Disruption of calcitonin gene-related peptide signaling accelerates muscle denervation and dampens cytotoxic neuroinflammation in SOD1 mutant mice

Amyotrophic lateral sclerosis (ALS) is a fatal motor neuron disease. Neuronal vacuolization and glial activation are pathologic hallmarks in the superoxide dismutase 1 (SOD1) mouse model of ALS. Previously, we found the neuropeptide calcitonin gene-related peptide (CGRP) associated with vacuolization and astrogliosis in the spinal cord of these mice. We now show that CGRP abundance positively correlated with the severity of astrogliosis, but not vacuolization, in several motor and non-motor areas throughout the brain. SOD1 mice harboring a genetic depletion of the βCGRP isoform showed reduced CGRP immunoreactivity associated with vacuolization, while motor functions, body weight, survival, and astrogliosis were not altered. When CGRP signaling was completely disrupted through genetic depletion of the CGRP receptor component, receptor activity-modifying protein 1 (RAMP1), hind limb muscle denervation, and loss of muscle performance were accelerated, while body weight and survival were not affected. Dampened neuroinflammation, i.e., reduced levels of astrogliosis in the brain stem already in the pre-symptomatic disease stage, and reduced microgliosis and lymphocyte infiltrations during the late disease phase were additional neuropathology features in these mice. On the molecular level, mRNA expression levels of brain-derived neurotrophic factor (BDNF) and those of the anti-inflammatory cytokine interleukin 6 (IL-6) were elevated, while those of several pro-inflammatory cytokines found reduced in the brain stem of RAMP1-deficient SOD1 mice at disease end stage. Our results thus identify an important, possibly dual role of CGRP in ALS pathogenesis.     

复合型土壤营养调理剂改良吉林省西部风砂土的试验研究

通过两年的盆栽试验,考察了8种风砂土营养调理剂对白菜生长的影响.结果表明,与单施无机化肥相比,同时施用无机化肥与泥炭或腐泥或其混合物或腐植酸液体肥,白菜的生长高度、最大叶宽、鲜重和干重都得到了提高;单施无机化肥或共同施用无机化肥和腐植酸液体肥对当年白菜生长效果显著,第二年白菜生长明显下降;用泥炭、腐泥或其混合物改良风砂土后,再施用无机化肥,不仅当年作物生长好于单施无机化肥的,而且具有后效性.由此可见,有机物料泥炭、腐泥与无机化肥等制成的有机无机复合型土壤营养调理剂,具有改良土壤结构、提供营养,兼有长效与短效双重功能,是风砂土改良的最佳选择.     

Liquid marbles.

The transport of a small amount of liquid on a solid is not a simple process, owing to the nature of the contact between the two phases. Setting a liquid droplet in motion requires non-negligible forces (because the contact-angle hysteresis generates a force opposing the motion), and often results in the deposition of liquid behind the drop. Different methods of levitation-electrostatic, electromagnetic, acoustic, or even simpler aerodynamic techniques-have been proposed to avoid this wetting problem, but all have proved to be rather cumbersome. Here we propose a simple alternative, which consists of encapsulating an aqueous liquid droplet with a hydrophobic powder. The resulting 'liquid marbles' are found to behave like a soft solid, and show dramatically reduced adhesion to a solid surface. As a result, motion can be generated using gravitational, electrical and magnetic fields. Moreover, because the viscous friction associated with motion is very small, we can achieve quick displacements of the droplets without any leaks. All of these features are of potential benefit in microfluidic applications, and also permit the study of a drop in a non-wetting situation-an issue of renewed interest following the recent achievement of super-hydrophobic substrates.     

Chiral magnetic order at surfaces driven by inversion asymmetry

Chirality is a fascinating phenomenon that can manifest itself in subtle ways, for example in biochemistry (in the observed single-handedness of biomolecules) and in particle physics (in the charge-parity violation of electroweak interactions). In condensed matter, magnetic materials can also display single-handed, or homochiral, spin structures. This may be caused by the Dzyaloshinskii-Moriya interaction, which arises from spin-orbit scattering of electrons in an inversion-asymmetric crystal field. This effect is typically irrelevant in bulk metals as their crystals are inversion symmetric. However, low-dimensional systems lack structural inversion symmetry, so that homochiral spin structures may occur. Here we report the observation of magnetic order of a specific chirality in a single atomic layer of manganese on a tungsten (110) substrate. Spin-polarized scanning tunnelling microscopy reveals that adjacent spins are not perfectly antiferromagnetic but slightly canted, resulting in a spin spiral structure with a period of about 12 nm. We show by quantitative theory that this chiral order is caused by the Dzyaloshinskii-Moriya interaction and leads to a left-rotating spin cycloid. Our findings confirm the significance of this interaction for magnets in reduced dimensions. Chirality in nanoscale magnets may play a crucial role in spintronic devices, where the spin rather than the charge of an electron is used for data transmission and manipulation. For instance, a spin-polarized current flowing through chiral magnetic structures will exert a spin-torque on the magnetic structure, causing a variety of excitations or manipulations of the magnetization and giving rise to microwave emission, magnetization switching, or magnetic motors.     

