Influence of litter chemistry and stoichiometry on glucan depolymerization during decomposition of beech (Fagus sylvatica L.) litter     

Leitner S  Wanek W  Wild B  Haemmerle I  Kohl L  Keiblinger KM  Zechmeister-Boltenstern S  Richter A 《Soil biology & biochemistry》2012,50(6):174-187

Glucans like cellulose and starch are a major source of carbon for decomposer food webs, especially during early- and intermediate-stages of decomposition. Litter quality has previously been suggested to notably influence decomposition processes as it determines the decomposability of organic material and the nutrient availability to the decomposer community. To study the impact of chemical and elemental composition of resources on glucan decomposition, a laboratory experiment was carried out using beech (Fagus sylvatica, L.) litter from four different locations in Austria, differing in composition (concentration of starch, cellulose and acid unhydrolyzable residue or AUR fraction) and elemental stoichiometry (C:N:P ratio). Leaf litter was incubated in mesocosms for six months in the laboratory under controlled conditions. To investigate the process of glucan decomposition and its controls, we developed an isotope pool dilution (IPD) assay using (13)C-glucose to label the pool of free glucose in the litter, and subsequently measured the dilution of label over time. This enabled us to calculate gross rates of glucose production through glucan depolymerization, and glucose consumption by the microbial community. In addition, potential activities of extracellular cellulases and ligninases (peroxidases and phenoloxidases) were measured to identify effects of resource chemistry and stoichiometry on microbial enzyme production. Gross rates of glucan depolymerization and glucose consumption were highly correlated, indicating that both processes are co-regulated and intrinsically linked by the microbial demand for C and energy and thereby to resource allocation to enzymes that depolymerize glucans. At early stages of decomposition, glucan depolymerization rates were correlated with starch content, indicating that starch was the primary source for glucose. With progressing litter decomposition, the correlation with starch diminished and glucan depolymerization rates were highly correlated to cellulase activities, suggesting that cellulose was the primary substrate for glucan depolymerization at this stage of decomposition. Litter stoichiometry did not affect glucan depolymerization or glucose consumption rates early in decomposition. At later stages, however, we found significant negative relationships between glucan depolymerization and litter C:N and AUR:N ratio and a positive relationship between glucan depolymerization and litter N concentration. Litter C:N and C:P ratios were negatively related to cellulase, peroxidase and phenoloxidase activities three and six months after incubation, further corroborating the importance of resource stoichiometry for glucan depolymerization after the initial pulse of starch degradation.  相似文献   

The effect of vitamin C supplementation in healthy dogs on antioxidative capacity and immune parameters     

M. Hesta  C. Ottermans  S. Krammer‐Lukas  J. Zentek  P. Hellweg  J. Buyse  G. P. J. Janssens 《Journal of animal physiology and animal nutrition》2009,93(1):26-34

The aim of the study was to investigate the ability of vitamin C to increase the antioxidative and immunomodulating potential in healthy dogs. Fifteen dogs were tested for the effects of orally administered vitamin E (60 mg dl‐α tocopheryl acetate) in combination with vitamin C (0, 30 or 60 mg ascorbic acid crystalline). Three treatments (0, 30, 60 mg vitamin C) were tested in a 3 × 3 cross‐over study in three periods of 36 days. Pre‐prandial blood samples were taken for analysis of vitamins C, E, A, retinyl palmitate and stearate, antioxidant status [Thiobarbituric acid reactive substances (TBARS) and uric acid], biochemical and haematological analysis. Subpopulations of lymphocytes, mitogen‐induced peripheral blood mononuclear cell proliferation (PBMC) and serum IgA and IgG concentrations were determined. There was a trend (p = 0.056) for an increased plasma vitamin C concentration by vitamin C supplementation. There was no evidence that dietary treatment altered neither the other plasma vitamin concentrations nor TBARS and uric acid concentrations nor the subpopulations of the lymphocytes except for the number of CD4⁺ lymphocytes that increased with vitamin C supplementation. There was no effect of vitamin C on serum IgA and IgG concentration. A significant time × treatment interaction was demonstrated on PBMC’s to pokeweed, with an increase observed by 30 mg vitamin C supplementation but a decrease by 60 mg vitamin C supplementation. There was no clear evidence for an effect of dietary vitamin C on antioxidative capacity in healthy dogs fed a diet with vitamin E concentrations well above the recommendations. Yet, a limited number of immunological parameters were slightly affected.  相似文献   

Synthesis of biaryls via catalytic decarboxylative coupling     

Goossen LJ  Deng G  Levy LM 《Science (New York, N.Y.)》2006,313(5787):662-664

We present a safe and convenient cross-coupling strategy for the large-scale synthesis of biaryls, commercially important structures often found in biologically active molecules. In contrast to traditional cross-couplings, which require the prior preparation of organometallic reagents, we use a copper catalyst to generate the carbon nucleophiles in situ, via decarboxylation of easily accessible arylcarboxylic acid salts. The scope and potential economic impact of the reaction are demonstrated by the synthesis of 26 biaryls, one of which is an intermediate in the large-scale production of the agricultural fungicide Boscalid.  相似文献   

