66 research outputs found

    ASSESSMENT OF THE RESISTANCE CONFERRED BY THE \u3ci\u3ebc-1\u3c/i\u3e ALLELES TO \u3ci\u3eBean common mosaic necrosis virus\u3c/i\u3e

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    INTRODUCTION: Bean common mosaic necrosis virus (BCMNV) is a potyvirus comprising several strains classified into two pathogroups according to the interactions with six recessive resistance alleles in common bean (1). These pathogroups (PGs), numbered III and VI, are defined by the ability (PG-VI) or inability (PG-III) of a BCMNV isolate to replicate in bean differential lines carrying bc-1 or bc-12 resistance alleles. The biological and molecular basis for this differential response of BCMNV isolates to the presence of bc-1 alleles is not known. Conversely, the genetic determinants involved in interactions of BCMNV strains with bc-1 resistance alleles have not yet been identified either. We performed a complete biological and molecular study of three isolates of BCMNV belonging to PG-III and VI, collected in California and in Oregon. Particular attention was paid to BCMNV isolates’ performance in common bean lines from host groups 2, 3, and 9, harboring bc-1 and bc-12 alleles. The data obtained suggest that the bc-1 alleles restricted systemic movement of PG-III isolates of BCMNV, while cell-tocell movement of the virus in inoculated leaves did not seem to be affected

    ASSESSMENT OF THE RESISTANCE CONFERRED BY THE \u3ci\u3ebc-1\u3c/i\u3e ALLELES TO \u3ci\u3eBean common mosaic necrosis virus\u3c/i\u3e

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    INTRODUCTION: Bean common mosaic necrosis virus (BCMNV) is a potyvirus comprising several strains classified into two pathogroups according to the interactions with six recessive resistance alleles in common bean (1). These pathogroups (PGs), numbered III and VI, are defined by the ability (PG-VI) or inability (PG-III) of a BCMNV isolate to replicate in bean differential lines carrying bc-1 or bc-12 resistance alleles. The biological and molecular basis for this differential response of BCMNV isolates to the presence of bc-1 alleles is not known. Conversely, the genetic determinants involved in interactions of BCMNV strains with bc-1 resistance alleles have not yet been identified either. We performed a complete biological and molecular study of three isolates of BCMNV belonging to PG-III and VI, collected in California and in Oregon. Particular attention was paid to BCMNV isolates’ performance in common bean lines from host groups 2, 3, and 9, harboring bc-1 and bc-12 alleles. The data obtained suggest that the bc-1 alleles restricted systemic movement of PG-III isolates of BCMNV, while cell-tocell movement of the virus in inoculated leaves did not seem to be affected

    Formal symplectic groupoid of a deformation quantization

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    We give a self-contained algebraic description of a formal symplectic groupoid over a Poisson manifold M. To each natural star product on M we then associate a canonical formal symplectic groupoid over M. Finally, we construct a unique formal symplectic groupoid `with separation of variables' over an arbitrary Kaehler-Poisson manifold.Comment: 41 page, Lemma 13, several typos and notations correcte

    Infinitesimal deformations of a formal symplectic groupoid

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    Given a formal symplectic groupoid GG over a Poisson manifold (M,π0)(M, \pi_0), we define a new object, an infinitesimal deformation of GG, which can be thought of as a formal symplectic groupoid over the manifold MM equipped with an infinitesimal deformation π0+ϵπ1\pi_0 + \epsilon \pi_1 of the Poisson bivector field π0\pi_0. The source and target mappings of a deformation of GG are deformations of the source and target mappings of GG. To any pair of natural star products (∗,∗~)(\ast, \tilde\ast) having the same formal symplectic groupoid GG we relate an infinitesimal deformation of GG. We call it the deformation groupoid of the pair (∗,∗~)(\ast, \tilde\ast). We give explicit formulas for the source and target mappings of the deformation groupoid of a pair of star products with separation of variables on a Kaehler- Poisson manifold. Finally, we give an algorithm for calculating the principal symbols of the components of the logarithm of a formal Berezin transform of a star product with separation of variables. This algorithm is based upon some deformation groupoid.Comment: 22 pages, the paper is reworked, new proofs are adde

