目次

Editorials

量子ベイズ主義(QBism)は、検証可能で現実的な応用の可能性を持つ量子力学の新たな捉え方である。

Be here now p.399

Growth in yields of the cereal must double if the Green Revolution is to be put back on track.

doi: 10.1038/507399a

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食糧需要の増大に対処するため、コムギの生産性の大幅な改善を目指す研究が必要だ。

Wheat lag p.399

New views of quantum theory that can be tested and have practical applications bring welcome echoes of physics past.

doi: 10.1038/507399b

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イタリアは、古代遺跡を守るため、防げる問題からすぐに取り組みを始めるべきだ。

A parlous state p.400

The decay at ancient Pompeii is symbolic of a deeper malaise in Italy’s heritage.

doi: 10.1038/507400a

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News

米国では大麻の使用が合法化された州があるにもかかわらず、官僚主義の弊害で、その研究にはいまだに厳しい制限が。

Federal red tape ties up marijuana research p.407

Despite drug’s legalization in two US states, biomedical science faces continued restrictions.

doi: 10.1038/507407a

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NASAのさまざまな探査計画が、延長を狙って予算獲得の競り合いに。

NASA missions bid for extensions p.409

Scientists must show projects’ potential to secure funding.

doi: 10.1038/507409a

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米最高裁のソフトウェア特許審理が始まり、結果に注目が。

Software patents await legal fate p.410

Supreme Court ruling could affect medical-diagnostics firms.

doi: 10.1038/507410a

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ポンペイ遺跡の劣化が進んでいるが、その対策として類似の遺跡、ヘルクラネウムがヒントに。

Sister city inspires Pompeii rescue p.411

Archaeologists hope that funding and conservation boost can halt decay of ancient city.

doi: 10.1038/507411a

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チリ政府が、前大統領の打ち出した科学省の新設構想を見直しへ。

Chile puts plan for science ministry on hold p.412

Government rethinks former president’s bid to create first unified science department.

doi: 10.1038/507412a

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News Features

人類の進化:内なるネアンデルタール人

Human evolution: The Neanderthal in the family p.414

古代DNAの研究が可能になって30年が経ち、その進歩が、歴史の書き換えに大いに役立っている。

doi: 10.1038/507414a

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免疫学:寛容なやり方

Immunology: A tolerant approach p.418

自己免疫疾患の標的治療の開発は長く失敗を繰り返しているが、その流れを変えようと研究が続けられている。

doi: 10.1038/507418a

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News & Views

神経科学:視覚情報アップデートについての新しい見方

Neuroscience: Updating views of visual updating p.434

我々の脳は、辺りをさっと見回しているときでも、安定な外界像を造り出す。脳が目の動きを補償する仕組みについての研究から、視界を安定させる機構に予想外の方式が使われていることが明らかになった。

doi: 10.1038/507434a

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太陽系:未知の領域に取り残される

Solar System: Stranded in no-man's-land p.435

太陽系の「内オールト雲」と呼ばれる領域に存在する二番目の天体が見つかった。このことは、巨大惑星と長い公転周期を持つ彗星の故郷との間にあるこの未知の領域について、新たな考察を促すものだ。

doi: 10.1038/507435a

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生物地球化学:メタン放出はシンプルな規則に従う

Biogeochemistry: Methane minimalism p.436

生態系レベルでのメタン放出についてのメタ解析から、メタン放出は複雑な多数の要因によって制御されているにもかかわらず、温度に依存する単純な指数曲線を描くことが分かった。

doi: 10.1038/nature13215

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気候科学:エルニーニョの予測は難しい

Climate science: A high bar for decadal forecasts of El Niño p.437

気候シミュレーションから、熱帯太平洋でのエルニーニョ・南方振動と呼ばれる現象には数十年の周期を持つ大小の変動があり、全く予測不能である可能性が示唆された。

doi: 10.1038/507437a

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アルツハイマー病:老化しつつある脳を守る因子

Alzheimer's disease: A protective factor for the ageing brain p.439

老化した脳を神経変性から防御している因子はどんなものなのだろうか。高齢者では、RESTというタンパク質が老化したニューロンの細胞死を防いだり、認知能力を維持したりするのに中心的な役割を果たしていることが明らかになった。

