Ancient biomolecules from deep ice cores reveal a forested southern Greenland   总被引：2，自引：0，他引：2  

Willerslev E  Cappellini E  Boomsma W  Nielsen R  Hebsgaard MB  Brand TB  Hofreiter M  Bunce M  Poinar HN  Dahl-Jensen D  Johnsen S  Steffensen JP  Bennike O  Schwenninger JL  Nathan R  Armitage S  de Hoog CJ  Alfimov V  Christl M  Beer J  Muscheler R  Barker J  Sharp M  Penkman KE  Haile J  Taberlet P  Gilbert MT  Casoli A  Campani E  Collins MJ 《Science (New York, N.Y.)》2007,317(5834):111-114

It is difficult to obtain fossil data from the 10% of Earth's terrestrial surface that is covered by thick glaciers and ice sheets, and hence, knowledge of the paleoenvironments of these regions has remained limited. We show that DNA and amino acids from buried organisms can be recovered from the basal sections of deep ice cores, enabling reconstructions of past flora and fauna. We show that high-altitude southern Greenland, currently lying below more than 2 kilometers of ice, was inhabited by a diverse array of conifer trees and insects within the past million years. The results provide direct evidence in support of a forested southern Greenland and suggest that many deep ice cores may contain genetic records of paleoenvironments in their basal sections.  相似文献   

A general synthetic procedure for heteropolyniobates     

Nyman M  Bonhomme F  Alam TM  Rodriguez MA  Cherry BR  Krumhansl JL  Nenoff TM  Sattler AM 《Science (New York, N.Y.)》2002,297(5583):996-998

The heteropolyanions of W, Mo, and V, which have found numerous applications, are formed simply by acidification of solutions of their oxoanions. Under similar conditions, these oxoanion precursors are not available for Nb, and Nb-oxo chemistry is dominated by formation of the Lindquist ion [Nb6O19]8- only. However, heteropolyniobate formation is favored in hydrothermal reactions of aqueous, alkaline precursor mixtures. Here we give two examples of heteropolyniobates formed by this general reaction type: K12[Ti2O2][SiNb12O40].16H2O [1], which contains chains of silicododecaniobate Keggin ions, and Na14[H2Si4Nb16O56].45.5H2O [2], a new heteropolyanion structure type.  相似文献   

Flavonoids possess neuroprotective effects on cultured pheochromocytoma PC12 cells: a comparison of different flavonoids in activating estrogenic effect and in preventing beta-amyloid-induced cell death     

Zhu JT  Choi RC  Chu GK  Cheung AW  Gao QT  Li J  Jiang ZY  Dong TT  Tsim KW 《Journal of agricultural and food chemistry》2007,55(6):2438-2445

Despite the classical hormonal effect, estrogen possesses a neuroprotective effect in the brain, which has led many to search for novel treatments for neurodegenerative diseases. Flavonoids, a group of compounds mainly derived from vegetables, share a resemblance, chemically, to estrogen, and indeed, some have been used as estrogen substitutes. To search for potential therapeutic agents against neurodegenerative diseases, different subclasses of flavonoids were analyzed and compared with estrogen. First, the estrogenic activities of these flavonoids were determined by activating the estrogen-responsive elements in cultured MCF-7 breast cancer cells. Second, the neuroprotective effects of flavonoids were revealed by measuring its inhibition effects on the formation of reactive oxygen species, the aggregation of beta-amyloid, and the induction of cell death by beta-amyloid in cultured neuronal PC12 cells. Among these flavonoids, baicalein, scutellarin, hibifolin, and quercetin-3'-glucoside possessed the strongest effect in neuroprotection; however, the neuroprotective activity did not directly correlate with the estrogenic activity of the flavonoids. Identification of these flavonoids could be very useful in finding potential drugs, or food supplements, for treating Alzheimer's disease.  相似文献   

Analysis of ITS of the rDNA to infer phylogenetic relationships among Vietnamese Citrus accessions   总被引：1，自引：0，他引：1  

Tina Kyndt  Tran Nhan Dung  Paul Goetghebeur  Ha Thanh Toan  Godelieve Gheysen 《Genetic Resources and Crop Evolution》2010,57(2):183-192

This study focused on clarifying phylogenetic relationships among Citrus accessions from Vietnam. Our phylogenetic analysis based on nucleotide sequences from the ITS of the ribosomal DNA included 69 accessions belonging to Citrus and related (sub)genera. Maximum parsimony and Bayesian analysis confirmed a clear separation of the three ‘true’ Citrus species (C. medica, C. maxima and C. reticulata). Confirming recent taxonomic revisions, Fortunella, Poncirus trifoliata and Citrus hystrix are clustered among the accessions of subgenus Citrus. C. × sinensis accessions revealed a close evolutionary relationship to either C. maxima or C. reticulata, thereby confirming their involvement in its hybrid origin. Also, some other hybrid taxa and their proposed parental species were investigated and their origin could in some cases be confirmed using the ITS sequence data.  相似文献   

Ultrasonic extraction of phenols from olive mill wastewater: comparison with conventional methods     

Jerman Klen T  Mozetič Vodopivec B 《Journal of agricultural and food chemistry》2011,59(24):12725-12731

