Variation of Neisseria gonorrhoeae Lipooligosaccharide Directs Dendritic Cell–Induced T Helper Responses

Gonorrhea is one of the most prevalent sexually transmitted diseases in the world. A naturally occurring variation of the terminal carbohydrates on the lipooligosaccharide (LOS) molecule correlates with altered disease states. Here, we investigated the interaction of different stable gonoccocal LOS phenotypes with human dendritic cells and demonstrate that each variant targets a different set of receptors on the dendritic cell, including the C-type lectins MGL and DC-SIGN. Neisseria gonorrhoeae LOS phenotype C constitutes the first bacterial ligand to be described for the human C-type lectin receptor MGL. Both MGL and DC-SIGN are locally expressed at the male and female genital area, the primary site of N. gonorrhoeae infection. We show that targeting of different C-type lectins with the N. gonorrhoeae LOS variants results in alterations in dendritic cell cytokine secretion profiles and the induction of distinct adaptive CD4⁺ T helper responses. Whereas N. gonorrhoeae variant A with a terminal N-acetylglucosamine on its LOS was recognized by DC-SIGN and induced significantly more IL-10 production, phenotype C, carrying a terminal N-acetylgalactosamine, primarily interacted with MGL and skewed immunity towards the T helper 2 lineage. Together, our results indicate that N. gonorrhoeae LOS variation allows for selective manipulation of dendritic cell function, thereby shifting subsequent immune responses in favor of bacterial survival.     

Distinct subcellular localization in the cytosol and apicoplast,unexpected dimerization and inhibition of Plasmodium falciparum glyoxalases

The ubiquitous glyoxalase system removes methylglyoxal as a harmful by‐product of glycolysis. Because malaria parasites have drastically increased glycolytic fluxes, they could be highly susceptible to the inhibition of this detoxification pathway. Here we analysed the intracellular localization, oligomerization and inhibition of the glyoxalases from Plasmodium falciparum. Glyoxalase I (GloI) and one of the two glyoxalases II (cGloII) were located in the cytosol of the blood stages. The second glyoxalase II (tGloII) was detected in the apicoplast pointing to alternative metabolic pathways. Using a variety of methods, cGloII was found to exist in a monomer–dimer equilibrium that might have been overlooked for homologues from other organisms and that could be of physiological importance. The compounds methyl‐gerfelin and curcumin, which were previously shown to inhibit mammalian GloI, also inhibited P. falciparum GloI. Inhibition patterns were predominantly competitive but were complicated because of the two different active sites of the enzyme. This effect was neglected in previous inhibition studies of monomeric glyoxalases I, with consequences for the interpretation of inhibition constants. In summary, the present work reveals novel general glyoxalase properties that future research can build on and provides a significant advance in characterizing the glyoxalase system from P. falciparum.     

Carotenoid fluorescence in <Emphasis Type="Italic">Dunaliella salina</Emphasis>

Dunaliella salina is a halotolerant green alga that is well known for its carotenoid producing capacity. The produced carotenoids are mainly stored in lipid globules. For various research purposes, such as production and extraction kinetics, we would like to determine and/or localise the carotenoid globules in vivo. In this study, we show that the carotenoid-rich globules emit clear green fluorescence, which can be used in, for example, fluorescence microscopy (e.g. CLSM) to obtain pictures of the cells and their carotenoid content.     

The majority of the genetic risk for Paget’s disease of bone is explained by genetic variants close to the CSF1, OPTN, TM7SF4, and TNFRSF11A genes

Paget’s disease of bone (PDB) is one of the most frequent metabolic bone disorders (1–5%), next to osteoporosis, affecting individuals above age 55. Sequestosome1 mutations explain a part of the PDB patients, but still the disease pathogenesis in the remaining PDB patients is largely unknown. Therefore, association studies investigating the relationship between genetic polymorphisms and sporadic PDB have been performed to find the genetic risk variants. Previously such studies indicated a role of the OPG and RANK gene. The latter was recently confirmed in a genome-wide association study (GWAS) which also indicated the involvement of chromosomal regions harbouring the CSF1 and OPTN gene. In this study, we sought to replicate these findings in a Belgian and a Dutch population. Similar significant results were obtained for the single nucleotide polymorphisms and the haplotypes. The most significant results are found in the CSF1 gene region, followed by the OPTN and TNFRSF11A gene region (p values ranging from 1.3 × 10^?4 to 3.8 × 10^?8, OR = 1.523–1.858). We next obtained significant association with a polymorphism from the chromosomal region around the TM7SF4 gene (p = 2.7 × 10^?3, OR = 1.427), encoding DC-STAMP which did not reach genome-wide significance in the GWAS, but based on its function in osteoclasts it can be considered a strong candidate gene. After meta-analysis with the GWAS data, p values ranged between 2.6 × 10^?4 and 8.8 × 10^?32. The calculated cumulative population attributable risk of these four loci turned out to be about 67% in our two populations, indicating that most of the genetic risk for PDB is coming from genetic variants close to these four genes.     

