Overexpression of Neurospora crassa OR74A glutamate decarboxylase in Escherichia coli for efficient GABA production

This study investigated the effect of glutamate decarboxylase from Neurospora crassa OR74A on GABA production in Escherichia coli. GABA is one of the inhibitory neurotransmitters in the mammalian central nervous system, and can be used as a precursor of promising biopolymer Nylon 4. E. coli that overexpressed N. crassa glutamate decarboxylase was cultured at various pH levels and temperatures to determine optimum conditions for GABA production. When the recombinant E. coli strain was cultured at 30°C and pH 3, a final GABA concentration of 5.26 g/L was obtained from 10 g/L of monosodium glutamate (MSG), corresponding to a GABA yield of 86.23%.     

Aquaporin Trafficking in Plant Cells: An Emerging Membrane‐Protein Model

Aquaporins (AQPs) are channel proteins that facilitate the transport of water and small solutes across biological membranes. In plants, AQPs exhibit a high multiplicity of isoforms in relation to a high diversity of sub‐cellular localizations, at the plasma membrane (PM) and in various intracellular compartments. Some members also exhibit a dual localization in distinct cell compartments, whereas others show polarized or domain‐specific expression at the PM or tonoplast, respectively. A diversity of mechanisms controlling the routing of newly synthesized AQPs towards their destination membranes and involving diacidic motifs, phosphorylation or tetramer assembly is being uncovered. Recent approaches using single particle tracking, fluorescence correlation spectroscopy and fluorescence recovery after photobleaching have, in combination with pharmacological interference, stressed the peculiarities of AQP sub‐cellular dynamics in environmentally challenging conditions. A role for clathrin and sterol‐rich domains in cell surface dynamics and endocytosis of PM AQPs was uncovered. These recent advances provide deep insights into the cellular mechanisms of water transport regulation in plants. They also point to AQPs as an emerging model for studying the sub‐cellular dynamics of plant membrane proteins .     

Factors Associated with Dengue Shock Syndrome: A Systematic Review and Meta-Analysis

Background

The pathogenesis of dengue shock syndrome (DSS, grade 3 and 4) is not yet completely understood. Several factors are reportedly associated with DSS, a more severe form of dengue infection that reportedly causes 50 times higher mortality compared to that of dengue patients without DSS. However, the results from these reports remain inconclusive. To better understand the epidemiology, clinical manifestation, and pathogenesis of DSS for development of new therapy, we systematically reviewed and performed a meta-analysis of relevant studies that reported factors in both DSS and dengue hemorrhagic fever (DHF, grade 1 and 2) patients.

Methods and Findings

PubMed, EMBASE, Scopus, Google Scholar, Dengue Bulletin, Cochrane Library, Virtual Health Library, and a manual search of reference lists of articles published before September 2010 were used to retrieve relevant studies. A meta-analysis using fixed- or random-effects models was used to calculate pooled odds ratios (OR) or event rate with corresponding 95% confidence intervals. Assessment of heterogeneity and publication bias, meta-regression analysis, subgroup analysis, sensitivity analysis, and analysis of factor-specific relationships were further performed. There were 198 studies constituting 203 data sets that met our eligibility criteria. Our meta-regression analysis showed a sustained reduction of DSS/dengue hemorrhagic fever (DHF) ratio over a period of 40 years in Southeast Asia, especially in Thailand. The meta-analysis revealed that age, female sex, neurological signs, nausea/vomiting, abdominal pain, gastrointestinal bleeding, hemoconcentration, ascites, pleural effusion, hypoalbuminemia, hypoproteinemia, hepatomegaly, levels of alanine transaminase and aspartate transaminase, thrombocytopenia, prothrombin time, activated partial thromboplastin time, fibrinogen level, primary/secondary infection, and dengue virus serotype-2 were significantly associated with DSS when pooling all original relevant studies.

Conclusions

The results improve our knowledge of the pathogenesis of DSS by identifying the association between the epidemiology, clinical signs, and biomarkers involved in DSS.     

Mapping the Genetic Variation of Regional Brain Volumes as Explained by All Common SNPs from the ADNI Study

Typically twin studies are used to investigate the aggregate effects of genetic and environmental influences on brain phenotypic measures. Although some phenotypic measures are highly heritable in twin studies, SNPs (single nucleotide polymorphisms) identified by genome-wide association studies (GWAS) account for only a small fraction of the heritability of these measures. We mapped the genetic variation (the proportion of phenotypic variance explained by variation among SNPs) of volumes of pre-defined regions across the whole brain, as explained by 512,905 SNPs genotyped on 747 adult participants from the Alzheimer''s Disease Neuroimaging Initiative (ADNI). We found that 85% of the variance of intracranial volume (ICV) (p = 0.04) was explained by considering all SNPs simultaneously, and after adjusting for ICV, total grey matter (GM) and white matter (WM) volumes had genetic variation estimates near zero (p = 0.5). We found varying estimates of genetic variation across 93 non-overlapping regions, with asymmetry in estimates between the left and right cerebral hemispheres. Several regions reported in previous studies to be related to Alzheimer''s disease progression were estimated to have a large proportion of volumetric variance explained by the SNPs.     

