Свойства асфальтобетонов холодного типа на основе жидких вяжущих различного состава

Исследованы физико-механические свойства жидких битумополимерных вяжущих и холодных асфальтобетонов на их основе. Введение в состав жидких битумов ПАВ катионного типа и добавки полимера приводит к снижению слеживае- мости смесей и повышению длительной водоустойчивости асфальтобетонов. Характерной особенностью холодных асфальтобетонов на основе жидкого битума и битумополимерного вяжущего, содержащих катионное ПАВ, является более высокие значения коэффициентов длительной водоустойчивости до и после прогрева, по сравнению с бетонами на битумах без поверхностно-активного вещества. (The physical and mechanical properties of liquid bituminopolymer binders and cold asphalt concrete on their basis are studied. The introduction of cationic surfactants into the composition of liquid bitumens and the addition of polymer leads to a decrease in the caking of the mixtures and an increase in the long-term water resistance of asphalt concrete. A characteristic feature of cold asphalt concretes based on liquid bitumen and bituminopolymer binder containing cationic surfactant is higher values of long-term water resistance coeffi cients before and after heating, as compared to concrete on bitumens without a surfactant.

Genetic and biochemical analyses of chromosome and plasmid gene homologues encoding ICL and ArCP domains in Vibrioanguillarum strain 775

Anguibactin, the siderophore produced by Vibrio anguillarum 775 is synthesized from 2,3-dihydroxybenzoic acid (DHBA), cysteine and hydroxyhistamine via a nonribosomal peptide synthetase (NRPS) mechanism. Most of the genes encoding anguibactin biosynthetic proteins are harbored by the pJM1 plasmid. In this work we report the identification of a homologue of the plasmid-encoded angB on the chromosome of strain 775. The product of both genes harbor an isochorismate lyase (ICL) domain that converts isochorismic acid to 2,3-dihydro-2,3-dihydroxybenzoic acid, one of the steps of DHBA synthesis. We show in this work that both ICL domains are functional in the production of DHBA in V. anguillarum as well as in E. coli. Substitution by alanine of the aspartic acid residue in the active site of both ICL domains completely abolishes their isochorismate lyase activity in vivo. The two proteins also carry an aryl carrier protein (ArCP) domain. In contrast with the ICL domains only the plasmid encoded ArCP can participate in anguibactin production as determined by complementation analyses and site-directed mutagenesis in the active site of the plasmid encoded protein, S248A. The site-directed mutants, D37A in the ICL domain and S248A in the ArCP domain of the plasmid encoded AngB were also tested in vitro and clearly show the importance of each residue for the domain function and that each domain operates independently.

Immunohistochemical Profile of Mucins and their Expression in Precancerous Changes of the Stomach

The aim of this study was to assess the profile of mucins (MUC1, MUC2, MUC5AC) in the intestinal metaplasia (IM) of the gastric mucosa through the immunohistochemical method. Methods: To identify the metaplastic areas in the gastric mucosa, chromoendoscopy was employed using 0.5% solution of methylene blue. The expression of the profile of the mucins was determined using immunohistochemistry with MUC1, MUC5AC, and MUC2 antibodies (clone Ma695, clone CLH2, Ccp58 and CLH5, "Novocastra "Great Britain). Results: In the regions adjacent to the adenocarcinoma and neoplastic modified cells, a visible weak expression of MUC2 and MUC5AC was observed. In the case of complete IM, a visibly maximum MUC2 expression was observed in the goblet cells; thus, the MUC5AC, MUC1, and MUC6 marking were absent in the columnar epitheliocytes with the brush border. In the case of incomplete IM, along with the positive MUC2 markings of the goblet cells, the presence of gastric mucin (MUC5AC) has been observed in 25% of such patients with chronic atrophic gastritis (CAG) having incomplete IM; however, in the columnar epitheliocytes the characteristic occurrence of gastric mucin (MUC5AC) was observed in 100% of the patients while a small amount of MUC2 was recorded in 15% of patients. Conclusion: The MUC5AC expression of the gastric mucins in the columnar epithelial cells and the goblet exocrinocytes marks the formation of the gastrointestinal phenotype viz., incomplete intestinal metaplasia, along with the simultaneous production of the MUC2 by the goblet cells. The decrease with further loss of the protective MUC5AC production by the columnar epithelial cells and goblet exocrinocytes that were found in the regions of severe dysplasia and IM, adjacent to the neoplastic altered cells, may serve as additional criteria of early malignancy of the gastric mucosa

