Alterations of ciliate phosducin phosphorylation in Blepharisma japonicum cells

We have previously reported that motile photophobic response in ciliate Blepharisma japonicum correlates with dephosphorylation of a cytosolic 28 kDa phosphoprotein (PP28) exhibiting properties similar to those of phosducin. Here we demonstrate in in vivo phosphorylation assay that the light-elicited dephosphorylation of the PP28 is significantly modified by cell incubation with substances known to modulate protein phosphatase and kinase activities. Immunoblot analyses showed that incubation of ciliates with okadaic acid and calyculin A, potent inhibitors of type 1 or 2A protein phosphatases, distinctly increased phosphorylation of PP28 in dark-adapted cells and markedly weakened dephosphorylation of the ciliate phosducin following cell illumination. An enhancement of PP28 phosphorylation was also observed in dark-adapted ciliates exposed to 8-Br-cAMP and 8-Br-cGMP, slowly hydrolysable cyclic nucleotide analogs and 3-isobutyryl-1-methylxanthine (IBMX), a non-specific cyclic nucleotide phosphodiesterase (PDEs) inhibitor. Only slight changes in light-evoked dephosphorylation levels of PP28 were observed in cells treated with the cyclic nucleotide analogs and IBMX. Incubation of ciliates with H 89 or KT 5823, highly selective inhibitor of cAMP-dependent protein kinase (PKA) and cGMP-dependent protein kinase (PKG), respectively, decreased PP28 phosphorylation levels in dark-adapted cells, whereas the extent of light-evoked dephosphorylation of the phosphoprotein was only slightly influenced. Cell treatment with higher Ca2+ concentration together with ionophore A23187 in culture medium resulted in marked increase in PP28 phosphorylation levels, while quite an opposite effect was observed in cells exposed to Ca2+ chelators, EGTA or BAPTA/AM as well as calmodulin antagonists, such as trifluoperazine (TFP), W-7 or calmidazolium. Light-dependent dephosphorylation was not considerably affected by these treatments. The experimental findings presented here suggest that an endogenous light-dependent protein kinase-phosphatase system may be engaged in the alteration of phosducin phosphorylation in ciliate B. japonicum thereby to modulate the cell motile photophobic behavior.     

Binuclear rhodium(II) complexes with leucine and proline

The dimeric rhodium(II) complexes [Rh₂(leu)₄(H₂O)₂]- (ClO₄)₄ and [Rh₂(pro)₄(H₂O)₂](ClO₄)₄ have been prepared and characterized by elemental analyses, i.r., u.v.–vis. and ¹H-n.m.r. spectroscopy. The amino acid molecules are coordinated as bridging ligands via their carboxylato groups. Cyclic voltammetry in DMF has shown that the complexes undergo a quasi-reversible reduction to yield dimers containing a Rh ₂ ³⁺ core. Oxidation processes within the 0–1.5V range were not observed.     

Preparation and characterization of electrodeposited Ni-Ru alloys: morphological and catalytic study

Nickel-ruthenium alloys with various compositions have been deposited by electrodeposition for the first time. Cyclic voltammetry and linear stripping voltammetry measurements show that codeposition of nickel with ruthenium is possible below the potential value of nickel reduction. High-quality alloys containing nickel and ruthenium can be plated at cathodic potentials ranging from − 0.5 to − 1.0 V vs SCE. Deposited coatings were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and atomic force microscopy (AFM). The diffractograms obtained show that an increase of nickel concentration in alloy will lead to a change in the phase composition and formation of NiRu (100) and (101) phases which is observed to be 78 mas.% Ni. SEM studies confirm the surface homogeneity and presence of small, regular grains. AFM observation allows the estimation of the real surface area of obtained alloys which increase with more negative electrodeposition potentials. Ni-Ru alloys were found to be highly electroactive in the water splitting process, which can be connected with the presence of the NiRu phase and a well-developed electroactive area.

Electrochemical deposition of Ni-Ru alloys with various composition and their catalytic activity in water splitting process

     

A study of the relative reactivity of maleic anhydride and some maleimides in free radical copolymerization and terpolymerization

Composition data for the free radical copolymerization of maleic anhydride with N-phenylmaleimide in toluene at 60°C have been obtained. Relative reactivity ratios in terminal and penultimate models using nonlinear least-squares optimization routine have been determined. The standard error was found to be somewhat smaller in the penultimate model, but is still larger than the uncertainty estimated for the copolymer composition. Terpolymers of maleic anhydride and styrene with maleimide, N-butylmaleimide, N-phenylmaleimide, and N-carbamylmaleimide were obtained. On the basis of analysis of the product composition at various monomer feeds the relative reactivity of maleic anhydride and maleimides in these reactions is compared and the influence of the structure of thesemonomers on the rate of some chain growth reactions is discussed.     

