title: Genome-wide expression profiling of the osmoadaptation response of Debaryomyces hansenii.
abstract: The euryhaline marine yeast Debaromyces hansenii is a model system for the study of processes related to osmoadaptation. In this study, microarray-based gene expression analyses of the entire genome of D. hansenii was used to study its response to osmotic stress. Differential gene expression, compared to control, was examined at three time points (0.5, 3 and 6 h) after exposure of D. hansenii cultures to high salt concentration. Among the 1.72% of genes showing statistically significant differences in expression, only 65 genes displayed at least three-fold increases in mRNA levels after treatment with 2 M NaCl. On the other hand, 44 genes showed three-fold repression. Upregulated as well as the downregulated genes were grouped into functional categories to identify biochemical processes possibly affected by osmotic stress and involved in osmoadaptation. The observation that only a limited number of genes are upregulated in D. hansenii in response to osmotic stress supports the notion that D. hansenii is pre-adapted to survive in extreme saline environments. In addition, since more than one-half of the upregulated genes encode for ribosomal proteins, it is possible that a translational gene regulatory mechanism plays a key role in D. hansenii's osmoregulatory response. Validation studies for ENA1 and for hyphal wall/cell elongation protein genes, using real-time PCR, confirmed patterns of gene expression observed in our microarray experiments. To our knowledge, this study is the first of its kind in this organism and provides the foundation for future molecular studies assessing the significance of the genes identified here in D. hansenii's osmoadaptation.
authors.affiliation: Department of Marine Sciences, University of Puerto Rico, Mayagüez, Puerto Rico.
authors.forename: Nancy Arroyo
authors.initials: NA
authors.lastname: Gonzalez
authors.forename: Adrinel
authors.initials: A
authors.lastname: Vázquez
authors.forename: Humberto G
authors.initials: HG
authors.lastname: Ortiz Zuazaga
authors.forename: Arup
authors.initials: A
authors.lastname: Sen
authors.forename: Hugo Luna
authors.initials: HL
authors.lastname: Olvera
authors.forename: Sandra
authors.initials: S
authors.lastname: Peña de Ortiz
authors.forename: N S
authors.initials: NS
authors.lastname: Govind
mesh_terms: D000222:Adaptation, Physiological; D055165:Debaryomyces / Q000187:drug effects / Q000235:genetics / Q000502:physiology*; D005656:Fungal Proteins / Q000235:genetics / Q000378:metabolism; D020869:Gene Expression Profiling; D015966:Gene Expression Regulation, Fungal; D016681:Genome, Fungal; D018869:Heat-Shock Response; D008969:Molecular Sequence Data; D020411:Oligonucleotide Array Sequence Analysis / Q000379:methods*; D009997:Osmotic Pressure; D012965:Sodium Chloride / Q000494:pharmacology
chemical_list: D005656:Fungal Proteins; D012965:Sodium Chloride