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The fate of 15N-labelled nitrate additions to a northern hardwood forest in eastern Maine,USA 总被引:5,自引:0,他引:5
Knute J. Nadelhoffer Martha R. Downs Brian Fry John D. Aber Alison H. Magill Jerry M. Melillo 《Oecologia》1995,103(3):292-301
We followed the movements of 15N-labelled nitrate additions into biomass and soil pools of experimental plots (15×15 m each) in a mid-successional beech-maple-birch-spruce forest in order to identify sinks for nitrate inputs to a forest ecosystem. Replicate plots (n=3) were spray-irrigated with either 28 or 56 kg N ha–1 year–1 using 15N-labelled nitric acid solutions (15N = 344 ) during four successive growing seasons (April–October). The 15N contents of foliage, bolewood, forests floor and mineral soil (0–5 cm) increased during the course of treatments. Mass balance calculations showed that one-fourth to one-third of the nitrate applied to forest plots was assimilated into and retained by above ground plant tissues and surface soil horizons at both rates of nitrate application. Plant and microbial assimilation were of approximately equal importance in retaining nitrate additions to this forest. Nitrate use among tree species varied, however, with red spruce showing lower rates of nitrate assimilation into foliage and bolewood than American beech and other deciduous species. 相似文献
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K Chamari W Briki A Farooq T Patrick T Belfekih CP Herrera 《Biology of sport / Institute of Sport》2016,33(1):49-56
This study assessed selected measures of cognitive function in trained cyclists who observed daylight fasting during Ramadan. Eleven cyclists volunteered to participate (age: 21.6±4.8 years, VO2max: 57.7±5.6 ml kg−1·min−1) and were followed for 2 months. Cognitive function (Cambridge Neuropsychological Test Automated Battery (CANTAB), Reaction Time index (RTI) and Rapid Visual Information Processing (RVP) tests) and sleep architecture (ambulatory EEG) were assessed: before Ramadan (BR), in the 1st week (RA1) and 4th week of Ramadan (RA4), and 2 weeks post-Ramadan (PR). Both cognitive tests were performed twice per day: before and after Ramadan at 8-10 a.m. and 4-6 p.m., and during Ramadan at 4-6 p.m. and 0-2 a.m., respectively. Training load (TL) by the rating of perceived exertion (RPE) method and wellness (Hooper index) were measured daily. If the TL increased over the study period, this variable was stable during Ramadan. The perceived fatigue and delayed onset muscle soreness (DOMS) increased at RA4. Sleep patterns and architecture showed clear disturbances, with significant increases in the number of awakenings and light sleep durations during Ramadan (RA1 and RA4), together with decreased durations of deep and REM sleep stages at PR. RTI (simple and multiple reaction index) reaction and movement times did not vary over the study period. The RVP test showed reduced false alarms during Ramadan, suggesting reduced impulsivity. Overall accuracy significantly increased at RA1, RA4 and PR compared to baseline. At RA4, the accuracy was higher at 0-2 a.m. compared to 4-6 p.m. Despite the observed disturbances in sleep architecture, Ramadan fasting did not negatively impact the cognitive performance of trained cyclists from the Middle East. 相似文献
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Niels H Chavannes Juanita HJ Vernooy Tjard RJ Schermer Jan A Jacobs Mieke A Dentener Chris van Weel Onno CP van Schayck Emiel FM Wouters 《BMC pulmonary medicine》2006,6(1):1-7
Background
Although both smoking and respiratory complaints are very common, tools to improve diagnostic accuracy are scarce in primary care. This study aimed to reveal what inflammatory patterns prevail in clinically established diagnosis groups, and what factors are associated with eosinophilia.Method
Induced sputum and blood plasma of 59 primary care patients with COPD (n = 17), asthma (n = 11), chronic bronchitis (CB, n = 14) and smokers with no respiratory complaints ('healthy smokers', n = 17) were collected, as well as lung function, smoking history and clinical work-up. Patterns of inflammatory markers per clinical diagnosis and factors associated with eosinophilia were analyzed by multiple regression analyses, the differences expressed in odds ratios (OR) with 95% confidence intervals.Results
Multivariately, COPD was significantly associated with raised plasma-LBP (OR 1.2 [1.04–1.37]) and sTNF-R55 in sputum (OR 1.01 [1.001–1.01]), while HS expressed significantly lowered plasma-LBP (OR 0.8 [0.72–0.95]). Asthma was characterized by higher sputum eosinophilic counts (OR 1.3 [1.05–1.54]), while CB showed a significantly higher proportion of sputum lymphocytic counts (OR 1.5 [1.12–1.9]). Sputum eosinophilia was significantly associated with reversibility after adjusting for smoking, lung function, age, gender and allergy.Conclusion
Patterns of inflammatory markers in a panel of blood plasma and sputum cells and mediators were discernable in clinical diagnosis groups of respiratory disease. COPD and so-called healthy smokers showed consistent opposite associations with plasma LBP, while chronic bronchitics showed relatively predominant lymphocytic inflammation compared to other diagnosis groups. Only sputum eosinophilia remained significantly associated with reversibility across the spectrum of respiratory disease in smokers with airway complaints. 相似文献27.
