101 research outputs found
The bldC developmental locus of Streptomyces coelicolor encodes a member of a family of small DNA-binding proteins related to the DNA-binding domains of the MerR family.
The bldC locus, required for formation of aerial hyphae in Streptomyces coelicolor, was localized by map-based cloning to the overlap between cosmids D17 and D25 of a minimal ordered library. Subcloning and sequencing showed that bldC encodes a member of a previously unrecognized family of small (58- to 78-residue) DNA-binding proteins, related to the DNA-binding domains of the MerR family of transcriptional activators. BldC family members are found in a wide range of gram-positive and gram-negative bacteria. Constructed {Delta}bldC mutants were defective in differentiation and antibiotic production. They failed to form an aerial mycelium on minimal medium and showed severe delays in aerial mycelium formation on rich medium. In addition, they failed to produce the polyketide antibiotic actinorhodin, and bldC was shown to be required for normal and sustained transcription of the pathway-specific activator gene actII-orf4. Although {Delta}bldC mutants produced the tripyrrole antibiotic undecylprodigiosin, transcripts of the pathway-specific activator gene (redD) were reduced to almost undetectable levels after 48 h in the bldC mutant, in contrast to the bldC+ parent strain in which redD transcription continued during aerial mycelium formation and sporulation. This suggests that bldC may be required for maintenance of redD transcription during differentiation. bldC is expressed from a single promoter. S1 nuclease protection assays and immunoblotting showed that bldC is constitutively expressed and that transcription of bldC does not depend on any of the other known bld genes. The bldC18 mutation that originally defined the locus causes a Y49C substitution that results in instability of the protein
Computing the Clique-width of Cactus Graphs
Similar to the tree-width (twd), the clique-width (cwd) is an invariant of graphs. A well known relationship between tree-width and clique-width is that cwd(G) ≤ 3 · 2twd(G)−1. It is also known that tree-width of Cactus graphs is 2, therefore the clique-width for those graphs is smaller or equal than 6. In this paper, it is shown that the clique-width of Cactus graphs is smaller or equal to 4 and we present a polynomial time algorithm which computes exactly a 4-expression
Thermal model of a solar concentration cooker: a parameter variation study to estimate thermal properties
Se realiza una variación de algunos parámetros de diseño para estimar propiedades térmicas que caracterizan una estufa solar, tomando de base un modelo térmico que reproduce experimentalmente el comportamiento de una estufa en base a un concentrador parabólico compuesto (CPC) de revolución. El modelo se presenta en términos de un sistema acoplado de tres ecuaciones diferenciales no lineales, que son resultado de considerar el balance de flujo de calor para algunos de los componentes del dispositivo, las cuales se resuelven numéricamente. Se calculan las temperaturas para el fluido, los reflectores y el contenedor de la estufa solar, en función del tiempo, a partir de eso, se infieren los valores para la potencia de cocción estándar y el rendimiento térmico.This document describes the development of a thermal model to explain the behavior of a solar concentration cooker. The model is presented in terms of a coupled system consisting of three ordinary, differential non-lineal equations used to calculate average temperatures of the surface of the reflectors, the surface of the container, and the liquid placed inside the container. Numerical results compared to measurements from experimental tests show that good concordance was obtained. A study of variation was conducted using some of the design parameters of the solar cooker to estimate standard cooking power and thermal efficiency. We conclude that the parameter ‘emittance of selective absorbent film’ on the surface of the cooking pot exerts the greatest influence on the thermal properties assessed.Peer Reviewe
Wavefront reconstruction of discontinuous phase objects from optical deflectometry
One of the challenges in phase measuring deflectometry is to retrieve the
wavefront from objects that present discontinuities or non-differentiable
gradient fields. Here, we propose the integration of such gradients fields
based on an Lp-norm minimization problem. The solution of this problem results
in a nonlinear partial differential equation, which can be solved with a fast
and well-known numerical methods and doesn't depend on external parameters.
