Structure of eremosamine--an amino sugar from the antibiotic eremomycin

A new amino sugar named eremosamine was isolated from hydrolysate of eremomycin, an antibiotic belonging to the group of polycyclic glycopeptides. Crystalline derivatives of the amino sugar i. e. methyleremosaminide and methyl-N,O-acetyleremosaminide (alpha- and beta-anomers) were prepared. The data on PMR study and optic properties of the compounds showed that eremosamine had the structure of 2,3,6-tridesoxy-3-amino-3-C-methyl-L-arabinohexose.     

Spatial configuration of the carbohydrate portion of carminomycins II and III

A neutral fragment of the carbohydrate part of the molecule was isolated in the form of a cyclic acetal (3.5-dinitrobenzoate) from carminomycins II and III belonging to anthracyclines. The acetal preserved all the asymmetric centers. Methanolysis of the cyclic acetal resulted in formation of aldol dimethyl acetal and propylene glycol (3,5-dinitrobenzoate) with isolated asymmetric centers. On the basis of the optic and spectral properties of these compounds it was found that carminomycins II and III differed in the configuration of 2 asymmetric carbon atoms, i.e. acetal atom and the atom in propylene glycol. They had configurations of R (--) in carminomycin II and S (+) in carminomycin III. The third asymmetric center of the acetal in both antibiotics was the same, i.e. S(+).     

Revision of the structure of ristomycinic and actinoidinic amino acids

The structures of ristomycin and actinoidine amino acids described earlier were revised. Crystalline derivatives of the amino acids and the products of their oxidation were prepared. The study on the spectral properties of the compounds showed that ristomycin and actinoidine amino acids had the structures of 3-(2'-hydroxy-5'-glycyl-phenoxy)-4-methyl-5-hydroxyphenylglycine and 2-(2'-hydroxy-5'-glycyl-phenyl)-3,5-dioxyphenylglycine respectively. They did not differ from deaminodicarboxylic acids prepared with ristocetin, vancomycin and actionoidine.     

Microorganisms in the Sediments of Lake Baikal,the Deepest and Oldest Lake in the World

Microbiology - The review summarizes the results of recent studies of microbial communities of the Lake Baikal sediments obtained using diverse techniques. In the sediments of the areas of stable...     

Neutrophil adhesive contact dependence on impingement force

Neutrophil capture and recruitment from the circulation requires the formation of specific receptor/ligand bonds under hydrodynamic forces. In the present study we examine bond formation between beta2-integrins on neutrophils and immobilized ICAM-1 while using micropipettes to control the force of contact between the cell and substrate. Magnesium was used to induce the high affinity conformation of the integrins, and bond formation was assessed by measuring the probability of adhesion during repeated contacts. Increasing the impingement force caused an increase in the contact area and led to a proportional increase in adhesion probability (from approximately 20 to 50%) over the range of forces tested (50-350 pN). In addition, different-sized beads were used to change the force per unit area in the contact zone (contact stress). We conclude that for a given contact stress, the rate of bond formation increases linearly with contact area, but that increasing contact stress results in higher intrinsic rates of bond formation.     

Diversity of cultured aerobic organisms in the areas of natural oil seepage on Lake Baikal

The diversity of cultured aerobic organisms collected from water samples and bottom sediment from two areas of natural oil seepage on Lake Baikal has been researched. Representatives of Alpha-, Beta-, and Gammaproteobacteria have been found in samples collected near the Bol’shaya Zelenovskaya River mouth, while near Cape Gorevoi Utes Betaproteobacteria were absent. Most cultures are characterized by a sufficiently high homology level (96–100%) with nucleotide sequences from the international database.     

Composition of Microbial Communities in Sediments from Southern Baikal Containing Fe/Mn Concretions

Massive parallel sequencing of the 16S rRNA gene fragments was used to investigate the composition and diversity of microbial communities in sediments from Southern Baikal to a depth of 9 cm with 1-cm step. In the layers from the sediment surface to the lower border of oxygen penetration (2 cm), organotrophic bacteria with high similarity to the heterotrophic species Luteolibacter luojiensis constituted the largest fraction of the community. In the formation zone of Fe/Mn crusts (3–5 cm), Proteobacteria and Actinobacteria predominated in the community, while the share of Cyanobacteria was considerable. The lower reduced layers showed an increased contribution of the Bacteroidetes, while the shares of the taxa predominant in the higher layers remained significant. Analysis of archaeal 16S rRNA gene amplicons revealed predominance of the soil and aquatic Thaumarchaeota (Marine Group I lineage), which are involved in anaerobic ammonium oxidation, practically in all sediment layers. The buried oxidized layer (6–7 cm), where members of the uncultured Marine Benthic Group D lineage of the order Thermoplasmatales (Euryarchaeota) predominated, was an exception in this regard. Small numbers of archaea of the Baikal-1 lineages (below 1%) were observed in the communities from the 6–7 and 7–8 cm layers, while the archaea involved in anaerobic methane oxidation (including the ANME-2d group) were not detected.     

PEGylated recombinant L-asparaginase from <Emphasis Type="Italic">Erwinia carotovora</Emphasis>: Production,properties, and potential applications

N-hydroxysuccinimide ester of monomethoxy polyethylene glycol hemisuccinate was synthesized. It acylated amino groups in a molecule of recombinant L-asparaginase from Erwinia carotovora. A method of L-asparaginase modification by the obtained activated polyethylene glycol derivative was developed. The best results were produced by modification of the enzyme with a 25-fold excess of reagent relative to the enzyme tetramer. The modified L-asparaginase was isolated from the reaction mixture by gel filtration on Sepharose CL-6B. The purified bioconjugate did not contain PEG unbound to the protein, demonstrated high catalytic activity, and exhibited antiproliferative action on cell cultures.     

Phylogenetic diversity of microbial communities of the Posolsk Bank bottom sediments,Lake Baikal

Massive parallel sequencing (the Roche 454 platform) of the 16S rRNA gene fragments was used to investigate microbial diversity in the sediments of the Posolsk Bank cold methane seep. Bacterial communities from all sediment horizons were found to contain members of the phyla Actinobacteria, Bacteroidetes, Deinococcus-Thermus, Firmicutes, Nitrospirae, Chloroflexi, Proteobacteria, and the candidate phyla Aminicenantes (OP8) and Atribacteria (OP9). Among Bacteria, members of the Chloroflexi and Proteobacteria were the most numerous (42 and 46%, respectively). Among archaea, the Thaumarchaeota predominated in the upper sediment layer (40.1%), while Bathyarchaeota (54.2%) and Euryarchaeota (95%) were predominant at 70 and 140 cm, respectively. Specific migration pathways of fluid flows circulating in the zone of gas hydrate stability (400 m) may be responsible for considerable numbers of the sequences of Chloroflexi, Acidobacteria, and the candidate phyla Aminicenantes and Atribacteria in the upper sediment layers and of the Deinococcus-Thermus phylum in deep bottom sediments.