Badger away

doi: 10.1038/490310a

Global reach

doi: 10.1038/490309b

Life after death

doi: 10.1038/490309a

Drug firm to share raw trial data

doi: 10.1038/490322a

Antarctic seas in the balance

doi: 10.1038/490324a

Politics holds back animal engineers

doi: 10.1038/490318a

Stem-cell fraud hits febrile field

doi: 10.1038/490321a

The exoplanet next door

doi: 10.1038/490323a

Badger battle erupts in England

doi: 10.1038/490317a

Nobel work boosts drug development

doi: 10.1038/490320a

Science on the move

doi: 10.1038/490326a

Science mapped out

doi: 10.1038/490325a

Planetary scienceGalvanized lunacy p.346

doi: 10.1038/490346a

Cancer therapyTumours switch to resist p.347

doi: 10.1038/nature11489

Structural biologyBundles of insights into sugar transporters p.348

doi: 10.1038/490348a

HIVDesign by trial p.350

doi: 10.1038/490350a

Molecular biologyChoose your protein partners p.351

doi: 10.1038/490351a

EcologyThe big picture of marsh loss p.352

doi: 10.1038/490352a

The aged niche disrupts muscle stem cell quiescence p.355

The niche is a conserved regulator of stem cell quiescence and function. During ageing, stem cell function declines. To what extent and by what means age-related changes within the niche contribute to this phenomenon are unknown. Here we demonstrate that the aged muscle stem cell niche, the muscle fibre, expresses Fgf2 under homeostatic conditions, driving a subset of satellite cells to break quiescence and lose their self-renewing capacity. We show in mice that relatively dormant aged satellite cells robustly express sprouty 1 (Spry1), an inhibitor of fibroblast growth factor (FGF) signalling. Increasing FGF signalling in aged satellite cells under homeostatic conditions by removing Spry1 results in the loss of quiescence, satellite cell depletion and diminished regenerative capacity. Conversely, reducing niche-derived FGF activity through inhibition of Fgfr1 signalling or overexpression of Spry1 in satellite cells prevents their depletion. These experiments identify an age-dependent change in the stem cell niche that directly influences stem cell quiescence and function.

doi: 10.1038/nature11438

Crystal structure of a bacterial homologue of glucose transporters GLUT1–4 p.361

Glucose transporters are essential for metabolism of glucose in cells of diverse organisms from microbes to humans, exemplified by the disease-related human proteins GLUT1, 2, 3 and 4. Despite rigorous efforts, the structural information for GLUT1–4 or their homologues remains largely unknown. Here we report three related crystal structures of XylE, an Escherichia coli homologue of GLUT1–4, in complex with d-xylose, d-glucose and 6-bromo-6-deoxy-d-glucose, at resolutions of 2.8, 2.9 and 2.6 Å, respectively. The structure consists of a typical major facilitator superfamily fold of 12 transmembrane segments and a unique intracellular four-helix domain. XylE was captured in an outward-facing, partly occluded conformation. Most of the important amino acids responsible for recognition of d-xylose or d-glucose are invariant in GLUT1–4, suggesting functional and mechanistic conservations. Structure-based modelling of GLUT1–4 allows mapping and interpretation of disease-related mutations. The structural and biochemical information reported here constitutes an important framework for mechanistic understanding of glucose transporters and sugar porters in general.

doi: 10.1038/nature11524

Structure of AMP-PNP-bound vitamin B₁₂ transporter BtuCD–F p.367

The ATP-binding cassette (ABC) transporter BtuCD mediates the uptake of vitamin B₁₂ across the inner membrane of Escherichia coli. Previous structures have shown the conformations of apo states, but the transport mechanism has remained unclear. Here we report the 3.5 Å crystal structure of the transporter-binding protein complex BtuCD–BtuF (BtuCD–F) trapped in an β-γ-imidoadenosine 5′-phosphate (AMP-PNP)-bound intermediate state. Although the ABC domains (BtuD subunits) form the expected closed sandwich dimer, the membrane-spanning BtuC subunits adopt a new conformation, with the central translocation pathway sealed by a previously unrecognized cytoplasmic gate. A fully enclosed cavity is thus formed approximately halfway across the membrane. It is large enough to accommodate a vitamin B₁₂ molecule, and radioligand trapping showed that liposome-reconstituted BtuCD–F indeed contains bound B₁₂ in the presence of AMP-PNP. In combination with engineered disulphide crosslinking and functional assays, our data suggest an unexpected peristaltic transport mechanism that is distinct from those observed in other ABC transporters.

doi: 10.1038/nature11442

Hard-X-ray emission lines from the decay of 44Ti in the remnant of supernova 1987A p.373

doi: 10.1038/nature11473

Zinc isotopic evidence for the origin of the Moon p.376

doi: 10.1038/nature11507

Circuit quantum electrodynamics with a spin qubit p.380

doi: 10.1038/nature11559

Bonding and structure of a reconstructed (001) surface of SrTiO₃ from TEM p.384

doi: 10.1038/nature11563

Coastal eutrophication as a driver of salt marsh loss p.388

doi: 10.1038/nature11533

Delayed build-up of Arctic ice sheets during 400,000-year minima in insolation variability p.393

doi: 10.1038/nature11493

Nonlinear dendritic processing determines angular tuning of barrel cortex neurons in vivo p.397

doi: 10.1038/nature11451

Severe stress switches CRF action in the nucleus accumbens from appetitive to aversive p.402

doi: 10.1038/nature11436

Androgenetic haploid embryonic stem cells produce live transgenic mice p.407

doi: 10.1038/nature11435

Melanomas resist T-cell therapy through inflammation-induced reversible dedifferentiation p.412

doi: 10.1038/nature11538

Increased HIV-1 vaccine efficacy against viruses with genetic signatures in Env V2 p.417

doi: 10.1038/nature11519

A FOXO3–IRF7 gene regulatory circuit limits inflammatory sequelae of antiviral responses p.421

doi: 10.1038/nature11428

Targeting VEGF-B as a novel treatment for insulin resistance and type 2 diabetes p.426

doi: 10.1038/nature11464

Initiation of transcription-coupled repair characterized at single-molecule resolution p.431

doi: 10.1038/nature11430