Comparative genomic hybridization data. (A) Histogram of the log2 ratio values (M-values) from one of the NCTC 11168 vs. NCTC 11168 (self-self) hybridizations, providing an estimate of the noise level associated with DNA extraction, labeling and hybridization. (B) The effect of probe-target sequence similarity on M-values using data from the RM1221 vs. NCTC 11168 comparison. The line is a locally weighted regression curve generated using the lowess function. (C) M-values vs. probe order according to position in the NCTC 11168 genome showed some regional clustering of divergent or absent genes to genomic hotspots for high variability. Data shown for isolate H441.