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排序方式: 共有1338条查询结果,搜索用时 46 毫秒
921.
Barra A Garau VL Dessi S Sarais G Cereti E Arlorio M Coisson JD Cabras P 《Journal of agricultural and food chemistry》2008,56(22):10847-10852
The chemical composition of the Sardinian botargo by Mugil cephalus from different geographical origins was investigated. Fat ( approximately 20%), proteins ( approximately 50%), moisture ( approximately 22%), and salt ( approximately 7%) were measured in ground (G) and whole (W) commercial products. Among the nutritional compounds, omega-3 fatty acids were approximately 8%, squalene was approximately 15 mg/100 g, vitamin E was approximately 8.5 mg/kg, and cholesterol was approximately 300 mg/100 g, on average in both products. Antioxidant properties, assessed by the 1,1-diphenyl-2-picryl-hydrazyl (DPPH) test and expressed as Trolox equivalent antioxidant capacity (TEAC), showed quite good activity in extracted oil (0.8-1.1 mmol of Tolox/L). Major constituents in the samples varied noticeably, but only few statistical differences were evidenced between G or W products or between samples from different origins. Principal component analysis (PCA) of random amplified polymorphic DNA (RAPD) and proteins, coupled with both, did not differentiate samples from different origins. On the basis of our results, chemical and molecular data exclude the differentiation of samples from diverse origins. 相似文献
922.
Responses of proton release to phosphorus (P) availability by nodulated roots of common bean (Phaseolus vulgaris L.) were investigated for lines BAT 477 and CocoT, inoculated with Rhizobium tropici CIAT 899 in hydroaeroponic culture under glasshouse conditions. Phosphorus was supplied as KH2PO4 at 15 and 60 μmol plant–1 week–1 (15P and 60P). Proton release was higher for BAT 477 than for CocoT under both P supplies. However, it was higher for 60P than 15P, whatever the line. The ratio of proton release per unit biomass of nodulated root was higher for BAT 477 than for CocoT, independent of P deficiency. Proton release was correlated with the nodulated‐root respiration for both genotypes and with the nodule respiration linked with nitrogen fixation for CocoT. Thus, the nodulation was more limited by 15P than root and shoot growth and more in CocoT than in BAT 477. It is concluded that independent of symbiotic N2 fixation, proton release was higher in BAT 477 than in CocoT and that the nodulated legume releases a substantial amount of protons into its rhizosphere that is correlated with its nitrogen fixation that eventually depends upon the nodule permeability to O2 diffusion. 相似文献
923.
Ilya Yevdokimov Andreas Gattinger Franz Buegger Jean Charles Munch Michael Schloter 《Biology and Fertility of Soils》2008,44(8):1103-1106
The changes in size, activity and structure of soil microbial community caused by N fertilization were studied in a laboratory
incubation experiment. The rates of N fertiliser applied (KNO3) were 0 (control), 100 and 2,000 μg N g−1 soil. Despite no extra C sources added, a high percentage of N was immobilized. Whereas no significant increase of microbial
C was revealed during incubation period, microbial growth kinetics as determined by the substrate-induced growth-response
method demonstrated a significant decrease in the specific growth rate of microbial community in soil treated with 2,000 μg
N g−1 soil. Additionally, a shift in microbial community structure resulting in an increase in fungal biomarkers, mainly in the
treatment with 2,000 μg N g−1 soil was visible. 相似文献
924.
Enrique Alarcn-Gutirrez Carine Floch Christopher Augur Jean Le Petit Fabio Ziarelli Stven Criquet 《Pedobiologia》2009,52(6):387-399
Litter decomposition on the forest floor is an essential process in soil nutrient cycles and formation. These processes are controlled by abiotic factors such as climate and chemical litter quality, and by biotic factors such as microbial community diversity and activity. The aim of this study was to investigate the importance of litter depth with respect to (i) chemical litter quality as evaluated by solid-state 13C NMR, (ii) enzyme activities, and (iii) microbial functional diversity in four different litter layers (OLn, OLv, OF, and OH). A Mediterranean soil profile under an evergreen oak (Quercus ilex L.) forest was used as a model. The recalcitrant OM fraction, corresponding to the deepest layer, showed low enzyme activities. Peroxidases and fluorescein diacetate hydrolases (FDA) were more active in the OLn layer and probably originated largely from plants. High cellulase activity in the OLn and the OLv layers, which are rich in polysaccharides, corresponded with the high content of O-alkyl carbon compounds. Following polysaccharide degradation, laccases and lipases were much more evident in the intermediate layers. This spatial variation in nutrient demand reflected a preferential degradation of the specific plant polymers. Phosphatases were more active along the three upper layers and probably reflected a P limitation during litter degradation. Alkaline/acid (AcPAlP/AcP) ratio increased in the deepest layer, suggesting an increased participation of bacteria AlP in phosphatase pools. Results of BiologTM also indicated spatial variations in microbial functionality. Indeed, FF plates showed the highest functional diversity in the uppermost layer, while ECO plate functional diversity was highest in the intermediate layers. Finally, our results indicated that microbial activity and functional diversity of micro-organisms change with litter depth on a very small scale and vary with chemical organic matter (OM) composition. Thus, the observed increases in the biological variables studied were determined by the evolution of OM chemical structures, the nature and availability in C nutrients, and they ultimately resulted in a progressive accumulation of recalcitrant compounds. 相似文献
925.
