Table 1. Orthologues of E.coli genes for the stress subset and for the remaining genes, identified with the stringent criteria defined in Materials and Methods.

	Stress		Others		Comparison
	No. of orthologues	No. of repeats	No. of orthologues	No. of repeats	P <
C.crescentus	136	27.4	1110	21.7	0.002
E.coli O157:H7	282	11.2	3382	7.9	0.001
H.influenzae	154	13.5	1073	11.1	0.003
M.loti	154	21.4	1378	17.1	0.005
N.meningitidis	117	17.4	943	12.7	0.001
P.multocida	169	11.2	1292	8.8	0.001
P.aeruginosa	196	26.8	1773	21.7	0.001
S.enterica	274	11.7	2789	9.0	0.001
S.meliloti	139	18.0	1151	13.9	0.003
V.cholerae	189	10.1	1675	7.1	0.001
X.fastidiosa	125	10.9	944	8.2	0.003
Y.pestis	216	8.7	2132	6.8	0.001

The table displays the average number of repeats in each subset of orthologs, and the comparison between the stress subset and the remaining genes in the genomes (Wilcoxon test).