目次

Editorials

米国の科学分野の資金状況は悪化しており、科学予算の「横ばい」という虚構にだまされてはならない。

Don’t hide the decline p.139

US scientists should not be placated by the ‘flat budget’ myth. Funds are decreasing, and the situation will get worse.

doi: 10.1038/507139a

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生態学には普遍的理論はないが、それが生態学の魅力でもある。

An elegant chaos p.139

Universal theories are few and far between in ecology, but that is what makes it fascinating.

doi: 10.1038/507139b

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科学界は、データ公開、共有の倫理を慎重に議論し、データ作成者の明記など、標準的指針を作る必要がある。

Share alike p.140

Research communities need to agree on standard etiquette for data-sharing.

doi: 10.1038/507140a

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News

米オバマ政権の2015年度科学予算が、科学界の期待を裏切り、「横ばい」に。

Obama’s budget request falls flat p.147

Hopes dim for a science-funding increase in 2015.

doi: 10.1038/507147a

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中国が、研究開発の構造改革を目指し、基礎研究予算を大幅に増加へ。

China goes back to basics on research funding p.148

Core science gets budget boost in a bid to change research culture and increase innovation.

doi: 10.1038/507148a

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WHOが砂糖摂取量の抑制を呼びかける指針案をまとめたが、食品業界からの反発の予想も。

Storm brewing over WHO sugar proposal p.150

Industry backlash expected over suggested cut in intake.

doi: 10.1038/507150a

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グローバル地震観測網(GSN)が、海洋にも観測範囲を拡大へ。

Global seismic network takes to the seas p.151

Two systems could plug the ocean-sized gap in earthquake detection.

doi: 10.1038/507151a

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米バイオ燃料業界がセルロース系エタノールで巻き返しを図り、政府の支援に期待を。

Cellulosic ethanol fights for life p.152

Pioneering biofuel producers hope that US government largesse will ease their way into a tough market.

doi: 10.1038/507152a

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News Features

エネルギー:光の「島」

Energy: Islands of light p.154

マイクログリッドが、電気のない生活を送っていたへき地に電気をもたらし始めている。

doi: 10.1038/507154a

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生態学:オオカミ神話

Rethinking predators: Legend of the wolf p.158

捕食者の生態系への影響は絶大だと考えられているが、自然は必ずしもその原則に従うとはかぎらない。

doi: 10.1038/507158a

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News & Views

進化生物学:セックスと嘘とチョウ

Evolutionary biology: Sex, lies and butterflies p.172

ある種のチョウの雌が複数の有毒種の色彩パターンを模倣して捕食を免れる仕組みが、進化上保存されてきた性的分化遺伝子であるdoublesexに生じた変異によって説明されることが分かった。

doi: 10.1038/nature13066

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宇宙物理学:宇宙の重力レンズによって明らかにされた、自転するブラックホール

Astrophysics: Cosmic lens reveals spinning black hole p.173

遠方にあって質量が降着しつつある巨大ブラックホールから放出される光が、宇宙の重力レンズによって増幅され、さらに4つの成分に分割されたことで、ブラックホールの自転についての測定が可能になった。

doi: 10.1038/nature13209

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地質学:地球深部に蓄えられている水

Geology: Earth's deep water reservoir p.174

高圧実験が行われた結果、地球上の全ての大洋を足し合わせたのに匹敵する大きさの水の貯蔵庫が地球マントル深部に存在することが予測された。この予測が、ダイヤモンドに包含された鉱物の微小な試料によって、今回確認された。

doi: 10.1038/507174a

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神経変性疾患:グアニン四重鎖はリスクを4倍にする

Neurodegenerative diseases: G-quadruplex poses quadruple threat p.175

DNA反復配列の数の増大は神経変性疾患の原因になることが多い。C9orf72遺伝子中のそうした反復伸長の1つでは4本鎖からなる構造が形成されることが明らかになり、これが遺伝子の機能を4通りに変化させることが分かった。

doi: 10.1038/nature13067

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神経科学:ショウジョウバエのラブソングに見られる秩序あるランダムさ

