26 research outputs found

    Land Grant Application- Carvell, Henry (Lewiston)

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    Land grant application submitted to the Maine Land Office on behalf of Henry Carvell for service in the Revolutionary War, by their widow Mercy.https://digitalmaine.com/revolutionary_war_me_land_office/1164/thumbnail.jp

    Genomic identification of cryptic susceptibility to penicillins and β-lactamase inhibitors in methicillin-resistant Staphylococcus aureus.

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    Antibiotic resistance in bacterial pathogens threatens the future of modern medicine. One such resistant pathogen is methicillin-resistant Staphylococcus aureus (MRSA), which is resistant to nearly all β-lactam antibiotics, limiting treatment options. Here, we show that a significant proportion of MRSA isolates from different lineages, including the epidemic USA300 lineage, are susceptible to penicillins when used in combination with β-lactamase inhibitors such as clavulanic acid. Susceptibility is mediated by a combination of two different mutations in the mecA promoter region that lowers mecA-encoded penicillin-binding protein 2a (PBP2a) expression, and in the majority of isolates by either one of two substitutions in PBP2a (E246G or M122I) that increase the affinity of PBP2a for penicillin in the presence of clavulanic acid. Treatment of S. aureus infections in wax moth and mouse models shows that penicillin/β-lactamase inhibitor susceptibility can be exploited as an effective therapeutic choice for 'susceptible' MRSA infection. Finally, we show that isolates with the PBP2a E246G substitution have a growth advantage in the presence of penicillin but the absence of clavulanic acid, which suggests that penicillin/β-lactamase susceptibility is an example of collateral sensitivity (resistance to one antibiotic increases sensitivity to another). Our findings suggest that widely available and currently disregarded antibiotics could be effective in a significant proportion of MRSA infections.MRC - G1001787/1 MRC - MR/N002660/1 WT098600 HICF-T5-342 MR/S00291X/1 201344/Z/16/Z MR/P007201/

    Field realistic doses of pesticide imidacloprid reduce bumblebee pollen foraging efficiency

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    Bumblebees and other pollinators provide a vital ecosystem service for the agricultural sector. Recent studies however have suggested that exposure to systemic neonicotinoid insecticides in flowering crops has sub-lethal effects on the bumblebee workforce, and hence in reducing queen production. The mechanism behind reduced nest performance, however, remains unclear. Here we use Radio Frequency Identification (RFID) technology to test whether exposure to a low, field realistic dose (0.7 ppb in sugar water and 6 ppb in pollen) of the neonicotinoid imidacloprid, reduces worker foraging efficiency. Whilst the nectar foraging efficiency of bees treated with imidacloprid was not significantly different than that of control bees, treated bees brought back pollen less often than control bees (40 % of trips vs 63 % trips, respectively) and, where pollen was collected, treated bees brought back 31 % less pollen per hour than controls. This study demonstrates that field-realistic doses of these pesticides substantially impacts on foraging ability of bumblebee workers when collecting pollen, and we suggest that this provides a causal mechanism behind reduced queen production in imidacloprid exposed colonies

    Assessing the resilience of biodiversity-driven functions in agroecosystems under environmental change

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    Weeds for bees? A review

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    Land Grant Application- Carvell, Henry (Lewiston)

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    Land grant application submitted to the Maine Land Office on behalf of Henry Carvell for service in the Revolutionary War, by their widow Mercy.https://digitalmaine.com/revolutionary_war_me_land_office/1164/thumbnail.jp

    Homotypic cell contact enhances insulin but not glucagon secretion

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    Intra-islet interactions influence β-cell function, and disruption of islet architecture results in a reduction in glucose-induced insulin secretion, whereas re-aggregation improves secretory responsiveness. Our studies on MIN6 cells have shown that by configuring β-cells as three-dimensional islet-like structures there is a marked improvement in glucose-induced insulin secretion compared to that of their monolayer equivalents. In the present study, we have used the mouse glucagon-secreting αTC1 cell line to see whether homotypic interactions are important in the regulation of glucagon secretion from α-cells. We found no significant difference in the secretory responses of αTC1 cells maintained as monolayers or as cell clusters. We also found that different cell adhesion molecules are involved in cell interactions between α- and β-cells; MIN6 cells express ECAD, whereas αTC1 cells express NCAM. ECAD is necessary for cell cluster formation by MIN6 cells but not by αTC1 cells, whereas NCAM is not needed for the formation of cell clusters in either cell line
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