High Prevalence of Vancomycin-Resistant Enterococci in Swedish Sewage

In Europe the use of the growth promoter avoparcin is considered to have selected for vancomycin-resistant enterococci (VRE). Sweden ceased using avoparcin in 1986, and only occasional cases of VRE from hospitals have been reported since 1995. Within the framework of a European study, samples from urban raw sewage, treated sewage, surface water, and hospital sewage in Sweden (n = 118) were screened for VRE. Surprisingly, VRE were isolated from 21 of 35 untreated sewage samples (60%), from 5 of 14 hospital sewage samples (36%), from 6 of 32 treated sewage samples (19%), and from 1 of 37 surface water samples. Thirty-five isolates from 33 samples were further characterized by geno- and phenotyping, MIC determination, and PCR analysis. Most isolates (30 of 35) carried the vanA gene, and the majority (24 of 35) of the isolates were Enterococcus faecium. Most of the VRE were multiresistant. The typing revealed high diversity of the isolates. However, one major cluster with seven identical or similar isolates was found. These isolates came from three different sewage treatment plants and were collected at different occasions during 1 year. All VRE from hospital sewage originated from one of the two hospitals studied. That hospital also had vancomycin consumption that was 10-fold that of the other. We conclude that VRE were commonly found in sewage samples in Sweden. The origin might be both healthy individuals and individuals in hospitals. Possibly, antimicrobial drugs or chemicals released into the sewage system may sustain VRE in the system.     

Observation of correlated X-ray scattering at atomic resolution

Tools to study disordered systems with local structural order, such as proteins in solution, remain limited. Such understanding is essential for e.g. rational drug design. Correlated X-ray scattering (CXS) has recently attracted new interest as a way to leverage next-generation light sources to study such disordered matter. The CXS experiment measures angular correlations of the intensity caused by the scattering of X-rays from an ensemble of identical particles, with disordered orientation and position. Averaging over 15 496 snapshot images obtained by exposing a sample of silver nanoparticles in solution to a micro-focused synchrotron radiation beam, we report on experimental efforts to obtain CXS signal from an ensemble in three dimensions. A correlation function was measured at wide angles corresponding to atomic resolution that matches theoretical predictions. These preliminary results suggest that other CXS experiments on disordered ensembles—such as proteins in solution—may be feasible in the future.     

A Genetic Predictive Model for Canine Hip Dysplasia: Integration of Genome Wide Association Study (GWAS) and Candidate Gene Approaches

Canine hip dysplasia is one of the most prevalent developmental orthopedic diseases in dogs worldwide. Unfortunately, the success of eradication programs against this disease based on radiographic diagnosis is low. Adding the use of diagnostic genetic tools to the current phenotype-based approach might be beneficial. The aim of this study was to develop a genetic prognostic test for early diagnosis of hip dysplasia in Labrador Retrievers. To develop our DNA test, 775 Labrador Retrievers were recruited. For each dog, a blood sample and a ventrodorsal hip radiograph were taken. Dogs were divided into two groups according to their FCI hip score: control (A/B) and case (D/E). C dogs were not included in the sample. Genetic characterization combining a GWAS and a candidate gene strategy using SNPs allowed a case-control population association study. A mathematical model which included 7 SNPs was developed using logistic regression. The model showed a good accuracy (Area under the ROC curve = 0.85) and was validated in an independent population of 114 dogs. This prognostic genetic test represents a useful tool for choosing the most appropriate therapeutic approach once genetic predisposition to hip dysplasia is known. Therefore, it allows a more individualized management of the disease. It is also applicable during genetic selection processes, since breeders can benefit from the information given by this test as soon as a blood sample can be collected, and act accordingly. In the authors’ opinion, a shift towards genomic screening might importantly contribute to reducing canine hip dysplasia in the future. In conclusion, based on genetic and radiographic information from Labrador Retrievers with hip dysplasia, we developed an accurate predictive genetic test for early diagnosis of hip dysplasia in Labrador Retrievers. However, further research is warranted in order to evaluate the validity of this genetic test in other dog breeds.     

Cannabinoid receptor interactions with the antagonists SR 141716A and SR 144528.

The G protein-coupled cannabinoid receptor subtypes CB1 and CB2 have been cloned from several species. The CB1 receptor is highly conserved across species, whereas the CB2 receptor shows considerable cross-species variations. The two human receptors share only 44% overall identity, ranging from 35% to 82% in the transmembrane regions. Despite this structural disparity, the most potent cannabinoid agonists currently available are largely undiscriminating and are therefore unsatisfactory tools for investigating the architecture of ligand binding sites. However, the availability of two highly specific antagonists, SR 141716A for the CB1 receptor and SR 144528 for the CB2 receptor, has allowed us to adopt a systematic approach to defining their respective binding sites through the use of chimeric CB1 receptor/CB2 receptor constructs, coupled with site-directed mutagenesis. We identified the region encompassed by the fourth and fifth transmembrane helices as being critical for antagonist specificity. Both the wild type human receptors overexpressed in heterologous systems are autoactivated; SR 141716A and SR 144528 exhibit classical inverse agonist properties with their respective target receptors. In addition, through its interaction with the CB1 receptor SR 141716A blocks the Gi protein-mediated activation of mitogen-activated protein kinase stimulated by insulin or insulin-like growth factor I. An in-depth analysis of this discovery has led to a modified three-state model for the CB1 receptor, one of which implicates the SR 141716A-mediated sequestration of Gi proteins, with the result that the growth factor-stimulated intracellular pathways are effectively impeded.     