Neuroscience: Ordered randomness in fly love songs p.177

雄のショウジョウバエが発する求愛歌の複雑さと変化の大半が、感覚的経験を運動出力に結び付ける単純な規則によって説明できることが、念入りで系統立った分析によって明らかになった。

doi: 10.1038/nature13208

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進化生物学:起こらなかった種分化

Evolutionary biology: Speciation undone p.178

雑種形成は2つの種を融合させて単一の集団にすることがある。新しい観察結果から、ガラパゴス島ではダーウィンフィンチの2つの種が現在交雑中であり、第三番目の種は同系交配によりすでに消滅したことが示唆された。

doi: 10.1038/507178b

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Review

医用工学:生物医学研究にマイクロ流体技術が果たす現在および将来の役割

The present and future role of microfluidics in biomedical research p.181

Microfluidics, a technology characterized by the engineered manipulation of fluids at the submillimetre scale, has shown considerable promise for improving diagnostics and biology research. Certain properties of microfluidic technologies, such as rapid sample processing and the precise control of fluids in an assay, have made them attractive candidates to replace traditional experimental approaches. Here we analyse the progress made by lab-on-a-chip microtechnologies in recent years, and discuss the clinical and research areas in which they have made the greatest impact. We also suggest directions that biologists, engineers and clinicians can take to help this technology live up to its potential.

doi: 10.1038/nature13118

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Articles

細胞:肺の発生、再生およびがんにおける肺胞の前駆細胞と幹細胞

Alveolar progenitor and stem cells in lung development, renewal and cancer p.190

Lung alveoli are lined by two types of alveolar epithelial cells, squamous alveolar type (AT) 1 cells that mediate gas exchange and cuboidal AT2 cells that secrete surfactant to prevent alveolar collapse during breathing; here alveolar markers, genetic lineage tracing and clonal analysis are used in mice to identify alveolar progenitor and stem cells in vivo, and to map their locations and potential during lung development, maintenance and cancer.

doi: 10.1038/nature12930

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医学:C9orf72ヌクレオチド反復構造は疾患の分子カスケードを開始させる

C9orf72 nucleotide repeat structures initiate molecular cascades of disease p.195

Structurally polymorphic C9orf72 hexanucleotide repeats cause an impairment in transcriptional processivity and lead to accumulation of truncated repeat-containing transcripts that bind to specific ribonucleoproteins, such as nucleolin, in a conformation-dependent manner resulting in nucleolar stress and C9orf72-linked pathology in amyotrophic lateral sclerosis and frontotemporal dementia.

doi: 10.1038/nature13124

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免疫:エピトープに着目したワクチン設計の原理証明

Proof of principle for epitope-focused vaccine design p.201

Computational protein design methods are used to generate new candidates for a human respiratory syncytial virus (RSV) vaccine; artificial protein scaffolds that mimic the structure of a RSV epitope are shown to induce RSV-specific neutralizing antibodies in macaques.

doi: 10.1038/nature12966

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Letters

宇宙:赤方偏移 z = 0.658の位置にある重力レンズ効果を示すクエーサーにおける強い重力領域からの反射

Reflection from the strong gravity regime in a lensed quasar at redshift z = 0.658 p.207

