616 research outputs found

    Magnetic Curves According to Bishop Frame and Type-2 Bishop Frame in Euclidean 3-Space

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    In this paper, we define the notions of T-magnetic, N1-magnetic, N2-magnetic curves according to Bishop frame and ξ1-magnetic, ξ2-magnetic, B-magnetic curves according to type-2 Bishop frame in Euclidean 3-space. Also, we obtain the magnetic vector field V when the curve is T-magnetic, N1-magnetic, N2-magnetic trajectory of V according to Bishop frame and ξ1-magnetic, ξ2-magnetic, B-magnetic trajectory of V according to type-2 Bishop frame. Finally, we give an example for magnetic curves according to Bishop frame and type-2 Bishop frame

    Atmospheric transport and chemistry of trace gases in LMDz5B: evaluation and implications for inverse modelling

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    Representation of atmospheric transport is a major source of error in the estimation of greenhouse gas sources and sinks by inverse modelling. Here we assess the impact on trace gas mole fractions of the new physical parameterizations recently implemented in the atmospheric global climate model LMDz to improve vertical diffusion, mesoscale mixing by thermal plumes in the planetary boundary layer (PBL), and deep convection in the troposphere. At the same time, the horizontal and vertical resolution of the model used in the inverse system has been increased. The aim of this paper is to evaluate the impact of these developments on the representation of trace gas transport and chemistry, and to anticipate the implications for inversions of greenhouse gas emissions using such an updated model. Comparison of a one-dimensional version of LMDz with large eddy simulations shows that the thermal scheme simulates shallow convective tracer transport in the PBL over land very efficiently, and much better than previous versions of the model. This result is confirmed in three-dimensional simulations, by a much improved reproduction of the radon-222 diurnal cycle. However, the enhanced dynamics of tracer concentrations induces a stronger sensitivity of the new LMDz configuration to external meteorological forcings. At larger scales, the inter-hemispheric exchange is slightly slower when using the new version of the model, bringing them closer to observations. The increase in the vertical resolution (from 19 to 39 layers) significantly improves the representation of stratosphere/troposphere exchange. Furthermore, changes in atmospheric thermodynamic variables, such as temperature, due to changes in the PBL mixing modify chemical reaction rates, which perturb chemical equilibriums of reactive trace gases. One implication of LMDz model developments for future inversions of greenhouse gas emissions is the ability of the updated system to assimilate a larger amount of high-frequency data sampled at high-variability stations. Others implications are discussed at the end of the paper

    Simple sequence repeat-based assessment of genetic diversity in 'Dimrit' and 'Gemre' grapevine accessions from Turkey

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    It is widely believed that Turkey has played an important role in the evolution of modern day grapes due to its unique geographical location with close proximity to the regions of grape diversity. Despite this, the rich grape germplasm found in Turkey has not been sufficiently analyzed genetically. In this study, 31 grapevine accessions from 'Dimrit' (or 'Dilmit') and 'Gemre' grape groups were genetically analyzed at eight SSR (microsatellite) loci (VVS2, VVMD5, VVMD7, VVMD24, VVMD27, VVMD28, VrZAG62 and VrZAG79) and for a number of ampeolographic characteristics. These analyses identified sufficient genetic diversity between these two grape groups that, in general, clustered separately in the dendrogram constructed based on the SSR data. However, the ecogeographical distribution and genetic relationship of the genotypes did not show any significant correlation. Two 'Gemre' accessions were determined as genetically identical. In addition, one case of synonym and several cases of homonym genotypes were identified. The results reported here are important first steps towards better characterization of these grape genotypes and would aid future germplasm management and breeding efforts.

    Genetic characterization of grape (Vitis vinifera L.) germplasm from Southeast Anatolia by SSR markers

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    Southeast Anatolia is located in close proximity to the center of origin of grapes and is an important grape producing area of Turkey. The important location of this region for grape genetic diversity together with its diverse ecological conditions may have led to the development of grape germplasm that is unique to this region. However, so far little has been done to genetically analyze this grape germplasm. In this study, we genetically analyzed 55 grape cultivars originating from six different provinces of this region using 14 simple sequence repeat (SSR) loci and a number of ampeolographic characteristics. Based on these analyses, one case of synonymous and four cases of homonymous grape cultivars were identified. The contribution of our results to better characterization of the grape germplasm of the region as well as future germplasm management and breeding efforts is discussed.

