Effect of hypoxia on porphyrin metabolism in bone marrow mesenchymal stem cells.

Under hypoxic conditions, aminolevulinic acid-induced accumulation of porphyrin pigments and increase in heme content was observed in bone marrow mesenchymal stem cells. The expression of transferrin receptor CD71 responsible for Fe(2+) transport into the cell was also enhanced. Blockade of porphyrin-transporting protein ABCG2 with fumitremorgin C under conditions of normoxia and hypoxia induced accumulation of porphyrin pigments; in hypoxia, these changes were more pronounced.

[Silver nanoparticles induce lipid peroxidation and morphological changes in human lymphocytes surface].

To evaluate toxicity of silver nanoparticles synthesized by using the reverse micelle formation method, the effects of nanoparticles on lipid peroxidation and morphological changes of cell membranes in human lymphocytes were studied. It was found that under the influence of nanoparticles a reduction in cell viability and formation of excessive levels of reactive oxygen species were observed. Silver nanoparticles at different concentrations activate the processes of lipid peroxidation and, as a consequence, led to morphological changes in human lymphocytes.

[Conformationally stable segments in helical structures of polypeptide chains of proteins and their role in high level structures formation].

In the work the arguments are presented in favor of the idea on the role of conformationally stable oligo-peptides in specific long-distance interactions in phenomena of molecular recognition during various biological processes. Original authors' and literature data are taken into account. The examples of conformationally stable short oligopeptides participation in alpha-helix and collagen type structures formation are given simultaneously with theoretical approaches. The conformationally stable oligopeptides obtained in the course of PDB bank analysis are discussed. The role of amino acids sequence in collagen helix formation is shown.

[ROS induction and structural modification in human lymphocyte membrane under the influence of carbon nanotubes].

To assess the potential risks of using the artificial nanostructures the structural state of the human lymphocyte membrane and lipid peroxidation under the influence of multi-walled carbon nanotubes with metal impurities was studied. The ability of carbon nanotubes to induce the formation of reactive oxygen species in cells was examined. A dose-dependent increase in reactive oxygen species formation in lymphocytes, which was not registered in cells pre-incubated with N-acetylcystein, after exposure to carbon nanotubes was shown. The addition of iron chelator deferoxamine to carbon nanotubes has also resulted in a decrease of reactive oxygen species. The mechanism of the activation of lipid peroxidation under the influence of carbon nanotubes and a structural modification of human lymphocyte membranes were discussed.

[Interconnection between architecture of protein globule and disposition of conformational conservative oligopeptides in proteins from one protein family].

It was shown that selective interactions between helical segments of macromolecules can realize in globular proteins in the segments characterized by the same periodicities of charge distribution i.e. between conformationally conservative oligopeptides. It was found that in the macromolecules of alpha-helical proteins conformationally conservative oligopeptides are disposed at a distance being characteristic of direct interactions. For representatives of many structural families of alpha-type proteins specific disposition of conformationally conservative segments is observed. This disposition is inherent to a particular structural family. Disposition of conformationally conservative segments is not related to homology of the amino acid sequence but reflects peculiarities of native 3D-architectures of protein globules.

[Role of calcium ions in photosignaling processes in a plant cell].

Ca2+ is an important structural and functional component of plant cells. During the last decade, Ca2+ attracted attention as a secondary messenger in signaling processes in plants to mediate the action of abiotic and biotic signals including light. The structural basis for Ca2+ signaling in plants, the generation of Ca2+ signatures and of nature of Ca2+ sensors are considered in relation to the functioning of plant photoreceptors phytochromes, cryptochromes, and phototropins. Special attention was focused upon genetic factors controlling the expression of light-inducible genes being closely related to above photoreceptors. The analysis of the achievements in the field of plant photoreceptor signal transduction and suggestions of some prospects for the future research were done.

[Transgenic Belarussian-bred potato plants expressing genes for antimicrobial peptides of the cecropin-melittin type].

