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351.
Jean Weber Marc Ducousso Foong Yee Tham Sophie Nourissier-Mountou Antoine Galiana Yves Prin Sing Kong Lee 《Biology and Fertility of Soils》2005,41(4):233-239
Acacia mangium grown in aeroponic culture was co-inoculated with selected strains of Bradyrhizobium sp. and Glomus intraradices. A single-step technique using alginate as an embedding and sticking agent for an inoculum composed of arbuscular mycorrhiza (AM)-infected sheared roots was used to infect plants. This method resulted in the successful establishment of AM in 100% of the inoculated plants after 7 weeks. The results indicated that dual microbial inoculation with Glomus intraradices strain S-043 and Bradyrhizobium strain AUST 13C stimulated the growth of A. mangium in aeroponic culture. The effects of single and dual microbial inoculations were also evaluated at two levels of P in the nutrient medium. A concentration of 5 mg P kg–1 stimulated the development of AM without affecting plant development or establishment of Bradyrhizobium symbiosis. In contrast, saplings supplemented with a higher concentration of P (25 mg kg–1) alone or co-inoculated with Bradyrhizobium had lower AM frequencies. 相似文献
352.
Dufour C Da Silva E Potier P Queneau Y Dangles O 《Journal of agricultural and food chemistry》2002,50(12):3425-3430
Three tests of increasing complexity were used to assess the antioxidant activity of five synthetic gallic esters of sucrose bearing 3, 6, 7, or 8 galloyl units. In addition, two of these compounds had 1 or 2 hydrocarbon (C10-C12) acyl chains. Reaction with the DPPH radical led to the evaluation of the number of radicals trapped per galloyl unit n (3-4), as well as the apparent second-order rate constant for H atom donation k (1200-1500/M/s). These results indicated similar contribution and reactivity of all the galloyl units. Inhibition of the AAPH-initiated peroxidation of linoleic acid in a micellar medium confirmed the additive contribution of the galloyl units, whereas the presence of the hydrocarbon acyl chains had no influence. These results suggest an inhibition of initiation at high antioxidant levels and an underlying prooxidant effect of the galloyl radicals at low concentrations. Finally, LDL peroxidation was inhibited in proportion to the number of galloyl units, in agreement with the preceding tests. 相似文献
353.
Effects of two tillage treatments and two fallow period managements under continuous maize cropping on soil temperature, soil water dynamics and maize development were evaluated over a 4-year period (2005–2008). Tillage treatments were conventional tillage with mouldboard ploughing and conservation tillage with disk harrowing. The fallow period managements were bare soil or soil sown with a cover crop after maize harvest. For each year, topsoil temperature (0–20 cm-depth) was lower under conservation tillage systems at sowing, from 0.8 to 2.8 °C. This difference persisted several weeks after sowing, and disappeared afterwards. Under conservation tillage, higher soil water content was generally measured at sowing and during the growing season strong fluctuations were observed at 40 cm-depth. Under conventional tillage, soil water content varied mainly in the tilled layer (20 cm-depth). Tillage and fallow period management affected water flow rate at 40 cm-depth. During the maize growing season, the lowest drainage volumes were measured in 2006 and 2008 under conservation tillage in cover cropped plots. No effect of fallow period management on maize development and yield was observed but significantly higher yields were measured under conservation tillage in 2005 and 2007. From this 4-year experiment under continuous maize cropping, using cover crop and reducing tillage intensity enhanced water use efficiency while maintaining or increasing maize yields. 相似文献
354.
Guy MM Tremblay M Voyer N Gauthier SF Pouliot Y 《Journal of agricultural and food chemistry》2011,59(2):720-726
The objective of the present work was to investigate the physicochemical conditions that trigger the self-assembly of peptide β-lg f1-8 and therefore lead to nanofibers and hydrogel formation. Nanostructures formed by self-assembly of peptide β-lg f1-8 in the pH range of 2.0-11.0 were studied by transmission electron microscopy (TEM). Hydrogel formation was studied as a function of pH and resulted in evidence of a link between hydrogel formation and the charge distribution carried by the peptide structure. Finally, circular dichroism (CD) spectroscopy was used to characterize the effects of peptide concentration (0.4-2.0 mg/mL), ionic strength (0-1 M NaCl), and temperature (20-80 °C) on the secondary structure of peptide β-lg f1-8. Hydrogels were obtained at peptide concentrations above 2.5 mg/mL. Peptide concentration and pH adjustment were shown to trigger self-assembly of β-lg f1-8, but increasing ionic strength had no effect. Heating to 80 °C induced a stronger CD signal intensity due to an increase in solubility of the peptide, whereas only slight changes in CD pattern were found upon cooling to 20 °C. Overall, results emphasize the role of particular molecular interactions in β-sheet self-assembly of peptide β-lg f1-8 and pH-dependent electrostatic interactions occurring between β-lg f1-8 units, which can explain its propensity to self-assembly. 相似文献
355.
