Figure 3

Heat map and Northern dot expression analysis of S. meliloti sra genes. Heat map visualizing the expression values for each sra gene at various stages of growth (in LB medium). Signal intensities are indicated as signal-to-noise SNR values (log2 scale), represented by a red panel. The position of each sra gene in the heat map is determined by its intensity. For the complementary Northern dot analysis, 10 μg of RNA, isolated from the most favourable expression condition, was spotted (in duplicate) onto a nylon membrane and hybridized with a radiolabelled specific probe [see Additional file 8].