The co-evolution of a supermassive black hole with its host galaxy through cosmic time is encoded in its spin. At z > 2, supermassive black holes are thought to grow mostly by merger-driven accretion leading to high spin. It is not known, however, whether below z ≈ 1 these black holes continue to grow by coherent accretion or in a chaotic manner, though clear differences are predicted in their spin evolution. An established method of measuring the spin of black holes is through the study of relativistic reflection features from the inner accretion disk. Owing to their greater distances from Earth, there has hitherto been no significant detection of relativistic reflection features in a moderate-redshift quasar. Here we report an analysis of archival X-ray data together with a deep observation of a gravitationally lensed quasar at z = 0.658. The emission originates within three or fewer gravitational radii from the black hole, implying a spin parameter (a measure of how fast the black hole is rotating) of a = at the 3σ confidence level and a > 0.66 at the 5σ level. The high spin found here is indicative of growth by coherent accretion for this black hole, and suggests that black-hole growth at 0.5 ≤ z ≤ 1 occurs principally by coherent rather than chaotic accretion episodes.

doi: 10.1038/nature13031

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化学:分子振動を用いて触媒反応の選択性を調べる

Interrogating selectivity in catalysis using molecular vibrations p.210

The delineation of molecular properties that underlie reactivity and selectivity is at the core of physical organic chemistry, and this knowledge can be used to inform the design of improved synthetic methods or identify new chemical transformations. For this reason, the mathematical representation of properties affecting reactivity and selectivity trends, that is, molecular parameters, is paramount. Correlations produced by equating these molecular parameters with experimental outcomes are often defined as free-energy relationships and can be used to evaluate the origin of selectivity and to generate new, experimentally testable hypotheses. The premise behind successful correlations of this type is that a systematically perturbed molecular property affects a transition-state interaction between the catalyst, substrate and any reaction components involved in the determination of selectivity. Classic physical organic molecular descriptors, such as Hammett, Taft or Charton parameters, seek to independently probe isolated electronic or steric effects. However, these parameters cannot address simultaneous, non-additive variations to more than one molecular property, which limits their utility. Here we report a parameter system based on the vibrational response of a molecule to infrared radiation that can be used to mathematically model and predict selectivity trends for reactions with interlinked steric and electronic effects at positions of interest. The disclosed parameter system is mechanistically derived and should find broad use in the study of chemical and biological systems.

doi: 10.1038/nature13019

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化学:アミンの配座誘起遠隔メタ位C–H活性化

Conformation-induced remote meta-C–H activation of amines p.215

Achieving site selectivity in carbon–hydrogen (C–H) functionalization reactions is a long-standing challenge in organic chemistry. The small differences in intrinsic reactivity of C–H bonds in any given organic molecule can lead to the activation of undesired C–H bonds by a non-selective catalyst. One solution to this problem is to distinguish C–H bonds on the basis of their location in the molecule relative to a specific functional group. In this context, the activation of C–H bonds five or six bonds away from a functional group by cyclometallation has been extensively studied. However, the directed activation of C–H bonds that are distal to (more than six bonds away) functional groups has remained challenging, especially when the target C–H bond is geometrically inaccessible to directed metallation owing to the ring strain encountered in cyclometallation. Here we report a recyclable template that directs the olefination and acetoxylation of distal meta-C–H bonds—as far as 11 bonds away—of anilines and benzylic amines. This template is able to direct the meta-selective C–H functionalization of bicyclic heterocycles via a highly strained, tricyclic-cyclophane-like palladated intermediate. X-ray and nuclear magnetic resonance studies reveal that the conformational biases induced by a single fluorine substitution in the template can be enhanced by using a ligand to switch from ortho- to meta-selectivity.

doi: 10.1038/nature12963

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地球:ダイヤモンドの中に含まれたリングウッダイトが示す水を含むマントル遷移層

Hydrous mantle transition zone indicated by ringwoodite included within diamond p.221

