title: Gene expression and phenotypic traits of Aggregatibacter actinomycetemcomitans in response to environmental changes.
abstract: OBJECTIVE
  Periodontopathogens experience several challenges in the oral cavity that may influence their transcription profile and resulting phenotype. This study evaluated the effect of environmental changes on phenotype and gene expression in a serotype b Aggregatibacter actinomycetemcomitans isolate.
  
  
  METHODS
  Cultures in early exponential phase and at the start of stationary growth phase in microaerophilic and anaerobic atmospheres were evaluated. Cell hydrophobic properties were measured by adherence to n-hexadecane; in addition, adhesion to, and the ability to invade, KB cells was evaluated. Relative transcription of 12 virulence-associated genes was determined by real-time reverse transcritption quantitative PCR.
  
  
  RESULTS
  The culture conditions tested in this study were found to influence the phenotypic and genotypic traits of A. actinomycetemcomitans. Cells cultured in microaerophilic conditions were the most hydrophobic, reached the highest adhesion efficiency and showed up-regulation of omp100 (which encodes an adhesion) and pga (related to polysaccharide synthesis). Cells grown anaerobically were more invasive to epithelial cells and showed up-regulation of genes involved in host-cell invasion or apoptosis induction (such as apaH, omp29, cagE and cdtB) and in adhesion to extracellular matrix protein (emaA).
  
  
  CONCLUSIONS
  Environmental conditions of different oral habitats may influence the expression of factors involved in the binding of A. actinomycetemcomitans to host tissues and the damage resulting thereby, and thus should be considered in in-vitro studies assessing its pathogenic potential.
authors.affiliation: Department of Microbiology, Institute of Biomedical Sciences, University of São Paulo, São Paulo, Brazil.
authors.forename: P L
authors.initials: PL
authors.lastname: Longo
authors.forename: A C R
authors.initials: AC
authors.lastname: Nunes
authors.forename: J E
authors.initials: JE
authors.lastname: Umeda
authors.forename: M P A
authors.initials: MP
authors.lastname: Mayer
mesh_terms: D016976:Aggregatibacter actinomycetemcomitans / Q000235:genetics* / Q000472:pathogenicity; D000473:Alkanes / Q000494:pharmacology; D017209:Apoptosis / Q000235:genetics; D001422:Bacterial Adhesion / Q000187:drug effects / Q000235:genetics; D001425:Bacterial Outer Membrane Proteins / Q000235:genetics; D001426:Bacterial Proteins / Q000235:genetics; D001427:Bacterial Toxins / Q000235:genetics; D001431:Bacteriological Techniques; D004777:Environment; D004847:Epithelial Cells / Q000382:microbiology; D016326:Extracellular Matrix Proteins / Q000235:genetics; D015964:Gene Expression Regulation, Bacterial / Q000235:genetics; D059647:Gene-Environment Interaction; D005838:Genotype; D006801:Humans; D007624:KB Cells / Q000382:microbiology; D009699:N-Glycosyl Hydrolases / Q000235:genetics; D010641:Phenotype; D011135:Polysaccharides, Bacterial / Q000235:genetics; D021122:Protein Subunits / Q000235:genetics; D014158:Transcription, Genetic / Q000235:genetics; D037521:Virulence Factors / Q000235:genetics
chemical_list: D000473:Alkanes; D001425:Bacterial Outer Membrane Proteins; D001426:Bacterial Proteins; D001427:Bacterial Toxins; D016326:Extracellular Matrix Proteins; C117494:Omp29 protein, Actinobacillus actinomycetemcomitans; D011135:Polysaccharides, Bacterial; D021122:Protein Subunits; D037521:Virulence Factors; C447141:cytolethal distending toxin, Actinobacillus actinomycetemcomitans; D009699:N-Glycosyl Hydrolases; C007932:n-hexadecane
keywords: Aggregatibacter actinomycetemcomitans; gene transcription; phenotypic traits; virulence factors