Binary vectors for Agrobacterium-mediated transformation were constructed to express the genes for antimicrobial peptides (APs) of the cectropin-melittin type under the control of the cauliflower mosaic virus 35S RNA promoter in plants. It was shown with Escherichia coli and Agrobacterium tumefaciens cells that the cassettes could be cloned in pB1121-based vectors with deletion of the 3-D-glycuronidase gene only in the orientation opposite to that of the original vector. Transgenic potato plants were obtained using the Belarussian varieties Odyssey, Vetraz, and Scarb. Their cells expressed the MsrA1 or CEMA peptides of the cecropin-melittin type. The expression was shown to confer higher resistance to bacterial (Erwinia carotovora) infection and extremely high resistance to fungal (Phytophtora infestans and Alternarla solani) infections.

[Effect of the stem cell factor on the morphology and functional state of mouse embryonic stem cells].

The effect of the stem cell factor on the state of membranes and functional activity of mouse embryonic stem cells cultivated in LIF (Leukemia Inhibitory Factor) cytokine-free and LIF-containing media has been studied. It was shown that the stem cell factor induces changes in the viscosity of membrane lipid bilayer and increases the respiration rate, the ATP level, and the proliferation activity of embryonic stem cells. An intricate character of the LIF-dependent modification of biological effects of the stem cell factor was revealed.

[Cloning and analysis of coding cDNA sequence of human lymphocyte Csk tyrosine kinase under normal conditions and in choroidal melanoma].

The main function of Csk tyrosine kinases is phosphorylation of the C-terminal part of Srk tyrosine kinases as a mechanism of their downregulation. A decrease in the expression of csk gene results in the enhancement of Srk tyrosine kinase activity. In this study, cDNA containing the full coding sequence of the human leukocyte Csk tyrosine kinase gene has been cloned. The protein encoded by a a 1624-bp cDNA fragment has 99% homology to human Csk tyrosine kinase. A comparative sequence analysis of full-length cDNAs for Csk tyrosine kinase of normal lymphocytes and lymphocytes of patients with choroidal melanoma revealed a nucleotide substitution in dexon 10 of the gene, which appears to be of diagnostic significance. It has been shown that the risk of choroidal melanoma correlated with the frequency of this allele.

[Obtaining a full-length encoding cDNA of Csk family tyrosine kinase from human lymphocytes].

Tyrosine kinases of Csk family play important role in the cell growth regulation and normal cell differentiation and also can participate in the process of cancer genesis as oncoproteins. The main function of these tyrosine kinases is the phosphorylation of the Src family tyrosine kinases at their carboxyl terminus, which is the basis of their activity negative regulation. The disturbance of the csk gene expression leads to the increase of the Src tyrosine kinase activity. We have cloned a full-length encoding cDNA of the tyrosine kinase csk gene of human lymphocytes. 1.6-kilobase cDNA encodes the protein, which consists of 12 exons with conserved SH2 and SH3 domains. The homology between this protein and human Csk tyrosine kinase is 99%. A full-length DNA-copy of human lymphocytes RNA can be used for the analysis of csk gene structure in normal and pathologically changed human cells.

[Phytochrome regulation of the plant phospholipase activity]. / Fitokhromnaia reguliatsiia aktivnosti rastitel'nykh fosfolipaz.

The interaction of external stimuli with receptors of plant cell surface can activate the enzymes of lipid metabolism such as phospholipases C and D. The products of the catalysis, i.e., posphoinositide metabolites, phosphatidic acid, fatty acids, etc. participate in signal transduction as secondary messengers related to numerous regulatory processes. One of the physiologically important factors of regulatory control in plants is light, which plays the crucial role in triggering the cellular signaling network. This review presents the information on phospholipid signaling in plants, which is connected with light transduction processes occurring with the involvement of the plant regulatory pigment phytochrome.

[A role of protein kinase C in signal reactions in outer segments of the bovine retinal rods]. / Rol' proteinkinasy C v signal'nykh reaktsiiakh v naruzhnykh segmentakh palochek setchatki byka.

