title: Effect of γ-irradiation on gene expression of heat shock proteins in the foodborne pathogen Escherichia coli O157:H7.
abstract: OBJECTIVE
  The expression levels of seven genes (clpB, dnaK, groES, grpE, htpG, htpX and ibpB) encoding heat shock proteins (HSP) in Escherichia coli O157:H7 (E. coli) gamma irradiated was investigated. Timing impact of post-irradiated RNA extraction on the expression levels of these seven genes was also studied at a dose damaging the bacterial cells (0.4 kGy).
  
  
  METHODS
  Bacterial samples were γ-irradiated at 0.4 kGy and at a lethal dose of 1.3 kGy. RNA was extracted at 0 min post irradiation for both irradiation doses and at 15, 30, 60, 90 or 120 min post-irradiation at the dose damaging the cells. Quantification of the gene expression was performed using quantitative real-time polymerase chain reaction (q-RT-PCR).
  
  
  RESULTS
  The expression of genes encoding HSP was a very dynamic process evolving rapidly when E. coli cells were irradiated at 0.4 kGy. Notably, groES, grpE and ibpB were more up- regulated at 1.3 kGy than those at 0.4 kGy.
  
  
  CONCLUSIONS
  For the seven genes studied there were more damaged proteins during irradiation at the lethal dose and this dose causes increased expression in HSP which contributes to damage reparation. Expression patterns of genes encoding HSP in E. coli treated by γ-irradiation are different from those treated by heat shock.
authors.affiliation: Research Laboratory in Sciences Applied to Food, Canadian Irradiation Center, INRS-Institut Armand-Frappier , Laval, Quebec.
authors.forename: Karine
authors.initials: K
authors.lastname: Trudeau
authors.forename: Khanh Dang
authors.initials: KD
authors.lastname: Vu
authors.forename: Éric
authors.initials: É
authors.lastname: Déziel
authors.forename: François
authors.initials: F
authors.lastname: Shareck
authors.forename: Monique
authors.initials: M
authors.lastname: Lacroix
mesh_terms: D015169:Colony Count, Microbial; D017931:DNA Primers / Q000235:genetics; D004307:Dose-Response Relationship, Radiation; D019453:Escherichia coli O157 / Q000235:genetics* / Q000528:radiation effects*; D029968:Escherichia coli Proteins / Q000378:metabolism; D005514:Food Irradiation; D005516:Food Microbiology; D005720:Gamma Rays; D020869:Gene Expression Profiling; D015964:Gene Expression Regulation, Bacterial / Q000528:radiation effects*; D006360:Heat-Shock Proteins / Q000378:metabolism*; D060888:Real-Time Polymerase Chain Reaction; D013234:Stem Cells; D013997:Time Factors
chemical_list: D017931:DNA Primers; D029968:Escherichia coli Proteins; D006360:Heat-Shock Proteins