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The Amazon basin in transition 总被引:7,自引:0,他引:7
Davidson EA de Araújo AC Artaxo P Balch JK Brown IF C Bustamante MM Coe MT DeFries RS Keller M Longo M Munger JW Schroeder W Soares-Filho BS Souza CM Wofsy SC 《Nature》2012,481(7381):321-328
Agricultural expansion and climate variability have become important agents of disturbance in the Amazon basin. Recent studies have demonstrated considerable resilience of Amazonian forests to moderate annual drought, but they also show that interactions between deforestation, fire and drought potentially lead to losses of carbon storage and changes in regional precipitation patterns and river discharge. Although the basin-wide impacts of land use and drought may not yet surpass the magnitude of natural variability of hydrologic and biogeochemical cycles, there are some signs of a transition to a disturbance-dominated regime. These signs include changing energy and water cycles in the southern and eastern portions of the Amazon basin. 相似文献
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Wu X Northcott PA Dubuc A Dupuy AJ Shih DJ Witt H Croul S Bouffet E Fults DW Eberhart CG Garzia L Van Meter T Zagzag D Jabado N Schwartzentruber J Majewski J Scheetz TE Pfister SM Korshunov A Li XN Scherer SW Cho YJ Akagi K MacDonald TJ Koster J McCabe MG Sarver AL Collins VP Weiss WA Largaespada DA Collier LS Taylor MD 《Nature》2012,482(7386):529-533
Medulloblastoma, the most common malignant paediatric brain tumour, arises in the cerebellum and disseminates through the cerebrospinal fluid in the leptomeningeal space to coat the brain and spinal cord. Dissemination, a marker of poor prognosis, is found in up to 40% of children at diagnosis and in most children at the time of recurrence. Affected children therefore are treated with radiation to the entire developing brain and spinal cord, followed by high-dose chemotherapy, with the ensuing deleterious effects on the developing nervous system. The mechanisms of dissemination through the cerebrospinal fluid are poorly studied, and medulloblastoma metastases have been assumed to be biologically similar to the primary tumour. Here we show that in both mouse and human medulloblastoma, the metastases from an individual are extremely similar to each other but are divergent from the matched primary tumour. Clonal genetic events in the metastases can be demonstrated in a restricted subclone of the primary tumour, suggesting that only rare cells within the primary tumour have the ability to metastasize. Failure to account for the bicompartmental nature of metastatic medulloblastoma could be a major barrier to the development of effective targeted therapies. 相似文献
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Chromatin-modifying enzymes as modulators of reprogramming 总被引:2,自引:0,他引:2
Onder TT Kara N Cherry A Sinha AU Zhu N Bernt KM Cahan P Marcarci BO Unternaehrer J Gupta PB Lander ES Armstrong SA Daley GQ 《Nature》2012,483(7391):598-602
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S Neph J Vierstra AB Stergachis AP Reynolds E Haugen B Vernot RE Thurman S John R Sandstrom AK Johnson MT Maurano R Humbert E Rynes H Wang S Vong K Lee D Bates M Diegel V Roach D Dunn J Neri A Schafer RS Hansen T Kutyavin E Giste M Weaver T Canfield P Sabo M Zhang G Balasundaram R Byron MJ MacCoss JM Akey MA Bender M Groudine R Kaul JA Stamatoyannopoulos 《Nature》2012,489(7414):83-90