大型電波望遠鏡SKA（スクエア・キロメートル・アレイ）の本部の選定過程に対する政治的干渉は、見過ごしではならない。
An array of problems p.129
Political interference in the selection process for the headquarters of the Square Kilometre Array should not go unchallenged.
doi: 10.1038/519129a
Volume 519 Number 7542
今週のハイライト
Cover Story: 人類の時代：人新世（Anthropocene）を定義する
実験進化学: 大きな細胞集団の進化動態
細胞生物学: Notumタンパク質のカルボキシルエステラーゼ活性
免疫学: 細菌による侵入ウイルス認識
宇宙物理学: 巨大銀河の星形成率
惑星科学: エンセラダスにおける熱水活動の証拠
量子物理学: 極低温における反強磁性秩序
進化学: 胚葉の年代記
ゲノミクス: 発達障害に関連する遺伝子
神経科学: 脳の世界観
医学: 自然リンパ球はエネルギー消費を増やして脂肪を減らす
目次
Editorials
人新世を新しい地質年代単位と認めるかどうかを層序学者が決定するには、もう少し時間が必要だ。
All in good time p.129
Stratigraphers have yet to decide whether the Anthropocene is a new unit of geological time.
doi: 10.1038/519129b
世界で最初の科学雑誌Philosophical Transactionsの350周年を、学術研究について深く考える機会にしたい。
In the beginning p.130
As the first true science journal marks 350 years, we must defend scholarly pursuits.
doi: 10.1038/519130a
News
ゲノム解析研究によって、中国でのH7N9鳥インフルエンザウイルスの進化の様子が明らかに。
Flu genomes trace H7N9 evolution p.137
But surveillance of avian influenza viruses is patchy and slow.
doi: 10.1038/519137a
議会の不信と干渉が、全米科学財団（NSF）に混乱を。
Mistrust and meddling unsettles US science agency p.138
National Science Foundation under pressure from lawmakers to revise its agenda.
doi: 10.1038/519138a
ヒトゲノムの変異速度は不安定で、解明には難しさが。
DNA mutation clock proves tough to set p.139
Geneticists meet to work out why the rate of change in the genome is so hard to pin down.
doi: 10.1038/519139a
20世紀の商業捕鯨で殺戮されたクジラは、およそ300万頭に上ることが明らかに。
World’s whaling slaughter tallied p.140
Commercial hunting wiped out almost three million animals last century.
doi: 10.1038/519140a
LHC 2.0 — 再稼働間近のCERNの大型ハドロン衝突型加速器の新たな可能性。
LHC 2.0: A new view of the Universe p.142
As the Large Hadron Collider switches on again, a graphical guide to what it might find.
doi: 10.1038/519142a
News Features
人新世：人類の時代
Anthropocene: The human age p.144
人類が地球に与えた影響を認め、新しい地質年代として区分しようという機運が高まっているが、その陰には激しい議論がある。
doi: 10.1038/519144a
紛争の解消：終わりなき戦い
Conflict resolution: Wars without end p.148
世界各地で血なまぐさい紛争が起こり、長期化しているが、複雑性科学を通じて紛争の解決策を見いだそうとする研究者がいる。
doi: 10.1038/19148a
News & Views
惑星科学：エンセラダスの温泉
Planetary science: Enceladus' hot springs p.162
土星の衛星であるエンセラダスに由来するケイ素に富んだ粒子が見つかったことから、エンセラダス内部では現在、岩石熱水相互作用が起こっていると考えられる。これは地球以外の場所で現在起こっている熱水活動を示す初めての証拠である。
doi: 10.1038/519162a
細胞内シグナル伝達：Wntを武装解除する
Cell signalling: Disarming Wnt p.163
分泌型酵素であるNotumが、Wntタンパク質に結合している脂質で、Wnt受容体タンパク質の活性化に必要とされるものを取り除き、それによってWntシグナル伝達経路を阻害していることが分かった。
doi: 10.1038/nature14208
進化：適応中の集団で適応度を追跡する
Evolution: Fitness tracking for adapting populations p.164
進化中の集団に含まれる数十万個に及ぶ酵母細胞の子孫を追跡するシステムが開発され、数千の細胞が集団全体の適応度の初期の上昇に関わっていることが明らかになった。
doi: 10.1038/nature14207
微生物学：細菌が侵入者からスペーサーを手に入れる仕組み
Microbiology: How bacteria get spacers from invaders p.166
細菌はCRISPR–Cas系を使ってウイルスに対する免疫を生じさせる。このような系がウイルスのDNA断片を選び出して、細菌のDNAに組み込み、侵入者に関する記憶とする仕組みが、今回詳しく解明された。
doi: 10.1038/nature14204
気候変動：黒色炭素と大気フィードバック
Climate change: Black carbon and atmospheric feedbacks p.167
気候シミュレーションによって、黒色炭素粒子のような光を吸収する粒子の気候に対する影響をくまなく評価する際には、こうした粒子と大気中での対流過程および雲過程の間の相互作用を考慮する必要があることが示唆された。
doi: 10.1038/519167a
進化生物学：陸生動物での聴覚の起源
Evolutionary biology: The origin of terrestrial hearing p.168
アフリカハイギョの研究から、この生物には音によって生じる圧力波を検知する未発達の能力があることが明らかになった。この知見は、四肢と指を持つ最初の脊椎動物である初期四肢類で聴力がどのようにして生じたのかについて解明を進めるものだ。
