2) for 20 min and then labelled with [35 S]-methionine for 20 min. Proteins were Gefitinib research buy separated by their isoelectric point (pH 4–7) and then by their molecular weight on a 10%–20% Tris–HCl gel. The gel was scanned and only proteins, with incorporated [35 S]-methionine, were visible. Arrows point at induced proteins: 19 kDa periplasmic protein (p19), alkyl hydroperoxide reductase (AhpC), Superoxide dismutase (Fe) (SodB), Thioredoxin-disulfide reductase (TrxB), hypothetical protein (Cj0706), and molybdenum cofactor biosynthesis protein (MogA).

Quantitative RT-PCR Transcriptomic analysis using qRT-PCR technique was performed to determine if the proteins induced during acid stress were induced at transcription level. Figure  4 illustrates the transcription profiles represented by fold change relative to control of dps, cj0706, sodB, trxB, ahpC, mogA, p19 and fur during HCl and acetic acid stress for strain NCTC 11168. Interestingly, the transcriptomic data did not correspond completely with the

proteomic data (Figure  4). The increased gene expression of trxB (P HCl = 0.009) and p19 (P HCl, Ac < 0.05) during acid stress corresponded well with enhanced protein production. Especially noteworthy is the high acid stress response of p19 gene compared with the other genes. Proteins such as SodB and AhpC, which were not significantly induced in NCTC 11168, were, however, over-expressed at transcription level during acetic acid exposure (P sodB, Ac = 0.03, Buparlisib cell line P ahpC, Ac = 0.000). The regulator 5-FU clinical trial Fur was included in the qRT-PCR study because a search of putative Fur-regulated genes indicated that genes involved in iron-transport genes such as p19, cj0178, ceuB, cfrA, chuA, exbB, feoB and cfhuA and the iron-storage genes such as dps, ferritin (cft) and cj0241 all contained Fur box promoters [37]. Fur was not induced in the proteomic study, but there was a tendency, however not significant, that fur was over-expressed during acetic acid stress (P fur, Ac = 0.06). Figure 4 Relative change in transcription level during

acid stress of selected genes: dps , cj0706 , sodB , trxB , ahpC , mogA , p19 and fur analyzed by qRT-PCR. C. jejuni strain NCTC 11168 was grown to 1 × 10 8 CFU/ml and exposed to HCl (pH 5.2) and acetic acid (pH 5.7). The expression level of acid stressed for a specific gene was compared with unstressed cells and the horizontal line illustrates the fold change at 1.0 for the reference genes (rpoA and lpxC). Fold changes and standard deviations were calculated from the outcome of qRT-PCR runs from three microbiological independent experiments. Genes marked with an asterisk are significantly over-expressed compared with genes from non-stressed cells. Discussion Proteome analysis for Campylobacter during acid stress revealed different protein profiles between the strains and the type of acid used.