Prevalence of Type VI Secretion System in Spanish Campylobacter jejuni Isolates

Infections from Campylobacter jejuni pose a serious public health problem and are now considered the leading cause of foodborne bacterial gastroenteritis throughout the world. Sequencing of C. jejuni genomes has previously allowed a number of loci to be identified, which encode virulence factors that aid survival and pathogenicity. Recently, a Type VI secretion system (T6SS) consisting of 13 conserved genes was described in C. jejuni strains and recognised to promote pathogenicity and adaptation to the environment. In this study, we determined the presence of this T6SS in 63 Spanish C. jejuni isolates from the food chain and urban effluents using whole‐genome sequencing. Our findings demonstrated that nine (14%) strains harboured the 13 ORFs found in prototype strain C. jejuni 108. Further studies will be necessary to determine the prevalence and importance of T6SS‐positive C. jejuni strains.     

Mercury in the natural gas industry in Canada

There are an estimated 1,500 natural gas facilities across Canada, most of which used mercury (Hg) in metering equipment at one time or another. Although the use of mercury has ceased, many gas industry buildings still contain detectable levels of Hg in air. Air Hg levels are generally low but indoor remediation is suggested. Worker exposure to the air Hg levels is not considered a significant hazard. Very high soil Hg levels have been observed at numerous sites. Soil Hg levels do not pose an immediate human hazard but are sufficient to be hazardous to ecological receptors. The area of soil contamination, is generally within the buildings or within a few metres of the nearest door. Downward movement of the Hg does not generally extend more than one metre. Remediation of contaminated soil with on-site thermal desorption is recommended as the appropriate soil clean-up technology.     

N-linked glycosylation in Campylobacter jejuni and its functional transfer into E. coli

N-linked protein glycosylation is the most abundant posttranslation modification of secretory proteins in eukaryotes. A wide range of functions are attributed to glycan structures covalently linked to asparagine residues within the asparagine-X-serine/threonine consensus sequence (Asn-Xaa-Ser/Thr). We found an N-linked glycosylation system in the bacterium Campylobacter jejuni and demonstrate that a functional N-linked glycosylation pathway could be transferred into Escherichia coli. Although the bacterial N-glycan differs structurally from its eukaryotic counterparts, the cloning of a universal N-linked glycosylation cassette in E. coli opens up the possibility of engineering permutations of recombinant glycan structures for research and industrial applications.     

剖析肯定陈述强调

本文从词汇、结构、修辞等几方而对英语中经常出现的肯定陈述强调这一语言现象进行了较为全而的阐述，并总结了介入一些英语肯定陈述强调的特点及规律。     

Post-mortem findings in 54 cases of anesthetic associated death in cats from two spay-neuter programs in New York State

Anesthetic-associated death (AAD) in cats is infrequent, but occurs far more frequently than in people. Post-mortem investigations of AAD in cats are uncommon, and results only sporadically published. Here we report the findings in 54 cases of AAD in cats. Significant gross and/or microscopic pre-existing disease, including pulmonary, cardiac, and systemic disease, was detected in 33% of cases. Pulmonary disease was most frequently diagnosed (24% of cases), and included cases of Aelurostrongylus abstrusus infection (9% of cases). Heart disease, including two cases of hypertrophic cardiomyopathy, was less frequent (11% of cases). Four percent died from surgical complications. No?significant gross or microscopic disease was detected in 63% of cases. Additional studies are needed to determine if these findings are representative of AAD in cats in other geographic areas or with access to veterinary care. This study demonstrates that post-mortem investigation of AADs is an important and worthwhile endeavor.     

Facts and fallacies concerning mercury uptake by fish in acid stressed lakes

Concerns about Hg contamination of fish have changed in emphasis from Hg-contaminated systems to more remote and apparently unpolluted systems. For remote lakes, a negative relationship between lake pH and Hg in fish has been demonstrated, implying an effect on Hg uptake from lake acidification. Though this relationship was discussed, and hypotheses put forward concerning the possible mechanisms 8 yr ago, the factors regulating Hg uptake by aquatic biota are still poorly understood. Several recent studies have prompted workers to observe that frequently cited concepts about processes affecting Hg accumulation and cycling are in fact over-simplifications. This review attempts to synthesize and clarify the present state of knowledge. We critically evaluate evidence for a number of controlling factors in the context of the concentrations, the chemical species and the biological uptake processes for Hg. The factors include: trophic status and organic content of water, food chain transfer and biomagnification of Hg, organism age and size effects, feeding strategies, biological and chemical methylation, concentration of cations including H⁺ and Ca²⁺ and the immediate source of Hg.