Also, it is not clear why major stress response genes were down regulated in theluxSmutant and why this change is only seen in MHB but not MEM-α, as a metabolic defect would have been expected to generate stress conditions, rather than to reduce them. It is also noteworthy that the profile of stress-response linked genes differentially expressed in this study was not the same as that observed in the MHB grown stationary phase cells analysed by Heet al., 2008 [37], emphasizing that growth conditions have a significant
influence upon gene expression. It is interesting BTSA1 supplier that in this study the stress response was observed under the conditions where high levels of AI-2 were produced by the wild type. It must be emphasised, Cilengitide concentration however, that these changes could not be reversed by the addition of exogenous AI-2, which argues against a role of quorum sensing in this response. Contrary to a previous report [48], no downregulation of the cytolethal distending toxin genes (cdtA,BandC:Cj0079c,Cj0078c,Cj0077crespectively) was observed in theluxSmutant. This may be a reflection of the different growth times (we used 8 h, they 3 days), or strains used in the two studies (81116 by Jeonet al., 2005, NCTC 11168 here).
From Tables 1 and 2 [see Additional files 1 and 2] it is apparent that several sets of neighbouring genes were differentially regulated in a similar manner, suggesting that they may form KPT-8602 price operons and that their encoded proteins might function in the same pathways. For instance, the hypothetical iron-sulphur proteins Cj0073, Cj0074, Cj0075 appear to be transcriptionally linked Acetophenone with the putative lactate permease gene Cj0076 (lctP). Other examples include some of the flagellar genes, amino acid biosynthesis genes, and heat shock genes. Of particular interest is the observed down-regulation of 14 putative flagella genes in the MHB-grownC. jejuniNCTC 11168luxSmutant. This is in agreement with the reduction of motility in semi-solid MHB agar plates, as previously described for strains NCTC 11168 [35] and 81116 [44]. However, is
in contrast to the recently published transcriptional data of theluxSmutant ofC. jejunistrain 81-176 [37]. This may reflect the co-ordinate regulation exerted upon flagellar components and regulators, which, as Heet al. 2008 [37] pointed out, is influenced by bacterial growth phase and environmental factors. Both genes encoding cheomotaxis proteins (Cj0363, Cj0284c (CheA) and Cj0144) as well as the flagellin genesflaAandflaBwere among those found to be down-regulated in the present study. The former may impact upon motility [59], and the latter matches the findings of Jeonet al. (2003), who reported reducedflaAexpression forC. jejuni81116luxS, and showed that the flagellar structure was still preserved in this strain [44]. Reduced motility of theC.
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