Short-term hyperhomocysteinemia-induced oxidative stress activates retinal glial cells and increases vascular endothelial growth factor expression in rat retina

Hyperhomocysteinemia is associated with an increase in the incidence of vascular diseases, including retinal vascular diseases. We examined the effects of high plasma levels of homocysteine on retinal glial cells and vascular endothelial growth factor (VEGF) expression. Male Sprague-Dawley rats were fed either a 3.0 g/kg homocystine diet or a control diet for 2 week. The homocystine-diet group had higher plasma levels of homocysteine and thiobarbituric acid reactive substances (TBARSs) and lower plasma levels of folate, retinol, alpha-tocopherol, and retinal expression of CuZn superoxide dismutase (SOD) than the controls. The rats fed the homocystine-diet showed an increase in vimentin, glial fibrillary acidic protein (GFAP), and VEGF immunoreactivity in the retina as compared to the controls. The increase in vimentin immunoreactivity in the hyperhomocysteinemic rats was correlated with changes in GFAP immunoreactivity in astrocytes within the ganglion cell layer. We found for the first time that short-term hyperhomocysteinemia-induced oxidative stress activates retinal glial cells and increases VEGF expression in the retina.     

Robust Pitch on Silicon Nanolayer–Embedded Graphite for Suppressing Undesirable Volume Expansion

A significant volume expansion exhibited by high‐capacity active materials upon lithiation has hindered their application as Li‐ion battery anode materials. Although tremendous progress has been made in the development of coating methods that improve the stability of high‐capacity active materials, suitable coating sources that are both strong and economical to use are yet to be discovered. Pitch is reported here as a promising coating source for high‐capacity anodes owing to the high mechanical strength and low‐cost process. Using in situ transmission electron microscopy, it is found that pitch can withstand the severe volume expansion that occurs upon Si lithiation owing to its high mechanical strength, originating from the long‐range graphitic ordering. Notably, pitch‐coated silicon nanolayer–embedded graphite (SG) exhibits superior capacity retention (81.9%) compared to that of acetylene‐coated SG (66%) over 200 cycles in a full‐cell by effectively mitigating volume expansion, even under industrial electrode density conditions (1.6 g cc^?1). Thus, this work presents new possibilities for the development of high‐capacity anodes for industrial implementation.     

High‐Output Triboelectric Nanogenerator Based on Dual Inductive and Resonance Effects‐Controlled Highly Transparent Polyimide for Self‐Powered Sensor Network Systems

High‐output triboelectric nanogenerators (TENGs) are demonstrated based on polyimide (PI)‐based polymers by introducing functionalities (e.g., electron‐withdrawing and electron‐donating groups) into the backbone. The TENG based on 6FDA‐APS PI, possessing the most negative electrostatic potential and the low‐lying lowest unoccupied molecular orbital level, produces the highest effective charge density of about 860 µC m^?2 in practical working conditions with the ion injection process. This may be ascribed to the excellent charge‐retention characteristics as well as the enhanced charge transfer capability, which increases the output power by 7 times compared to the commercially available Kapton film‐based TENG. Finally, a 6FDA‐APS‐driven sensor network system is demonstrated, providing the identity of three gases (H₂, CO, and NO₂) by illuminating the light‐emitting diodes within several seconds.     

Computation of the electrophoretic mobility of proteins.

A scheme is presented for computing the electrophoretic mobility of proteins in free solution, accounting for the details of the protein shape and charge distribution. The method of Teubner is implemented using a boundary integral formulation within which the velocity distribution, the equilibrium electrical potential around the molecule, and the potential distribution due to the applied field are solved for numerically using the boundary element method. Good agreement of the numerical result is obtained for spheres with the corresponding semi-analytical specialization of Henry's analysis. For protein systems, the method is applied to lysozyme and ribonuclease A. In both cases, the predicted mobility tensors are fairly isotropic, with the resulting scalar mobilities being significantly smaller than for spheres of equal volume and net charge. Comparisons with previously published experimental results for ribonuclease show agreement to be excellent in the presence of a net charge, but poorer at the point of zero charge. The approach may be useful for evaluating approximate methods for estimating protein electrophoretic mobilities and for using electrophoretic measurements to obtain insight into charge distributions on proteins.     