The ultimate origin of water in the Earth’s hydrosphere is in the deep Earth—the mantle. Theory and experiments have shown that although the water storage capacity of olivine-dominated shallow mantle is limited, the Earth’s transition zone, at depths between 410 and 660 kilometres, could be a major repository for water, owing to the ability of the higher-pressure polymorphs of olivine—wadsleyite and ringwoodite—to host enough water to comprise up to around 2.5 per cent of their weight. A hydrous transition zone may have a key role in terrestrial magmatism and plate tectonics, yet despite experimental demonstration of the water-bearing capacity of these phases, geophysical probes such as electrical conductivity have provided conflicting results, and the issue of whether the transition zone contains abundant water remains highly controversial. Here we report X-ray diffraction, Raman and infrared spectroscopic data that provide, to our knowledge, the first evidence for the terrestrial occurrence of any higher-pressure polymorph of olivine: we find ringwoodite included in a diamond from Juína, Brazil. The water-rich nature of this inclusion, indicated by infrared absorption, along with the preservation of the ringwoodite, is direct evidence that, at least locally, the transition zone is hydrous, to about 1 weight per cent. The finding also indicates that some kimberlites must have their primary sources in this deep mantle region.

doi: 10.1038/nature13080

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遺伝学:7000年前の中石器時代のヨーロッパ人に存在した、免疫および先祖型の色素形成に関わる対立遺伝子

Derived immune and ancestral pigmentation alleles in a 7,000-year-old Mesolithic European p.225

Ancient genomic sequences have started to reveal the origin and the demographic impact of farmers from the Neolithic period spreading into Europe. The adoption of farming, stock breeding and sedentary societies during the Neolithic may have resulted in adaptive changes in genes associated with immunity and diet. However, the limited data available from earlier hunter-gatherers preclude an understanding of the selective processes associated with this crucial transition to agriculture in recent human evolution. Here we sequence an approximately 7,000-year-old Mesolithic skeleton discovered at the La Braña-Arintero site in León, Spain, to retrieve a complete pre-agricultural European human genome. Analysis of this genome in the context of other ancient samples suggests the existence of a common ancient genomic signature across western and central Eurasia from the Upper Paleolithic to the Mesolithic. The La Braña individual carries ancestral alleles in several skin pigmentation genes, suggesting that the light skin of modern Europeans was not yet ubiquitous in Mesolithic times. Moreover, we provide evidence that a significant number of derived, putatively adaptive variants associated with pathogen resistance in modern Europeans were already present in this hunter-gatherer.

doi: 10.1038/nature12960

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遺伝学:doublesexは擬態の超遺伝子である

doublesex is a mimicry supergene p.229

One of the most striking examples of sexual dimorphism is sex-limited mimicry in butterflies, a phenomenon in which one sex—usually the female—mimics a toxic model species, whereas the other sex displays a different wing pattern. Sex-limited mimicry is phylogenetically widespread in the swallowtail butterfly genus Papilio, in which it is often associated with female mimetic polymorphism. In multiple polymorphic species, the entire wing pattern phenotype is controlled by a single Mendelian ‘supergene’. Although theoretical work has explored the evolutionary dynamics of supergene mimicry, there are almost no empirical data that address the critical issue of what a mimicry supergene actually is at a functional level. Using an integrative approach combining genetic and association mapping, transcriptome and genome sequencing, and gene expression analyses, we show that a single gene, doublesex, controls supergene mimicry in Papilio polytes. This is in contrast to the long-held view that supergenes are likely to be controlled by a tightly linked cluster of loci. Analysis of gene expression and DNA sequence variation indicates that isoform expression differences contribute to the functional differences between dsx mimicry alleles, and protein sequence evolution may also have a role. Our results combine elements from different hypotheses for the identity of supergenes, showing that a single gene can switch the entire wing pattern among mimicry phenotypes but may require multiple, tightly linked mutations to do so.

doi: 10.1038/nature13112

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神経科学:ショウジョウバエでは動的な感覚の手がかりが求愛歌の構造を変化させる

