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Genetics: Dawkins, redux
Nathaniel Comfort takes issue with the second instalment of the evolutionary biologist's autobiography.
Nathaniel Comfort |
Books in brief
Barbara Kiser reviews five of the week's best science picks.
Barbara Kiser |
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.
Zoë Corbyn |
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Neuroscience: Forgetfulness illuminated
Memories are stored in the complex network of neurons in the brain. With the help of innovative tools to manipulate the connections between neurons, memories in mice can now be erased with a beam of light.
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Epigenetics: The karma of oil palms
Despite their clonal origin, some oil palm trees develop fruits that give almost no oil. It emerges that the number of methyl groups attached to a DNA region called Karma determine which plants are defective.
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Parkinson's disease: Crystals of a toxic core
An ultra-high-resolution structure of the core segment of assembled α-synuclein — the protein that aggregates in the brains of patients with Parkinson's disease — has been determined. A neurobiologist and a structural biologist discuss the implications of this advance.
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Glycine receptor mechanism elucidated by electron cryo-microscopy
A high-resolution electron cryo-microscopy structure of the zebrafish α1 glycine receptor bound to agonists or antagonists reveals the conformational changes that take place when the channel transitions from closed to open state.
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Panorama of ancient metazoan macromolecular complexes
Using biochemical fractionation and mass spectrometry, animal protein complexes are identified from nine species in parallel, and, along with genome sequence information, complex conservation is investigated and over one million protein–protein interactions are predicted in 122 eukaryotes.
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Structure of mammalian eIF3 in the context of the 43S preinitiation complex
The cryo-electron microscopy structure of the eukaryotic initiation factor 3 (eIF3) within the larger 43S complex is determined; the improved resolution enables visualization of the secondary structures of the subunits, as well as the contacts between eIF3 and both eIF2 and DHX29.
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Labelling and optical erasure of synaptic memory traces in the motor cortex
A new light-activated probe that targets recently active neuronal spines for manipulation induces shrinkage of recently potentiated spines following a motor learning task; spine shrinkage disrupted learning, suggesting a causal relationship between the specific subset of targeted spines and the learned behaviour.
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Structure of the toxic core of α-synuclein from invisible crystals
A short segment of α-synuclein called NACore (residues 68–78) is responsible for the formation of amyloid aggregates responsible for cytotoxicity in Parkinson disease; here the nanocrystal structure of this invisible-to-optical-microscopy segment is determined using micro-electron diffraction, offering insight into its function and simultaneously demonstrating the first use of micro-electron diffraction to solve a previously unknown protein structure.
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Spawning rings of exceptional points out of Dirac cones
Exceptional points are singularities in non-Hermitian systems that can produce unusual effects, and it is shown that a Dirac cone in a photonic crystal can generate a continuous ring of exceptional points through flattening the tip of the cone.
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A new cyanogenic metabolite in Arabidopsis required for inducible pathogen defence
Untargeted metabolomics and coexpression analysis uncovers the complete biosynthetic pathway of a previously unknown Arabidopsis metabolite, 4-hydroxyindole-3-carbonyl nitrile (4-OH-ICN), which harbours cyanogenic functionality.
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Crystal structures of a double-barrelled fluoride ion channel
Microorganisms can export toxic fluoride ions through highly selective channels of the Fluc family; here, the crystal structures of two bacterial Fluc homologues are presented, revealing that selectivity for small F− ions may arise from the proteins’ narrow pores and unusual anion coordination.
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Loss of Karma transposon methylation underlies the mantled somaclonal variant of oil palm
The oil palm fruit ‘mantled’ abnormality is a somaclonal variant that markedly reduces yield; here, a genome-wide DNA methylation analysis finds that hypomethylation of a single Karma family retrotransposon embedded in a homeotic gene intron is common to all mantled clones and is associated with aberrant splicing and termination of the gene transcript, and that loss of methylation predicts a loss of oil palm yield.
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Inequality and visibility of wealth in experimental social networks
Wealth inequality and wealth visibility can potentially affect overall levels of cooperation and economic success, and an online experiment was used to test how these factors interact; wealth inequality by itself did not substantially damage overall cooperation or overall wealth, but making wealth levels visible had a detrimental effect on social welfare.
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Mapping tree density at a global scale
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.
T. W. Crowther, H. B. Glick, K. R. Covey et al. |
Gain-of-function p53 mutants co-opt chromatin pathways to drive cancer growth
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.
Jiajun Zhu, Morgan A. Sammons, Greg Donahue et al. |
An atomic structure of human γ-secretase
The atomic structure of human γ-secretase at 3.4 Å resolution, determined by single-particle cryo-electron microscopy.
Xiao-chen Bai, Chuangye Yan, Guanghui Yang et al. |
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Dense cloud cores revealed by CO in the low metallicity dwarf galaxy WLM
To understand the birth of stars, observations of the clouds in which they form are key; here, interferometric observations are reported of carbon monoxide clouds in the galaxy WLM, which has a metallicity that is 13 per cent of the value of our Sun.
Monica Rubio, Bruce G. Elmegreen, Deidre A. Hunter et al. |
Quadrature squeezed photons from a two-level system
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.
Carsten H. H. Schulte, Jack Hansom, Alex E. Jones et al. |
The most incompressible metal osmium at static pressures above 750 gigapascals
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.
L. Dubrovinsky, N. Dubrovinskaia, E. Bykova et al. |
Computational design of co-assembling protein–DNA nanowires
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.
Yun Mou, Jiun-Yann Yu, Timothy M. Wannier et al. |
A marine biogenic source of atmospheric ice-nucleating particles
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.
Theodore W. Wilson, Luis A. Ladino, Peter A. Alpert et al. |
Evolutionary origin of the turtle skull
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.
G. S. Bever, Tyler R. Lyson, Daniel J. Field et al. |
Arithmetic and local circuitry underlying dopamine prediction errors
Dopamine neurons in the ventral tegmental area calculate reward prediction error by subtracting input from neighbouring GABA neurons.
Neir Eshel, Michael Bukwich, Vinod Rao et al. |
Evidence for human transmission of amyloid-β pathology and cerebral amyloid angiopathy
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.
Zane Jaunmuktane, Simon Mead, Matthew Ellis et al. |
Single-cell messenger RNA sequencing reveals rare intestinal cell types
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.
Dominic Grün, Anna Lyubimova, Lennart Kester et al. |
Distinct EMT programs control normal mammary stem cells and tumour-initiating cells
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.
Xin Ye, Wai Leong Tam, Tsukasa Shibue et al. |
A spatial model predicts that dispersal and cell turnover limit intratumour heterogeneity
A new model of tumour evolution is presented to explain how short-range migration and cell turnover within the tumour can provide the basic environment of rapid cell mixing, allowing even a small selective advantage to dominate the mass within relevant time frames.
Bartlomiej Waclaw, Ivana Bozic, Meredith E. Pittman et al. |
Allosteric receptor activation by the plant peptide hormone phytosulfokine
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.
Jizong Wang, Hongju Li, Zhifu Han et al. |
Structural basis of JAZ repression of MYC transcription factors in jasmonate signalling
Structural view of a dynamic molecular switch mechanism that governs repression and activation of the jasmonate plant hormone pathway.
Feng Zhang, Jian Yao, Jiyuan Ke et al. |
Real-time observation of the initiation of RNA polymerase II transcription
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.
Furqan M. Fazal, Cong A. Meng, Kenji Murakami et al. |
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