324 research outputs found

    Occurrence of double-stranded RNA species in champignon and their relation to Mushroom Virus X symptoms

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    Mycoviruses are known to infect fungi of different habitats and life style. Some of them, like the Mushroom Virus X (MVX) complex, cause abnormal development of fruiting bodies and severe yield losses in mushroom cultivation. Most mycoviruses have a double-stranded RNA (dsRNA) genome, therefore dsRNA-detection is frequently used as a first step to identify virus infection. In relation with MVX 23 dsRNAs species have been described, occurring in variable number and combination in diseased mushrooms. The aim of our experiments was to find out whether dsRNA-immunoblotting can be used to detect dsRNA in small samples of cultivated A. bisporus varieties and of wild growing Agaricus species. We found that by immunoblotting, the same dsRNA species were detected in apparently healthy cultivated champignon fruiting bodies and in MVX-infected reference samples, respectively, as by conventional CF11 chromatography, but for immunoblotting a much smaller sample size was needed. In two out of three deformed fruit bodies of cultivated A. bisporus from Hungary we detected a 4.1 kbp dsRNA species which was also present in the MVX infected reference samples. Diverse and variable dsRNA patterns were observed in apparently healthy samples of 12 wild growing Agaricus species, indicating that extreme care should be taken when non-cultivated Agaricus is used for breeding new varieties. Non-sterile cultures and environmental mushroom specimens are fairly often mixed with parasitic and endofungal organisms, therefore, we also tested fungi isolated from mushroom cultures. Here again, 1–7 dsRNA species were found in extracts of Trichoderma and Dactylium isolates and of Mycogone-infected sporophores. Our results demonstrate clearly that dsRNAs from very different origins can be present in cultivated champignon and support the view that the MVX symptom-associated dsRNAs are probably of polyphyletic origin and do not represent one defined virus

    Preliminary notes on dual relevance of ITS sequences and pigments in Hygrocybe taxonomy

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    The relationships based on ITS sequences of 48 Hygrocybe s.l. specimens were studied and compared with previously described taxonomic groups. Our specimens formed two well separated genetic groups. The first one includes the species characterized by vivid yellow and red colours, while species belonging to other clades were pallid or pale brown, and in most cases with pink or olive tones. This separation is supported by the presence of muscaflavin pigments among some species referred to Hygrocybe (Bresinsky & Kronawitter 1986). The subgenera distinguished by morphological features can be relatively well recognized on phylogenetic trees, however, the majority of sections were not supported. Variability in the ITS region of Hygrocybe species is unusually high. In some cases sequences differed by more than 25 %, and the lengths of ITS regions also showed large differences. Taxa that were considered as closely related, e.g. the H. conica aggregate, were found to have identical or highly similar sequences. Our results seem to confirm the taxonomic concept of Bresinsky (2008) who proposed the division of the genus Hygrocybe. Hence H. calyptriformis and all examined members of subg. Gliophorus (H. irrigata, H. laeta, H. nitrata, H. psittacina) and subg. Cuphophyllus could be excluded from the genus Hygrocybe s.str. Based on these results further research using DNA markers at the intergeneric level is suggested to revaluate the taxonomy of former Hygrocybe species

    Supra-oscillatory critical temperature dependence of Nb-Ho bilayers

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    We investigate the critical temperature Tc of a thin s-wave superconductor (Nb) proximity coupled to a helical rare earth ferromagnet (Ho). As a function of the Ho layer thickness, we observe multiple oscillations of Tc superimposed on a slow decay, that we attribute to the influence of the Ho on the Nb proximity effect. Because of Ho inhomogeneous magnetization, singlet and triplet pair correlations are present in the bilayers. We take both into consideration when solving the self consistent Bogoliubov-de Gennes equations, and we observe a reasonable agreement. We also observe non-trivial transitions into the superconducting state, the zero resistance state being attained after two successive transitions which appear to be associated with the magnetic structure of Ho.Comment: Main article: 5 pages, 4 figures; Supplementary materials: 4 pages, 5 figure

