Natural variation for sulfate content in Arabidopsis thaliana is highly controlled by APR2

Most agronomic traits of importance, whether physiological (such as nutrient use efficiency) or developmental (such as flowering time), are controlled simultaneously by multiple genes and their interactions with the environment. Here, we show that variation in sulfate content between wild Arabidopsis thaliana accessions Bay-0 and Shahdara is controlled by a major quantitative trait locus that results in a strong interaction with nitrogen availability in the soil. Combining genetic and biochemical results and using a candidate gene approach, we have cloned the underlying gene, showing how a single-amino acid substitution in a key enzyme of the assimilatory sulfate reduction pathway, adenosine 5'-phosphosulfate reductase, is responsible for a decrease in enzyme activity, leading to sulfate accumulation in the plant. This work illustrates the potential of natural variation as a source of new alleles of known genes, which can aid in the study of gene function and metabolic pathway regulation. Our new insights on sulfate assimilation may have an impact on sulfur fertilizer use and stress defense improvement.     

Global Optimization in Any Minkowski Metric: A Permutation-Translation Simulated Annealing Algorithm for Multidimensional Scaling

It is well known that considering a non-Euclidean Minkowski metric in Multidimensional Scaling, either for the distance model or for the loss function, increases the computational problem of local minima considerably. In this paper, we propose an algorithm in which both the loss function and the composition rule can be considered in any Minkowski metric, using a multivariate randomly alternating Simulated Annealing procedure with permutation and translation phases. The algorithm has been implemented in Fortran and tested over classical and simulated data matrices with sizes up to 200 objects. A study has been carried out with some of the common loss functions to determine the most suitable values for the main parameters. The experimental results confirm the theoretical expectation that Simulated Annealing is a suitable strategy to deal by itself with the optimization problems in Multidimensional Scaling, in particular for City-Block, Euclidean and Infinity metrics.     

The role of dyking and fault control in the rapid onset of eruption at Chaitén volcano, Chile

Rhyolite is the most viscous of liquid magmas, so it was surprising that on 2?May 2008 at Chaitén Volcano, located in Chile's southern Andean volcanic zone, rhyolitic magma migrated from more than 5?km depth in less than 4?hours (ref.?1) and erupted explosively with only two days of detected precursory seismic activity. The last major rhyolite eruption before that at Chaitén was the largest volcanic eruption in the twentieth century, at Novarupta volcano, Alaska, in 1912. Because of the historically rare and explosive nature of rhyolite eruptions and because of the surprisingly short warning before the eruption of the Chaitén volcano, any information about the workings of the magmatic system at Chaitén, and rhyolitic systems in general, is important from both the scientific and hazard perspectives. Here we present surface deformation data related to the Chaitén eruption based on radar interferometry observations from the Japan Aerospace Exploration Agency (JAXA) DAICHI (ALOS) satellite. The data on this explosive rhyolite eruption indicate that the rapid ascent of rhyolite occurred through dyking and that melt segregation and magma storage were controlled by existing faults.     

Institutional experience of PTH evaluation on fine-needle washing after aspiration biopsy to locate hyperfunctioning parathyroid tissue

Assaying parathyroid hormone (PTH) in the washing liquid after fine-needle aspiration biopsy (FNAB) seems to be a valid approach to locate parathyroid tissue. PTH-FNAB was evaluated in 47 patients with a clinical picture of primary hyperparathyroidism (PHP) and ultrasonography (US) suggestive of parathyroid lesion. The patients were subdivided into two groups on the basis of the absence or presence of US thyroid alterations. The result of PTH-FNAB was compared with those of cytology, scintigraphy and, in 24 patients, surgical outcome. PTH-FNAB samples with a value higher than that recorded in the serum and higher than our institutional cut-off were deemed to be probable samples of parathyroid tissue. Cytology proved diagnostic for benign thyroid lesions, non-diagnostic for thyroid lesions, hyperplastic parathyroid tissue, undetermined or malignant thyroid lesions and other lesions in 45%, 30%, 17%, 4%, and 4% of cases, respectively. In 47% of cases, PTH-FNAB indicated that the sample had been taken in parathyroid tissue. In patients without US alterations, the diagnostic accuracy of PTH-FNAB was greater than that of scintigraphy. After surgery, comparison between the results of PTH-FNAB and scintigraphy, in terms of positive predictive value (PPV), revealed the superiority of PTH-FNAB; PPV was 94% for FNAB and 71% for scintigraphy, while sensitivity was 83% and 69%, respectively. PTH-FNAB evaluation after FNAB appears to be more diagnostic than cytology and scintigraphy. Of all the procedures used, PTH-FNAB appears to be the method of choice when the target is US suggestive and reachable. PTH-FNAB appears to be a useful method of guiding surgical intervention.     

