The expressions of <i>tbx5</i> and <i>tbx20</i> were modulated by <i>Nkx2.7</i>.

<p>Each embryo derived from transgenic line Tg(<i>cmlc2</i>::GFP), whose heart was specifically tagged with green fluorescent protein, was injected with 0.15 ng of plasmid, in which <i>Nkx2.7</i> 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 <i>GR-Nkx2.7</i>-overexpression embryos were shown. Compared to the control (A), various cardiac defects were found in around 35% of embryos from the <i>GR-Nkx2.7</i>-overexpression group, including unlooping and shrunken heart (B). In addition, the expressions of <i>tbx5</i> (C, D) and <i>tbx20</i> (E, F) were down-regulated in the <i>GR-Nkx2.7</i>-overexpresion embryos. However, the expression levels of <i>tbx5</i> in eyes (indicated by arrows in C and D) and <i>tbx20</i> in brain (indicated by arrows in E and F) remained unchanged. v: ventricle; a: atrium.