Genotypic and phenotypic traits that distinguish neonatal meningitis-associated Escherichia coli from fecal E. coli isolates of healthy human hosts

Neonatal meningitis Escherichia coli (NMEC) is one of the top causes of neonatal meningitis worldwide. Here, 85 NMEC and 204 fecal E. coli isolates from healthy humans (HFEC) were compared for possession of traits related to virulence, antimicrobial resistance, and plasmid content. This comparison was done to identify traits that typify NMEC and distinguish it from commensal strains to refine the definition of the NMEC subpathotype, identify traits that might contribute to NMEC pathogenesis, and facilitate choices of NMEC strains for future study. A large number of E. coli strains from both groups were untypeable, with the most common serogroups occurring among NMEC being O18, followed by O83, O7, O12, and O1. NMEC strains were more likely than HFEC strains to be assigned to the B2 phylogenetic group. Few NMEC or HFEC strains were resistant to antimicrobials. Genes that best discriminated between NMEC and HFEC strains and that were present in more than 50% of NMEC isolates were mainly from extraintestinal pathogenic E. coli genomic and plasmid pathogenicity islands. Several of these defining traits had not previously been associated with NMEC pathogenesis, are of unknown function, and are plasmid located. Several genes that had been previously associated with NMEC virulence did not dominate among the NMEC isolates. These data suggest that there is much about NMEC virulence that is unknown and that there are pitfalls to studying single NMEC isolates to represent the entire subpathotype.     

HIV-specific CD8+ T cells exhibit markedly reduced levels of Bcl-2 and Bcl-xL

Human immunodeficiency virus-specific CD8(+) T cells are highly sensitive to spontaneous and CD95/Fas-induced apoptosis, and this sensitivity may impair their ability to control HIV infection. To elucidate the mechanism behind this sensitivity, in this study we examined the levels of antiapoptotic molecules Bcl-2 and Bcl-x(L) in HIV-specific CD8(+) T cells from HIV-infected individuals. Bcl-2 expression was markedly decreased in HIV-specific CD8(+) T cells compared with CMV-specific and total CD8(+) T cells from HIV-infected individuals as well as total CD8(+) T cells from healthy donors. CD8(+) T cell Bcl-2 levels inversely correlated with spontaneous and CD95/Fas-induced apoptosis of CD8(+) T cells from HIV-infected individuals. HIV-specific CD8(+) T cells also had significantly lower levels of Bcl-x(L) compared with CMV-specific CD8(+) T cells. Finally, IL-15 induces both Bcl-2 and Bcl-x(L) expression in HIV-specific and total CD8(+) T cells, and this correlated with apoptosis inhibition and increased survival in both short- and long-term cultures. Our data indicate that reduced Bcl-2 and Bcl-x(L) may play an important role in the increased sensitivity to apoptosis of HIV-specific CD8(+) T cells and suggest a possible mechanism by which IL-15 increases their survival.     

CRY2 Is Associated with Depression

Background

Abnormalities in the circadian clockwork often characterize patients with major depressive and bipolar disorders. Circadian clock genes are targets of interest in these patients. CRY2 is a circadian gene that participates in regulation of the evening oscillator. This is of interest in mood disorders where a lack of switch from evening to morning oscillators has been postulated.

Principal Findings

We observed a marked diurnal variation in human CRY2 mRNA levels from peripheral blood mononuclear cells and a significant up-regulation (P = 0.020) following one-night total sleep deprivation, a known antidepressant. In depressed bipolar patients, levels of CRY2 mRNA were decreased (P = 0.029) and a complete lack of increase was observed following sleep deprivation. To investigate a possible genetic contribution, we undertook SNP genotyping of the CRY2 gene in two independent population-based samples from Sweden (118 cases and 1011 controls) and Finland (86 cases and 1096 controls). The CRY2 gene was significantly associated with winter depression in both samples (haplotype analysis in Swedish and Finnish samples: OR = 1.8, P = 0.0059 and OR = 1.8, P = 0.00044, respectively).

