Since both mutants and wild types were grown in a rich medium, the effect of CodY on alteration of gene expression in our strains is not known. In addition, microarray analysis also detected some regulatory genes that were downregulated in both mutants (Table 3) and some that were upregulated in NCTRR and downregulated in 13124R (Table 1). Among those genes that were affected differently was CPF_0069, which
is a transcription antiterminator similar to the BglG-type regulators in other bacteria (http://www.ncbi.nlm.nih.gov/). This gene was downregulated in 13124R and upregulated in NCTRR. At this point, the roles that this gene and others play in altering the transcription Cediranib cost of toxin genes in resistant strains are not known. Nor is there a reason known for the check details contradictory effects of fluoroquinolone resistance selection on the expression of regulatory genes, including those that regulate toxin production, and it needs to be investigated further. Autoinducers (AI-2) also have been implicated in the regulation of some toxin genes [51]. However,
in our strains, the production of AI-2 per cell unit, measured by the indicator Vibrio harveyi, was higher for 13124R than for ATCC 13124 and lower for NCTRR than for NCTR. The ratio of AI-2 production per OD unit in an overnight culture of the mutant to that of the wild type was 1.5 for ATCC 13124 and 0.14 for NCTR. The contradictory AZD0156 in vitro results observed in the transcription of various toxin genes in two resistant strains were accompanied by changes in the levels of toxins
and other enzymes. The most dramatic changes were observed for phospholipase C (PLC) and perfringolysin O (PFO). These two toxins were substantially decreased in 13124R and increased in NCTRR. The alterations in the production of enzymes were accompanied by changes in cytotoxicity for macrophages. The cytotoxicities of cell-free culture supernatants Ribociclib of the wild type ATCC 13124 and NCTR, for the macrophages were comparable. However, the cell-free culture supernatant of 13124R exhibited significantly lower cytotoxicity for macrophages than ATCC 13124, but that of NCTRR had higher cytotoxicity than NCTR. These data were consistent with the alterations in the transcription patterns of toxin genes and enzyme assays that were observed by DNA microarray analysis, qRT-PCR assay and toxin production. The cytotoxic effects were correlated with the transcription pattern of toxins and virulence-associated genes and enzymatic activities, confirming that the effect of fluoroquinolones on C. perfringens was strain-specific. O’Brien and Melville [33] reported that perfringolysin O (PFO) plays a more prominent role than α-toxin (PLC) in cytotoxicity for macrophages.