Frog axis cheat sheet
Frog axis cheat sheet
Frog axis cheat sheet
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<strong>Frog</strong> <strong>axis</strong> <strong>cheat</strong> <strong>sheet</strong> – Zoo 470 2013 – Page 4<br />
Step 3: β-catenin accumulates in the nuclei of dorsal cells. This leads to the expression of genes by<br />
Nieuwkoop Center cells in the next step.<br />
Step 4: The Nieuwkoop Center<br />
forms. Ventral vegetal cells<br />
differentiate as endoderm, due in part<br />
to VegT (and possibly Vg1). Dorsal<br />
vegetal cells differentiate differently,<br />
due to the added effect of β-catenin.<br />
Tcf/Lef proteins, in combination with<br />
β-catenin, lead to expression of<br />
siamois and twin (transcription<br />
factors) and other genes in these<br />
cells.<br />
Step 6: Mesoderm is induced in overlying<br />
marginal zone tissue by vegetal cells. The<br />
character of the induced mesoderm reflects the<br />
character of the underlying vegetal cells.<br />
Gilbert, 9e, Fig. 7.21<br />
Gilbert, 8e, Fig. 10.25<br />
Step 5: Graded expression of Nodal-related proteins arises in vegetal<br />
cells. This creates a full spectrum of D-V differences.<br />
Wolpert, 2e, Fig. 3.35
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