Fig. 7. Functional analysis of a candidate protomap component, Mest/Peg1, reveals a role in Fgf8-mediated patterning of rostral cortex. (A) Gene expression changes in the E12.5 Mest mutant neocortex. A hierarchical cluster analysis of the set of genes showing statistically significant differences in gene expression between E12.5 Mest mutant and wild-type cortices. (B) Changes in the expression of genes showing higher rostral and caudal expression in the E13 microarray screen in the Mest mutant cortex. Note that approximately 20% of such rostral genes are upregulated in the Mest mutant and a similar percentage of caudal genes are downregulated. (C) Caudal patterning genes (red) are downregulated and rostral patterning genes are upregulated (green) in the Mest mutant E12.5 cortex. The average gene expression change (n=6 hybridisations) for each gene is shown. (D,E) A comparison of Klf3 expression in E12.5 wild-type and Mest mutant neocortex shows marked changes in both the level of expression and the extent of the rostrocaudal gradient, with a caudal shift of the gradient in the mutant cortex. Fluorescent in situ hybridisation on parasagittal sections from mutant (E) and wild-type (D) E12.5 embryos is shown, with rostral to the left. Arrowheads indicate the rostral region of Klf3 expression in each section.