The United States must boost energy spending to make its mark on the climate debate.
Governments and funding agencies must do more to prevent the awarding of grants to research projects with significant overlap.
Research balloons have taught us much about the atmosphere, and could now fly into space.
Graphene and virtual brain win billion-euro competition.
Wide-ranging review edges towards single funding pot.
Researchers marshal technology in bid to thwart fungal outbreak in Central America.
Nature probe reveals lack of oversight of researchers who win two grants for similar projects.
Alternative transistor relies on exotic semiconductor.
President will use regulations to sidestep stalled Congress.
We may be seeing some of the Solar System's most striking objects during rare moments of glory.
Size limits have been a part of fisheries management for decades, but some fear that they are doing more harm than good.
News & Views
Some worker fire ants will tolerate multiple queens in their colony, but others only one. It turns out that this behaviour is governed by a gene cluster on an unusual pair of chromosomes. Two scientists describe what these findings mean to the fields of social evolution, genetics and beyond. See Letter p.664
The Sun's magnetic activity varies cyclically over a period of about 11 years. An analysis of a new, temporally extended proxy record of this activity hints at a possible planetary influence on the amplitude of the cycle.
The spliceosome complex removes intron sequences from RNA transcripts to form messenger RNA. The structure of a spliceosomal protein, Prp8, reveals the complex's active site and casts light on the origin of splicing. See Article p.638
Breakdown of dissolved organic nitrogen in the ocean had been thought to be the preserve of microbes at the surface. The discovery that these microbes are not up to the task calls for a reassessment of the biogeochemistry of this nitrogen pool.
Brush-like polymers with a rigidity similar to that of polymers in living cells have been synthesized and used to build force-responsive materials. The advance opens the door to applications in drug delivery and tissue engineering. See Letter p.651
Physicists have puzzled over a hidden electronic order in a uranium-based material for decades. A new theory attributes it to not just a single but a double breaking of time-reversal symmetry. See Article p.621
The development of collective long-range order by means of phase transitions occurs by the spontaneous breaking of fundamental symmetries. Magnetism is a consequence of broken time-reversal symmetry, whereas superfluidity results from broken gauge invariance. The broken symmetry that develops below 17.5 kelvin in the heavy-fermion compound URu2Si2 has long eluded such identification. Here we show that the recent observation of Ising quasiparticles in URu2Si2 results from a spinor order parameter that breaks double time-reversal symmetry, mixing states of integer and half-integer spin. Such ‘hastatic’ order hybridizes uranium-atom conduction electrons with Ising 5f2 states to produce Ising quasiparticles; it accounts for the large entropy of condensation and the magnetic anomaly observed in torque magnetometry. Hastatic order predicts a tiny transverse moment in the conduction-electron ‘sea’, a colossal Ising anisotropy in the nonlinear susceptibility anomaly and a resonant, energy-dependent nematicity in the tunnelling density of states.
Mutations in mitochondrial DNA (mtDNA) are associated with severe human diseases and are maternally inherited through the egg’s cytoplasm. Here we investigated the feasibility of mtDNA replacement in human oocytes by spindle transfer (ST; also called spindle–chromosomal complex transfer). Of 106 human oocytes donated for research, 65 were subjected to reciprocal ST and 33 served as controls. Fertilization rate in ST oocytes (73%) was similar to controls (75%); however, a significant portion of ST zygotes (52%) showed abnormal fertilization as determined by an irregular number of pronuclei. Among normally fertilized ST zygotes, blastocyst development (62%) and embryonic stem cell isolation (38%) rates were comparable to controls. All embryonic stem cell lines derived from ST zygotes had normal euploid karyotypes and contained exclusively donor mtDNA. The mtDNA can be efficiently replaced in human oocytes. Although some ST oocytes displayed abnormal fertilization, remaining embryos were capable of developing to blastocysts and producing embryonic stem cells similar to controls.
Mitochondrial DNA mutations transmitted maternally within the oocyte cytoplasm often cause life-threatening disorders. Here we explore the use of nuclear genome transfer between unfertilized oocytes of two donors to prevent the transmission of mitochondrial mutations. Nuclear genome transfer did not reduce developmental efficiency to the blastocyst stage, and genome integrity was maintained provided that spontaneous oocyte activation was avoided through the transfer of incompletely assembled spindle–chromosome complexes. Mitochondrial DNA transferred with the nuclear genome was initially detected at levels below 1%, decreasing in blastocysts and stem-cell lines to undetectable levels, and remained undetectable after passaging for more than one year, clonal expansion, differentiation into neurons, cardiomyocytes or β-cells, and after cellular reprogramming. Stem cells and differentiated cells had mitochondrial respiratory chain enzyme activities and oxygen consumption rates indistinguishable from controls. These results demonstrate the potential of nuclear genome transfer to prevent the transmission of mitochondrial disorders in humans.
