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51.
Angel Hannah Z. Priest Jeremy S. Stovall Jeremy P. Oswald Brian P. Weng Yuhui Williams Hans M. 《New Forests》2019,50(5):733-753
New Forests - While reclaimed loblolly pine (Pinus taeda L.) plantations in east Texas, USA have demonstrated similar aboveground productivity levels relative to unmined forests, there is interest... 相似文献
52.
Changes in performance,blood parameters,humoral and cellular immune responses in weanling piglets exposed to low doses of aflatoxin 总被引:4,自引:0,他引:4
Marin DE Taranu I Bunaciu RP Pascale F Tudor DS Avram N Sarca M Cureu I Criste RD Suta V Oswald IP 《Journal of animal science》2002,80(5):1250-1257
A feeding trial was conducted to evaluate the effect of aflatoxin (AF)-contaminated diets on growth and hematological and immunological parameters. Low doses of aflatoxins (140 and 280 ppb) were included in a corn-soybean diet provided for ad libitum consumption to 36 weanling piglets for a period of 4 wk. A "dose-related" decrease in weight gain was observed in treated animals. This effect was significant (P < 0.05) in the 280 ppb-treated group compared to the control group. Ingestion of AF-contaminated feed at either level had no effect on total red blood cell numbers or on their relative number of lymphocytes, monocytes, neutrophils, basophils, and eosinophils in blood. Likewise, AF did not alter globulin, albumins, or total protein concentrations in serum, nor did AF alter the expression of regulatory cytokines produced by either Th1 (IL-2) or Th2 (IL-4) lymphocyte subsets in phytohemagglutinin-stimulated blood samples. By contrast, AF had a biphasic effect on total white blood cell number; the low dose of AF (140 ppb) decreased the total number of white blood cells, whereas the high dose (280 ppb) had the opposite effect. Consumption of AF also increased the concentration of gamma-globulin in the serum. A reduced immune response induced by Mycoplasma agalactiae in the 280-ppb-treated group was also observed. Cytokine mRNA expression in phytohemagglutinin-stimulated blood cells indicated that AF decreased proinflammatory (IL-1beta, TNF-alpha) and increased anti-inflammatory (IL-10) cytokine mRNA expression. These results demonstrate that low doses of AF depress growth and alter many aspects of humoral and cellular immunity in pigs. 相似文献
53.
54.
Acetylcholine receptor synthesis in retina and transport to optic tectum in goldfish 总被引:4,自引:0,他引:4
Previous studies have suggested that the retinotectal system of the goldfish contains a nicotinic acetylcholine receptor (nAChR) that is sensitive to alpha-bungarotoxin. Extracellularly recorded field potentials elicited in response to visual stimulation can be blocked by alpha-bungarotoxin, and alpha-bungarotoxin can interfere with the maintenance of retinotectal synaptic connections. Whether the transmission between the retinal ganglion cells and the tectal cells is mediated by acetylcholine and whether nAChR's exist on the dendrites of tectal cells are questions that remain. The experiments described in this report were designed to determine the site of synthesis of the nAChR's associated with the goldfish retinotectal projection. Radioactive (35S-labeled) methionine was injected into either the eye or the tectal ventricle, and the incorporation of radioactivity into the nAChR was measured by immunoprecipitation. The use of this technique provides evidence that an nAChR associated with the goldfish retinotectal projection is synthesized in the retina and transported to the optic tectum, which suggests a presynaptic site of acetylcholine action on retinal terminals. 相似文献
55.
56.
An extremely fragmented timber supply, high harvesting costs, low profitability, high subsidies and insufficient competitiveness
characterise forest enterprises in Switzerland. In a case study using a forest district in the state of Solothurn as an example,
it was sought to identify strengths and weaknesses of wood production and to formulate possible improvement opportunities.
The results indicate that there is considerable potential for industry rationalisation. The greatest handicaps are the small
sized forest holdings, excessive numbers of staff, insufficient use of modern harvesting technology and costly business administration.
