Figure 1.

B. subtilis essential gene homologues are widely conserved. (Upper) Genes are ordered by their relative abundance among 54 Bacteria (blue) and 18 Archaea and Eucarya (red). The position (rank) of a gene is shown on abscissa and the fraction of organisms in which a gene is present is shown on the ordinate. (Lower) Fraction of genes present in different kingdoms of life (a gene counted as “all kingdoms” is present in at least one archaeon and one eukaryote, in addition to bacteria, whereas a gene counted as “bacteria” is not present in any archae or eukaryote). The list of genes and organisms is presented in Table 4.