Genotype versus phenotype in the circumscription of bacterial species: the case of Pseudomonas stutzeri and Pseudomonas chloritidismutans

The phenotypic characteristic of strain AW-1(T) of Pseudomonas chloritidismutans that is most relevant from the taxonomic point of view appears to be the capacity of growth under anaerobic conditions using chlorate as electron acceptor. This property is not restricted to this species only within the genus Pseudomonas, since it is also present in strains of genomovars 1 or 5, and 3 of Pseudomonas stutzeri. P. chloritidismutans has been described as a non-denitrifying species, but the isolation of variants that are able to grow anaerobically in the presence of nitrate is possible after subcultivation under selective conditions. The subdivision of P. stutzeri into a number of species on the basis of these characteristics does not help to clarify the phylogenetic relationships among the members of an otherwise coherent group of strains, and the considerations presented in this communication support the reclassification of the new species name P. chloritidismutans, which in our opinion, should be considered as a Junior name of P. stutzeri. A multilocus sequence analysis, together with a phenotypic analysis of the anaerobic oxidative metabolism, gives new insights into the phylogeny and evolution of the species.     

Evidence of maternal QTL affecting growth and obesity in adult mice

Most quantitative trait loci (QTL) studies fail to account for the effect that the maternal genotype may have on an individual’s phenotypes, even though maternal effect QTL have been shown to account for considerable variation in growth and obesity traits in mouse models. Moreover, the fetal programming theory suggests that maternal effects influence an offspring’s adult fitness, although the genetic nature of fetal programming remains unclear. Within this context, our study focused on mapping genomic regions associated with maternal effect QTL by analyzing the phenotypes of chromosomes 2 and 7 subcongenic mice from genetically distinct dams. We analyzed 12 chromosome 2 subcongenic strains that spanned from 70 to 180 Mb with CAST/EiJ donor regions on the background of C57BL/6 J, and 14 chromosome 7 subcongenic strains that spanned from 81 to 111 Mb with BALB/cByJ donor regions on C57BL/6ByJ background. Maternal QTL analyses were performed on the basis of overlapping donor regions between subcongenic strains. We identified several highly significant (P < 5 × 10⁻⁴) maternal QTL influencing total body weight, organ weight, and fat pad weights in both sets of subcongenics. These QTL accounted for 1.9-11.7% of the phenotypic variance for growth and obesity and greatly narrowed the genomic regions associated with the maternal genetic effects. These maternal effect QTL controlled phenotypic traits in adult mice, suggesting that maternal influences at early stages of development may permanently affect offspring performance. Identification of maternal effects in our survey of two sets of subcongenic strains, representing approximately 5% of the mouse genome, supports the hypothesis that maternal effects represent significant sources of genetic variation that are largely ignored in genetic studies.     

Natural variation of photosynthetic efficiency in Arabidopsis thaliana accessions under low temperature conditions

Low, but non-freezing, temperatures have negative effects on plant growth and development. Despite some molecular signalling pathways being known, the mechanisms causing different responses among genotypes are still poorly understood. Photosynthesis is one of the processes that are affected by low temperatures. Using an automated phenotyping platform for chlorophyll fluorescence imaging the steady state quantum yield of photosystem II (PSII) electron transport (Φ_PSII) was measured and used to quantify the effect of moderately low temperature on a population of Arabidopsis thaliana natural accessions. Observations were made over the course of several weeks in standard and low temperature conditions and a strong decrease in Φ_PSII upon the cold treatment was found. A genome wide association study identified several quantitative trait loci (QTLs) that are associated with changes in Φ_PSII in low temperature. One candidate for a cold specific QTL was validated with a mutant analysis to be one of the genes that is likely involved in the PSII response to the cold treatment. The gene encodes the PSII associated protein PSB27 which has already been implicated in the adaptation to fluctuating light.     

Polyphasic characterization of Pseudomonas stutzeri CLN100 which simultaneously degrades chloro- and methylaromatics: a new genomovar within the species

Strain CLN100 was isolated after enrichment on mineral medium with chloronaphthalene as the only carbon and energy source. It was able to use simultaneously and productively chloro- and methyl-derivatives of naphthalene and salicylate through a chromosomally encoded meta pathway. Phenotypic, chemotaxonomic and genotypic characterization classified strain CLN100 as a member of the species Pseudomonas stutzeri. DNA-DNA hybridizations, 16S rDNA, gyrB, rpoD sequences, and molecular fingerprinting indicate that strain CLN100 is a representative of a new genomovar (genomovar 10) within the species.     

Exploitation of expression profiles: examples in oncology

The analysis of biological processes has been revolutionized by the emergence of the DNA array technology. As cellular biological events are controlled by gene expression, their modulations are markers of the cellular activity. These modulations can be indicative of either a physiological process or a pathological one. Monitoring of the expression levels of thousands of genes simultaneously, the expression profiling method is based upon comparative studies where the identification of the differentially expressed genes in two samples is aimed. The two samples under study may be compared temporally or following drug treatment, they may also originate from different sources, e.g. normal versus pathological samples. In that case, gene expression profiling is conducted for diagnostics purposes or therapy monitoring, and offers an opportunity to identify new drug targets. Using different examples, we describe the potentialities of this approach in oncology.