3,421 research outputs found

    Mechanisms underlying the endothelium-dependent vasodilatory effect of an aqueous extract of Elaeis guineensis Jacq. (Arecaceae) in porcine coronary artery rings

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    This study was undertaken to investigate the vasodilatory effect of an aqueous extract of Elaeis guineensis Jacq (EGE) in the porcine coronary artery and elicit its possible mechanism(s) of action. Vascular effects of crude extract of dried and powdered leaves of Elaeis guineensis were evaluated on isolated coronary arteries on organ chambers. Determination of eNOS expression and the phosphorylation level of eNOS were  determined by Western blot analysis. In the presence of indomethacin,  EGE caused pronounced relaxations in endothelium-intact but not in endothelium-denuded coronary artery rings. Relaxations to EGE were significantly reduced by Nω-nitro-L-arginine (L-NA, a competitive inhibitor of NO synthase), slightly but not significantly by charybdotoxin plus apamin (two potent inhibitors of EDHF-mediated responses) and abolished by the combination of L-NA and charybdotoxin plus apamin. Relaxations to EGE were abolished by the membrane permeant, SOD mimetic, MnTMPyP, and significantly reduced by wortmannin, an inhibitor of PI3-kinase. Exposure of endothelial cells to EGE increased the phosphorylation level of eNOS at Ser1177 in a time and concentration-dependent manner. MnTMPyP abolished the EGE-induced phosphorylation of eNOS. In conclusion, the obtained data indicate that EGE induces pronounced endothelium-dependent relaxations of the porcine coronary artery, which involve predominantly NO. The stimulatory effect of EGE on eNOS involves the redox-sensitive phosphorylation of eNOS at Ser1177 most likely via the PI3-kinase pathway

    Coprophagous features in carnivorous Nepenthes plants: a task for ureases

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    Most terrestrial carnivorous plants are specialized on insect prey digestion to obtain additional nutrients. Few species of the genus Nepenthes developed mutualistic relationships with mammals for nitrogen supplementation. Whether dietary changes require certain enzymatic composition to utilize new sources of nutrients has rarely been tested. Here, we investigated the role of urease for Nepenthes hemsleyana that gains nitrogen from the bat Kerivoula hardwickii while it roosts inside the pitchers. We hypothesized that N. hemsleyana is able to use urea from the bats’ excrements. In fact, we demonstrate that 15N-enriched urea provided to Nepenthes pitchers is metabolized and its nitrogen is distributed within the plant. As ureases are necessary to degrade urea, these hydrolytic enzymes should be involved. We proved the presence and enzymatic activity of a urease for Nepenthes plant tissues. The corresponding urease cDNA from N. hemsleyana was isolated and functionally expressed. A comprehensive phylogenetic analysis for eukaryotic ureases, including Nepenthes and five other carnivorous plants’ taxa, identified them as canonical ureases and reflects the plant phylogeny. Hence, this study reveals ureases as an emblematic example for an efficient, low-cost but high adaptive plasticity in plants while developing a further specialized lifestyle from carnivory to coprophagy

    Communally breeding bats use physiological and behavioural adjustments to optimise daily energy expenditure

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    Small endotherms must change roosting and thermoregulatory behaviour in response to changes in ambient conditions if they are to achieve positive energy balance. In social species, for example many bats, energy expenditure is influenced by environmental conditions, such as ambient temperature, and also by social thermoregulation. Direct measurements of daily fluctuations in metabolic rates in response to ambient and behavioural variables in the field have not been technologically feasible until recently. During different reproductive periods, we investigated the relationships between ambient temperature, group size and energy expenditure in wild maternity colonies of Bechstein’s bats (Myotis bechsteinii). Bats used behavioural and physiological adjustments to regulate energy expenditure. Whether bats maintained normothermia or used torpor, the number of bats in the roosts as well changed with reproductive status and ambient temperature. During pregnancy and lactation, bats remained mostly normothermic and daily group sizes were relatively large, presumably to participate in the energetic benefits of social thermoregulation. In contrast, smaller groups were formed on days when bats used torpor, which occurred mostly during the post-lactation period. Thus, we were able to demonstrate on wild animals under natural conditions the significance of behavioural and physiological flexibility for optimal thermoregulatory behaviour in small endotherms

    Descriptive Beef Flavor Attributes and Consumer Acceptance Relationships for Heavy Beef Eaters

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    Differences in beef flavor attributes were created using beef cuts (Choice M. gluteus medius (GM) steaks; Choice M. biceps femoris (BF) roasts; Select BF roasts; Choice M. longissimus lumborum (LM) steaks, and high pH LM steaks), cooking method, and internal cook temperature endpoint (END). Steaks were cooked to 58°C and 80°C END utilizing either a George Foreman clamshell grill (GF) or a flat top electric food-service grill (GRILL). Roasts were cooked at low temperatures using a Crock-Pot (CP) cooking to 58°C and 80°C END. Thirty-seven flavor descriptive attributes were evaluated by an expert, trained descriptive beef flavor panel. Heavy beef eaters were recruited in Houston, TX; Olathe, KS; Philadelphia, PA; and Portland, OR. Consumers evaluated overall, flavor, beef flavor, and grill flavor liking using 9-point hedonic scales and beef flavor, grill flavor and off-flavor intensity using 9-point intensity scales. Steaks and roasts differed in descriptive and consumer attributes (P < 0.05). Treatments with higher levels of fat-like, salt, beef identity, and brown/roasted flavor attributes had higher consumer liking ratings (Choice LM or GM GRILL steaks cooked to 58°C or 80°C and Choice GM GRILL steaks cooked to 80°C). Select and Choice BF CP roasts cooked to 58°C or 80°C, Choice GM GF steaks cooked to 80°C, and high pH LM GF steaks cooked to 80°C had the lowest consumer liking scores and higher levels of warmed-over flavor, cardboardy, and liver-like flavor attributes. Heavy beef consumers segmented into 4 classes. Class 4 consumers liked beef regardless of treatment, whereas Class 3 consumers were discerning. Heavy beef eaters discerned differences in beef flavor attributes, and beef flavor was a driver of consumer liking

