Fig. 2

Two T-box binding sites proximal to tbx6 are necessary to drive reporter gene expression in the PSM of zebrafish embryos. (A-F) Expression patterns of EGFP signals and EGFP mRNA during embryogenesis in Tg(tbx6:EGFP) embryos (A-F; n=24). Whole-mount in situ hybridization was carried out to compare the distributions of EGFP mRNA (A′-F′; n=10) and endogenous tbx6 mRNA (A″-F″; n=10). Animal pole views (A-A″), dorsal views (B-B″) and lateral views (C-F″). All the photos are taken at the same magnification. Scale bar: 100 µm. (G-M) Several EGFP reporter genes that possess a base substitution of these binding sites were injected into zebrafish embryos to examine the cis-regulatory activities. The base substitutions introduced at T-box binding sites and the E-box site are shown below the corresponding sequences in Fig. S3A. EGFP fluorescent signal was observed at the 15- to 18-somite stages. Representative images are shown in lateral view. Detailed results are shown in Table S1. Scale bar: 100 µm.