Visualizing single-molecule diffusion in mesoporous materials

Periodic mesoporous materials formed through the cooperative self-assembly of surfactants and framework building blocks can assume a variety of structures, and their widely tuneable properties make them attractive hosts for numerous applications. Because the molecular movement in the pore system is the most important and defining characteristic of porous materials, it is of interest to learn about this behaviour as a function of local structure. Generally, individual fluorescent dye molecules can be used as molecular beacons with which to explore the structure of--and the dynamics within--these porous hosts, and single-molecule fluorescence techniques provide detailed insights into the dynamics of various processes, ranging from biology to heterogeneous catalysis. However, optical microscopy methods cannot directly image the mesoporous structure of the host system accommodating the diffusing molecules, whereas transmission electron microscopy provides detailed images of the porous structure, but no dynamic information. It has therefore not been possible to 'see' how molecules diffuse in a real nanoscale pore structure. Here we present a combination of electron microscopic mapping and optical single-molecule tracking experiments to reveal how a single luminescent dye molecule travels through linear or strongly curved sections of a mesoporous channel system. In our approach we directly correlate porous structures detected by transmission electron microscopy with the diffusion dynamics of single molecules detected by optical microscopy. This opens up new ways of understanding the interactions of host and guest.     

Metagenomic and functional analysis of hindgut microbiota of a wood-feeding higher termite

From the standpoints of both basic research and biotechnology, there is considerable interest in reaching a clearer understanding of the diversity of biological mechanisms employed during lignocellulose degradation. Globally, termites are an extremely successful group of wood-degrading organisms and are therefore important both for their roles in carbon turnover in the environment and as potential sources of biochemical catalysts for efforts aimed at converting wood into biofuels. Only recently have data supported any direct role for the symbiotic bacteria in the gut of the termite in cellulose and xylan hydrolysis. Here we use a metagenomic analysis of the bacterial community resident in the hindgut paunch of a wood-feeding 'higher' Nasutitermes species (which do not contain cellulose-fermenting protozoa) to show the presence of a large, diverse set of bacterial genes for cellulose and xylan hydrolysis. Many of these genes were expressed in vivo or had cellulase activity in vitro, and further analyses implicate spirochete and fibrobacter species in gut lignocellulose degradation. New insights into other important symbiotic functions including H2 metabolism, CO2-reductive acetogenesis and N2 fixation are also provided by this first system-wide gene analysis of a microbial community specialized towards plant lignocellulose degradation. Our results underscore how complex even a 1-microl environment can be.     

Lanthanide contraction and magnetism in the heavy rare earth elements

The heavy rare earth elements crystallize into hexagonally close packed (h.c.p.) structures and share a common outer electronic configuration, differing only in the number of 4f electrons they have. These chemically inert 4f electrons set up localized magnetic moments, which are coupled via an indirect exchange interaction involving the conduction electrons. This leads to the formation of a wide variety of magnetic structures, the periodicities of which are often incommensurate with the underlying crystal lattice. Such incommensurate ordering is associated with a 'webbed' topology of the momentum space surface separating the occupied and unoccupied electron states (the Fermi surface). The shape of this surface-and hence the magnetic structure-for the heavy rare earth elements is known to depend on the ratio of the interplanar spacing c and the interatomic, intraplanar spacing a of the h.c.p. lattice. A theoretical understanding of this problem is, however, far from complete. Here, using gadolinium as a prototype for all the heavy rare earth elements, we generate a unified magnetic phase diagram, which unequivocally links the magnetic structures of the heavy rare earths to their lattice parameters. In addition to verifying the importance of the c/a ratio, we find that the atomic unit cell volume plays a separate, distinct role in determining the magnetic properties: we show that the trend from ferromagnetism to incommensurate ordering as atomic number increases is connected to the concomitant decrease in unit cell volume. This volume decrease occurs because of the so-called lanthanide contraction, where the addition of electrons to the poorly shielding 4f orbitals leads to an increase in effective nuclear charge and, correspondingly, a decrease in ionic radii.