A novel stress-related gene in developing pepper anthers

To study gene expression patterns and to find genes related with microspore embryogenesis during pepper (Capsicum annuum L.) anther development, mRNA expression patterns were investigated at four developmental stages distinguished according to the size of flower bud, the color of anthers, and the cytological feature of microspores. Through GeneFishing using 120 random primers, 81 genes were found to be differentially expressed as anthers develop. We directly sequenced seven of them, which were either up- or down-regulated at stage 2, since microspores at stage 2 are known to be responsive to the induction signals for microspore embryogenesis. Nucleotide sequence analysis of the isolated differentially expressed genes (DEGs) and the comparison of these sequences with the GenBank data indicate that DEG13 is a novel gene, which is highly homologous to a stress-related gene of potato, POACT88 (≈91%) and to alcohol dehydrogenase gene of Arabidopsis (≈70%), whose expression is also tightly related to stresses. In vitro data also showed that DEG13 was more abundantly expressed in heat-treated microspores than in untreated microspores. Here, we report developmental stage-specific gene expression patterns during anther development and a novel stress-related gene, DEG13, which may be involved in microspore embryogenesis in response to heat treatment.     

Interaction models of substrate peptides and β-secretase studied by NMR spectroscopy and molecular dynamics simulation

The formation of β-amyloid peptide (Aβ) is initiated from cleavage of amyloid precursor protein (APP) by a family of protease, α-, β-, and γ-secretase. Sub W, a substrate peptide, consists of 10 amino acids, which are adjacent to the β-cleavage site of wild-type APP, and Sub M is Swedish mutant with double mutations on the left side of the β-cleavage site of APP. Sub W is a normal product of the metabolism of APP in the secretary pathway. Sub M is known to increase the efficiency of β-secretase activity, resulting in a more specific binding model compared to Sub W. Three-dimensional structures of Sub W and Sub M were studied by CD and NMR spectroscopy in water solution. On the basis of these structures, interaction models of β-secretase and substrate peptides were determined by molecular dynamics simulation. Four hydrogen bonds and one water-mediated interaction were formed in the docking models. In particular, the hydrogen bonding network of Sub M-BACE formed spread over the broad region of the active site of β-secretase (P5-P3′), and the side chain of P2-Asn formed a hydrogen bond specifically with the side chain of Arg235. These are more favorable to the cleavage of Sub M by β-secretase than Sub W. The two substrate peptides showed different tendency to bind to β-secretase and this information may useful for drug development to treat and prevent Alzheimer’s disease.     

Coupling of Pressure-Induced Structural Shifts to Spectral Changes in a Yellow Fluorescent Protein

X-ray diffraction analysis of pressure-induced structural changes in the Aequorea yellow fluorescent protein Citrine reveals the structural basis for the continuous fluorescence peak shift from yellow to green that is observed on pressurization. This fluorescence peak shift is caused by a reorientation of the two elements of the Citrine chromophore. This study describes the structural linkages in Citrine that are responsible for the local reorientation of the chromophore. The deformation of the Citrine chromophore is actuated by the differential motion of two clusters of atoms that compose the β-barrel scaffold of the molecule, resulting in a slight bending of the β-barrel. The high-pressure structures also show a perturbation of the hydrogen bonding network that stabilizes the excited state of the Citrine chromophore. The perturbation of this network is implicated in the reduction of fluorescence intensity of Citrine. The blue-shift of the Citrine fluorescence spectrum resulting from the bending of the β-barrel provides structural insight into the transient blue-shifting of isolated yellow fluorescent protein molecules under ambient conditions and suggests mechanisms to alter the time-dependent behavior of Citrine under ambient conditions.