Dynamic sensory cues shape song structure in Drosophila p.233

The generation of acoustic communication signals is widespread across the animal kingdom, and males of many species, including Drosophilidae, produce patterned courtship songs to increase their chance of success with a female. For some animals, song structure can vary considerably from one rendition to the next; neural noise within pattern generating circuits is widely assumed to be the primary source of such variability, and statistical models that incorporate neural noise are successful at reproducing the full variation present in natural songs. In direct contrast, here we demonstrate that much of the pattern variability in Drosophila courtship song can be explained by taking into account the dynamic sensory experience of the male. In particular, using a quantitative behavioural assay combined with computational modelling, we find that males use fast modulations in visual and self-motion signals to pattern their songs, a relationship that we show is evolutionarily conserved. Using neural circuit manipulations, we also identify the pathways involved in song patterning choices and show that females are sensitive to song features. Our data not only demonstrate that Drosophila song production is not a fixed action pattern, but establish Drosophila as a valuable new model for studies of rapid decision-making under both social and naturalistic conditions.

doi: 10.1038/nature13131

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神経科学:室傍核からAgRPニューロンへの興奮性回路が空腹を駆動する

An excitatory paraventricular nucleus to AgRP neuron circuit that drives hunger p.238

Hunger is a hard-wired motivational state essential for survival. Agouti-related peptide (AgRP)-expressing neurons in the arcuate nucleus (ARC) at the base of the hypothalamus are crucial to the control of hunger. They are activated by caloric deficiency and, when naturally or artificially stimulated, they potently induce intense hunger and subsequent food intake. Consistent with their obligatory role in regulating appetite, genetic ablation or chemogenetic inhibition of AgRP neurons decreases feeding. Excitatory input to AgRP neurons is important in caloric-deficiency-induced activation, and is notable for its remarkable degree of caloric-state-dependent synaptic plasticity. Despite the important role of excitatory input, its source(s) has been unknown. Here, through the use of Cre-recombinase-enabled, cell-specific neuron mapping techniques in mice, we have discovered strong excitatory drive that, unexpectedly, emanates from the hypothalamic paraventricular nucleus, specifically from subsets of neurons expressing thyrotropin-releasing hormone (TRH) and pituitary adenylate cyclase-activating polypeptide (PACAP, also known as ADCYAP1). Chemogenetic stimulation of these afferent neurons in sated mice markedly activates AgRP neurons and induces intense feeding. Conversely, acute inhibition in mice with caloric-deficiency-induced hunger decreases feeding. Discovery of these afferent neurons capable of triggering hunger advances understanding of how this intense motivational state is regulated.

doi: 10.1038/nature12956

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免疫:樹状細胞によるL-Myc発現は最適なT細胞プライミングに必要である

L-Myc expression by dendritic cells is required for optimal T-cell priming p.243

The transcription factors c-Myc and N-Myc—encoded by Myc and Mycn, respectively—regulate cellular growth and are required for embryonic development. A third paralogue, Mycl1, is dispensable for normal embryonic development but its biological function has remained unclear. To examine the in vivo function of Mycl1 in mice, we generated an inactivating Mycl1gfp allele that also reports Mycl1 expression. We find that Mycl1 is selectively expressed in dendritic cells (DCs) of the immune system and controlled by IRF8, and that during DC development, Mycl1 expression is initiated in the common DC progenitor concurrent with reduction in c-Myc expression. Mature DCs lack expression of c-Myc and N-Myc but maintain L-Myc expression even in the presence of inflammatory signals such as granulocyte–macrophage colony-stimulating factor. All DC subsets develop in Mycl1-deficient mice, but some subsets such as migratory CD103+ conventional DCs in the lung and liver are greatly reduced at steady state. Importantly, loss of L-Myc by DCs causes a significant decrease in in vivo T-cell priming during infection by Listeria monocytogenes and vesicular stomatitis virus. The replacement of c-Myc by L-Myc in immature DCs may provide for Myc transcriptional activity in the setting of inflammation that is required for optimal T-cell priming.

doi: 10.1038/nature12967

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医学:マラリア原虫では転写スイッチが性的発達への運命拘束を引き起こす

A transcriptional switch underlies commitment to sexual development in malaria parasites p.248

