The experiments conducted on tonoplast of Beta vulgaris L. roots were performed to identify detergent-resistant lipid-protein microdomains (DRMs, interpreted as lipid rafts).The presence of DRMs can be found when dynamic clustering of sphingolipids, sterols, saturated fatty acids is registered, and the insolubility of these microdomains in nonionic detergents at low temperatures is proven. The elucidation of tonoplast microdomains has been based on results obtained with the aid of high-speed centrifuging in the sucrose gradient. The experiments have shown that tonoplast microdomains are rich in sphingolipids, free sterols and saturated fatty acids (such a lipid content is also typical of lipid-protein microdomains of other membranes), while only few phospholipids are present in tonoplast microdomains. The presence of microdomains has been confirmed by fluorescence and confocal microscopy using filipin and Laurdan as fluorescent probes. The experiments with Laurdan have shown that tonoplast microdomains are characterized by a high order compared to characteristics of the rest of the tonoplast. Thus, the presence of detergent-resistant lipid-protein microdomains in the tonoplast has been demonstrated.

No abstract

To study the characteristics of the structure and the functional role of chloroplast membranes of halophytes with different salt tolerance strategy, raft structures were isolated. Lipid analysis data provided evidence for the presence of rafts in the chloroplast membranes. The discovered significant differences in the content of raft-forming lipids in different halophytes suggest a relationship between the functions of rafts and the mechanisms of salt tolerance in plants.

In the present work, we studied detergent-resistant membrane microdomains (DRM) of chloroplasts and mitochondria – organelles that provide photosynthesis and respiration in a plant cell. The objects of the study were euhalophyte Salicorniaperennans Willd., which relates to salt-accumulating plants and glycohalophyte Artemisia santonica L., which relates to salt-excluder plants. To get DRM, the chloroplast and mitochondria fractions were solubilised with a solution containing Triton X-100. The resulting material was introduced in sucrose gradient of 35–25–15–5% and centrifuged at 200000 g, 2 h. The presence of an opalescent detergent-resistant zone of membranes in 15% sucrose layer and a specific lipid composition of this zone were the signs of successful rafts obtaining of. The isolated DRM are sterol- and cerebroside-enriched (27–89% of the sum of membrane lipids) domains with a high degree of saturation of fatty acids composition (more than 50% of the sum). The main DRM-specific lipids of chloroplast of A. santonica glycohalophyte are cerebrosides, whereas those of S. perennans euhalophyte are sterols. The revealed differences in the composition of raft-forming lipids in chloroplast and mitochondria halophyte membranes, differing in the salt-resistance strategy, suggest the participation of rafts in salt-resistance mechanisms.

<p class="Default"><strong> </strong></p><p class="Default">The effect of 2,6-dipyridinium selenabicyclo[3.3.1]nonandibromide (996 zh) on the level of lipid peroxidation (LPO), on the activity of glutathione reductase (GR) and on the morphometric parameters of oilseed radish seedlings under normal conditions and under stress (200 mmol NaCl) has been studied. It has been established that the substance 996 zh at a concentration of 100 μm exerted an antioxidant effect reducing the level of lipid peroxidation and increasing the activity of GR. In connection with that the germinating ability of seeds and the biomass of the roots and stems of seedlings increased, both under normal conditions and under stress conditions.</p><p class="Default">The concentration of the substance 996 zh of 1000 μmol had a toxic effect, increasing the LPO level in normal conditions, but neutralized the effect of stress due to the addition of NaCl. This concentration had a slight inhibitory effect on germinability and on root development in seedlings. However, the same concentration of the substance 996 zh (1000 μmol) had a positive effect on the development of shoots under both normal and stressed conditions.</p>