Table of Contents

Volume 525 Number 7568 pp157-284

10 September 2015

About the cover

A three-dimensional representation of a ‘world of trees’ based on a new map of global tree density. Features and countries you can see have trees, the others (like the Sahara) have virtually none. Until now, our understanding of global forest ecosystems has been generated from satellite information that can tell us about the area of forest. Policy makers and environmental scientists have relied heavily on this information when considering trees’ involvement in patterns of biodiversity, biogeochemical cycles and their contribution to ecosystem services. Thomas Crowther et al. have extended the scope of this information by generating a map of global tree density that reveals what is going on below the canopy. The map, which was generated using more than 400,000 ground-sourced measurements of tree density, reveals patterns in tree numbers at regional and global scales. Using this map, the authors are able to estimate that the current global tree number stands at approximately 3 trillion. Cover art: Jan Willem Tulp using Processing (

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  • Mapping tree density at a global scale

    • T. W. Crowther
    • H. B. Glick
    • K. R. Covey
    • C. Bettigole
    • D. S. Maynard
    • S. M. Thomas
    • J. R. Smith
    • G. Hintler
    • M. C. Duguid
    • G. Amatulli
    • M.-N. Tuanmu
    • W. Jetz
    • C. Salas
    • C. Stam
    • D. Piotto
    • R. Tavani
    • S. Green
    • G. Bruce
    • S. J. Williams
    • S. K. Wiser
    • M. O. Huber
    • G. M. Hengeveld
    • G.-J. Nabuurs
    • E. Tikhonova
    • P. Borchardt
    • C.-F. Li
    • L. W. Powrie
    • M. Fischer
    • A. Hemp
    • J. Homeier
    • P. Cho
    • A. C. Vibrans
    • P. M. Umunay
    • S. L. Piao
    • C. W. Rowe
    • M. S. Ashton
    • P. R. Crane
    • M. A. Bradford

    Ground-sourced tree density data is assembled to provide a global map of tree density, which reveals that there are three trillion trees (tenfold more than previous estimates); tree numbers have declined by nearly half since the start of human civilization and over 15 billion trees are lost on an annual basis.

    See also
  • Gain-of-function p53 mutants co-opt chromatin pathways to drive cancer growth

    • Jiajun Zhu
    • Morgan A. Sammons
    • Greg Donahue
    • Zhixun Dou
    • Masoud Vedadi
    • Matthäus Getlik
    • Dalia Barsyte-Lovejoy
    • Rima Al-awar
    • Bryson W. Katona
    • Ali Shilatifard
    • Jing Huang
    • Xianxin Hua
    • Cheryl H. Arrowsmith
    • Shelley L. Berger

    A ChIP-seq analysis of the DNA-binding properties of mutant gain-of-function p53 protein compared to wild-type p53 reveals the gain-of-function proteins bind to and activate a distinct set of genes including chromatin modifying enzymes such as the histone methyltransferase MLL; small molecular inhibitors of MLL function may represent a new target for cancers with mutant p53.

    See also
  • An atomic structure of human γ-secretase

    • Xiao-chen Bai
    • Chuangye Yan
    • Guanghui Yang
    • Peilong Lu
    • Dan Ma
    • Linfeng Sun
    • Rui Zhou
    • Sjors H. W. Scheres
    • Yigong Shi

    The atomic structure of human γ-secretase at 3.4 Å resolution, determined by single-particle cryo-electron microscopy.


  • Quadrature squeezed photons from a two-level system

    • Carsten H. H. Schulte
    • Jack Hansom
    • Alex E. Jones
    • Clemens Matthiesen
    • Claire Le Gall
    • Mete Atatüre

    Measurements of a steady emission of single photons from a quantum dot demonstrate that the fluctuations of the electric field can periodically be 3% below the fundamental quantum limit and confirm the long-standing prediction that the quantum state of single photons can be squeezed.

  • The most incompressible metal osmium at static pressures above 750 gigapascals

    • L. Dubrovinsky
    • N. Dubrovinskaia
    • E. Bykova
    • M. Bykov
    • V. Prakapenka
    • C. Prescher
    • K. Glazyrin
    • H.-P. Liermann
    • M. Hanfland
    • M. Ekholm
    • Q. Feng
    • L. V. Pourovskii
    • M. I. Katsnelson
    • J. M. Wills
    • I. A. Abrikosov

    Subtle anomalies in how the structure of metallic osmium evolves with pressure are detected using powder X-ray diffraction measurements at ultra-high static pressures; the anomaly at 440 gigapascals is attributed to an electronic transition caused by pressure-induced interactions between core electrons.