The active centre of the spliceosome consists of an intricate network formed by U5, U2 and U6 small nuclear RNAs, and a pre-messenger-RNA substrate. Prp8, a component of the U5 small nuclear ribonucleoprotein particle, crosslinks extensively with this RNA catalytic core. Here we present the crystal structure of yeast Prp8 (residues 885–2413) in complex with Aar2, a U5 small nuclear ribonucleoprotein particle assembly factor. The structure reveals tightly associated domains of Prp8 resembling a bacterial group II intron reverse transcriptase and a type II restriction endonuclease. Suppressors of splice-site mutations, and an intron branch-point crosslink, map to a large cavity formed by the reverse transcriptase thumb, and the endonuclease-like and RNaseH-like domains. This cavity is large enough to accommodate the catalytic core of group II intron RNA. The structure provides crucial insights into the architecture of the spliceosome active site, and reinforces the notion that nuclear pre-mRNA splicing and group II intron splicing have a common origin.
In combination with existing observations and detailed circumstellar models, the detection of hydrogen deuteride emission from the star TW Hydrae implies a circumstellar disk mass of more than 0.05 solar masses, which is enough to form a planetary system like our own.
A layered on-chip structure of magnetic thin films is engineered to permit the vertical transfer of magnetic information over near-atomic distances.
Thermal transitions of polyisocyanide single molecules to polymer bundles and finally networks lead to hydrogels mimicking the properties of biopolymer intermediate-filament networks; their analysis shows that bundling and chain stiffness are crucial design parameters for hydrogels.
Palaeoproxy evidence shows that the sea-surface-temperature gradient across the tropical Pacific Ocean strengthened during the Medieval Warm Period but weakens in model-projected future warming; this is because solar radiation induces greater precipitation for the same temperature change than greenhouse gases.
Riverine carbon-14 measurements show that anthropogenic disturbance of peat swamp forest in southeast Asia is causing increased release of carbon that has been stored in the peat for thousands of years.
Fire ants (Solenopsis invicta) are socially polymorphic, with some workers tolerating several queens in their colony and others tolerating just one; this study shows that a non-recombining supergene is responsible for this social polymorphism, and the operation of this genomic region is remarkably similar to that of sex chromosomes.
Calcium imaging in live mice shows that a rare population of unmyelinated sensory neurons—expressing the G-protein-coupled receptor MRGPRB4—responds specifically to massage-like stroking of hairy skin, with positive reinforcing behavioural effects.
Alzheimer’s-prone mice deficient in NLRP3 or caspase-1 fail to develop learning deficits and show reduced neuropathology.
Mice expressing a constitutively active form of RagA are unable to inhibit mTORC1 after birth and to trigger autophagy, and succumb perinatally.
Lymphocyte migration in the spleen is visualized live in mice using a real-time two-photon laser-scanning microscopy approach revealing that marginal zone and follicular B cells are highly motile and can shuttle between compartments, and integrin adhesion is the key to cellular retention in the marginal zone.
Evidence for a link between cellular senescence and metabolic regulation is provided, through the observation that p53 represses the expression of malic enzymes, thereby regulating NADPH, lipid and glutamine metabolism; in turn, this repression further activates p53, promoting cellular senescence.
To identify comprehensively factors involved in RNAi and microRNA-mediated gene expression regulation, this study performed a phylogenetic analysis of 86 eukaryotic species; the candidates this approach highlighted were subjected to Bayesian analysis with transcriptional and proteomic interaction data, identifying protein orthologues of already known RNAi silencing factors, as well as other hits involved in splicing, suggesting a connection between the two processes.
The structures of three distinct human transcription factor IID (TFIID) protein assemblies are solved using cryo-electron microscopy; by incorporating TAF8 and TAF10, the key structural changes that remodel TFIID during assembly are determined, particularly the transition from a symmetric core-TFIID to an asymmetric holo-complex.
Several crystal structures of the rotary motor of bacterial V-ATPase are solved at high resolution, representing different asymmetric structures and enabling the prediction of a model for the rotational mechanism of V1-ATPase.