Addition of elemental selenium to phosphonate carbanions- - a key step in the synthesis of vinylphosphonates. A new synthetic approach to 1,4-dicarbonyl systems.

A convenient synthesis of vinylphosphonates which involves addition of elemental selenium to phosphonate carbanions followed by alkylation and selenoxide elimination is described. A general approach to 1,4-dicarbonyl systems based on diethyl α-methylthiovinylphosphonate is also reported.     

Estimation of the lipophilicity of antiarrhythmic and antihypertensive active 1-substituted pyrrolidin-2-one and pyrrolidine derivatives

The lipophilicity of some antiarrhythmic and antihypertensive active 1-[2-hydroxy- or 1-[2-acetoxy-3-(4-aryl-1-piperazinyl)propyl]pyrrolidin-2-one derivatives (1-12) has been investigated. Their lipophilicity (R(MO) and log k') was determined by reversed-phase thin-layer chromatography and reversed-phase high-performance liquid chromatography with mixtures of acetonitrile and Tris buffer as mobile phases. The partition coefficients of compounds 1-12 (log P(ScilogP)) were also calculated with the ScilogP program. Comparison of R(MO), log k' and calculated log D(7.0 ScilogP) values enabled calculation of clog D(7.0 TLC) and clog D(7.0 HPLC) values. Preliminary quantitative structure-activity relationship studies indicated that for active compounds there is a dependence between affinity for alpha(2)-adrenoceptors and their clog D(7.0 HPLC) values.     

Dynamic Light Scattering and NMR Studies of Napin

We analyze the structure of napin (BngNAP1), a storage protein (m.w. 14.5 kDa) from Brassica napus. On the basis of the results of ¹H NMR spectroscopy and dynamic light scattering (DLS) studies, the overall shape and secondary structure of the molecule are estimated.     

Studies of the reaction mechanism between copper(II) sulphate and excess copper(I) sulphide

The reaction process between CuSO₄ and excess Cu₂S in the temperature range 650–750 K was investigated by methods of thermal analysis and by studying the phase contentss of the products as a function of the fractional conversion. The reaction proceeds in three steps, with Cu₂S and a new phase described by the formula Cu₂SO₂ as intermediates. This new phase is liquid under the conditions of the reaction. The final product of the reaction is a defective crystalline Cu₂O.

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Zusammenfassung Der Verlauf der Reaktion zwischen CuSO₄ und überschüssigem Cu₂S im Temperaturbereich von 650–750 K wurde mittels thermoanalytischer Methoden und durch Ermittlung der Phasenzusammensetzung in AbhÄngigkeit von der Konversion untersucht. Die Reaktion verlÄuft in drei Schritten mit Cu₂S und einer neuen Phase der Zusammensetzung Cu₂SO₂ als Zwischenproduke. Die neue Phase ist unter den Reaktionsbedingungen eine Flüssigkeit. Endprodukt der Reaktion ist nicht völlig kristallines Cu₂O.

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CuSO₄ Cu₂S 650–750 K . Cu₂S , Cu₂SO₂ . Cu₂O .

     

Determination of aluminium and chromium in serum by atomic absorption spectrometry

Summary The optimal conditions for the determination of aluminium and chromium in blood serum are proposed. Several sample pretreatment procedures for the purpose are compared. The best results are obtained by sample dilution with nitric acid (0.1 mol/l) and addition of Mg(NO₃)₂ as modifier with a magnesium concentration of 0.2 mg/ml. This procedure has been used for studying the intestinal intake of aluminium by patients after oral administration of aluminium compounds.     

Lead tetraacetate-iodine oxidation of 23-spirostanols

Reactions of 23R- and 23S-23-spirostanols in the 25R and 25S series with lead tetraacetate-iodine were studied. The reactions carried out at low temperature afforded d-seco-iododialdehydes and C₂₂ lactones, while similar reactions performed in refluxing tetrachloromethane yielded 20-chlorolactones and their 21-acetoxy derivatives irrespective of the hydroxyl group configuration at C-23. The reaction mechanisms are discussed.