Figure 2.

NC expression of AP2α depends on Wnt signaling. Whole-mount in situ hybridizations with NC markers Sox9, Slug, and AP2α to embryos injected into one cell at the two-cell stage with 100 pg of plasmid DNA encoding Xenopus Xwnt-1 (Left) and Xwnt-3A (Center), or 1 ng RNA encoding GSK3β (Right), along with a β-galactosidase lineage tracer (red staining). In all cases the injected side is oriented to the right (red staining). Both Wnt treatments resulted in lateral and posterior expansion of NC territory, including expression of AP2α as well as the other NC markers. The reciprocal treatment with GSK3β, which interferes with downstream Wnt signaling (50), had the opposite effect: AP2α, Sox9 and Slug all were repressed. (Magnification: ×15.)