cDNA-Shigella flexnerri- Furazolidone

Shigella flexneri is a facultative intracellular pathogen which is mainly responsible for endemic shigellosis in developing countries. In the present study, we demonstrated S.flexnerri was susceptible to furazolidone, a nitrofuran derivative that has been used as therapeutic regimen against a variety of gastro-intestinal bacterial infections. To identify the global transcriptional responses of S.flexnerri in response to furazolidone treatment, S.flexnrri was exposed to both subinhibitory and inhibitory concentrations of furazolidone and microarray analysis was used to examine gene expressions after both short and long period of incubation. Analysis of microarray data revealed that genes involved in soxRS and oxyR regulons, iron metabolism, DNA replication and repair and lipid peroxidation were induced by the drug, while a large percentage of genes involved in energy production, carbohydrate metabolism, amino acid metabolism, and lipid metabolism were significantly repressed after the drug treatment. In addition, many genes related to preventing against injuries of iron-sulfur clusters known to be caused by superoxide radicals were also up-regulated. These data establish potential for furazolidone to enhance free radical reactions through its reductive activation, which indicates oxidative damages may be implicated in antibacterial effect of the drug. Keywords: drug expressional profiles Overnight cultures were diluted in freshly prepared cation-adjusted MHB to optical density at 600 nm (OD600) of about 0.05.Then the diluted cultures were allowed to continue growing at 37°C with shaking (200 rpm).When they were grown to early exponential growth phase (an OD600 of about 0.3), furazolidone was added from the 400×stock dissolved in DMSO into the cultures to give final concentrations of 0.25× ,0.5× or 1× minimum inhibitory concentration (MIC). Thus the final concentration of solvent (DMSO) in every test was 0.25% (vol/vol). Meanwhile, DMSO without the antimicrobial was added to control cultures at a final concentration of 0.25% (vol/vol) .At 30 and 90 min after treatment, samples were collected and washed twice with PBS for subsequent RNA isolation. Therefore, we established six test conditions altogether. In order to prepare biological replicates for RNA isolation, the experiment was independently performed three times. Altogether, there are 18 samples in our study.