Micro-patterning of biomolecules on polymer substrates.

UV−excimer laser photoablation was used, in combination with surface blocking techniques, to pattern proteins on the surfaces of polyimide and poly(ethylene terephthalate). This technique involves physical adsorption of avidin through laser-defined openings in low-temperature laminates or adsorbed protein blocking layers. Visualization of biomolecular patterns were monitored using avidin and fluorescein-labeled biotin as a model receptor−ligand couple. Adsorbed proteins could be shown to bind to UV-laser-treated polymer surfaces up to three times higher than on commercially available polymers. UV-laser photoablation was also used for the generation of three-dimensional structure, which leads to the possibility of biomolecule patterning within polymer-based microanalytical systems. The simplicity and easy handling of the described technique facilitate its application in microdiagnostic devices.

The adequacy of artificial oviposition substrates for laboratory rearing of Piezodorus guildinii (Westwood) (Heteroptera, Pentatomidae)

Studies in the laboratory tested the suitability of synthetic wool string, cotton string, cheesecloth, and commercial cotton ball as artificial oviposition substrates for the small green stink bug, Piezodorus guildinii (Westwood) (Heteroptera, Pentatomidae). In confined cages, 54% of total egg masses was laid on synthetic wool string, 31% on cotton string, and only 15% on cheesecloth. In an additional test, the best substrate selected, synthetic wool string, received 92% of egg masses compared to 8% on the commonly used substrate, cotton ball. Synthetic wool string received the most egg masses of any size, in particular those in the range 11-20 eggs/mass. Because the eggs of P. guildinii are laid in two parallel double rows, the egg masses fit the wool string perfectly.

Use of artificial substrates of different colors for oviposition by the brown stink bug Euschistus heros (Hemiptera, Pentatomidae)

Aiming to contribute to a rearing methodology for the brown stink bug, Euschistus heros, in the laboratory, we evaluated oviposition on artificial substrates of different colors. During six days, oviposition was evaluated daily, by counting the total number of eggs, number of clutches, and eggs/clutch. Females laid 12,463 eggs, in 1,677 clutches, resulting in an average of 7.28 ± 0.44 eggs/clutch. Black, brown, and green felt had the most eggs and clutches. The results demonstrated that many colors are suitable as oviposition substrate for E. heros, providing information for the mass rearing of this insect.

Eficiencia y comportamiento de las redes de arrastre pelágicas. Crucero BICs José Olaya Balandra y SNP-2 0001-02

El crucero se efectuó del 18 de enro al 29 de febrero del 2000, mostró que las redes de arrastre pelágicas tuvieron una buena eficiencia y comportamiento en los 299 lances de comprobación.

Knock, knock, knocking on muscle doors. Visions on the transport of substrates across the plasma membrane in muscle.

Muscle is a major player in metabolism. It uses large amounts of glucose in the absorptive state and changes in muscle insulin-stimulated glucose uptake alter whole-body glucose disposal. Lipid substrates such as fatty acids or ketone bodies are preferentially used by muscle in certain physiological conditions. Muscle is also the main reservoir of amino acids and protein. The activity of many different plasma membrane transporters such as glucose carriers, carnitine, creatine or amino acid transporters maintain muscle metabolism by taking up or releasing substrates or metabolites across the cell surface. The goal of this review is the molecular characterization of muscle membrane transporter proteins and the analysis of their regulatory roles.

Screen printed La2/3Sr1/3MnO3 thick films on alumina substrates

We report here on the preparation of La2/3Sr1/3MnO3 magnetoresistive thick films on polycrystalline Al2O3 substrates by using the screen printing technique. It is shown that films can be obtained using high temperature sintering. While there is a reacted layer, this improves adhesion and is not too troublesome if the films are made thick enough. It is shown that PbO-B2O3-SiO2 glass additives allow sintering at lower temperatures and can be used to improve the mechanical stress of the films. However, it is found that glass concentrations large enough to significantly improve the film adherence result in a weak low field magnetoresistance probably because grains are coated with high resistivity material. Strategies to overcome these difficulties are discussed.

Cationic Diffusion in La2/3Ca1/3MnO3 Thin Films Grown on LaAlO3 (001) Substrates.

Microstructural features of La2/3Ca1/3MnO3 layers of various thicknesses grown on top of 001 LaAlO3 substrates are studied by using transmission electron microscopy and electron energy loss spectroscopy. Films are of high microstructural quality but exhibit some structural relaxation and mosaicity both when increasing thickness or after annealing processes. The existence of a cationic segregation process of La atoms toward free surface has been detected, as well as a Mn oxidation state variation through layer thickness. La diffusion would lead to a Mn valence change and, in turn, to reduced magnetization.