doi: 10.1038/nature13214

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低温物理学:低温下でのカオス

Low-temperature physics: Chaos in the cold p.440

理論と実験を組み合わせて、レーザー光で捕捉され、磁場中に置かれた極低温のエルビウム原子が、量子カオスの特徴を持つ衝突を起こすことが示された。

doi: 10.1038/nature13211

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骨関節炎:結び付けるのは亜鉛

Osteoarthritis: The zinc link p.441

軟骨組織を作っている軟骨細胞中への亜鉛の取り込みが増大すると、マトリックスを破壊する酵素が活性化されて、骨関節炎で見られる軟骨の破壊が引き起こされることが明らかになった。

doi: 10.1038/507441a

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Perspective

情報技術:プライバシーの究極的な物理的限界

The ultimate physical limits of privacy p.443

Among those who make a living from the science of secrecy, worry and paranoia are just signs of professionalism. Can we protect our secrets against those who wield superior technological powers? Can we trust those who provide us with tools for protection? Can we even trust ourselves, our own freedom of choice? Recent developments in quantum cryptography show that some of these questions can be addressed and discussed in precise and operational terms, suggesting that privacy is indeed possible under surprisingly weak assumptions.

doi: 10.1038/nature13132

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Articles

神経科学:加齢とアルツハイマー病におけるRESTとストレス抵抗性

REST and stress resistance in ageing and Alzheimer’s disease p.448

REST, a developmental regulator, is markedly induced in human neurons during ageing but is lost in Alzheimer’s disease; REST represses genes that promote neurodegeneration, is neuroprotective in animal models, and is associated with cognitive preservation and longevity in humans.

doi: 10.1038/nature13163

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遺伝学:ヒトの細胞種と組織全体にわたる活性化エンハンサーアトラス

An atlas of active enhancers across human cell types and tissues p.455

Using the FANTOM5 CAGE expression atlas, the authors show that bidirectional capped RNAs are a signature feature of active enhancers and identify over 40,000 enhancer candidates from over 800 human cell and tissue samples across the whole human body.

doi: 10.1038/nature12787

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遺伝学:プロモーターレベルでの哺乳類発現アトラス

A promoter-level mammalian expression atlas p.462

A study from the FANTOM consortium using single-molecule cDNA sequencing of transcription start sites and their usage in human and mouse primary cells, cell lines and tissues reveals insights into the specificity and diversity of transcription patterns across different mammalian cell types.

doi: 10.1038/nature13182

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Letters

宇宙:80天文単位の近日点を持つセドナ類似天体

A Sedna-like body with a perihelion of 80 astronomical units p.471

The observable Solar System can be divided into three distinct regions: the rocky terrestrial planets including the asteroids at 0.39 to 4.2 astronomical units (au) from the Sun (where 1 au is the mean distance between Earth and the Sun), the gas giant planets at 5 to 30 au from the Sun, and the icy Kuiper belt objects at 30 to 50 au from the Sun. The 1,000-kilometre-diameter dwarf planet Sedna was discovered ten years ago and was unique in that its closest approach to the Sun (perihelion) is 76 au, far greater than that of any other Solar System body. Formation models indicate that Sedna could be a link between the Kuiper belt objects and the hypothesized outer Oort cloud at around 10,000 au from the Sun. Here we report the presence of a second Sedna-like object, 2012 VP113, whose perihelion is 80 au. The detection of 2012 VP113 confirms that Sedna is not an isolated object; instead, both bodies may be members of the inner Oort cloud, whose objects could outnumber all other dynamically stable populations in the Solar System.

doi: 10.1038/nature13156

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低温物理学:気相エルビウム原子の極低温衝突における量子カオス

