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81.
Salinas I Myklebust R Esteban MA Olsen RE Meseguer J Ringø E 《Veterinary microbiology》2008,128(1-2):167-177
Probiotic bacteria increase the host health status and protect mucosal tissue against pathogen-caused damage in mammalian models. Using an in vitro (intestinal sac) method this study aimed to address (a) the in vitro ability of Lactobacillus delbrueckii subsp. lactis to remain in the gastrointestinal tract of Atlantic salmon (Salmo salar L.) and (b) its ability to prevent cellular damage caused by successive incubation with Aeromonas salmonicida subsp. salmonicida the causative agent of furunculosis. Short in vitro incubation of salmon foregut with (TRITC)-labelled L. delbrueckii subsp. lactis showed that the probiont was able to colonize the enterocyte surface as studied by confocal microscopy. Furthermore, foregut incubated with the probiotic bacteria only, resulted in a healthy intestinal barrier whereas exposure to A. salmonicida disrupted its integrity. However, pre-treatment of salmon intestine with L. delbrueckii subsp. lactis prevented Aeromonas damaging effects. These results are promising in the context of the use of non-autochthonous probiotic bacteria as prophylactic agents against fish bacterial infections in the gastrointestinal tract. 相似文献
82.
The N‐deposition in Germany is commonly calculated as values of about 20—30 kg/ha·yr. This range is based on the measurements of the nitrate and ammonium nitrogen bulk deposition, which does not include the gaseous N‐deposition and the direct N‐uptake by plants. The calculation of airbone N‐deposition from N‐balances of the Static Fertilization Experiment Bad Lauchstädt came to 50—58 kg/ha·yr. This is consistent with results from other European long‐term experiments. Using the newly developed 15N‐based ITNI‐system, the total airborne N‐deposition can be determined. For Bad Lauchstädt analogous to results of former measuring periods an annual N‐deposition of 65 kg/ha·yr was measured in 1998, a figure greater than the balanced values. The balanced and measured values show, that airborne N‐deposition is often underestimated and amounts to at least 50 kg/ha·yr, which is a significant burden on natural ecosystems. By taking this extra N‐input into account in calculations for fertilizer recommendations in agriculture a decrease of N‐losses can be achieved which, in turn can also induce a decrease in airborne N‐deposition. 相似文献
83.
The chemical identity of organic nitrogen (N) containing compounds in soils is only partially known, because 20—35% of soil N can not be hydrolyzed and identified by wet‐chemical methods. Therefore a new methodology for investigations of the extractability and composition of nonhydrolyzed N was developed using a combination of selective extraction, wet‐chemical analyses and pyrolysis‐mass spectrometry. Residues of organic matter hydrolysis with 6 M HCl from particle‐size separates and whole soils of five sites in Thyrow, 2 × Halle, Lauterbach and Bad Lauchstädt (Germany) were treated with dithionite/citrate/bicarbonate (DCB) to remove pedogenic oxides and bound N‐containing compounds. Between 13 and 61% (mean 34 ± 13%) of nonhydrolyzed N (Nnhydr) was extracted with DCB. For all particle‐size separates, there was a close positive correlation between the contents of nonhydrolyzed N and DCB extractable Al and Fe, respectively. Univariate analysis of variance and Pearson correlation coefficients showed that the specific surface areas of samples were the major factor determining the contents of Nnhydr. About 30—50% of the variation in Nnhydr could be explained by the variation in the contents of pedogenic oxides. In the DCB extraction residues an additional portion of 12 to 66% of N was hydrolyzed by 6 M HCl. About 75% of total N in the DCB extracts was hydrolyzed, and 29% was identified as α‐amino‐N. Amino acid analysis showed that the DCB extracts from clay and fine silt contained all amino acids characteristic of soils. Pyrolysis‐field ionization mass spectrometry (Py‐FIMS) of a freeze‐dried DCB extract indicated the presence of peptides (about 5% of total ion intensity) and heterocyclic N‐containing compounds (about 3% of total ion intensity). In summary, these results provide evidence that organic‐mineral bonds at reactive surfaces (silicates, pedogenic oxides, alkali‐extractable organic substances) are the main factors for the nonhydrolyzability of significant amounts of organic N, including peptides. It is concluded that the processes of trapping and binding of proteinaceous compounds proceed as postulated for recent models of soil organic matter (SOM) and soil particles. Molecular mechanics calculations show large gaps between SOM and the mineral matrix and as well as fine pores and voids in SOM which have a strong potential to occlude and bind peptides (hydrogen bonds). 相似文献
84.
