Molecular Epidemiology of Carbapenem Non-Susceptible Acinetobacter baumannii in France

Carbapenem-resistant Acinetobacter baumannii have emerged globally. The objective of this study was to investigate the epidemiology, clonal diversity and resistance mechanisms of imipenem non-susceptible A. baumannii isolates in France. Between December 2010 and August 2011, 132 notifications were collected, including 37 outbreaks corresponding to 242 cases (2 to 55 per cluster). Multilocus sequence typing, pulsed-field gel electrophoresis (PFGE) and characterisation of carbapenemase-encoding genes were performed on 110 non-repetitive isolates. Gene bla _OXA-23 was the most frequently detected (82%), followed by bla _OXA-24 (11%) and bla _OXA-58 (7%). Eleven sequence types (ST) were distinguished, among which sequence types ST1, ST2 (64%), ST20, ST25, ST85 and ST107. Isolates from epidemiological clusters had the same ST and resistance genes, indicating probable transmission within centres. In contrast, PFGE types of isolates differed among centres, arguing against transmission among centers. This study provides the first epidemiological snapshot of the population of A. baumannii with reduced susceptibility to carbapenems from France, and further underlines the predominance of international clones.     

Vicariance and endemism in a Neotropical savanna hotspot: distribution patterns of Cerrado squamate reptiles

Aim To test predictions of the vicariance model, to define basic biogeographical units for Cerrado squamates, and to discuss previous biogeographical hypotheses. Location Cerrado; South American savannas south of the Amazon, extending across central Brazil, with marginal areas in Bolivia and Paraguay and isolated relictual enclaves in adjacent regions. Methods We compiled species occurrence records via field sampling and revision of museum specimens and taxonomic literature. All species were mapped according to georeferenced locality records, and classified as (1) endemic or non‐endemic, (2) typical of plateaus or depressions, and (3) typical of open or forested habitats. We tested predictions of the vicariance model using biotic element analysis, searching for non‐random clusters of species ranges. Spatial congruence of biotic elements was compared with putative areas of endemism revealed by sympatric restricted‐range species. Effects of topographical and vegetational mosaics on distribution patterns were studied according to species composition in biotic elements and areas of endemism. Results We recorded 267 Cerrado squamates, of which 103 (39%) are endemics, including 20 amphisbaenians (61% endemism), 32 lizards (42%) and 51 snakes (32%). Distribution patterns corroborated predictions of the vicariance model, revealing groups of species with significantly clustered ranges. An analysis of endemic species recovered seven biotic elements, corroborating results including non‐endemics. Sympatric restricted‐range taxa delimited 10 putative areas of endemism, largely coincident with core areas of biotic elements detected with endemic taxa. Distribution patterns were associated with major topographical and vegetational divisions of the Cerrado. Endemism prevailed in open, elevated plateaus, whereas faunal interchange, mostly associated with forest habitats, was more common in peripheral depressions. Main conclusions Our results indicate that vicariant speciation has strongly shaped Cerrado squamate diversity, in contrast to earlier studies emphasizing faunal interchange and low endemism in the Cerrado vertebrate fauna. Levels of squamate endemism are higher than in any other Cerrado vertebrate group. The high number of recovered endemics revealed previously undetected areas of evolutionary relevance, indicating that biogeographical patterns in the Cerrado were poorly represented in previous analyses. Although still largely undocumented, effects of vicariant speciation may be prevalent in a large fraction of Cerrado and Neotropical biodiversity.     

YAP regulates periodontal ligament cell differentiation into myofibroblast interacted with RhoA/ROCK pathway

During orthodontic tooth movement (OTM), periodontal ligament cells (PDLCs) receive the mechanical stimuli and transform it into myofibroblasts (Mfbs). Indeed, previous studies have demonstrated that mechanical stimuli can promote the expression of Mfb marker α-smooth muscle actin (α-SMA) in PDLCs. Transforming growth factor β1 (TGF-β1), as the target gene of yes-associated protein (YAP), has been proven to be involved in this process. Here, we sought to assess the role of YAP in Mfbs differentiation from PDLCs. The time-course expression of YAP and α-SMA was manifested in OTM model in vivo as well as under tensional stimuli in vitro. Inhibition of RhoA/Rho-associated kinase (ROCK) pathway using Y27632 significantly reduced tension-induced Mfb differentiation and YAP expression. Moreover, overexpression of YAP with lentiviral transfection in PDLCs rescued the repression effect of Mfb differentiation induced by Y27632. These data together suggest a crucial role of YAP in regulating tension-induced Mfb differentiation from PDLC interacted with RhoA/ROCK pathway.     