Quantum chaos in ultracold collisions of gas-phase erbium atoms p.475

Atomic and molecular samples reduced to temperatures below one microkelvin, yet still in the gas phase, afford unprecedented energy resolution in probing and manipulating the interactions between their constituent particles. As a result of this resolution, atoms can be made to scatter resonantly on demand, through the precise control of a magnetic field. For simple atoms, such as alkalis, scattering resonances are extremely well characterized. However, ultracold physics is now poised to enter a new regime, where much more complex species can be cooled and studied, including magnetic lanthanide atoms and even molecules. For molecules, it has been speculated that a dense set of resonances in ultracold collision cross-sections will probably exhibit essentially random fluctuations, much as the observed energy spectra of nuclear scattering do. According to the Bohigas–Giannoni–Schmit conjecture, such fluctuations would imply chaotic dynamics of the underlying classical motion driving the collision. This would necessitate new ways of looking at the fundamental interactions in ultracold atomic and molecular systems, as well as perhaps new chaos-driven states of ultracold matter. Here we describe the experimental demonstration that random spectra are indeed found at ultralow temperatures. In the experiment, an ultracold gas of erbium atoms is shown to exhibit many Fano–Feshbach resonances, of the order of three per gauss for bosons. Analysis of their statistics verifies that their distribution of nearest-neighbour spacings is what one would expect from random matrix theory. The density and statistics of these resonances are explained by fully quantum mechanical scattering calculations that locate their origin in the anisotropy of the atoms’ potential energy surface. Our results therefore reveal chaotic behaviour in the native interaction between ultracold atoms.

doi: 10.1038/nature13137

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気候科学:海洋の弱光層における炭素収支の調整

Reconciliation of the carbon budget in the ocean’s twilight zone p.480

Photosynthesis in the surface ocean produces approximately 100 gigatonnes of organic carbon per year, of which 5 to 15 per cent is exported to the deep ocean. The rate at which the sinking carbon is converted into carbon dioxide by heterotrophic organisms at depth is important in controlling oceanic carbon storage. It remains uncertain, however, to what extent surface ocean carbon supply meets the demand of water-column biota; the discrepancy between known carbon sources and sinks is as much as two orders of magnitude. Here we present field measurements, respiration rate estimates and a steady-state model that allow us to balance carbon sources and sinks to within observational uncertainties at the Porcupine Abyssal Plain site in the eastern North Atlantic Ocean. We find that prokaryotes are responsible for 70 to 92 per cent of the estimated remineralization in the twilight zone (depths of 50 to 1,000 metres) despite the fact that much of the organic carbon is exported in the form of large, fast-sinking particles accessible to larger zooplankton. We suggest that this occurs because zooplankton fragment and ingest half of the fast-sinking particles, of which more than 30 per cent may be released as suspended and slowly sinking matter, stimulating the deep-ocean microbial loop. The synergy between microbes and zooplankton in the twilight zone is important to our understanding of the processes controlling the oceanic carbon sink.

doi: 10.1038/nature13123

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地球:地球磁場変動が地球の核最上部の安定成層構造を明らかにする

Geomagnetic fluctuations reveal stable stratification at the top of the Earth’s core p.484

Modern observations of the geomagnetic field reveal fluctuations with a dominant period of about 60 years. These fluctuations are probably a result of waves in the liquid core, although the precise nature of the waves is uncertain. Common suggestions include a type of magnetic wave, known as a torsional oscillation, but recent studies favour periods that are too short to account for a 60-year fluctuation. Another possibility involves MAC waves, which arise from the interplay between magnetic, Archimedes and Coriolis forces. Waves with a suitable period can emerge when the top of the core is stably stratified. Here I show that MAC waves provide a good description of time-dependent zonal flow at the top of the core, as inferred from geomagnetic secular variation. The same wave motion can also account for unexplained fluctuations in the dipole field. Both of these independent predictions require a 140-kilometre-thick stratified layer with a buoyancy frequency comparable to the Earth’s rotation rate. Such a stratified layer could have a thermal origin, implying a core heat flow of about 13 terawatts. Alternatively, the layer could result from chemical stratification. In either case, the existence of a stratified layer at the top of the core obscures the nature of flow deeper in the core, where the magnetic field is continually regenerated.

