Biosynthesis of lipopolysaccharides with different length of the O-specific region as a virulence factor of Gram-negative bacteria

The outer membrane of Gram-negative bacteria is a biological structure with a unique composition that significantly contributes to the survival of bacteria in the unfavorable conditions of the host organism. The lipopolysaccharide constitutes about 70% of the external part of the outer membrane. The LPS molecule is composed of three different parts: lipid A, core oligosaccharide and O antigen. Despite the O-specific antigen being one of the most intensely studied surface structures of bacterial polysaccharides, a number of questions regarding the mechanism of the O antigen biosynthesis and its transport to the cell surface are still unanswered. The paper describes the biosynthesis of the lipopolysaccharide molecule, with particular emphasis on the O-specific chain biosynthesis, the mechanism of lipopolysaccharide length regulation and the influence of the type of synthesized O-specific chains on bacterial survival in adverse host organisms

In-Orbit Instrument Performance Study and Calibration for POLAR Polarization Measurements

POLAR is a compact space-borne detector designed to perform reliable measurements of the polarization for transient sources like Gamma-Ray Bursts in the energy range 50-500keV. The instrument works based on the Compton Scattering principle with the plastic scintillators as the main detection material along with the multi-anode photomultiplier tube. POLAR has been launched successfully onboard the Chinese space laboratory TG-2 on 15th September, 2016. In order to reliably reconstruct the polarization information a highly detailed understanding of the instrument is required for both data analysis and Monte Carlo studies. For this purpose a full study of the in-orbit performance was performed in order to obtain the instrument calibration parameters such as noise, pedestal, gain nonlinearity of the electronics, threshold, crosstalk and gain, as well as the effect of temperature on the above parameters. Furthermore the relationship between gain and high voltage of the multi-anode photomultiplier tube has been studied and the errors on all measurement values are presented. Finally the typical systematic error on polarization measurements of Gamma-Ray Bursts due to the measurement error of the calibration parameters are estimated using Monte Carlo simulations.Comment: 43 pages, 30 figures, 1 table; Preprint accepted by NIM

latka.p65

Abstract. Intermetallic REAuSn (RE = rare earth elements) compounds were studied by means of X-ray diffraction (XRD), magnetic measurements and 119 Sn Mössbauer spectroscopy. It was shown that the majority of them exhibit complex antiferromagnetic ordering at low temperatures. The nature of hyperfine interactions has been discussed based on γ-ray absorption spectroscopy together with magnetic and structural data. Lanthanide contraction is reflected in the lattice parameters and isomer shifts. Strong experimental arguments support correlation between crystallographic type of structure and magnetic disordering in investigated compounds

Specific Alteration of Branched-Chain Amino Acid Profile in Polycystic Ovary Syndrome

Polycystic ovary syndrome (PCOS) is one of the most common endocrinopathies in reproductive age women; it is a complex health issue with numerous comorbidities. Attention has recently been drawn to amino acids as they are molecules essential to maintain homeostasis. The aim of the study was to investigate the branch chain amino acid (BCAA) profile in women with PCOS. A total of 326 women, 208 diagnosed with PCOS and 118 healthy controls, participated in the study; all the patients were between 18 and 40 years old. Anthropometrical, biochemical and hormonal parameters were assessed. Gas-liquid chromatography combined with tandem mass spectrometry was used to investigate BCAA levels. Statistical analysis showed significantly higher plasma levels of BCAAs (540.59 ± 97.23 nmol/mL vs. 501.09 ± 85.33 nmol/mL; p p < 0.05) were found between BCAA and BMI, HOMA-IR, waist circumference and total testosterone levels. In the analysis of individuals with abdominal obesity, there were significant differences between PCOS and controls in BCAA (558.13 ± 100.51 vs. 514.22 ± 79.76 nmol/mL) and the concentrations of all the analyzed amino acids were higher in the PCOS patients. Hyperandrogenemia in PCOS patients was associated with significantly higher leucine, isoleucine and total BCAA levels. The increase of BCAA levels among PCOS patients in comparison to healthy controls might be an early sign of metabolic alteration and a predictive factor for other disturbances

Salmonella O48 Serum Resistance is Connected with the Elongation of the Lipopolysaccharide O-Antigen Containing Sialic Acid

Complement is one of the most important parts of the innate immune system. Some bacteria can gain resistance against the bactericidal action of complement by decorating their outer cell surface with lipopolysaccharides (LPSs) containing a very long O-antigen or with specific outer membrane proteins. Additionally, the presence of sialic acid in the LPS molecules can provide a level of protection for bacteria, likening them to human cells, a phenomenon known as molecular mimicry. Salmonella O48, which contains sialic acid in the O-antigen, is the major cause of reptile-associated salmonellosis, a worldwide public health problem. In this study, we tested the effect of prolonged exposure to human serum on strains from Salmonella serogroup O48, specifically on the O-antigen length. After multiple passages in serum, three out of four tested strains became resistant to serum action. The gas-liquid chromatography/tandem mass spectrometry analysis showed that, for most of the strains, the average length of the LPS O-antigen increased. Thus, we have discovered a link between the resistance of bacterial cells to serum and the elongation of the LPS O-antigen

Chlorophyll a fluorescence in evaluation of the effect of heavy metal soil contamination on perennial grasses.

Chlorophyll a fluorescence gives information about the plant physiological status due to its coupling to the photosynthetic electron transfer chain and to the further biochemical processes. Environmental stresses, which acts synergistically, disturbs the photosynthesis. The OJIP test, elaborated by Strasser and co-workers, enables comparison of the physiological status of plants grown on polluted vs. control areas. The paper shows that the Chl a measurements are very useful tool in evaluating of heavy metal ions influence on perennial grasses, tested as potential phytoremediators. Among 5 cultivars tested, the highest concentration of Cd and Zn ions, not associated with the yield reduction, was detected in the biomass of tall fescue cv. Rahela. Chl a fluorescence interpreted as double normalized curves pointed out Rahela as the outstanding cultivar under the HM ions stress

Application of supercritical carbon dioxide(scCO(2))for the extraction of lipopolysaccharides (LPS) from Salmonella enterica subsp enterica PCM 2266

The paper describes a novel extraction procedure for lipopolysaccharides (LPS) from Salmonella enterica subsp. enterica (PCM 2266). Process parameters for the extraction of LPS from bacterial mass were optimized by carrying out a two-level fractional design experiment. Four parameters, namely temperature, CO2 flow rate, pressure and co-solvent composition were analyzed. The best crude extract yields were achieved when the CO2 flow rate and temperature were kept high (10 g/min, 90 degrees C) and pure water was used as a co-solvent. Pressure had no statistically significant effect within the range of the study performed, whereas the other factors were relevant. The recovery of the extracted LPS by scCO(2) was about 3.3% of the biomass used, while in the classical extraction method yield was less than 2%. All isolates were characterized by SDS-PAGE, by the spectra of the thiobarbituric acid reaction products and GLC-MS analysis