Figure 2

Taxonomic distribution and functional analysis of genes from fully sequenced genomes. On the basis of a raw BLAST score cutoff of 50, we determined the number of sequences with similarity of sequences derived from the three domains of life. (a) The Venn diagram shows the proportion of sequences associated with each group. Numbers in grey boxes show the proportion of sequences specific to their parent domain; numbers in white boxes show the proportion of sequences that are shared with one or more members of the same domain. The numbers in the overlapping regions of the diagram show the proportion of sequences shared between the overlapping domains: yellow, archaeal sequences; blue, bacteria; red, eukaryotes. (b) Pie charts showing the proportion of each functional category for three datasets of sequences: highly conserved sequences (with sequence similarity to every other complete genome dataset); semi-conserved sequences (with similarity to at least one species from each of the three domains of life); and sequences unique to a genome (possessing no similarity to any other genome dataset). Functional categories were assigned with reference to the KEGG database (see Materials and methods).