doi: 10.1038/nature13122

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気候科学:メタンフラックスは微生物規模から生態系規模まで一貫した温度依存性を示す

Methane fluxes show consistent temperature dependence across microbial to ecosystem scales p.488

Methane (CH4) is an important greenhouse gas because it has 25 times the global warming potential of carbon dioxide (CO2) by mass over a century. Recent calculations suggest that atmospheric CH4 emissions have been responsible for approximately 20% of Earth’s warming since pre-industrial times. Understanding how CH4 emissions from ecosystems will respond to expected increases in global temperature is therefore fundamental to predicting whether the carbon cycle will mitigate or accelerate climate change. Methanogenesis is the terminal step in the remineralization of organic matter and is carried out by strictly anaerobic Archaea. Like most other forms of metabolism, methanogenesis is temperature-dependent. However, it is not yet known how this physiological response combines with other biotic processes (for example, methanotrophy, substrate supply, microbial community composition) and abiotic processes (for example, water-table depth) to determine the temperature dependence of ecosystem-level CH4 emissions. It is also not known whether CH4 emissions at the ecosystem level have a fundamentally different temperature dependence than other key fluxes in the carbon cycle, such as photosynthesis and respiration. Here we use meta-analyses to show that seasonal variations in CH4 emissions from a wide range of ecosystems exhibit an average temperature dependence similar to that of CH4 production derived from pure cultures of methanogens and anaerobic microbial communities. This average temperature dependence (0.96 electron volts (eV)), which corresponds to a 57-fold increase between 0 and 30°C, is considerably higher than previously observed for respiration (approximately 0.65 eV) and photosynthesis (approximately 0.3 eV). As a result, we show that both the emission of CH4 and the ratio of CH4 to CO2 emissions increase markedly with seasonal increases in temperature. Our findings suggest that global warming may have a large impact on the relative contributions of CO2 and CH4 to total greenhouse gas emissions from aquatic ecosystems, terrestrial wetlands and rice paddies.

doi: 10.1038/nature13164

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気候科学:種の生息域移行の地理的限界は気候変動の速度によって示唆される

Geographical limits to species-range shifts are suggested by climate velocity p.492

The reorganization of patterns of species diversity driven by anthropogenic climate change, and the consequences for humans, are not yet fully understood or appreciated. Nevertheless, changes in climate conditions are useful for predicting shifts in species distributions at global and local scales. Here we use the velocity of climate change to derive spatial trajectories for climatic niches from 1960 to 2009 (ref. 7) and from 2006 to 2100, and use the properties of these trajectories to infer changes in species distributions. Coastlines act as barriers and locally cooler areas act as attractors for trajectories, creating source and sink areas for local climatic conditions. Climate source areas indicate where locally novel conditions are not connected to areas where similar climates previously occurred, and are thereby inaccessible to climate migrants tracking isotherms: 16% of global surface area for 1960 to 2009, and 34% of ocean for the ‘business as usual’ climate scenario (representative concentration pathway (RCP) 8.5) representing continued use of fossil fuels without mitigation. Climate sink areas are where climate conditions locally disappear, potentially blocking the movement of climate migrants. Sink areas comprise 1.0% of ocean area and 3.6% of land and are prevalent on coasts and high ground. Using this approach to infer shifts in species distributions gives global and regional maps of the expected direction and rate of shifts of climate migrants, and suggests areas of potential loss of species richness.

