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排序方式: 共有195条查询结果,搜索用时 15 毫秒
101.
102.
Antarctic climate cooling and terrestrial ecosystem response. 总被引:15,自引:0,他引:15
Peter T Doran John C Priscu W Berry Lyons John E Walsh Andrew G Fountain Diane M McKnight Daryl L Moorhead Ross A Virginia Diana H Wall Gary D Clow Christian H Fritsen Christopher P McKay Andrew N Parsons 《Nature》2002,415(6871):517-520
The average air temperature at the Earth's surface has increased by 0.06 degrees C per decade during the 20th century, and by 0.19 degrees C per decade from 1979 to 1998. Climate models generally predict amplified warming in polar regions, as observed in Antarctica's peninsula region over the second half of the 20th century. Although previous reports suggest slight recent continental warming, our spatial analysis of Antarctic meteorological data demonstrates a net cooling on the Antarctic continent between 1966 and 2000, particularly during summer and autumn. The McMurdo Dry Valleys have cooled by 0.7 degrees C per decade between 1986 and 2000, with similar pronounced seasonal trends. Summer cooling is particularly important to Antarctic terrestrial ecosystems that are poised at the interface of ice and water. Here we present data from the dry valleys representing evidence of rapid terrestrial ecosystem response to climate cooling in Antarctica, including decreased primary productivity of lakes (6-9% per year) and declining numbers of soil invertebrates (more than 10% per year). Continental Antarctic cooling, especially the seasonality of cooling, poses challenges to models of climate and ecosystem change. 相似文献
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Blindness and auditory impairment caused by loss of the sodium bicarbonate cotransporter NBC3 总被引:7,自引:0,他引:7
Bok D Galbraith G Lopez I Woodruff M Nusinowitz S BeltrandelRio H Huang W Zhao S Geske R Montgomery C Van Sligtenhorst I Friddle C Platt K Sparks MJ Pushkin A Abuladze N Ishiyama A Dukkipati R Liu W Kurtz I 《Nature genetics》2003,34(3):313-319
Normal sensory transduction requires the efficient disposal of acid (H+) generated by neuronal and sensory receptor activity. Multiple highly sensitive transport mechanisms have evolved in prokaryotic and eukaryotic organisms to maintain acidity within strict limits. It is currently assumed that the multiplicity of these processes provides a biological robustness. Here we report that the visual and auditory systems have a specific requirement for H+ disposal mediated by the sodium bicarbonate cotransporter NBC3 (refs. 7,8). Mice lacking NBC3 develop blindness and auditory impairment because of degeneration of sensory receptors in the eye and inner ear as in Usher syndrome. Our results indicate that in certain sensory organs, in which the requirement to transduce specific environmental signals with speed, sensitivity and reliability is paramount, the choice of the H+ disposal mechanism used is limited. 相似文献
105.
106.
Inactivation of the Wip1 phosphatase inhibits mammary tumorigenesis through p38 MAPK-mediated activation of the p16(Ink4a)-p19(Arf) pathway 总被引:1,自引:0,他引:1
Bulavin DV Phillips C Nannenga B Timofeev O Donehower LA Anderson CW Appella E Fornace AJ 《Nature genetics》2004,36(4):343-350
Modulation of tumor suppressor activities may provide new opportunities for cancer therapy. Here we show that disruption of the gene Ppm1d encoding Wip1 phosphatase activated the p53 and p16 (also called Ink4a)-p19 (also called ARF) pathways through p38 MAPK signaling and suppressed in vitro transformation of mouse embryo fibroblasts (MEFs) by oncogenes. Disruption of the gene Cdkn2a (encoding p16 and p19), but not of Trp53 (encoding p53), reconstituted cell transformation in Ppm1d-null MEFs. In vivo, deletion of Ppm1d in mice bearing mouse mammary tumor virus (MMTV) promoter-driven oncogenes Erbb2 (also called c-neu) or Hras1 impaired mammary carcinogenesis, whereas reduced expression of p16 and p19 by methylation-induced silencing or inactivation of p38 MAPK correlated with tumor appearance. We conclude that inactivation or depletion of the Wip1 phosphatase with resultant p38 MAPK activation suppresses tumor appearance by modulating the Cdkn2a tumor-suppressor locus. 相似文献
107.
108.
North TE Goessling W Walkley CR Lengerke C Kopani KR Lord AM Weber GJ Bowman TV Jang IH Grosser T Fitzgerald GA Daley GQ Orkin SH Zon LI 《Nature》2007,447(7147):1007-1011
109.
Anderson CA Boucher G Lees CW Franke A D'Amato M Taylor KD Lee JC Goyette P Imielinski M Latiano A Lagacé C Scott R Amininejad L Bumpstead S Baidoo L Baldassano RN Barclay M Bayless TM Brand S Büning C Colombel JF Denson LA De Vos M Dubinsky M Edwards C Ellinghaus D Fehrmann RS Floyd JA Florin T Franchimont D Franke L Georges M Glas J Glazer NL Guthery SL Haritunians T Hayward NK Hugot JP Jobin G Laukens D Lawrance I Lémann M Levine A Libioulle C Louis E McGovern DP Milla M Montgomery GW 《Nature genetics》2011,43(3):246-252
Genome-wide association studies and candidate gene studies in ulcerative colitis have identified 18 susceptibility loci. We conducted a meta-analysis of six ulcerative colitis genome-wide association study datasets, comprising 6,687 cases and 19,718 controls, and followed up the top association signals in 9,628 cases and 12,917 controls. We identified 29 additional risk loci (P < 5 × 10(-8)), increasing the number of ulcerative colitis-associated loci to 47. After annotating associated regions using GRAIL, expression quantitative trait loci data and correlations with non-synonymous SNPs, we identified many candidate genes that provide potentially important insights into disease pathogenesis, including IL1R2, IL8RA-IL8RB, IL7R, IL12B, DAP, PRDM1, JAK2, IRF5, GNA12 and LSP1. The total number of confirmed inflammatory bowel disease risk loci is now 99, including a minimum of 28 shared association signals between Crohn's disease and ulcerative colitis. 相似文献
110.
C 3 and C 4 Species Changes Identified by δ 13 C values of soil organic matter in a Colorado prairie
We measured carbon isotope signatures (δ 13 C) from 0-10 cm and 10-20 cm soil depth intervals for grassland soils near Boulder, Colorado. These grasslands included tall-, short-, and mixed-grass prairies that were grazed, ungrazed, or hayed. Soils exhibited δ 13 C signatures consistent with observations that current sites are a mix of C 3 and C 4 species, with C 3 plants more abundant in mixed-grass than in native tall- or shortgrass prairies. The δ 13 C signatures were not significantly different for grassland types; however, management treatments (grazing, no grazing, haying) significantly influenced changes in soil δ 13 C signatures from the 0-10 cm to 10-20 cm soil depth intervals. We observed a correlation ( r = 0.63) between isotopic values of surface soils and percent native species in total vegetation cover. Overall, the community type with the lowest percentage of nonindigenous species cover had the most enriched δ 13 C signature. Sites currently grazed by prairie dogs, cattle, or both herbivores had stronger C 3 signatures, indicating that grazing may have increased C 3 plant productivity in these communities at the expense of C 4 grasses. This finding differs from studies of native shortgrass steppe where grazing has the opposite effect on the relative abundance of these 2 functional groups of plants. This result, along with the correlation between C 3 isotopic values and nonnative vegetation abundance, provides evidence that management practices that maintain dominance of C 4 grasses should be encouraged. 相似文献