doi: 10.1038/519168a
Perspective
生物地理学：人新世の定義
Defining the Anthropocene p.171
Formal criteria must be met to define a new human-driven epoch; the geological evidence appears to do so, with 1610 and 1964 both likely to satisfy the requirements for the start of the Anthropocene.
doi: 10.1038/nature14258
Articles
実験進化学：高分解能の系統追跡法を用いた進化動態の定量
Quantitative evolutionary dynamics using high-resolution lineage tracking p.181
Random DNA barcodes were used to simultaneously track hundreds of thousands of lineages in large cell populations, revealing deterministic dynamics early in their evolution.
doi: 10.1038/nature14279
細胞生物学：NotumはWntタンパク質を脱アシル化してシグナル伝達活性を抑制する
Notum deacylates Wnt proteins to suppress signalling activity p.187
The biochemical activity of Notum as a carboxylesterase that removes an essential lipid moiety from Wnt proteins is uncovered; the interaction of Notum with glypicans is required to ensure localization at the cell surface, and Notum may provide a new target for therapeutic development in diseases with defective Wnt signalling.
doi: 10.1038/nature14259
免疫学：CRISPR–Cas獲得免疫の際のインテグラーゼを介したスペーサー獲得
Integrase-mediated spacer acquisition during CRISPR–Cas adaptive immunity p.193
The bacterial CRISPR/Cas system acquires short phage sequences known as spacers that integrate between CRISPR repeats and constitute a record of phage infection; this study shows that the Cas1–Cas2 complex is the minimal machinery required for spacer acquisition and the complex integrates oligonucleotide DNA substrates into acceptor DNA in a manner similar to retroviral integrases and DNA transposases with Cas 1 as the catalytic subunit and Cas2 acting to increase integration activity.
doi: 10.1038/nature14237
免疫学：Cas9はCRISPR–Casによる獲得免疫過程で機能を備えたウイルス標的を特定する
Cas9 specifies functional viral targets during CRISPR–Cas adaptation p.199
Bacterial CRISPR–Cas loci acquire short phage sequences called spacers that integrate between DNA repeats and how these viral sequences are chosen was unknown; in these studies of the type II CRISPR–Cas system of Streptococcus pyogenes, the Cas9 nuclease known to inactivate invading viral DNA was found to be required for the selection of functional spacers during CRISPR immunity.
doi: 10.1038/nature14245
Letters
宇宙物理学：降下、フィードバックおよび熱伝導による巨大銀河の星形成の調整
Regulation of star formation in giant galaxies by precipitation, feedback and conduction p.203
Observations confirm models of galaxy cooling in which cold clouds precipitate out of hot gas via thermal instability, and the precipitation threshold is incorporated into a theoretical framework that explains how precipitation and thermal conduction regulate star formation.
doi: 10.1038/nature14167
惑星科学：エンセラダス内の今も続いている熱水活動
Ongoing hydrothermal activities within Enceladus p.207
Analysis of silicon-rich, nanometre-sized dust particles near Saturn shows them to consist of silica, which was initially embedded in icy grains emitted from Enceladus’ subsurface waters and released by sputter erosion in Saturn’s E ring; their properties indicate their ongoing formation and transport by high-temperature hydrothermal reactions from the ocean floor and up into the plume of Enceladus.
