265 research outputs found

    The survivorship and water loss of Liometopum luctuosum (Hymenoptera: Formicidae) and Liometopum occidentale (Hymenoptera: Formicidae) exposed to different temperatures and relative humidity.

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    Two species of velvety tree ants, Liometopum luctuosum Wheeler, and Liometopum occidentale Emery (Hymenoptera: Formicidae), are commonly found in the western Unites States from Washington to southern California. L. luctuosum is restricted to coniferous forests in the mountains in the southern range, whereas L. occidentale is found in the lowlands. The survivorship of workers of both species exposed to several temperatures and relative humidity (RH) was determined. As temperature increased, survival of both species decreased. As the RH increased, survival of both species increased. However, L. luctuosum had higher overall survival in all treatment groups. The cuticular permeability (CP) and the rates of body water loss for each species were determined. Both species had similar CPs. Increased physiological tolerances of L. luctuosum may be an explanation for its broader distribution

    A Review of the Biology, Ecology and Behavior of Velvety Tree Ants of North America

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    Ants belonging to the genus Liometopum are regionally distributed across North America, Europe and Asia. L. apiculatum Mayr, L. luctuosum Wheeler, and L. occidentale Emery are found in western North America and are referred to as velvety tree ants. Very little is known about the biology of these species, but they are similar. They are typically associated with trees and shrubs and are frequently found tending hemipterans. All three species are are easily disturbed and and resort to highly aggressive behaviors including the use of strong alarm odors. The following review is intended to summarize the literature regarding the biology and control of these species. Special emphasis has been given to factors that might be important in their control and gaps in our current knowledge.</span

    Controlling the Cyanobacterial Clock by Synthetically Rewiring Metabolism

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    SummaryCircadian clocks are oscillatory systems that allow organisms to anticipate rhythmic changes in the environment. Several studies have shown that circadian clocks are connected to metabolism, but it is not generally clear whether metabolic signaling is one voice among many that influence the clock or whether metabolic cycling is the major clock synchronizer. To address this question in cyanobacteria, we used a synthetic biology approach to make normally autotrophic cells capable of growth on exogenous sugar. This allowed us to manipulate metabolism independently from light and dark. We found that feeding sugar to cultures blocked the clock-resetting effect of a dark pulse. Furthermore, in the absence of light, the clock efficiently synchronizes to metabolic cycles driven by rhythmic feeding. We conclude that metabolic activity, independent of its source, is the primary clock driver in cyanobacteria

    Susceptibility of adult cat fleas (Siphonaptera: Pulicidae) to insecticides and status of insecticide resistance mutations at the Rdl and knockdown resistance loci

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    This is an Open Access article. © 2015 The Author(s). Published by Springer Berlin Heidelberg.The susceptibility of 12 field-collected isolates and 4 laboratory strains of cat fleas, Ctenocephalides felis was determined by topical application of some of the insecticides used as on-animal therapies to control them. In the tested field-collected flea isolates the LD50 values for fipronil and imidacloprid ranged from 0.09 to 0.35 ng/flea and 0.02 to 0.19 ng/flea, respectively, and were consistent with baseline figures published previously. The extent of variation in response to four pyrethroid insecticides differed between compounds with the LD50 values for deltamethrin ranging from 2.3 to 28.2 ng/flea, etofenprox ranging from 26.7 to 86.7 ng/flea, permethrin ranging from 17.5 to 85.6 ng/flea, and d-phenothrin ranging from 14.5 to 130 ng/flea. A comparison with earlier data for permethrin and deltamethrin implied a level of pyrethroid resistance in all isolates and strains. LD50 values for tetrachlorvinphos ranged from 20.0 to 420.0 ng/flea. The rdl mutation (conferring target-site resistance to cyclodiene insecticides) was present in most field-collected and laboratory strains, but had no discernible effect on responses to fipronil, which acts on the same receptor protein as cyclodienes. The kdr and skdr mutations conferring target-site resistance to pyrethroids but segregated in opposition to one another, precluding the formation of genotypes homozygous for both mutations.Peer reviewedFinal Published versio