Numerical reconstructions on both synthetic and experimental data are presented
that demonstrate the capability of the proposed method
CNVassoc: Association analysis of CNV data using R
Background: Copy number variants (CNV) are a potentially important component of the genetic contribution to
risk of common complex diseases. Analysis of the association between CNVs and disease requires that uncertainty
in CNV copy-number calls, which can be substantial, be taken into account; failure to consider this uncertainty can
lead to biased results. Therefore, there is a need to develop and use appropriate statistical tools. To address this
issue, we have developed CNVassoc, an R package for carrying out association analysis of common copy number
variants in population-based studies. This package includes functions for testing for association with different
classes of response variables (e.g. class status, censored data, counts) under a series of study designs (case-control,
cohort, etc) and inheritance models, adjusting for covariates. The package includes functions for inferring copy
number (CNV genotype calling), but can also accept copy number data generated by other algorithms (e.g.
CANARY, CGHcall, IMPUTE).
Results: Here we present a new R package, CNVassoc, that can deal with different types of CNV arising from
different platforms such as MLPA o aCGH. Through a real data example we illustrate that our method is able to
incorporate uncertainty in the association process. We also show how our package can also be useful when
analyzing imputed data when analyzing imputed SNPs. Through a simulation study we show that CNVassoc
outperforms CNVtools in terms of computing time as well as in convergence failure rate.
Conclusions: We provide a package that outperforms the existing ones in terms of modelling flexibility, power,
convergence rate, ease of covariate adjustment, and requirements for sample size and signal quality. Therefore, we
offer CNVassoc as a method for routine use in CNV association studiesThis work has been supported by the Spanish Ministry of
Science and Innovation (MTM2008-02457 to JRG, BIO2009-12458 to RD-U
and statistical genetics network MTM2010-09526-E (subprograma MTM) to
JRG, IS, GL and RD-U). GL is supported by the Juan de la Cierva Program of
the Spanish Ministry of Science and Innovation
Evaluation of organic and inorganic residues for organic production systems and small properties of Paraguay
The objective of this study was to evaluate the effect of organic and inorganic residues in the soil and agricultural products of the small property. Were evaluated doses of ash obtained from the soybean processing industry, doses of compost made from residues of the sugar industry and dose of bovine manure from the farm itself.CONACYT – Consejo Nacional de Ciencia y TecnologíaPROCIENCI
Novel Association Strategy with Copy Number Variation for Identifying New Risk Loci of Human Diseases
Copy number variations (CNV) are important causal genetic variations for human disease; however, the lack of a statistical model has impeded the systematic testing of CNVs associated with disease in large-scale cohort.Here, we developed a novel integrated strategy to test CNV-association in genome-wide case-control studies. We converted the single-nucleotide polymorphism (SNP) signal to copy number states using a well-trained hidden Markov model. We mapped the susceptible CNV-loci through SNP site-specific testing to cope with the physiological complexity of CNVs. We also ensured the credibility of the associated CNVs through further window-based CNV-pattern clustering. Genome-wide data with seven diseases were used to test our strategy and, in total, we identified 36 new susceptible loci that are associated with CNVs for the seven diseases: 5 with bipolar disorder, 4 with coronary artery disease, 1 with Crohn's disease, 7 with hypertension, 9 with rheumatoid arthritis, 7 with type 1 diabetes and 3 with type 2 diabetes. Fifteen of these identified loci were validated through genotype-association and physiological function from previous studies, which provide further confidence for our results. Notably, the genes associated with bipolar disorder converged in the phosphoinositide/calcium signaling, a well-known affected pathway in bipolar disorder, which further supports that CNVs have impact on bipolar disorder.Our results demonstrated the effectiveness and robustness of our CNV-association analysis and provided an alternative avenue for discovering new associated loci of human diseases
Antimicrobial resistance among migrants in Europe: a systematic review and meta-analysis