Mutations in the polyglutamine binding protein 1 gene cause X-linked mental retardation

We found mutations in the gene PQBP1 in 5 of 29 families with nonsyndromic (MRX) and syndromic (MRXS) forms of X-linked mental retardation (XLMR). Clinical features in affected males include mental retardation, microcephaly, short stature, spastic paraplegia and midline defects. PQBP1 has previously been implicated in the pathogenesis of polyglutamine expansion diseases. Our findings link this gene to XLMR and shed more light on the pathogenesis of this common disorder.     

Neurogenic effects of β-amyloid in the choroid plexus epithelial cells in Alzheimer’s disease

β-amyloid (Aβ) can promote neurogenesis, both in vitro and in vivo, by inducing neural progenitor cells to differentiate into neurons. The choroid plexus in Alzheimer’s disease (AD) is burdened with amyloid deposits and hosts neuronal progenitor cells. However, neurogenesis in this brain tissue is not firmly established. To investigate this issue further, we examined the effect of Aβ on the neuronal differentiation of choroid plexus epithelial cells in several experimental models of AD. Here we show that Aβ regulates neurogenesis in vitro in cultured choroid plexus epithelial cells as well as in vivo in the choroid plexus of APP/Ps1 mice. Treatment with oligomeric Aβ increased proliferation and differentiation of neuronal progenitor cells in cultured choroid plexus epithelial cells, but decreased survival of newly born neurons. These Aβ-induced neurogenic effects were also observed in choroid plexus of APP/PS1 mice, and detected also in autopsy tissue from AD patients. Analysis of signaling pathways revealed that pre-treating the choroid plexus epithelial cells with specific inhibitors of TyrK or MAPK diminished Aβ-induced neuronal proliferation. Taken together, our results support a role of Aβ in proliferation and differentiation in the choroid plexus epithelial cells in Alzheimer’s disease.     

Mechanical forces in lymphatic vascular development and disease

The lymphatic vasculature is essential for fluid homeostasis and transport of immune cells, inflammatory molecules, and dietary lipids. It is composed of a hierarchical network of blind-ended lymphatic capillaries and collecting lymphatic vessels, both lined by lymphatic endothelial cells (LECs). The low hydrostatic pressure in lymphatic capillaries, their loose intercellular junctions, and attachment to the surrounding extracellular matrix (ECM) permit passage of extravasated blood plasma from the interstitium into the lumen of the lymphatic capillaries. It is generally thought that interstitial fluid accumulation leads to a swelling of the ECM, to which the LECs of lymphatic capillaries adhere, for example via anchoring filaments. As a result, LECs are pulled away from the vascular lumen, the junctions open, and fluid enters the lymphatic vasculature. The collecting lymphatic vessels then gather the plasma fluid from the capillaries and carry it through the lymph nodes to the blood circulation. The collecting vessels contain intraluminal bicuspid valves that prevent fluid backflow, and are embraced by smooth muscle cells that contribute to fluid transport. Although the lymphatic vessels are regular subject to mechanical strain, our knowledge of its influence on lymphatic development and pathologies is scarce. Here, we discuss the mechanical forces and molecular mechanisms regulating lymphatic vascular growth and maturation in the developing mouse embryo. We also consider how the lymphatic vasculature might be affected by similar mechanomechanisms in two pathological processes, namely cancer cell dissemination and secondary lymphedema.     

以龙舌兰蔗渣作为还原剂使磁铁矿精矿有效地金属化

The reduction behavior and metallization degree of magnetite concentrate with agave bagasse were investigated in an inert atmosphere. The effects of temperature, biomass content, and residence time on reduction experiments and metallization degree were investigated by X-ray diffraction and scanning electron microscopy. Compared with other types of biomass, agave bagasse had lower contents of nitrogen, sulfur, and ash. X-ray diffraction analysis showed that the metallization degree improved with increasing temperature and biomass content. Complete metallization was achieved at 1100°C for 30 min with 65:35 and 50:50 ratios of the magnetite concentrate to the agave bagasse. These results demonstrate that agave bagasse promotes the efficient metallization of magnetite concentrate without the external addition of a reducing agent. Therefore, this biomass is a technical suitable alternative to replace fossil fuels in steelmaking.     

Suppression of antibody formation against sendai virus in the SV40 and adenovirus 16 infected hamsters

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