Raman scattering of InSb quantum dots grown on InP substrates

In this paper we present the Raman scattering of self-assembled InSb dots grown on (001) oriented InP substrates. The samples were grown by pulsed molecular beam epitaxy mode. Two types of samples have been investigated. In one type the InSb dots were capped with 200 monolayers of InP; in the other type no capping was deposited after the InSb dot formation. We observe two peaks in the Raman spectra of the uncapped dot, while only one peak is observed in the Raman spectra of the capped dots. In the case of the uncapped dots the peaks are attributed to LO-like and TO-like vibration of completely relaxed InSb dots, in agreement with high resolution transmission electron microscopy photographs. The Raman spectra of the capped dot suggest a different strain state in the dot due to the capping layer.

From nonwetting to prewetting: The asymptotic behavior of 4He drops on alkali substrates

We investigate the spreading of 4He droplets on alkali-metal surfaces at zero temperature, within the frame of finite range density-functional theory. The equilibrium configurations of several 4HeN clusters and their asymptotic trend with increasing particle number N, which can be traced to the wetting behavior of the quantum fluid, are examined for nanoscopic droplets. We discuss the size effects inferring that the asymptotic properties of large droplets correspond to those of the prewetting film.

Freezing of 4He and its liquid-solid interface from density functional theory

We show that, at high densities, fully variational solutions of solidlike types can be obtained from a density functional formalism originally designed for liquid 4He . Motivated by this finding, we propose an extension of the method that accurately describes the solid phase and the freezing transition of liquid 4He at zero temperature. The density profile of the interface between liquid and the (0001) surface of the 4He crystal is also investigated, and its surface energy evaluated. The interfacial tension is found to be in semiquantitative agreement with experiments and with other microscopic calculations. This opens the possibility to use unbiased density functional (DF) methods to study highly nonhomogeneous systems, like 4He interacting with strongly attractive impurities and/or substrates, or the nucleation of the solid phase in the metastable liquid.

Dynamics of driven three-dimensional thin films: from hdrophilic to superhydrophobic substrates

We study the forced displacement of a thin film of fluid in contact with vertical and inclined substrates of different wetting properties, that range from hydrophilic to hydrophobic, using the lattice-Boltzmann method. We study the stability and pattern formation of the contact line in the hydrophilic and superhydrophobic regimes, which correspond to wedge-shaped and nose-shaped fronts, respectively. We find that contact lines are considerably more stable for hydrophilic substrates and small inclination angles. The qualitative behavior of the front in the linear regime remains independent of the wetting properties of the substrate as a single dispersion relation describes the stability of both wedges and noses. Nonlinear patterns show a clear dependence on wetting properties and substrate inclination angle. The effect is quantified in terms of the pattern growth rate, which vanishes for the sawtooth pattern and is finite for the finger pattern. Sawtooth shaped patterns are observed for hydrophilic substrates and low inclination angles, while finger-shaped patterns arise for hydrophobic substrates and large inclination angles. Finger dynamics show a transient in which neighboring fingers interact, followed by a steady state where each finger grows independently.

Dynamics of driven three-dimensional thin films: from hdrophilic to superhydrophobic substrates

We study the forced displacement of a thin film of fluid in contact with vertical and inclined substrates of different wetting properties, that range from hydrophilic to hydrophobic, using the lattice-Boltzmann method. We study the stability and pattern formation of the contact line in the hydrophilic and superhydrophobic regimes, which correspond to wedge-shaped and nose-shaped fronts, respectively. We find that contact lines are considerably more stable for hydrophilic substrates and small inclination angles. The qualitative behavior of the front in the linear regime remains independent of the wetting properties of the substrate as a single dispersion relation describes the stability of both wedges and noses. Nonlinear patterns show a clear dependence on wetting properties and substrate inclination angle. The effect is quantified in terms of the pattern growth rate, which vanishes for the sawtooth pattern and is finite for the finger pattern. Sawtooth shaped patterns are observed for hydrophilic substrates and low inclination angles, while finger-shaped patterns arise for hydrophobic substrates and large inclination angles. Finger dynamics show a transient in which neighboring fingers interact, followed by a steady state where each finger grows independently.

