The effect of osmotic pressure on the membrane fluidity of Saccharomyces cerevisiae at different physiological temperatures.
Membrane fluidity in whole cells of Saccharomyces cerevisiae W303-1A was estimated from fluorescence polarization measurements using the membrane probe, 1,6-diphenyl-1,3,5-hexatriene, over a wide range of temperatures (6-35 degrees C) and at seven levels of osmotic pressure between 1.38 MPa and 133.1 MPa. An increase in phase transition temperatures was observed with increasing osmotic pressure. At 1.38 MPa, a phase transition temperature of 12 +/- 2 degrees C was observed, which increased to 17 +/- 4 degrees C at 43.7 MPa, 21+/- 7 degrees C at 61.8 MPa, and 24 +/- 9 degrees C at an osmotic pressure of 133.1 MPa. From these results we infer that, with increases in osmotic pressure, the change in phospholipid conformation occurs over a larger temperature range. These results allow the representation of membrane fluidity as a function of temperature and osmotic pressure. Osmotic shocks were applied at two levels of osmotic pressure and at nine temperatures, in order to relate membrane conformation to cell viability.
Laroche
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C
Laboratoire de Génie des Procédés Alimentaires et Biotechnologiques, ENSBANA, Dijon, France.
Beney
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L
Marechal
P A
PA
Gervais
P
P
D008560:Membrane Fluidity; D008565:Membrane Proteins / Q000737:chemistry; D008968:Molecular Conformation; D009997:Osmotic Pressure; D010743:Phospholipids / Q000737:chemistry; D012441:Saccharomyces cerevisiae / Q000502:physiology*; D013696:Temperature
D008565:Membrane Proteins; D010743:Phospholipids