doi: 10.1038/nature12976

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進化:カンブリア紀前期の懸濁物食性アノマロカリス類

A suspension-feeding anomalocarid from the Early Cambrian p.496

Large, actively swimming suspension feeders evolved several times in Earth’s history, arising independently from groups as diverse as sharks, rays and stem teleost fishes, and in mysticete whales. However, animals occupying this niche have not been identified from the early Palaeozoic era. Anomalocarids, a group of stem arthropods that were the largest nektonic animals of the Cambrian and Ordovician periods, are generally thought to have been apex predators. Here we describe new material from Tamisiocaris borealis, an anomalocarid from the Early Cambrian (Series 2) Sirius Passet Fauna of North Greenland, and propose that its frontal appendage is specialized for suspension feeding. The appendage bears long, slender and equally spaced ventral spines furnished with dense rows of long and fine auxiliary spines. This suggests that T. borealis was a microphagous suspension feeder, using its appendages for sweep-net capture of food items down to 0.5 mm, within the size range of mesozooplankton such as copepods. Our observations demonstrate that large, nektonic suspension feeders first evolved during the Cambrian explosion, as part of an adaptive radiation of anomalocarids. The presence of nektonic suspension feeders in the Early Cambrian, together with evidence for a diverse pelagic community containing phytoplankton and mesozooplankton, indicate the existence of a complex pelagic ecosystem supported by high primary productivity and nutrient flux. Cambrian pelagic ecosystems seem to have been more modern than previously believed.

doi: 10.1038/nature13010

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進化:原始的な板皮類から得られた、有顎脊椎動物の顔の起源に関する手がかり

A primitive placoderm sheds light on the origin of the jawed vertebrate face p.500

Extant vertebrates form two clades, the jawless Cyclostomata (lampreys and hagfishes) and the jawed Gnathostomata (all other vertebrates), with contrasting facial architectures. These arise during development from just a few key differences in the growth patterns of the cranial primordia: notably, the nasal sacs and hypophysis originate from a single placode in cyclostomes but from separate placodes in gnathostomes, and infraoptic ectomesenchyme migrates forward either side of the single placode in cyclostomes but between the placodes in gnathostomes. Fossil stem gnathostomes preserve cranial anatomies rich in landmarks that provide proxies for developmental processes and allow the transition from jawless to jawed vertebrates to be broken down into evolutionary steps. Here we use propagation phase contrast synchrotron microtomography to image the cranial anatomy of the primitive placoderm (jawed stem gnathostome) Romundina, and show that it combines jawed vertebrate architecture with cranial and cerebral proportions resembling those of cyclostomes and the galeaspid (jawless stem gnathostome) Shuyu. This combination seems to be primitive for jawed vertebrates, and suggests a decoupling between ectomesenchymal growth trajectory, ectomesenchymal proliferation, and cerebral shape change during the origin of gnathostomes.

doi: 10.1038/nature12980

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神経科学:視覚空間は眼球運動前に前前頭皮質で圧縮される

Visual space is compressed in prefrontal cortex before eye movements p.504

We experience the visual world through a series of saccadic eye movements, each one shifting our gaze to bring objects of interest to the fovea for further processing. Although such movements lead to frequent and substantial displacements of the retinal image, these displacements go unnoticed. It is widely assumed that a primary mechanism underlying this apparent stability is an anticipatory shifting of visual receptive fields (RFs) from their presaccadic to their postsaccadic locations before movement onset. Evidence of this predictive ‘remapping’ of RFs has been particularly apparent within brain structures involved in gaze control. However, critically absent among that evidence are detailed measurements of visual RFs before movement onset. Here we show that during saccade preparation, rather than remap, RFs of neurons in a prefrontal gaze control area massively converge towards the saccadic target. We mapped the visual RFs of prefrontal neurons during stable fixation and immediately before the onset of eye movements, using multi-electrode recordings in monkeys. Following movements from an initial fixation point to a target, RFs remained stationary in retinocentric space. However, in the period immediately before movement onset, RFs shifted by as much as 18 degrees of visual angle, and converged towards the target location. This convergence resulted in a threefold increase in the proportion of RFs responding to stimuli near the target region. In addition, like in human observers, the population of prefrontal neurons grossly mislocalized presaccadic stimuli as being closer to the target. Our results show that RF shifts do not predict the retinal displacements due to saccades, but instead reflect the overriding perception of target space during eye movements.

doi: 10.1038/nature13149

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がん:E3リガーゼCbl-bとTAM受容体はナチュラルキラー細胞を介してがん転移を調節する

