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Targeting early infection to prevent HIV-1 mucosal transmission

Nature 464, 217 (2010). doi:10.1038/nature08757

Authors: Ashley T. Haase

Measures to prevent sexual mucosal transmission of human immunodeficiency virus (HIV)-1 are urgently needed to curb the growth of the acquired immunodeficiency syndrome (AIDS) pandemic and ultimately bring it to an end. Studies in animal models and acute HIV-1 infection reviewed here reveal potential viral vulnerabilities at the mucosal portal of entry in the earliest stages of infection that might be most effectively targeted by vaccines and microbicides, thereby preventing acquisition and averting systemic infection, CD4 T-cell depletion and pathologies that otherwise rapidly ensue.

Immunology and the elusive AIDS vaccine

Nature 464, 224 (2010). doi:10.1038/nature08898

Authors: Herbert W. Virgin & Bruce D. Walker

Developing a human immunodeficiency virus (HIV) vaccine is critical to end the global acquired immunodeficiency syndrome (AIDS) epidemic, but many question whether this goal is achievable. Natural immunity is not protective, and despite immunogenicity of HIV vaccine candidates, human trials have exclusively yielded disappointing results. Nevertheless, there is an indication that success may be possible, but this will be dependent on understanding the antiviral immune response in unprecedented depth to identify and engineer the types of immunity required. Here we outline fundamental immunological questions that need to be answered to develop a protective HIV vaccine, and the immediate need to harness a much broader scientific community to achieve this goal.

Somatic sex identity is cell autonomous in the chicken

Nature 464, 237 (2010). doi:10.1038/nature08852

Authors: D. Zhao, D. McBride, S. Nandi, H. A. McQueen, M. J. McGrew, P. M. Hocking, P. D. Lewis, H. M. Sang & M. Clinton

In the mammalian model of sex determination, embryos are considered to be sexually indifferent until the transient action of a sex-determining gene initiates gonadal differentiation. Although this model is thought to apply to all vertebrates, this has yet to be established. Here we have examined

Confirmation of general relativity on large scales from weak lensing and galaxy velocities

Nature 464, 256 (2010). doi:10.1038/nature08857

Authors: Reinabelle Reyes, Rachel Mandelbaum, Uros Seljak, Tobias Baldauf, James E. Gunn, Lucas Lombriser & Robert E. Smith

Although general relativity underlies modern cosmology, its applicability on cosmological length scales has yet to be stringently tested. Such a test has recently been proposed, using a quantity, EG, that combines measures of large-scale gravitational lensing, galaxy clustering and structure growth rate. The combination is insensitive to ‘galaxy bias’ (the difference between the clustering of visible galaxies and invisible dark matter) and is thus robust to the uncertainty in this parameter. Modified theories of gravity generally predict values of EG different from the general relativistic prediction because, in these theories, the ‘gravitational slip’ (the difference between the two potentials that describe perturbations in the gravitational metric) is non-zero, which leads to changes in the growth of structure and the strength of the gravitational lensing effect. Here we report that EG = 0.39 ± 0.06 on length scales of tens of megaparsecs, in agreement with the general relativistic prediction of EG ≈ 0.4. The measured value excludes a model within the tensor–vector–scalar gravity theory, which modifies both Newtonian and Einstein gravity. However, the relatively large uncertainty still permits models within f(nature08857-m6jpg4561114) theory, which is an extension of general relativity. A fivefold decrease in uncertainty is needed to rule out these models.

Deviations from a uniform period spacing of gravity modes in a massive star

Nature 464, 259 (2010). doi:10.1038/nature08864

Authors: Pieter Degroote, Conny Aerts, Annie Baglin, Andrea Miglio, Maryline Briquet, Arlette Noels, Ewa Niemczura, Josefina Montalban, Steven Bloemen, Raquel Oreiro, Maja Vučković, Kristof Smolders, Michel Auvergne, Frederic Baudin, Claude Catala & Eric Michel

The life of a star is dominantly determined by the physical processes in the stellar interior. Unfortunately, we still have a poor understanding of how the stellar gas mixes near the stellar core, preventing precise predictions of stellar evolution. The unknown nature of the mixing processes as well as the extent of the central mixed region is particularly problematic for massive stars. Oscillations in stars with masses a few times that of the Sun offer a unique opportunity to disentangle the nature of various mixing processes, through the distinct signature they leave on period spacings in the gravity mode spectrum. Here we report the detection of numerous gravity modes in a young star with a mass of about seven solar masses. The mean period spacing allows us to estimate the extent of the convective core, and the clear periodic deviation from the mean constrains the location of the chemical transition zone to be at about 10 per cent of the radius and rules out a clear-cut profile.

