Search

Tuberculosis caused by multidrug-resistant (MDR) and extensively drug-resistant (XDR) Mycobacterium tuberculosis (MTB) strains is a growing problem in many countries. The availability of the complete nucleotide sequences of several MTB genomes allows to use the comparative genomics as a tool to study the relationships of strains and differences in their evolutionary history including acquisition of drug-resistance. In our work, we sequenced three genomes of Russian MTB strains of different phenotypes – drug susceptible, MDR and XDR. Of them, MDR and XDR strains were collected in Tomsk (Siberia, Russia) during the local TB outbreak in 1998–1999 and belonged to rare KQ and KY families in accordance with IS6110 typing, which are considered endemic for Russia. Based on phylogenetic analysis, our isolates belonged to different genetic families, Beijing, Ural and LAM, which made the direct comparison of their genomes impossible. For this reason we performed their comparison in the broader context of all M. tuberculosis genomes available in GenBank. The list of unique individual non-synonymous SNPs for each sequenced isolate was formed by comparison with all SNPs detected within the same phylogenetic group. For further functional analysis, all proteins with unique SNPs were ascribed to 20 different functional classes based on Clusters of Orthologous Groups (COG). We have confirmed drug resistant status of our isolates that harbored almost all known drug-resistance associated mutations. Unique SNPs of an XDR isolate CTRI-4XDR, belonging to a Beijing family were compared in more detail with SNPs of additional 14 Russian XDR strains of the same family. Only type specific mutations in genes of repair, replication and recombination system (COG category L) were found common within this group. Probably the other unique SNPs discovered in CTRI-4XDR may have an important role in adaptation of this microorganism to its surrounding and in escape from antituberculosis drugs treatment. [ABSTRACT FROM AUTHOR]

Thirty urogenital Chlamydia trachomatis isolates collected in Moscow in 2005 were typed using newly developed molecular typing approaches: (1) multilocus sequence typing (MLST7) based on sequences of seven housekeeping genes ( ), (2) MLST5 based on the investigation of five target regions of the chlamydial genome and (3) ompA gene sequencing supplemented with three variable number tandem repeat (VNTR) loci of the genome. ompA typing divided all isolates into 11 groups with E serotype dominating, while MLST7, MLST5 and VNTR analysis divided them into eight, 20 and 18 groups, respectively. The discriminatory power of each method calculated using the Hunter–Gaston discriminatory index was found to be 0.83 for the ompA typing scheme, 0.82 for MLST7 and 0.95 for MLST5. A novel sequence type combining 13% of all strains was discovered, as well as new alleles of genes. This is the first study characterizing the genetic diversity of the urogenital C. trachomatis population in Central Russia using MLST. We conclude that the MLST7 scheme is the best possible choice for global epidemiological purposes, whereas MLST5 is more appropriate for tracing local outbreaks. [ABSTRACT FROM AUTHOR]

EPR paramagnetic probe method with 2,2,6,6-tetramethylpiperidin-N-oxyl (TEMPO) as a probe has been applied to study of electron-accepting properties of the surface of (Y, La0.1)CexZr1−xO2−y (x=0.1–0.7), Y0.1Pr0.3Zr0.6O2−y and Y0.1Pr0.15Ce0.15Zr0.7O2−y mixed oxides. Two types of acceptor sites—coordinatively unsaturated (cus) cations Zr4+ and Ce4+—have been revealed on the CeO2–ZrO2 surface after thermovacuum treatment (820 K). The relative amounts and “strength” of these centers were evaluated on the basis of EPR spectra analysis. An introduction of trivalent Y3+ or La3+ cations reduces the amount of electron-acceptor sites belonging to cerium cations, stabilizing ones as Ce3+. A formation of very strong electron-accepting sites (Pr4+ cus cations) able to form charge transfer complexes with adsorbed TEMPO on the surface of praseodymia-containing samples after thermovacuum treatment was found out. At the same time electron-accepting ability of Zr4+ cationic sites on Y0.1Pr0.3Zr0.6O2−y and Y0.1Pr0.15Ce0.15Zr0.7O2−y surfaces decreases in comparison with ceria–zirconia one. The generally used IR spectroscopy technique with CO as a probe molecule appeared to be considerably less informative for such systems characterization, due to their high catalytic activity to carbon monoxide. A formation of paramagnetic Zr3+ ions in ceria–zirconia mixed oxides has been investigated by EPR spectroscopy technique. The different states of this paramagnetic ion are realized in the complex oxides depending on Ce/Zr ratio. [Copyright &y& Elsevier]