Regulation of intracellular osmotic pressure during the initial stages of salt stress in a salt-tolerant yeast, Zygosaccharomyces rouxii.
The accumulation of glycerol and inorganic ions as it related to osmotic pressure, and the regulation of intracellular osmotic pressure in a salt-tolerant yeast, Zygosaccharomyces rouxii, were examined for several hours after salt stress. Intracellular contents of glycerol increased for up to 6 h in media supplemented with 1 M and 2 M NaCl and did not increase in medium containing 3 M NaCl. Intracellular contents of Na+ and Cl- reached a maximum value within 1 and 3 h, respectively, in all NaCl-containing media and increases were proportional to the concentration of NaCl in the medium. As glycerol was accumulated in cells, the intracellular contents of Na+ and Cl- gradually decreased in media containing 1 M and 2 M NaCl. After salt stress, cell volume decreased within 1 h and the original volume was re-established for 3 to 6 h in media with 1 M and 2 M NaCl but not in medium with 3 M NaCl. Intracellular concentrations of solutes, which were calculated from the total contents of glycerol and inorganic ions and the cell volume, became almost equivalent to the external osmotic pressure within 1 h after salt stress. Experiments using various inhibitors showed that a large amount of ATP was required not only for the synthesis and accumulation of glycerol but also for the exclusion of Na+ and Cl- from cells under salt-stressed conditions.
Yagi
T
T
Department of Biology, Faculty of Science, Osaka City University, Japan.
D003470:Culture Media; D004573:Electrolytes / Q000378:metabolism; D005990:Glycerol / Q000378:metabolism; D009997:Osmotic Pressure; D004718:Saccharomycetales / Q000187:drug effects / Q000378:metabolism*; D012965:Sodium Chloride / Q000494:pharmacology*; D015003:Yeasts / Q000187:drug effects / Q000378:metabolism*
D003470:Culture Media; D004573:Electrolytes; D012965:Sodium Chloride; D005990:Glycerol