Search

Intravascular nematodes were considered the cause of death of 14 captive callitrichids. All animals were captive born at zoos in France and died with little or no premonitory signs of disease. No consistent gross lesions were observed at necropsy, although in certain cases intracardiac adult parasites were noted. The most significant histologic findings were verminous pneumonia and pulmonary endarteritis. In all cases except one, intravascular adult nematodes were observed with eggs and larvae in the lungs. Adult nematodes were obtained from 8 animals and in all cases were identified as Parastrongylus dujardini. To the authors’ knowledge, this is the first report of intravascular angiostrongylosis with primary cardiopulmonary location in callitrichids in France. [ABSTRACT FROM PUBLISHER]

Background In December 2007, Babesia bovis was introduced to New Caledonia through the importation of cattle vaccinated with a live tick fever (babesiosis and anaplasmosis) vaccine. Medical measures, acaricide and antiprotozoal treatments, and quarantine restrictions were implemented with success on all the farms involved, but the disease spread to one of the neighbouring properties where feral cattle were present. To circumscribe and eliminate this outbreak, the authorities decided to slaughter all animals on the neighbouring property. Objectives To monitor the spread of babesiosis in naïve cattle and to compare the usefulness of PCR, ELISA and brain smear for disease detection in monitoring this outbreak. Methods Blood and brain samples of slaughtered animals were analysed over time throughout the eradication campaign using serology, PCR and brain smears. In addition, field numbers of Rhipicephalus microplus tick larvae were assessed and Babesia infection of the larvae analysed using PCR. Results This study showed the natural spread of babesiosis in a naïve herd without pharmacological control measures. Prevalence reached 80% within a year of introduction. ELISA and PCR tests performed similarly in detecting disease in cattle and both were superior to brain smears. Nevertheless, specific tests or combinations of tests may be preferable, depending on the specific requirements of any future disease situation. Conclusions In cattle, ELISA and PCR appear to be suitable tools for monitoring the evolution of a babesiosis outbreak, with brain smears as a useful adjunct. PCR was not suitable for detecting infection in tick larvae. [ABSTRACT FROM AUTHOR]

Abstract: Ribose-5-phosphate isomerase A has an important role in sugar metabolism by interconverting ribose-5-phosphate and ribulose-5-phosphate. This enzyme is ubiquitous and highly conserved among the three kingdoms of life. We have solved the 2.1 Å resolution crystal structure of the Saccharomyces cerevisiae enzyme by molecular replacement. This protein adopts the same fold as its archaeal and bacterial orthologs with two α/β domains tightly packed together. Mapping of conserved residues at the surface of the protein reveals strong invariability of the active site pocket, suggesting a common ligand binding mode and a similar catalytic mechanism. The yeast enzyme associates as a homotetramer similarly to the archaeal protein. The effect of an inactivating mutation (Arg189 to Lys) is discussed in view of the information brought by this structure. [Copyright &y& Elsevier]

In many cases, antibody and their complexes can be crystallized and their structure determined without major difficulties. The remaining problematic cases may be approached through techniques such as of combinatorial complex crystallization which uses immunoglobulin binding proteins (IBP). The range of lattices that can be made using this method can be expanded by engineering mutants of IBP domains. We have designed Peptostreptococcus magnus protein L (PpL) mutants with altered immunoglobulin light chain binding characteristics. While the wild type PpL has two binding sites, some of the mutants contact the light chain via only one site. Other mutants have combinations of weakened first and second binding sites that modify their crystallization properties and their packing mode. In this study, we have selected PpL mutants with different behavior and that are most useful for crystallization and we present the various packing modes obtained so far. [ABSTRACT FROM AUTHOR]

Abstract: Structural studies of multi-protein complexes, whether by X-ray diffraction, scattering, NMR spectroscopy or electron microscopy, require stringent quality control of the component samples. The inability to produce ‘keystone’ subunits in a soluble and correctly folded form is a serious impediment to the reconstitution of the complexes. Co-expression of the components offers a valuable alternative to the expression of single proteins as a route to obtain sufficient amounts of the sample of interest. Even in cases where milligram-scale quantities of purified complex of interest become available, there is still no guarantee that good quality crystals can be obtained. At this step, protein engineering of one or more components of the complex is frequently required to improve solubility, yield or the ability to crystallize the sample. Subsequent characterization of these constructs may be performed by solution techniques such as Small Angle X-ray Scattering and Nuclear Magnetic Resonance to identify ‘well behaved’ complexes. Herein, we recount our experiences gained at protein production and complex assembly during the European 3D Repertoire project (3DR). The goal of this consortium was to obtain structural information on multi-protein complexes from yeast by combining crystallography, electron microscopy, NMR and in silico modeling methods. We present here representative set case studies of complexes that were produced and analyzed within the 3DR project. Our experience provides useful insight into strategies that are more generally applicable for structural analysis of protein complexes. [Copyright &y& Elsevier]