title: The response of the yeast Saccharomyces cerevisiae to sudden vs. gradual changes in environmental stress monitored by expression of the stress response protein Hsp12p.
abstract: The response of the yeast Saccharomyces cerevisiae to sudden vs. gradual changes in different environmental stress conditions during both respiratory growth and aerobic fermentative growth in the presence of excess glucose was investigated by monitoring the level and rate of expression of the stress response protein Hsp12p using the fluorescent fusion construct Hsp12p-Gfp2p. The initial expression level and the rate of Hsp12p synthesis was significantly greater under glucose-limited conditions in the chemostat (D<0.14 h(-1)) compared with when excess glucose was present in the auxostat. Decreasing the dilution rate and the glucose concentration further in the A-stat resulted in increased Hsp12p expression, which was more marked when a rapid rather than a gradual change was affected. Common stress factors such as NaCl, ethanol and elevated temperature caused stress responses in both D-stat and auxo-accelerostat culture. The magnitude of the stress response depended on the stress factor, cultivation conditions as well as the rate of change of the stress factor. The rate of Hsp12p synthesis increased due to all applied stresses, with the observed increase between 2 and 20 times lower when the stress was applied gradually rather than rapidly. The results suggested that the Hsp12p expression rate is a good indicator of applied stress in S. cerevisiae.
authors.affiliation: Competence Centre of Food and Fermentation Technologies, Akadeemia tee, Tallinn, Estonia. ildar.nisamedtinov@ttu.ee
authors.forename: Ildar
authors.initials: I
authors.lastname: Nisamedtinov
authors.forename: George G
authors.initials: GG
authors.lastname: Lindsey
authors.forename: Robert
authors.initials: R
authors.lastname: Karreman
authors.forename: Kerti
authors.initials: K
authors.lastname: Orumets
authors.forename: Mariane
authors.initials: M
authors.lastname: Koplimaa
authors.forename: Kaspar
authors.initials: K
authors.lastname: Kevvai
authors.forename: Toomas
authors.initials: T
authors.lastname: Paalme
mesh_terms: D003470:Culture Media; D000431:Ethanol / Q000378:metabolism; D005285:Fermentation; D015966:Gene Expression Regulation, Fungal; D005947:Glucose / Q000378:metabolism; D049452:Green Fluorescent Proteins / Q000235:genetics / Q000378:metabolism*; D006360:Heat-Shock Proteins / Q000235:genetics / Q000378:metabolism*; D018869:Heat-Shock Response; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism*; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000254:growth & development* / Q000378:metabolism / Q000502:physiology*; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000378:metabolism*; D012965:Sodium Chloride / Q000494:pharmacology; D013696:Temperature
chemical_list: D003470:Culture Media; C112591:HSP12 protein, S cerevisiae; D006360:Heat-Shock Proteins; D011993:Recombinant Fusion Proteins; D029701:Saccharomyces cerevisiae Proteins; D049452:Green Fluorescent Proteins; D000431:Ethanol; D012965:Sodium Chloride; D005947:Glucose