    Higher order corrections for shallow-water solitary waves: elementary derivation and experiments

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    We present an elementary method to obtain the equations of the shallow-water solitary waves in different orders of approximation. The first two of these equations are solved to get the shapes and propagation velocities of the corresponding solitary waves. The first-order equation is shown to be equivalent to the Korteweg-de Vries (KdV) equation, while the second-order equation is solved numerically. The propagation velocity found for the solitary waves of the second-order equation coincides with a known expression, but it is obtained in a simpler way. By measuring the propagation velocity of solitary waves in the laboratory, we demonstrate that the second-order theory gives a considerably improved fit to experimental results.Comment: 15 pages, 8 EPS figures, uses IOP class file for LaTeX2e, slightly revised versio

    Seed collection data encompassing half of the vascular flora of the pannonian ecoregion stored by the pannon seed bank

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    Seed bank collections have multiple benefits: store genetic material for conservation and research, and their data can also provide valuable scientific information. The Pannon Seed Bank was established during an EU LIFE+ project between 2010 and 2014 with the target to collect and store seeds of approx. 50% of the wild native vascular flora of the Pannonian Biogeographic Region, seed accessions of at least 800 storable species. This task was fully achieved by the end of the project, as altogether 1,853 seed accessions of 910 species are stored. The aim of the present paper is to provide access to the collection data and metadata of the Pannon Seed Bank as it was completed by the end of the project. The collection campaign involved about 40 experts and covered the whole country. Collection and storing applied standard methodology, based on the ENSCONET project. The collection data published in this paper can be used manifold. Geographical data on species occurrences are major input for nature conservation and research. Seed collection date is valuable for ecological studies of phytophagous insects, frugivorous birds and mammals, etc. The database can be partner to international databases (like GBIF) or research infrastructures (e.g. LifeWatch). Hopefully, this data paper will contribute to further motivate the development of native seed collections and their use for conservation and research in Hungary. © 2016 Akadémiai Kiadó, Budapest

    Evolutionary Genomics of Genes Involved in Olfactory Behavior in the Drosophila melanogaster Species Group

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    Previous comparative genomic studies of genes involved in olfactory behavior in Drosophila focused only on particular gene families such as odorant receptor and/or odorant binding proteins. However, olfactory behavior has a complex genetic architecture that is orchestrated by many interacting genes. In this paper, we present a comparative genomic study of olfactory behavior in Drosophila including an extended set of genes known to affect olfactory behavior. We took advantage of the recent burst of whole genome sequences and the development of powerful statistical tools to analyze genomic data and test evolutionary and functional hypotheses of olfactory genes in the six species of the Drosophila melanogaster species group for which whole genome sequences are available. Our study reveals widespread purifying selection and limited incidence of positive selection on olfactory genes. We show that the pace of evolution of olfactory genes is mostly independent of the life cycle stage, and of the number of life cycle stages, in which they participate in olfaction. However, we detected a relationship between evolutionary rates and the position that the gene products occupy in the olfactory system, genes occupying central positions tend to be more constrained than peripheral genes. Finally, we demonstrate that specialization to one host does not seem to be associated with bursts of adaptive evolution in olfactory genes in D. sechellia and D. erecta, the two specialists species analyzed, but rather different lineages have idiosyncratic evolutionary histories in which both historical and ecological factors have been involved

    Photon Rates for Heavy-Ion Collisions from Hidden Local Symmetry

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    We study photon production from the hidden local symmetry approach that includes pions, rho and a1 mesons and compute the corresponding photon emission rates from a hadronic gas in thermal equilibrium. Together with experimental radiative decay widths of the background, these rates are used in a relativistic transport model to calculate single photon spectra in heavy-ion collisions at SPS energies. We then employ this effective theory to test three scenarios for the chiral phase transition in high-temperature nuclear matter including decreasing vector meson masses. Although all calculations respect the upper bound set by the WA80 Collaboration, we find the scenarios could be distinguished with more detailed data.Comment: 12 pages, 12 Postscript figures; discussion of thermal equilibrium rates expanded, minor corrections to text and graph
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