Screening of Bacterial Isolates from Polluted Soils Exhibiting Catalase and Peroxidase Activity and Diversity of their Responses to Oxidative Stress

For the survival of individual isolates of gram-negative bacteria Pseudomonas putida, Achromobacter xylosoxidans, and the gram-positive bacterium Bacillus megaterium, in an environment polluted with crude oil products, the production of catalases exhibiting both catalase and dianisidine-peroxidase activity is important. Electrophoretic resolution of cell-free extracts of aerobically grown strains in Luria–Bertani medium during exponential phase revealed distinctive expression of catalatic and peroxidatic activities detected with 3,3′-diaminobenzidine tetrahydrochloride. A considerable diversity in microbial catalase and peroxidase responses to 20 or 40 mM H₂O₂ stress, resulted from hydroperoxidase’s variant of original isolates, indicating an environmental selective pressure. However, catalase was important for the adaptation of cultures to high concentration of 60 mM H₂O₂. Appreciable differences in the sensitivity to toxic effect of H₂O₂ (20 or 40 mM) treatment between individual isolates and their adapted variants during growth were observed until the middle of exponential phase, but they were insignificant at the entry to stationary phase. Isolates also exhibited a considerable diversity in catalases responses to phenolic contaminants 1 and 2 mM o- or p-phenylenediamine. Catalase activity of bacterium P. putida was visibly stimulated only by p-phenylenediamine and not by its positional isomer o-PDA. This study contributes to a better understanding of the role catalases play in bacterial responses to a polluted environment.     

An Inhibitor of Tryptophan-Dependent Biosynthesis of Indole-3-Acetic Acid Alters Seedling Development in Arabidopsis

Although polar transport and the TIR1-dependent signaling pathway of the plant hormone auxin/indole-3-acetic acid (IAA) are well characterized, understanding of the biosynthetic pathway(s) leading to the production of IAA is still limited. Genetic dissection of IAA biosynthetic pathways has been complicated by the metabolic redundancy caused by the apparent existence of several parallel biosynthetic routes leading to IAA production. Valuable complementary tools for genetic as well as biochemical analysis of auxin biosynthesis would be molecular inhibitors capable of acting in vivo on specific or general components of the pathway(s), which unfortunately have been lacking. Several indole derivatives have been previously identified to inhibit tryptophan-dependent IAA biosynthesis in an in vitro system from maize endosperm. We examined the effect of one of them, 6-fluoroindole, on seedling development of Arabidopsis thaliana and tested its ability to inhibit IAA biosynthesis in feeding experiments in vivo. We demonstrated a correlation of severe developmental defects or growth retardation caused by 6-fluoroindole with significant downregulation of de novo synthesized IAA levels, derived from the stable isotope-labeled tryptophan pool, upon treatment. Hence, 6-fluoroindole shows important features of an inhibitor of tryptophan-dependent IAA biosynthesis both in vitro and in vivo and thus may find use as a promising molecular tool for the identification of novel components of the auxin biosynthetic pathway(s).     

Changes in abundance of hibernating bats in central Slovakia (1992–2009)

An analysis of long-term changes in abundance of hibernating bats as revealed from the annual monitoring programme conducted in four mountain regions of the Western Carpathians (Muránska planina Mts, Revúcka vrchovina Mts, Slovensky kras Mts, Štiavnické vrchy Mts) during the period 1992–2009 is providing in the paper. Data from 52 hibernacula were analysed. Among 18 bat species recorded, an apparent population increase of three most abundant thermophilous and originally cave dwelling species of bats, Rhinolophus hipposideros, R. ferrumequinum, Myotis myotis, was observed. In other bat species (e.g., R. euryale, M. emarginatus, M. mystacinus, M. dasycneme, Barbastella barbastellus), population trends could not be detected and because of data scarcity, they should be evaluated from more extensive datasets obtained from a wide range of hibernacula or from a completely different type of evidence.