Captive breeding and a threatened gecko     

Kratochvíl L 《Science (New York, N.Y.)》2006,313(5789):915; author reply 915

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Cell biology. The stress of finding NEMO     

Bartek J  Lukas J 《Science (New York, N.Y.)》2006,311(5764):1110-1111

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An in vitro study on the postinfection activities of copper hydroxide and copper sulfate against conidia of Venturia inaequalis     

Montag J  Schreiber L  Schönherr J 《Journal of agricultural and food chemistry》2006,54(3):893-899

The postinfection activities of copper hydroxide [Cu(OH)2] and copper sulfate (CuSO4) against apple scab (Venturia inaequalis) were evaluated in an in vitro study. Our intention was to support the aim of reducing copper application rates by appropriate timing of applications. Experiments were conducted at 20 degrees C with leaf disks and isolated cuticular membranes (CM) of Malus x domestica 'Gloster' and 'Elstar'. Conidia of V. inaequalis were used as the inoculum. In untreated controls, 7.9 and 33.2% of germinated conidia formed primary stromata 24 and 48 h after inoculation, respectively. Treatments with copper compounds were applied 24 and 48 h after inoculation, which was 16 and 40 h after infection had occurred. When working with CM and using fluorescein diacetate as a vital stain, vital and dead stromata could be distinguished. Treatment effects were assessed 72 h after inoculation by counting vital (fluorescing) primary stromata. With leaf disks, the number of stromata was counted using KOH-aniline blue fluorescence staining. Cu(OH)2 and CuSO4 showed postinfection activity and killed primary stromata, provided that the surface of the CM was kept wet. Cu(OH)2 was more effective than CuSO4 and was able to kill all primary stromata 24 h after inoculation at concentrations of 116 and 231 mg L(-1). When Cu(OH)2 was applied at 116 mg L(-1) to leaf disks 24 h after inoculation, the number of primary stromata did not significantly differ from the control. Results indicate different modes of action for the highly water soluble CuSO4 and the slightly soluble Cu(OH)2. This supports the hypothesis that spore exudates react with insoluble copper compounds and form highly toxic copper complexes. Application of Cu(OH)2 to dry CM did not kill primary stromata. Hence, for Cu(OH)2 to exert postinfection activity, leaves must be wet. In the field, this cannot be guaranteed and a postinfection application of Cu(OH)2 cannot be recommended.  相似文献   

Variability Of The Cadmium Content In HypericumSpecies Collected In Eastern Austria     

Remigius Chizzola  Brigitte Lukas 《Water, air, and soil pollution》2006,170(1-4):331-343

In Hypericumspecies some specimens have been found to display higher levels of the toxic heavy metal Cd than the proposed guide value of 0.5mgkg. Plant and soil samples from various regions in Eastern Austria were collected to study the variability in the Cd content of the herbs and relate it to selected soil properties and soil micronutrient contents. The soils contained between 0.01 and 0.44mgkg^?1Cd in the dry soil. Altogether about 7% of the collected plant samples exceeded 0.5mgkg^?1Cd of dry shoots, the proposed guide value for the drug Herba Hyperici. Plants low in Cd were found on sites in the Alpenvorland, the Hainburger Berge, the Eastern Viennese Basin and the Northern Limestone Alps where the levels did not exceed 0.3mgkg^?1Cd of dry shoots. Higher Cd levels in the plants were present in material from the Waldviertel, the Southern Wienerwald and the Semmering region where often bioaccumulation factors for Cd above 1 could be calculated. In these regions the soil pH and carbonate content was somewhat lower than in other regions whereas the soil organic carbon varied greatly. In the Waldviertel some plants from a field were somewhat higher in Cd than nearby plants from the natural vegetation. In a regression analysis, the soil pH, soil organic carbon and soil Cd content were the main factors influencing Cd accumulation in the plant shoots.  相似文献   

Inhibiting effects of resveratrol and its glucoside piceid against Venturia inaequalis, the causal agent of apple scab     

Schulze K  Schreiber L  Szankowski I 《Journal of agricultural and food chemistry》2005,53(2):356-362