BACKGROUND: Rates of antimicrobial resistance (AMR) are rising globally and there is concern that increased migration is contributing to the burden of antibiotic resistance in Europe. However, the effect of migration on the burden of AMR in Europe has not yet been comprehensively examined. Therefore, we did a systematic review and meta-analysis to identify and synthesise data for AMR carriage or infection in migrants to Europe to examine differences in patterns of AMR across migrant groups and in different settings. METHODS: For this systematic review and meta-analysis, we searched MEDLINE, Embase, PubMed, and Scopus with no language restrictions from Jan 1, 2000, to Jan 18, 2017, for primary data from observational studies reporting antibacterial resistance in common bacterial pathogens among migrants to 21 European Union-15 and European Economic Area countries. To be eligible for inclusion, studies had to report data on carriage or infection with laboratory-confirmed antibiotic-resistant organisms in migrant populations. We extracted data from eligible studies and assessed quality using piloted, standardised forms. We did not examine drug resistance in tuberculosis and excluded articles solely reporting on this parameter. We also excluded articles in which migrant status was determined by ethnicity, country of birth of participants' parents, or was not defined, and articles in which data were not disaggregated by migrant status. Outcomes were carriage of or infection with antibiotic-resistant organisms. We used random-effects models to calculate the pooled prevalence of each outcome. The study protocol is registered with PROSPERO, number CRD42016043681. FINDINGS: We identified 2274 articles, of which 23 observational studies reporting on antibiotic resistance in 2319 migrants were included. The pooled prevalence of any AMR carriage or AMR infection in migrants was 25·4% (95% CI 19·1-31·8; I2 =98%), including meticillin-resistant Staphylococcus aureus (7·8%, 4·8-10·7; I2 =92%) and antibiotic-resistant Gram-negative bacteria (27·2%, 17·6-36·8; I2 =94%). The pooled prevalence of any AMR carriage or infection was higher in refugees and asylum seekers (33·0%, 18·3-47·6; I2 =98%) than in other migrant groups (6·6%, 1·8-11·3; I2 =92%). The pooled prevalence of antibiotic-resistant organisms was slightly higher in high-migrant community settings (33·1%, 11·1-55·1; I2 =96%) than in migrants in hospitals (24·3%, 16·1-32·6; I2 =98%). We did not find evidence of high rates of transmission of AMR from migrant to host populations. INTERPRETATION: Migrants are exposed to conditions favouring the emergence of drug resistance during transit and in host countries in Europe. Increased antibiotic resistance among refugees and asylum seekers and in high-migrant community settings (such as refugee camps and detention facilities) highlights the need for improved living conditions, access to health care, and initiatives to facilitate detection of and appropriate high-quality treatment for antibiotic-resistant infections during transit and in host countries. Protocols for the prevention and control of infection and for antibiotic surveillance need to be integrated in all aspects of health care, which should be accessible for all migrant groups, and should target determinants of AMR before, during, and after migration. FUNDING: UK National Institute for Health Research Imperial Biomedical Research Centre, Imperial College Healthcare Charity, the Wellcome Trust, and UK National Institute for Health Research Health Protection Research Unit in Healthcare-associated Infections and Antimictobial Resistance at Imperial College London
Chondroprotection by urocortin involves blockade of the mechanosensitive ion channel Piezo1
Osteoarthritis (OA) is characterised by progressive destruction of articular cartilage and chondrocyte cell death. Here, we show the expression of the endogenous peptide urocortin1 (Ucn1) and two receptor subtypes, CRF-R1 and CRF-R2, in primary human articular chondrocytes (AC) and demonstrate its role as an autocrine/paracrine pro-survival factor. This effect could only be removed using the CRF-R1 selective antagonist CP-154526, suggesting Ucn1 acts through CRF-R1 when promoting chondrocyte survival. This cell death was characterised by an increase in p53 expression, and cleavage of caspase 9 and 3. Antagonism of CRF-R1 with CP-154526 caused an accumulation of intracellular calcium (Ca2+) over time and cell death. These effects could be prevented with the non-selective cation channel blocker Gadolinium (Gd3+). Therefore, opening of a non-selective cation channel causes cell death and Ucn1 maintains this channel in a closed conformation. This channel was identified to be the mechanosensitive channel Piezo1. We go on to determine that this channel inhibition by Ucn1 is mediated initially by an increase in cyclic adenosine monophosphate (cAMP) and a subsequent inactivation of phospholipase A2 (PLA2), whose metabolites are known to modulate ion channels. Knowledge of these novel pathways may present opportunities for interventions that could abrogate the progression of OA
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