(G-C)/(G+C) values (GC-skew) plotted every 5000 bp for Fusobacterium nucleatum, the low-GC Gram positive Clostridium tetani and the bacteroidete Bacteroides thetaiotaomicron. Red wide arrows represent replication origin (bottom) and terminus (top). Orange thin arrows indicate the 36 "clusters" of four or more contiguous genes that are potentially transferred from species outside the Firmicutes. Note that some of F. nucleatum shifts in GC skew coincide with putative HGT regions.
Mira et al. BMC Evolutionary Biology 2004 4:50 doi:10.1186/1471-2148-4-50