsive genes (either up- or down-regulated) to proximal Smad2 binding; comparison was performed for both all and novel ndr1-responsive genes. Compared to all genes on the microarray or those that are down-regulated in response to ndr1, up-regulated ndr1-responsive genes (both all and novel) are significantly associated with Smad2 binding. *P =7 × 10-7; **P =1 × 10-40. (D) Examples of Smad2 binding upstream of known (tbx16 and flh) and novel targets; scale in reads per million reads.