ObjectiveTo evaluate interchangeability of a thermodilution based STAT mode continuous cardiac output (CCO) measurement method with bolus thermodilution (BTD).Study designRandomized crossover study.AnimalsTen 9 month old healthy male sheep.MethodsEach sheep was anaesthetized twice for laparoscopy. On one occasion mechanical ventilation was used immediately after anaesthetic induction (IPPV treatment) and on the other occasion the start of IPPV was delayed and two periods of alveolar recruitment manoeuvres were also performed (RM treatment). Cardiac output (CO) was measured simultaneously with both CCO and BTD at 6 time points. Data were analysed using difference versus mean plots. A priori limits of acceptance were set at ±30% of the mean of every paired measurement. If <5% of the data fell outside of these limits (Chi-square test, p < 0.05) the interchangeability of methods was accepted. Proportions of data outside of these limits were also compared between treatments (Fisher's test, p < 0.05). Cardiac output data from each treatment and measurement method were also analyzed separately with one-factorial anova and Bonferroni test (p < 0.05).ResultsA total of 119 measurements were obtained. Cardiac output ranged from 1.9 to 10.4 L minute?1 (CCO) and from 1.1 to 9.8 L minute?1 (BTD). The bias and limits of agreement were 0.5 ± 1.9 L minute?1. More than 5% of all data fell outside of the limits of acceptance (24/119), and a larger proportion fell outside of these limits in the RM (20/59) compared to the IPPV treatment (4/60). The Bonferroni test detected significant decreases of CO over time in both treatments when measured with BTD but not with CCO.Conclusions and clinical relevanceThe STAT mode CCO method is not interchangeable with BTD during acute haemodynamic changes caused by recruitment manoeuvres, thus the results of STAT mode CCO should be interpreted with caution because decreases in CO may not be detected. 相似文献
356.
Future climate will alter the soil cover of mosses and snow depths in the boreal forests of eastern Canada. In field manipulation experiments, we assessed the effects of varying moss and snow depths on the physiology of black spruce (Picea -mariana (Mill.) B.S.P.) and trembling aspen (Populus tremuloides Michx.) in the boreal black spruce forest of western Québec. For 1 year, naturally regenerated 10-year-old spruce and aspen were grown with one of the following treatments: additional N fertilization, addition of sphagnum moss cover, removal of mosses, delayed soil thawing through snow and hay addition, or accelerated soil thawing through springtime snow removal. Treatments that involved the addition of insulating moss or snow in the spring caused lower soil temperature, while removing moss and snow in the spring caused elevated soil temperature and thus had a warming effect. Soil warming treatments were associated with greater temperature variability. Additional soil cover, whether moss or snow, increased the rate of photosynthetic recovery in the spring. Moss and snow removal, on the other hand, had the opposite effect and lowered photosynthetic activity, especially in spruce. Maximal electron transport rate (ETR(max)) was, for spruce, 39.5% lower after moss removal than with moss addition, and 16.3% lower with accelerated thawing than with delayed thawing. Impaired photosynthetic recovery in the absence of insulating moss or snow covers was associated with lower foliar N concentrations. Both species were affected in that way, but trembling aspen generally reacted less strongly to all treatments. Our results indicate that a clear negative response of black spruce to changes in root-zone temperature should be anticipated in a future climate. Reduced moss cover and snow depth could adversely affect the photosynthetic capacities of black spruce, while having only minor effects on trembling aspen. 相似文献
357.
Jacques Bernier Michel Fournier Yves Blais Pierre Lombardi Gaston Chevalier Krzysztof Krzystyniak 《Pesticide biochemistry and physiology》1988,30(3)
Immunotoxicity of a carbamate pesticide, aminocarb (Matacil), introduced orally in sublethal doses to C57B1/6 inbred mice, has been compared to the immunosupressive effects of the organochlorine pesticide, dieldrin (served as a positive control), in bacterial and viral infections. In vivo infection of pesticide-exposed mice with Salmonella typhimurium and mouse hepatitis virus 3 (MHV3) showed that two subsequent
LD50 doses of aminocarb did not decrease the resistance of animals to the pathogens, whereas exposure to dieldrin resulted in augmented mortality. In vitro studies showed that the spread of MHV3 virus infection and virus-induced cytopathic effects (cpe) were augmented in peritoneal macrophages after exposure to aminocarb, albeit to a much less extent than in the dieldrin group. Similarly, a decrease in the anti-MHV3 IgM serum antibody titer by aminocarb was less marked than in the dieldrin group. Alternatively, immunization of animals with a neutral antigen, sheep red blood cells (SRBC), showed a significant increase in the anti-SRBC humoral response 10 days after a single oral exposure to
LD50 aminocarb. The cellular immune response, determined by mixed lymphocyte reaction, was unaffected by sublethal aminocarb exposure. In addition, macrophage antigen processing of a single protein, avidin, was unaffected by aminocarb, contrary to the inhibition of avidin processing in macrophages from dieldrin-gavaged mice. The data do not indicate that immunotoxic properties are associated with aminocarb, and only slight effects with high sublethal doses of orally given aminocarb on macrophage susceptibility to the MHV3 viral pathogen were observed at a terminal phase of the disease. 相似文献
358.
