VIM‐1 carbapenemase‐producing Escherichia coli in gulls from southern France

Acquired carbapenemases currently pose one of the most worrying public health threats related to antimicrobial resistance. A NDM‐1‐producing Salmonella Corvallis was reported in 2013 in a wild raptor. Further research was needed to understand the role of wild birds in the transmission of bacteria resistant to carbapenems. Our aim was to investigate the presence of carbapenem‐resistant Escherichia coli in gulls from southern France. In 2012, we collected 158 cloacal swabs samples from two gull species: yellow‐legged gulls (Larus michahellis) that live in close contact with humans and slender‐billed gulls (Chroicocephalus genei) that feed at sea. We molecularly compared the carbapenem‐resistant bacteria we isolated through culture on selective media with the carbapenem‐susceptible strains sampled from both gull species and from stool samples of humans hospitalized in the study area. The genes coding for carbapenemases were tested by multiplex PCR. We isolated 22 carbapenem‐resistant E. coli strains from yellow‐legged gulls while none were isolated from slender‐billed gulls. All carbapenem‐resistant isolates were positive for bla_VIM‐1 gene. VIM‐1‐producing E. coli were closely related to carbapenem‐susceptible strains isolated from the two gull species but also to human strains. Our results are alarming enough to make it urgently necessary to determine the contamination source of the bacteria we identified. More generally, our work highlights the need to develop more bridges between studies focusing on wildlife and humans in order to improve our knowledge of resistant bacteria transmission routes.     

THE ORIGIN OF WEST EUROPEAN SUBSPECIES OF HONEYBEES (APIS MELLIFERA): NEW INSIGHTS FROM MICROSATELLITE AND MITOCHONDRIAL DATA

Apis mellifera is composed of three evolutionary branches including mainly African (branch A), western and northern European (branch M), and southeastern European (branch C) populations. The existence of morphological clines extending from the equator to the Polar Circle through Morocco and Spain raised the hypothesis that the branch M originated in Africa. Mitochondrial DNA analysis revealed that branches A and M were characterized by highly diverged lineages implying very remote links between both branches. It also revealed that mtDNA haplotypes from lineages A coexisted with haplotypes M in the Iberian Peninsula and formed a south-north frequency cline, suggesting that this area could be a secondary contact zone between the two branches. By analyzing 11 populations sampled along a France-Spain/Portugal-Morocco-Guinea transect at 8 microsatellite loci and the DraI RFLP of the COI-COII mtDNA marker, we show that Iberian populations do not present any trace of “africanization” and are very similar to French populations when considering microsatellite markers. Therefore, the Iberian Peninsula is not a transition area. The higher haplotype A variability observed in Spanish and Portuguese samples compared to that found in Africa is explained by a higher mutation rate and multiple and recent introductions. Selection appears to be the best explanation to the morphological and allozymic clines and to the diffusion and maintenance of African haplotypes in Spain and Portugal.     

Expression of GABA Receptor ρ Subunits in Rat Brain

Abstract: The GABA receptor ρ1, ρ2, and ρ3 subunits are expressed in the retina where they form bicuculline-insensitive GABA_C receptors. We used northern blot, in situ hybridization, and RT-PCR analysis to study the expression of ρ subunits in rat brains. In situ hybridization allowed us to detect ρ-subunit expression in the superficial gray layer of the superior colliculus and in the cerebellar Purkinje cells. RT-PCR experiments indicated that (a) in retina and in domains that may contain functional GABA_C receptors, ρ2 and ρ1 subunits are expressed at similar levels; and (b) in domains and in tissues that are unlikely to contain GABA_C receptors, ρ2 mRNA is enriched relative to ρ1 mRNA. These results suggest that both ρ1 and ρ2 subunits are necessary to form a functional GABA_C receptor. The use of RT-PCR also showed that, except in the superior colliculus, ρ3 is expressed along with ρ1 and ρ2 subunits. We also raised an antibody against a peptide sequence unique to the ρ1 subunit. The use of this antibody on cerebellum revealed the rat ρ1 subunit in the soma and dendrites of Purkinje neurons. The allocation of GABA_C receptor subunits to identified neurons paves the way for future electrophysiological studies.     

G-quadruplexes in helminth parasites

Parasitic helminths infecting humans are highly prevalent infecting ∼2 billion people worldwide, causing inflammatory responses, malnutrition and anemia that are the primary cause of morbidity. In addition, helminth infections of cattle have a significant economic impact on livestock production, milk yield and fertility. The etiological agents of helminth infections are mainly Nematodes (roundworms) and Platyhelminths (flatworms). G-quadruplexes (G4) are unusual nucleic acid structures formed by G-rich sequences that can be recognized by specific G4 ligands. Here we used the G4Hunter Web Tool to identify and compare potential G4 sequences (PQS) in the nuclear and mitochondrial genomes of various helminths to identify G4 ligand targets. PQS are nonrandomly distributed in these genomes and often located in the proximity of genes. Unexpectedly, a Nematode, Ascaris lumbricoides, was found to be highly enriched in stable PQS. This species can tolerate high-stability G4 structures, which are not counter selected at all, in stark contrast to most other species. We experimentally confirmed G4 formation for sequences found in four different parasitic helminths. Small molecules able to selectively recognize G4 were found to bind to Schistosoma mansoni G4 motifs. Two of these ligands demonstrated potent activity both against larval and adult stages of this parasite.     

