Are the constancy of global regulation across a species : the concentrations of ppGpp and RpoS strain-specific in Escherichia coli?
The ppGpp and σS variance means that the expression of genes involved in translation, stress and other traits affected by ppGpp and/or RpoS are likely to be strain-specific and suggest that influential components of regulatory networks are frequently reset by microevolution. Different strains of E. coli have different relationships between ppGpp and RpoS levels and only some exhibit a proportionality between increasing ppGpp and RpoS levels as demonstrated for E. coli K-12.
Pseudotumors were not associated with increased wear or metal ion levels, suggesting patient susceptibility is likely to be more important.