Gata4 is required for cardiac LR patterning. (A) The gata4 (e2) morpholino efficiently disrupted mRNA splicing. RT-PCR on mRNA from morpholino-injected embryos amplified a 188-bp product (exon 2 skipping) and a 268-bp product (intron 2 retention); RT-PCR from control embryos only amplified a 454 bp product (normal splicing). Normally spliced gata4 mRNA in these morphants was 2.8% of the wild-type level as revealed by real-time PCR analysis. (B,C) Reducing Gata4 resulted in laterality defects, which can be rescued by co-injection with gata4 RNA in a dose-dependent manner. (B) Quantification of cardiac looping. (C) Quantification of asymmetric expression of spaw, lefty2 and pitx2.
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