Chemical composition and structure of cell wall teichoic acids of staphylococci

The cell wall teichoic acid structures of 22 staphylococci including 13 type strains were determined. Most of the strains contain a poly(polyolphosphate) teichoic acid with glycerol and/or ribitol as polyol component. The polyolphosphate backbone is partially substituted with various combinations of sugars and/or amino sugars. Most of the substituents occur in a monomeric form but some strains also contain dimers of N-acetylglucosamine as substituents. Staphylococcus hyicus subsp. hyicus NCTC 10350 and S. sciuri DSM 20352 revealed rather complex cell wall teichoic acids. They consist of repeating sequences of phosphate-glycerol-phosphate-N-acetylglucosamine. The amino sugar component is present in this case as a monomer or an oligomer (n less than or equal to 3). Moreover, the glycerol residues are partially substituted with N-acetylglucosamine. The cell wall teichoic acid of S. auricularis is a poly(N-acetylglucosaminyl-phosphate) polymer similar to that found in S. caseolyticus ATCC29750. The cell wall teichoic acid structures for type strains of S. auricularis, S. capitis, S. cohnii, S. haemolyticus, S. hominis, S. hyicus subsp. hyicus, S. sciuri, S. xylosus and S. warneri were determined for the first time in detail. The structures of some of the previously described teichoic acids had to be revised (S. epidermidis, S. simulans, S. aureus phage type 187).     

Volume-dependent regulation of ion transport and membrane phosphorylation in human and rat erythrocytes

Summary Osmotic swelling of human and rat erythrocytes does not induce regulatory volume decrease. Regulatory volume increase was observed in shrunken erythrocytes of rats only. This reaction was blocked by the inhibitors of Na⁺/H⁺ exchange. Cytoplasmic acidification in erythrocytes of both species increases the amiloride-inhibited component of²²Na influx by five- to eight-fold. Both the osmotic and isosmotic shrinkage of rat erythrocytes results in the 10- to 30-fold increase of amiloride-inhibited²²Na influx and a two-fold increase of furosemide-inhibited⁸⁶Rb influx. We failed to indicate any significant changes of these ion transport systems in shrunken human erythrocytes. The shrinking of quin 2-loaded human and rat erythrocytes results in the two- to threefold increase of the rate of⁴⁵Ca influx, which is completely blocked by amiloride. The dependence of volume-induced²²Na influx in rat erythrocytes and⁴⁵Ca influx in human erythrocytes on amiloride concentration does not differ. The rate of⁴⁵Ca influx in resealed ghosts was reduced by one order of magnitude when intravesicular potassium and sodium were replaced by choline. It is assumed that the erythrocyte shrinkage increases the rate of a nonselective Ca _o ²⁺ (Na _i ⁺ , K _i ⁺ ) exchange. Erythrocyte shrinking does not induce significant phosphorylation of membrane protein but increases the³²P incorporation in diphosphoinositides. The effect of shrinkage on the³²P labeling of phosphoinositides is diminished after addition of amiloride. It is assumed that volume-induced phosphoinositide response plays an essential role in the mechanism of the activation of transmembrane ion movements.     

Human papillomavirus type 48.

The cloning and partial characterization of the genome of human papillomavirus (HPV) type 48 is presented. Hybridization and short DNA sequence analyses permitted the alignment of the genome to the HPV genetic map.     

Ecotoxicological contamination processes: Interaction with vegetation (a review)

Up-to-date crop production concentrates on the maximisation of plant matter production, both by optimum utilization of solar energy by plants and by the application of additional energy. Therefore a natural strategy is being developed aimed at combining the physiological functions of the assimilation organs with their external shaping and strengthening their variety in space and area. As demonstrated by many deposition studies, this effect is contradictory to the factors conditioning the low deposition capacity of plant covers. A high level of particle, gas and solution deposition increases the danger of food chain contamination and has a negative impact on plant production. Data concentrated on transport values of pollutants and their long-term dynamics in stands could be used for the selection of ideal crop types; therefore every effort should be directed towards selection and breeding.     