Dynamics of the north western coast of the azov sea

UA: Современная динамика склонов и побережья морей как отображение общего мобилизма литосферы, взаимодействия основных оболочек Земли под влиянием космических, планетарных, региональных и локальных факторов является актуальной научной и практической проблемой. В цепочке геолого-геоморфологических процессов склоновые гравитационные процессы являются наиболее активным звеном и непосредственно влияют на жизнедеятельность человека. В свою очередь, хозяйственная деятельность человека вносит существенные изменения в процесс эволюции геологической среды, в том числе в характер протекания склоновых процессов. EN: Development of slope gravity processes on the coast of the Sea of Azov is a serious environmental and geological problem and requires topical engineering and geological research and solutions. Slope gravitational processes adversely affect the state of the soil layer, causing erosion and washing away of soils, contribute to siltation and contamination of water bodies. Movements on the slopes cause destruction of economic objects, residential buildings, loss of agricultural land. To prevent the negative consequences of slope processes, their deep and systematic study is necessary

Live to cheat another day: bacterial dormancy facilitates the social exploitation of beta-lactamases

The breakdown of antibiotics by β-lactamases may be cooperative, since resistant cells can detoxify their environment and facilitate the growth of susceptible neighbours. However, previous studies of this phenomenon have used artificial bacterial vectors or engineered bacteria to increase the secretion of β-lactamases from cells. Here, we investigated whether a broad-spectrum β-lactamase gene carried by a naturally occurring plasmid (pCT) is cooperative under a range of conditions. In ordinary batch culture on solid media, there was little or no evidence that resistant bacteria could protect susceptible cells from ampicillin, although resistant colonies could locally detoxify this growth medium. However, when susceptible cells were inoculated at high densities, late-appearing phenotypically susceptible bacteria grew in the vicinity of resistant colonies. We infer that persisters, cells that have survived antibiotics by undergoing a period of dormancy, founded these satellite colonies. The number of persister colonies was positively correlated with the density of resistant colonies and increased as antibiotic concentrations decreased. We argue that detoxification can be cooperative under a limited range of conditions: if the toxins are bacteriostatic rather than bacteridical; or if susceptible cells invade communities after resistant bacteria; or if dormancy allows susceptible cells to avoid bactericides. Resistance and tolerance were previously thought to be independent solutions for surviving antibiotics. Here, we show that these are interacting strategies: the presence of bacteria adopting one solution can have substantial effects on the fitness of their neighbours

Construction of Escherichia coli K-12 in-frame, single-gene knockout mutants: the Keio collection

We have systematically made a set of precisely defined, single-gene deletions of all nonessential genes in Escherichia coli K-12. Open-reading frame coding regions were replaced with a kanamycin cassette flanked by FLP recognition target sites by using a one-step method for inactivation of chromosomal genes and primers designed to create in-frame deletions upon excision of the resistance cassette. Of 4288 genes targeted, mutants were obtained for 3985. To alleviate problems encountered in high-throughput studies, two independent mutants were saved for every deleted gene. These mutants—the ‘Keio collection'—provide a new resource not only for systematic analyses of unknown gene functions and gene regulatory networks but also for genome-wide testing of mutational effects in a common strain background, E. coli K-12 BW25113. We were unable to disrupt 303 genes, including 37 of unknown function, which are candidates for essential genes. Distribution is being handled via GenoBase (http://ecoli.aist-nara.ac.jp/)

De novo Biosynthesis of Biodiesel by Escherichia coli in Optimized Fed-Batch Cultivation

Biodiesel is a renewable alternative to petroleum diesel fuel that can contribute to carbon dioxide emission reduction and energy supply. Biodiesel is composed of fatty acid alkyl esters, including fatty acid methyl esters (FAMEs) and fatty acid ethyl esters (FAEEs), and is currently produced through the transesterification reaction of methanol (or ethanol) and triacylglycerols (TAGs). TAGs are mainly obtained from oilseed plants and microalgae. A sustainable supply of TAGs is a major bottleneck for current biodiesel production. Here we report the de novo biosynthesis of FAEEs from glucose, which can be derived from lignocellulosic biomass, in genetically engineered Escherichia coli by introduction of the ethanol-producing pathway from Zymomonas mobilis, genetic manipulation to increase the pool of fatty acyl-CoA, and heterologous expression of acyl-coenzyme A: diacylglycerol acyltransferase from Acinetobacter baylyi. An optimized fed-batch microbial fermentation of the modified E. coli strain yielded a titer of 922 mg L−1 FAEEs that consisted primarily of ethyl palmitate, -oleate, -myristate and -palmitoleate

