Stiffness gradients in vascular bundles of the palm Washingtonia robusta

Palms can grow at sites exposed to high winds experiencing large dynamic wind and gust loads. Their stems represent a system of stiff fibrous elements embedded in the soft parenchymatous tissue. The proper design of the interface of the stiffening elements and the parenchyma is crucial for the functioning of the stem. The strategy of the palm to compromise between stiff fibre caps and the soft parenchymatous tissue may serve as a model system for avoiding stress discontinuities in inhomogeneous and anisotropic fibre-reinforced composite materials. We investigated the mechanical, structural and biochemical properties of the fibre caps of the palm Washingtonia robusta at different levels of hierarchy with high spatial resolution. A gradual decrease in stiffness across the fibre cap towards the surrounding parenchymatous tissue was observed. Structural adaptations at the tissue level were found in terms of changes in cell cross sections and cell wall thickness. At the cell wall level, gradients across the fibre cap were found in the degree of orientation of the microfibrils and in the lignin level and composition. The impact of these structural variations in the local material stiffness distribution is discussed.     

A cytomegalovirus glycoprotein re-routes MHC class I complexes to lysosomes for degradation

Mouse cytomegalovirus (MCMV) early gene expression interferes with the major histocompatibility complex class I (MHC class I) pathway of antigen presentation. Here we identify a 48 kDa type I transmembrane glycoprotein encoded by the MCMV early gene m06, which tightly binds to properly folded beta2-microglobulin (beta2m)-associated MHC class I molecules in the endoplasmic reticulum (ER). This association is mediated by the lumenal/transmembrane part of the protein. gp48-MHC class I complexes are transported out of the ER, pass the Golgi, but instead of being expressed on the cell surface, they are redirected to the endocytic route and rapidly degraded in a Lamp-1(+) compartment. As a result, m06-expressing cells are impaired in presenting antigenic peptides to CD8(+) T cells. The cytoplasmic tail of gp48 contains two di-leucine motifs. Mutation of the membrane-proximal di-leucine motif of gp48 restored surface expression of MHC class I, while mutation of the distal one had no effect. The results establish a novel viral mechanism for downregulation of MHC class I molecules by directly binding surface-destined MHC complexes and exploiting the cellular di-leucine sorting machinery for lysosomal degradation.     

Primers and polymerase chain reaction conditions for DNA barcoding teleost fish based on the mitochondrial cytochrome b and nuclear rhodopsin genes

This report describes a set of 21 polymerase chain reaction primers and amplification conditions developed to barcode practically any teleost fish species according to their mitochondrial cytochrome b and nuclear rhodopsin gene sequences. The method was successfully tested in more than 200 marine fish species comprising the main Actinopterygii family groups. When used in phylogenetic analyses, its combination of two genes with different evolutionary rates serves to identify fish at the species level. We provide a flow diagram indicating our validated polymerase chain reaction amplification conditions for barcoding and species identification applications as well as population structure or haplotyping analyses, adaptable to high‐throughput analyses.     

Tensile and compressive stresses in tracheids are induced by swelling based on geometrical constraints of the wood cell

Plants are able to pre-stress their tissues in order to actuate their organs. Here, we demonstrate with two tissue types of the secondary xylem of conifers (normal wood and compression wood of spruce (Picea abies)) that either tensile or compressive stresses can develop in the longitudinal direction during the swelling of the cell wall. This dramatic difference appears to be due mostly to differences in cell geometry and cellulose fibril orientation. A mechanical model was developed to demonstrate swelling experiments with the help of sodium iodide experiments. The reversal of longitudinal extension can be predicted, based on the orientation of the (nearly inextensible) cellulose fibrils and the shape of the cell.     

Bio-Inspired Wooden Actuators for Large Scale Applications

Implementing programmable actuation into materials and structures is a major topic in the field of smart materials. In particular the bilayer principle has been employed to develop actuators that respond to various kinds of stimuli. A multitude of small scale applications down to micrometer size have been developed, but up-scaling remains challenging due to either limitations in mechanical stiffness of the material or in the manufacturing processes. Here, we demonstrate the actuation of wooden bilayers in response to changes in relative humidity, making use of the high material stiffness and a good machinability to reach large scale actuation and application. Amplitude and response time of the actuation were measured and can be predicted and controlled by adapting the geometry and the constitution of the bilayers. Field tests in full weathering conditions revealed long-term stability of the actuation. The potential of the concept is shown by a first demonstrator. With the sensor and actuator intrinsically incorporated in the wooden bilayers, the daily change in relative humidity is exploited for an autonomous and solar powered movement of a tracker for solar modules.     

