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"Martin, Stephen"
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A survey of UK beekeeper’s Varroa treatment habits
The global spread of the parasitic mite Varroa destructor instigated a substantial decline in both managed and feral honeybee ( Apis mellifera) colonies mainly across the Northern hemisphere. In response, many beekeepers began to treat their colonies with chemical acaricides to control mite populations in managed colonies. However, some countries or beekeepers allowed their bees to develop mite-resistance by adopting a “treatment-free” approach, rather than using selective breeding programs. Yet, the distribution and proportion of beekeepers either treating or not within the United Kingdom (UK) is unknown, as it is in most Northern hemisphere countries. Therefore, the aim of this study was to conduct a beekeeper survey to determine the current treatment strategies within the UK. We gathered 2,872 beekeeper responses from an estimated 30,000 UK beekeepers belonging to 242 bee-associations in the winter of 2020/21. The survey indicated that the majority (72–79%) of UK beekeepers are still treating their bees for Varroa , typically twice-yearly using chemical-based methods. Six percent or 1,800 UK beekeepers were treatment-free for six years or more. This is reflected by our finding that 78 associations out of 242 consist of responders who entirely treated, while only four associations had more than 75% of their members that were non-treating. Overall treatment status was not affected by association currently. Using the baseline data from this survey it will be possible in the future to observer if a shift towards treatment-free beekeeping occurs or not.
Journal Article
Receptor binding and priming of the spike protein of SARS-CoV-2 for membrane fusion
Infection with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is initiated by virus binding to the ACE2 cell-surface receptors
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, followed by fusion of the virus and cell membranes to release the virus genome into the cell. Both receptor binding and membrane fusion activities are mediated by the virus spike glycoprotein
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. As with other class-I membrane-fusion proteins, the spike protein is post-translationally cleaved, in this case by furin, into the S1 and S2 components that remain associated after cleavage
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. Fusion activation after receptor binding is proposed to involve the exposure of a second proteolytic site (S2′), cleavage of which is required for the release of the fusion peptide
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. Here we analyse the binding of ACE2 to the furin-cleaved form of the SARS-CoV-2 spike protein using cryo-electron microscopy. We classify ten different molecular species, including the unbound, closed spike trimer, the fully open ACE2-bound trimer and dissociated monomeric S1 bound to ACE2. The ten structures describe ACE2-binding events that destabilize the spike trimer, progressively opening up, and out, the individual S1 components. The opening process reduces S1 contacts and unshields the trimeric S2 core, priming the protein for fusion activation and dissociation of ACE2-bound S1 monomers. The structures also reveal refolding of an S1 subdomain after ACE2 binding that disrupts interactions with S2, which involves Asp614
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and leads to the destabilization of the structure of S2 proximal to the secondary (S2′) cleavage site.
Cryo-electron microscopy structures of consecutive binding events of ACE2 in complex with the spike protein of SARS-CoV-2 reveal the mechanisms of receptor binding by the spike protein and activation for membrane fusion by the spike protein of SARS-CoV-2.
Journal Article
Evidence-based horsemanship
Most horsemen agree that timing, feel, and balance are the holy trinity of horsemanship. The balance is brilliant: scientific facts and the empirical evidence to support those facts assembled by two highly respected professionals in their respective disciplines.
BOOK
Sacrificing patient care for prevention: distortion of the role of general practice
Expansion of preventive clinical recommendations in primary care has had the unintended consequence of destabilising this foundation of the healthcare system, argue Minna Johansson and colleagues
Journal Article
SARS-CoV-2 and bat RaTG13 spike glycoprotein structures inform on virus evolution and furin-cleavage effects
SARS-CoV-2 is thought to have emerged from bats, possibly via a secondary host. Here, we investigate the relationship of spike (S) glycoprotein from SARS-CoV-2 with the S protein of a closely related bat virus, RaTG13. We determined cryo-EM structures for RaTG13 S and for both furin-cleaved and uncleaved SARS-CoV-2 S; we compared these with recently reported structures for uncleaved SARS-CoV-2 S. We also biochemically characterized their relative stabilities and affinities for the SARS-CoV-2 receptor ACE2. Although the overall structures of human and bat virus S proteins are similar, there are key differences in their properties, including a more stable precleavage form of human S and about 1,000-fold tighter binding of SARS-CoV-2 to human receptor. These observations suggest that cleavage at the furin-cleavage site decreases the overall stability of SARS-CoV-2 S and facilitates the adoption of the open conformation that is required for S to bind to the ACE2 receptor.Cryo-EM and functional analyses of furin-cleaved spike from SARS-CoV-2 and the closely related spike from bat virus RaTG13 reveal differences in protein stability and binding to human receptor ACE2.
Journal Article