Figure 4

Detection and location of chromosomal S. meliloti sRNAs. A. Total RNA was extracted from cultures grown in LB (mid-exponential phase). Northern blots were hybridized with biotinylated DNA oligonucleotide probes [see Additional file 8] and exposed for various times (therefore the intensities of the signals do not correspond to the relative abundance of each sRNA). The positions of RNA size standards are shown on the left. B. Distribution of the sra genes along the S. meliloti chromosome. The origin of replication (oriC = sra01) and positions of tmRNA, rnpB and 4.5S are also indicated. Blue and red arrows represent genes on the reverse or forward strands, respectively. Genomic islands are indicated with grey boxes (Sme21T, Sme19T and Sme80S).