The study of the functional state of lipid rafts in the cytoplasmic membrane of Pisum Sativum seedlings under clinorotation

The results of cytological, biochemical, and molecular biological studies clearly demonstrate the significant influence of microgravity on the main processes of plant development, revealing the mechanisms which underlie the reactions of plant responses to microgravity and ensure their adaptation to this factor. The key role in cell function belongs to the cytoplasmic membrane (CM). First of all, by its qualities and functions, it can play an important role in the adaptation of plants to microgravity. However, data about the effect of altered gravity on the physicochemical properties of CM are limited. Recently, much attention has been paid to the study of functional microdomains of the lipid bilayer that have a specific localization and content of lipids and proteins - lipid rafts. They are defined as a dynamic nanosized, sterol- and sphingolipid-enriched ordered association of specific proteins, in which a metastable resting state can be activated by a combination of specific lipid-lipid, protein-lipid, and protein-protein interactions. There are more and more experimental data that confirm their participation in such live processes as endocytosis, apoptosis, internalization of toxins, bacteria, viruses, etc., as well as their important role in the protective mechanisms of the cell under different stressors. In this work, a fluorescent marker of sterols – filipin and a fluorescent probe laurdan were used to confirm the presence of cholesterol and sphingolipid-enriched lipid ranges in CM. Our results regarding the increase in generalized polarization in the clinorotation conditions correlate with the data obtained in previous studies and indicate the sensitivity of the CM to a longer action of the clinorotation.