Reviews & Analysis

Synthetic chemistry has long been used to prepare useful compounds — especially those that are hard to obtain from natural sources. But synthetic biology is coming of age as an alternative strategy. A biologist and two chemists debate the merits of their fields' synthetic prowess.

Fossils found in rocks of the Ediacaran period in Australia have been previously characterized as early marine organisms. But a report suggests that these rocks are fossilized soils. So did some of these Ediacaran organisms in fact live on land, like lichens? A palaeontologist and a geologist weigh up the evidence. See Letter p.89

A phylogenetic reconstruction of the diversification of birds across space and time provides a novel resource for evolutionary studies. But the methods used to construct this tree, and what insights can be inferred from it, are a source of debate. Two evolutionary biologists provide opinions on how to draw the lines. See Letter p.444

Anthropogenic aerosols in the atmosphere undoubtedly influence climate. But do the approaches taken in climate models to account for the effects of aerosols provide meaningful estimates of those effects? Two climate scientists offer their opinions.

The Encyclopedia of DNA Elements (ENCODE) project dishes up a hearty banquet of data that illuminate the roles of the functional elements of the human genome. Here, six scientists describe the project and discuss how the data are influencing research directions across many fields. See Articles p.57, p.75, p.83, p.91, p.101 & Letter p.109

New research backs the contentious idea that solid tumours are not masses of equivalent cells, but instead contain cancer stem cells that support tumour maintenance. Here, two experts provide complementary views on the findings and on the implications for potential therapies. See Letters p.522 & p.527

Predicting plant responses to increasing temperatures is integral to assessing the global impact of climate change. But the authors of a comparative study assert that warming experiments may not accurately reflect observational data. Climate and ecosystem scientists discuss how impact prediction should proceed. See Letter p.494

A meta-analysis of agricultural systems shows that organic yields are mostly lower than those from conventional farming, but that organic crops perform well in some contexts. Agricultural scientists discuss whether the conclusions of the study should change farming practices and management. See Letter p.229

An article suggesting that allergic responses may not be an accident of an off-target immune system, but rather a deliberate defence against potential harm, provokes the question of whether our understanding of allergy needs an overhaul. Immunologists provide their opinions. See Perspective p.465

An analysis of the intensity and polarization of sunlight reflected by Earth reveals signatures of life on our planet. What prospects are there for using similar measurements to find life on planets outside the Solar System? Planetary scientists offer some answers. See Letter p.64

In the cell, genomic DNA is transcribed into various types of RNA. But not all RNAs are translated into proteins. Does this give protein-coding RNAs greater credibility in terms of function? Views differ.

Purkinje cells in the brain region known as the cerebellum act by inhibiting their target neurons. A paper in this issue provides an explanation for how this inhibition might be used to control the timing of action potentials. But experts are not equally convinced about the functional relevance of this finding. See Letter p.502