,  &  Planetary science: Planetary billiards (pp459-469; N&V)
A trio of papers from the same research team in this week's Nature explain three unusual features of the Solar System with a single, underlying theory.
Astronomers have come up with various explanations for why the giant planets have eccentric, tilted orbits; how Jupiter got its Trojans, which are asteroids that follow and trail the planet in its orbit; and the 'Late Heavy Bombardment' that peppered the Moon with large chunks of rubble left behind from planet formation some 700 million years earlier.
But Alessandro Morbidelli and colleagues show that all of these could be a direct result of Saturn and Jupiter shifting their orbits early in the Solar System's history. If there was a time when Saturn completed exactly one orbit of the Sun for every two orbits made by Jupiter, their gravitational interactions would be accentuated by this 'resonance'. This could elongate and tilt their orbits, and have a knock-on effect on Uranus and Neptune.
Saturn and Jupiter could have been moved into this resonance by thousands of gravitational tweaks by passing planetesimals, residues of the planets' formation. The Trojans are all that remains of these planetesimals. And when Neptune was flung outwards by the rearrangement, it sent more planetesimals hurtling towards the Sun, some of which struck our Moon.
"But caution is required," warns Joe Hahn in a related News and Views article. "The fact that a simulation of planet formation produces an end-state in good agreement with the observed Solar System does not prove that the simulated events actually happened."
Alessandro Morbidelli (Observatoire de la Cote d'Azur, CNRS, Nice, France)
Tel: + 33 4 92 00 31 26; E-mail: [email protected]
Harold F. Levison (Southwest Research Institute, Boulder, CO, USA) Co-Author
Tel: +1 303 546 9670; E-mail: [email protected]
Joe Hahn (Saint Mary's University, Halifax, Canada)
Tel: +1 902 420 5428; E-mail: [email protected]
 &  Molecular biology: Elusive plant hormone receptor identified (pp 441-451; N&V)
Over 70 years ago, researchers discovered the plant hormone, auxin, the existence of which had long been predicted, by Charles Darwin in the 1880s. But despite playing a critical role in nearly every aspect of the growth and development of a plant, the mechanism by which auxin exerts its effects has been poorly understood. Now, in this week's Nature, two articles by independent groups have identified a specific target of auxin: the elusive auxin receptor.
Approaching the problem in different ways, Stefan Kepinski and Ottoline Leyser, and Nihal Dharmasiri and colleagues found that auxin directly binds to the protein TIR1, which forms part of a complex that promotes the degradation of other proteins. By binding TIR1, auxin activates this degradation complex, causing the destruction of a family of transcriptional repressor proteins that otherwise prevent the activation of specific genes required for plant development.
In an accompanying News and Views article, Judy Callis stresses the importance of this discovery: "Let us hope that we will soon be able to answer [the children's rhyme] in the affirmative: Yes, you or I or anyone can know why oats, peas, beans and barley grow"
Ottoline O Leysr (University of York, UK) Paper 
Tel: +44 1904 328686; E-mail: [email protected]
Mark Estelle (Indiana University, Bloomington, IN, USA) Paper 
Tel: +1 812 856 1216 E-mail: [email protected]
Judy Callis (University of California-Davis, CA, USA)
Tel: +1 530 752 1015; E-mail: [email protected]
 Health: A new mechanism behind atherosclerosis (pp 502-506)
Smoking and elevated cholesterol levels have been shown to increase vascular disease, but these risk factors are absent in many cases. Now, a study appearing in this week's Nature offers proof of another mechanism behind atherosclerosis, a type of vascular disease. The study finds that abnormal metabolism in arterial walls can cause this disorder.
Clay Semenkovich and colleagues designed mice that overexpressed a gene involved in energy production from respiratory oxygen in vascular tissue, thereby disrupting the process. This caused a rise in oxidative stress in arterial walls, leading, in turn, to a rise in blood pressure and atherosclerosis. The authors suggest that nutritional strategies might be designed around this newly discovered mechanism to help fight heart disease in patients.
Clay F. Semenkovich (Washington University School of Medicine, St Louis, MO, USA)
Tel: +1 314 362 4454; E-mail: [email protected]
 Epidemiology: Cattle movements to blame for bovine TB (pp 491-496; N&V)
The ongoing outbreak of bovine tuberculosis in Britain is being driven by the movement of cattle from one part of the country to another, according to an analysis of Government livestock records. The distribution of the disease, which has been on the rise for the past twenty years, is more accurately predicted by cattle movements than by other factors, such as the presence of disease-carrying wild species.
The study uses data from the UK Cattle Tracing System, which records all transfers of livestock. Such movements are the key variable in establishing the disease in new areas, although other factors are probably needed to maintain any outbreak of the disease beyond its current stronghold in southwest England, report William Wint and colleagues in this week's Nature.
"Their work is a tour de force in the integrated statistical analysis of a set of complex databases," comments Mark Woolhouse in an accompanying News and Views article. But he adds that the role of badgers (the subject of a controversial culling study in Britain) in spreading the disease still remains poorly understood. This, he argues, underlines both the complexity of such disease outbreaks, and the length of time needed for prevention measures to work.
