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111.
Valderas JM 《Science (New York, N.Y.)》2007,317(5844):1496-8; author reply 1496-8
112.
Solforosi L Criado JR McGavern DB Wirz S Sánchez-Alavez M Sugama S DeGiorgio LA Volpe BT Wiseman E Abalos G Masliah E Gilden D Oldstone MB Conti B Williamson RA 《Science (New York, N.Y.)》2004,303(5663):1514-1516
Neuronal death is a prominent, but poorly understood, pathological hallmark of prion disease. Notably, in the absence of the cellular prion protein (PrPC), the disease-associated isoform, PrPSc, appears not to be intrinsically neurotoxic, suggesting that PrPC itself may participate directly in the prion neurodegenerative cascade. Here, cross-linking PrPC in vivo with specific monoclonal antibodies was found to trigger rapid and extensive apoptosis in hippocampal and cerebellar neurons. These findings suggest that PrPC functions in the control of neuronal survival and provides a model to explore whether cross-linking of PrPC by oligomeric PrPSc can promote neuronal loss during prion infection. 相似文献
113.
Zdobnov EM von Mering C Letunic I Torrents D Suyama M Copley RR Christophides GK Thomasova D Holt RA Subramanian GM Mueller HM Dimopoulos G Law JH Wells MA Birney E Charlab R Halpern AL Kokoza E Kraft CL Lai Z Lewis S Louis C Barillas-Mury C Nusskern D Rubin GM Salzberg SL Sutton GG Topalis P Wides R Wincker P Yandell M Collins FH Ribeiro J Gelbart WM Kafatos FC Bork P 《Science (New York, N.Y.)》2002,298(5591):149-159
Comparison of the genomes and proteomes of the two diptera Anopheles gambiae and Drosophila melanogaster, which diverged about 250 million years ago, reveals considerable similarities. However, numerous differences are also observed; some of these must reflect the selection and subsequent adaptation associated with different ecologies and life strategies. Almost half of the genes in both genomes are interpreted as orthologs and show an average sequence identity of about 56%, which is slightly lower than that observed between the orthologs of the pufferfish and human (diverged about 450 million years ago). This indicates that these two insects diverged considerably faster than vertebrates. Aligned sequences reveal that orthologous genes have retained only half of their intron/exon structure, indicating that intron gains or losses have occurred at a rate of about one per gene per 125 million years. Chromosomal arms exhibit significant remnants of homology between the two species, although only 34% of the genes colocalize in small "microsyntenic" clusters, and major interarm transfers as well as intra-arm shuffling of gene order are detected. 相似文献
114.
Jiang J Jorda JL Yu J Baumes LA Mugnaioli E Diaz-Cabanas MJ Kolb U Corma A 《Science (New York, N.Y.)》2011,333(6046):1131-1134
The formation of mesopores in microporous zeolites is generally performed by postsynthesis acid, basic, and steam treatments. The hierarchical pore systems thus formed allow better adsorption, diffusion, and reactivity of these materials. By combining organic and inorganic structure-directing agents and high-throughput methodologies, we were able to synthesize a zeolite with a hierarchical system of micropores and mesopores, with channel openings delimited by 28 tetrahedral atoms. Its complex crystalline structure was solved with the use of automated diffraction tomography. 相似文献
115.
Moreira MM Carvalho AM Valente IM Goncalves LM Rodrigues JA Barros AA Guido LF 《Journal of agricultural and food chemistry》2011,59(14):7654-7658
This paper reports the development of a novel electrochemical assay for xanthohumol (XN) by square-wave adsorptive-stripping voltammetry (SWAdSV) with a hanging mercury drop electrode. The method showed good repeatability (CV < 2%) and linearity (between 10 and 250 μg L(-1)), as well as suitable limits of detection (2.6 μg L(-1)) and quantification (8.8 μg L(-1)). The method was applied for the quantification of this compound in spent hops, and the results obtained were compared with the HPLC-UV method. XN contents determined by the SWAdSV method were 16 ± 1 and 100 ± 4 μg L(-1) for aqueous and methanolic extracts, respectively. The developed new methodology considerably reduces the analysis time, approximately from 25 min (HPLC-UV method) to 7 min, enabling a high sample throughput. In addition, the detection and quantification limits were approximately 5-fold lower than those obtained with the chromatographic method. 相似文献
116.
