Distribution of 157 genes negatively selected within different functional categories. Classification and categorization of genes was done essentially in accordance with Glaser et al.  and the L. monocytogenes genome sequence provided by the Pasteur Institute http://genolist.pasteur.fr/ListiList/. Categories which no gene or one gene only (1.6 protein secretion, 1.7 cell division, 1.10 transformation, 3.7 protein synthesis) was assigned to were not listed, but the genes are included in total numbers (bold letters). For each category, the percentage of gene numbers relative to the total gene number in the L. monocytogenes genome (blue) and the number of genes with a Caco-2 infection phenotype relative to the total number of genes selected (red) is shown. For each class and category, the number of genes identified is indicated in brackets. 16 genes only recently identified  are included.