Sophisticated particle-feeding in a large Early Cambrian crustacean

Most Cambrian arthropods employed simple feeding mechanisms requiring only low degrees of appendage differentiation. In contrast, post-Cambrian crustaceans exhibit a wide diversity of feeding specializations and possess a vast ecological repertoire. Crustaceans are evident in the Cambrian fossil record, but have hitherto been known exclusively from small individuals with limited appendage differentiation. Here we describe a sophisticated feeding apparatus from an Early Cambrian arthropod that had a body length of several centimetres. Details of the mouthparts resolve this taxon as a probable crown-group (pan)crustacean, while its feeding style, which allowed it to generate and handle fine food particles, significantly expands the known ecological capabilities of Cambrian arthropods. This Early Cambrian record predates the major expansions of large-bodied, particle-handling crustaceans by at least one hundred million years, emphasizing the importance of ecological context in driving adaptive radiations.     

Jovian-like aurorae on Saturn

Planetary aurorae are formed by energetic charged particles streaming along the planet's magnetic field lines into the upper atmosphere from the surrounding space environment. Earth's main auroral oval is formed through interactions with the solar wind, whereas that at Jupiter is formed through interactions with plasma from the moon Io inside its magnetic field (although other processes form aurorae at both planets). At Saturn, only the main auroral oval has previously been observed and there remains much debate over its origin. Here we report the discovery of a secondary oval at Saturn that is approximately 25 per cent as bright as the main oval, and we show this to be caused by interaction with the middle magnetosphere around the planet. This is a weak equivalent of Jupiter's main oval, its relative dimness being due to the lack of as large a source of ions as Jupiter's volcanic moon Io. This result suggests that differences seen in the auroral emissions from Saturn and Jupiter are due to scaling differences in the conditions at each of these two planets, whereas the underlying formation processes are the same.     

Temporal precision in the neural code and the timescales of natural vision

The timing of action potentials relative to sensory stimuli can be precise down to milliseconds in the visual system, even though the relevant timescales of natural vision are much slower. The existence of such precision contributes to a fundamental debate over the basis of the neural code and, specifically, what timescales are important for neural computation. Using recordings in the lateral geniculate nucleus, here we demonstrate that the relevant timescale of neuronal spike trains depends on the frequency content of the visual stimulus, and that 'relative', not absolute, precision is maintained both during spatially uniform white-noise visual stimuli and naturalistic movies. Using information-theoretic techniques, we demonstrate a clear role of relative precision, and show that the experimentally observed temporal structure in the neuronal response is necessary to represent accurately the more slowly changing visual world. By establishing a functional role of precision, we link visual neuron function on slow timescales to temporal structure in the response at faster timescales, and uncover a straightforward purpose of fine-timescale features of neuronal spike trains.     

The genome sequence of the rice blast fungus Magnaporthe grisea

Magnaporthe grisea is the most destructive pathogen of rice worldwide and the principal model organism for elucidating the molecular basis of fungal disease of plants. Here, we report the draft sequence of the M. grisea genome. Analysis of the gene set provides an insight into the adaptations required by a fungus to cause disease. The genome encodes a large and diverse set of secreted proteins, including those defined by unusual carbohydrate-binding domains. This fungus also possesses an expanded family of G-protein-coupled receptors, several new virulence-associated genes and large suites of enzymes involved in secondary metabolism. Consistent with a role in fungal pathogenesis, the expression of several of these genes is upregulated during the early stages of infection-related development. The M. grisea genome has been subject to invasion and proliferation of active transposable elements, reflecting the clonal nature of this fungus imposed by widespread rice cultivation.     

Estimating private information usage amongst analysts: evidence from UK earnings forecasts

This paper introduces a methodology for estimating the likelihood of private information usage amongst earnings analysts. This is achieved by assuming that one group of analysts generate forecasts based on the underlying dynamics of earnings, while all other analysts are assumed to issue forecasts based on the prevailing consensus forecast. Given this behavioural dichotomy, we are able to derive (and estimate) a structural econometric model of forecast behaviour, which has implications regarding the determinants of analysts' private information endowments and forecast accuracy over the forecast horizon. Copyright © 2010 John Wiley & Sons, Ltd.     

Forecast accuracy and effort: The case of US inflation rates

This paper investigates the relationship between forecast accuracy and effort, where effort is defined as the number of times the model used to generate forecasts is recursively estimated over the full sample period. More specifically, within a framework of costly effort, optimal effort strategies are derived under the assumption that the dynamics of the variable of interest follow an autoregressive‐type process. Results indicate that the strategies are fairly robust over a wide range of linear and nonlinear processes (including structural break processes), and deliver forecasts of transitory, core and total inflation that require less effort to generate and are as accurate as (that is, are insignificantly different from) those produced with maximum effort. Copyright © 2010 John Wiley & Sons, Ltd.     

Early research on the biological effects of microwave radiation: 1940–1960

Two overriding considerations shaped the development of early research on the biological effects of microwave radiation—possible medical application (diathermy) and uncertainty about the hazards of exposure to radar. Reports in the late 1940s and early 1950s of hazards resulting from microwave exposure led to the near abandonment of medical research related to microwave diathermy at the same time that military and industrial concern over hazards grew, culminating in the massive research effort known as ‘the Tri-Service program’ (1957–1960). Both the early focus on medical application and the later search for hazards played important roles in dictating how this field of research developed as a science.     

A P-type ATPase required for rice blast disease and induction of host resistance

To cause diseases in plants, pathogenic microorganisms have evolved mechanisms to deliver proteins directly into plant cells, where they suppress plant defences and facilitate tissue invasion. How plant pathogenic fungi, which cause many of the world's most serious plant diseases, deliver proteins during plant infection is currently unknown. Here we report the characterization of a P-type ATPase-encoding gene, MgAPT2, in the economically important rice blast pathogen Magnaporthe grisea, which is required for exocytosis during plant infection. Targeted gene replacement showed that MgAPT2 is required for both foliar and root infection by the fungus, and for the rapid induction of host defence responses in an incompatible reaction. DeltaMgapt2 mutants are impaired in the secretion of a range of extracellular enzymes and accumulate abnormal Golgi-like cisternae. However, the loss of MgAPT2 does not significantly affect hyphal growth or sporulation, indicating that the establishment of rice blast disease involves the use of MgApt2-dependent exocytotic processes that operate during plant infection.