Participatory landrace selection for on-farm conservation: An example from the Central Valleys of Oaxaca, Mexico 总被引:8,自引:1,他引:8
Mauricio R. Bellon Julien Berthaud Melinda Smale José Alfonso Aguirre Suketoshi Taba Flavio Aragón Jaime Díaz Humberto Castro 《Genetic Resources and Crop Evolution》2003,50(4):401-416
On-farm conservation is recognized as a key component of a comprehensive strategy to conserve crop genetic resources. A fundamental problem faced by any on-farm conservation project is the identification of crop populations on which efforts should be focused. This paper describes a method to identify a subset of landraces for further conservation efforts from a larger collection representing the diversity found in the Central Valleys of Oaxaca, Mexico. Mexico is a center of origin and diversity for maize (Zea mays L.). The 17 landraces selected from an initial collection of 152 satisfy two criteria. First, they represent the diversity present in the larger collection. Second, they appear to serve the interests of farmers in the region. Data for applying the method were elicited through participatory as well as conventional techniques. They incorporate the complementary perspectives of both men and women members of farm households, and of plant breeders and social scientists. 相似文献
117.
Gas chromatographic quantification of major volatile compounds and polyols in wine by direct injection 总被引:4,自引:0,他引:4
Peinado RA Moreno JA Muñoz D Medina M Moreno J 《Journal of agricultural and food chemistry》2004,52(21):6389-6393
Methanol, propanol, isobutanol, isoamyl alcohol, 2-phenylethanol, acetaldehyde, 1,1-diethoxyethane, acetoin, ethyl acetate, ethyl lactate, and ethyl succinate and the polyols 2,3-butanediol (levo and meso forms) and glycerol were quantified by direct injection of wine samples. Linear responses over the usual concentration ranges for these compounds and r2 values from 0.9932 to 0.9998 were obtained. The confidence limits for the mean values ranged from 2.34% for diethyl succinate to 8.52% for 1,1-diethoxyethane, both at a probability level of 0.05. Relative errors ranged from 8 to 10% for the polyols and 1,1-diethoxyethane and were all less than 5% for alcohols and acetaldehyde. The proposed method is useful with a view to identifying relationships between alcoholic fermentation byproducts and controlling biological or chemical aging in wines. 相似文献
118.
Jean-François Ponge Florence Dubs Jose Paulo Sousa 《Soil biology & biochemistry》2006,38(5):1158-1161
In previously published papers it had been demonstrated that at the local level the species richness of soil springtail communities was negatively influenced by landuse diversity. When the dispersal rate of soil animals was taken into account, quite opposite trends were displayed by species having poor or high dispersal capabilities. At the local level, species with short legs, non functional jumping apparatus and reduction of visual organs were distinguished against by landuse diversity, while species with long legs, functional jumping apparatus (furcula) and complete eyes, thus able to disperse at the soil surface, were not. It was verified, through aerial photographs taken 50 years ago, that landuse changes, expected to be more frequent in heterogeneous landscapes, may contribute to explain this phenomenon. 相似文献
119.
120.
Ranalli A Gomes T Delcuratolo D Contento S Lucera L 《Journal of agricultural and food chemistry》2003,51(9):2597-2602
Three major virgin olive oil varieties (Dritta, Leccino, and Coratina) extracted by a modern centrifugation system aided with a new plant enzyme preparation (having prevalently pectolytic activity) were characterized. These oils showed a clearly enhanced quality standard, owing to higher levels of some important minor components (phenolics, volatiles, tocopherols, carotenes, and chlorophylls) and to frequently lower concentrations of oxidized triglycerides and diglycerides. The oils were therefore characterized by lower susceptibility to oxidation and longer shelf life, and their flavor, aroma, and color features appeared to be significantly improved. The saponifiable fraction was practically not affected as the enzymatic effects involved only the membranes of the oil droplets, where the nonglyceridic compounds are essentially located. 相似文献