Lipid Composition in Scrapie-Infected Mouse Brain: Prion Infection Increases the Levels of Dolichyl Phosphate and Ubiquinone

Abstract: The neutral and phospholipid composition of mouse brain infected with scrapie prions was investigated. During the later stages of this disease, the level of dolichol decreased by 30% whereas the level of dolichyl phosphate increased by 30%. In terminally ill mice, there was also a 2.5-fold increase in both total ubiquinone and its reduced form. Furthermore, α-tocopherol was elevated at this stage by 50%. In contrast, no changes were observed in phospholipid amount, in phospholipid composition, and in phosphatidylethanolamine plasmalogen content during the entire disease process. The fatty acid and aldehyde composition of individual phospholipids remained unaltered as well. No modifications could be detected in cholesterol content. Thus, the majority of membrane lipids in scrapie-infected mouse brain are modified in neither quantity nor structure, but specific changes occur to a few polyisoprenoid lipids. This specificity indicates that, although prions accumulate in lysosomes, the infection process is not associated with a general membrane destruction caused by lysosomal enzyme leakage.     

Host-plant relationships of lycaenid butterflies: large-scale patterns, interactions with plant chemistry, and mutualism with ants

The Lycaenidae are the second-largest family of butterflies. From host-plant data collated for more than 1200 species worldwide, large-scale taxonomic, geographical and ecological patterns emerge which suggest that phytochemical similarities and barriers, coupled with phylogenetic conservatism and constraints are key factors governing hostplant use. More than two thirds of the lycaenid species are restricted to one plant family or genus. Affiliations with toxic plants are rare in the Lycaenidae, and excretion rather than sequestration of plant toxins appears to be their usual way of detoxifying host-plant compounds. Flavonoids are frequently sequestered by lycaenid larvae and are subsequently concentrated as pigments in the adults' wings, where they might play a role in visual communication. Mutualistic associations with ants occur in the larvae of more than 50% of the extant Lycaenidae species. Because of a conflict between the nutrient demands of the larvae and the proportion of plant-derived resources allocated to maintain the mutualism with ants, variation in resource quality often translates into variation of mutualistic capacities of the caterpillars, in particular under nutrient stress.     

VIP36, a novel component of glycolipid rafts and exocytic carrier vesicles in epithelial cells.

In simple epithelial cells, apical and basolateral proteins and lipids in transit to the cell surface are sorted in the trans-Golgi network. We have recently isolated detergent-insoluble complexes from Madin-Darby canine kidney cells that are enriched in glycosphingolipids, apical cargo and a subset of the proteins of the exocytic carrier vesicles. The vesicular proteins are thought to be involved in protein sorting and include VIP21-caveolin. The vesicular protein VIP36 (36 kDa vesicular integral membrane protein) has been purified from a CHAPS-insoluble residue and a cDNA encoding VIP36 has been isolated. The N-terminal 31 kDa luminal/exoplasmic domain of the encoded protein shows homology to leguminous plant lectins. The transiently expressed protein is localized to the Golgi apparatus, endosomal and vesicular structures and the plasma membrane, as predicted for a protein involved in transport between the Golgi and the cell surface. It is diffusely localized on the plasma membrane but can be redistributed by antibody modulation into caveolae and clathrin-coated pits. We speculate that VIP36 binds to sugar residues of glycosphingolipids and/or glycosylphosphatidyl-inositol anchors and might provide a link between the extracellular/luminal face of glycolipid rafts and the cytoplasmic protein segregation machinery.     

Characterization of devA, a gene required for the maturation of proheterocysts in the cyanobacterium Anabaena sp. strain PCC 7120.

Mutant M7, obtained by transposon mutagenesis of the cyanobacterium Anabaena sp. strain PCC 7120, is impaired in the development of mature heterocysts. Under aerobic conditions, the mutant is unable to fix N2 because of a deficiency of at least two components of the oxygen-protective mechanisms: a hemoprotein-coupled oxidative reaction and heterocyst-specific glycolipids. DNA contiguous with the inserted transposon was recovered from the mutant and sequenced. The transposon had inserted itself within a 732-bp open reading frame designated devA. The wild-type form of devA, obtained from a lambda-EMBL3 library of Anabaena sp. DNA, had the identical sequence. Directed mutagenesis of devA in the wild-type strain showed that the phenotype of the mutant was caused by insertion of the transposon. The wild-type form of devA on a shuttle vector complemented the mutation in M7. Expression of devA by whole filaments, monitored following nitrogen stepdown by using luxAB as the reporter, increased ca. eightfold during differentiation; the increase within differentiating cells was much greater. The deduced sequence of the DevA protein shows strong similarity to the ATP-binding subunit of binding protein-dependent transport systems. The product of devA may, therefore, be a component of a periplasmic permease that is required for the transition from a proheterocyst to a mature, nitrogen-fixing heterocyst.