Figure 6From: The impact of horizontal gene transfer in shaping operons and protein interaction networks – direct evidence of preferential attachmentDistribution among the COG categories for those E. coli genes that are members of operons. Counts were estimated for each evolutionary gene category, and expressed as percentages per total number of genes per COG category. The Core, Non-core and HGT gene sets contained within operons differ in their distribution of COG functional categories (P-value < 0.001).Back to article page