    Graph easy sets of mute lambda terms

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    Among the unsolvable terms of the lambda calculus, the mute ones are those having the highest degree of undefinedness. In this paper, we define for each natural number n, an infinite and recursive set M-n of mute terms, and show that it is graph-easy: for any closed term t of the lambda calculus there exists a graph model equating all the terms of M-n to t. Alongside, we provide a brief survey of the notion of undefinedness in the lambda calculus. (C) 2015 Elsevier B.V. All rights reserved

    Sympatric woodland Myotis bats form tight-knit social groups with exclusive roost home ranges

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    Background: The structuring of wild animal populations can influence population dynamics, disease spread, and information transfer. Social network analysis potentially offers insights into these processes but is rarely, if ever, used to investigate more than one species in a community. We therefore compared the social, temporal and spatial networks of sympatric Myotis bats (M. nattereri (Natterer's bats) and M. daubentonii (Daubenton's bats)), and asked: (1) are there long-lasting social associations within species? (2) do the ranges occupied by roosting social groups overlap within or between species? (3) are M. daubentonii bachelor colonies excluded from roosting in areas used by maternity groups? Results: Using data on 490 ringed M. nattereri and 978 M. daubentonii from 379 colonies, we found that both species formed stable social groups encompassing multiple colonies. M. nattereri formed 11 mixed-sex social groups with few (4.3%) inter-group associations. Approximately half of all M. nattereri were associated with the same individuals when recaptured, with many associations being long-term (>100 days). In contrast, M. daubentonii were sexually segregated; only a quarter of pairs were associated at recapture after a few days, and inter-sex associations were not long-lasting. Social groups of M. nattereri and female M. daubentonii had small roost home ranges (mean 0.2 km2 in each case). Intra-specific overlap was low, but inter-specific overlap was high, suggesting territoriality within but not between species. M. daubentonii bachelor colonies did not appear to be excluded from roosting areas used by females. Conclusions: Our data suggest marked species- and sex-specific patterns of disease and information transmission are likely between bats of the same genus despite sharing a common habitat. The clear partitioning of the woodland amongst social groups, and their apparent reliance on small patches of habitat for roosting, means that localised woodland management may be more important to bat conservation than previously recognised

    Observation of time-reversal violation in the B0 meson system

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    The individually named authors work collectively as The BABAR Collaboration. Copyright @ 2012 American Physical Society.Although CP violation in the B meson system has been well established by the B factories, there has been no direct observation of time-reversal violation. The decays of entangled neutral B mesons into definite flavor states (B0 or BÂŻÂŻÂŻ0), and J/ψK0L or ccÂŻK0S final states (referred to as B+ or B−), allow comparisons between the probabilities of four pairs of T-conjugated transitions, for example, BÂŻÂŻÂŻ0→B− and B−→BÂŻÂŻÂŻ0, as a function of the time difference between the two B decays. Using 468×106 BBÂŻÂŻÂŻ pairs produced in ΄(4S) decays collected by the BABAR detector at SLAC, we measure T-violating parameters in the time evolution of neutral B mesons, yielding ΔS+T=−1.37±0.14(stat)±0.06(syst) and ΔS−T=1.17±0.18(stat)±0.11(syst). These nonzero results represent the first direct observation of T violation through the exchange of initial and final states in transitions that can only be connected by a T-symmetry transformation.DOE and NSF (USA), NSERC (Canada), CEA and CNRS-IN2P3 (France), BMBF and DFG(Germany), INFN (Italy), FOM (The Netherlands), NFR (Norway), MES (Russia), MINECO (Spain), STFC (United Kingdom). Individuals have received support from the Marie Curie EIF (European Union), the A. P. Sloan Foundation (USA) and the Binational Science Foundation (USA-Israel)

    Measurement of ISR-FSR interference in the processes e+ e- --> mu+ mu- gamma and e+ e- --> pi+ pi- gamma

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    Charge asymmetry in processes e+ e- --> mu+ mu- gamma and e+ e- --> pi+ pi- gamma is measured using 232 fb-1 of data collected with the BABAR detector at center-of-mass energies near 10.58 GeV. An observable is introduced and shown to be very robust against detector asymmetries while keeping a large sensitivity to the physical charge asymmetry that results from the interference between initial and final state radiation. The asymmetry is determined as afunction of the invariant mass of the final-state tracks from production threshold to a few GeV/c2. It is compared to the expectation from QED for e+ e- --> mu+ mu- gamma and from theoretical models for e+ e- --> pi+ pi- gamma. A clear interference pattern is observed in e+ e- --> pi+ pi- gamma, particularly in the vicinity of the f_2(1270) resonance. The inferred rate of lowest order FSR production is consistent with the QED expectation for e+ e- --> mu+ mu- gamma, and is negligibly small for e+ e- --> pi+ pi- gamma.Comment: 32 pages,29 figures, to be submitted to Phys. Rev.
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