Modeling irrigated cotton with shallow groundwater in the Aral Sea Basin of Uzbekistan: I. Water dynamics 总被引:4,自引:3,他引:1
I. Forkutsa Rolf Sommer Y. I. Shirokova J. P. A. Lamers K. Kienzler B. Tischbein C. Martius P. L. G. Vlek 《Irrigation Science》2009,27(4):331-346
In Khorezm, a region located in the Aral Sea basin of Uzbekistan, water use for irrigation of predominantly cotton is high
whereas water use efficiency is low. To quantify the seasonal water and salt balance, water application, crop growth, soil
water, and groundwater dynamics were studied on a sandy, sandy loam and loamy cotton field in the years 2003 and 2005. To
simulate and quantify improved management strategies and update irrigation standards, the soil water model Hydrus-1D was applied.
Results showed that shallow groundwater contributed a substantial share (up to 399 mm) to actual evapotranspiration of cotton
(estimated at 488–727 mm), which alleviated water stress in response to suboptimal quantities of water applied for irrigation,
but enhanced concurrently secondary soil salinization. Thus, pre-season salt leaching becomes a necessity. Nevertheless, as
long as farmers face high uncertainty in irrigation water supply, maintaining shallow groundwater tables can be considered
as a safety-net against unreliable water delivery. Simulations showed that in 2003 around 200 mm would have been sufficient
during pre-season leaching, whereas up to 300 mm of water was applied in reality amounting to an overuse of almost 33%. Using
some of this water during the irrigation season would have alleviated season crop-water stress such as in June 2003. Management
strategy analyses revealed that crop water uptake would only marginally benefit from a permanent crop residue layer, often
recommended as part of conservation agriculture. Such a mulch layer, however, would substantially reduce soil evaporation,
capillary rise of groundwater, and consequently secondary soil salinization. The simulations furthermore demonstrated that
not relying on the contribution of shallow groundwater to satisfy crop water demand is possible by implementing timely and
soil-specific irrigation scheduling. Water use would then not be higher than the current Uzbek irrigation standards. It is
argued that if furrow irrigation is to be continued, pure sandy soils, which constitute <5% of the agricultural soils in Khorezm,
are best to be taken out of annual cotton production. 相似文献
85.
Moazzami AA Andersson RE Kamal-Eldin A 《Journal of agricultural and food chemistry》2006,54(3):633-638
An HPLC method was developed and validated for the quantification of sesaminol triglucoside and a sesaminol diglucoside in sesame seeds. These two lignans were isolated, and their structures were characterized by mass and nuclear magnetic resonance spectroscopy. Defatted sesame flour was extracted first with 85% ethanol for 5 h followed by 70% ethanol for 10 h at room temperature using naringenin as internal standard. Analysis of 65 different samples of sesame seeds indicated that the content of sesaminol triglucoside ranged from 36 to 1560 mg/100 g of seed (mean 637 +/- 312) and that of sesaminol diglucoside ranged from 0 to 493 mg/100 g of seed (mean 75 +/- 95). No significant difference was found between sesaminol glucoside contents in black and white seeds. 相似文献
86.
Lösel D Lacorn M Büttner D Claus R 《Journal of agricultural and food chemistry》2006,54(16):5990-5995
Skatole originates from microbial processing of tryptophan in the large intestine of pigs and accumulates in adipose tissue. Formation may be inhibited by the anti-apoptotic function of butyrate formed out of raw potato starch. Two groups of pigs (each consisting of gilts and barrows) were fed from 30 to 110 kg life weight either a conventional diet (controls; n = 35) or an isocaloric diet containing 300 g of raw potato starch/kg of body weight (RS; n = 34). Skatole concentrations were measured in colon content, blood, and adipose tissue. Odor of cooked meat samples was evaluated by a test panel. RS reduced concentrations in colon content and blood plasma (P < 0.001). Back fat concentrations were decreased significantly from 25 to 1.40 ng/g (barrows; P < 0.001) and from 40 to 9 ng/g (gilts; P < 0.001). Odor rating (scale of 1-5 from very unpleasant to very pleasant) was 3.07 for low skatole concentrations and 2.66 for both medium and high skatole concentrations (P < 0.05). 相似文献
87.
The effect of diurnal variations in air humidity and temperature under continuous lighting period (LP) on growth, flowering and water loss were studied in two pot-rose cultivars. 相似文献
88.
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