Reconstructing Native American Migrations from Whole-Genome and Whole-Exome Data

There is great scientific and popular interest in understanding the genetic history of populations in the Americas. We wish to understand when different regions of the continent were inhabited, where settlers came from, and how current inhabitants relate genetically to earlier populations. Recent studies unraveled parts of the genetic history of the continent using genotyping arrays and uniparental markers. The 1000 Genomes Project provides a unique opportunity for improving our understanding of population genetic history by providing over a hundred sequenced low coverage genomes and exomes from Colombian (CLM), Mexican-American (MXL), and Puerto Rican (PUR) populations. Here, we explore the genomic contributions of African, European, and especially Native American ancestry to these populations. Estimated Native American ancestry is in MXL, in CLM, and in PUR. Native American ancestry in PUR is most closely related to populations surrounding the Orinoco River basin, confirming the Southern America ancestry of the Taíno people of the Caribbean. We present new methods to estimate the allele frequencies in the Native American fraction of the populations, and model their distribution using a demographic model for three ancestral Native American populations. These ancestral populations likely split in close succession: the most likely scenario, based on a peopling of the Americas thousand years ago (kya), supports that the MXL Ancestors split kya, with a subsequent split of the ancestors to CLM and PUR kya. The model also features effective populations of in Mexico, in Colombia, and in Puerto Rico. Modeling Identity-by-descent (IBD) and ancestry tract length, we show that post-contact populations also differ markedly in their effective sizes and migration patterns, with Puerto Rico showing the smallest effective size and the earlier migration from Europe. Finally, we compare IBD and ancestry assignments to find evidence for relatedness among European founders to the three populations.     

Comparison of Barium and Arsenic Concentrations in Well Drinking Water and in Human Body Samples and a Novel Remediation System for These Elements in Well Drinking Water

Health risk for well drinking water is a worldwide problem. Our recent studies showed increased toxicity by exposure to barium alone (≤700 µg/L) and coexposure to barium (137 µg/L) and arsenic (225 µg/L). The present edition of WHO health-based guidelines for drinking water revised in 2011 has maintained the values of arsenic (10 µg/L) and barium (700 µg/L), but not elements such as manganese, iron and zinc. Nevertheless, there have been very few studies on barium in drinking water and human samples. This study showed significant correlations between levels of arsenic and barium, but not its homologous elements (magnesium, calcium and strontium), in urine, toenail and hair samples obtained from residents of Jessore, Bangladesh. Significant correlation between levels of arsenic and barium in well drinking water and levels in human urine, toenail and hair samples were also observed. Based on these results, a high-performance and low-cost adsorbent composed of a hydrotalcite-like compound for barium and arsenic was developed. The adsorbent reduced levels of barium and arsenic from well water in Bangladesh and Vietnam to <7 µg/L within 1 min. Thus, we have showed levels of arsenic and barium in humans and propose a novel remediation system.     

Initial Contact of Glioblastoma Cells with Existing Normal Brain Endothelial Cells Strengthen the Barrier Function via Fibroblast Growth Factor 2 Secretion: A New In Vitro Blood–Brain Barrier Model

Glioblastoma multiforme (GBM) cells invade along the existing normal capillaries in brain. Normal capillary endothelial cells function as the blood–brain barrier (BBB) that limits permeability of chemicals into the brain. To investigate whether GBM cells modulate the BBB function of normal endothelial cells, we developed a new in vitro BBB model with primary cultures of rat brain endothelial cells (RBECs), pericytes, and astrocytes. Cells were plated on a membrane with 8 μm pores, either as a monolayer or as a BBB model with triple layer culture. The BBB model consisted of RBEC on the luminal side as a bottom, and pericytes and astrocytes on the abluminal side as a top of the chamber. Human GBM cell line, LN-18 cells, or lung cancer cell line, NCI-H1299 cells, placed on either the RBEC monolayer or the BBB model increased the transendothelial electrical resistance (TEER) values against the model, which peaked within 72 h after the tumor cell application. The TEER value gradually returned to baseline with LN-18 cells, whereas the value quickly dropped to the baseline in 24 h with NCI-H1299 cells. NCI-H1299 cells invaded into the RBEC layer through the membrane, but LN-18 cells did not. Fibroblast growth factor 2 (FGF-2) strengthens the endothelial cell BBB function by increased occludin and ZO-1 expression. In our model, LN-18 and NCI-H1299 cells secreted FGF-2, and a neutralization antibody to FGF-2 inhibited LN-18 cells enhanced BBB function. These results suggest that FGF-2 would be a novel therapeutic target for GBM in the perivascular invasive front.     

Molecular Diagnosis of an Ocular Toxocariasis Patient in Vietnam

An ocular Toxocara canis infection is reported for the first time in Vietnam. A 34-year-old man residing in a village of Son La Province, North Vietnam, visited the National Eye Hospital (NEH) in August 2011. He felt a bulge-sticking pain in his left eye and loss of vision occurred over 3 months before visiting the hospital. The eye examination in the hospital showed damage of the left eye, red eye, retinal fibrosis, retinal detachment, inflammation of the eye tissues, retinal granulomas, and a parasitic cyst inside. A larva of Toxocara was collected with the cyst by a medical doctor by surgery. Comparison of 264 nucleotides of internal transcribed spacer 2 (ITS2) of ribosomal DNA was done between our Vietnamese Toxocara canis and other Toxocara geographical isolates, including Chinese T. canis, Japanese T. canis, Sri Lankan T. canis, and Iranian T. canis. The nucleotide homology was 97-99%, when our T. canis was compared with geographical isolates. Identification of a T. canis infection in the eye by a molecular method was performed for the first time in Vietnam.