William Wint (Environmental Research Group Oxford Limited, Oxford, UK)
Tel: +44 1865 271 257; E-mail: [email protected]
Mark E Woolhouse (The University of Edinburgh, Scotland)
Tel: +44 131 650 7347; E-mail: [email protected]
 Materials: Bridging the boundaries (pp 475-478; N&V)
High-temperature superconductors carry more electricity if calcium ions are added, but this also lowers the useful operating temperature of the material.
Two papers, in this week's Nature and this month's Nature Materials (see Nature Materials Vol 4, 470-475, 2005), explain that calcium improves current flow because it is the right size to fill gaps between the tiny crystals that make up these superconducting materials.
Robert Klie and colleagues suggest, in Nature, that similarly sized metal ions such as silver and europium could plug the gaps just as well without reducing the critical temperature. David Larbalestier and colleagues use electron microscope measurements to show, in Nature Materials, how calcium ions can distort the crystal structure around these boundaries, while still boosting current.
In a related News and Views article in Nature Materials, Jochen Mannhart and David Muller comment: "The performance and costs of superconducting cables are mainly controlled by the boundaries between the crystallites of the superconductors."
Robert Klie (Brookhaven National Laboratory, Upton, New York, USA)
Tel: +1 631 344 7709; E-mail: [email protected]
Jocen Mannhart (University of Augsburg, Germany)
Tel: +49 821 598 3650; E-mail: [email protected]
 Visual searches for rare items can be 'disturbingly inaccurate' (pp 439-440)
Visual search tasks that involve looking for infrequently occurring objects can be fraught with errors, according to a Brief Communication in this week's Nature.
In a laboratory version of a baggage-screening task, Jeremy Wolfe and colleagues show that when the object being screened for was commonly found (present 50 per cent of the time), observers failed to identify it only 7 per cent of the time. On the other hand, when the target was rare (present 1 per cent of the time), the error rate soared to 30 per cent. The authors attribute this discrepancy to an observer's quitting threshold. With an infrequent target, observers tend to abandon searches inappropriately early, leading to more 'misses'.
In the laboratory, it is difficult to control for the influence of training and motivation. The authors argue that that field studies will be vital for determining whether real world searches that involve rare targets such as checking baggage for weapons or screening a mammogram for tumours are subject to similar problems.
Jeremy M Wolfe (Harvard Medical School, Cambridge, MA, USA)
Tel: +1 617 768 8818; E-mail: [email protected]
 And finally- Tree chemicals influence koala visits (pp 488-490)
Noxious chemicals produced by eucalyptus trees as a defence against koalas may influence the animals' populations, according to a ten-year study of koala feeding habits. Trees that produce the highest concentrations of chemicals called formylated phloroglucinol compounds (FPCs) tend to deter the creatures the most meaning that the largest, most tempting trees are often avoided.
Captive koalas (Phascolarctos cinereus) are known to avoid plants with high concentrations of these chemicals. But in the wild, other variables such as size, accessibility and risk of predation can influence a koala's choice of tree, point out Ben Moore and William Foley, who report their results in this week's Nature.
The researchers measured size, FPC concentration and nitrogen levels (an indicator of nutritional value) in two eucalyptus species, Eucalyptus globulus and E. viminalis. Larger trees generally get fewer visits from koalas than might be expected, because they contain large amounts of FPCs; medium-sized trees, meanwhile, may suffer more than their fair share of damage.
Ben D. Moore (Australian National University, Canberra, Australia currently at James Cook University, Townsville, Australia)
Tel: +61 747 814 133; E-mail: [email protected]
ALSO IN THIS ISSUE:
 A RING-type ubiquitin ligase family member required to repress follicular helper T cells and autoimmunity (pp 452-458)
 Quantum interference during high-order harmonic generation from aligned molecules (pp 470-477; N&V)
 Changes in carbon dioxide during an oceanic anoxic event linked to intrusion into Gondwana coals (pp 479-482)
 Seismological evidence for mosaic structure of the surface of the Earth's inner core (pp 483-487)
 Allosteric modulation of the presynaptic Ca2+ sensor for vesicle fusion (pp 497-501)
 Polo kinase links the stress pathway to cell cycle control and tip growth in fission yeast (pp 507-512)
 Structural basis for the regulation of tubulin by vinblastine (pp 519-522)
 Insights into microtubule nucleation from the crystal structure of human-tubulin (pp 523-527)
 Microscopic magnetic-field imaging (p 440)
ADVANCE ONLINE PUBLICATION
***This paper will be published electronically on Nature's website on 25 May at 1800 London time / 1300 US Eastern time (which is also when the embargo lifts) as part of our AOP (ahead of print) programme. Although we have included it on this release to avoid multiple mailings it will not appear in print on 26 May, but at a later date.***
 Ultrafast non-thermal control of magnetization by instantaneous photomagnetic pulses