    Nogo-A is secreted in extracellular vesicles, occurs in blood and can influence vascular permeability

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    Nogo-A is a transmembrane protein with multiple functions in the central nervous system (CNS), including restriction of neurite growth and synaptic plasticity. Thus far, Nogo-A has been predominantly considered a cell contact-dependent ligand signaling via cell surface receptors. Here, we show that Nogo-A can be secreted by cultured cells of neuronal and glial origin in association with extracellular vesicles (EVs). Neuron- and oligodendrocyte-derived Nogo-A containing EVs inhibited fibroblast spreading, and this effect was partially reversed by Nogo-A receptor S1PR2 blockage. EVs purified from HEK cells only inhibited fibroblast spreading upon Nogo-A over-expression. Nogo-A-containing EVs were found in vivo in the blood of healthy mice and rats, as well as in human plasma. Blood Nogo-A concentrations were elevated after acute stroke lesions in mice and rats. Nogo-A active peptides decreased barrier integrity in an in vitro blood-brain barrier model. Stroked mice showed increased dye permeability in peripheral organs when tested 2 weeks after injury. In the Miles assay, an in vivo test to assess leakage of the skin vasculature, a Nogo-A active peptide increased dye permeability. These findings suggest that blood borne, possibly EV-associated Nogo-A could exert long-range regulatory actions on vascular permeability

    A study of the effectiveness of a detergent-based California mastitis test (CMT), using Ethiopian and Nigerian domestic detergents, for the detection of high somatic cell counts in milk and their reliability compared to the commercial UK CMT [version 2; peer review: 2 approved]

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    Background:  The California mastitis test (CMT) is a simple cow-side indicator of the somatic cell count (SCC) in milk, providing a useful tool in identifying cases of subclinical mastitis in cattle. Mastitis, and in particular subclinical mastitis, is a major concern in Ethiopia and Nigeria, yet detection is challenging due to cost and access to commercial CMT reagents. Methods: Commercially available domestic detergents from Ethiopia and Nigeria were compared (n = 3 for each country) with the UK commercial CMT reagent in their ability to detect high SCC (>400,000 cells/ml milk).  Sensitivity and specificity of the CMT test were calculated for the different detergents and positive and negative predictive values were established. Results:  The average sensitivities of the tests ranged from 28-75% for the Ethiopian detergents and 68-80% for the Nigerian detergents, compared to 76% for the UK domestic detergent.  Test specificities were 84-98%, 93-97% and 96%, respectively. Conclusions:  Overall, the detergents demonstrated higher specificity than sensitivity.  Nigerian detergents performed better than the Ethiopian products, however, the study identified suitable domestic detergents from both Ethiopia and Nigeria, comparable to the UK commercial CMT reagent, and we recommend their use as alternative CMT reagents for livestock-keepers to aid in cost-effective diagnosis of mastitis

    Bose-Einstein Correlations of Three Charged Pions in Hadronic Z^0 Decays

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    Bose-Einstein Correlations (BEC) of three identical charged pions were studied in 4 x 10^6 hadronic Z^0 decays recorded with the OPAL detector at LEP. The genuine three-pion correlations, corrected for the Coulomb effect, were separated from the known two-pion correlations by a new subtraction procedure. A significant genuine three-pion BEC enhancement near threshold was observed having an emitter source radius of r_3 = 0.580 +/- 0.004 (stat.) +/- 0.029 (syst.) fm and a strength of \lambda_3 = 0.504 +/- 0.010 (stat.) +/- 0.041 (syst.). The Coulomb correction was found to increase the \lambda_3 value by \~9% and to reduce r_3 by ~6%. The measured \lambda_3 corresponds to a value of 0.707 +/- 0.014 (stat.) +/- 0.078 (syst.) when one takes into account the three-pion sample purity. A relation between the two-pion and the three-pion source parameters is discussed.Comment: 19 pages, LaTeX, 5 eps figures included, accepted by Eur. Phys. J.
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