Figure 1

HIGK Gene expression upon P. gingivalis and S. gordonii single- and mixed infections. Hierarchical clustering was performed on variance-normalized signal of gene expression data from uninfected HIGK cells (CTRL) and from cells in co-culture with either organism or a mixture of both for 2 h before RNA isolation and purification. Probe set signal intensities were variance-normalized, mean-centered across samples, and subjected to hierarchical cluster analysis. Heat map and dendrogram were constructed from 6066 probe sets that were differentially expressed among the treatment conditions at a level of significance of p < 0.05. The degree of similarity between the transcriptional profiles of each sample is expressed by Pearson's correlation coefficient distance metric, according to the adjacent scale. The expression state of each data point is represented as standard deviations from the mean expression level for that gene in all samples. Red indicates a relative increase, green indicates a relative decrease, and black indicates no relative change of mRNA transcripts for a given gene.