Periodicity of transcriptional activity. The periodograms of the average transcriptional levels of MG1655 at 37°C (A), MG1655 following heat shock (B), MDS42 at 37°C (C), and MDS42 following heat shock (D), with the highest (major) peaks at 663, 773, 663, and 663 kb, respectively. The vertical, broken line in red indicates the major peak at 663 kb. The significant periodicities at the 95% confidence level are indicated by blue dashed lines. The expression levels of 4428 and 3710 genes were plotted for MG1655 and MDS42, respectively. In addition, the periodicities of the expression of the 3710 common genes in MG1655 at 37°C (E) and following heat shock (F) are plotted against the MDS42 genome. The average transcriptional levels of the genes for every 100-bp sliding window are shown as black lines, and the corresponding periodicities are shown as red curves. The location of the origin of replication (ori) is indicated by the black broken line, and the deleted segments from MG1655 are indicated by black bars. The average expression represents the log-scale mRNA concentration. The spectral power calculated with Fourier transform indicates the strength of the periodicity of the average expression along the genome.
Ying et al. BMC Genomics 2013 14:25 doi:10.1186/1471-2164-14-25