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Ramasamy Perumal Thomas Isakeit Monica Menz Seriba Katile Eun-Gyu No Clint W. Magill 《Mycological Research》2006,110(4):471-478
Sorghum downy mildew, caused by the obligate oomycete Peronosclerospora sorghi, has been controlled through the use of resistant cultivars and seed treatment with metalaxyl. A recent outbreak in fields planted with treated seed revealed the presence of a metalaxyl-resistant variant. Here, PCR-based methods including amplification from RAPD primers and two systems of automated AFLP analysis have been used to detect DNA-level genetic variation among 14 isolates including metalaxyl-resistant and susceptible isolates, as well as representatives of common pathotypes 1 and 3 and a new pathotype. In total, 1708 bands were detected after amplification of EcoRI/MseI fragments with 16 primer combinations. Nearly as many amplified products were observed using eight primer pairs with three-base extensions (LI-COR) as with two-base extensions (ABI-Prism genetic capillary system). Approximately 25 % of the bands were polymorphic across the 14 isolates, with the majority of differences specific to the pathotype P1 isolate. The AFLP banding patterns are consistent with metalaxyl resistance and the new pathotype having evolved from pathotype 3. 相似文献
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Elizabeth R. Sharlow David Close Tongying Shun Stephanie Leimgruber Robyn Reed Gabriela Mustata Peter Wipf Jacob Johnson Michael O'Neil Max Gr?gl Alan J. Magill John S. Lazo 《PLoS neglected tropical diseases》2009,3(11)
Patients with clinical manifestations of leishmaniasis, including cutaneous leishmaniasis, have limited treatment options, and existing therapies frequently have significant untoward liabilities. Rapid expansion in the diversity of available cutaneous leishmanicidal chemotypes is the initial step in finding alternative efficacious treatments. To this end, we combined a low-stringency Leishmania major promastigote growth inhibition assay with a structural computational filtering algorithm. After a rigorous assay validation process, we interrogated ∼200,000 unique compounds for L. major promastigote growth inhibition. Using iterative computational filtering of the compounds exhibiting >50% inhibition, we identified 553 structural clusters and 640 compound singletons. Secondary confirmation assays yielded 93 compounds with EC50s ≤ 1 µM, with none of the identified chemotypes being structurally similar to known leishmanicidals and most having favorable in silico predicted bioavailability characteristics. The leishmanicidal activity of a representative subset of 15 chemotypes was confirmed in two independent assay formats, and L. major parasite specificity was demonstrated by assaying against a panel of human cell lines. Thirteen chemotypes inhibited the growth of a L. major axenic amastigote-like population. Murine in vivo efficacy studies using one of the new chemotypes document inhibition of footpad lesion development. These results authenticate that low stringency, large-scale compound screening combined with computational structure filtering can rapidly expand the chemotypes targeting in vitro and in vivo Leishmania growth and viability. 相似文献
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J Davenport P.G Moore S.H Magill L.A Fraser 《Journal of experimental marine biology and ecology》1998,230(2):476-234
Dogwhelks, Nucella lapillus eat both barnacles and mussels, Mytilus edulis. However, mussels are dangerous prey because they can snare and immobilize dogwhelks with their byssi. Despite this danger, adult dogwhelks are common inside mussel hummocks or stacks found on mature mussel beds. The whelks live in debris-filled chambers within the hummocks, unsnared by byssi. Evidence is presented to show that this is a highly favourable microhabitat for dogwhelks. Condition index (CI) measurements showed that mean CI for “hummock” dogwhelks was 20.99 in early spring, 29.65 in midsummer and 34.86 in early winter. In comparison, CI values for dogwhelks from nearby barnacle zones were 20.13, 25.03 and 24.66 respectively. The summer and winter CI values of “hummock” dogwhelks were enhanced to a highly significant extent. Data are also presented to show that shore elevation or dogwhelk shell height (over the size range of animals studied) had no confounding effect on this result. Predicted flesh and shell mass values for a standard 25 mm high whelk showed that occupation of hummocks was associated with a thin-walled shell morphology, and that the shell mass became proportionately lower in summer and early winter. A feeding experiment showed that CI rises slowly, even in dogwhelks fed to satiation on mussels. Dogwhelks were taken from the barnacle zone in March 1997 and either fed to satiation on Mytilus or starved, whilst being held in seawater at ambient seawater temperature. The CI of fed dogwhelks rose from 19.7 to 27.4 in 3 months, while that of starved Nucella fell from 19.7 to 16.3. In the meantime, the CI of dogwhelks in situ in the barnacle zone had risen from 19.7 to 23.8. Hence, 3 months' satiation ration had led to a nett 3.6 unit rise in CI; starvation to a nett 7.5 unit fall. All of the changes in CI were due to changes in flesh mass; shell mass was stable. Since “hummock” dogwhelks collected in early winter have a CI value about 10.2 units greater than barnacle zone dogwhelks, this indicates that “hummock” dogwhelks are long-term inhabitants of this microhabitat. 相似文献