Transmission of electrical signals by spin-wave interconversion in a magnetic insulator

Nature 464, 262 (2010). doi:10.1038/nature08876

Authors: Y. Kajiwara, K. Harii, S. Takahashi, J. Ohe, K. Uchida, M. Mizuguchi, H. Umezawa, H. Kawai, K. Ando, K. Takanashi, S. Maekawa & E. Saitoh

The energy bandgap of an insulator is large enough to prevent electron excitation and electrical conduction. But in addition to charge, an electron also has spin, and the collective motion of spin can propagate—and so transfer a signal—in some insulators. This motion is called a spin wave and is usually excited using magnetic fields. Here we show that a spin wave in an insulator can be generated and detected using spin-Hall effects, which enable the direct conversion of an electric signal into a spin wave, and its subsequent transmission through (and recovery from) an insulator over macroscopic distances. First, we show evidence for the transfer of spin angular momentum between an insulator magnet Y3Fe5O12 and a platinum film. This transfer allows direct conversion of an electric current in the platinum film to a spin wave in the Y3Fe5O12 via spin-Hall effects. Second, making use of the transfer in a Pt/Y3Fe5O12/Pt system, we demonstrate that an electric current in one metal film induces voltage in the other, far distant, metal film. Specifically, the applied electric current is converted into spin angular momentum owing to the spin-Hall effect in the first platinum film; the angular momentum is then carried by a spin wave in the insulating Y3Fe5O12 layer; at the distant platinum film, the spin angular momentum of the spin wave is converted back to an electric voltage. This effect can be switched on and off using a magnetic field. Weak spin damping in Y3Fe5O12 is responsible for its transparency for the transmission of spin angular momentum. This hybrid electrical transmission method potentially offers a means of innovative signal delivery in electrical circuits and devices.

Tunable polymer multi-shape memory effect

Nature 464, 267 (2010). doi:10.1038/nature08863

Authors: Tao Xie

Shape memory polymers are materials that can memorize temporary shapes and revert to their permanent shape upon exposure to an external stimulus such as heat, light, moisture or magnetic field. Such properties have enabled a variety of applications including deployable space structures, biomedical devices, adaptive optical devices, smart dry adhesives and fasteners. The ultimate potential for a shape memory polymer, however, is limited by the number of temporary shapes it can memorize in each shape memory cycle and the ability to tune the shape memory transition temperature(s) for the targeted applications. Currently known shape memory polymers are capable of memorizing one or two temporary shapes, corresponding to dual- and triple-shape memory effects (also counting the permanent shape), respectively. At the molecular level, the maximum number of temporary shapes a shape memory polymer can memorize correlates directly to the number of discrete reversible phase transitions (shape memory transitions) in the polymer. Intuitively, one might deduce that multi-shape memory effects are achievable simply by introducing additional reversible phase transitions. The task of synthesizing a polymer with more than two distinctive and strongly bonded reversible phases, however, is extremely challenging. Tuning shape memory effects, on the other hand, is often achieved through tailoring the shape memory transition temperatures, which requires alteration in the material composition. Here I show that the perfluorosulphonic acid ionomer (PFSA), which has only one broad reversible phase transition, exhibits dual-, triple-, and at least quadruple-shape memory effects, all highly tunable without any change to the material composition.

A large atomic chlorine source inferred from mid-continental reactive nitrogen chemistry

Nature 464, 271 (2010). doi:10.1038/nature08905

Authors: Joel A. Thornton, James P. Kercher, Theran P. Riedel, Nicholas L. Wagner, Julie Cozic, John S. Holloway, William P. Dubé, Glenn M. Wolfe, Patricia K. Quinn, Ann M. Middlebrook, Becky Alexander & Steven S. Brown

Halogen atoms and oxides are highly reactive and can profoundly affect atmospheric composition. Chlorine atoms can decrease the lifetimes of gaseous elemental mercury and hydrocarbons such as the greenhouse gas methane. Chlorine atoms also influence cycles that catalytically destroy or produce tropospheric ozone, a greenhouse gas potentially toxic to plant and animal life. Conversion of inorganic chloride into gaseous chlorine atom precursors within the troposphere is generally considered a coastal or marine air phenomenon. Here we report mid-continental observations of the chlorine atom precursor nitryl chloride at a distance of 1,400 km from the nearest coastline. We observe persistent and significant nitryl chloride production relative to the consumption of its nitrogen oxide precursors. Comparison of these findings to model predictions based on aerosol and precipitation composition data from long-term monitoring networks suggests nitryl chloride production in the contiguous USA alone is at a level similar to previous global estimates for coastal and marine regions. We also suggest that a significant fraction of tropospheric chlorine atoms may arise directly from anthropogenic pollutants.

Systematic genetic analysis of muscle morphogenesis and function in Drosophila

Nature 464, 287 (2010). doi:10.1038/nature08799

Authors: Frank Schnorrer, Cornelia Schönbauer, Christoph C. H. Langer, Georg Dietzl, Maria Novatchkova, Katharina Schernhuber, Michaela Fellner, Anna Azaryan, Martin Radolf, Alexander Stark, Krystyna Keleman & Barry J. Dickson

Systematic genetic approaches have provided deep insight into the molecular and cellular mechanisms that operate in simple unicellular organisms. For multicellular organisms, however, the pleiotropy of gene function has largely restricted such approaches to the study of early embryogenesis. With the availability of genome-wide transgenic RNA interference (RNAi) libraries in Drosophila, it is now possible to perform a systematic genetic dissection of any cell or tissue type at any stage of the lifespan. Here we apply these methods to define the genetic basis for formation and function of the Drosophila muscle. We identify a role in muscle for 2,785 genes, many of which we assign to specific functions in the organization of muscles, myofibrils or sarcomeres. Many of these genes are phylogenetically conserved, including genes implicated in mammalian sarcomere organization and human muscle diseases.

