2,218 research outputs found

    RNAseq of Deformed wing virus and other honey bee-associated viruses in eight insect taxa with or without Varroa infestation

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    The global spread of a parasitic mite (Varroa destructor) has resulted in Deformed wing virus (DWV), a previously rare pathogen, now dominating the viromes in honey bees and contributing to large-scale honey bee colony losses. DWV can be found in diverse insect taxa and has been implicated in spilling over from honey bees into associated (“apiary”) and other (“non-apiary”) insects. Here we generated next generation sequence data from 127 insect samples belonging to diverse taxa collected from Hawaiian islands with and without Varroa to identify whether the mite has indirectly affected the viral landscapes of key insect taxa across bees, wasps, flies and ants. Our data showed that, while Varroa was associated with a dramatic increase in abundance of (predominantly recombinant) DWV in honey bees (and no other honey bee-associated RNA virus), this change was not seen in any other taxa sampled. Honey bees share their environment with other insect populations and exist as a homogenous group, frequently sharing common viruses, albeit at low levels. Our data suggest that the threat of Varroa to increase viral load in an apiary does not automatically translate to an increase in virus load in other insects living in the wider community

    Deformed wing virus variant shift from 2010 to 2016 in managed and feral UK honey bee colonies

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    Deformed wing virus (DWV) has been linked to the global decline of honey bees. DWV exists as three master variants (DWV-A, DWV-B, and DWV-C), each with differing outcomes for the honey bee host. Research in the USA showed a shift from DWV-A to DWV-B between 2010 to 2016 in honey bee colonies. Likewise, in the UK, a small study in 2007 found only DWV-A, whereas in 2016, DWV-B was the most prevalent variant. This suggests a shift from DWV-A to DWV-B might have occurred in the UK between 2007 and 2016. To investigate this further, data from samples collected in 2009/10 (n = 46) were compared to existing data from 2016 (n = 42). These samples also allowed a comparison of DWV variants between Varroa-untreated (feral) and Varroa-treated (managed) colonies. The results revealed that, in the UK, DWV-A was far more prevalent in 2009/10 (87%) than in 2016 (43%). In contrast, DWV-B was less prevalent in 2009/10 (76%) than in 2016 (93%). Regardless if colonies had been treated for Varroa (managed) or not (feral), the same trend from DWV-A to DWV-B occurred. Overall, the results reveal a decrease in DWV-A and an increase in DWV-B in UK colonies

    Molecular and phylogenetic analysis reveals new diversity of Dunaliella salina from hypersaline environments.

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    Twelve hyper-β carotene-producing strains of algae assigned to the genus Dunaliella salina have been isolated from various hypersaline environments in Israel, South Africa, Namibia and Spain. Intron-sizing of the SSU rDNA and phylogenetic analysis of these isolates were undertaken using four commonly employed markers for genotyping, LSU rDNA, ITS, rbcL and tufA and their application to the study of Dunaliella evaluated. Novel isolates have been identified and phylogenetic analyses have shown the need for clarification on the taxonomy of Dunaliella salina. We propose the division of D. salina into four sub-clades as defined by a robust phylogeny based on the concatenation of four genes. This study further demonstrates the considerable genetic diversity within D. salina and the potential of genetic analyses for aiding in the selection of prospective economically important strains

    The Legionella pneumophila Dot/Icm type IV secretion system and its effectors

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    To prevail in the interaction with eukaryotic hosts, many bacterial pathogens use protein secretion systems to release virulence factors at the host–pathogen interface and/or deliver them directly into host cells. An outstanding example of the complexity and sophistication of secretion systems and the diversity of their protein substrates, effectors, is the Defective in organelle trafficking/Intracellular multiplication (Dot/Icm) Type IVB secretion system (T4BSS) of Legionella pneumophila and related species. Legionella species are facultative intracellular pathogens of environmental protozoa and opportunistic human respiratory pathogens. The Dot/Icm T4BSS translocates an exceptionally large number of effectors, more than 300 per L. pneumophila strain, and is essential for evasion of phagolysosomal degradation and exploitation of protozoa and human macrophages as replicative niches. Recent technological advancements in the imaging of large protein complexes have provided new insight into the architecture of the T4BSS and allowed us to propose models for the transport mechanism. At the same time, significant progress has been made in assigning functions to about a third of L. pneumophila effectors, discovering unprecedented new enzymatic activities and concepts of host subversion. In this review, we describe the current knowledge of the workings of the Dot/Icm T4BSS machinery and provide an overview of the activities and functions of the to-date characterized effectors in the interaction of L. pneumophila with host cells

    Phaeoviruses discovered in kelp (Laminariales)

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    Phaeoviruses are latent double-stranded DNA viruses that insert their genomes into those of their brown algal (Phaeophyceae) hosts. So far these viruses are known only from members of the Ectocarpales, which are small and short-lived macroalgae. Here we report molecular and morphological evidence for a new Phaeovirus cluster, referred to as sub-group C, infecting kelps (Laminariales) of the genera Laminaria and Saccharina, which are ecologically and commercially important seaweeds. Epifluorescence and TEM observations indicate that the Laminaria digitata Virus (LdigV), the type species of sub-group C, targets the host nucleus for its genome replication, followed by gradual degradation of the chloroplast and assembly of virions in the cytoplasm of both vegetative and reproductive cells. This study is the first to describe phaeoviruses in kelp. In the field, these viruses infected two thirds of their host populations; however, their biological impact remains unknown

