A case of experimental transmission of the causative agent of plague from Ornithodoros tartakovskyi ticks to fleas of the great gerbil

Biological interrelations between ectoparasites from the colonies of great gerbil were studied experimentally. Hungry fleas Coptopsylla lamellifer are able to feed on the ticks Ornithodoros tartakovskyi infected with plague and in so doing be infected with plague agent. Such feeding is identified as "heterovampirism".     

An Exposure to the Oxidized DNA Enhances Both Instability of Genome and Survival in Cancer Cells

Background

Cell free DNA (cfDNA) circulates throughout the bloodstream of both healthy people and patients with various diseases and acts upon the cells. Response to cfDNA depends on concentrations and levels of the damage within cfDNA. Oxidized extracellular DNA acts as a stress signal and elicits an adaptive response.

Principal Findings

Here we show that oxidized extracellular DNA stimulates the survival of MCF-7 tumor cells. Importantly, in cells exposed to oxidized DNA, the suppression of cell death is accompanied by an increase in the markers of genome instability. Short-term exposure to oxidized DNA results in both single- and double strand DNA breaks. Longer treatments evoke a compensatory response that leads to a decrease in the levels of chromatin fragmentations across cell populations. Exposure to oxidized DNA leads to a decrease in the activity of NRF2 and an increase in the activity of NF-kB and STAT3. A model that describes the role of oxidized DNA released from apoptotic cells in tumor biology is proposed.

Conclusions/Significance

Survival of cells with an unstable genome may substantially augment progression of malignancy. Further studies of the effects of extracellular DNA on malignant and normal cells are warranted.     

The Burden of Drug-Resistant Tuberculosis in Papua New Guinea: Results of a Large Population-Based Survey

Background

Reliable estimates of the burden of multidrug-resistant tuberculosis (MDR-TB) are crucial for effective control and prevention of tuberculosis (TB). Papua New Guinea (PNG) is a high TB burden country with limited information on the magnitude of the MDR-TB problem.

Methods

A cross-sectional study was conducted in four PNG provinces: Madang, Morobe, National Capital District and Western Province. Patient sputum samples were tested for rifampicin resistance by the Xpert MTB/RIF assay and those showing the presence of resistance underwent phenotypic susceptibility testing to first- and second-line anti-TB drugs including streptomycin, isoniazid, rifampicin, ethambutol, pyrazinamide, ofloxacin, amikacin, kanamycin and capreomycin.

Results

Among 1,182 TB patients enrolled in the study, MDR-TB was detected in 20 new (2.7%; 95% confidence intervals [CI] 1.1–4.3%) and 24 previously treated (19.1%; 95%CI: 8.5–29.8%) TB cases. No case of extensively drug-resistant TB (XDR-TB) was detected. Thirty percent (6/20) of new and 33.3% (8/24) of previously treated cases with MDR-TB were detected in a single cluster in Western Province.

Conclusion

In PNG the proportion of MDR-TB in new cases is slightly lower than the regional average of 4.4% (95%CI: 2.6–6.3%). A large proportion of MDR-TB cases were identified from a single hospital in Western Province, suggesting that the prevalence of MDR-TB across the country is heterogeneous. Future surveys should further explore this finding. The survey also helped strengthening the use of smear microscopy and Xpert MTB/RIF testing as diagnostic tools for TB in the country.     