The effect of modulators of protein kinase C activity on Ca2+ translocation in dark-adapted and bleached retinal rod outer segments (ROS) was studied. The activators (1,2-diacyl glycerol and phorbol-12-myristate-13-acetate) and the inhibitor (chelerythrine chloride) of protein kinase C were shown to stimulate and inhibit the ATP-dependent Ca(2+)-uptake in dark-adapted retinal ROS, correspondingly. Apparently, this action is due to the influence of protein kinase C on Ca(2+)-ATPase activity in these vesicular structures. No involvement of modulators of protein kinase C activity on ATP-dependent Ca(2+)-uptake in bleached retinal ROS was found. The influence of protein kinase C on Ca(2+)-release from retinal ROS was observed. It was shown that the activators and inhibitors of protein kinase C increased the efficiency of this process both in dark-adapted and bleached retinal ROS. The mechanisms of action of the protein kinase C activity modulators on the Ca(2+)-uptake and Ca(2+)-release in retinal ROS are discussed.

[A model of the dynamics of intracellular calcium based on refined kinetics of inhibiting the inositol-1,4,5-trisphoshate-sensitive calcium channel]. / Model' dinamiki vnutrikletochnogo kal'tsiia, osnovannaia na utochnennoi kinetike ingibirovaniia inozitol-1,4,5-trifosfat-chuvstvitel'nogo kal'tsievogo kanala.

Several new models of intracellular calcium dynamics based on refined inositol-1,4,5-triphosphate-sensitive calcium channel kinetics were studied. The refined kinetic schemes take into account that a cytosolic calcium cannot inhibit inositol-1,4,5-triphosphate receptors when they are bound to inositol-1,4,5-triphosphate. The mathematical analysis of intracellular calcium dynamics based on one of these schemes allowed us to show how different types of Ca response to extracellular stimuli, such as excitability, oscillations, sustained elevation of Ca and frequency encoding can arise with a reasonably good fit to experimental data.

[The role of intracellular Ca(2+) pools in the regulation of protoplast volume. Effect of red light on the Ca(2+) mobilization in cytoplasm of Arabidopsis cells]. / Rol' vnutrikletochnykh pulov Ca(2+) v reguliatsii ob''ema protoplastov. Vliianie krasnogo sveta na mobilizatsiiu Ca(2+) v tsitoplazme kletok Arabidopsis.

The changes in cytosol Ca2+ concentration associated with the shrinkage of Arabidopsis cells induced by the inhibitor of Ca(2+)-ATPase, cyclopiazonic acid and the Ca2+ ionophore ionomycin were monitored using the fluorescence of Ca(2+)-sensitive probe chlortetracycline hydrochloride. It was found that these compounds elicited a substantial decrease in fluorescence intensity closely associated with Ca(2+)-release from the intracellular stores to the cytoplasm. The release of Ca2+ from the intracellular depots was accompanied by decrease of plant cell volume. Thapsigargin and 2,5'-ditert-butyl-1,4-benzohydroquinone (highly specific inhibitors of Ca(2+)-ATPase of endoplasmic reticulum) resulted in much weaker changes than cyclopiazonic acid did. It was also found with the help of the same technique that red light (lambda = 660 nm) illumination induced a similar Ca2+ release from the intracellular stores. Moreover, the amplitudes of light-induced fluorescence responses registered in mutant plants differing in the content of phytochrome A (phyAOX) and phytochrome B (phyBOX) were much higher than those registered in wild-type of Arabidopsis.

[Isolation and identification of tyrosine kinase from the cytosolic fraction of bovine retinal rod outer segments]. / Vydelenie i identifikatsiia tirozinkinazy iz tsitozol'noi fraktsii naruzhnykh segmentov palocheksetchatki byka.

It was shown that the cytosol fraction of bovine retinal rod outer segments contains three forms of tyrosine kinase. One of them was purified 171-fold to attain a specific activity of 1.6 nmol/min per mg protein. The isolated protein had a molecular weight of about 54,000 in SDS electrophoresis. It was shown that this protein is a tyrosine-specific protein kinase, capable of autophosphorylation at the tyrosine residues and restoration of kinase activity upon denaturation-renaturation.