    Natural history of Arabidopsis thaliana and oomycete symbioses

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    Molecular ecology of plant–microbe interactions has immediate significance for filling a gap in knowledge between the laboratory discipline of molecular biology and the largely theoretical discipline of evolutionary ecology. Somewhere in between lies conservation biology, aimed at protection of habitats and the diversity of species housed within them. A seemingly insignificant wildflower called Arabidopsis thaliana has an important contribution to make in this endeavour. It has already transformed botanical research with deepening understanding of molecular processes within the species and across the Plant Kingdom; and has begun to revolutionize plant breeding by providing an invaluable catalogue of gene sequences that can be used to design the most precise molecular markers attainable for marker-assisted selection of valued traits. This review describes how A. thaliana and two of its natural biotrophic parasites could be seminal as a model for exploring the biogeography and molecular ecology of plant–microbe interactions, and specifically, for testing hypotheses proposed from the geographic mosaic theory of co-evolution

    High resolution mapping of a novel late blight resistance gene Rpi-avll, from the wild Bolivian species Solanum avilesii

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    Both Mexico and South America are rich in Solanum species that might be valuable sources of resistance (R) genes to late blight (Phytophthora infestans). Here, we focus on an R gene present in the diploid Bolivian species S. avilesii. The genotype carrying the R gene was resistant to eight out of 10 Phytophthora isolates of various provenances. The identification of a resistant phenotype and the generation of a segregating population allowed the mapping of a single dominant R gene, Rpi-avl1, which is located in an R gene cluster on chromosome 11. This R gene cluster is considered as an R gene “hot spot”, containing R genes to at least five different pathogens. High resolution mapping of the Rpi-avl1 gene revealed a marker co-segregating in 3890 F1 individuals, which may be used for marker assisted selection in breeding programs and for further cloning of Rpi-avl

    A gamma-lactamase from cereal infecting Fusarium spp. catalyses the first step in the degradation of the benzoxazolinone class of phytoalexins

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    The benzoxazolinone class of phytoalexins are released by wheat, maize, rye and other agriculturally important species in the Poaceae family upon pathogen attack. Benzoxazolinones show antimicrobial effects on plant pathogens, but certain fungi have evolved mechanisms to actively detoxify these compounds which may contribute to the virulence of the pathogens. In many Fusarium spp. a cluster of genes is thought to be involved in the detoxification of benzoxazolinones. However, only one enzyme encoded in the cluster has been unequivocally assigned a role in this process. The first step in the detoxification of benzoxazolinones in Fusarium spp. involves the hydrolysis of a cyclic ester bond. This reaction is encoded by the FDB1 locus in F. verticillioides but the underlying gene is yet to be cloned. We previously proposed that FDB1 encodes a γ-lactamase, and here direct evidence for this is presented. Expression analyses in the important wheat pathogen F. pseudograminearum demonstrated that amongst the three predicted γ-lactamase genes only the one designated as FDB1, part of the proposed benzoxazolinone cluster in F. pseudograminearum, was strongly responsive to exogenous benzoxazolinone application. Analysis of independent F. pseudograminearum and F. graminearum FDB1 gene deletion mutants, as well as biochemical assays, demonstrated that the γ-lactamase enzyme, encoded by FDB1, catalyses the first step in detoxification of benzoxazolinones. Overall, our results support the notion that Fusarium pathogens that cause crown rot and head blight on wheat have adopted strategies to overcome host-derived chemical defences

    Giant cervicothoracic extradural arachnoid cyst: case report

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    The pathogenesis, etiology, and treatment of the spinal arachnoid cyst have not been well established because of its rarity. A 57-year-old male was presented with spastic quadriparesis predominantly on the left side. His radiological examination showed widening of the cervical spinal canal and left neural foramina due to a cerebrospinal fluid - filled extradural cyst that extended from C2 to T2 level. The cyst was located left anterolaterally, compressing the spinal cord. Through a C4–T2 laminotomy, the cyst was excised totally and the dural defect was repaired. Several features of the reported case, such as cyst size, location, and clinical features make it extremely unusual. The case is discussed in light of the relevant literature

    RBPDB: a database of RNA-binding specificities

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    The RNA-Binding Protein DataBase (RBPDB) is a collection of experimental observations of RNA-binding sites, both in vitro and in vivo, manually curated from primary literature. To build RBPDB, we performed a literature search for experimental binding data for all RNA-binding proteins (RBPs) with known RNA-binding domains in four metazoan species (human, mouse, fly and worm). In total, RPBDB contains binding data on 272 RBPs, including 71 that have motifs in position weight matrix format, and 36 sets of sequences of in vivo-bound transcripts from immunoprecipitation experiments. The database is accessible by a web interface which allows browsing by domain or by organism, searching and export of records, and bulk data downloads. Users can also use RBPDB to scan sequences for RBP-binding sites. RBPDB is freely available, without registration at http://rbpdb.ccbr.utoronto.ca/
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