Array hybridization results are presented as Additional file 1 and are deposited in GEO database http://www.ncbi.nlm.nih.gov/projects/geo/ under GSE12238 accession number. Results and Discussion General trends in selleck chemical transcription After determining transcript levels for all probe sets, the 1,994 transcripts were grouped into 15 clusters based on their behavior during growth (Figure PX-478 solubility dmso 2) (self organizing map algorithm; Array Assist 5.1.0 package, Stratagene). The clusters were grouped into five main categories. The first 3 categories contain genes whose transcription did not correspond to growth phase,
and were either expressed at low (cluster 0), medium (clusters 6, 7), or high (clusters 8, 9) levels in all phases of growth. Category 4 genes (clusters 1–4) exhibited increased transcription in ES or S phase, and category 5 genes (clusters 5, 10–14) had
transcription levels that peaked in ML phase and decreased into S phase. Selleckchem Captisol Figure 2 Grouping of S. agalactiae transcripts into distinct 15 clusters based on expression profiles from ML to S growth phases. The dendrogram and clusters were generated using a self organizing map algorithm and represent changes in expression of 1,994 transcripts at four consecutive time points: ML, LL, ES, and S phases. Cluster 0 genes had low level of transcription. Clusters 1–4 genes positively correlated with stationary phase of growth transcription level and peaked in the ES (clusters 1 and 2) or S (clusters 3 and 4) phase of growth. Clusters 5 and 10–14 are negatively correlated with the S phase of growth; transcription of genes grouped in these clusters reached their peak in ML phase and decreased in S phase. Genes in clusters 6–9 are Metalloexopeptidase expressed relatively steadily during growth although at various levels of expression, ranging from very high (cluster 9) to mid-low (cluster 6). The black horizontal line on the cluster graphs represents average transcription level
of the complete dataset. The transcript level in each cluster is plotted using a logarithmic scale. Number of transcripts in clusters: Cluster 0, 440; Cluster 1, 115; Cluster 2, 106; Cluster 3, 42; Cluster 4, 47; Cluster 5, 175; Cluster 6, 140; Cluster 7, 100; Cluster 8, 66; Cluster 9, 26; Cluster 10, 183; Cluster 11, 173; Cluster 12, 185; Cluster 13, 89; Cluster 14, 107. Genes exhibiting growth phase-independent transcription Genes in clusters 6, 7, 8, and 9 did not show growth phase-dependent transcriptional regulation. The genes are clustered instead based on their transcript level and general profile. Clusters 6 and 7 contain genes that are expressed at the same level until ES phase to slightly lower expression in S phase. Clusters 8 and 9 contain genes, which the transcript level is steady or slightly increases over time.