The E3 ligase Cbl-b and TAM receptors regulate cancer metastasis via natural killer cells p.508

Tumour metastasis is the primary cause of mortality in cancer patients and remains the key challenge for cancer therapy. New therapeutic approaches to block inhibitory pathways of the immune system have renewed hopes for the utility of such therapies. Here we show that genetic deletion of the E3 ubiquitin ligase Cbl-b (casitas B-lineage lymphoma-b) or targeted inactivation of its E3 ligase activity licenses natural killer (NK) cells to spontaneously reject metastatic tumours. The TAM tyrosine kinase receptors Tyro3, Axl and Mer (also known as Mertk) were identified as ubiquitylation substrates for Cbl-b. Treatment of wild-type NK cells with a newly developed small molecule TAM kinase inhibitor conferred therapeutic potential, efficiently enhancing anti-metastatic NK cell activity in vivo. Oral or intraperitoneal administration using this TAM inhibitor markedly reduced murine mammary cancer and melanoma metastases dependent on NK cells. We further report that the anticoagulant warfarin exerts anti-metastatic activity in mice via Cbl-b/TAM receptors in NK cells, providing a molecular explanation for a 50-year-old puzzle in cancer biology. This novel TAM/Cbl-b inhibitory pathway shows that it might be possible to develop a ‘pill’ that awakens the innate immune system to kill cancer metastases.

doi: 10.1038/nature12998

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免疫:転写因子achaete-scute homologue 2は濾胞ヘルパーT細胞の発生を開始させる

Transcription factor achaete-scute homologue 2 initiates follicular T-helper-cell development p.513

In immune responses, activated T cells migrate to B-cell follicles and develop into follicular T-helper (TFH) cells, a recently identified subset of CD4+ T cells specialized in providing help to B lymphocytes in the induction of germinal centres. Although Bcl6 has been shown to be essential in TFH-cell function, it may not regulate the initial migration of T cells or the induction of the TFH program, as exemplified by C-X-C chemokine receptor type 5 (CXCR5) upregulation. Here we show that expression of achaete-scute homologue 2 (Ascl2)—a basic helix–loop–helix (bHLH) transcription factor—is selectively upregulated in TFH cells. Ectopic expression of Ascl2 upregulates CXCR5 but not Bcl6, and downregulates C-C chemokine receptor 7 (CCR7) expression in T cells in vitro, as well as accelerating T-cell migration to the follicles and TFH-cell development in vivo in mice. Genome-wide analysis indicates that Ascl2 directly regulates TFH-related genes whereas it inhibits expression of T-helper cell 1 (TH1) and TH17 signature genes. Acute deletion of Ascl2, as well as blockade of its function with the Id3 protein in CD4+ T cells, results in impaired TFH-cell development and germinal centre response. Conversely, mutation of Id3, known to cause antibody-mediated autoimmunity, greatly enhances TFH-cell generation. Thus, Ascl2 directly initiates TFH-cell development.

doi: 10.1038/nature12910

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生体材料:リンパ節を標的とする分子ワクチンの構造に基づくプログラミング

Structure-based programming of lymph-node targeting in molecular vaccines p.519

In cancer patients, visual identification of sentinel lymph nodes (LNs) is achieved by the injection of dyes that bind avidly to endogenous albumin, targeting these compounds to LNs, where they are efficiently filtered by resident phagocytes. Here we translate this ‘albumin hitchhiking’ approach to molecular vaccines, through the synthesis of amphiphiles (amph-vaccines) comprising an antigen or adjuvant cargo linked to a lipophilic albumin-binding tail by a solubility-promoting polar polymer chain. Administration of structurally optimized CpG-DNA/peptide amph-vaccines in mice resulted in marked increases in LN accumulation and decreased systemic dissemination relative to their parent compounds, leading to 30-fold increases in T-cell priming and enhanced anti-tumour efficacy while greatly reducing systemic toxicity. Amph-vaccines provide a simple, broadly applicable strategy to simultaneously increase the potency and safety of subunit vaccines.

doi: 10.1038/nature12978

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