Cre-mediated recombination in the skin melanocyte lineage

Organ-specific expression of a Cre recombinase allows the analysis of gene function in a particular tissue or cell type. Using a 6.1 kb promoter from the mouse tyrosinase gene, we generated and characterized two lines of transgenic mice that express Cre recombinase in melanoblasts. Utilizing a Cre-responsive reporter mouse strain, genetic recombination was detected in the melanoblasts of the skin from embryonic day 11.5. In addition, Cre-expression was detected in the skin and eyes of mice. Cre transgene activity was occasionally detected in the brain and peripheral nerves but not in other tissues. When Tyr::Cre mice were crossed with mice carrying a homozygous loxP conditional mutation for the insulin-like growth factor receptor gene (Igf1r), Cre-melanoblast-specific recombination pattern was confirmed and no abnormal phenotype was observed. In conclusion, Tyr::Cre transgenic mice provide a valuable tool to follow the cell lineage and to examine gene function in melanocyte development and transformation.     

Does placenta position modify the risk of placental abruption in car crashes?

The goal of this paper is to study the influence of placenta position on the risk of placenta abruption following a car crash involving a full term pregnant woman in the driver's seat. We developed an anatomically precise finite element numerical model of a pregnant woman. This numerical model was validated using experimental data from crash tests using cadavers given to science. For a frontal impact at a speed of 20 km/h, the mean value of peak strain levels at the utero-placenta interface were found to be close to 20%, independent of placenta position, representing an adverse foetal outcome risk of approximately 15%. This study found no significant effect of placenta position on the risk of placenta abruption. Our anatomically precise approach does however confirm the interest of using a numerical model when studying injury mechanisms in pregnant women involved in car crashes.     

Functional impairment of MSC induced by transient warming events: Correlation with loss of adhesion and altered cell size

Background

We recently showed that transient warming effects decreased the functional and adhesion properties of mesenchymal stromal cells (MSC) while post-thaw viability remained high. In an attempt to better predict functional impairment of cryopreserved MSC, we further analysed the correlation between viability, immunosuppressive activity and adhesion of cells exposed or not to warming events.

Characterization of apoptosis signal transduction pathways in HL-5 cardiomyocytes exposed to ischemia/reperfusion oxidative stress model

During ischemia/reperfusion (I/R), cardiomyocytes are exposed to sudden lack of nutrients and successively to radical oxygen species (ROS). In the present study, we used the HL-5 cardiac atrial myocyte cell line exposed to serum/glucose depletion added or not in H(2)O(2) to mimic ROS during ischemia, then replaced in their standard culture medium to simulate reperfusion. We investigated the effects of serum/glucose depletion combined or not to ROS exposure on AKT and MAP kinases activation to address the role of each event with respect to apoptosis. We demonstrate that serum/glucose depletion per se did not induce apoptosis when compared to ROS exposure. In particular, ROS recruited p38MAPK and JNK pathways. SB202190 preventing p38MAPK activity, partially protected HL-5 from apoptosis while blocking JNK, thanks to JNKI, further enhanced apoptosis. Blocking phosphatidylinositol (PI) 3-kinase with LY294002 or ERKs with U0126 was without consequence on apoptosis. Finally, BCL-2 and BCL-X(L/S) expression levels were analyzed in cells exposed to 1 h ischemia followed by 12-h reperfusion in the presence or not of SB202190; BCL-2, but not BCL-X(L/S), expression was decreased in ROS treated cells but SB202190 failed to restore BCL-2 level. Our data suggest that p38MAPK activation primarily mediates ROS-induced apoptosis while concomitant JNK activation would represent a scavenger pathway for cells trying to escape apoptosis.     

CD36 inhibitors reduce postprandial hypertriglyceridemia and protect against diabetic dyslipidemia and atherosclerosis

CD36 is recognized as a lipid and fatty acid receptor and plays an important role in the metabolic syndrome and associated cardiac events. The pleiotropic activity and the multiple molecular associations of this scavenger receptor with membrane associated molecules in different cells and tissues have however questioned its potential as a therapeutic target. The present study shows that it is possible to identify low molecular weight chemicals that can block the CD36 binding and uptake functions. These inhibitors were able to reduce arterial lipid deposition, fatty acid intestinal transit, plasma concentration of triglycerides and glucose, to improve insulin sensitivity, glucose tolerance and to reduce the plasma concentration of HbAc1 in different and independent rodent models. Correlation between the anti-CD36 activity of these inhibitors and the known pathophysiological activity of this scavenger receptor in the development of atherosclerosis and diabetes were observed at pharmacological doses. Thus, CD36 might represent an attractive therapeutic target.