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Fig. 8-S1
id3 mediated patterning of the mediolateral mesodermal axis is coordinated with AP axis formation.
A stage series of heat-shock inductions using the HS:id3 transgenic line indicates that Id3 patterns mesoderm in coordination with anterior posterior axis formation. Early stage heat-shock inductions inhibit myod and expand kdrl expression mostly in anterior regions but posterior tissues are normal (C–F). An intermediate stage induction at the end of gastrulation inhibits myoD and expands kdrl everywhere except the extreme anterior and posterior regions (G, H). At later stages during somitogenesis, id3 induction inhibits myod and expands kdrl expression in posterior but not anterior regions (I–L). Two heat-shock inductions at early and late stages indicates that recovery of posterior patterning in single early heat-shock inductions is due to turnover of the induced Id3 protein (M, N).