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Triterpene saponins from aerial parts of Medicago arabica L   总被引:3,自引:0,他引:3  
Eight major triterpene saponins have been isolated from the aerial parts of Medicago arabica and their structures elucidated by FAB-MS and NMR analysis. Three of them are new compounds and are identified as 3-O-(alpha-L-arabinopyranoside) bayogenin, 3-O-(alpha-L-arabinopyranosyl), 28-O-(beta-D-glucopyranoside) bayogenin, and 3-O-[alpha-L-arabinopyranosyl(1-->2)-beta-D-glucuronopyranosyl], 28-O-beta-D-glucopyranoside 2-beta-hydroxyoleanolic acid. Two saponins, identified as 3-O-(alpha-L-arabinopyranoside) hederagenin and 3-O-(alpha-L-arabinopyranosyl), 28-O-(beta-D-glucopyranoside) hederagenin are known compounds but not previously reported as saponin constituents of Medicago species, while three other saponins, being mono- and bidesmosides of hederagenin, have been previously isolated from roots of M. sativa.  相似文献   
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Sawdust and wood residues are considered to be stimulators of microbiological change in soil and could be used in post-arable sites designed for afforestation. In this study, we discuss changes in bacteria numbers within selected groups in relation to soil type (arable and forest) and method of sawdust application. Sawdust was spread along planting rows and mixed with the soil or put directly under roots of planted seedlings. Applying sawdust under the roots increased the number of cellulolytic bacteria in all experimental treatments. On post-arable soil, adding sawdust in rows increased the number of copiotrophic bacteria and reduced the number of fluorescent bacteria and actinomycetes (ACT). In control forest soils, the number of copiotrophic, oligotrophic and spore-forming bacteria decreased simultaneously with increased ACT in all treatments. The number of fluorescent bacteria increased when sawdust was applied on forest sites under planted trees and decreased when sawdust was spread in planting rows. Oligotrophic bacteria also decreased in the latter case. We present a list of bacteria identified by DNA – 16S rRNA gene sequences. Adding sawdust to arable soils significantly changed the quantitative and qualitative composition of microbial communities.  相似文献   
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Forest fragmentation has led to a decline in the population of many forest specialists, especially those with limited dispersal abilities. However, some of these species also occur in fragmented forests, and their response to fragmentation is crucial to understand the impact of this process in maintaining forest biodiversity. The objective of this study was to investigate the effects of habitat quality, quantity and configuration on the occurrence of Hazel Grouse as the model species. Studies were performed in the Carpathian Foothills (900?km2, 15?% forested). Between 2000 and 2010, Hazel Grouse were detected in 25 out of 53 forest patches with high repeatability over time. Among the indices of habitat quality, the most important factors were the presence of bilberries, clearings and pioneer trees. Greater number and length of valleys also had a positive effect on the occurrence of grouse. All habitat quantity and landscape configuration variables influenced the presence of grouse positively (related to forest connectivity) or negatively (related to forest isolation). Among the explanatory variables considered, habitat quantity and landscape variables were much more important in explaining the occurrence of Hazel Grouse than variables related to habitat quality. The study shows that habitat acreage and its connectivity are crucial for the conservation and management of Hazel Grouse populations in fragmented landscapes, and therefore, it is necessary to sustain wooded corridors between larger forest patches.  相似文献   
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Tropospheric ozone and black carbon (BC) contribute to both degraded air quality and global warming. We considered ~400 emission control measures to reduce these pollutants by using current technology and experience. We identified 14 measures targeting methane and BC emissions that reduce projected global mean warming ~0.5°C by 2050. This strategy avoids 0.7 to 4.7 million annual premature deaths from outdoor air pollution and increases annual crop yields by 30 to 135 million metric tons due to ozone reductions in 2030 and beyond. Benefits of methane emissions reductions are valued at $700 to $5000 per metric ton, which is well above typical marginal abatement costs (less than $250). The selected controls target different sources and influence climate on shorter time scales than those of carbon dioxide-reduction measures. Implementing both substantially reduces the risks of crossing the 2°C threshold.  相似文献   
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The aim of the study was to determine the changes in composition and physicochemical features (pH, density, thermostability and acidity) of mare colostrum and milk, and of protein fraction contribution (serum albumin, β-casein, γ-casein, α-lactalbumin, G class immunoglobulins) depending on lactation stage. The research material was colostrum and milk samples from 12 Arabian mares. Colostrum samples were collected within 2 h after parturition and milk samples were collected twice, in the 3rd and 6th weeks of lactation. The level of basic milk components decreased significantly (only lactose content increased) as compared to colostrum. Total bacteria count and somatic cell count decreased significantly with an increase in resistance and urea level. The changes observed were connected to differentiated contribution of particular protein fractions and their relative proportions. Lower levels of γ-casein (P ≤ 0.05), β-casein, serum albumin as well as α-lactalbumin were observed in colostrum as compared to those in milk. Any relationship between lactation stage and β-casein content was observed. Serum albumin and α-lactalbumin content increased in subsequent milkings. The level of G class immunoglobulins decreased significantly and its highest level was noted in colostrum. Any significant differences between the 3rd and 6th lactation weeks were obtained.  相似文献   
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In young Taenia saginata cysticerci the reactions for alkaline phosphatase (AlPh), acid phosphatase (AcPh), ATP-ases, succinic dehydrogenase (SDH) and lacto dehydrogenase (LDH) were mild. The reactions were concentrated in the walls of spiral canals (AlPh, SDH) and in the outer layer of the bladder (AlPh). The reactions were more intensive in older cysticerci. In these, the reaction of AlPh marked a network of blood vessels winding around the larva. In dying cysticerci the reactions for oxidative enzymes (SDH, LDH) were weaker but the activity of the hydrolytic enzymes (AlPh, AcPh) was increased. These findings suggest that histoenzymatic reactions may be helpful in determining the viability and the age of cysticerci. T. saginata cysticerci in sheep and goats provoked an early and intensive cellular reaction. The histopathological appearance of the cysticerci as they were destroyed in the abnormal hosts was similar to that of cysticerci localized in abnormal tissue of the natural host (e.g., lung of calves). Treatment with mebendazole caused an intensive infiltrative reaction against dying cysticerci and a degenerative process in the surrounding muscle tissue. The treatment with praziquantel provoked a weak infiltration around dead cysticerci and did not affect the muscle tissue. In both cases the remnants of T. saginata cysticerci disappeared very slowly.  相似文献   
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