Recovery of phenols from olive mill wastewater (OMWW) was studied, comparing five sample preparation methods: filtration, solid-phase (SPE), liquid-liquid (LLE) and ultrasonic (US)-assisted extraction of liquid and solid (freeze-dried) OMWW. Results showed that ultrasonication is a good alternative to conventional solvent extractions, providing higher recoveries at both levels of individual and total phenol yields. Sonication of liquid OMWW in organic solvent was more efficient vs its nonassisted counterpart (agitation), but did not provide a representative phenol chromatogram due to ethyl acetate use. By contrast, the US-assisted extraction of freeze-dried OMWW (3 × 20 min) in 100% methanol (1.5 g/25 mL, w/v) offered the highest qualitative-quantitative phenol yields without any US-induced alterations. Moreover, freeze-drying is an excellent preservation of initial liquid OMWW, holding a great potential for delayed analysis. This study is also the first report that Slovenian OMWW may be utilized as a valuable source of phenols, especially hydroxytyrosol and tyrosol.  相似文献   

Chemical and biological assessment of Angelicae Sinensis Radix after processing with wine: an orthogonal array design to reveal the optimized conditions     

Zhan JY  Zheng KY  Zhu KY  Bi CW  Zhang WL  Du CY  Fu Q  Dong TT  Choi RC  Tsim KW  Lau DT 《Journal of agricultural and food chemistry》2011,59(11):6091-6098

The roots of Angelica sinensis [Angelica Sinensis Radix (ASR)] have been used as a common health food supplement for women's care for thousands of years in China. According to Asian tradition, ASR could be processed with the treatment of wine, which subsequently promoted the biological functions of ASR. By chemical and biological assessments, an orthogonal array design was employed here to determine the roles of three variable parameters in the processing of ASR, including oven temperature, baking time, and flipping frequency. The results suggested that oven temperature and baking time were two significant factors, while flipping frequency was a subordinate factor. The optimized condition of processing with wine therefore was considered to be heating in an oven at 80 °C for 90 min with flipping twice per hour. Under the optimized processing conditions, the solubilities of ferulic acid and Z-ligustilide from ASR were markedly increased and decreased, respectively. In parallel, the biological functions of processed ASR were enhanced in both anti-platelet aggregation and estrogenic activation; these increased functions could be a result of the altered levels of ferulic acid and Z-ligustilide in wine-processed ASR. Thus, the chemical and biological assessment of the processed ASR was in full accordance with the Chinese old tradition.  相似文献   

Dyspnoea and pulmonary consolidation in a cat with T-cell lymphoma     

Brown AL  Beatty JA  Nicoll RG  Knight T  Krockenberger MB  Barrs VR 《Journal of Feline Medicine and Surgery》2011,13(10):772-775

A 13-year-old male neutered domestic shorthair cat presented with an acute onset of dyspnoea. Thoracic radiographs revealed marked, bilateral, caudal lung lobe consolidation. A diagnosis of anatomically mixed T-cell lymphoma with pulmonary, renal and alimentary involvement was confirmed on histopathology. Pulmonary involvement in cases of feline lymphoma is uncommon and the radiographic appearance of pulmonary lymphoma is highly variable. Lung lobe consolidation has been described with primary lung tumours in cats, but not previously in association with pulmonary lymphoma. This unusual presentation serves to alert practitioners to the possibility of lymphoma as a cause of severe bronchopulmonary disease in the cat.  相似文献   

Canine conjunctival mast cell tumors: a retrospective study     

Fife M  Blocker T  Fife T  Dubielzig RR  Dunn K 《Veterinary ophthalmology》2011,14(3):153-160

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Interaction between Notch and Hif-alpha in development and survival of Drosophila blood cells     

Mukherjee T  Kim WS  Mandal L  Banerjee U 《Science (New York, N.Y.)》2011,332(6034):1210-1213

A blood cell type termed crystal cell in Drosophila functions in clotting and wound healing and requires Notch for specification and maintenance. We report that crystal cells express elevated levels of Sima protein orthologous to mammalian hypoxia-inducible factor-α (Hif-α) even under conditions of normal oxygen availability. In these platelet-like crystal cells, Sima activates full-length Notch receptor signaling via a noncanonical, ligand-independent mechanism that promotes hemocyte survival during both normal hematopoietic development and hypoxic stress. This interaction initiates in early endosomes, is independent of Hif-β (Τangο in Drosophila), and does not activate hypoxia response targets. Studies in vertebrate myeloid cells have shown a similar up-regulation of Hif-α protein in well-oxygenated environments. This study provides a mechanistic paradigm for Hif-α/Notch interaction that may be conserved in mammals.  相似文献   

Worldwide phylogeography of wild boar reveals multiple centers of pig domestication   总被引：3，自引：0，他引：3  

Larson G  Dobney K  Albarella U  Fang M  Matisoo-Smith E  Robins J  Lowden S  Finlayson H  Brand T  Willerslev E  Rowley-Conwy P  Andersson L  Cooper A 《Science (New York, N.Y.)》2005,307(5715):1618-1621

Mitochondrial DNA (mtDNA) sequences from 686 wild and domestic pig specimens place the origin of wild boar in island Southeast Asia (ISEA), where they dispersed across Eurasia. Previous morphological and genetic evidence suggested pig domestication took place in a limited number of locations (principally the Near East and Far East). In contrast, new genetic data reveal multiple centers of domestication across Eurasia and that European, rather than Near Eastern, wild boar are the principal source of modern European domestic pigs.  相似文献