The most eminent of the proposed improvement measures are those which aim to increase concentration of timber supplies and
reduce production costs. These include greater centralising of timber sales as well as planning and steering of production,
making full use of modern harvesting systems, reducing transaction costs, supporting administration, planning and steering
of wood production with modern information technology and reducing input on stand tending. In principle, amelioration can
be best achieved by close cooperation with neighbours or even merger of enterprises. Consequently, there is a need for related
business tasks to be combined in functions. The paramount prerequisite for success is the willingness and readiness of all
affected stakeholders to make changes. The situation described is typical for Swiss forestry and the proposed solutions could
well be used as models for a wide range of Swiss forest districts. 相似文献
57.
Pinches MD Helps CR Gruffydd-Jones TJ Egan K Jarrett O Tasker S 《Journal of Feline Medicine and Surgery》2007,9(1):8-13
In this paper the design and use of a semi-quantitative real-time polymerase chain reaction assay (RT-PCR) for feline leukaemia virus (FeLV) provirus is described. Its performance is evaluated against established methods of FeLV diagnosis, including virus isolation and enzyme-linked immunoassay (ELISA) in a population of naturally infected cats. The RT-PCR assay is found to have both a high sensitivity (0.92) and specificity (0.99) when examined by expectation maximisation methods and is also able to detect a large number of cats with low FeLV proviral loads that were negative by other conventional test methods. 相似文献
58.
59.
Short-term kinetic response of enhanced methane oxidation in landfill cover soils to environmental factors 总被引:5,自引:0,他引:5
A. De Visscher Michael Schippers Oswald Van Cleemput 《Biology and Fertility of Soils》2001,33(3):231-237
This paper aims at a better understanding of methane oxidation under conditions that are representative of landfill cover
soils. The kinetics of methane oxidation were studied in landfill cover soils that had been exposed to high methane mixing
ratios. This was done in batch experiments, under various environmental conditions. V
max increased exponentially with temperature in the range 5–35 °C, with a Q
10 value of 2.8. K
m increased approximately linearly in this range from 1.2 μM to 7 μM. Consequently, the influence of temperature on methane
consumption was more pronounced at high concentrations than at low concentrations. The inhibition by ammonium of methane consumption
was much stronger after 6–7 months of exposure to high methane mixing ratios than after 5–7 weeks of exposure, indicating
that there was a shift of dominating methanotrophic species in soils after long exposure times. Additions of nitrifying sludge
or compost to soils initially inhibited methane oxidation, followed by a stimulation after a few days.
Received: 19 May 2000 相似文献
60.
Adand A Medjigbodo Eric G Sonounameto Oswald Y Djihinto Emmanuella Abbey Esther B Salavi Laurette Djossou Athanase Badolo Luc S Djogbnou 《Journal of insect science (Online)》2021,21(4)
The insecticide resistance in Anopheles gambiae mosquitoes has remained the major threat for vector control programs but the fitness effects conferred by these mechanisms are poorly understood. To fill this knowledge gap, the present study aimed at testing the hypothesis that antibiotic oxytetracycline could have an interaction with insecticide resistance genotypes and consequently inhibit the fecundity in An. gambiae. Four strains of An. gambiae: Kisumu (susceptible), KisKdr (kdr (L1014F) resistant), AcerKis (ace-1 (G119S) resistant) and AcerKdrKis (both kdr (L1014F) and ace-1 (G119S) resistant) were used in this study. The different strains were allowed to bloodfeed on a rabbit previously treated with antibiotic oxytetracycline at a concentration of 39·10–5 M. Three days later, ovarian follicles were dissected from individual mosquito ovaries into physiological saline solution (0.9% NaCl) under a stereomicroscope and the eggs were counted. Fecundity was substantially lower in oxytetracycline-exposed KisKdr females when compared to that of the untreated individuals and oxytetracycline-exposed Kisumu females. The exposed AcerKis females displayed an increased fecundity compared to their nontreated counterparts whereas they had reduced fecundity compared to that of oxytetracycline-exposed Kisumu females. There was no substantial difference between the fecundity in the treated and untreated AcerKdrKis females. The oxytetracycline-exposed AcerKdrKis mosquitoes had an increased fecundity compared to that of the exposed Kisumu females. Our data indicate an indirect effect of oxytetracycline in reducing fecundity of An. gambiae mosquitoes carrying kdrR (L1014F) genotype. These findings could be useful for designing new integrated approaches for malaria vector control in endemic countries. 相似文献