Immunologic responses and reproductive outcomes following exposure to wild-type or attenuated porcine reproductive and respiratory syndrome virus in swine under field conditions

OBJECTIVE: To compare immunologic responses and reproductive outcomes in sows housed under field conditions following controlled exposure to a wild-type strain of porcine reproductive and respiratory syndrome virus (PRRSV strain WTV) or vaccination with a modified-live virus (MLV) vaccine. DESIGN: Randomized controlled trial. ANIMALS: 30 PRRSV-na?ve 10-week-old female pigs. PROCEDURE: Humoral and cell-mediated immune responses were monitored while pigs were held in isolation for 84 days after inoculation with the WTV strain (n = 10), inoculation with the WTV strain and 42 days later vaccination with a killed-virus vaccine (10), or vaccination with an MLV vaccine (10). Reproductive outcomes were measured after pigs were released into the farm herd. RESULTS: Inoculation with the WTV strain, regardless of whether a killed-virus vaccine was subsequently administered, elicited faster and more substantial production of strain-specific neutralizing antibodies, as well as a more rapid generation of interferon-gamma secreting cells, than did vaccination with the MLV vaccine. Despite the enhanced immune responses in pigs inoculated with the WTV strain, animals vaccinated with the MLV vaccine produced a mean of 2.45 more pigs than did sows exposed to the WTV strain, mainly because of a lower rate for failure to conceive. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that current assays of immunity to PRRSV correlate only imperfectly with degree of clinical protection and that the practice of controlled exposure of sows to a circulating PRRSV strain should be reconsidered in light of negative clinical outcomes.     

Patterns of gastrointestinal bacterial exchange between chimpanzees and humans involved in research and tourism in western Uganda

Ecological overlap may increase the risks of microbial exchange between humans and wild non-human primates. Escherichia coli bacteria were collected from chimpanzees and humans in Kibale National Park, western Uganda, in May and June 2004, in order to examine whether interaction between humans and apes in the wild might affect gastrointestinal bacterial communities in the two species. Chimpanzees harbored bacteria genetically more similar to those of humans employed in chimpanzee-directed research and tourism than to those of humans from a local village. Most humans (81.6%) and 4.4% of chimpanzees harbored at least one isolate resistant to locally available antibiotics. In isolates from both humans and chimpanzees, resistance was higher to five of these antibiotics than to Ceftiofur, an antibiotic not available in the region. These data indicate that humans and apes interacting in the wild can share genetically and phenotypically similar gastrointestinal bacteria, presumably originating from common environmental sources. Strategies to limit transmission of pathogens between humans and primates, whether that transmission is direct or indirect, would benefit both human health and primate conservation.     

Selenium and sulfur in a greenland ice sheet: relation to fossil fuel combustion

In the combustion of fossil fuels, selenium is mobilized in the atmosphere to a much lesser extent than is sulfur. This difference is ascribed to the chemical behavior of their respective tetravalent oxides. The ratio of selenium to sulfur in glacial ice is characteristic of terrestrial matter, and these elements may find their way to ice sheets by the formation of volatile compounds in biochemical processes.     

Rapid axonal transport of sulfated mucopolysaccharide proteins

When sulfur-35-labeled sodium sulfate is injected intraocularly in the goldfish, labeled sulfated mucopolysaccharides rapidly appear in the contra-lateral optic tectum of the brain, demonstrating the axonal flow of sulfated mucopolysaccharides. The transport rate is the same as that observed for proteins labeled after intraocular injection of tritiated proline. Treatment of the sulfur-35-labeled material with precipitants and enzymes reveals the presence of substances with properties similar to those of heparan sulfate (the major component) and chondroitin sulfate. Dermatan sulfate was not detected.     

Radioimmunoassay for human procollagen

Rabbit antiserums were produced against the procollagen molecule secreted into the medium of cultured human skin fibroblasts. The isolated antigenic, amino terminal portion of the procollagen molecule was purified, labeled with iodine-125, and used in a radioimmunoassay which detected nanogram quantities of the same antigen. With the assay, immunologically identical molecules were detected in the culture mediumn of different strains of human fibroblasts and in normal human serums. Serumns from human cord blood contained a 12-fold higher concentration of the antigen than serums from adults, while serums other vertebrates gave reactions to incomplete cross-reactivity or non-reactivity.     

The DNA binding arm of lambda repressor: critical contacts from a flexible region.

Segments of protein that do not adopt a well-ordered conformation in the absence of DNA can still contribute to site-specific recognition of DNA. The first six residues (NH2-Ser1-Thr2-Lys3-Lys4-Lys5-Pro6-) of phage lambda repressor are flexible but are important for site-specific binding. Low-temperature x-ray crystallography and codondirected saturation mutagenesis were used to study the role of this segment. All of the functional sequences have the form [X]1-[X]2-[Lys or Arg]3-[Lys]4-[Lys or Arg]5-[X]6. A high-resolution (1.8 angstrom) crystal structure shows that Lys3 and Lys4 each make multiple hydrogen bonds with guanines and that Lys5 interacts with the phosphate backbone. The symmetry of the complex breaks down near the center of the site, and these results suggest a revision in the traditional alignment of the six lambda operator sites.     

The Self-Assembly Mechanism of Alkanethiols on Au(111)

The self-assembly mechanism of alkanethiol monolayers on the (111) surface of gold was discovered with the use of an ultrahigh-vacuum scanning tunneling microscope. Monolayer formation follows a two-step process that begins with condensation of low-density crystalline islands, characterized by surface-aligned molecular axes, from a lower density lattice-gas phase. At saturation coverage of this phase, the monolayer undergoes a phase transition to a denser phase by realignment of the molecular axes with the surface normal. These studies reveal the important role of molecule-substrate and molecule-molecule interactions in the self-assembly of these technologically important material systems.     

Global mapping of the yeast genetic interaction network

A genetic interaction network containing approximately 1000 genes and approximately 4000 interactions was mapped by crossing mutations in 132 different query genes into a set of approximately 4700 viable gene yeast deletion mutants and scoring the double mutant progeny for fitness defects. Network connectivity was predictive of function because interactions often occurred among functionally related genes, and similar patterns of interactions tended to identify components of the same pathway. The genetic network exhibited dense local neighborhoods; therefore, the position of a gene on a partially mapped network is predictive of other genetic interactions. Because digenic interactions are common in yeast, similar networks may underlie the complex genetics associated with inherited phenotypes in other organisms.