Fraction of putative C. jejuni essential genes among genes of the same degree. C. jejuni genes in the higher confidence interaction map (confidence score > 0.5) were collected into different groups according to their degrees (number of interacting partners). For each degree group the fraction of putative essential genes was computed and plotted as shown. Solid lines in the graphs were fitted using the available data points. The r-values represent Pearson correlation coefficients between fractions of putative essential genes and their degrees. (a) Putative C. jejuni essential genes are orthologs of E. coli genes identified as essential by Baba et al., . (b) Putative C. jejuni essential genes are orthologs of B. subtilits genes identified as essential by Kobayashi et al., . (c) Putative C. jejuni essential genes are the intersection of genes predicted to be essential from the E. coli and B. subtilis sets. (d) Putative C. jejuni essential genes are the union of the E. coli and B. subtilis sets.