title: Expression variability of co-regulated genes differentiates Saccharomyces cerevisiae strains.
abstract: BACKGROUND
  Saccharomyces cerevisiae (Baker's yeast) is found in diverse ecological niches and is characterized by high adaptive potential under challenging environments. In spite of recent advances on the study of yeast genome diversity, little is known about the underlying gene expression plasticity. In order to shed new light onto this biological question, we have compared transcriptome profiles of five environmental isolates, clinical and laboratorial strains at different time points of fermentation in synthetic must medium, during exponential and stationary growth phases.
  
  
  RESULTS
  Our data unveiled diversity in both intensity and timing of gene expression. Genes involved in glucose metabolism and in the stress response elicited during fermentation were among the most variable. This gene expression diversity increased at the onset of stationary phase (diauxic shift). Environmental isolates showed lower average transcript abundance of genes involved in the stress response, assimilation of nitrogen and vitamins, and sulphur metabolism, than other strains. Nitrogen metabolism genes showed significant variation in expression among the environmental isolates.
  
  
  CONCLUSIONS
  Wild type yeast strains respond differentially to the stress imposed by nutrient depletion, ethanol accumulation and cell density increase, during fermentation of glucose in synthetic must medium. Our results support previous data showing that gene expression variability is a source of phenotypic diversity among closely related organisms.
authors.affiliation: RNA Biology Laboratory, CESAM & Department of Biology, Universidade de Aveiro, Portugal.
authors.forename: Laura
authors.initials: L
authors.lastname: Carreto
authors.forename: Maria F
authors.initials: MF
authors.lastname: Eiriz
authors.forename: Inês
authors.initials: I
authors.lastname: Domingues
authors.forename: Dorit
authors.initials: D
authors.lastname: Schuller
authors.forename: Gabriela R
authors.initials: GR
authors.lastname: Moura
authors.forename: Manuel A S
authors.initials: MA
authors.lastname: Santos
mesh_terms: D000431:Ethanol / Q000378:metabolism; D020869:Gene Expression Profiling; D015966:Gene Expression Regulation, Fungal; D005800:Genes, Fungal; D005947:Glucose / Q000378:metabolism; D005810:Multigene Family; D009584:Nitrogen / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000235:genetics* / Q000378:metabolism; D013312:Stress, Physiological / Q000235:genetics
chemical_list: D000431:Ethanol; D005947:Glucose; D009584:Nitrogen