    Properties of the transient X-ray pulsar Swift J1816.7--1613 and its optical companion

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    We present results of investigation of the poorly studied X-ray pulsar Swift J1816.7--1613 during its transition from the type I outburst to the quiescent state. Our studies are based on the data obtained from X-ray observatories \textit{Swift}, \textit{NuSTAR} and \textit{Chandra} alongside with the latest IR data from UKIDSS/GPS and \textit{Spitzer}/GLIMPSE surveys. The aim of the work is to determine parameters of the system: the strength of the neutron star magnetic field and the distance to the source, which are required for the interpretation of the source behaviour in the framework of physically motivated models. No cyclotron absorption line was detected in the broad-band energy spectrum. However, the timing analysis hints at the typical for the X-ray pulsars magnetic field from a few ×1011\times 10^{11} to a few ×1012\times 10^{12} G. We also estimated type of the IR-companion as a B0-2e star located at distance of 7--13~kpc.Comment: 8 pages, 7 figures, accepted for publication in A&

    X-ray pulsar XTE J1858+034: discovery of the cyclotron line and the revised optical identification

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    We present results of a detailed investigation of the poorly studied X-ray pulsar XTE J1858+034 based on the data obtained with the NuSTAR observatory during the outburst of the source in 2019. The spectral analysis resulted in the discovery of a cyclotron absorption feature in the source spectrum at ~48 keV both in the pulse phase averaged and resolved spectra. Accurate X-ray localization of the source using the NuSTAR and Chandra observatories allowed us to accurately determine the position of the X-ray source and identify the optical companion of the pulsar. The analysis of the counterpart properties suggested that the system is likely a symbiotic binary hosting an X-ray pulsar and a late type companion star of K-M classes rather than Be X-ray binary as previously suggested.Comment: 12 pages, 12 figures, accepted by Ap

    Folding of poly-amino acids and intrinsically disordered proteins in overcrowded milieu induced by pH change

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    pH-induced structural changes of the synthetic homopolypeptides poly-E, poly-K, poly-R, and intrinsically disordered proteins (IDPs) prothymosin alpha (ProT alpha) and linker histone H1, in concentrated PEG solutions simulating macromolecular crowding conditions within the membrane-less organelles, were characterized. The conformational transitions of the studied poly-amino acids in the concentrated PEG solutions depend on the polymerization degree of these homopolypeptides, the size of their side chains, the charge distribution of the side chains, and the crowding agent concentration. The results obtained for poly-amino acids are valid for IDPs having a significant total charge. The overcrowded conditions promote a significant increase in the cooperativity of the pH-induced coil-alpha-helix transition of ProTa and provoke histone H1 aggregation. The most favorable conditions for the pH-induced structural transitions in concentrated PEG solutions are realized when the charged residues are grouped in blocks, and when the distance between the end of the side group carrying charge and the backbone is small. Therefore, the block-wise distribution of charged residues within the IDPs not only plays an important role in the liquid-liquid phase transitions, but may also define the expressivity of structural transitions of these proteins in the overcrowded conditions of the membrane-less organelles. (C) 2018 Elsevier B.V. All rights reserved.Peer reviewe

    Broad-band analysis of X-ray pulsar 2S 1845–024

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    We present the results of a detailed investigation of the poorly studied X-ray pulsar 2S 1845−024 based on data obtained at the NuSTAR observatory during the type I outburst in 2017. Neither pulse phase-averaged nor phase-resolved spectra of the source show evidence for a cyclotron absorption feature. We also used data obtained from other X-ray observatories (Swift, XMM-Newton and Chandra) to study the spectral properties as a function of orbital phase. The analysis reveals a high hydrogen column density for the source reaching ∼1024 cm−2 around periastron. Using high-quality Chandra data we were able to obtain an accurate localization of 2S 1845−024 at 18h48m16s.8 and Dec. = −2◦25'25".1 (J2000), which allowed us to use infrared (IR) data to roughly classify the optical counterpart of the source as an OB supergiant at a distance of ≳15 kpc.</p
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