Eomesa and Tbx16 are redundantly required for mixl1 expression in the presumptive endoderm. (A) Timing of expression of T-box factors (eomesa, eomesb, tbxta, tbx16) under study and presumptive endoderm (mixl1, gata5, sox32) and endoderm markers (gata5, sox32, sox17) indicated by bulk RNA-seq data from (White et al., 2017). Gene expression is shown as transcripts per million (TPM). Stages are as defined by (Kimmel et al., 1995). (B) UMAP clustering analysis of single-cell RNA-seq data for early gastrulas (6 h.p.f.) zebrafish embryos (Wagner et al., 2018) indicating colour-coded cell type identities. Cell types relevant to the present study are labelled. The identities of all cell types are indicated in Supplementary Figure S3. (C) UMAP clustering analysis of single-cell RNA-seq data for early gastrulas (6 h.p.f.) zebrafish embryos indicating co-expression of tbx16 and mixl1 (Wagner et al., 2018). Heatmap insets indicate overall expression levels per gene and co-expression. Overlapping expression is shown in yellow. (D) WISH analysis of mixl1 in early gastrulas (5.7–6 h.p.f.) zebrafish embryos in wild type or eomesa mutant embryos (see Methods for information on genotype) with and without Tbx16 morpholino knockdown. Total numbers of embryos and fractions as categorised are indicated. Animal views; dorsal to the right. Open arrowheads indicate normal mixl1 expression at the blastoderm margin. Closed arrowheads indicate profound loss of mixl1 expression on tbx16 knockdown in eomesa mutants.
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