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Fig. 7 Overexpression of Nkx2.5 and Nkx2.7 in embryos resulted in serious heart defects.
Amounts equaling 150 pg Nkx2.5 mRNA (A–C) and 5 pg Nkx2.7 mRNA (D–F) were injected individually into one-celled stage embryos derived from transgenic line Tg(cmlc2::GFP), whose hearts were specifically tagged with green fluorescent protein. We observed that there were many phenotypes of heart defects at 48 hpf resulting from the overexpression of either Nkx2.5 mRNA or Nkx2.7 mRNA. These defects included malposition of the reducing heart (A, D), bilateral heart (B, E), small heart (C) and large heart (F). Interestingly, overexpression by injection of Nkx2.7 mRNA as low as 5 pg caused an effect similar to that induced by injection 30 greater times than that of Nkx2.5 mRNA. (A, C, D, F), lateral views; (B, E), dorsal views; Arrows: green fluorescent heart.