RESUMO
Blazars are active galactic nuclei (AGN) with relativistic jets whose non-thermal radiation is extremely variable on various timescales1-3. This variability seems mostly random, although some quasi-periodic oscillations (QPOs), implying systematic processes, have been reported in blazars and other AGN. QPOs with timescales of days or hours are especially rare4 in AGN and their nature is highly debated, explained by emitting plasma moving helically inside the jet5, plasma instabilities6,7 or orbital motion in an accretion disc7,8. Here we report results of intense optical and γ-ray flux monitoring of BL Lacertae (BL Lac) during a dramatic outburst in 2020 (ref. 9). BL Lac, the prototype of a subclass of blazars10, is powered by a 1.7 × 108 MSun (ref. 11) black hole in an elliptical galaxy (distance = 313 megaparsecs (ref. 12)). Our observations show QPOs of optical flux and linear polarization, and γ-ray flux, with cycles as short as approximately 13 h during the highest state of the outburst. The QPO properties match the expectations of current-driven kink instabilities6 near a recollimation shock about 5 parsecs (pc) from the black hole in the wake of an apparent superluminal feature moving down the jet. Such a kink is apparent in a microwave Very Long Baseline Array (VLBA) image.
RESUMO
Development of the genotyping methods of glanders agent is urgent due to its high pathogenicity, lack of effective preventive measures and threat of the use of Burkholderia mallei as a biological weapon. In this work we proposed a scheme for the typing of the B. mallei strains based on different region analysis (DFR). The choice of variable loci differentially presented in various strains of glanders agents was performed by analyzing annotated whole-genome sequences of the B. mallei strains. Primers and fluorescence probes were designed for 9 selected loci. The amplification conditions for different regions were optimized in two variants: with electrophoretic detection and hybridization-fluorescence detection in the strip format. The possibility of applying the DFR analysis to genetic characterization of strains was assessed in 14 B. mallei strains. The genetic profiles of the studied B. mallei strains revealed that the developed DFR-typing scheme was characterized by high discrimination power (Hunter-Gaston index value was 0.92), reproducibility, rapidity, easy interpretation, and applicability for epidemiological surveillance of glanders.
Assuntos
Burkholderia mallei/genética , DNA Bacteriano/genética , Técnicas de Genotipagem , Mormo/genética , Reação em Cadeia da Polimerase , Animais , Burkholderia mallei/isolamento & purificação , Humanos , Federação RussaRESUMO
AIM: Determine an optimal set of the most effective methods of identification and intraspecies typing ofcausative agents ofglanders and melioidosis. Materials andmethods. Bacteriologic, immunochemical, molecular-genetic methods were used. RESULTS: A possibility to identify collection strains of pathogenic and closely related Burkholderia in semiautomatic systems is studied. Means of detection of informative variable genome segments ofthe specified microorganisms were developed, methods of their genetic typing were selected. Effectiveness of application of precipitating mAbs for differentiation of Burkholderia was established. Data on diagnostic possibilities of immunoglobulins fluorescing based on monoclonal antibodies of various etiotropic directionality for detection and identification of B. mallei and B. pseudomallei are generalized. Experimental series of amplification test-systems for identification of glanders and melioidosis causative agents in real-time PCR format are created. CONCLUSION: A number of methods for identification and typing of glanders and melioidosis causative agents is proposed.
Assuntos
Burkholderia mallei/genética , Burkholderia pseudomallei/genética , Mormo , Melioidose , Reação em Cadeia da Polimerase em Tempo Real , Animais , Mormo/diagnóstico , Mormo/genética , Humanos , Melioidose/diagnóstico , Melioidose/genéticaRESUMO
The reference-center of monitoring of agents of glanders and melioidosis carried out testing of reagents kits for diagnostic of agent of melioidosis and other close-related species of Burkholderiae in vitro. At the stage of specific identification of pathogenic Burkholderiae the diagnostic possibilities of commercial and experimental kits of reagents for express- and rapid analysis were evaluated. The criteria of evaluation of diagnostic value of kits of reagents were sensitivity, specificity and time of implementation of studies. The analysis with application of mono- and multi-locus amplification systems, including real-time polymerase chain reaction permitted during 5-6 hours to implement identification and differentiation of Burkholderia pseufomallei, B. thailandensis and B. cepacia.
Assuntos
Burkholderia/isolamento & purificação , Mormo/microbiologia , Melioidose/microbiologia , Reação em Cadeia da Polimerase/métodos , Animais , Técnicas de Tipagem Bacteriana/métodos , Burkholderia/classificação , Burkholderia/genética , Burkholderia/patogenicidade , Mormo/genética , Cavalos/genética , Cavalos/microbiologia , Humanos , Melioidose/diagnóstico , Melioidose/genéticaRESUMO
AIM: Analysis of genetic heterogeneity of Pseudomonas aeruginosa strains isolated in and out of hospitals. MATERIALS AND METHODS: To study the genetic diversity of 36 strains of P. aeruginosa plasmid analysis, random amplified polymorphic DNA (RAPD) technique as well as polymerase chain reaction for detection of virulence genes algD, lasB, toxA, plcH, plcN, exoS, nan1, and nan2. RESULTS: Epidemically important strains were found in different ecological niches. It was shown that these virulence factors could play important roles in pathogenesis of infection. CONCLUSION: RAPD technique was effective for analysis of P. aeruginosa isolates. Number of studied typing bands differed between related isolates for each random primer.
Assuntos
Infecções por Pseudomonas/epidemiologia , Pseudomonas aeruginosa/genética , Primers do DNA , Humanos , Plasmídeos/genética , Reação em Cadeia da Polimerase , Infecções por Pseudomonas/microbiologia , Pseudomonas aeruginosa/classificação , Pseudomonas aeruginosa/isolamento & purificação , Técnica de Amplificação ao Acaso de DNA Polimórfico , Federação Russa/epidemiologia , Sensibilidade e Especificidade , População Urbana , Fatores de Virulência/genéticaRESUMO
Two pairs of primers for diagnosis of coccidioidomycosis using the method of PCR were constructed. One pair was used for identification of the two species of Coccidioides (C. immitis and C. posadasil) on the basis of MBP-1 gene. The other pair was chosen on the basis of SOWgp82 gene, which encodes an immunodominant, spherule outer wall glycoprotein for detecting only C. posadasii. The used primers allowed the agents of coccidioidomycosis to be detected using PCR with high sensitivity and specificity. The effective method of isolation of fungus DNA from soil contaminated with arthroconidia of Coccidioides spp. was developed. It includes guanidinthiocyanate-phenol-chloroform deproteinization followed by DNA purification using nuclear sorption.
Assuntos
Antígenos de Fungos/genética , Coccidioides/isolamento & purificação , Coccidioidomicose/diagnóstico , Glicoproteínas de Membrana/genética , Reação em Cadeia da Polimerase/métodos , Coccidioides/genética , Coccidioidomicose/microbiologia , Primers do DNA/genética , DNA Fúngico/análise , Genes Fúngicos , HumanosRESUMO
Burkholderia mallei is highly pathogenic microorganism for both humans and animals. In this work, the possibility of the use of the genotyping method for differentiation between strains of B. mallei was studied. A collection of 14 isolates of B. mallei was characterized using randomly amplified polymorphic DNA (RAPD) and multilocus sequence typing (MLST). RAPD was the best method used for detecting strain differences of B. mallei. It was suggested that this method would be an increasingly useful molecular epidemiological tool.