[Light inhibits tyrosine kinase in rod outer segments in vitro]. / Svet ingibiruet tirozinkinaznuiu aktivnost' v naruzhnykh segmentakh palochek setchatki in vitro.

It was shown that short-term (10 min) light exposure of dark-adapted retinal rod outer segments (ROS) leads to a threefold inhibition of the tyrosine kinase activity. Tyrosine kinase activity in the ROS from bleached retinas is by 30% lower than in the dark-adapted ROS. Prolonged illumination (60 min) of the dark-adapted ROS restores the tyrosine kinase activity to the level of ROS from the bleached retinas.

[Role of secondary phosphoinositide messengers in storage of Ca2+ ions in retinal rod microsomes]. / Rol' vtorichnykh mediatorov fosfoinozitidnoi prirody v deponirovanii ionov Ca2+ mikrosomami palochki setchatki.

The influence of guanosine-5'-triphosphate and secondary messengers forming in rod outer segment membranes during light-stimulated hydrolysis of phosphoinositides on the ATP-dependent Ca(2+)-uptake in microsomes of the retinal rod inner segment was studied. The water-soluble cytoplasmic components of the retinal rod outer segment were shown to be capable of stimulating the Ca(2+)-pump of endoplasmic reticulum after light illumination. This process is likely to proceed with the participation of 1,2-diacylglycerol localized in microsome membrane.

[The calcium-mobilizing effect of inositol-1,4,5-triphosphate in rod outer segments and disks]. / O Ca2+ mobilizuiushchem deistvii inozit-1,4,5-trifosfata v naruzhnykh segmentakh palochki i diskakh.

The effect of inositol-1,4,5-trisphosphate (IP3) on the release of calcium ions from retinal rod discs was studied. It was shown that the release of Ca2+ from discs is an electroneutral process. The intradiscal calcium concentration during the release of the ion from the organelle decreases by 1 mM. It was found that the IP3-dependent release of Ca2+ ions from discs is activated by guanosine triphosphate and beta gamma-transducin. The increase in calcium concentration in the medium also activates the IP3-dependent release of Ca2+ ions from discs, which probably is due to the stimulation of phospholipase C. It is suggested that the functional role of the release of ions in related not to phototransduction but to slow regulatory and adaptation processes in the photoreceptor cell.

[Inorganic phosphate is used for synthesis of phosphatidylinositol-4,5-diphosphate]. / Neorganicheskii fosfat ispol'zuetsia dlia sinteza fosfatidilinozitol- 4,5-difosfata.

It was shown that exogenous inorganic phosphate can be incorporated into newly synthesized phosphatidylinositol-4,5-bisphosphate without any participation of ATP.

[Phosphorylation of proteins and phosphoinositides in the axoneme of the bovine rod outer segments. The effect of structural factor]. / Fosforilirovanie belkov i fosfoinozitidov v aksoneme naruzhnogo segmenta palochki setchatki byka. Vliianie strukturnogo faktora.

The protein composition of microtubular structures of bovine retinal rod axoneme and phosphorylation of its proteins were studied. The axoneme was shown to consist of proteins of 25, 43, 51, 112, 145 and 240 kDa molecular mass. It was demonstrated that 32P is mainly incorporated into the 25, 43 and 51 kDa proteins. cGMP was found to enhance 32P. Incorporation into these proteins. In the presence of Ca(2+)-calmodulin the phosphorylation of the 43 and 51 kDa proteins was increased. The phosphoinositides were shown to be phosphorylated in axoneme. Phosphatidylinositol 4-monophosphate was found to be a principal substrate for phosphatidylinositol kinases to form phosphatidylinositol 4,5-bisphosphate. Ca2+, neomycin and colchicine inhibited 32P incorporation into phosphatidylinositol 4,5-bisphosphate indicating the dependence of phosphatidylinositol 4-monophosphate phosphorylation on structural state of axoneme. Phosphatidylinositol was found to diminish the axoneme ability for the polymerization of microtubules. Data was showed that kinases responsible for protein and phosphoinositides phosphorylation were tightly bound to axoneme structures.