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The week in science: Polio declared international health emergency; UK considers lifting confidentiality on animal research; and RIKEN panel dogged by further misconduct allegations.
Since the birth of synthetic biology nearly 15 years ago, the field has splintered into diverse tribes of scientists, all attempting to bestow cells with new abilities.
Sound artist Daniel Jones creates self-generating artworks based on human and natural patterns and processes. As he prepares to travel through four UK forests with the installation Living Symphonies, a collaboration with artist James Bulley, he talks about music that emerges from ecosystem dynamics, and works inspired by bacterial genetics and social networks.
Synthetic biology involves the creation of biological systems for new applications by modifying and reassembling biological components. Two views are presented here on the best way to engineer these components so that they reliably generate organisms with desired traits.
Observational data and modelling show that the rapid warming of the northeastern Canada and Greenland sector of the Arctic over the past three decades has been strongly driven by cooling in the tropical Pacific Ocean. See Letter p.209
One aim of synthetic biology is to generate complex synthetic organisms. Now, a stage in this process has been achieved in yeast cells — an entire yeast chromosome has been converted to a synthetic sequence in a stepwise manner.
A numerical simulation of cosmic structure formation reproduces both large- and smaller-scale features of a representative volume of the Universe from early in its history to the present day. See Article p.177
Data from Himalayan songbirds suggest that the rate-limiting step in biodiversity production may not be the speed of speciation, but rather the speed at which new niches are created. See Letter p.222
Field experiments that varied the composition of both plant litter and the organisms that break it down have revealed that, across ecosystems, lower biodiversity slows the rate of litter decomposition. See Letter p.218
A tour de force of X-ray scattering has yielded structures of a phytochrome photoreceptor in its dark and illuminated states, showing how localized protein refolding magnifies a light signal to form a cellular message. See Letter p.245
A simulation that starts 12 million years after the Big Bang and traces 13 billion years of cosmic evolution yields a reasonable population of elliptical and spiral galaxies, reproduces the observed distribution of galaxies in clusters and the characteristics of hydrogen on large scales, and at the same time matches the ‘metal’ and hydrogen content of galaxies on small scales.
Bariatric surgical procedures, such as vertical sleeve gastrectomy (VSG), are the most effective therapy for the treatment of obesity; now bile acids, and the presence of the nuclear bile acid receptor FXR, are shown to underpin the mechanism of VSG action, and the ability of VSG to reduce body weight and improve glucose tolerance is substantially reduced if FXR is absent.
Populations of astrocytes in the spinal cord are shown to express region-specific genes, with ventral astrocyte-encoded Sema3a necessary for proper motor neuron circuit organization and typical sensory afferent projection patterns; these findings suggest that astrocytes provide a positional cue for maintaining proper circuit formation and refinement.
This study reveals a role for the MHC class I molecule H2-Db in retinogeniculate synapse elimination; expression of this immune system molecule in neurons lacking it is sufficient to rescue proper synapse pruning, as well as the segregation of eye-specific circuits in mice.
Circularly polarized light is unexpectedly detected in the afterglow of γ-ray burst GRB 121024A measured 0.15 days after the burst, and is shown to be intrinsic to the afterglow and unlikely to be produced by dust scattering or plasma propagation effects.
The transition between ‘static’ and ‘dynamic’ friction in a model system is found to be quantitatively captured by the same theoretical framework as is used to describe brittle fracture, but deviations from this correspondence are observed as the rupture velocity approaches the speed at which sound waves propagate along the interface.
Human-induced climate change is usually assumed to be responsible for the dramatic thawing of glaciers since the mid 1990s in Greenland and northeastern Canada; approximately half of the observed warming in this region during this period is now found to be attributable to atmospheric circulation changes that may be of natural origin.
Field experiments across aquatic and terrestrial ecosystems show that biodiversity positively affects carbon and nitrogen cycling in leaf litter decomposition, indicating that reduced decomposition caused by biodiversity loss would modify the global carbon cycle and limit the nitrogen supply to the organisms at the base of the food chain.
In Himalayan songbirds, the speciation rate is ultimately set by ecological competition, rather than by the rate of acquisition of reproductive isolation.
Intracellular recordings distinguish between mechanisms that can account for variability in primary visual cortex of alert primates, consistent with a scheme in which spiking is driven by infrequent synchronous events during fixation, with sensory stimulation shifting the cortex to an asynchronous state.
The intracellular bacterial pathogen Listeria monocytogenes is shown to exploit efferocytosis—the process by which dead or dying cells are removed by phagocytosis—to promote cell-to-cell spread during infection.
The leucine-rich repeat protein NRROS which resides in the endoplasmic reticulum regulates phagocytic NADPH oxidase, minimizing collateral tissue damage caused by reactive oxygen species during inflammatory processes.
The endo-lysosomal transporters SLC15A3 and SLC15A4 provide a portal of entry for extracellular bacterial products that activate the cytoplasmic sensor NOD2; these results establish the importance of endosomes as signalling platforms specialized for triggering innate immune responses.
The solution and crystal structures of a bacterial phytochrome photosensory core in both its resting and activated states are determined; switching between closed (resting) and open (activated) forms is found to be mediated by a conserved ‘tongue’, and the structures indicate that smaller changes in the vicinity of the chromophore are amplified in scale as they are transmitted through the tongue and beyond.
