Cdx4 regulates trunk hoxca initiation phase differentially in neural and paraxial mesoderm tissues. A–I: Expression analysis of hoxc4a (A–C), hoxc6a (D–F), and hoxc8a (G–I) genes in Cdx4-deficient (kggtv205 mutant) embryos at 60% epiboly (left column), 75% epiboly (middle column) and 95% epiboly (right-most columns). Embryos were photographed as described in Figure 4, slightly tilted from the vegetal pole, dorsal to the top. PCR was used to confirm cdx4 genotype. Expression of myod (red staining, adaxial cells) was used as a dorsal reference point to determine hox expression domain at the midline (white bars). Scale bar = 200 microns. J: Loss of Cdx4 reduces the level of hox transcription relative to wild-type levels. Levels of hox transcription were normalized to the housekeeping gene ef1α, and are for whole embryo extracts (neural and mesodermal tissues). RT-qPCR genes were selected to supplement in situ analysis and increase cluster coverage. Black bars are wild-type levels (one relative unit), and gray bars are for Cdx4-deficient embryos (morphants). Standard deviations are indicated. Asterisks indicate samples below limit of detection.
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