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Biological invasions can be substantially influenced by the genetic sampling associated with a species' introduction. As a result, we assessed the genetic and evolutionary consequences of the entry and spread of the invasive grass Bromus tectorurn (cheatgrass) across the United States midcontinent through an analysis of 54 populations, using enzyme electrophoresis. On average, these populations display 1.04 alleles per locus (A), 4.1% percent polymorphic loci per population (%P) and an expected mean heterozygosity (Hexp) value of 0.009. Heterozygotes, which have been rarely reported for B. tectorum in North America, occur in three populations in the midcontinent and are likely novel multilocus genotypes that arose postimmigration. The midcontinent distribution of multilocus genotypes suggests that plant immigrants came directly from either the native range or the eastern United States, or both. Continued dispersal of preadapted genotypes and the assembly of populations that are genetic admixtures may enhance this invasion by increasing both the genetic diversity within populations and the selection of novel genotypes arising from occasional outcrossing. The potential for postimmigration evolution in most species points to the largely unrecognized need to block the introduction of new, potentially aggressive genotypes of an alien species already in the United States. [ABSTRACT FROM AUTHOR]

Background. Multidrug-resistant Salmonella enteriea serotype Typhimurium Definitive Type 104 (DT104) emerged in the 1990s and is associated with greater clinical severity than pansusceptible S. Typhimurium. Although infection with DT1O4 is common in the United States, it is rarely associated with outbreaks. From October to December 2003, a cluster of DT104 infections with indistinguishable pulsed-field gel electrophoresis patterns was identified in the northeastern United States. Methods. A case-control study that assessed exposures compared case patients to age- and geography-matched control subjects. Information on consumer purchasing and grocery store suppliers was used to trace the implicated food to its source. Results. We identified 58 case patients in 9 states by pulsed-field gel electrophoresis. Representative isolates were phage type DT104 and were resistant to ampicillin, chloramphenicol, streptomycin, sulfamethoxazole, and tetracycline (R-type ACSSuT). Of 27 patients interviewed for the case-control study, 41% were hospitalized (median duration of hospitalization, 4 days). Compared with 71 healthy control subjects, case patients had more medical comorbidities (matched odds ratio, 4.3; 95% confidence interval, 1.5-12.7). Illness was associated with consuming store-bought ground beef prepared as hamburgers at home (matched odds ratio, 5.3; 95% confidence interval, 1.9-15.3) and with eating raw ground beef (P ⩽ .001). Seven case patients (27%), but no control subjects, ate raw ground beef Product traceback linked cases to a single large ground beef manufacturer previously implicated in a multistate outbreak of highly drug-resistant Salmonella enterica Newport infections in 2002. Conclusions. This first multistate outbreak of highly drug-resistant S. Typhimurium DT104 infection associated with ground beef highlights the need for enhanced animal health surveillance and infection control, prudent use of antimicrobials for animals, improved pathogen reduction during processing, and better product tracking and consumer education. [ABSTRACT FROM AUTHOR]

The article presents a summary of the workshop "Emerging Techniques in Glycobiology," organized by R. Reid Townsend of the University of California at San Francisco in the United States. Key issues discussed include the microanalysis of oligosaccharides that are attached to glycoproteins, the capillary electrophoresis of fluorescent carbohydrate derivatives and approaches to automating the enzymatic structural analysis of glycoprotein-derived glycans and chemical release. The references and equipment used for the workshop are also cited.

The article presents a summary of the workshop "High-Performance Electrophoresis," organized by Lloyd M. Smith of the University of Wisconsin in the United States. Key issues discussed include the performance of capillary array electrophoresis through the use of laser-excited confocal fluorescence detection, high-speed DNA sequencing in ultrathin gels and the use of capillary electrophoresis in the analysis of recombinant proteins. The references and equipment used for the workshop are also cited.