Polymorphism, genetic exchange and intragenic recombination of the aureolysin gene among Staphylococcus aureus strains

<p>Abstract</p> <p>Background</p> <p><it>Staphylococcus aureus </it>expresses several proteases, which are thought to contribute to the virulence of this bacterium. Here we focus on aureolysin, the major thermolysin-like metalloprotease. Despite the importance of aureolysin in the physiology and pathogenesis of <it>S. aureus</it>, relatively little information was so far available concerning the <it>aur </it>gene diversity and mobility within and between the major subdivisions of the <it>S. aureus </it>population. Therefore, an epidemiologically and genetically diverse collection of <it>S. aureus </it>strains was used to determine the range of aureolysin (<it>aur</it>) gene polymorphism.</p> <p>Results</p> <p>Sequence analyses support the conclusion that the <it>aur </it>gene occurs in two distinct types of related sequences. The <it>aur </it>gene was much more polymorphic but, at the same time, showed higher purifying selection than genes utilized for multilocus sequence typing (MLST). Gene trees constructed from <it>aur </it>and concatenated MLST genes revealed several putative assortative recombination events (<it>i.e</it>. entire <it>aur </it>gene exchanges) between divergent lineages of <it>S. aureus</it>. Evidence for intragenic recombination events (<it>i.e</it>. exchanges of internal <it>aur </it>segments) across <it>aur </it>genes was also found. The biochemical properties and substrate specificity of the two types of aureolysin purified to homogeneity were studied, revealing minor differences in their affinity to low molecular weight synthetic substrates.</p> <p>Conclusion</p> <p>Although numerous nucleotide differences were identified between the <it>aur </it>alleles studied, our findings showed that a strong purifying selection is acting on the <it>aur </it>gene. Moreover, our study distinguishes between homologous exchanges of the entire <it>aur </it>gene (assortative recombination) between divergent <it>S. aureus </it>lineages and recombination events within <it>aur </it>genes.</p

COVID-19 vaccination in patients receiving allergen immunotherapy (AIT) or biologicals:EAACI recommendations

Immune modulation is a key therapeutic approach for allergic diseases, asthma and autoimmunity. It can be achieved in an antigen-specific manner via allergen immunotherapy (AIT) or in an endotype-driven approach using biologicals that target the major pathways of the type 2 (T2) immune response: immunoglobulin (Ig)E, interleukin (IL)-5 and IL-4/IL-13 or non-type 2 response: anti-cytokine antibodies and B-cell depletion via anti-CD20. Coronavirus disease 2019 (COVID-19) vaccination provides an excellent opportunity to tackle the global pandemics and is currently being applied in an accelerated rhythm worldwide. The vaccine exerts its effects through immune modulation, induces and amplifies the response against the severe acute respiratory syndrome coronavirus (SARS-CoV-2). Thus, as there may be a discernible interference between these treatment modalities, recommendations on how they should be applied in sequence are expected. The European Academy of Allergy and Clinical Immunology (EAACI) assembled an expert panel under its Research and Outreach Committee (ROC). This expert panel evaluated the evidence and have formulated recommendations on the administration of COVID-19 vaccine in patients with allergic diseases and asthma receiving AIT or biologicals. The panel also formulated recommendations for COVID-19 vaccine in association with biologicals targeting the type 1 or type 3 immune response. In formulating recommendations, the panel evaluated the mechanisms of COVID-19 infection, of COVID-19 vaccine, of AIT and of biologicals and considered the data published for other anti-infectious vaccines administered concurrently with AIT or biologicals

Software-Defined Computer with a Classic Microprocessor

The paper describes the concept and the design process of a software-defined computer built for didactic purposes and as a proof-of-concept. The computer uses a classic microprocessor from the 1980s with all of its other components – memory, I/O, supplementary glue logic and a hardware bus monitor implemented with a contemporary mainstream microcontroller with Cortex-M family core. The concept of a software-defined computer was successfully implemented with four significantly different microprocessors. The computer may be used for illustrating the operation of a processor and for teaching the basics of low-level programming. It is also capable of running CP/M operating system. Its operation is controlled at both hardware and software level from a PC via two instances of a terminal emulator software

Graphene oxide and green-synthesized reduced graphene oxide in chitosanbased nanocomposites

The first part of the paper concerns synthesis and characterization of two types of nanomaterials: graphene oxide (GO) prepared by modified Marcano method and reduced graphene oxide (rGO) synthesized using green reductant, L-ascorbic acid. Their structural properties were investigated by attenuated total reflection Fourier-transform infrared spectroscopy (ATR-FTIR) and X-ray diffraction (XRD). Results confirmed that L-ascorbic acid is an effective reducing agent. Intensity of the oxygen-groups decreased dramatically what resulted in reduction of the GO interlayer spacing from 0.8 nm to 0.4 nm. The second part of the research was concentrated on the properties of chitosan nanocomposites modified with GO and rGO. Films were prepared by mixing of the chitosan solution with the nanoparticles dispersion. Scanning electron microscopy (SEM) was used to investigate the microstructure of the composites surface. In addition, wettability and pore size of the freeze-dried scaffolds were evaluated. Results of the mechanical tests (increase in Young’s modulus) and structural characterization confirmed that chitosan solution and GO dispersion can be mixed homogeneously. Reduction of GO during composite synthesis resulted in better dispersion of the nanosheets what increased surface roughness, wettability and stability in distilled water, PBS and Ringer’s solution compared to composite with GO. After detailed biological examination, rGO-modified nanocomposites can be potentially applied in tissue engineering

Rzeczka Bukowa w aglomeracji miejskiej Szczecina - od zrodel na bezrzeczu do ujscia do Odry - badania biologiczne i chemiczne

W okresie jesień 1999 - wiosna 2000 prowadzono badania ekosystemu cieku - strumienia Bukowa przepływającego przez aglomerację miejską Szczecina. Zebrane dane umożliwiły dokonanie opisu fizjograficznego rzeki Bukowej oraz ocenę stanu fito- i zoocenoz tego cieku, a także dokonanie oceny jakości wód rzeki wzdłuż drogi ich spływu. Wyniki badań biologicznych i chemicznych wykazały, że ciek - strumień Bukowa, począwszy od źródła w dzielnicy Bezrzecze, aż do ujścia do rzeki Odry, jest właściwie kanałem, którym spływają martwe biologicznie i - mierząc według kryteriów chemicznych - zdeklasowane wody, przeważnie pochodzenia ściekowego.The ecosystem of Bukowa stream, flowing across the Szczecin agglomeration, was investigated within the period of autumn 1999 - spring 2000. The data collected made possible to accomplish the Bukowa physiographical description, to asses the phyto- and zoocenose conditions and to evaluate the water quality in Bukowa, along the couse of flow. Results of biological and chemical investigations showed, that Bukowa-stream, from the spring at Bezrzecze quarter to Odra River mouth, is in fact sewer, with flowing of biologicaly dead and declassified water, mostly of sewage origin