Figure 2

Cluster analysis of temporal transcriptional response elicited by S withdrawal (-SO ₄ ^2-/-HEPES). A. A heat map of a hierarchical cluster of genes significantly affected by S deprivation. A gene was deemed significantly affected if its transcript level deviated from a 0-hr level by at least 50% in at least 1 time point across the time course (FDR<0.01). Hierarchical clustering was performed by complete linkage algorithm using Pearson correlation as a similarity metric. The log₂ (ratio) of each gene is represented according to the shown color scale. 20 clusters were delineated based on a correlation coefficient (r) cut-off of 0.50, shown to the right of the heat-map. Numbers given in parentheses represents the number of genes contained in each cluster. B. The transcriptional profile of each cluster. The data are represented as a mean ± s.e.m.