Search results for "Osmotic"
showing 10 items of 156 documents
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…
Uptake of an Endocytic Marker by Rice Cells: Variations Related to Osmotic and Saline Stress
2003
Saline and osmotic stress are the main abiotic factors limiting the productivity of rice and other crop plants. Although both coincide in generating water deficit and affect many aspects of plant growth and development similarly, some effects of salinity are distinctively related to the ionic component of salt stress. At the cellular level, dessication tolerance is largely dependent on the cell's ability for osmotic adjustment. Here, we have studied the effects of saline and osmotic stress on endocytosis by rice cells, to investigate the common and distinctive effects of saline-generated stress and osmotically generated stress, and the possible involvement of endocytosis in tolerance mechan…
Nitric oxide production in tobacco leaf cells: a generalized stress response?
2003
The function of nitric oxide (NO), a gaseous free radical emitted by many plants, is incompletely understood. In the present study the hypothesis that NO generation, like that of the reactive oxygen species, occurs as a general response to different environmental cues was tested. Leaf peels and mesophyll cell suspensions of Nicotiana tabacum cv. Xanthi were loaded with the NO-specific fluorophore, diaminofluorescein, and subjected to an abiotic stressor. Light stress and mechanical injury had no apparent effect on NO production. In contrast, high temperatures, hyperosmotic stress, salinity and epi-illumination in a microscope all led to rapid surges in NO-induced fluorescence. The fluoresce…
The Determination of Carbohydrates by High-Performance Anion-Exchange Chromatography Coupled with Pulsed Amperometric Detection (HPAEC-PAD)
2021
Chromatography techniques are widely used to separate, identify, and quantify molecules depending on their physicochemical properties. Standard methods range from simple size exclusion to separation based on affinity or ion exchange. Here, we present a method for the direct analysis of carbohydrates in Magnaporthe oryzae using high-performance anion-exchange chromatography (HPAEC) coupled with pulsed amperometric detection (PAD). The combination of HPAEC with PAD provides the highest selectivity and sensitivity with minimal sample preparation and cleanup time. Utilizing our HPAEC-PAD approach, we obtain reliable and highly reproducible determination of carbohydrates produced as osmotic stre…
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…
Insight into the primary mode of action of TiO2 nanoparticles on Escherichia coli in the dark.
2015
16 pages; International audience; Large-scale production and incorporation of titanium dioxide nanoparticles (NP-TiO2 ) in consumer products leads to their potential release into the environment and raises the question of their toxicity. The bactericidal mechanism of NP-TiO2 under UV light is known to involve oxidative stress due to the generation of reactive oxygen species. In the dark, several studies revealed that NP-TiO2 can exert toxicological effects. However, the mode of action of these nanoparticles is still controversial. In the present study, we used a combination of fluorescent probes to show that NP-TiO2 causes Escherichia coli membrane depolarization and loss of integrity, lead…
Impact of relative air humidity fluctuations on the survival of Listeria monocytogenes : application to improve hygiene in food processing environment
2016
Environmental hydration fluctuations influence microorganism viability and activity. The air relative humidity (RH) is a potentially effective parameter to control the development and the persistence of pathogenic microorganisms. However, efficiency of this parameter remains not well characterized compared to others environmental factors such as pH or temperature. Drying is the final step of cleaning and disinfection processes used in the food industry. However, if this process is empirically used, it could also be used to improve the decontamination of surfaces in premises and reduce the persistence of microorganisms. Despite cleaning and disinfection, Listeria monocytogenes is commonly fo…
Characterization of pressure retarded osmosis lab-scale systems
2016
Power generation from salinity gradient is a viable alternative to produce energy from renewable sources. Pressure Retarded Osmosis (PRO) is one of the technologies proposed so far for the exploitation of such energy source. In the present preliminary work, two different geometry modules were tested under atmospheric pressure (i.e. forward osmosis or depressurized-PRO conditions). The first one is a conventional planar geometry cell. The second is a customized cylindrical membrane module, able to mechanically support the osmotic membrane along with the spacers. The latter, thanks to its design, allows membranes and spacers to be easily changed for testing purposes. A novel simplified proced…
Molekülgrößenbestimmungen an makromolekularen Stoffen (Kritik und Vergleich der Methoden)
1952
A survey is given of the most important methods for determination of molecular weight (osmotic pressure, ultracentrifuge and diffusion, light scattering, viscosity). All the methods require an extrapolation to zero concentration in order to use equations valid for ideal solutions. Furthermore the polymolecularity of the examined substance must be considered, since each method yields a characteristic average of molecular weight differing from the others. The present limits of the methods are given and their results compared.