卷 40, 编号 2 (2023)

The influence of perfluorocarbon (PFС) nanoparticles on functioning of blood cells is considered. Emulsified PFC nanoparticles in small volumes affect the gas transport function of the blood by increasing the rate of oxygen diffusion from erythrocytes to tissues. PFC nanoparticles were found to affect blood cells (erythrocytes, leukocytes, platelets) in a dose-dependent manner. It is assumed that depending on the emulsion dose, i.e., the density of nanoparticles in the surrounding milieu, the response of the cell receptor apparatus can cause activation or deterioration of the cell functioning.

In this work we investigated the electron transport processes in chloroplasts of two contrasting species of Tradescantia, the shade-tolerant species T. fluminenesis and the light-loving species T. sillamontana, grown under moderate or strong light conditions. Plants were acclimated to a moderate or high intensity of photosynthetically active radiation. Photochemical activity of Photosystem 2 (PS2) was assayed by measuring chlorophyll a (Chl a) fluorescence, using the OJIP test, and by monitoring a slow induction of Chl a fluorescence (SIF) in Tradescantia leaves in vivo and in situ. The coefficient of non-photochemical quenching (NPQ) of Chl a fluorescence was determined from the SIF kinetics. Photochemical activity of photosystem 1 (PS1) was determined by electron paramagnetic resonance from the light-induced redox transients of P700, photoreaction center of PS1. Shade-tolerant (T. fluminenesis) and light-loving (T. sillamontana) species showed clear differences in their photosynthetic characteristics depending on long-term (up to 5 months) acclimatization to moderate (50–125 µmol photons m^–2 s^–1) or strong (850–1000 µmol photons m^–2 s^–1) irradiation with photosynthetically active white light. In the leaves of light-loving species T. sillamontana, the photosynthetic characteristics changed only slightly upon variations of light intensity. Leaves of the shade-tolerant species T. fluminenesis exhibited a pronounced sensitivity to changes in light intensity during acclimatization, showing a reversible increase in NPQ accompanied by an attenuation of PS2 photochemistry. After the reduction of light intensity, photochemical activity of PS2 recovered.

One of the key receptors on the surface of platelets, non-nuclear cells responsible for preventing blood loss when blood vessels are damaged, is the receptor for the extracellular matrix protein collagen, glycoprotein VI (GPVI). GPVI triggers tyrosine kinase signaling in platelets, simultaneously initiating calcium signaling via phospholipase Cγ2 (PLCγ2) and phosphoinositide signaling via phosphoinositide-3-kinase (PI3K). Previously, our group demonstrated that among healthy donors there is more than a twofold variability in calcium response to activation through the GPVI receptor. Here, a computer model of platelet activation through the GPVI receptor is proposed to explain this phenomenon. This model is a system of ordinary differential equations integrable by the LSODA method. The model equations were derived from a previously published model of platelet activation via the CLEC-2 receptor. Using the developed model, a monotonic dependence of the degree of platelet activation on the number of GPVI receptors was predicted. An analysis of the sensitivity of the model to its parameters showed that the platelet response to activation through GPVI is determined by the number of GPVI receptors, as well as the catalytic parameters of tyrosine kinases, while a twofold change in the number of receptors is sufficient to explain the observed phenomenon. Thus, it was theoretically predicted that the variability of calcium responses of platelets to their stimulation through the GPVI receptor could be determined by the variability in the number of GPVI receptors on the platelet surface of healthy donors.

This work is aimed to develop a number of cationic amphiphiles based on amino acid derivatives of diethanolamine as potentially membrane-active antibacterial agents. The developed compounds contain two amino acid residues in the polar block and various length of aliphatic chains in the hydrophobic domain. Amphiphiles were obtained in preparative amounts sufficient to confirm their structures and perform a study of antibacterial activity. The synthesized samples based on β-Ala (4c) and GABA (4d) with an aliphatic C12 chain in the hydrophobic domain showed a promising level of antimicrobial activity (minimal inhibitory concentration, MIC, 1 μg/mL) against gram-positive (B. subtilis) and gram-negative (E. coli) bacteria. Amphiphiles containing aromatic amino acids L-Phe (6a) and L-Trp (6b) in the polar head group and C8 hydrocarbon chain are active against B. subtilis with a MIC of 1 μg/mL. The obtained data on antimicrobial activity make the selected compounds attractive for further detailed study of their mechanism of action.

A variety of surface receptors and intracellular signaling systems are involved in cell-to-cell communication and paracrine/autocrine regulation of cellular functions. Being most numerous, the family of G-protein coupled receptors (GPCRs) is involved in the regulation of almost all physiological processes due to coupling to multiple and diverse intracellular signaling cascades. Among them, the ubiquitous players are the adenylate cyclase cascade, which controls the intracellular cAMP level, and the phosphoinositide cascade, which determines many aspects of intracellular Ca²⁺ signaling. Certain facts suggest that the adenylate cyclase and phosphoinositide cascades can be cross regulated. It therefore can be expected that agonists of adenylate cyclase-coupled GPCR receptors also might affect intracellular Ca²⁺, and in turn, Ca²⁺-mobilizing ligands might initiate a change in the cAMP level. Thus, simultaneous monitoring of cAMP and Ca²⁺ in the cell cytosol appears to be rational, as it can significantly refine the understanding of signaling processes initiated by agonists. The on-line monitoring of intracellular cAMP is currently possible only with the use of genetically encoded sensors; such sensors have also been developed for the analysis of intracellular Ca²⁺ signals. Here we generated a monoclonal line HEK-293 co-expressing molecular fluorescent sensors for cAMP (Pink Flamindo) and Ca²⁺ (GEM-GECO1). Physiological tests showed that this cell line provides the possibility of simultaneous monitoring of cAMP and Ca²⁺ with sufficient sensitivity. Such a tool can increase the efficacy of studying agonist-induced intracellular processes and, in particular, the analysis of crosstalk between the cAMP and Ca²⁺ signaling systems.