Food for thought: the importance of glucose and other energy substrates for sustaining brain function under varying levels of activity.

The brain requires a constant and substantial energy supply to maintain its main functions. For decades, it was assumed that glucose was the major if not the only significant source of energy for neurons. This view was supported by the expression of specific facilitative glucose transporters on cerebral blood vessels, as well as neurons. Despite the fact that glucose remains a key energetic substrate for the brain, growing evidence suggests a different scenario. Thus astrocytes, a major type of glial cells that express their own glucose transporter, play a critical role in coupling synaptic activity with glucose utilization. It was shown that glutamatergic activity triggers an enhancement of aerobic glycolysis in this cell type. As a result, lactate is provided to neurons as an additional energy substrate. Indeed, lactate has proven to be a preferential energy substrate for neurons under various conditions. A family of proton-linked carriers known as monocarboxylate transporters has been described and specific members have been found to be expressed by endothelial cells, astrocytes and neurons. Moreover, these transporters are subject to fine regulation of their expression levels and localization, notably in neurons, which suggests that lactate supply could be adjusted as a function of their level of activity. Considering the importance of energetics in the aetiology of several neurodegenerative diseases, a better understanding of its cellular and molecular underpinnings might have important implications for the future development of neuroprotective strategies.

Biophysical characterization of two different stable misfolded monomeric polypeptides that are chaperone-amenable substrates.

Misfolded polypeptide monomers may be regarded as the initial species of many protein aggregation pathways, which could accordingly serve as primary targets for molecular chaperones. It is therefore of paramount importance to study the cellular mechanisms that can prevent misfolded monomers from entering the toxic aggregation pathway and moreover rehabilitate them into active proteins. Here, we produced two stable misfolded monomers of luciferase and rhodanese, which we found to be differently processed by the Hsp70 chaperone machinery and whose conformational properties were investigated by biophysical approaches. In spite of their monomeric nature, they displayed enhanced thioflavin T fluorescence, non-native β-sheets, and tertiary structures with surface-accessible hydrophobic patches, but differed in their conformational stability and aggregation propensity. Interestingly, minor structural differences between the two misfolded species could account for their markedly different behavior in chaperone-mediated unfolding/refolding assays. Indeed, only a single DnaK molecule was sufficient to unfold by direct clamping a misfolded luciferase monomer, while, by contrast, several DnaK molecules were necessary to unfold the more resistant misfolded rhodanese monomer by a combination of direct clamping and cooperative entropic pulling.

Review: Contact sport-related chronic traumatic encephalopathy in the elderly: clinical expression and structural substrates.

A. Costanza, K. Weber, S. Gandy, C. Bouras, P. R. Hof, P. Giannakopoulos and A. Canuto (2011) Neuropathology and Applied Neurobiology37, 570-584 Contact sport-related chronic traumatic encephalopathy in the elderly: clinical expression and structural substrates Professional boxers and other contact sport athletes are exposed to repetitive brain trauma that may affect motor functions, cognitive performance, emotional regulation and social awareness. The term of chronic traumatic encephalopathy (CTE) was recently introduced to regroup a wide spectrum of symptoms such as cerebellar, pyramidal and extrapyramidal syndromes, impairments in orientation, memory, language, attention, information processing and frontal executive functions, as well as personality changes and behavioural and psychiatric symptoms. Magnetic resonance imaging usually reveals hippocampal and vermis atrophy, a cavum septum pellucidum, signs of diffuse axonal injury, pituitary gland atrophy, dilated perivascular spaces and periventricular white matter disease. Given the partial overlapping of the clinical expression, epidemiology and pathogenesis of CTE and Alzheimer's disease (AD), as well as the close association between traumatic brain injuries (TBIs) and neurofibrillary tangle formation, a mixed pathology promoted by pathogenetic cascades resulting in either CTE or AD has been postulated. Molecular studies suggested that TBIs increase the neurotoxicity of the TAR DNA-binding protein 43 (TDP-43) that is a key pathological marker of ubiquitin-positive forms of frontotemporal dementia (FTLD-TDP) associated or not with motor neurone disease/amyotrophic lateral sclerosis (ALS). Similar patterns of immunoreactivity for TDP-43 in CTE, FTLD-TDP and ALS as well as epidemiological correlations support the presence of common pathogenetic mechanisms. The present review provides a critical update of the evolution of the concept of CTE with reference to its neuropathological definition together with an in-depth discussion of the differential diagnosis between this entity, AD and frontotemporal dementia.