doi: 10.1038/nature14262
量子物理学：極低温原子を用いたハバード模型における反強磁性相関の観測
Observation of antiferromagnetic correlations in the Hubbard model with ultracold atoms p.211
Ultracold atomic gases in optical lattices potentially offer simulations of condensed-matter phenomena beyond what theory and computations can access; compensated optical lattice techniques applied to the Hubbard model now enable unprecedented low temperatures to be reached for fermions — only 1.4 times that of the antiferromagnetic phase transition, approaching the limits of present modelling techniques.
doi: 10.1038/nature14223
気候科学：大気の温暖化の増大に伴う北半球の硬水湖からの二酸化炭素流出量の減少
Decrease in CO2 efflux from northern hardwater lakes with increasing atmospheric warming p.215
Atmospheric warming may reduce CO2 emissions from hardwater lakes by reducing the duration of ice cover, increasing lake water pH and favouring CO2 sequestration.
doi: 10.1038/nature14172
進化学：時空間的トランスクリプトミクスで明らかになった内胚葉の進化史
Spatiotemporal transcriptomics reveals the evolutionary history of the endoderm germ layer p.219
Studies of gene-expression levels in embryos of Caenorhabditis elegant and of other phyla reveal the timing and location of expression of all genes and support a model in which the endoderm program dates back to the origin of multicellularity while the ectoderm originated as a secondary germ layer freed from ancestral feeding functions.
doi: 10.1038/nature13996
ゲノミクス：発達障害の新たな遺伝的原因を大規模な探索により発見
Large-scale discovery of novel genetic causes of developmental disorders p.223
Up to half of children with severe developmental disorders of probable genetic origin remain without a genetic diagnosis; here, in a systematic and nationwide study of 1,133 children with severe, undiagnosed developmental disorders, and their parents, exome sequencing and array-based detection of chromosomal rearrangements reveals novel genes causing developmental disorders, increasing the proportion of children that can now be diagnosed to 31%.
doi: 10.1038/nature14135
神経科学：マウス上丘の方位選択性カラム
Orientation columns in the mouse superior colliculus p.229
Population recordings reveal that neurons in the mouse superior colliculus are grouped according to their preferred orientations or movement axes for visual line stimuli, similar to the columnar arrangement in visual cortex of higher mammals; this functional architecture suggests that the superior colliculus samples the visual world unevenly for stimulus orientations.
doi: 10.1038/nature14103
神経科学：機械感覚的相互作用が、ショウジョウバエの集団行動を促す
Mechanosensory interactions drive collective behaviour in Drosophila p.233
Collective behaviour in animal groups can improve individual perception and decision-making, but the neural mechanisms involved have been hard to access in classic models for these phenomena; here it is shown that Drosophila’s olfactory responses are enhanced in groups of flies, through mechanosensory neuron-dependent touch interactions.
doi: 10.1038/nature14024
免疫学：アレルギー様薬剤反応に重要なマスト細胞特異的受容体の同定
Identification of a mast-cell-specific receptor crucial for pseudo-allergic drug reactions p.237
Cationic substances, including some drugs, can activate mast cells in an IgE-independent manner, leading to histamine release, inflammation and airway contraction; here, the G-protein-coupled receptor MrgprB2, the orthologue of human MRGPRX2, is shown to be the sole mast cell receptor for these substances in mice.
doi: 10.1038/nature14022
医学：グループ2自然リンパ球は白色脂肪組織のベージュ化を促して肥満を制限する
Group 2 innate lymphoid cells promote beiging of white adipose tissue and limit obesity p.242
Group 2 innate lymphoid cells are shown to have a critical role in energy homeostasis by producing methionine-enkephalin peptides in response to interleukin 33, thus promoting the beiging of white adipose tissue; increased numbers of beige (also known as brown-like or brite) fat cells in white adipose tissue leads to increased energy expenditure and decreased adiposity.
doi: 10.1038/nature14115
構造生物学：不眠症治療薬スボレキサントと結合したヒトOX2オレキシン受容体の結晶構造
Crystal structure of the human OX2 orexin receptor bound to the insomnia drug suvorexant p.247
The orexin system regulates sleep and arousal in humans, with orexin receptor antagonists becoming promising therapeutics for insomnia; now, the X-ray crystal structure of the human OX2 receptor in the presence of the insomnia drug suvorexant is solved.
doi: 10.1038/nature14035