A family of highly diverse human and mouse genes structurally links leukocyte FcR,gp42 and PECAM-1

A group of genes encoding proteins structurally related to the leukocyte Fc receptors (FcRs) and termed the IFGP family was identified in human and mouse. Sequences of four human and two mouse cDNAs predict proteins differing by domain composition. One of the mouse cDNAs encodes a secreted protein, which, in addition to four immunoglobulin (Ig)-like domains, contains a scavenger receptor superfamily-related domain at the C-terminus. The other cDNAs code for the type I transmembrane proteins with the extracellular parts comprised of one to six Ig-like domains. Five homologous types of the Ig-like domains were defined and each protein was found to have a unique combination of the domain types. The cytoplasmic tails of the transmembrane proteins show different patterns of the tyrosine-based signal motifs. While the human IFGP members appear to be B-cell antigens, the mouse genes have a broader tissue distribution with predominant expression in brain. Sequence comparisons revealed that the IFGP family may be regarded as a phylogenetic link joining the leukocyte FcRs with the rat NK cell-specific gp42 antigen and platelet endothelial cell adhesion molecule-1 (PECAM-1), two mammalian leukocyte receptors whose close relatives were not found previously. It is suggested that FcRs, the IFGP proteins and gp42 have arisen by a series of duplications from a common ancestor receptor comprised of five Ig-like domains. The organization of the human genes shows that the IFGP family evolved through differential gain and loss of exons due to recombination and/or mutation accumulation in the duplicated copies.     

The postradiation use of vitamin-containing complexes and a phycocyanin extract in a radiation lesion in rats

Wistar rats have been exposed to X-rays with a dose of 5 Gy. Significant decrease in dehydrogenase activity, energy-rich phosphate level and efficiency of antioxidant defence and significant increase in pyruvate amount were observed within 4 weeks. It was also found that the feeding of exposed rats with phycocyanin extract from blue-green algae Spirulina platensis lead to correcting effect. The same result was observed after injections of tocopherol or complex of six water-soluble vitamins. The combination of above mentioned compounds had more marked effect, especially at the presence unitiole and Na2Se.     

Solitary restriction endonucleases in prokaryotic genomes

Prokaryotic restriction-modification (R-M) systems defend the host cell from the invasion of a foreign DNA. They comprise two enzymatic activities: specific DNA cleavage activity and DNA methylation activity preventing cleavage. Typically, these activities are provided by two separate enzymes: a DNA methyltransferase (MTase) and a restriction endonuclease (RE). In the absence of a corresponding MTase, an RE of Type II R-M system is highly toxic for the cell. Genes of the R-M system are linked in the genome in the vast majority of annotated cases. There are only a few reported cases in which the genes of MTase and RE from one R-M system are not linked. Nevertheless, a few hundreds solitary RE genes are present in the Restriction Enzyme Database (http://rebase.neb.com) annotations. Using the comparative genomic approach, we analysed 272 solitary RE genes. For 57 solitary RE genes we predicted corresponding MTase genes located distantly in a genome. Of the 272 solitary RE genes, 99 are likely to be fragments of RE genes. Various explanations for the existence of the remaining 116 solitary RE genes are also discussed.     

Identification of catalytically active groups of pea (<Emphasis Type="Italic">Pisum sativum</Emphasis> L.) β-glucosidase

Functional groups of cytoplasmic pea β-glucosidase pretreated to an electrophoretically homogeneous state were identified. Data on the pH dependence of the enzyme activity, calculated heat of ionization, photoinactivation of the enzyme in the presence of methylene blue, and inactivation of the enzyme with diethyl pyrocarbonate suggest that the catalytic site of β-glucosidase contains the carboxyl group of glutamic or aspartic acids and the imidazole group of histidine.     

The compositional characteristics of the cellular fatty acids in strains of Klebsiella pneumoniae serovar K 1

Klebsiella pneumoniae, serovar K1 strains, differ essentially in the composition of cellular fatty acids from serovar strains K 2, K 3, K 7-K 72, K 74-K 80 of this species and are analogous to K. rhinoscleromatis and K. ozaenae by the given trait. The differences concern the concentration of cyclopropane fatty acids and their biosynthetic precursors--monounsaturated fatty acids, that is typical of a number of other bacteria belonging to the related species and, evidently, may be a marker of phenetic differences at the level of related taxonomic groups. The data obtained evidence for taxonomic separation of K. pneumoniae serovar K1 strains from representatives of other serovars of the given species.