Multilocus enzyme electrophoresis analysis of Trypanosoma cruzi isolates from a geographically restricted endemic area for Chagas' disease in Argentina

A set of 65 Trypanosoma cruzi stocks from dogs, opossums, insect vectors and humans was isolated in a geographically restricted endemic area for Chagas' disease in Argentina and was analysed by multilocus enzyme electrophoresis for 15 loci. The results show that at least five multilocus genotypes (clonets) circulate in the study area, one belonging to T. cruzi IIe, one to T. cruzi IId and three clonets belonging to T. cruzi I; and they confirm the presence of these lineages in the country. The three clonets attributed to T. cruzi I were identical to each other for all loci except for Sod-2, where three different patterns were identified. These patterns suggest the presence of two homozygous genotypes and one heterozygous genotype. Our results also suggest association of clonet IIe with dogs, clonet IId with humans and the three T. cruzi I clonets with Didelphis albiventris. On the other hand, there was no significant association between Triatoma infestans and any particular clonet circulating in the area. These findings are consistent with the hypothesis of natural selection, from mixed populations of T. cruzi in vectors, toward more restricted populations in mammals. The epidemiological implications of the possible selection of different clonets by different mammal hosts and the significance of two homozygous genotypes and one heterozygous genotype for the Sod-2 locus are discussed.     

Adenosine A<Subscript>2A</Subscript> receptor regulates expression of vascular endothelial growth factor in feto-placental endothelium from normal and late-onset pre-eclamptic pregnancies

We aim to investigate whether A_2A/nitric oxide-mediated regulation of vascular endothelial growth factor (VEGF) expression is impaired in feto-placental endothelial cells from late-onset pre-eclampsia. Cultures of human umbilical vein endothelial cells (HUVECs) and human placental microvascular endothelial cells (hPMECs) from normal and pre-eclamptic pregnancies were used. Assays by using small interference RNA (siRNA) for A_2A were performed, and transfected cells were used for estimation of messenger RNA (mRNA) levels of VEGF, as well as for cell proliferation and angiogenesis in vitro. CGS-21680 (A_2A agonist, 24 h) increases HUVEC and hPMEC proliferation in a dose response manner. Furthermore, similar to CGS-21680, the nitric oxide donor, S-nitroso-N-acetyl-penicillamine oxide (SNAP), increased cell proliferation in a dose response manner (logEC₅₀ 10^?9.2 M). In hPMEC, CGS-21680 increased VEGF protein levels in both normal (～1.5-fold) and pre-eclamptic pregnancies (～1.2-fold), an effect blocked by the A_2A antagonist, ZM-241385 (10^?5 M) and the inhibitor of NO synthase, N _ω-nitro-L-arginine methyl ester hydrochloride (L-NAME). Subsequently, SNAP partially recovered cell proliferation and in vitro angiogenesis capacity of cells from normal pregnancies exposed to siRNA for A_2A. CGS-21680 also increased (～1.5-fold) the level of VEGF mRNA in HUVEC from normal pregnancies, but not in pre-eclampsia. Additionally, transfection with siRNA for A_2A decrease (～30 %) the level of mRNA for VEGF in normal pregnancy compared to untransfected cells, an effect partially reversed by co-incubation with SNAP. The A_2A-NO-VEGF pathway is present in endothelium from microcirculation and macrocirculation in both normal and pre-eclamptic pregnancies. However, NO signaling pathway seems to be impaired in HUVEC from pre-eclampsia.     

The altitudinal limit of Leptohyphes Eaton, 1882 and Lachlania Hagen, 1868 (Ephemeroptera: Leptohyphidae,Oligoneuriidae) in Ecuadorian Andes streams: searching for mechanisms

We explored mechanisms determining the upper altitudinal limit of ephemeropterans from two different genera: Leptohyphes Eaton, 1882 Eaton, A.E. (1882), ?An Announcement of New Genera of the Ephemeridae?, The Entomologist's Monthly Magazine, 18, 207–208. [Google Scholar] (Leptohyphidae) and Lachlania Hagen, 1868 Hagen, H.A. (1868), ?On Lachlania Abnormis: A New Genus and Species from Cuba Belonging to the Ephemerina?, Proceedings of the Boston Society of Natural History, 11, 372–375. [Google Scholar] (Oligoneuriidae). For this, we (1) surveyed the two taxa in 165 stream sites along a wide altitudinal gradient; (2) sampled benthic fauna at short altitudinal intervals along a stream, from 2780 to 3150 m above sea level; (3) collected adults at the lowest and highest sites; and (4) transplanted nymphs from the lowest to the highest study site in our stream to determine survival over time. Densities of the two taxa declined gradually with altitude and both disappeared between 2950 and 3080 m a.s.l. The upper altitudinal limit in the stream seemed to be most closely related to mean oxygen saturation, temperature, and current velocity. Adults were collected where the nymphs were found, but not at the upstream site where the nymphs were absent, implying limited upstream dispersal of adults and some of the altitudinal constraint lying at the adult stage. Short-term survival of transplanted nymphs was lower than that of controls, suggesting that the distribution was limited at the juvenile stage, and that at least some of the altitudinal constraint is related to the abiotic stream environment.     

