The study of the reaction of terminated oligomerization in the synthesis of oligo-(β1-6)-glucosamines

The applicability of terminated oligomerization to the synthesis of oligo-(β1-6)-glucosamines, fragments of the intercellular polysaccharide adhesin of staphylococci, was studied. The reactions of terminated oligomerization were carried out with mono-, di-, and trisaccharide monomers and N-protected aminopropanol; and spacered mono-and disaccharides as terminating molecules were also attempted. The primary formation of cyclic products of monomer intramolecular glycosylation was observed in almost all the reactions. Only the experiments with the monomer based on the disaccharide bromide under the conditions of the Helferich reaction led to reduced yields (30%) of the cyclic products. However, even in this case, the desired terminated oligosaccharides were generated in approximately 10% yield and mainly were the products of single glycosylation of the terminator by the monomer. These experiments allow the conclusion that, under the examined conditions, the reaction of terminated oligomerization could not result in the synthesis of oligoglucosamines with a high molecular mass.     

Studies on the effects of low temperatures on lactic acid bacteria

Studies were conducted on different strains of L. bulgaricus, L. casei, S. thermophilus, S. lactis, and S. cremoris isolated in Bulgaria and applied as pure cultures and in combinations as starters. All the strains under investigation were found to preserve, on “freezing-thawing” their characteristic morphological and biochemical properties, regardless of the temperature and rate of cooling, but the optimum freezing temperature of the strains studied is ?196 °C (in liquid nitrogen). High cooling rates provide higher viability and activity of lactic acid bacterial cells. Lactic acid streptococci, S. lactis and S. thermophilus, are considerably more resistant than lactic acid rods, L. casei and L. bulgaricus, at all the freezing regimens tested.     

Stathmin Potentiates Vinflunine and Inhibits Paclitaxel Activity

Cell biology and crystallographic studies have suggested a functional link between stathmin and microtubule targeting agents (MTAs). In a previous study we showed that stathmin increases vinblastine (VLB) binding to tubulin, and that conversely VLB increases stathmin binding to tubulin. This constituted the first biochemical evidence of the direct relationship between stathmin and an antimitotic drug, and revealed a new mechanism of action for VLB. The question remained if the observed interaction was specific for this drug or represented a general phenomenon for all MTAs. In the present study we investigated the binding of recombinant stathmin to purified tubulin in the presence of paclitaxel or another Vinca alkaloid, vinflunine, using Isothermal Titration Calorimetry (ITC). These experiments revealed that stathmin binding to tubulin is increased in the presence of vinflunine, whereas no signal is observed in the presence of paclitaxel. Further investigation using turbidity and co-sedimentation showed that stathmin inhibited paclitaxel microtubule-stabilizing activity. Taken together with the previous study using vinblastine, our results suggest that stathmin can be seen as a modulator of MTA activity and binding to tubulin, providing molecular explanation for multiple previous cellular and in vivo studies showing that stathmin expression level affects MTAs efficiency.     

Conjugates of cyclooligosaccharide scaffolds and carbohydrate ligands: Methods for synthesis and the interaction with lectins

The main approaches to the preparation of mono- and oligodentate glycoconjugates based on cyclodextrin and cyclooligo-β-(1 → 6)-D-glucosamine scaffolds are surveyed in the review. The data on the biological activity of the glycoconjugates are discussed exemplified in their interaction with carbohydrate-binding proteins named lectins.     

Molecular genetic identification of the phytopathogenic fungus <Emphasis Type="Italic">Cryphonectria parasitica</Emphasis>

Mycological analysis of samples of sweet chestnut (Castanea sativa) collected in the northern Turkish zone of its habitat was carried out. A total of 300 strains of micromycetes belonging to 13 taxa were isolated in pure cultures. The phytopathogenic fungus Cryphonectria parasitica, the causal agent of chestnut blight, was identified among these strains. A technique for detection of C. parasitica in pure culture and host tissues using species-specific PCR markers was developed and tested. This technique can be used as an express method for detection of chestnut blight.     

Transgenic tobacco plants accumulating osmolytes show reduced oxidative damage under freezing stress.

We studied the reaction to the oxidative component of freezing in several tobacco lines, transformed with genes coding for enzymes involved in the synthesis of osmoprotectants (proline, fructan or glycine betaine) along with their wild type. The levels of some oxidative stress markers (leakage of electrolytes, hydrogen peroxide and malondialdehyde) as well as the activity of antioxidative enzymes catalase (EC 1.11.1.6.) and guaiacol peroxidase (EC 1.11.1.7.) have been followed at acclimation, 12 and 24 h freezing and at recovery. Freezing for 24 h resulted in severe damages for the wild type. A corresponding increase of electrolyte leakage, hydrogen peroxide and malondialdehyde contents, a rise of peroxidase activity and inhibition of catalase activity occurred in the non-transformants. Similar, but significantly lower trend of the same parameters has been found for the transgenic lines. Moreover, the oxidative markers returned to their normal levels when the transformants were able to recover from freezing. It could be speculated that transfer of genes, coding for accumulation of osmoprotectants, is related to reduced intensity of freezing-induced oxidative processes. Our lines and model system could serve as a good prerequisite for additional studies to gain further insights into the complex role of osmoprotectants in freezing tolerance.     

Genetic Variation of Wild Soybean Glycine soja Sieb. et Zucc. in the Far East Region of the Russian Federation

Polymorphism of RAPD markers was analyzed in the wild soybean populations from the Far East region of Russia. The level of RAPD marker polymorphism was significantly higher in the wild than in the cultivated soybean. The results obtained suggest active development of genetically different groups of wild soybean. Geographically isolated subpopulations showed maximum distance from the main population of wild soybean.     

Calcitonin antibodies in experimental diabetes mellitus

Antibodies to calcitonin appear in blood of rats with experimental alloxan diabetes. This phenomenon is observed only under high blood sugar. At the stage of latent diabetes, i.e. during alloxan administration to the body and low blood sugar no antibodies to calcitonin are detected. It is possible that appearance of autoantibodies to calcitonin is one of pathogenetic factors of hyperglycemia development in rats with alloxan diabetes.     

Immune response to a synthetic polysaccharide and protein conjugate

Synthetic polysaccharide (S-PS) containing aglycone-spacer with a free amino group was really alpha 1,6-mannan with Cn approximately 10. S-PS was transformed into isothiocyanate derivative by treating it with thiophosgene and engaged into reaction with amino group of bovine serum albumin (BSA) lysine residues. Rabbits were immunized with S-PS-BSA conjugate and antibodies to S-PS titres were estimated by means of ELISA. S-PS-BSA conjugate was proved to provoke specific anti-polysaccharide antibodies formation in rabbits.