Assessment of heterologous butyrate and butanol pathway activity by measurement of intracellular pathway intermediates in recombinant Escherichia coli

In clostridia, n-butanol production from carbohydrates at yields of up to 76% of the theoretical maximum and at titers of up to 13 g/L has been reported. However, in Escherichia coli, several groups have reported butyric acid or butanol production from recombinant expression of clostridial genes, at much lower titers and yields. To pinpoint deficient steps in the recombinant pathway, we developed an analytical procedure for the determination of intracellular pools of key pathway intermediates and applied the technique to the analysis of three sets of E. coli strains expressing various combinations of butyrate biosynthesis genes. Low expression levels of the hbd-encoded S-3-hydroxybutyryl-CoA dehydrogenase were insufficient to convert acetyl-CoA to 3-hydroxybutyryl-CoA, indicating that hbd was a rate-limiting step in the production of butyryl-CoA. Increasing hbd expression alleviated this bottleneck, but in resulting strains, our pool size measurements and thermodynamic analysis showed that the reaction step catalyzed by the bcd-encoded butyryl-CoA dehydrogenase was rate-limiting. E. coli strains expressing both hbd and ptb-buk produced crotonic acid as a byproduct, but this byproduct was not observed with expression of related genes from non-clostridial organisms. Our thermodynamic interpretation of pool size measurements is applicable to the analysis of other metabolic pathways

Using Fluorescence Recovery After Photobleaching (FRAP) to study dynamics of the Structural Maintenance of Chromosome (SMC) complex in vivo

The SMC complex, MukBEF, is important for chromosome organization and segregation in Escherichia coli. Fluorescently tagged MukBEF forms distinct spots (or 'foci') in the cell, where it is thought to carry out most of its chromosome associated activities. This chapter outlines the technique of Fluorescence Recovery After Photobleaching (FRAP) as a method to study the properties of YFP-tagged MukB in fluorescent foci. This method can provide important insight into the dynamics of MukB on DNA and be used to study its biochemical properties in vivo

Site-Specific Integration of Foreign DNA into Minimal Bacterial and Human Target Sequences Mediated by a Conjugative Relaxase

This is an open-access article distributed under the terms of the Creative Commons Attribution License.[Background]: Bacterial conjugation is a mechanism for horizontal DNA transfer between bacteria which requires cell to cell contact, usually mediated by self-transmissible plasmids. A protein known as relaxase is responsible for the processing of DNA during bacterial conjugation. TrwC, the relaxase of conjugative plasmid R388, is also able to catalyze site-specific integration of the transferred DNA into a copy of its target, the origin of transfer (oriT), present in a recipient plasmid. This reaction confers TrwC a high biotechnological potential as a tool for genomic engineering. [Methodology/Principal Findings]: We have characterized this reaction by conjugal mobilization of a suicide plasmid to a recipient cell with an oriT-containing plasmid, selecting for the cointegrates. Proteins TrwA and IHF enhanced integration frequency. TrwC could also catalyze integration when it is expressed from the recipient cell. Both Y18 and Y26 catalytic tyrosil residues were essential to perform the reaction, while TrwC DNA helicase activity was dispensable. The target DNA could be reduced to 17 bp encompassing TrwC nicking and binding sites. Two human genomic sequences resembling the 17 bp segment were accepted as targets for TrwC-mediated site-specific integration. TrwC could also integrate the incoming DNA molecule into an oriT copy present in the recipient chromosome. [Conclusions/Significance]: The results support a model for TrwC-mediated site-specific integration. This reaction may allow R388 to integrate into the genome of non-permissive hosts upon conjugative transfer. Also, the ability to act on target sequences present in the human genome underscores the biotechnological potential of conjugative relaxase TrwC as a site-specific integrase for genomic modification of human cells.This work was supported by grant BIO2008-00133 from the Spanish Ministry of Science and Innovation to ML. CGP was a recipient of a predoctoral fellowship from the University of Cantabria, Spain.Peer reviewe