Review, News & Views, Perspectives, Hypotheses and Analyses in 2013

A spectroscopic technique has been demonstrated that uses stimulated emission to enhance weak X-ray signals for fundamental studies in materials science. See Letter p.191

Autophagy, the process of cellular self-cannibalism, comes in various forms. It now emerges that two of these — mitophagy and xenophagy — share a common initiator protein, Parkin. See Article p.512

Cellular cross-talk, enzymatic catalysis and regulation of gene expression all depend on molecular recognition. A method that allows the design of proteins with desired recognition sites could thus be revolutionary. See Letter p.212

Vision requires the continuous recycling of photobleached pigments. An atypical form of a degradative pathway called autophagy seems to participate in this process in retinal pigment epithelial cells.

A cost-effective architecture for quantum cryptography has been demonstrated in which a single receiver positioned at a network-hub node is shared by many end users to exchange secret encryption keys. See Letter p.69

Fingerprints of sulphur isotopes in rocks from the ridge beneath the Atlantic Ocean suggest that a substantial fraction of sulphur at Earth's surface is left over from the formation of the planet's core. See Letter p.208

Host-cell detection of lipopolysaccharide in the outer membrane of Gram-negative bacteria was thought to be restricted to the cell-surface receptor TLR4. It emerges that lipopolysaccharide can also be sensed in the cytoplasm.

Morphological mimicry among organisms has long been recognized as an adaptive strategy, but mimicry also occurs at the molecular level. One emerging example is microbial pathogens' use of structural mimics that engage host-cell receptors.

An analysis of northern ecosystems shows that the effects on plant growth of rising night-time temperatures are opposite to those of increasing daytime temperatures — a finding that has implications for carbon-cycle models. See Letter p.88

Topoisomerase enzymes facilitate gene transcription by resolving DNA tangles. Malfunction of these enzymes seems to compromise the expression of very long genes, potentially mediating neurodevelopmental disorders. See Article p.58

We thought we had figured out dopamine, a neuromodulator involved in everything from learning to addiction. But the finding that dopamine levels ramp up as rats navigate to a reward may overthrow current theories. See Letter p.575

A study shows that stem cells can be used to generate self-organizing three-dimensional tissues that mimic the developing human brain. These tissues provide a tool for modelling neurodevelopmental disorders. See Article p.373

The observation of infrared emission following a short γ-ray burst lends support to the hypothesis that mergers of compact binary systems cause such bursts and produce the heaviest nuclei in the cosmos. See Letter p.547

Massive stars, with masses ten or more times that of the Sun, dominate our Universe. Theories of how these stars form are now being challenged by observations of a collapsing cloud of gas and dust.

People whose guts contain a low diversity of bacteria are found to have higher levels of body fat and inflammation than those with high gut-microbial richness. But dietary intervention can help. See Article p.541 & Letter p.585

The far-reaching effects of the relationship between an animal and its resident gut microorganisms are becoming ever clearer. New findings suggest it can even create barriers that keep species separate.

Herbivory and mechanical wounding in plants have been shown to elicit electrical signals — mediated by two glutamate-receptor-like proteins — that induce defence responses at local and distant sites. See Article p.422

During infection, the inflammatory immune response can cause pain by activating nociceptor neurons. A bacterial pathogen also seems to stimulatepain directly, modulating the immune response in its favour. See Article p.52

A correlation between stellar brightness variations and the gravitational acceleration at a star's surface has been observed that allows this acceleration to be measured with a precision of better than 25%. See Letter p.427