A Novel Method to Evaluate the Community Built Environment Using Photographs – Environmental Profile of a Community Health (EPOCH) Photo Neighbourhood Evaluation Tool

Background

Previous research has shown that environments with features that encourage walking are associated with increased physical activity. Existing methods to assess the built environment using geographical information systems (GIS) data, direct audit or large surveys of the residents face constraints, such as data availability and comparability, when used to study communities in countries in diverse parts of the world. The aim of this study was to develop a method to evaluate features of the built environment of communities using a standard set of photos. In this report we describe the method of photo collection, photo analysis instrument development and inter-rater reliability of the instrument.

Methods/Principal Findings

A minimum of 5 photos were taken per community in 86 communities in 5 countries according to a standard set of instructions from a designated central point of each community by researchers at each site. A standard pro forma derived from reviewing existing instruments to assess the built environment was developed and used to score the characteristics of each community. Photo sets from each community were assessed independently by three observers in the central research office according to the pro forma and the inter-rater reliability was compared by intra-class correlation (ICC). Overall 87% (53 of 60) items had an ICC of ≥0.70, 7% (4 of 60) had an ICC between 0.60 and 0.70 and 5% (3 of 60) items had an ICC ≤0.50.

Conclusions/Significance

Analysis of photos using a standardized protocol as described in this study offers a means to obtain reliable and reproducible information on the built environment in communities in very diverse locations around the world. The collection of the photographic data required minimal training and the analysis demonstrated high reliability for the majority of items of interest.     

Introduction pathways of economically costly invasive alien species

Biological Invasions - Introduction pathways play a pivotal role in the success of Invasive Alien Species (IAS)—the subset of alien species that have a negative environmental and/or...     

Regulation of AMPA receptor surface diffusion by PSD-95 slots

Excitatory synaptic transmission is largely mediated by AMPA receptors (AMPARs) present at the postsynaptic density. Recent studies in single molecule tracking of AMPAR has revealed that extrasynaptic AMPARs are highly mobile and thus might serve as a readily available pool for their synaptic recruitment during synaptic plasticity events such as long-term potentiation (LTP). Because this hypothesis relies on the cell's ability to increase the number of diffusional traps or 'slots' at synapses during LTP, we will review a number of protein-protein interactions that might impact AMPARs lateral diffusion and thus potentially serve as slots. Recent studies have identified the interaction between the AMPAR-Stargazin complex and PSD-95 as the minimal components of the diffusional trapping slot. We will overview the molecular basis of this critical interaction, its activity-dependent regulation and its potential contribution to LTP.     

QTL mapping in outbred tetraploid (and diploid) diallel populations

Over the last decade, multiparental populations have become a mainstay of genetics research in diploid species. Our goal was to extend this paradigm to autotetraploids by developing software for quantitative trait locus (QTL) mapping in connected F1 populations derived from a set of shared parents. For QTL discovery, phenotypes are regressed on the dosage of parental haplotypes to estimate additive effects. Statistical properties of the model were explored by simulating half-diallel diploid and tetraploid populations with different population sizes and numbers of parents. Across scenarios, the number of progeny per parental haplotype (pph) largely determined the statistical power for QTL detection and accuracy of the estimated haplotype effects. Multiallelic QTL with heritability 0.2 were detected with 90% probability at 25 pph and genome-wide significance level 0.05, and the additive haplotype effects were estimated with over 90% accuracy. Following QTL discovery, the software enables a comparison of models with multiple QTL and nonadditive effects. To illustrate, we analyzed potato tuber shape in a half-diallel population with three tetraploid parents. A well-known QTL on chromosome 10 was detected, for which the inclusion of digenic dominance lowered the Deviance Information Criterion (DIC) by 17 points compared to the additive model. The final model also contained a minor QTL on chromosome 1, but higher-order dominance and epistatic effects were excluded based on the DIC. In terms of practical impacts, the software is already being used to select offspring based on the effect and dosage of particular haplotypes in breeding programs.     

Relationships between stream macroinvertebrate communities and new flood‐based indices of glacial influence

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It takes guts to grow a brain: Increasing evidence of the important role of the intestinal microflora in neuro- and immune-modulatory functions during development and adulthood

A new study entitled "Normal gut microbiota modulates brain development and behavior", published in the Proceedings of the National Academy of Sciences, requires that we reconsider the notion that the brain is an immune-privileged site. The authors demonstrate that intestinal microbiota must be present within a set time-frame for normal synaptogenesis to occur in the brain. In the absence of intestinal microbiota, histopathological and behavioral abnormalities arise. These observations necessitate a new look at the many interconnections of the immune system and the brain, suggesting new frontiers for research and new therapeutic strategies for neurodevelopmental diseases.