B-cell-derived lymphotoxin promotes castration-resistant prostate cancer

Nature 464, 302 (2010). doi:10.1038/nature08782

Authors: Massimo Ammirante, Jun-Li Luo, Sergei Grivennikov, Sergei Nedospasov & Michael Karin

Prostate cancer (CaP) progresses from prostatic intraepithelial neoplasia through locally invasive adenocarcinoma to castration-resistant metastatic carcinoma. Although radical prostatectomy, radiation and androgen ablation are effective therapies for androgen-dependent CaP, metastatic castration-resistant CaP is a major complication with high mortality. Androgens stimulate growth and survival of prostate epithelium and early CaP. Although most patients initially respond to androgen ablation, many develop castration-resistant CaP within 12–18 months. Despite extensive studies, the mechanisms underlying the emergence of castration-resistant CaP remain poorly understood and their elucidation is critical for developing improved therapies. Curiously, castration-resistant CaP remains androgen-receptor dependent, and potent androgen-receptor antagonists induce tumour regression in castrated mice. The role of inflammation in castration-resistant CaP has not been addressed, although it was reported that intrinsic NF-κB activation supports its growth. Inflammation is a localized protective reaction to injury or infection, but it also has a pathogenic role in many diseases, including cancer. Whereas acute inflammation is critical for host defence, chronic inflammation contributes to tumorigenesis and metastatic progression. The inflammation-responsive IκB kinase (IKK)-β and its target NF-κB have important tumour-promoting functions within malignant cells and inflammatory cells. The latter, including macrophages and lymphocytes, are important elements of the tumour microenvironment, but the mechanisms underlying their recruitment remain obscure, although they are thought to depend on chemokine and cytokine production. We found that CaP progression is associated with inflammatory infiltration and activation of IKK-α, which stimulates metastasis by an NF-κB-independent, cell autonomous mechanism. Here we show that androgen ablation causes infiltration of regressing androgen-dependent tumours with leukocytes, including B cells, in which IKK-β activation results in production of cytokines that activate IKK-α and STAT3 in CaP cells to enhance hormone-free survival.

Climate of fear

Nature 464, 141 (2010). doi:10.1038/464141a

The integrity of climate research has taken a very public battering in recent months. Scientists must now emphasize the science, while acknowledging that they are in a street fight.

Scientific glasnost

Nature 464, 141 (2010). doi:10.1038/464141b

Russia's scientific reputation will continue to dwindle unless it embraces international research.

Europe's research future

Nature 464, 142 (2010). doi:10.1038/464142a

The region's member states must follow through on their political and scientific commitments.

Palaeontology: The long and the short

Nature 464, 144 (2010). doi:10.1038/464144a

Zool. J. Linn. Soc.158, 477–500 (2010) 10.1111/j.1096-3642.2009.00562.xThe fossils of many arthropods — invertebrates with hard, external skeletons and segmented bodies — from 540 million to 250 million years ago have a large pair of 'great appendages' that

Metabolism: Warm milk

Nature 464, 144 (2010). doi:10.1038/464144b

Cell Metab.11, 206–212 (2010) 10.1016/j.cmet.2010.02.001Mother's milk fires up a heat-generating metabolic pathway in newborn mice.Newborns have to rapidly adjust to the comparatively chilly environment outside the womb. Francesc Villarroya of the University of Barcelona in Spain

Chemistry: Cellulose busters

Nature 464, 144 (2010). doi:10.1038/464144c

Neuroscience: Nerve cell talk

Nature 464, 144 (2010). doi:10.1038/464144d

Science327, 1250–1254 (2010) 10.1126/science.1184821Neuroscientists had long believed that neural cells called astrocytes (pictured) provide structural support and nutrients to the neurons they surround. But a debate has erupted over whether these cells also release signalling molecules that

Biomaterials: Squishy particles

Nature 464, 144 (2010). doi:10.1038/464144e

Cancer biology: Arsenic activation

Nature 464, 144 (2010). doi:10.1038/464144f

Cancer Res.70, 1981–1988 (2010) 10.1158/0008-5472.CAN-09-2898Arsenic, a carcinogen found at unsafe levels in drinking water in many parts of the world, may cause cancer by increasing the activity of the Hedgehog signalling pathway, which is known to promote

Physics: Photon storage for telecoms

Nature 464, 145 (2010). doi:10.1038/464145a

Phys. Rev. Lett.104, 080502 (2010) 10.1103/PhysRevLett.104.080502Photons have a quantum mechanical spin, which can be 'up', 'down' or both. Storing a photon using conventional methods alters this state, destroying its quantum information.Björn Lauritzen and his colleagues at the University