| 21. |
- Hilton, Robert G., et al.
(author)
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Erosion of organic carbon in the Arctic as a geological carbon dioxide sink
- 2015
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In: Nature. - : Springer Science and Business Media LLC. - 0028-0836 .- 1476-4687. ; 524:7563, s. 84-U162
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Journal article (peer-reviewed)abstract
- Soils of the northern high latitudes store carbon over millennial timescales (thousands of years) and contain approximately double the carbon stock of the atmosphere(1-3). Warming and associated permafrost thaw can expose soil organic carbon and result in mineralization and carbon dioxide (CO2) release(4-6). However, some of this soil organic carbon may be eroded and transferred to rivers(7-9). If it escapes degradation during river transport and is buried in marine sediments, then it can contribute to a longer-term (more than ten thousand years), geological CO2 sink(8-10). Despite this recognition, the erosional flux and fate of particulate organic carbon (POC) in large rivers at high latitudes remains poorly constrained. Here, we quantify the source of POC in the Mackenzie River, the main sediment supplier to the Arctic Ocean(11,12), and assess its flux and fate. We combine measurements of radiocarbon, stable carbon isotopes and element ratios to correct for rock-derived POC10,13,14. Our samples reveal that the eroded biospheric POC has resided in the basin for millennia, with a mean radiocarbon age of 5,800 +/- 800 years, much older than the POC in large tropical rivers(13,14). From the measured biospheric POC content and variability in annual sediment yield(15), we calculate a biospheric POC flux of 2.2(-0.9)(+1.3) teragrams of carbon per year from the Mackenzie River, which is three times the CO2 drawdown by silicate weathering in this basin(16). Offshore, we find evidence for efficient terrestrial organic carbon burial over the Holocene period, suggesting that erosion of organic carbon-rich, high-latitude soils may result in an important geological CO2 sink.
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| 22. |
- Holmes, EA
(author)
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THEATRE Performing rituals
- 2015
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In: NATURE. - : Springer Science and Business Media LLC. - 0028-0836 .- 1476-4687. ; 519:7543, s. 289-289
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Journal article (other academic/artistic)
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| 23. |
- Hoshino, Ayuko, et al.
(author)
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Tumour exosome integrins determine organotropic metastasis
- 2015
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In: Nature. - : NATURE PUBLISHING GROUP. - 0028-0836 .- 1476-4687. ; 527:7578, s. 329-
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Journal article (peer-reviewed)abstract
- Ever since Stephen Pagets 1889 hypothesis, metastatic organotropism has remained one of cancers greatest mysteries. Here we demonstrate that exosomes from mouse and human lung-, liver-and brain-tropic tumour cells fuse preferentially with resident cells at their predicted destination, namely lung fibroblasts and epithelial cells, liver Kupffer cells and brain endothelial cells. We show that tumour-derived exosomes uptaken by organ-specific cells prepare the pre-metastatic niche. Treatment with exosomes from lung-tropic models redirected the metastasis of bone-tropic tumour cells. Exosome proteomics revealed distinct integrin expression patterns, in which the exosomal integrins alpha(6)beta(4) and alpha(6)beta(1) were associated with lung metastasis, while exosomal integrin alpha(v)beta(5) was linked to liver metastasis. Targeting the integrins alpha(6)beta(4) and alpha(v)beta(5) decreased exosome uptake, as well as lung and liver metastasis, respectively. We demonstrate that exosome integrin uptake by resident cells activates Src phosphorylation and pro-inflammatory S100 gene expression. Finally, our clinical data indicate that exosomal integrins could be used to predict organ-specific metastasis.
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| 24. |
- Howes, L. M., et al.
(author)
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Extremely metal-poor stars from the cosmic dawn in the bulge of the Milky Way
- 2015
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In: Nature. - : Springer Science and Business Media LLC. - 0028-0836 .- 1476-4687. ; 527:7579, s. 484-487
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Journal article (peer-reviewed)abstract
- The first stars are predicted to have formed within 200 million years after the Big Bang(1), initiating the cosmic dawn. A true first star has not yet been discovered, although stars(2-4) with tiny amounts of elements heavier than helium ('metals') have been found in the outer regions ('halo') of the Milky Way. The first stars and their immediate successors should, however, preferentially be found today in the central regions ('bulges') of galaxies, because they formed in the largest over-densities that grew gravitationally with time(5,6). The Milky Way bulge underwent a rapid chemical enrichment during the first 1-2 billion years(7), leading to a dearth of early, metal-poor stars(8,9). Here we report observations of extremely metal-poor stars in the Milky Way bulge, including one star with an iron abundance about 10,000 times lower than the solar value without noticeable carbon enhancement. We confirm that most of the metal-poor bulge stars are on tight orbits around the Galactic Centre, rather than being halo stars passing through the bulge, as expected for stars formed at redshifts greater than 15. Their chemical compositions are in general similar to typical halo stars of the same metallicity although intriguing differences exist, including lower abundances of carbon.
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| 25. |
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| 26. |
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| 27. |
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| 28. |
- Joshi, Peter K, et al.
(author)
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Directional dominance on stature and cognition in diverse human populations
- 2015
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In: Nature. - : Springer Science and Business Media LLC. - 0028-0836 .- 1476-4687. ; 523:7561, s. 459-462
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Journal article (peer-reviewed)abstract
- Homozygosity has long been associated with rare, often devastating, Mendelian disorders, and Darwin was one of the first to recognize that inbreeding reduces evolutionary fitness. However, the effect of the more distant parental relatedness that is common in modern human populations is less well understood. Genomic data now allow us to investigate the effects of homozygosity on traits of public health importance by observing contiguous homozygous segments (runs of homozygosity), which are inferred to be homozygous along their complete length. Given the low levels of genome-wide homozygosity prevalent in most human populations, information is required on very large numbers of people to provide sufficient power. Here we use runs of homozygosity to study 16 health-related quantitative traits in 354,224 individuals from 102 cohorts, and find statistically significant associations between summed runs of homozygosity and four complex traits: height, forced expiratory lung volume in one second, general cognitive ability and educational attainment (P < 1 × 10(-300), 2.1 × 10(-6), 2.5 × 10(-10) and 1.8 × 10(-10), respectively). In each case, increased homozygosity was associated with decreased trait value, equivalent to the offspring of first cousins being 1.2 cm shorter and having 10 months' less education. Similar effect sizes were found across four continental groups and populations with different degrees of genome-wide homozygosity, providing evidence that homozygosity, rather than confounding, directly contributes to phenotypic variance. Contrary to earlier reports in substantially smaller samples, no evidence was seen of an influence of genome-wide homozygosity on blood pressure and low density lipoprotein cholesterol, or ten other cardio-metabolic traits. Since directional dominance is predicted for traits under directional evolutionary selection, this study provides evidence that increased stature and cognitive function have been positively selected in human evolution, whereas many important risk factors for late-onset complex diseases may not have been.
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