Objectives: The aim of the study was to investigate the Campylobacter jejuni response to subinhibitory concentrations of natural antimicrobial compound pinocembrin
Overall design: Influence of pinocembrin on gene expression in C. jejuni NCTC 11168 was determined by expressional analysis and qRT-PCR. Exponential phase culture was adjusted to OD600=0.2 in MHB using spectrophotometer (Smart Spec, Bio-Rad, Hercules, CA, USA). Five ml of culture was treated with 16 mg/l pinocembrin dissolved in DMSO. Only DMSO (0.048 %) was added to untreated samples. Cultures were treated for 2 h, incubated microaerobically shaking (160 rpm) at 42°C. Experiments were carried out in 4 biological replicates. RNA Protect Bacteria reagent (Qiagen, Maryland, USA) was added to the culture and total RNA was isolated using RNeasy mini kit (Qiagen) and treated with Ambion® Turbo DNA-freeTM kit (Invitrogen, USA).
Microarrays with 4751 probes targeting 1756 genes specific for Campylobacter jejuni subsp. jejuni NCTC 11168 (Mycroarray, Biodiscovery-LLC, MI, USA) were used for gene expression analysis. The cDNA was synthesized with random hexamers, SuperScriptTM III Reverse Transcriptase and amynoallyl dUTP (all supplied by Invitrogen, USA) and labeled with monofunctional NHS-ester dye Amersham C3 or Cy5 (GE Healthcare, Buckinghamshire, UK). Concentration of cDNA and labeling efficiency was determined spectrophotometrically with NanoDrop 1000. Four biological replicates were hybridized to four microarrays according to manufacturer’s protocol, incubated for 24 hours at 42⁰C and scanned at 550 nn for Cy3 and 650 nm for Cy5 with General Scanning ScanArray 5000 (PerkinElmer, Boston, USA). Flourescence intensities were converted to digital signal with ImaGene software (BioDiscovery, EI Segundo, USA).
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