Objective— To describe anesthetic management of endoscopic electrosurgical removal of a bronchial carcinoma, partially blocking the right main stem bronchus in a Cocker Spaniel.
Study Design— Clinical case report.
Animals— Dog with a bronchial carcinoma.
Methods— To allow sufficient space for the endoscope and to avoid an oxygen-rich gas mixture in the trachea, which carries the risk of an airway fire when electrocautery is used, a 1 lumen endobronchial tube (EBT) was inserted into the left main stem bronchus. One-lung ventilation (OLV) started with a volume-controlled ventilator was switched to pressure-controlled ventilation in combination with positive end-expiratory pressure (PEEP).
Results— Resection of the bronchial carcinoma was successful. The dog was hypercapnic throughout the procedure and a high alveolar-arterial oxygen gradient was measured.
Conclusion— An EBT may be a feasible and safe option to provide OLV for bronchoscopic electrocautery with a closed thoracic cavity in dogs.
Clinical Relevance— EBT intubation for OLV should be considered as part of the anesthetic management of airway diseases treated with bronchoscopic electrocautery. 相似文献
Study Design— Clinical case report.
Animals— Dog with a bronchial carcinoma.
Methods— To allow sufficient space for the endoscope and to avoid an oxygen-rich gas mixture in the trachea, which carries the risk of an airway fire when electrocautery is used, a 1 lumen endobronchial tube (EBT) was inserted into the left main stem bronchus. One-lung ventilation (OLV) started with a volume-controlled ventilator was switched to pressure-controlled ventilation in combination with positive end-expiratory pressure (PEEP).
Results— Resection of the bronchial carcinoma was successful. The dog was hypercapnic throughout the procedure and a high alveolar-arterial oxygen gradient was measured.
Conclusion— An EBT may be a feasible and safe option to provide OLV for bronchoscopic electrocautery with a closed thoracic cavity in dogs.
Clinical Relevance— EBT intubation for OLV should be considered as part of the anesthetic management of airway diseases treated with bronchoscopic electrocautery. 相似文献
359.
Context
Knowledge of how environmental gradients generate changes in community composition across forest landscapes (β-diversity) represents a critical issue in the era of global change, which exerts especially powerful impacts by shifting disturbance regimes.Objectives
We analyzed the response of tree communities to increased disturbance rates that were linked to European settlement at the temperate-boreal interface of eastern Canada. We tested whether disturbance has led to spatial homogenization or heterogenization, and to decoupling or strengthening of community-environment relationships.Methods
We used a reconstruction of pre-industrial tree communities based on historical land survey records (1854–1935), together with modern data, to assess changes in tree β-diversity patterns. Then, β-diversity was partitioned into fractions explained by spatial (dbMEM) and environmental variables (latitude, elevation, slope, drainage and surface deposits) in order to assess changes in spatial structures and community-environment relationships.Results
In pre-industrial times, environmental variables explained only a small proportion of β-diversity since dominant taxa were present across the range of environmental gradients, whereas habitat specialists were very rare. Between pre-industrial and modern times, our analysis highlights an increase in β-diversity and the proportion of β-diversity that was explained by environmental variables. Increased disturbance rates have favored early-successional habitat specialist taxa and reduced the habitat breadth of pre-industrial generalists, thereby increasing the strength of community-environment relationships.Conclusions
Our results support that disturbance can alter the strength of community-environment relationships and also suggest that functional traits of species within the regional pool could predict whether or not disturbance alters such relationships.360.
OBSERVATIONS: Two healthy obese, seven-year-old, female Rottweilers weighing 40 and 57 kg were submitted for cranial cruciate repair. They were premedicated with intravenous methadone (0.1 mg kg(-1)) and acepromazine (0.01 and 0.02 mg kg(-1)). Anesthesia was induced with propofol (3.6 and 2.5 mg kg(-1)) and maintained with isoflurane in oxygen using a circle breathing system. The dogs were placed in sternal recumbency and epidural injection of lidocaine/bupivacaine or lidocaine/bupivacaine/morphine (0.2 mL/kg, 8 and 11 mL) was carried out over 1.5 and 4 minutes. Epidural pressures were 79 and 72 mmHg at the end of the injections. The first dog's heart rate decreased from 80 to 65 beats minute(-1) with a second degree atrioventricular (AV) block. The arterial pressure decreased from 100 to 50 mmHg. These responded to atropine (0.01 mg kg(-1) IV). The second dog's heart rate decreased from 120 to 60 beats minute(-1) while arterial pressure decreased from 72 to 38 mmHg. No treatment was given and heart rate and arterial blood pressure returned to acceptable ranges. CONCLUSIONS: These cases suggest that large increases in epidural pressure may cause significant cardiovascular effects. This may be avoided by using lower volumes and discontinuing injection if significant back pressure is detected. 相似文献