Figure 2

Heatmap of genes showing significant changes in levels of expression between the progenitor mesenchyme at birth and the mesenchyme at day 2 of life. Fifteen microarrays, three daily from birth (P0) to post-natal day 4 (P4), were used to define the progression of gene expression in the mouse kidney beginning with the multi-potential progenitor mesenchyme and continuing through induced mesenchyme to early renal vesicles. a) The expression level of twenty genes increased between P0 and P2, whereas the level decreased for fifty genes (blue signifies low, yellow intermediate, and red high levels of expression). The pattern over the entire 4-day period is shown with each column representing the expression levels of a single microarray. Hierarchical clustering divides the genes into groups with similar expression patterns. For example, three genes, Tpi1, Aldoa, and Pfkl, are part of a cluster towards the bottom of the figure. Their levels of expression decreased early, decreasing by P1, and then remained stable through P4. Other clusters of genes with decreasing levels show a continued decrease, or did not demonstrate a decrease until P2. b) For comparison, the heatmap shows the pattern of expression of genes commonly identified with capping mesenchyme. The patterns illustrate changing levels of expression later in the course after birth.