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 (http://processing.org/)

This Week

Editorials

Top
  • Keep a welcome

    The plight of a record number of refugees is something the West cannot ignore. Humanitarian values should be upheld, and people fleeing war and persecution must be offered protection.

  • Money matters

    It is not how much people have, it is how much we know they have that stokes inequality.

  • Loaded language

    There can be more to a question than appears at first sight.

World View

Top

Seven Days

Top

News in Focus

Features

Top

comment

Books and Arts

Top
  • Genetics: Dawkins, redux

    Nathaniel Comfort takes issue with the second instalment of the evolutionary biologist's autobiography.

    • Review of Brief Candle in the Dark: My Life in Science
      Richard Dawkins
  • Books in brief

    Barbara Kiser reviews five of the week's best science picks.

  • Q&A: The academic satirist

    Cartoonist and former robotics researcher Jorge Cham wowed graduate students with The PhD Movie in 2011. With the follow-up The PhD Movie 2: Still in Grad School — an astute, funny look at more academic tribulations — set to screen at campuses worldwide from the end of September, Cham talks about crowdfunding, the grim scrabble for grants, the under-representation of women in science and coaxing a cameo from a Nobel laureate.

    • Review of The PhD Movie 2

Obituary

Top

Careers

Features

Top

Q&As

Top
  • Trade talk: Fund manager

    A funds manager explains how his physics PhD helped him to transition into the world of finance and investments.

    • Julie Gould

naturejobs job listings and advertising features

Futures

  • Neuraugment, verb

    Standard United Galactic Treaty Dictionary, 2nd edn, Caelum Univ. Press (11 June 2287).

    • Felicia Davin

research

Articles

Top
  • 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.

Letters

Top
  • 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.

  • A marine biogenic source of atmospheric ice-nucleating particles

    • 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
    • Jonathan P. D. Abbatt
    • Josephine Y. Aller
    • Allan K. Bertram
    • Daniel A. Knopf
    • Benjamin J. Murray

    The presence of ice in clouds can influence cloud lifetime, precipitation and radiative properties; here, organic material at the sea–air interface, possibly associated with phytoplankton cell exudates, is shown to nucleate ice under conditions relevant for ice cloud formation in the atmospheric environment.

    See also
  • Evolutionary origin of the turtle skull

    • G. S. Bever
    • Tyler R. Lyson
    • Daniel J. Field
    • Bhart-Anjan S. Bhullar

    Computed tomography and phylogenetic analysis of the Eunotosaurus africanus skull suggests that not only is Eunotosaurus an early relative of the group that eventually evolved into turtles, but that it is also a diapsid caught in the act of evolving towards a secondarily anapsid state.

  • Evidence for human transmission of amyloid-β pathology and cerebral amyloid angiopathy

    • Zane Jaunmuktane
    • 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.

    See also
  • 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

    An algorithm that allows rare cell type identification in a complex population of single cells, based on single-cell mRNA-sequencing, is applied to mouse intestinal cells, revealing novel subtypes of enteroendocrine cells and showing that the Lgr5-expressing population consists of a homogenous stem cell population with a few rare secretory cells, including Paneth cells.

    See also
  • 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.

Corrigendum

Top