Figure 3
Clusters of differentially expressed genes in response to intramammary infusion of S. aureus. Microarrays were performed on tissue from each mammary quarter with data compared to the intramammary control for each cow to identify differentially expressed transcripts. The figure shows the mean gene expression cluster profiles for the significantly differentially expressed elements that were either up-regulated (a) or down-regulated (b) relative to the control in response to intramammary infusion of S. aureus. The clusters only contain significantly differentially expressed elements that were expressed in all samples and showed at least 2 fold change relative to the control in at least one sample. RNA samples were obtained from mammary tissue of three Holstein Friesian cows at peak lactation that had been infused with pyrogen-free PBS (dose 0, n = 3) in one quarter (intra-animal controls) and in other quarters with S. aureus at dose rates of 500 (n = 1), 10,000 (n = 2), 100,000 (n = 3) or 1,000,000 (n = 2) bacteria. Data are expressed as log2 (fold change) ± 1 S.D. for the centroid of the cluster.