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FIG. 5. Ectopic expression of xGATA-4/5/6 genes specifically activates the transcription of cardiac-specific genes but does not disrupt heart
development. (A) Quantitative RT/PCR was used to measure transcript levels of the MHCa gene, in RNA derived fromstage 9 embryos. Embryos
were injected at the one-cell stage with RNA encoding xGATA-1 (G1), a nonfunctional mutant form of xGATA-4 (mG4), xGATA-4 (G4),
xGATA-5 (G5), xGATA-6 (G6), or the anti-sense strand of xGATA-5 (not shown; this gave identical results to mG4). (B) In the same manner,
transcript levels were analyzed for the cardiac actin gene. Although these data do not show a significant activation by GATA-6, in multiple
experiments we have not detected a significant difference in the ability of each GATA-4/5/6 gene to activate transcription of the target genes.
(C) Whole mount in situ hybridization experiments were used to analyze expression patterns of cardiac actin and MHCa in untreated and
injected embryos. Top row (c-actin, stage 32) left to right: uninjected, xGATA-4 injected, xGATA-5 injected. Middle row (c-actin, stage 25) left
to right: uninjected, xGATA-4 injected. Bottom row (MHCa, stage 32) left to right: uninjected, xGATA-4 injected, xGATA-5 injected. Similar
results were obtained for xGATA-6 injected embryos (not shown). Embryos were either wild-type (pigmented) or albino. |
