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This work presents the results of an experimental study and of computer simulations concerning electric interactions in the surface layer of egg yolk lecithin (EYL) liposome membranes. The surface layer is formed by EYL polar heads, which possess features of electric dipoles, and positive charged polar heads belonging to admixtures of quaternary ammonium salts (AS). The results of the experimental...
Apoptosis is a genetically programmed phenomenon that aids in maintaining homeostasis in multicellular organisms. The characteristic morphological features of apoptosis are highly conservative and are dependent on the cell type and the apoptotic inducer. The nuclear events occurring during apoptosis include changes at the molecular level (i.e. DNA cleavage, modifications of nuclear polypeptides, and...
The plasma membrane is a specialised multi-component structure with inter- and intracellular signalling functions. Ca2+ plays a crucial role in cellular physiology, and an ATP-driven plasma membrane calcium pump (PMCA) plays the greatest role in the maintenance of a low free Ca2+ concentration in the cytoplasm. The enzyme is coded by four separate genes (PMCA 1-4), and, due to alternative splicing,...
Despite the fact that thioridazine is used clinically as a neuroleptic drug, little is known about the molecular mechanisms underlying its biological effects, in particular about its interactions with membranes. In the present work we investigate the influence of thioridazine on model and cell membranes, using calorimetry, DPH fluorescence polarization measurements, studies of haemolysis and scanning...
Ripple phase modelling was achievable by taking into consideration the dipole structure of the polar heads of model membrane molecules. Computer simulations enabled the selective analysis of a model membrane. Considering only the hydrophobic part of the lipid membrane, the gel-fluid transition stage can be obtained in such a simulation. Assuming an additional degree of freedom, the entire molecule...
The cell nucleus is separated from the rest of the cell by the nuclear envelope. The nuclear envelope, nuclear envelope proteins and nuclear lamina organise the structure of the entire nucleus and the chromatin via a myriad of interactions. These interactions are dynamic, change with the change (progress) of the cell cycle, with cell differentiation and with changes in cell physiology.
Since the physical interpretation of practical Kedem-Katchalsky equations is not clear, we consider an alternative, mechanistic approach to membrane transport generated by osmotic and hydraulic pressure. We study a porous membrane with randomly distributed pore sizes (radii). We postulate that the reflection coefficient (σp) of a single porę may equal 1 or 0 only. From this postulate we derive new...
The aim of this research was to characterize somaclonal variation in populations derived from embryos cultured on two types of induction medium (supplemented with either 2,4-D or dicamba), as well as to select and characterize several somaclonal lines. The sexual progenies of 40 R0 regenerants - A somaclones (derived on the medium with 2,4-D) and B somaclones (derived on the medium with dicamba) -...
Second messengers involved in the signal transduction pathway leading to induction of the plasminogen activator inhibitor (PAI-1) have not yet been well characterized. This study focuses on the mechanisms of regulation of PAI-1 expression by reactive oxygen species (ROS) in human endothelial cells. Inhibition of the tumor necrosis factor α (TNFα)-induced expression of PAI-1 by antioxidant N-acetyl-L-cysteine...
Dynamin - a member of the GTP-ase protein family - is essential for many intracellular membrane trafficking events in multiple endocytic processes. The unique biochemical features of dynamin - especially its propensity to assemble - enable severing the nascent vesicles from the membrane. The mechanism of dynamin’s action is still a subject of debate - whether it functions as a mechanochemical enzyme...
Dendrimers are globular, hyperbranched polymers possessing a high concentration of surface functional groups and internal cavities. These unique features make them very useful in many biomedical applications, especially as carrier molecules. In this study, the interaction of tryptophan and 1-anilinonaphthalene-8-sulfonic acid with three types of polyamidoamine dendrimers was examined. It was observed...
We studied the effect of the modification of focal adhesion kinase (FAK) on the growth, migration and adhesion of C3H 10T1/2 cells. Cells transfected with plasmid coding for antisense FAK displayed a low level of FAK protein. Interestingly, the transfected cells achieved a higher saturation density at confluence, and displayed reduced adhesion and enhanced emigration from a confluent layer of cells...
This review presents recent data about cell wall involvement in plant embryogenesis. During plant development, the cell wall is subjected to precise regulation. During this process a bidirectional information exchange between the cell wall and the protoplast is observed. The cell wall also mediates in the cell-cell (apoplastic) and cell to cell (symplastic) information flow. Especially some products...
A set of n-alkyl esters of N,N-dimethylglycine (DMG-n) and their methobromides (DMGM-n) was synthesized, and their activities on yeast Saccharomyces cerevisiae were compared. The compounds differ in the number of carbon atoms in the aliphatic chain. Aminoesters with 12 carbon atoms appeared to be most active. Unlike quaternary ammonium salts previously tested, the activities of the compounds were...
In the present study, the whole-cell patch-clamp technique was applied to elucidate modulatory effects of high-density lipoproteins (HDL), sphingosine (SPH), sphingosine-l-phosphate (SPP), lysophosphatidic acid (LPA) and sphingosyl- phosphorylcholine (SPC) on the activity of Kvl.3 channels in human T lymphocytes (TL). Obtained data provide evidence that application of SPC at micromolar concentrations...
The aim of the study was to examine a morphological picture of guinea pig skeletal muscles injected with neuropeptide Y (NPY), substance P (SP) or vasoactive intestinal peptide (VIP), to evaluate the influence of a single injection of the mentioned neuropeptides (NPS) on muscle morphology and mast cell, T lymphocyte and macrophage chemotaxis. There were different degrees of muscle fibre injuries as...
Plasma concentrations of natriuretic peptides increase in some pathological conditions, but very little is known about the effect of these vasodilator peptides on the regulation of the blood coagulation system. The fundamental role in the regulation of fibrinolysis is played by plasminogen activator inhibitor type 1 (PAI-1). Recent studies demonstrate that natriuretic peptides can modulate PAI-1 expression...
Lactoferrin (LF) is an iron-binding glycoprotein present in the cytoplasmic granules of neutrophils and in external secretions of mammals. Although the biological role of human and bovine lactoferrin has been extensively studied, there is still uncertainty as to the nature and function of lactoferrin receptors. We recently determined that methyl-α-D-mannopyranoside given intraperitoneally (i.p.) could...
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