    Ten years of Deformed Wing Virus (DWV) in Hawaiian honey bees (Apis mellifera), the dominant DWV-A variant is potentially being replaced by variants with a DWV-B coding sequence

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    The combination of Deformed wing virus (DWV) and Varroa destructor is arguably one of the greatest threats currently facing western honey bees, Apis mellifera. Varroa’s association with DWV has decreased viral diversity and increased loads of DWV within honey bee populations. Nowhere has this been better studied than in Hawaii, where the arrival of Varroa progressively led to the dominance of the single master variant (DWV-A) on both mite-infested Hawaiian Islands of Oahu and Big Island. Now, exactly 10 years following the original study, we find that the DWV population has changed once again, with variants containing the RdRp coding sequence pertaining to the master variant B beginning to co-dominate alongside variants with the DWV-A RdRp sequence on the mite-infested islands of Oahu and Big Island. In speculation, based on other studies, it appears this could represent a stage in the journey towards the complete dominance of DWV-B, a variant that appears better adapted to be transmitted within honey bee colonies

    A novel evolutionary strategy revealed in the Phaeoviruses

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    Phaeoviruses infect the brown algae, which are major contributors to primary production of coastal waters and estuaries. They exploit a Persistent evolutionary strategy akin to a K- selected life strategy via genome integration and are the only known representatives to do so within the giant algal viruses that are typified by r- selected Acute lytic viruses. In screening the genomes of five species within the filamentous brown algal lineage, here we show an unprecedented diversity of viral gene sequence variants especially amongst the smaller phaeoviral genomes. Moreover, one variant shares features from both the two major sub-groups within the phaeoviruses. These phaeoviruses have exploited the reduction of their giant dsDNA genomes and accompanying loss of DNA proofreading capability, typical of an Acute life strategist, but uniquely retain a Persistent life strategy

    Changes in Magnetization and in Dislocation Arrangements in Cyclically Deformed Iron and Nickel

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    There are a lot of experimental results concerning the effect of stress, elastic and plastic deformation and dislocation structure on the magnetic properties of ferromagnetic material. Atherton et al. measured stress induced changes in the magnetization of steel pipesl. Schroeder et al. studied domain arrangement in plastically deformed iron single crystals2. Hayashi et al. found that the application of an oscillating magnetic field during tensile testing reduced the flow stress of nickel3. Jiles and Atherton4,5D reported changes in magnetization during one stress cycle as a function of an external magnetic field. They have also reported a theory that describes ferromagnetic hysteresis and the effect of stress on magnetization. This theory is based on the Langevins theory of paramagnetism. Jiles and Atherton4 have experimentally shown that the modified Langevins equation gives the change in magnetization as a function of the applied magnetic field

    Determination of H-Atom Positions in Organic Crystal Structures by NEXAFS Combined with Density Functional Theory: a Study of Two-Component Systems Containing Isonicotinamide

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    It is important to be able to identify the precise position of H-atoms in hydrogen bonding interactions to fully understand the effects on the structure and properties of organic crystals. Using a combination of near-edge X-ray absorption fine structure (NEXAFS) spectroscopy and density functional theory (DFT) quantum chemistry calculations, we demonstrate the sensitivity of core-level X-ray spectroscopy to the precise H-atom position within a donor-proton-acceptor system. Exploiting this sensitivity, we then combine the predictive power of DFT with the experimental NEXAFS, confirming the H-atom position identified using single-crystal X-ray diffraction (XRD) techniques more easily than using other H-atom sensitive techniques, such as neutron diffraction. This proof of principle experiment confirms the H-atom positions in structures obtained from XRD, providing evidence for the potential use of NEXAFS as a more accurate and easier method of locating H-atoms within organic crystals

    Dual-functioning transcription factors in the developmental gene network of Drosophila melanogaster

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    Quantitative models for transcriptional regulation have shown great promise for advancing our understanding of the biological mechanisms underlying gene regulation. However, all of the models to date assume a transcription factor (TF) to have either activating or repressing function towards all the genes it is regulating.In this paper we demonstrate, on the example of the developmental gene network in D. melanogaster, that the data-fit can be improved by up to 40% if the model is allowing certain TFs to have dual function, that is, acting as activator for some genes and as repressor for others. We demonstrate that the improvement is not due to additional flexibility in the model but rather derived from the data itself. We also found no evidence for the involvement of other known site-specific TFs in regulating this network. Finally, we propose SUMOylation as a candidate biological mechanism allowing TFs to switch their role when a small ubiquitin-like modifier (SUMO) is covalently attached to the TF. We strengthen this hypothesis by demonstrating that the TFs predicted to have dual function also contain the known SUMO consensus motif, while TFs predicted to have only one role lack this motif.We argue that a SUMOylation-dependent mechanism allowing TFs to have dual function represents a promising area for further research and might be another step towards uncovering the biological mechanisms underlying transcriptional regulation
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