Homologous recombination within subtelomeric repeat sequences generates chromosome size polymorphisms in P. falciparum

We present restriction maps for chromosomes 1 and 2 of six cloned lines of P. falciparum. These delineate the locations of eight genetic markers, including genes for five antigens. In parasites from diverse areas, chromosome structure is conserved in central regions but is polymorphic both in length and sequence near the telomeres. The telomeres and adjacent sequences comprise a conserved structure at the ends of most P. falciparum chromosomes. However, the subtelomeric zones are polymorphic and coincide with the locations of a repetitive element (rep20). Deletions of rep20 generate clones of P. falciparum that lack rep20 on one or both ends of chromosomes 1 or 2, and larger deletions remove telomere-proximal genes as well. The chromosome length polymorphisms can therefore be largely explained by recombination within these blocks of repeats, a mechanism that is also important in the generation of diversity in genes for repetitive antigens of P. falciparum.     

Genomic Investigation into Strain Heterogeneity and Pathogenic Potential of the Emerging Gastrointestinal Pathogen Campylobacter ureolyticus

The recent detection and isolation of C. ureolyticus from patients with diarrhoeal illness and inflammatory bowel diseases warrants further investigation into its role as an emerging pathogen of the human gastrointestinal tract. Regarding the pathogenic mechanisms employed by this species we provide the first whole genome analysis of two C. ureolyticus isolates including the type strain. Comparative analysis, subtractive hybridisation and gene ontology searches against other Campylobacter species identifies the high degree of heterogenicity between C. ureolyticus isolates, in addition to the identification of 106 putative virulence associated factors, 52 of which are predicted to be secreted. Such factors encompass each of the known virulence tactics of pathogenic Campylobacter spp. including adhesion and colonisation (CadF, PEB1, IcmF and FlpA), invasion (ciaB and 16 virB-virD4 genes) and toxin production (S-layer RTX and ZOT). Herein, we provide the first virulence catalogue for C. ureolyticus, the components of which theoretically provide this emerging species with sufficient arsenal to establish pathology.     

814. VARRONIA RUPICOLA

Varronia rupicola (Urb.) Britton (Boraginaceae) a Critically Endangered shrub, restricted to three Caribbean islands – Puerto Rico, Vieques and Anegada—is described and illustrated. Its conservation status and distribution are reviewed.     

Early inhibition of the Na+/K+-ATPase ion pump during acetaminophen-induced hepatotoxicity in rat

The status of Na+ regulation was examined during early stages of alkylation insult to rat liver. Na+/K+-ATPase activity in plasma membranes declined by 52% within 3 hr of treatment with 850 mg/kg acetaminophen. This loss preceded the release of alanine aminotransferase (2880 +/- 1550 U/ml) and necrosis (2+) seen at 24 hr. Activities of 5'-nucleotidase and Mg2+-ATPase and recovery of plasma membranes were comparatively unchanged at 3 hr. Because damage to Na+/K+-ATPase appeared early in the pathogenesis of acetaminophen hepatotoxicity, loss of hepatocellular Na+ regulation could represent one of the critical molecular consequences of lethal alkylation by acetaminophen.     

Validated predictive modelling of the environmental resistome

Multi-drug-resistant bacteria pose a significant threat to public health. The role of the environment in the overall rise in antibiotic-resistant infections and risk to humans is largely unknown. This study aimed to evaluate drivers of antibiotic-resistance levels across the River Thames catchment, model key biotic, spatial and chemical variables and produce predictive models for future risk assessment. Sediment samples from 13 sites across the River Thames basin were taken at four time points across 2011 and 2012. Samples were analysed for class 1 integron prevalence and enumeration of third-generation cephalosporin-resistant bacteria. Class 1 integron prevalence was validated as a molecular marker of antibiotic resistance; levels of resistance showed significant geospatial and temporal variation. The main explanatory variables of resistance levels at each sample site were the number, proximity, size and type of surrounding wastewater-treatment plants. Model 1 revealed treatment plants accounted for 49.5% of the variance in resistance levels. Other contributing factors were extent of different surrounding land cover types (for example, Neutral Grassland), temporal patterns and prior rainfall; when modelling all variables the resulting model (Model 2) could explain 82.9% of variations in resistance levels in the whole catchment. Chemical analyses correlated with key indicators of treatment plant effluent and a model (Model 3) was generated based on water quality parameters (contaminant and macro- and micro-nutrient levels). Model 2 was beta tested on independent sites and explained over 78% of the variation in integron prevalence showing a significant predictive ability. We believe all models in this study are highly useful tools for informing and prioritising mitigation strategies to reduce the environmental resistome.