Resveratrol is a phytoalexin produced in different unrelated plant species such as grapevine and peanut. The effect of resveratrol and its glucoside trans-resveratrol-3-O-beta-D-glycopyranosid (piceid) against Venturia inaequalis, the causal agent of apple scab, was evaluated using a newly established test based on enzymatically isolated cuticular membranes (CMs) from apple (Malus domestica Borkh.) leaves. The test substances resveratrol and piceid were either sorbed to CMs before inoculation with spores or were applied simultaneously with the Venturia inaequalis spores to the CMs, and their effect on germination, appressoria formation, and penetration was examined. Resveratrol had no influence on spore germination but a significant inhibiting effect on penetration when applied simultaneously as well as before. A percentage inhibition of 89.7 +/- 11.5 and 61.8 +/- 35.1 was observed for simultaneous and preapplication, respectively. The resveratrol glucoside piceid had a significant inhibitory effect on germination and completely inhibited penetration of the fungus at concentrations between 200 and 400 microg mL(-1) when applied simultaneously with the spores to the CMs. On piceid-enriched CM (preapplication), spores germinated but penetration was inhibited nearly completely (96.1 +/- 5.1%). Thus, in vitro experiments showed that resveratrol and its glucoside in fact could contribute to improving the pathogen resistance of apple leaves.  相似文献   

Einfluß langjährig ökologischer und konventioneller Bewirtschaftung auf Regenwurmpopulationen (Lumbricidae)     

Lukas Pfiffner 《植物养料与土壤学杂志》1993,156(3):259-265

Long-term effects of biological and conventional farming on earthworm populations In a long-term trial the earthworm populations of two biological farming systems, two conventional systems and one control treatment were compared. The experimental site contained a Luvisol from loess under arable land. The earthworms were investigated by handsorting three times in 1990 and 1991 after beetroot and winterwheat. The main differences within the treatments were fertilization and plant-protection management. All treatments received the same crop-rotation and a similar soil cultivation. The input of organic matter was similar in the three organically manured treatments. Significantly higher earthworm biomass, earthworm densities and presence of anecic species were found in the biological plots than in the conventional and control plots in spring and autumn of 1991. The control plot (no fertilizer during 12 years) had a similar earthworm-population as the conventional treatments. Apparently, plant protection seems to be the main factor responsible for the differences between the treatments. Nicodrilus longus, N. nocturnus, N. caliginosus and Allolobophora rosea were the dominant earthworm species in all treatments.  相似文献   

The effects of eggshell calcium (Biomin H®) and its combinations with alfacalcidol (1α-hydroxyvitamin D3) and menaquinone-7 (vitamin K2) on ovariectomy-induced bone loss in a rat model of osteoporosis     

Radoslav Omelka  Monika Martiniakova  Karol Svik  Lukas Slovak  Juraj Payer  Ingrid Oppenbergerova  Veronika Kovacova  Martina Babikova  Marta Soltesova-Prnova 《Journal of animal physiology and animal nutrition》2021,105(2):336-344

The purpose of this study was to investigate the impact of eggshell calcium (Biomin H^® dietary supplement) and its combinations with alfacalcidol (1α-hydroxyvitamin D₃) and menaquinone-7 (vitamin K₂) on ovariectomy-induced bone loss in rats. Adult female rats (n = 48) were divided into 6 groups of 8 individuals each: sham-operated rats (SHAM); ovariectomized (OVX) rats untreated; OVX rats treated with Biomin H^® (BIO); OVX rats simultaneously receiving Biomin H^®, vitamin D₃ (BIO + D₃); OVX rats simultaneously treated with Biomin H^®, vitamin K₂ (BIO + K₂) and OVX rats treated with Biomin H^®, vitamin D₃, vitamin K₂ (BIO + D₃ + K₂) during 8 weeks. Biochemical parameters, bone mineral density (BMD), bone mineral content (BMC) and femoral bone microstructure were determined. Plasma calcium and phosphate were increased in BIO + D₃ and BIO + D₃ + K₂ groups as compared to OVX. Alkaline phosphatase was elevated in OVX, BIO versus SHAM, BIO + D₃ + K2 groups. When compared to OVX group, decreased urine deoxypyridinoline was observed in all treated groups and femoral BMD, BMC were higher in BIO, BIO + D₃, BIO + D₃ + K₂ groups. The BIO + K₂ rats had similar densitometrical values than OVX individuals. Microcomputed tomography revealed increased trabecular relative bone volume (due to an increase in trabecular number) in BIO + D₃, BIO + D₃ + K₂ as compared to OVX. The higher relative bone volume in BIO + D₃, BIO + D₃ + K₂ groups was also accompanied by an increase in bone surface. In the cortical bone, an enhanced periosteal bone apposition was identified in BIO, BIO + D₃, BIO + K₂, BIO + D₃ + K₂ groups. The rats from BIO + D₃ + K₂ group had a higher area of primary osteon's vascular canals. In BIO + D₃, BIO + K₂, BIO + D₃ + K₂ groups, an increased area of secondary osteons was determined in comparison with OVX. Our results indicate the beneficial effect of triple application of Biomin H^®, vitamin D₃, vitamin K₂, as well as simultaneous administration of Biomin H^®, vitamin D₃ on the inhibition of ovariectomy-induced bone loss in a rat model of osteoporosis.  相似文献