Expression and secretion of outer surface protein (OSP-A) of Borrelia burgdorferi from Escherichia coli

Abstract Outer surface protein A (OspA) is encoded by the ospA gene from Borrelia burgdorferi . This protein induces immunity against infection in mice. The cloning and expression of OspA in Escherichia coli have been previously described, but the secretion of OspA into culture media in E. coli has not yet been reported. In this report we demonstrate that a chimeric OspA protein was secreted into culture media by E. coli when it also harbors the hemolysin secretion genes hlyBD . The OspA fusion protein was also overexpressed from a T7 promoter and purified by immobilized metal ion chromatography. This was possible because the fusion protein contains ix histidyl residues in its N-terminus.     

Cellular and subcellular immunolocalization of L-glutamate decarboxylase in rat pancreatic islets

The cellular and subcellular distribution of L-glutamate decarboxylase (GAD), the biosynthetic enzyme for gamma-aminobutyric acid (GABA), was determined immunohistochemically in rat pancreatic islet using light and electron microscopic techniques. The cellular distribution of GAD was determined at the light microscopic level using an elution/re-staining protocol and a computerized digital image processing technique. At this level of resolution, immunofluorescent GAD was observed to be co-localized with immunofluorescent insulin in the islet B-cells and absent in both the A-cells, which contained glucagon, and the D-cells, which contained somatostatin. Subcellular localization of GAD was determined using an electron microscopic, colloidal gold post-embedding protocol and was compared to insulin immunoreactivity in serial sections of the same B-cell. In the same islet B-cell, GAD immunoreactivity appeared predominantly in the extragranular cytoplasm, whereas insulin immunoreactivity was associated with the secretory granules. Quantitative analysis of GAD immunoreactivity in the B-cell revealed 15.3 +/- 1.8 gold particles/micron2 in the cytoplasm, 1.7 +/- 0.2 gold particles/micron2 in the secretory granules, and 0.4 +/- 0.4 gold particles/micron2 in the mitochondria. The results of this study, localization of the biosynthetic enzyme for GABA to the B-cell cytoplasmic compartment and its absence in the secretory granules which contain insulin, are compatible with the hypothesis that GABA functions as an intracellular mediator of B-cell activity.     

Effects of temperature on nutrient self‐selection in the silverfish Lepisma saccharina

Nutrient self‐selection represents an important behaviour that has been measured across many taxa. Despite the amount of research on this phenomenon, few studies report the evaluation of the effects of environmental variables such as temperature on nutrient selection by animals. In the present study, the nutrient selections of the silverfish Lepisma saccharina L. are measured across a range of temperatures (10, 15, 20, 25, 30 and 35 °C) using feeding arenas with three nutrient choices: carbohydrate (sucrose), protein (casein) and fat (lard). An overall preference for carbohydrates is shown across the range of temperatures, followed by protein, and then fat. However, the proportional consumption of each dietary component changes with temperature; the proportional carbohydrate consumption decreases dramatically with increasing temperature (>94% of the diet at 15 °C but <58% at 30 °C), whereas the proportional protein and lipid consumption increases with increasing temperature up to 30 °C. Changes in nutrient selection with temperature may be related to the dietary requirements of the insect at different temperatures.     

Antimalarial and cytotoxic activities of chiral triamines

Chiral triamine antimalarial compounds have been identified following the screening of mixture-based positional scanning libraries made up of 31,320 compounds against P. falciparum. The library, namely N-methyl triamine (TPI 762) was generated following exhaustive reduction of resin-bound acylated dipeptides. Using the PSCL approach, individual compounds were rapidly identified which were only 10 times less active than the standard drugs chloroquine (CQ) and Artemisinin (Artes).     

Morphologie des épines chez les brachiopodes Delthyrididae

Two main types of micro-ornament can be observed in the family Delthyrididae (Brachiopoda, Spiriferidina): capillae (with continuity of the structures from one growth lamella to the next one) and spines (with the appearance of discontinuity). SEM studies of the spines show that, contrary to previous assumption, the cross section is not circular but subquadrangular with a longitudinal groove on top. Each spine is connected in front to the next one so that they give rise to a continuous radial structure. Thus the spine is a local external differentiation of the underlying microfila. Furthermore, the spinose ornament is derived from the capillate ornament. During growth, new fila and spines appear in the grooves and diverge towards the top of adjacent costae, running across several lamellae. When there are few spines, they have a uniform size, but when there are many spines, small spines (issued from newer fila) are juxtaposed with large spines (issued from older fila). The use of micro-ornament in systematics has often been based on misinterpretations; attention is drawn to the fact that the shape of the spine base is not representative of the original shape of the spine but generally resulted from the erosion of the shell. Nevertheless, more detailed studies on spine shape and arrangement offer interesting prospects for classification.     

The SWISS-2DPAGE database: what has changed during the last year.

SWISS-2DPAGE (http://www.expasy.ch/ch2d/) is an annotated two-dimensional polyacrylamide gel electrophoresis (2-D PAGE) database established in 1993. The current release contains 21 reference maps from human and mouse biological samples, as well as from Saccharomyces cerevisiae, Escherichia coli and Dictyostelium discoideum origin. These reference maps now have 2480 identified spots, corresponding to 528 separate protein entries in the database, in addition to virtual entries for each SWISS-PROT sequence. During the last year, the SWISS-2DPAGE has undergone major changes. Six new maps have been added, and new functions to access the data have been provided through the ExPASy server. Finally, an important change concerns the database funding source.     

The TatAd component of the Bacillus subtilis twin-arginine protein transport system forms homo-multimeric complexes in its cytosolic and membrane embedded localisation

The twin arginine translocation (Tat) system has the capacity to transfer completely folded proteins across the bacterial cytoplasmic membrane and the thylakoid membrane of plant chloroplasts. The most abundant TatA protein of this system has been suggested to form the protein conducting channel. Here, the molecular organisation of soluble and membrane embedded Bacillus subtilis TatA_d was analysed using negative contrast and freeze-fractured electron microscopy. In both compartments, the protein showed homo-oligomerisation. In aqueous solution, TatA_d formed homo-multimeric micelle-like complexes. Freeze-fracture analysis of proteoliposomes revealed self association of membrane-integrated TatA_d independent from TatC_d, the second component of this transport system. Immunogold labelling demonstrated that the substrate prePhoD was co-localised with membrane-integrated TatA_d complexes.