Conclusions

We propose that a CRY2 locus is associated with vulnerability for depression, and that mechanisms of action involve dysregulation of CRY2 expression.     

Characterization of Arsenate Uptake by Cultured Primary Rat Astrocytes

Arsenate is known to be accumulated by cultured astrocytes and to stimulate astrocytic glutathione export, but the arsenate uptake into astrocytes has not been characterized so far. To address this topic, we have exposed primary rat astrocyte cultures to arsenate and determined the cellular arsenic content by atomic absorption spectroscopy. Viable astrocytes accumulated arsenate in a time- and concentration-dependent manner. Their cellular arsenic content increased almost proportional with time for up to 60 min after application of arsenate. Analysis of the concentration-dependent increase in the specific arsenic content of the cells after 30 min of arsenate exposure revealed that cultured astrocytes take up arsenate with saturable kinetics by a transport process that has apparent K_M- and V_max-values of 1.7 ± 0.2 mM and 28 ± 4 nmol/(mg protein × 30 min), respectively. Arsenate uptake in viable astrocytes was strongly inhibited by the presence of phosphate or by lowering the incubation temperature to 4 °C and was completely abolished in a sodium ion-free medium. These results strongly suggest that the saturable temperature-dependent arsenate uptake into astrocytes is mediated by a sodium-dependent phosphate cotransporter.     

Emotion recognition in children and adolescents with attention-deficit/hyperactivity disorder (ADHD)

Children with attention-deficit/hyperactivity disorder (ADHD) are impaired in social adaptation and display deficits in social competence. Deficient emotion recognition has been discussed to underlie these social problems. However, comorbid conduct problems have not been considered in the majority of studies conducted so far, and the influence of medication on emotion recognition has rarely been studied. Here, emotion recognition performance was assessed in children with ADHD without medication compared with children with ADHD under stimulant medication and a matched control group. In order to rule out confounding by externalizing symptoms, children with comorbid conduct problems were excluded. Video clips with neutral faces developing a basic emotion (happiness, sadness, disgust, fear and anger) were presented in order to assess emotion recognition. Results indicated between-group differences neither concerning the number of correctly identified emotions nor concerning reaction times and their standard deviations. Thus, we suggest that ADHD per se is not associated with deficits in emotion recognition.     

Evaluating the effectiveness of conservation site networks under climate change: accounting for uncertainty

We forecasted potential impacts of climate change on the ability of a network of key sites for bird conservation (Important Bird Areas; IBAs) to provide suitable climate for 370 bird species of current conservation concern in two Asian biodiversity hotspots: the Eastern Himalaya and Lower Mekong. Comparable studies have largely not accounted for uncertainty, which may lead to inappropriate conclusions. We quantified the contribution of four sources of variation (choice of general circulation models, emission scenarios and species distribution modelling methods and variation in species distribution data) to uncertainty in forecasts and tested if our projections were robust to these uncertainties. Declines in the availability of suitable climate within the IBA network by 2100 were forecast as ‘extremely likely’ for 45% of species, whereas increases were projected for only 2%. Thus, we predict almost 24 times as many ‘losers’ as ‘winners’. However, for no species was suitable climate ‘extremely likely’ to be completely lost from the network. Considerable turnover (median = 43%, 95% CI = 35–69%) in species compositions of most IBAs were projected by 2100. Climatic conditions in 47% of IBAs were projected as ‘extremely likely’ to become suitable for fewer priority species. However, no IBA was forecast to become suitable for more species. Variation among General Circulation Models and Species Distribution Models contributed most to uncertainty among forecasts. This uncertainty precluded firm conclusions for 53% of species and IBAs because 95% confidence intervals included projections of no change. Considering this uncertainty, however, allows robust recommendations concerning the remaining species and IBAs. Overall, while the IBA network will continue to sustain bird conservation, climate change will modify which species each site will be suitable for. Thus, adaptive management of the network, including modified site conservation strategies and facilitating species' movement among sites, is critical to ensure effective future conservation.     

