Practice question

Dominant-negative GSK3 expressed in dorsal marginal zone further inhibits already partially suppressed GSK3 activity dorsally, leading to even greater beta-catenin stabilization and hyperdorsal phenotype. Extra beta-catenin expands organizer gene domains chordin and goosecoid laterally, converting paraxial and lateral mesoderm into axial notochord and somitic tissue, enlarging neural plate while reducing ventral blood islands and epidermis. This contrasts ventralization seen with constitutively active GSK3. Result is dorsalized embryo with radial neuralization and exaggerated dorsal structures due to enhanced Wnt signaling. This illustrates conserved developmental logic of morphogen gradients patterning embryonic axes through Wnt and BMP antagonism.