Mutations in SLC6A19, encoding B0AT1, cause Hartnup disorder

Hartnup disorder, an autosomal recessive defect named after an English family described in 1956 (ref. 1), results from impaired transport of neutral amino acids across epithelial cells in renal proximal tubules and intestinal mucosa. Symptoms include transient manifestations of pellagra (rashes), cerebellar ataxia and psychosis. Using homozygosity mapping in the original family in whom Hartnup disorder was discovered, we confirmed that the critical region for one causative gene was located on chromosome 5p15 (ref. 3). This region is homologous to the area of mouse chromosome 13 that encodes the sodium-dependent amino acid transporter B(0)AT1 (ref. 4). We isolated the human homolog of B(0)AT1, called SLC6A19, and determined its size and molecular organization. We then identified mutations in SLC6A19 in members of the original family in whom Hartnup disorder was discovered and of three Japanese families. The protein product of SLC6A19, the Hartnup transporter, is expressed primarily in intestine and renal proximal tubule and functions as a neutral amino acid transporter.     

Further morphological and molecular studies of driftwood hoppers (Crustacea: Amphipoda: Talitridae) from Mediterranean/north-east Atlantic coastlines

An unknown talitrid was discovered in 2011 in the Swale, UK, living in driftwood. Sequencing of multiple mitochondrial and nuclear genes (cytochrome oxidase I, 18S rDNA and 28S rDNA) confirms that the unknown taxon was close to Orchestia mediterranea A. Costa 1857. The driftwood in which it was found was of Douglas fir (Pseudotsuga menziesii), probably imported from North America. Relative growth methods allow us to reject the null hypothesis that the unknown taxon was a juvenile Orchestia mediterranea. This is because the unknown taxon initiates sexual maturation at an earlier moult number (neoteny) and is predicted to reach terminal moult stages at a much smaller size (dwarfism) than its closest relative O. mediterranea. Both molecular and morphological data confirm that the unknown taxon from the Swale, UK, is a new driftwood specialist taxon, distantly related to the driftwood specialist genus Macarorchestia. Additional data for body length and sex ratios are presented for Macarorchestia. In addition, relative growth methods have shown that the driftwood species Orchestia microphtalma Amanieu and Salvat 1964 is closer to the genus Macarorchestia rather than to the wrack generalist one, Orchestia. This evidence is in line with the molecular results that do not cluster morphologically defined species of Orchestia monophyletically.     

A New‐Keynesian DSGE model for forecasting the South African economy

This paper develops a New‐Keynesian Dynamic Stochastic General Equilibrium (NKDSGE) model for forecasting the growth rate of output, inflation, and the nominal short‐term interest rate (91 days Treasury Bill rate) for the South African economy. The model is estimated via maximum likelihood technique for quarterly data over the period of 1970:1–2000:4. Based on a recursive estimation using the Kalman filter algorithm, out‐of‐sample forecasts from the NKDSGE model are compared with forecasts generated from the classical and Bayesian variants of vector autoregression (VAR) models for the period 2001:1–2006:4. The results indicate that in terms of out‐of‐sample forecasting, the NKDSGE model outperforms both the classical and Bayesian VARs for inflation, but not for output growth and nominal short‐term interest rate. However, differences in RMSEs are not significant across the models. Copyright © 2008 John Wiley & Sons, Ltd.     

学习成果分析:一个教学计划设计的分析

This paper describes an analysis of the match between the module learning outcomes and the programme learning outcomes of the MSc in Assistive Technology offered by the School of Computing. The contribution of each MSc module to the overall programme learning outcomes was assessed using a Module Matrix. An overall Master Matrix was used to assess the overall contribution of all 16 modules to the programme learning outcomes of the MSc programme. The analysis of the MSc programme design was taken a stage further by graphing the learning outcomes of the overall programme against the individual module learning outcomes. This provided a useful tool for analysis of the MSc programme. The approach outlined in this paper provides a visualisation tool that allows the programme designer to quickly identify the deficiencies and excesses in the relationships between programme learning outcomes and module learning outcomes.     

The DNA sequence and biology of human chromosome 19

Chromosome 19 has the highest gene density of all human chromosomes, more than double the genome-wide average. The large clustered gene families, corresponding high G + C content, CpG islands and density of repetitive DNA indicate a chromosome rich in biological and evolutionary significance. Here we describe 55.8 million base pairs of highly accurate finished sequence representing 99.9% of the euchromatin portion of the chromosome. Manual curation of gene loci reveals 1,461 protein-coding genes and 321 pseudogenes. Among these are genes directly implicated in mendelian disorders, including familial hypercholesterolaemia and insulin-resistant diabetes. Nearly one-quarter of these genes belong to tandemly arranged families, encompassing more than 25% of the chromosome. Comparative analyses show a fascinating picture of conservation and divergence, revealing large blocks of gene orthology with rodents, scattered regions with more recent gene family expansions and deletions, and segments of coding and non-coding conservation with the distant fish species Takifugu.     

An early lunar core dynamo driven by thermochemical mantle convection

Although the Moon currently has no internally generated magnetic field, palaeomagnetic data, combined with radiometric ages of Apollo samples, provide evidence for such a magnetic field from approximately 3.9 to 3.6 billion years (Gyr) ago, possibly owing to an ancient lunar dynamo. But the presence of a lunar dynamo during this time period is difficult to explain, because thermal evolution models for the Moon yield insufficient core heat flux to power a dynamo after approximately 4.2 Gyr ago. Here we show that a transient increase in core heat flux after an overturn of an initially stratified lunar mantle might explain the existence and timing of an early lunar dynamo. Using a three-dimensional spherical convection model, we show that a dense layer, enriched in radioactive elements (a 'thermal blanket'), at the base of the lunar mantle can initially prevent core cooling, thereby inhibiting core convection and magnetic field generation. Subsequent radioactive heating progressively increases the buoyancy of the thermal blanket, ultimately causing it to rise back into the mantle. The removal of the thermal blanket, proposed to explain the eruption of thorium- and titanium-rich lunar mare basalts, plausibly results in a core heat flux sufficient to power a short-lived lunar dynamo.     

Indian and African plate motions driven by the push force of the Réunion plume head

Mantle plumes are thought to play an important part in the Earth's tectonics, yet it has been difficult to isolate the effect that plumes have on plate motions. Here we analyse the plate motions involved in two apparently disparate events--the unusually rapid motion of India between 67 and 52 million years ago and a contemporaneous, transitory slowing of Africa's motion--and show that the events are coupled, with the common element being the position of the Indian and African plates relative to the location of the Réunion plume head. The synchroneity of these events suggests that they were both driven by the force of the Réunion plume head. The recognition of this plume force has substantial tectonic implications: the speed-up and slowdown of India, the possible cessation of convergence between Africa and Eurasia in the Palaeocene epoch and the enigmatic bends of the fracture zones on the Southwest Indian Ridge can all be attributed to the Réunion plume.