Conformational changes due to vicinal glycosylation: The branched α-l-Rhap(1–2)[β-d-Galp(1–3)]-β-d-Glc1-OMe trisaccharide compared with its parent disaccharides*

Conformations of the α-l -Rhap(1-2)-β-d -Glc1-OMe and β-d -Galp(1-3)-β-d -Glc1-OMe disaccharides and the branched title trisaccharide were examined in DMSO-d₆ solution by ¹H-nmr. The distance mapping procedure was based on rotating frame nuclear Overhauser effect (NOE) constraints involving C- and O-linked protons, and hydrogen-bond constraints manifested by the splitting of the OH nmr signals for partially deuteriated samples. An “isotopomer-selected NOE” method for the unequivocal identification of mutually hydrogen-bonded hydroxyl groups was suggested. The length of hydrogen bonds thus detected is considered the only one motionally nonaveraged nmr-derived constraint. Molecular mechanics and molecular dynamics methods were used to model the conformational properties of the studied oligosaccharides. Complex conformational search, relying on a regular Φ,Ψ-grid based scanning of the conformational space of the selected glycosidic linkage, combined with simultaneous modeling of different allowed orientations of the pendant groups and the third, neighboring sugar residue, has been carried out. Energy minimizations were performed for each member of the Φ,Ψ grid generated set of conformations. Conformational clustering has been done to group the minimized conformations into families with similar values of glycosidic torsion angles. Several stable syn and anti conformations were found for the 1→2 and 1→3 bonds in the studied disaccharides. Vicinal glycosylation affected strongly the occupancy of conformational states in both branches of the title trisaccharide. The preferred conformational family of the trisaccharide (with average Φ,Ψ values of 38°, 17° for the 1→2 and 48°, 1° for the 1→3 bond, respectively) was shown by nmr to be stabilized by intramolecular hydrogen bonding between the nonbonded Rha and Gal residues. © 1998 John Wiley & Sons, Inc. Biopoly 46: 417–432, 1998     

Chemiluminescence of cereal products I. Kinetics,activation energy and effect of solvents

Addition of water to cereal grains and food products such as flour, bread and crackers stimulates ultraweak chemiluminescence, the intensity of which depends upon cereal species, its origin and history, grinding, time after grinding, initial moisture content, solvent, temperature and additives. Pure carbohydrates (e.g. dextran) display much weaker and shorter chemiluminescence. A low activation energy (25 kJ/mol) in the temperature range of 20–40°C, Van't Hoff coefficient of 1.4 and the diminution of chemiluminescence output in ethanol and acetone vs. water suggest that weak molecular interactions, e.g. hydrogen bond scission or formation, determine the rate-limiting steps of chemi-excitation. The emission decay kinetics fit a hyperbolic function rather than an exponential one, thus suggesting a contribution of the recombination-luminescence of ions and free radicals to the mechanism. The results appear to demonstrate a significant role of weak interactions of the water–carbohydrates systems in processes leading to electronic excitation and chemiluminescence. © 1997 John Wiley & Sons, Ltd.     

Determination of the enantiomeric purity of commercial Jacobsen's catalyst samples

A HPLC method is described for the chiral analysis of the commercially available Jacobsen's catalyst. A hydroxypropyl β-cyclodextrin stationary phase was used in conjunction with a nonaqueous, polar-organic mobile phase. The method can be applied to control the enantiomeric purity of the catalyst, which is of great importance for quality control of that product. High accuracy in the determination of trace levels of the unwanted enantiomer in the presence of large amounts of the desired enantiomer is demonstrated. Chirality 10:362–363, 1998. © 1998 Wiley-Liss, Inc.     

Gold nanoparticles and electromagnetic irradiation in tissue culture systems of bleeding heart: biochemical,physiological, and (cyto)genetic effects

Plant Cell, Tissue and Organ Culture (PCTOC) - This study aimed to analyze the effect of various mutagens on the in vitro development, physiological activity, acclimatization efficiency, and...     

Factors influencing taxonomic composition and abundance of macrozoobenthos in extralittoral zone of shallow eutrophic lakes

Zoobenthos is an essential part of shallow lake ecosystems, exerting a considerable impact upon their functioning. We studied 13 eutrophic, shallow, polymictic lakes from Northern Poland to find out which environmental factors influence taxonomic composition, abundance and biodiversity of their zoobenthos. The Canonical Correspondence Analysis allowed to distinguish three lake types: (1) macrophyte-dominated lakes, with high plant cover and well illuminated bottom, inhabited by abundant, diverse benthic taxa; (2) deeper phytoplankton-dominated lakes, with shaded bottom, high sediment oxygen demand (SOD) and rather sparse zobenthos community, dominated by Chironomus and Chaoborus larvae; (3) shallower phytoplankton-dominated lakes, with intermediate amount of light at the bottom and lower SOD values and comparatively diverse zoobenthos, but with lower number of taxa than in the first group. Apart from plant presence, distinguishing between macrophyte-dominated lakes and the other types, the most important variable in the CCA was amount of light reaching the bottom. Probably the impact of light on the bottom fauna was indirect: light stimulated development of macrophytes or phytobenthos (depending on its intensity) and thus improved food and oxygen conditions. Zoobenthos was also affected by oxygen conditions (mainly SOD), presumably by short-time oxygen depletions occurring in the deep phytoplankton-dominated lakes and preventing survival of some benthic taxa.     

