Volume 508 Number 7496

Editorials

Cancer crossroads p.287

Efforts to understand cancer genomes should take on a fresh focus.

doi: 10.1038/508287b

Practical nonsense p.288

Downgrading practical science will impede UK students in the global workplace

doi: 10.1038/508288a

News

IPCC report under fire p.298

Critics attack panel’s lack of specific guidance on how countries should lower emissions.

doi: 10.1038/508298a

News Features

Blue energy p.302

After years in the doldrums, the quest to harvest energy from the oceans is gathering speed.

doi: 10.1038/508302a

The plastics puzzle p.306

When toxicologists warned that the plastics ingredient BPA might be harmful, consumers clamoured for something new. But problems persist.

doi: 10.1038/508306a

News & Views

Dating chimpanzees p.322

Genetic research has tracked lineages of male chimpanzees thousands of years into the past, opening the door to the study of long-term behavioural evolution in our close primate relatives.

doi: 10.1038/508322a

Up and down in Down's syndrome p.323

A comparison of identical human twins, only one of whom has Down's syndrome, reveals a genome-wide flattening of gene-expression levels in the affected individual. See Article p.345

doi: 10.1038/508323a

Catalysis marches on p.324

A fresh take on an established chemical reaction has solved a long-standing problem in organic synthesis: how to prepare single mirror-image isomers of groups known as isolated quaternary stereocentres. See Article p.340

doi: 10.1038/nature13225

Biocircuits in synchrony p.326

Cellular biocircuit design has taken a major step forward. The circuit reuses the cell's own protein-degradation system to synchronize the expression of two synthetic modules throughout an entire bacterial population. See Letter p.387

doi: 10.1038/nature13224

The ugly duckling p.327

Single crystals of tin selenide have been shown to display, along one crystallographic direction of their high-temperature state, the highest thermoelectric efficiency of any bulk material. See Letter p.373

doi: 10.1038/508327a

The stressful influence of microbes p.328

An investigation into cellular stress responses reveals how cell compartments called mitochondria use information about the surrounding metabolites and microorganisms to protect themselves from damage. See Letter p.406

doi: 10.1038/nature13220

Review

The ensemble nature of allostery p.331

Allostery is the process by which biological macromolecules transmit the effect of binding at one site to another, often distal, functional site, allowing for the regulation of activity; here facilitation of allostery through dynamic and intrinsically disordered proteins is discussed, and a framework to unify the description of allosteric mechanisms for different systems is proposed.

doi: 10.1038/nature13001

Articles

Domains of genome-wide gene expression dysregulation in Down’s syndrome p.345

By studying the transcriptome of fetal cells of monozygotic twins discordant for trisomy 21, this paper finds that differential expression between the twins is organized in domains along all chromosomes; these gene expression dysregulation domains are conserved in the mouse model of Down’s syndrome and correlate with the lamina-associated domains and replication domains.

doi: 10.1038/nature13200

Brainstem nucleus MdV mediates skilled forelimb motor tasks p.351

The authors use a combination of viral tracing and genetics to characterize the diversity of neurons projecting from mouse brainstem to motor neurons that control limb movements; in particular they discover that the medullary reticular formation ventral part (MdV) is functionally specialized for skilled forelimb motor control.

doi: 10.1038/nature13023

Skilled reaching relies on a V2a propriospinal internal copy circuit p.357

Cervical propriospinal neurons (PNs) form a genetically accessible subclass of V2a interneurons that convey both premotor output and precerebellar copy signals; their ablation in mice impairs reaching movements selectively, and activation of their internal copy projection recruits a rapid cerebellar feedback loop that modulates forelimb movement.

doi: 10.1038/nature13021

Letters

Isotopic links between atmospheric chemistry and the deep sulphur cycle on Mars p.364

Isotopic analyses of 40 Martian meteorites indicate that assimilation of sulphur into Martian magmas was a common occurrence throughout much of the planet’s history and that the atmospheric imprint of photochemical processing preserved in Martian meteoritic sulphide and sulphate is distinct from that observed in terrestrial analogues.

doi: 10.1038/nature13175

Mid-latitude interhemispheric hydrologic seesaw over the past 550,000 years p.378

Tropical and subtropical speleothems show that the latitudinal migration of the Intertropical Convergence Zone tends to produce increased precipitation in one hemisphere and drying in the other; now it is shown using speleothems from the Korean peninsula that this phenomenon extended to the mid-latitudes during the past 550,000 years.

doi: 10.1038/nature13076

A committed precursor to innate lymphoid cells p.397

A committed precursor to innate lymphoid cell lineages, but not classical natural killer and lymphoid tissue inducer cells, is derived from common lymphoid precursors and distinguished by high levels of expression of the transcription factor PLZF.

doi: 10.1038/nature13047

Structural basis for translocation by AddAB helicase–nuclease and its arrest at χ sites p.416

In bacterial cells, processing of double-stranded DNA breaks for repair by homologous recombination is dependent upon the recombination hotspot sequence χ (Chi) and is catalysed by either an AddAB- or RecBCD-type helicase–nuclease (reviewed in refs 3, 4). These enzyme complexes unwind and digest the DNA duplex from the broken end until they encounter a χ sequence, whereupon they produce a 3′ single-stranded DNA tail onto which they initiate loading of the RecA protein. Consequently, regulation of the AddAB/RecBCD complex by χ is a key control point in DNA repair and other processes involving genetic recombination. Here we report crystal structures of Bacillus subtilis AddAB in complex with different χ-containing DNA substrates either with or without a non-hydrolysable ATP analogue. Comparison of these structures suggests a mechanism for DNA translocation and unwinding, suggests how the enzyme binds specifically to χ sequences, and explains how χ recognition leads to the arrest of AddAB (and RecBCD) translocation that is observed in single-molecule experiments.

doi: 10.1038/nature13037