  • Computational design of co-assembling protein–DNA nanowires

    • Yun Mou
    • Jiun-Yann Yu
    • Timothy M. Wannier
    • Chin-Lin Guo
    • Stephen L. Mayo

    Computational protein design is used to create a protein–DNA co-assembling nanomaterial; by varying the arrangement of protein-binding sites on the double-stranded DNA, a ‘nanowire’ with single-molecule width can be spontaneously formed by mixing the protein and double-stranded DNA building blocks.

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    • Theodore W. Wilson
    • Luis A. Ladino
    • Peter A. Alpert
    • Mark N. Breckels
    • Ian M. Brooks
    • Jo Browse
    • Susannah M. Burrows
    • Kenneth S. Carslaw
    • J. Alex Huffman
    • Christopher Judd
    • Wendy P. Kilthau
    • Ryan H. Mason
    • Gordon McFiggans
    • Lisa A. Miller
    • Juan J. Nájera
    • Elena Polishchuk
    • Stuart Rae
    • Corinne L. Schiller
    • Meng Si
    • Jesús Vergara Temprado
    • Thomas F. Whale
    • Jenny P. S. Wong
    • Oliver Wurl
    • Jacqueline D. Yakobi-Hancock
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    • Simon Mead
    • Matthew Ellis
    • Jonathan D. F. Wadsworth
    • Andrew J. Nicoll
    • Joanna Kenny
    • Francesca Launchbury
    • Jacqueline Linehan
    • Angela Richard-Loendt
    • A. Sarah Walker
    • Peter Rudge
    • John Collinge
    • Sebastian Brandner

    Treatment of children with human cadaver-derived growth hormone (c-hGH) contaminated with prions resulted in transmission of Creutzfeldt–Jakob disease (CJD); unexpectedly, in an autopsy study of eight such iCJD patients, the authors found amyloid-β deposition in the grey matter typical of that seen in Alzheimer's disease and amyloid-β in the blood vessel walls characteristic of cerebral amyloid angiopathy, consistent with iatrogenic transmission of amyloid-β pathology in addition to CJD and suggests that healthy c-hGH-exposed individuals may also be at risk of Alzheimer's disease and cerebral amyloid angiopathy.

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  • Single-cell messenger RNA sequencing reveals rare intestinal cell types

    • Dominic Grün
    • Anna Lyubimova
    • Lennart Kester
    • Kay Wiebrands
    • Onur Basak
    • Nobuo Sasaki
    • Hans Clevers
    • Alexander van Oudenaarden

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  • Distinct EMT programs control normal mammary stem cells and tumour-initiating cells

    • Xin Ye
    • Wai Leong Tam
    • Tsukasa Shibue
    • Yasemin Kaygusuz
    • Ferenc Reinhardt
    • Elinor Ng Eaton
    • Robert A. Weinberg

    This study finds that the epithelial-to-mesenchymal (EMT) transition program, which is common to both mammary gland reconstituting stem cells and mammary tumour-initiating cells, is differentially regulated by two distinct EMT factors, Slug and Snail; the findings illustrate that although they appear similar, normal tissue stem cells and tumour-initiating cells are controlled by distinct regulatory processes.

  • Allosteric receptor activation by the plant peptide hormone phytosulfokine

    • Jizong Wang
    • Hongju Li
    • Zhifu Han
    • Heqiao Zhang
    • Tong Wang
    • Guangzhong Lin
    • Junbiao Chang
    • Weicai Yang
    • Jijie Chai

    Insights derived from the crystal structures of the extracellular domain of PSKR, the receptor for the plant hormone phytosulfokine (PSK) that affects plant growth and development, reveal that PSK interacts with PSKR and enhances PSKR interaction with its co-receptor SERK allosterically.

  • Real-time observation of the initiation of RNA polymerase II transcription

    • Furqan M. Fazal
    • Cong A. Meng
    • Kenji Murakami
    • Roger D. Kornberg
    • Steven M. Block

    A single-molecule optical tweezer assay is developed to monitor transcription initiation in eukaryotic RNA polymerase II in real-time, making use of a highly purified preinitiation complex (PIC) from yeast; observations show that a large bubble is opened up in the DNA template during initiation, driven by the TFIIH helicase that forms part of the PIC, along with synthesis of an extended transcript before the transition from transcription initiation into elongation.