Role of efflux pumps in adaptation and resistance of Listeria monocytogenes to benzalkonium chloride

In this study, potential mechanisms underlying resistance and adaptation to benzalkonium chloride (BC) in Listeria monocytogenes were investigated. Two groups of strains were studied. The first group consisted of strains naturally sensitive to BC which could be adapted to BC. The second group consisted of naturally resistant strains. For all adapted isolates, there was a correlation between the resistance to BC and ethidium bromide, but this was not the case for the naturally resistant isolates. To investigate the role of efflux pumps in adaptation or resistance, reserpine, an efflux pump inhibitor, was added to the strains. Addition of reserpine to the sensitive and adapted strains resulted in a decrease in the MIC for BC, whereas no such decrease was observed for the resistant strains, indicating that efflux pumps played no role in the innate resistance of certain strains of L. monocytogenes to this compound. Two efflux pumps (MdrL and Lde) have been described in L. monocytogenes. Studies showed low and intermediate levels of expression of the genes encoding the efflux pumps for two selected resistant strains, H7764 and H7962, respectively. Adaptation to BC of sensitive isolates of L. monocytogenes resulted in significant increases in expression of mdrl (P < 0.05), but no such increase was observed for lde for two adapted strains of L. monocytogenes, LJH 381 (P = 0.91) and C719 (P = 0.11). This indicates that the efflux pump Mdrl is at least partly responsible for the adaptation to BC.     

Construction and characterization of combinatorial naive phage library of human scFvs

A combinatorial phage display library of human single-chain antibody fragments (scFv) was constructed on the basis of variable domains of heavy (Vh) and light (VI) genes cloned from the lymphocytes of six healthy donors. The size of the library was 2? 10(8) independent clones. Single-chain antibodies against recombinant human TNF?, vaccinia virus and virus-like particles formed by core protein of hepatitis B virus were selected from the library. Unique scFv sequences were identified using the HaeIII fingerprinting. The specificity of the selected clones was proved by the Western-blot analysis.     

Karyotyping results of the material of spontaneous abortions and miscarriages after using assisted reproductive technologies

The results of a molecular cytogenetic study of the material of spontaneous abortions and nonprogressive pregnancies in the first trimester in 43 couples who were treated with various ART methods are presented in this paper. Chromosomal pathologies (CPs) were present in 28 (65%) samples of chorionic villi. A comparative analysis of the frequency and types of CPs in groups composed according to the pathological states in the semen of males was performed. Recommendations to improve the efficiency of ART are developed based on the data.     

System Integration - A Major Step toward Lab on a Chip

Microfluidics holds great promise to revolutionize various areas of biological engineering, such as single cell analysis, environmental monitoring, regenerative medicine, and point-of-care diagnostics. Despite the fact that intensive efforts have been devoted into the field in the past decades, microfluidics has not yet been adopted widely. It is increasingly realized that an effective system integration strategy that is low cost and broadly applicable to various biological engineering situations is required to fully realize the potential of microfluidics. In this article, we review several promising system integration approaches for microfluidics and discuss their advantages, limitations, and applications. Future advancements of these microfluidic strategies will lead toward translational lab-on-a-chip systems for a wide spectrum of biological engineering applications.     

Distribution of Y chromosomes among native North Americans: a study of Athapaskan population history

In this study, 231 Y chromosomes from 12 populations were typed for four diagnostic single nucleotide polymorphisms (SNPs) to determine haplogroup membership and 43 Y chromosomes from three of these populations were typed for eight short tandem repeats (STRs) to determine haplotypes. These data were combined with previously published data, amounting to 724 Y chromosomes from 26 populations in North America, and analyzed to investigate the geographic distribution of Y chromosomes among native North Americans and to test the Southern Athapaskan migration hypothesis. The results suggest that European admixture has significantly altered the distribution of Y chromosomes in North America and because of this caution should be taken when inferring prehistoric population events in North America using Y chromosome data alone. However, consistent with studies of other genetic systems, we are still able to identify close relationships among Y chromosomes in Athapaskans from the Subarctic and the Southwest, suggesting that a small number of proto-Apachean migrants from the Subarctic founded the Southwest Athapaskan populations.     

Sensor system based on molecular-imprinted polymer membranes for the selective recognition of aflatoxin B1

lymer membranes, synthesized using acrylamide as a functional monomer, were characterized by sufficient mechanical stability and high adsorbtion capability towards aflatoxin B1. The molecularly-imprinted polymer membranes were characterized by the pronounced imprinting effect as well as by insignificant adsorbtion of aflatoxins B2 and G2. Therefore, the synthetic analogues of bioreceptors able to individual recognition of aflatoxin B1 were obtained and used as a basis for the optical sensor system for aflatoxin B1 detection in a concentration range 1-500 ng/ml.     

Comparison of ATP and in vivo bioluminescence for assessing the efficiency of immunomagnetic sorbents for live Escherichia coli O157:H7 cells

AIMS: To develop methods to assess the efficiency of immunomagnetic separation (IMS). METHODS AND RESULTS: The capturing efficiency of biosorbents for Escherichia coli O157:H7, constructed using streptavidin-coated magnetic beads and biotinylated antibodies, was tested using both in vivo and ATP bioluminescence. Both methods were suitable for the enumeration of bacteria captured by the biosorbents. The level of both ATP and in vivo bioluminescence depended on the media used, but was unaffected by the magnetic beads. The capture efficiency depended on time and sample volume, but did not depend on the length of spacer arm of the biotinylation agent. For cell concentrations of 相似文献   

Bluetongue Virus Detection Using Microspheres Conjugated with Monoclonal Antibodies against Group-Specific Protein Vp7 by Flow Virometry

Russian Journal of Bioorganic Chemistry - Bluetongue is a reemerging transmissive infectious disease that threatens all countries with intensive livestock production. In cattle, bluetongue may...     

Aflatoxin-selective molecularly-imprinted polymer membranes based on acrylate-polyurethane semi-interpenetrating polymer networks

Synthetic analogs of biological receptors able to group-selective recognition of aflatoxins were obtained using the combination of the technique of molecular imprinting with the method of computer modeling. The synthetic receptors were obtained in a form of thin and porous membranes based on semi-interpenetrating polymer networks. The selection of functional monomers able to noncovalent interactions with aflatoxins B1, B2, and G2 was based on the data of computer modeling. Allylamine, diethylaminoethylmethacrylate, and N,N'-methylenebisacrylamide, providing high binding energies with aflatoxins B1, B2, and G2 were selected as functional monomers for the formation of aflatoxin B1-imprinted polymer membranes. It was shown that aflatoxin-B1-imprinted polymeric membranes synthesized using N,N'-methylenebisacrylamide as a functional monomer were characterized with good physico-mechanical properties as well as good adsorbtion capability towards aflatoxin B1. Neglidgible levels of aflatoxin B1 adsorbtion on the surface of blank membranes were observed. High adsorbtion capability of the MIP membranes towards mycotoxins affiliated to the group of aflatoxins was demonstrated, while negligible adsorbtion of ochratoxin A was observed. Therefore, synthetic analogs of biological receptors able to group-selective recognition of aflatoxins in the range 1-1000 ppb were developed.