The life cycles of many parasites involve transitions between disparate host species, requiring these parasites to go through multiple developmental stages adapted to each of these specialized niches. Transmission of malaria parasites (Plasmodium spp.) from humans to the mosquito vector requires differentiation from asexual stages replicating within red blood cells into non-dividing male and female gametocytes. Although gametocytes were first described in 1880, our understanding of the molecular mechanisms involved in commitment to gametocyte formation is extremely limited, and disrupting this critical developmental transition remains a long-standing goal. Here we show that expression levels of the DNA-binding protein PfAP2-G correlate strongly with levels of gametocyte formation. Using independent forward and reverse genetics approaches, we demonstrate that PfAP2-G function is essential for parasite sexual differentiation. By combining genome-wide PfAP2-G cognate motif occurrence with global transcriptional changes resulting from PfAP2-G ablation, we identify early gametocyte genes as probable targets of PfAP2-G and show that their regulation by PfAP2-G is critical for their wild-type level expression. In the asexual blood-stage parasites pfap2-g appears to be among a set of epigenetically silenced loci prone to spontaneous activation. Stochastic activation presents a simple mechanism for a low baseline of gametocyte production. Overall, these findings identify PfAP2-G as a master regulator of sexual-stage development in malaria parasites and mark the first discovery of a transcriptional switch controlling a differentiation decision in protozoan parasites.

doi: 10.1038/nature12920

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医学:プラスモジウムの有性生殖への拘束と発生を引き起こす一連のDNA結合タンパク質

A cascade of DNA-binding proteins for sexual commitment and development in Plasmodium p.253

Commitment to and completion of sexual development are essential for malaria parasites (protists of the genus Plasmodium) to be transmitted through mosquitoes. The molecular mechanism(s) responsible for commitment have been hitherto unknown. Here we show that PbAP2-G, a conserved member of the apicomplexan AP2 (ApiAP2) family of DNA-binding proteins, is essential for the commitment of asexually replicating forms to sexual development in Plasmodium berghei, a malaria parasite of rodents. PbAP2-G was identified from mutations in its encoding gene, PBANKA_143750, which account for the loss of sexual development frequently observed in parasites transmitted artificially by blood passage. Systematic gene deletion of conserved ApiAP2 genes in Plasmodium confirmed the role of PbAP2-G and revealed a second ApiAP2 member (PBANKA_103430, here termed PbAP2-G2) that significantly modulates but does not abolish gametocytogenesis, indicating that a cascade of ApiAP2 proteins are involved in commitment to the production and maturation of gametocytes. The data suggest a mechanism of commitment to gametocytogenesis in Plasmodium consistent with a positive feedback loop involving PbAP2-G that could be exploited to prevent the transmission of this pernicious parasite.

doi: 10.1038/nature12970

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微生物学:原核細胞ArgonauteによるDNA誘導型DNA干渉

DNA-guided DNA interference by a prokaryotic Argonaute p.258

RNA interference is widely distributed in eukaryotes and has a variety of functions, including antiviral defence and gene regulation. All RNA interference pathways use small single-stranded RNA (ssRNA) molecules that guide proteins of the Argonaute (Ago) family to complementary ssRNA targets: RNA-guided RNA interference. The role of prokaryotic Ago variants has remained elusive, although bioinformatics analysis has suggested their involvement in host defence. Here we demonstrate that Ago of the bacterium Thermus thermophilus (TtAgo) acts as a barrier for the uptake and propagation of foreign DNA. In vivo, TtAgo is loaded with 5′-phosphorylated DNA guides, 13–25 nucleotides in length, that are mostly plasmid derived and have a strong bias for a 5′-end deoxycytidine. These small interfering DNAs guide TtAgo to cleave complementary DNA strands. Hence, despite structural homology to its eukaryotic counterparts, TtAgo functions in host defence by DNA-guided DNA interference.

doi: 10.1038/nature12971

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