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The Gulf Stream is a warm Atlantic current that transports heat northward, keeping Western Europe significantly warmer than North America in winter. It is known to influence short-term weather phenomena such as surface winds and cyclone formation, but its effects on longer-term climate and at higher levels in the atmosphere are poorly understood. Now a combination of weather analyses, satellite data and an atmospheric general circulation model reveals that the Gulf Streamãâãâs influence is felt well above the near-surface portion of the atmosphere. The current anchors a tall wall of atmospheric upward motion that penetrates into the upper troposphere and supports deep raining clouds. This provides a pathway by which the Gulf Stream can affect local climate, and possibly climate in remote regions via an effect on planetary wave propagation. The cover graphic represents surface current speeds in blue-white colours (white is the fastest) and upward wind velocities in yellow-red colours (red for stronger winds), along with land-surface topography in eastern North America. Cover graphic by F. Araki and S. Kawahara, ESC JAMSTEC
The fight against agricultural diseases in the United States has been boosted by fresh funds and a national monitoring network. But these advances are being undermined by inflexible bureaucracy.
It represents half of the world's rainforest and is home to one-third of Earth's species, yet the Amazon has one of the highest rates of deforestation. Jeff Tollefson looks at efforts to curb the problem.
Meteorologist and biosphere scientist Carlos Nobre of Brazil's National Institute for Space Research in São Paulo has modelled the effects of deforestation and global warming on the Amazon. Nature talks to him about the future of the unique rainforest.
Three teams are racing each other to build the next generation of telescopes that would dramatically dwarf the largest on Earth today. Eric Hand checks out the competition.
Huanglongbing, a disease that could devastate the US citrus industry, pits national security against plant pathologists looking to battle natural outbreaks, Ewen Callaway reports.
Parasitic worms kill many livestock, and the drugs used against them are becoming less effective. The discovery of a class of compounds that kills worms resistant to existing drugs is thus a welcome development.
The Universe seems to be expanding ever faster — a phenomenon generally ascribed to the influence of 'dark energy'. But might the observed acceleration be a trick of the light in an inhomogeneous Universe?
Many solids can adopt two mirror-image crystal forms, and often grow as mixtures of both. A curious mechanism of crystal growth might explain why some mixtures convert into one form when subjected to grinding.
Denitrifying bacteria and hungry plants do sterling work in disposing of the nitrates that we pump into rivers and streams. But as the excess influx goes up and up, the efficiency of removal goes down and down.
Many enzymes convert their substrates into organic radicals to allow challenging reactions to occur. A microbial enzyme does so by simple electron transfer, casting fresh light on enzyme evolution.
Earth's magnetic field is unstable. Not only does it vary in intensity, but from time to time it flips, with the poles reversing sign. Much of this behaviour remains a mystery, but a combination of geomagnetic observations with theoretical studies has been providing enlightenment.
The discovery of a new chemical class of anthelmintics that seem to act through a novel mechanism is reported. These small molecules are efficacious against various livestock pathogenic-nematode species.
A mechanism whereby the M2 isoform of the glycolytic enzyme pyruvate kinase (PKM2) can be regulated by tyrosine kinase signalling pathways through an ability to bind tyrosine-phosphorylated proteins is revealed.
SATB1 has been identified as a major regulator of gene expression in breast cancer. SATB1 is often overexpressed in breast tumours, correlating with poor prognosis, and altering the expression of many genes, which leads to enhanced tumourigenesis and metastasis.
In the standard model of terrestrial planet formation, interstellar grains of typical size ∼0.1 μm are expected to grow to millimetre, centimetre or even-metre sized objects rather quickly. Unfortunately, such evolved disks are hard to observe. This paper reports observations of grains that have grown to about millimetre-size or larger in the terrestrial zone of a 3 Myr old star.
DNA molecules have been programmed to fold into a basic structural unit, with four, twenty or sixty copies of that unit then assembling according to reaction conditions into either tetrahedra, dodecahedra or buckyballs, respectively. Other complex structures should also be accessible using this strategy.
About a quarter of the nitrogen added to the biosphere is exported from rivers to the ocean or inland basins, indicating substantial sinks for nitrogen must exist in the landscape. Data from nitrogen stable isotope tracer experiments across 72 streams suggests that the total uptake of nitrate is related to ecosystem photosynthesis, and that denitrification is related to ecosystem respiration. A stream network model demonstrates that excess nitrate in streams elicits a disproportionate increase in the fraction of nitrate that is exported to receiving waters and reduces the relative role of small versus large streams as nitrate sinks.
The Gulf Stream's influence on the atmosphere is examined using a combination of operational weather analyses and satellite observations. The results indicate that the Gulf Stream anchors a rain band in which upward motion of air penetrates deep into the upper troposphere, well above the near-surface portion of the atmosphere. These mechanisms provide a pathway by which the Gulf Stream can affect local climate, and possibly also climate in remote regions.
An investigation into the role of dispersal in determining diversity and productivity over evolutionary time scales using the bacterium Pseudomonas fluorescens shows that adaptive radiation driven by environmental heterogeneity and dispersal leads to the de novo evolution of a positive relationship between functional diversity and productivity, which both peak at intermediate dispersal rates.
In Arabidopsis, a map of methylated cytosines is generated at single base pair resolution by combining bisulphite treatment of genomic DNA with ultra-high-throughput sequencing.
Individual neurons at multiple stages of the visual system adapt to constant features in the visual scene, but how adaptation alters population dynamics is unknown. This paper shows that in the macaque primary visual cortex (V1), adaptation to briefly presented oriented stimuli alters pairwise correlations, with implications for the efficiency of the population code.
A microRNA (miR-203) that promotes differentiation of stratified epithelial stem cells by restricting their proliferation and inducing cell cycle exit is identified. One of its targets is p63, which regulates stem cells maintenance in skin, and it is shown that miR2-3 works by repressing p63 expression.
Many tumour cells express the M2 form of pyruvate kinase rather than the usual M1 form. PKM2 is now shown to promote tumorigenesis and switch the cellular metabolism to increased lactate production and reduced oxygen consumption, recapitulating key aspects of the Warburg effect.
The membrane protein UNC93B interacts with intracellular Toll-like receptors TLR7 and TLR9. This paper shows that UNC93B specifically controls TLR trafficking from the endoplasmic reticulum to the endolysosome but is not required for ligand recognition or signal initiation.
The pathogenic bacterium Clostridium difficile thrives by fermentation of L-leucine to ammonia, CO2, isovalerate, and isocaproate under anaerobic conditions. Ketyl radicals have been proposed to mediate a key reaction catalysed by an iron–sulphur cluster-containing dehydratase, which requires activation by ATP-dependent electron transfer from a second iron–sulphur protein. A kinetically competent product-related allylic ketyl radical bound to the dehydratase using electron paramagnetic resonance spectroscopy is identified. These results suggest that other 2-hydroxyacyl-CoA dehydratases (and the related benzoyl-CoA reductases) may employ ketyl radical intermediates. The absence of radical generators makes these enzymes unprecedented in biochemistry.
Artificially tethering a chromosomal region to the inner nuclear membrane (INM) of mammalian cells results in repression of gene transcription in conjunction with accumulation of lamin and INM proteins, but not nuclear pore complexes, at the tethered region.