Search results for "Osmotic concentration"
showing 10 items of 21 documents
Involvement of osmotic cell shrinkage on the proton extrusion rate in Saccharomyces cerevisiae
2001
Saccharomyces cerevisiae has been subjected to hyperosmotic shocks by using permeating (sorbitol, xylitol, glycerol, NaCl) and nonpermeating (PEG 600) solutes. The proton extrusion rate decreased as the osmotic pressure increased, whichever solute was used. However, the total inhibition of the cellular H+ extrusion depended on the solute used. A total inhibition was observed at about 20 MPa with glycerol, xylitol and sorbitol. With PEG 600, a total inhibition of extracellular acidification was obtained at 8.5 MPa. NaCl, with an extracellular pressure of 37.8 MPa (near saturation), did not completely inhibit the extracellular acidification. These results showed that the total inhibition of p…
Response of the aging eye to first day of modern material contact lens wear
2018
Objectives: To investigate the ocular surface of an aged population wearing a daily disposable contact lens over their first day of wear. Methods: Forty eyes from forty presbyopic subjects were fitted a daily CL (Delefilcon A). Tear osmolarity, tear meniscus area (TMA) and ocular surface aberrations (total higher order root means square (RMS)) were assessed at baseline (t0), at 20 minutes (t1) and after 8 hours (t2) of wear. Fluorescein corneal and conjunctival staining and tear break up time (TBUT) were performed at t0 and t2. Results: No statistically significant changes were found between t0, t1 and t2 for TMA, and between t0 and t2 for fluorescein corneal and conjunctival staining. TBUT…
Yeast mRNA cap-binding protein Cbc1/Sto1 is necessary for the rapid reprogramming of translation after hyperosmotic shock.
2011
Global translation is inhibited in Saccharomyces cerevisiae cells under osmotic stress; nonetheless, osmostress-protective proteins are synthesized. We found that translation mediated by the mRNA cap-binding protein Cbc1 is stress-resistant and necessary for the rapid translation of osmostress-protective proteins under osmotic stress.
Influence of impregnation solution viscosity and osmolarity on solute uptake during vacuum impregnation of apple cubes (var. Granny Smith)
2008
Vacuum-assisted impregnation of pectinmethylesterase (PME) solution has been recognized as an efficient pretreatment to improve the firmness of heat-treated fruit. In order to improve the control of solute infusion into fruit pieces, the effect of the osmolarity and viscosity of vacuum impregnation solution on solute penetration and distribution was studied in 1.5 cm apple cubes, using model PME-based solutions containing sodium chloride and/or sodium alginate. While vacuum impregnation of either a viscous hypotonic or a non-viscous hypertonic solution infused solutes homogeneously into fruit pieces, the penetration of viscous hypertonic solutions was much lower, and PME or chloride infusio…
Rapid adaptation of signaling networks in the fungal pathogen Magnaporthe oryzae
2019
Abstract Background One fundamental question in biology is how the evolution of eukaryotic signaling networks has taken place. “Loss of function” (lof) mutants from components of the high osmolarity glycerol (HOG) signaling pathway in the filamentous fungus Magnaporthe oryzae are viable, but impaired in osmoregulation. Results After long-term cultivation upon high osmolarity, stable individuals with reestablished osmoregulation capacity arise independently from each of the mutants with inactivated HOG pathway. This phenomenon is extremely reproducible and occurs only in osmosensitive mutants related to the HOG pathway – not in other osmosensitive Magnaporthe mutants. The major compatible so…
Effect of Intraperitoneal Sterile Urine Injection on Abdominal Myoelectrical Activity in the Spinal Rat Model
1991
The abdominal muscle reflex contractions in response to intraperitoneal injection of homologous sterile urine and acid, alkaline, hypo- and hyperosmolar solutions are studied in an acute spinal rat model by conventional and integrated electromyographic techniques. Intraperitoneal injection of homologous sterile urine causes a powerful and almost immediate abdominal muscle contracture of relative short duration. This response seems not to be related to urine pH or osmolarity, since only when solutions with extreme variations in these parameters are injected intraperitoneally are significant abdominal muscle contractions observed.
Expression of Staphylococcus saprophyticus surface properties is modulated by composition of the atmosphere.
1995
Expression of two major surface proteins of Staphylococcus saprophyticus, the haemagglutinin and the Staphylococcus saprophyticus surface-associated protein (Ssp), requires carefully defined culture conditions. The Ssp is produced when bacteria are grown on agar, whereas expression of the haemagglutinin requires growth in broth. We sought to identify the environmental signals that are responsible for this modulation. Varying the pH, the osmolarity of the growth medium or the temperature did not influence expression of the proteins. In contrast, growth in an anaerobic atmosphere increased haemagglutination titres and fibronectin binding (both mediated by the haemagglutinin) but suppressed pr…
Accumulation of monoterpenes in shoot-proliferation cultures of Lavandula latifolia Med.
1993
Abstract We studied the effect of osmotic stress (induced by the addition of mannitol to the culture medium) and abscisic acid (ABA) addition on monoterpene accumulative capability in shoot proliferating cultures of Lavandula latifolia Med. The highest shoot elongation was achieved when the elongation medium contained sucrose (3%). Increasing the medium osmolarity or adding 25–50 μM ABA in shoot elongation cultures resulted in a significant increase in monoterpene accumulation in the regenerated shoots. These monoterpenes are qualitatively similar to those produced by the parent plants. Regulation of the conditions that limit the growth in shoot proliferation cultures of L. latifolia should…
Thermodynamics of yeast cell osmoregulation: Passive mechanisms
1996
International audience; The response of yeast cells to osmotic pressure variations of the medium were studied through the kinetics of cell-volume modifications corresponding to the mass transfer of water and solutes. Osmotic variations were made by modification of the concentration of an external binary solution (polyol/water) without nutritive components. Two phases were distinguished in the thermodynamic response. A transient phase following an osmotic shift, which is characterised by rapid water transfer across the cell membrane and whose kinetics determine cell viability; then, a steady-state phase is reached when the cell volume becomes quasi-constant. The response of the cell during t…
Nature of sterols affects plasma membrane behavior and yeast survival during dehydration.
2011
International audience; The plasma membrane (PM) is a main site of injury during osmotic perturbation. Sterols, major lipids of the PM structure in eukaryotes, are thought to play a role in ensuring the stability of the lipid bilayer during physicochemical perturbations. Here, we investigated the relationship between the nature of PM sterols and resistance of the yeast Saccharomyces cerevisiae to hyperosmotic treatment. We compared the responses to osmotic dehydration (viability, sterol quantification, ultrastructure, cell volume, and membrane permeability) in the wild-type (WT) strain and the ergosterol mutant erg6Δ strain. Our main results suggest that the nature of membrane sterols gover…