Organization of Ca2+ release units in excitable smooth muscle of the guinea-pig urinary bladder

Ca(2+) release from internal stores (sarcoplasmic reticulum or SR) in smooth muscles is initiated either via pharmaco-mechanical coupling due to the action of an agonist and involving IP3 receptors, or via excitation-contraction coupling, mostly involving L-type calcium channels in the plasmalemma (DHPRs), and ryanodine receptors (RyRs), or Ca(2+) release channels of the SR. This work focuses attention on the structural basis for the coupling between DHPRs and RyRs in phasic smooth muscle cells of the guinea-pig urinary bladder. Immunolabeling shows that two proteins of the SR: calsequestrin and the RyR, and one protein the plasmalemma, the L-type channel or DHPR, are colocalized with each other within numerous, peripherally located sites located within the caveolar domains. Electron microscopy images from thin sections and freeze-fracture replicas identify feet in small peripherally located SR vesicles containing calsequestrin and distinctive large particles clustered within small membrane areas. Both feet and particle clusters are located within caveolar domains. Correspondence between the location of feet and particle clusters and of RyR- and DHPR-positive foci allows the conclusion that calsequestrin, RyRs, and L-type Ca(2+) channels are associated with peripheral couplings, or Ca(2+) release units, constituting the key machinery involved in excitation-contraction coupling. Structural analogies between smooth and cardiac muscle excitation-contraction coupling complexes suggest a common basic mechanism of action.     

Do mitochondria make nitric oxide? no?

Several papers have claimed that mitochondria contain nitric oxide synthase (NOS) and make nitric oxide (NO*) in amounts sufficient to affect mitochondrial respiration. However, we found that the addition of L-arginine or the NOS inhibitor L-NMMA to intact rat liver mitochondria did not have any effect on the respiratory rate in both State 3 and State 4. We did not detect mitochondrial NO* production by the oxymyoglobin oxidation assay, or electrochemically using an NO* electrode. An apparent NO* production detected by the Griess assay was identified as an artifact. NO* generated by eNOS added to the mitochondria could easily be detected, although succinate-supplemented mitochondria appeared to consume NO*. Our data show that NO* production by normal rat liver mitochondria cannot be detected in our laboratory, even though the levels of production claimed in the literature should easily have been measured by the techniques used. The implications for the putative mitochondrial NOS are discussed.     

Species-specific variation in the importance of the spectral quality gradient in canopies as a signal for photosynthetic resource partitioning

BACKGROUND AND AIMS: Plants adjust the distribution of photosynthetic capacity and chlorophyll to canopy density. The importance of the gradient in the red : far-red ratio (R : FR) relative to the irradiance gradient was studied for its perception with respect to this partitioning of photosynthetic resources. Whether the relative importance of these two signals varied between six species of different growth habit (Phaseolus vulgaris, Lysimachia vulgaris, Hedera helix, Ficus benjamina, Carex acutiformis and Brachypodium pinnatum) was investigated further. METHODS: Single leaves of plants were shaded in daylight by a spectrally neutral filter or a leaf. In another experiment, leaves were treated with supplemental FR. In most cases, treatment effects were evaluated after 2 weeks. KEY RESULTS: Nitrogen and photosynthetic capacity (Amax) per leaf area, parameters pertaining to between-leaf resource partitioning, were strongly reduced in neutral shade but not additionally by spectral leaf shade. Supplemental FR reduced these parameters also, except in Carex. Acceleration of induction of senescence was observed in spectral leaf shade in primary bean leaves. Amax per unit chlorophyll, a parameter pertaining to within-leaf resource partitioning, was reduced in neutral shade, but not in spectral leaf shade or supplemental FR. CONCLUSIONS: Signalling mechanisms associated with perception of the R : FR gradient in canopies were less important than those associated with the irradiance gradient for between-leaf and within-leaf partitioning of photosynthetic resources. The relative importance of the signals differed between species because Carex was the only species for which no indications were found for an involvement of the spectral gradient in perception of canopy density.