Effects of hydrogen peroxide on the content of major volatile halogenated compounds in the red alga <Emphasis Type="Italic">Asparagopsis taxiformis</Emphasis> (Bonnemaisoniaceae)

The genus Asparagopsis is a prolific source of halogenated metabolites. Due to its commercial applications, it has been intensively cultivated in southern Portugal. In the present study, we assess if the internal levels of the major halogenated metabolites (bromoform and dibromoacetic acid) in Asparagopsis taxiformis can be increased with hydrogen peroxide (H₂O₂) addition. Previous studies with red algae showed that the production/release of bromoform can be enhanced by exogenously supplying H₂O₂. However, no study has assessed if H₂O₂ supply enhances the content of secondary metabolites within the biomass. This detail is important as the objective of the proposed research is to enhance the content of these valuable metabolites in the produced biomass. Both the activity of the haloperoxidase enzyme and the metabolite content were assessed on short-term and long-term incubation periods to H₂O₂. To determine the susceptibility of A. taxiformis photosynthetic performance to the imposed oxidative stress, the in vivo fluorescence of photosystem II was monitored. A. taxiformis was shown to be physiologically vulnerable to H₂O₂, given the observed decrease of the maximum quantum yield of photosynthesis (F _v/F _m). Contrary to what was expected, the presence of H₂O₂ inhibited the activity of the iodoperoxidase enzyme. Nevertheless, the extracted halogenated metabolites were higher over the first hours of exposure to H₂O₂, decreasing after 48 h. These results are probably related to the prosthetic group of the halogenated enzyme in A. taxiformis and the long-term oxidative stress damage of H₂O₂ exposure. Considering the objective of the proposed research, addition of H₂O₂ to the cultures, prior (3 h) to biomass harvesting, increases the metabolite content.     

Adaptive Admixture of HLA Class I Allotypes Enhanced Genetically Determined Strength of Natural Killer Cells in East Asians

Human natural killer (NK) cells are essential for controlling infection, cancer, and fetal development. NK cell functions are modulated by interactions between polymorphic inhibitory killer cell immunoglobulin-like receptors (KIR) and polymorphic HLA-A, -B, and -C ligands expressed on tissue cells. All HLA-C alleles encode a KIR ligand and contribute to reproduction and immunity. In contrast, only some HLA-A and -B alleles encode KIR ligands and they focus on immunity. By high-resolution analysis of KIR and HLA-A, -B, and -C genes, we show that the Chinese Southern Han (CHS) are significantly enriched for interactions between inhibitory KIR and HLA-A and -B. This enrichment has had substantial input through population admixture with neighboring populations, who contributed HLA class I haplotypes expressing the KIR ligands B*46:01 and B*58:01, which subsequently rose to high frequency by natural selection. Consequently, over 80% of Southern Han HLA haplotypes encode more than one KIR ligand. Complementing the high number of KIR ligands, the CHS KIR locus combines a high frequency of genes expressing potent inhibitory KIR, with a low frequency of those expressing activating KIR. The Southern Han centromeric KIR region encodes strong, conserved, inhibitory HLA-C-specific receptors, and the telomeric region provides a high number and diversity of inhibitory HLA-A and -B-specific receptors. In all these characteristics, the CHS represent other East Asians, whose NK cell repertoires are thus enhanced in quantity, diversity, and effector strength, likely augmenting resistance to endemic viral infections.     

Body mass and behavior in Swiss mice subjected to continuous or discontinuous food restriction and refeeding

Food restriction (FR) is hypothesized to decrease body fat content of an animal and thus prevent obesity. However, the response of energy budget to a continuous (CFR) or discontinuous FR (DFR) remains inconsistent. In the present study, effects of CFR or DFR and refeeding on energy budget and behavior were examined in male Swiss mice. CFR significantly decreased the energy expenditure associated with basal metabolic rate (BMR) and activity behavior, but not sufficiently to compensate for energy deficit and thus resulted in lower body mass and fat content. DFR mice had a significantly higher food intake on ad libitum days and showed increases in BMR and activity after 4 weeks’ DFR, which might resulted in lower body mass and less body fat than controls. After being refed ad libitum, both CFR and DFR mice had similar body mass, BMR, and behavioral patterns to controls but had 95% and 75% higher fat content. This suggested that not only CFR but also DFR would be a significant factor in the process of obesity for animals that were refed ad libitum. It also indicated that food restriction interrupted many times by periods of ad libitum feeding had the same long-term effects like continuous underfeeding.     

Is embryo abortion a post‐zygotic barrier to gene flow between Littorina ecotypes?

Genetic incompatibilities contribute to reproductive isolation between many diverging populations, but it is still unclear to what extent they play a role if divergence happens with gene flow. In contact zones between the "Crab" and "Wave" ecotypes of the snail Littorina saxatilis, divergent selection forms strong barriers to gene flow, while the role of post‐zygotic barriers due to selection against hybrids remains unclear. High embryo abortion rates in this species could indicate the presence of such barriers. Post‐zygotic barriers might include genetic incompatibilities (e.g. Dobzhansky–Muller incompatibilities) but also maladaptation, both expected to be most pronounced in contact zones. In addition, embryo abortion might reflect physiological stress on females and embryos independent of any genetic stress. We examined all embryos of >500 females sampled outside and inside contact zones of three populations in Sweden. Females' clutch size ranged from 0 to 1,011 embryos (mean 130 ± 123), and abortion rates varied between 0% and 100% (mean 12%). We described female genotypes by using a hybrid index based on hundreds of SNPs differentiated between ecotypes with which we characterized female genotypes. We also calculated female SNP heterozygosity and inversion karyotype. Clutch size did not vary with female hybrid index, and abortion rates were only weakly related to hybrid index in two sites but not at all in a third site. No additional variation in abortion rate was explained by female SNP heterozygosity, but increased female inversion heterozygosity added slightly to increased abortion. Our results show only weak and probably biologically insignificant post‐zygotic barriers contributing to ecotype divergence, and the high and variable abortion rates were marginally, if at all, explained by hybrid index of females.