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J.-M. Séquaris H. Philipp H.-D. Narres & H. Vereecken 《European Journal of Soil Science》2008,59(3):592-599
The decrease of NMR visibility of the C signal in soil samples due to the association between organic carbon (OC) and the topsoil mineral surface was investigated. CPMAS 13C‐NMR spectra were obtained for soil particle‐size fractions (< 2 μm, 2–20 μm, > 20 μm) and bulk soils from an agricultural topsoil (Chernozem) that had received three different amendments (no fertilization, mineral fertilization (NPK), mineral (NPK) and organic (cattle manure) fertilizations) at Bad Lauchstädt, Germany. The soil organic carbon content of the three soils depended on the degree of soil fertilization. There was no constant relationship between the total NMR signal intensity and the total amount of organic carbon (TOC) for all size fractions. Indeed, a key role played in the C signal intensity by the paramagnetic ferric ion from the clay content in soil fractions and bulk soils was confirmed. Thus, we describe the variations of C signal intensity by taking into account the distribution of clay‐associated OC and non‐associated OC pools. Depending on the amendment, the C signal visibility was weakened by a factor of 2–4 for the clay‐associated OC. This estimation was rendered possible by combining mineral specific surface area (SSA) measurements with the N2 gas adsorption method (BET method) and determination of TOC and iron concentrations. This approach contributes to the quantitative evaluation of the CPMAS 13C‐NMR detection. 相似文献
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Najla Mezghani Holly Ruess Neji Tarchoun Jihene Ben Amor Philipp W. Simon David M. Spooner 《Genetic Resources and Crop Evolution》2018,65(5):1359-1368
Tunisia, other countries in northwestern Africa, and the Iberian Peninsula, represent a center of diversity of Daucus. The genus traditionally has included about 20–25 species worldwide, but a recent molecular study redefined and expanded Daucus to include representatives from nine other genera. By this classification, Daucus now contains about 40 species, with some of them having winged fruits in addition to its traditionally recognized spiny fruits. The taxonomy of Daucus in Tunisia has recently been studied with morphological data, concluding that D. carota subsp. capillifolius is a subspecies that co-occurs and crosses with subsp. carota. The present study extends these findings with additional data from Genotyping-by-Sequencing (GBS) from 33 Tunisian accessions of D. carota (93 individuals with two to three replicates per accession), including the first collections of subsp. gummifer from Tunisia. Placed in the context of additional GBS data, D. carota subsp. gummifer has separate origins from other collections of subsp. carota in Tunisia and/or immediately adjacent areas to the north in Italy or its surrounding islands. Our results add support to the utility of large SNP datasets for species-level phylogenetic studies in Daucus. 相似文献
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Wang CJ Tas BM Glindemann T Mueller K Schiborra A Schoenbach P Gierus M Taube F Susenbeth A 《Journal of animal physiology and animal nutrition》2009,93(2):245-252
The aim of this study was to compare the effects of rotational and continuous grazing on herbage mass (HM), organic matter digestibility (dOM) and intake (OMI) and live weight gain (LWG) of sheep grazing on the inner Mongolian steppe, China at a stocking rate of 4.5 sheep/ha during the growing season. In the years 2005 and 2006, four 2-ha plots were used of which two were divided into four 0.5 ha paddocks each for rotational grazing, where sheep were moved each 10 days to the next paddock. The dOM was estimated from faecal crude protein concentration and OMI by oral administration of titanium dioxide. Herbage mass was similar in both grazing systems and dOM and OMI were higher (p < 0.05) at continuous grazing than at rotational grazing, but LWG did not differ probably because of extra energy expenditure for grazing and walking in a larger area. The dOM and OMI decreased (p < 0.05) with progress of the growing season and differed between years. Since precipitation during the growing season in both years was lower than the 30 years average which was probably the reason that positive effects of non-grazing periods on herbage regrowth and quality at rotational grazing could not occur, further studies are required in years with average precipitations before a final evaluation of these grazing systems can be made. Moreover, it seems necessary to quantify energy expenditure for physical activity of animals in grazing studies. 相似文献
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Tineke Slootweg Michel Alvinerie Philipp Egeler Daniel Gilberg Jussi V. K. Kukkonen Jörg Oehlmann Carsten Prasse Arto J. Sormunen Markus Liebig 《Journal of Soils and Sediments》2010,10(8):1611-1622
Purpose
Although ivermectin is a widely used lipophilic parasiticide, data on its potential bioaccumulation in aquatic invertebrates are scarce. In this study, bioaccumulation patterns of radiolabeled 3H-ivermectin from sediments into tissues of the sediment-dwelling worm Lumbriculus variegatus were investigated and assessed. 相似文献39.
Wilkins AL Rehmann N Torgersen T Rundberget T Keogh M Petersen D Hess P Rise F Miles CO 《Journal of agricultural and food chemistry》2006,54(15):5672-5678
Pectenotoxins from marine dinoflagellates of the genus Dinophysis are rapidly hydrolyzed by many shellfish to give pectenotoxin-2 seco acid, which isomerizes to 7-epi-pectenotoxin-2 seco acid. Three series of fatty acid esters of pectenotoxin-2 seco acid (PTX-2 seco acid) and 7-epi-PTX-2 seco acid were detected by LC-MS analysis of extracts from blue mussels (Mytilus edulis) from Ireland. The locations of the fatty acid ester linkages were identified by a combination of LC-MSn in positive- and negative-ion modes, LC-MS analysis of the products from reaction of the esters with sodium periodate, and NMR analysis of purified samples of the two most abundant ester derivatives. The 37-O-acyl esters of PTX-2 seco acid were the most abundant, followed by the corresponding 11-O-acyl esters, accompanied by low levels of the 33-O-acyl esters. The most abundant fatty acid esters in the fractionated sample were, in order, the 16:0, 22:6, 14:0, 16:1, 18:4, and 20:5 fatty acids, although a wide array of other PTX-2 seco acid fatty acid esters were also present at low levels. 相似文献
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T Jauffrais J Kilcoyne V Séchet C Herrenknecht P Truquet F Hervé JB Bérard C Nulty S Taylor U Tillmann CO Miles P Hess 《Marine drugs》2012,10(6):1360-1382
Azaspiracid (AZA) poisoning has been reported following consumption of contaminated shellfish, and is of human health concern. Hence, it is important to have sustainable amounts of the causative toxins available for toxicological studies and for instrument calibration in monitoring programs, without having to rely on natural toxin events. Continuous pilot scale culturing was carried out to evaluate the feasibility of AZA production using Azadinium spinosum cultures. Algae were harvested using tangential flow filtration or continuous centrifugation. AZAs were extracted using solid phase extraction (SPE) procedures, and subsequently purified. When coupling two stirred photobioreactors in series, cell concentrations reached 190,000 and 210,000 cell · mL(-1) at steady state in bioreactors 1 and 2, respectively. The AZA cell quota decreased as the dilution rate increased from 0.15 to 0.3 day(-1), with optimum toxin production at 0.25 day(-1). After optimization, SPE procedures allowed for the recovery of 79 ± 9% of AZAs. The preparative isolation procedure previously developed for shellfish was optimized for algal extracts, such that only four steps were necessary to obtain purified AZA1 and -2. A purification efficiency of more than 70% was achieved, and isolation from 1200 L of culture yielded 9.3 mg of AZA1 and 2.2 mg of AZA2 of >95% purity. This work demonstrated the feasibility of sustainably producing AZA1 and -2 from A. spinosum cultures. 相似文献