Volume 494 Number 7435

Editorials

Unknown territory p.5

Japan is making an overdue effort to regulate experimental stem-cell treatments. A clearly defined legal framework is needed to protect patients.

doi: 10.1038/494005a

In a hole p.5

It is in Britain’s best interests to keep looking for a site for a deep nuclear-waste repository.

doi: 10.1038/494005b

Body of evidence p.6

The identification of a long-dead king is not simply an academic event.

doi: 10.1038/494006a

News

LHC set to halt for upgrades p.16

Maintenance, improvement work and data analysis will keep scientists busy as collider’s planned closure begins.

doi: 10.1038/494016a

News Features

Translational research: Medicine man p.24

As director of the NIH's bold new translational research centre, Christopher Austin has to show that he can jump-start a tortuous drug-discovery process.

doi: 10.1038/494024a

News & Views

Microbiology: The life beneath our feet p.40

Our planet's soils teem with microorganisms that regulate processes from crop productivity to carbon sequestration. Molecular analysis contributes hugely to the characterization of microbial communities, but how can we better understand their ecological functions? Two microbiologists discuss the advantages of data-mining approaches versus targeted experiments.

doi: 10.1038/494040a

Solid-state physics: A new spin on spintronics p.43

By harnessing the way charge carriers move in a magnetic field, computing blocks based on semiconductor junctions have been made that are reconfigurable and can be interconnected to perform complex logic functions. See Letter p.72

doi: 10.1038/nature11944

Neuroscience: Salty sensations p.44

Salt is important in health and disease, yet how mammals sense it is not completely clear. Evidence in worms suggests that TMC proteins, which are implicated in human hearing, are salt receptors involved in taste. See Letter p.95

doi: 10.1038/nature11946

Fungal biology: Multiple mating strategies p.45

Unusual strains of the pathogen Candida albicans have been found that contain a single set of chromosomes. Formation of such haploid strains weeds out damaged copies of genes to promote evolution in the human body. See Article p.55

doi: 10.1038/nature11945

Astrophysics: Going supernova p.46

When massive stars die as supernovae, these explosions can be seen out to the 'edge of the Universe'. But the stars' nature is often unclear. New observations provide insight into the life of one such star before it exploded. See Letter p.65

doi: 10.1038/494046a

Review

Spin–orbit coupling in quantum gases p.49

The current experimental and theoretical status of spin–orbit coupling in ultracold atomic systems is discussed, highlighting unique features that enable otherwise impossible physics.

doi: 10.1038/nature11841

Articles

The ‘obligate diploid’ Candida albicans forms mating-competent haploids p.55

Candida albicans, the most prevalent human fungal pathogen, is considered to be an obligate diploid that carries recessive lethal mutations throughout the genome. Here we demonstrate that C. albicans has a viable haploid state that can be derived from diploid cells under in vitro and in vivo conditions, and that seems to arise through a concerted chromosome loss mechanism. Haploids undergo morphogenetic changes like those of diploids, including the yeast–hyphal transition, chlamydospore formation and a white-opaque switch that facilitates mating. Haploid opaque cells of opposite mating type mate efficiently to regenerate the diploid form, restoring heterozygosity and fitness. Homozygous diploids arise spontaneously by auto-diploidization, and both haploids and auto-diploids show a similar reduction in fitness, in vitro and in vivo, relative to heterozygous diploids, indicating that homozygous cell types are transient in mixed populations. Finally, we constructed stable haploid strains with multiple auxotrophies that will facilitate molecular and genetic analyses of this important pathogen.

doi: 10.1038/nature11865

Structural basis for viral 5′-PPP-RNA recognition by human IFIT proteins p.60

Interferon-induced proteins with tetratricopeptide repeats (IFITs) are innate immune effector molecules that are thought to confer antiviral defence through disruption of protein–protein interactions in the host translation-initiation machinery. However, it was recently discovered that IFITs can directly recognize viral RNA bearing a 5′-triphosphate group (PPP-RNA), which is a molecular signature that distinguishes it from host RNA. Here we report crystal structures of human IFIT5, its complex with PPP-RNAs, and an amino-terminal fragment of IFIT1. The structures reveal a new helical domain that houses a positively charged cavity designed to specifically engage only single-stranded PPP-RNA, thus distinguishing it from the canonical cytosolic sensor of double-stranded viral PPP-RNA, retinoic acid-inducible gene I (RIG-I, also known as DDX58). Mutational analysis, proteolysis and gel-shift assays reveal that PPP-RNA is bound in a non-sequence-specific manner and requires a 5′-overhang of approximately three nucleotides. Abrogation of PPP-RNA binding in IFIT1 and IFIT5 was found to cause a defect in the antiviral response by human embryonic kidney cells. These results demonstrate the mechanism by which IFIT proteins selectively recognize viral RNA, and lend insight into their downstream effector function.

doi: 10.1038/nature11783

Letters

Magnetic-field-controlled reconfigurable semiconductor logic p.72

A microchannel made from InSb, which has current–voltage characteristics that are strongly dependent on the sign and magnitude of an applied magnetic field, is used to demonstrate that circuits made from such structures can be programmed — and reprogrammed — to perform elementary logic functions, such as AND, OR, NAND and NOR.

doi: 10.1038/nature11817

ATP-directed capture of bioactive herbal-based medicine on human tRNA synthetase p.121

The crystal structure of prolyl tRNA synthetase simultaneously bound to its substrate ATP and its inhibitor halofuginone, a derivative of a compound used to treat malaria, indicates that (through interactions with ATP) halofuginone occupies both the amino acid and tRNA binding sites on the synthetase, revealing a new model for developing synthetase inhibitors.

doi: 10.1038/nature11774

Mitotic cell rounding accelerates epithelial invagination p.125

Drosophila epithelial tracheal placode invagination is shown to be driven by mitotic cell rounding along with epithelial growth factor receptor signalling and myosin contractility in neighbouring cells, revealing a new cell-division-independent role for mitotic events in morphogenesis.

doi: 10.1038/nature11792