Assessing the reliability of eBURST using simulated populations with known ancestry

Background  

The program eBURST uses multilocus sequence typing data to divide bacterial populations into groups of closely related strains (clonal complexes), predicts the founding genotype of each group, and displays the patterns of recent evolutionary descent of all other strains in the group from the founder. The reliability of eBURST was evaluated using populations simulated with different levels of recombination in which the ancestry of all strains was known.     

PheMaDB: A solution for storage,retrieval, and analysis of high throughput phenotype data

Background  

OmniLog™ phenotype microarrays (PMs) have the capability to measure and compare the growth responses of biological samples upon exposure to hundreds of growth conditions such as different metabolites and antibiotics over a time course of hours to days. In order to manage the large amount of data produced from the OmniLog™ instrument, PheMaDB (Phenotype Microarray DataBase), a web-based relational database, was designed. PheMaDB enables efficient storage, retrieval and rapid analysis of the OmniLog™ PM data.     

Isolation and cross‐familial amplification of 41 microsatellites for the brook charr (Salvelinus fontinalis)

The brook charr (Salvelinus fontinalis; Osteichthyes: Salmonidae) is a phenotypically diverse fish species inhabiting much of North America. But relatively few genetic diagnostic resources are available for this fish species. We isolated 41 microsatellites from S. fontinalis polymorphic in one or more species of salmonid fish. Thirty‐seven were polymorphic in brook charr, 15 in the congener Arctic charr (Salvelinus alpinus) and 14 in the lake charr (Salvelinus namaycush). Polymorphism was also relatively high in Oncorhynchus, where 21 loci were polymorphic in rainbow trout (Oncorhynchus mykiss) and 16 in cutthroat trout (Oncorhynchus clarkii) but only seven and four microsatellite loci were polymorphic in the more distantly related lake whitefish (Coregonus clupeaformis) and Atlantic salmon (Salmo salar), respectively. One duplicated locus (Sfo228Lav) was polymorphic at both duplicates in S. fontinalis.     

Development, Optimization, and Characterization of Solid Self-Nanoemulsifying Drug Delivery Systems of Valsartan Using Porous Carriers

The present studies entail formulation development of novel solid self-nanoemulsifying drug delivery systems (S-SNEDDS) of valsartan with improved oral bioavailability, and evaluation of their in vitro and in vivo performance. Preliminary solubility studies were carried out and pseudoternary phase diagrams were constructed using blends of oil (Capmul MCM), surfactant (Labrasol), and cosurfactant (Tween 20). The SNEDDS were systematically optimized by response surface methodology employing 3^3-Box–Behnken design. The prepared SNEDDS were characterized for viscocity, refractive index, globule size, zeta potential, and TEM. Optimized liquid SNEDDS were formulated into free flowing granules by adsorption on the porous carriers like Aerosil 200, Sylysia (350, 550, and 730) and Neusilin US2, and compressed into tablets. In vitro dissolution studies of S-SNEDDS revealed 3–3.5-fold increased in dissolution rate of the drug due to enhanced solubility. In vivo pharmacodynamic studies in Wistar rats showed significant reduction in mean systolic BP by S-SNEDDS vis-à-vis oral suspension (p < 0.05) owing to the drug absorption through lymphatic pathways. Solid-state characterization of S-SNEDDS using FT-IR and powder XRD studies confirmed lack of any significant interaction of drug with lipidic excipients and porous carriers. Further, the accelerated stability studies for 6 months revealed that S-SNEDDS are found to be stable without any change in physiochemical properties. Thus, the present studies demonstrated the bioavailability enhancement potential of porous carriers based S-SNEDDS for a BCS class II drug, valsartan.KEY WORDS: BCS, bioavailability, in vitro dissolution, porous carriers, XRD