Northern Blot Analysis of ica Genes

Staphylococcus aureus 132 and arl strains were grown in 10 ml of TSB-NaCl at 37°C under static conditions for 5 h. RNA extraction was performed as described previously (Lasa et al., 2011 (link)). Northern blots were performed as described (Ruiz de Los Mozos et al., 2013 (link)). Briefly, 8 μg of total RNA was separated in precast agarose gels (Sigma). RNAs were blotted onto Nytran membranes (0.2-μm pore size) (Amersham Biosciences), UV cross-linked, prehybridized in ULTRAhyb solution (Ambion) at 65°C, and labeled with strand-specific riboprobes specific for icaA, icaC, and icaR (Supplementary Table S2). Membranes were washed and autoradiography images were registered at different exposition times according to each gene.