Bastiaan Notebaert Gert Verstraeten Tom Rommens Bart Vanmontfort Gerard Govers Jean Poesen 《CATENA》2009
A Holocene sediment budget was constructed for the 758 km2 Dijle catchment in the Belgian loess belt, in order to understand long-term sediment dynamics. Hillslope sediment redistribution was calculated using soil profile information from 809 soil augerings, which was extrapolated to the entire catchment using morphometric classes. As large parts of the forests within the catchment prove to have undergone little or no erosion since medieval times, a correction was applied for the presence of forests. Total Holocene erosion amounts 817 ± 66 Mt for the catchment, of which 327 ± 34 Mt was deposited as colluvium. This corresponds with a net Holocene soil erosion rate of 10.8 ± 0.8 × 103 Mg ha− 1 for the entire Dijle catchment. Alluvial deposits were studied through 187 augerings spread over 17 cross-valley transects. The total alluvial sediment deposition equals 352 ± 11 Mt or 42% of total eroded sediment mass. Results indicate that at the scale of a medium-sized catchment the colluvial sediment sink is as important as the alluvial sediment sink and should not be neglected. As a result the estimation of erosion through alluvial storage and sediment export would yield large errors. Dating of sediment units show an important increase in alluvial deposition from medieval times onwards, indicating the important influence of agricultural activities that developed from that period. Mean sediment export rates from the catchment for the last 1000–1200 years range between 0.8 and 1.3 Mg ha− 1 a− 1 and are consistent with present suspended sediment measurements in the Dijle. Erosion for agricultural land for this period is 9.2 ± 2.2 Mg ha− 1 a− 1. Sediment budgets for the various tributary catchments provide an insight in the sources and sinks of sediment at different scales within the catchment. 相似文献
926.
The Brazilian Atlantic Forest: How much is left, and how is the remaining forest distributed? Implications for conservation 总被引:6,自引:0,他引:6
Milton Cezar Ribeiro Jean Paul Metzger Flávio Jorge Ponzoni 《Biological conservation》2009,142(6):1141-1153
The neotropical Atlantic Forest supports one of the highest degrees of species richness and rates of endemism on the planet, but has also undergone a huge forest loss. However, there exists no broad-scale information about the spatial distribution of its remnants that could guide conservation actions, especially when systematic biodiversity data are not available. In this context, our objectives were to quantify how much of the forest still remains, and analyze its spatial distribution. We considered the entire Brazilian Atlantic Forest, and eight sub-regions, defined according to species distribution. The results revealed a serious situation: more than 80% of the fragments are <50 ha, almost half the remaining forest is <100 m from its edges, the average distance between fragments is large (1440 m), and nature reserves protect only 9% of the remaining forest and 1% of the original forest. On the other hand, our estimates of existing Atlantic Forest cover were higher than previous ones (7-8%), ranging from 11.4% to 16%. The differences among estimates are mainly related to our inclusion of intermediate secondary forests and small fragments (<100 ha), which correspond to approximately 32-40% of what remains. We suggest some guidelines for conservation: (i) large mature forest fragments should be a conservation priority; (ii) smaller fragments can be managed in order to maintain functionally linked mosaics; (iii) the matrix surrounding fragments should be managed so as to minimize edge effects and improve connectivity; and (iv) restoration actions should be taken, particularly in certain key areas. The clear differences in the amount remaining and its spatial distribution within each sub-region must be considered when planning for biodiversity conservation. 相似文献
927.
928.
Elevated difenacoum metabolism is involved in the difenacoum‐resistant phenotype observed in Berkshire rats homozygous for the L120Q mutation in the vitamin K epoxide reductase complex subunit 1 (Vkorc1) gene
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Nolan Chatron Jean Valéry Debaux Etienne Benoit Virginie Lattard 《Pest management science》2018,74(6):1328-1334
929.
930.
Luciana Camacho-Pérez Jaime Martínez-Castillo Javier O. Mijangos-Cortés Miriam M. Ferrer-Ortega Jean Pierre Baudoin Rubén H. Andueza-Noh 《Genetic Resources and Crop Evolution》2018,65(1):229-241
Lima bean (Phaseolus lunatus L.) is an important crop in the Mayan culture. The Mayan area, considered as a main center of Mesoamerican diversity, has been divided into two subareas: the Mayan lowlands and the Mayan highlands. The Yucatan Peninsula is part of the Mayan lowlands and holds the highest number of Lima bean landraces of Mexico, but Lima beans are in high risk of genetic erosion due to intensification of the traditional Mayan agriculture. However, information on genetic diversity of Lima beans of the Mayan highlands is lacking. By using 46 landraces collected in the Mayan area (23 from each subarea) and 73 ISSR loci (inter-simple sequence repeats), we analyzed the structure, diversity and genetic relationships of Lima beans of this part of Mesoamerica. High levels of diversity (H BAY = 0.45) and genetic structure (F ST = 0.66) were found for the whole Mayan area. Genetic diversity in the Mayan lowlands was apparently higher than the Mayan highlands (H BAY = 0.44 and 0.36, respectively); but differences were not statistically significant. Genetic structure between the subareas was high (AMOVA = 30% of total variation), most landraces grouping according to their geographic origin. This study shows the importance of the Mayan culture in the diversification and conservation of Lima beans. The results provide important information that should be considered when implementing strategies to collect Lima bean landraces and planning in situ and ex situ programs to conserve these landraces in the Mayan region. 相似文献