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The cover shows a scanning electron micrograph of the spores or conidia of Aspergillus fumigatus (by S. Guadagnini, J. M. Panaud and A. Beauvais), one of the many fungal species contributing to the thousands of fungal spores that we inhale daily. The reason why these spores do not normally elicit an immune response has now been found, in the form of a hydrophobic layer of rodlet proteins covering the conidial surface.
The costs — both in animal lives and euros — of the European REACH legislation on chemical testing are escalating. Thomas Hartung and Costanza Rovida argue for a suspension of certain toxicity tests.
The US band They Might Be Giants has played rock to adults for more than two decades — and to children since 2002. Next week it releases the album Here Comes Science, with educational tunes about the elements and evolution. John Linnell, who fronts the band with John Flansburgh, explains why a science-friendly thread runs through their music.
Five studies show that disabling p53, an essential tumour-suppressor protein, improves the efficiency of stem-cell production. Are these results a 'heads up' that cancer cells and stem cells are disturbingly similar?
Evidence that the most recently discovered extrasolar planet is virtually at the end of its life is a surprise. The odds of that are very low — similar to drawing two consecutive red aces from a well-shuffled deck of cards.
Jumping genes, which make DNA copies of themselves through an RNA middleman, provide a stochastic process for generating brain diversity among humans. The effect of their random insertion, however, is a bit of a gamble.
A super-fast, lensless microscope has been developed that works by decoding the diffraction patterns of bright, laser-like flashes of X-rays. This advance should enable ultrafast events at the nanoscale to be recorded.
Certain insulators have conducting surfaces that arise from subtle chemical properties of the bulk material. The latest experiments suggest that such surfaces may compete with graphene in electronic applications.
The discovery of a short-lived γ-ray burst at a surprisingly early epoch in the history of the Universe shows how much is still unknown about the evolution of the parent systems of such bursts.
The contribution of changes in cis-regulatory elements or trans-acting factors to differences in gene expression between species is not well understood. Here it is found that, in transgenic mice containing the human β-globin locus, the expression of BCL11A differs between mouse and human and is a critical mediator of species-divergent globin switching.
'Hot Jupiters' abound in lists of known extrasolar planets. Those closest to their parent stars have strong tidal interactions, leading to the suggestion that systems such as OGLE-TR-56 could be used as tests of tidal dissipation theory. Here, the discovery of planet WASP-18b is reported, with an orbital period of 0.94 days and a tidal interaction an order of magnitude stronger than that of OGLE-TR-56b. Either WASP-18 is in a rare, short-lived state, or the tidal dissipation in this system must be weaker than in the Solar System.
Helical Dirac fermions are charge carriers that behave as massless relativistic particles with an intrinsic angular momentum (spin) locked to their translational momentum, a property desirable for spintronic and computing technologies. It has recently been proposed that such fermions may exist at the edges of certain types of topologically ordered insulators. Here, the realization and characterization of such a system is reported; the results reveal nearly 100 per cent spin polarization, even up to room temperature.
Topological insulators are materials in which a relativistic effect known as spin–orbit coupling gives rise to surface states that resemble chiral edge modes in quantum Hall systems, but with unconventional spin textures. It has been suggested that a feature of such spin-textured boundary states is their insensitivity to spin-independent scattering, which is thought to protect them from backscattering. Here, scanning tunnelling spectroscopy and angle-resolved photoemission spectroscopy are used to confirm this prediction.
Nanoplasmonics promises to revolutionize applications ranging from sensing and biomedicine to imaging and information technology, but its full development is hindered by the lack of devices that can generate coherent plasmonic fields. In theory, this is possible with a so-called 'spaser' — analogous to a laser — which would generate stimulated emission of surface plasmons. This is now realized experimentally, and should enable many new technological developments.
Temperature reconstructions for the surface of the Northern Hemisphere are based largely on terrestrial records from extra-tropical or high-elevation sites, despite the fact that global average surface temperature changes closely follow those of the global tropics, which are 75 per cent ocean. Here, a decadally resolved continuous sea surface temperature is reconstructed for the Indo-Pacific warm pool that spans the past 2,000 years, allowing for comparison with observations.
Fungal spores are ubiquitous in the air we breathe and contain many antigens and allergens, and yet they neither continuously activate the host innate immune cells nor induce detrimental inflammatory responses after their inhalation. Here, the surface layer on dormant spores is shown to mask their recognition by the immune system and hence prevent an immune response.
B cells migrate to the outer or centre lymphoid follicle at different stages of antibody responses. Here it is shown that activated B cells must downregulate the orphan G protein-coupled receptor EBI2 to migrate to the centre follicles, where they mount T dependent antibody responses and establish germinal centres.
Long interspersed element 1 (LINE-1 or L1) retrotransposons have been shown to move throughout the genomes of adult rat neural progenitor cells (NPCs) in vitro and in the mouse brain. Here, NPCs isolated from human fetal brain and derived from human embryonic stem cells are shown to support the retrotransposition of engineered human L1s in vitro, which could contribute to individual somatic mosaicism.
Induced pluripotent stem (iPS) cells are generated from mouse and human somatic cells by the introduction of four genes, but with low efficiency. Here it is reported that 10% of transduced mouse embryonic fibroblasts lacking p53 became iPS cells, even without the Myc retrovirus, and iPS cells were also generated from terminally differentiated T lymphocytes in the p53-null background.
The Ink4/Arf tumour suppressor locus encodes the three potent tumour suppressors p16Ink4a, p15Ink4b and p19Arf. Here the locus is shown to be rate-limiting for reprogramming, and its transient inhibition significantly improves the generation of induced pluripotent stem cells. Furthermore, ageing is shown to upregulate the Ink4/Arf locus, with less efficient reprogramming seen in cells from old organisms.
Expression of pluripotency factors and oncogenes can reprogram somatic cells to induced pluripotent stem cells, albeit with low frequency and a tendency to induce malignant transformation. Here, reprogramming factors are shown to activate the p53 pathway, providing insights into reprogramming mechanisms.
Pluripotency can be induced in somatic cells by overexpression of a set of transcription factors, but the process has extremely low efficiency and slow kinetics. Here, cells with low endogenous p19Arf levels and immortal fibroblasts deficient for components of the Arf–Trp53 pathway yield induced pluripotent stem cell colonies with up to threefold faster kinetics and at a significantly higher efficiency than wild-type cells, reaching frequencies of up to 100%.
It is shown that p53 is critically involved in preventing the reprogramming of cells carrying various types of DNA damage, including short telomeres, DNA repair deficiencies, or exogenously inflicted DNA damage. Eliminating p53 expression allows efficient reprogramming in the face of DNA damage and the generation of induced pluripotent stem cells carrying persistent DNA damage and chromosomal aberrations.
Here it is shown that PRDM16, a zinc finger protein that controls the switch from myoblastic precursors to brown fat cells, works together with C/EBP-β and that expression of this transcriptional unit is sufficient to induce a fully functional brown fat program in naive fibroblasts. Transplantation of such fibroblasts into mice creates a brown fat pad that acts as a sink for glucose.