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Fig. 8 The expressions of tbx5 and tbx20 were modulated by Nkx2.7.
Each embryo derived from transgenic line Tg(cmlc2::GFP), whose heart was specifically tagged with green fluorescent protein, was injected with 0.15 ng of plasmid, in which Nkx2.7 mRNA was transcribed conditionally by adding dexamethasone. All embryos were treated with dexamethasone at 10 hpf and took a ventral view at 48 hpf to observe the cardiac development under the fluorescence microscope. The cardiac morphologies of the control embryos and the GR-Nkx2.7-overexpression embryos were shown. Compared to the control (A), various cardiac defects were found in around 35% of embryos from the GR-Nkx2.7-overexpression group, including unlooping and shrunken heart (B). In addition, the expressions of tbx5 (C, D) and tbx20 (E, F) were down-regulated in the GR-Nkx2.7-overexpresion embryos. However, the expression levels of tbx5 in eyes (indicated by arrows in C and D) and tbx20 in brain (indicated by arrows in E and F) remained unchanged. v: ventricle; a: atrium.