Effect of heavy metals on photosynthetic apparatus and antioxidant status of elodea

Elodea plants (Elodea (Egeria) densa Planch.) were incubated in the presence of individual and mixed 1 μM sulfate salts of Ni, Cd, Cu, Zn, and Mn to study the influence of heavy metals (HM) on shoot growth, structural-and functional parameters of the photosynthetic apparatus, lipid peroxidation, enzymatic activities of the antioxidant defense system (superoxide dismutase and catalase), and the content of non-protein and protein thiols in leaves. The accumulation of HM in leaves decreased in a row: Mn > Cu > Cd > Zn > Ni. The largest reduction in chlorophyll content was caused by Mn and Cu, whereas the strongest reduction in carotenoid content was induced by Cu. The presence of Cu produced the largest decrease in the maximal quantum efficiency of photosystem II (PSII) (F _v/F _m). These changes were paralleled by the shift of the pro-/antioxidant balance towards the dominance of oxidative processes. The presence of Cd elevated the content of chlorophyll and carotenoids without altering the photochemical efficiency of PSII; Cd retarded the shoot growth but had no appreciable effect on leaf mesostructure. The addition of the second metal to the growth medium alleviated in most treatments the detrimental action of individual ions owing to the enhanced activities of SOD and catalase and because of the significant increase in the content of non-protein thiols. It is supposed that the observed antagonism of metal ions is related to their competitive interactions restricting the entry of HM into the cell.     

Cloning, expression and characterization of the recombinant Yersinia pseudotuberculosis L-asparaginase

We have cloned ansB (YPTB1411) gene from Yersinia pseudotuberculosis Q66CJ2 and constructed stable inducible expression system that overproduce L-asparaginase from Y. pseudotuberculosis (YpA) in Escherichiacoli BL21 (DE3) cells. For purification of YpA we used Q-Sepharose and DEAE-Toyopearl column chromatography. We examined kinetics of the enzyme reaction, catalytic activity as a function of pH, temperature and ionic strength, thermostability and other enzyme properties. Biochemical properties of YpA are similar with those of E. coli type II L-asparaginase. K(m) for L-asparagine is 17 ± 0.9 μM and pI 5.4 ± 0.3. Enzyme demonstrates maximum activity at pH 8.0 and 60 °C. YpA L-glutaminase activity is relatively low and more than 15 times less than specific activity towards L-asn. We evaluated also the antiproliferative effect of YpA in vitro and in vivo with E. colil-asparaginase (EcA) as the reference substance at similar conditions.     

Development of a 3D finite element model of lens microcirculation

Background

It has been proposed that in the absence of a blood supply, the ocular lens operates an internal microcirculation system. This system delivers nutrients, removes waste products and maintains ionic homeostasis in the lens. The microcirculation is generated by spatial differences in membrane transport properties; and previously has been modelled by an equivalent electrical circuit and solved analytically. While effective, this approach did not fully account for all the anatomical and functional complexities of the lens. To encapsulate these complexities we have created a 3D finite element computer model of the lens.

Methods

Initially, we created an anatomically-correct representative mesh of the lens. We then implemented the Stokes and advective Nernst-Plank equations, in order to model the water and ion fluxes respectively. Next we complemented the model with experimentally-measured surface ionic concentrations as boundary conditions and solved it.

Results

Our model calculated the standing ionic concentrations and electrical potential gradients in the lens. Furthermore, it generated vector maps of intra- and extracellular space ion and water fluxes that are proposed to circulate throughout the lens. These fields have only been measured on the surface of the lens and our calculations are the first 3D representation of their direction and magnitude in the lens.

Conclusion

Values for steady state standing fields for concentration and electrical potential plus ionic and fluid fluxes calculated by our model exhibited broad agreement with observed experimental values. Our model of lens function represents a platform to integrate new experimental data as they emerge and assist us to understand how the integrated structure and function of the lens contributes to the maintenance of its transparency.     

Influence of ligands’ peripheral substituents on the structure, magnetochemical and electrochemical behaviour of complexes containing a Cu2O2 butterfly core

New polydentate open structure ligands H₃L1 and H₃L2 were synthesized by the condensation of 2,6-diformyl-4-tert-butylphenol and corresponding N-R-o-phenylenediamines (R = Ac and R = Boc). Treating of the ligands with copper trimethylacetate leads to binuclear copper complexes with dissimilar Cu₂O₂ cores, the structures of which were solved by X-ray diffraction analysis. The electrochemical properties of both complexes were studied; the observed redox transitions were assigned to specific redox-active sites of the molecule. These assignments were confirmed by DFT calculations of the electronic structure of binuclear complexes. Both complexes exhibit antiferromagnetic behaviour, as confirmed by variable-temperature magnetic studies.     

Elastase and acid phosphatase activity in bronchoalveolar lavage fluid during chronic bronchitis

The dynamics of acid phosphatase and granulocytic elastase activities in bronchoalveolar washings of 40 patients with chronic catarrhal bronchitis was studied. In case of effective cure, the activities of these enzymes were increased shortly on the 10-13 days from beginning of the cure. In order to study the nature of this enzymes, the additional researches were conducted. These researches demonstrated that the macrophages were the source of the acid phosphatase, and the neutrophils--elastase. The transitory increase of the activity of both enzymes is favourable prognostical sign of disease's course.     

Transport of basic amino acids into Yersinia pestis cells

The transport of the basic amino-acids into the plague microbe cells has been shown to proceed by means of two transfer systems, the common transfer system and the system specific for lysine. Besides that, arginine can be transported into the plague microbe cells by the histidine transport system. The vaccine strain EV NIIEG was used as a model to study the amino-acid transport systems.     

Synthesis,in vitro biological activity,hydrolytic stability and docking of new analogs of BIM-23052 containing halogenated amino acids

One of the potent somatostatin analogs, BIM-23052 (DC-23-99) d-Phe-Phe-Phe-d-Trp-Lys-Thr-Phe-Thr-NH₂, has established in vitro growth hormone inhibitory activity in nM concentrations. It is also characterized by high affinity to some somatostatin receptors which are largely distributed in the cell membranes of many tumor cells. Herein, we report the synthesis of a series of analogs of BIM-23052 containing halogenated Phe residues using standard solid-phase peptide method Fmoc/OtBu-strategy. The cytotoxic effects of the compounds were tested in vitro against two human tumor cell lines—breast cancer cell line and hepatocellular cancer cell line, as well as on human non-tumorigenic epithelial cell line. Analogs containing fluoro-phenylalanines are cytotoxic in μM range, as the analog containing Phe (2-F) showed better selectivity against human hepatocellular cancer cell line. The presented study also reveals that accumulation of halogenated Phe residues does not increase the cytotoxicity according to tested cell lines. The calculated selective index reveals different mechanisms of antitumor activity of the parent compound BIM-23052 and target halogenated analogs for examined breast tumor cell lines. All peptides tested have high antitumor activity against the HepG2 cell line (IC₅₀ ≈ 100 μM and SI > 5) compared to breast cells. This is probably due to the high permeability of the cell membrane and the higher metabolic activity of hepatocytes. In silico docking studies confirmed that all obtained analogs bind well with the somatostatin receptors with preference to ssrt3 and ssrt5. All target compounds showed high hydrolytic stability at acid and neutral pH, which mimic physiological condition in stomach and human plasma.