Cellobiose dehydrogenase from the ligninolytic basidiomycete Phlebia lindtneri

Cellobiose dehydrogenase (CDH), an extracellular flavocytochrome produced by several wood-degrading fungi, was detected in the culture supernatant of the selective delignifier Phlebia lindtneri maintained on a cellulose-based liquid medium. Cellobiose dehydrogenase was purified to homogeneity by a rapid procedure, using ammonium sulfate precipitation, ion-exchange chromatography, and chromatofocusing. The enzyme was recovered with a 61.2 fold increased specific activity and a yield of 47.5%. As determined by SDS-PAGE, the molecular mass of the purified enzyme was found to be 104.5 kDa and its isoelectric point was 4.0. The carbohydrate content of the purified enzymes was 22%. In this work, the cellobiose dehydrogenase gene cdh1 and its corresponding cDNA from fungi Phlebia lidnteri were isolated, cloned, and characterized. The 2319 bp full-length cDNA of cdh1 encoded a mature CDH protein containing 755 amino acids, which was preceded by a signal peptide of 17 amino acids. The deduced protein sequence of cdh1 shared significant similarity with other known fungal cellobiose dehydrogenase.     

Human–wildlife conflicts at pond fisheries in eastern Poland: perceptions and management of wildlife damage

Wildlife occurring at aquacultural sites can ignite conflicts over resources managed by humans. A telephone survey concerning nuisance wildlife occurrence, perceptions of inflicted damage, and use of preventive measures at pond fisheries was conducted in 2003–2004 in eastern Poland. Significant economic losses to wildlife were reported by 80% of the respondents, with 41% claiming severe losses to more than one species. Serious damage was attributed primarily to otters Lutra lutra (56% of farms), cormorants Phalacrocorax carbo (26%), grey herons Ardea cinerea (23%), and beavers Castor fiber (21%). Two alien species, mink Neovison vison and muskrat Ondatra zibethicus, were widespread, but rarely blamed for causing substantial harm. Lethal controls were the most popular means of damage reduction and were more likely to be deployed at fish farms reporting significant losses. Cormorants, shot at half of the farms visited, were the most widely persecuted. Both otters and beavers were culled, notwithstanding their protection status and compensation payments available for beaver damage to ponds. The survey indicated poor cooperation between conservation authorities and fish farmers in managing wildlife concerns. Monitoring conflict interactions, i.e., wildlife occurrence and alleged damage at fish farms vs damage management processes, is an essential step toward conflict alleviation. Considering the wide range of species interacting with fisheries, adoption of more flexible policies to address the conflicts than a single-species conservation approach is recommended.     

Biologically Active Polymers from Spontaneous Carotenoid Oxidation: A New Frontier in Carotenoid Activity

In animals carotenoids show biological activity unrelated to vitamin A that has been considered to arise directly from the behavior of the parent compound, particularly as an antioxidant. However, the very property that confers antioxidant activity on some carotenoids in plants also confers susceptibility to oxidative transformation. As an alternative, it has been suggested that carotenoid oxidative breakdown or metabolic products could be the actual agents of activity in animals. However, an important and neglected aspect of the behavior of the highly unsaturated carotenoids is their potential to undergo addition of oxygen to form copolymers. Recently we reported that spontaneous oxidation of ß-carotene transforms it into a product dominated by ß-carotene-oxygen copolymers. We now report that the polymeric product is biologically active. Results suggest an overall ability to prime innate immune function to more rapidly respond to subsequent microbial challenges. An underlying structural resemblance to sporopollenin, found in the outer shell of spores and pollen, may allow the polymer to modulate innate immune responses through interactions with the pattern recognition receptor system. Oxygen copolymer formation appears common to all carotenoids, is anticipated to be widespread, and the products may contribute to the health benefits of carotenoid-rich fruits and vegetables.     

Superstatistics analysis of the ion current distribution function: Met3PbCl influence study

A novel analysis of ion current time series is proposed. It is shown that higher (second, third and fourth) statistical moments of the ion current probability distribution function (PDF) can yield new information about ion channel properties. The method is illustrated on a two-state model where the PDF of the compound states are given by normal distributions. The proposed method was applied to the analysis of the SV cation channels of vacuolar membrane of Beta vulgaris and the influence of trimethyllead chloride (Met₃PbCl) on the ion current probability distribution. Ion currents were measured by patch-clamp technique. It was shown that Met₃PbCl influences the variance of the open-state ion current but does not alter the PDF of the closed-state ion current. Incorporation of higher statistical moments into the standard investigation of ion channel properties is proposed.