Enhanced expression of WD repeat-containing protein 35 (WDR35) stimulated by domoic acid in rat hippocampus: involvement of reactive oxygen species generation and p38 mitogen-activated protein kinase activation

Background

Domoic acid (DA) is an excitatory amino acid analogue of kainic acid (KA) that acts via activation of glutamate receptors to elicit a rapid and potent excitotoxic response, resulting in neuronal cell death. Recently, DA was shown to elicit reactive oxygen species (ROS) production and induce apoptosis accompanied by activation of p38 mitogen-activated protein kinase (MAPK) in vitro. We have reported that WDR35, a WD-repeat protein, may mediate apoptosis in several animal models. In the present study, we administered DA to rats intraperitoneally, then used liquid chromatography/ion trap tandem mass spectrometry (LC-MS/MS) to identify and quantify DA in the brains of the rats and performed histological examinations of the hippocampus. We further investigated the potential involvement of glutamate receptors, ROS, p38 MAPK, and WDR35 in DA-induced toxicity in vivo.

Results

Our results showed that intraperitoneally administered DA was present in the brain and induced neurodegenerative changes including apoptosis in the CA1 region of the hippocampus. DA also increased the expression of WDR35 mRNA and protein in a dose- and time-dependent manner in the hippocampus. In experiments using glutamate receptor antagonists, the AMPA/KA receptor antagonist NBQX significantly attenuated the DA-induced increase in WDR35 protein expression, but the NMDA receptor antagonist MK-801 did not. In addition, the radical scavenger edaravone significantly attenuated the DA-induced increase in WDR35 protein expression. Furthermore, NBQX and edaravone significantly attenuated the DA-induced increase in p38 MAPK phosphorylation.

Conclusion

In summary, our results indicated that DA activated AMPA/KA receptors and induced ROS production and p38 MAPK phosphorylation, resulting in an increase in the expression of WDR35 in vivo.     

Intergrowth microstructures of MnF2 subjected to shock compression

Intergrowth microstructures of MnF₂ subjected to shock compression at 4.4, 9.0 and 21.6 GPa were examined using transmission electron microscopy (TEM). Intergrowth microstructures consisting of rutile- and α-PbO₂-type phases were observed in samples shock-loaded to 4.4 and 9 GPa. The sample subjected to 21.6 GPa consisted of a twin structure with stacking faults, with a rutile-type but not the α-PbO₂-type phase. In the 9.0-GPa shocked sample, the phase ledge structure originating from a phase transition is directly captured by high-resolution transmission electron microscopy.     

Spin-glass in the spinel-type CuCrTiS4

It is difficult to find a typical compound to understand the spin-glass (SG). Only a few model compounds for the SG have been investigated; Fe_0.50Mn_0.50TiO₃ as a short-range interacting three-dimensional (3D) Ising SG, Dy_0.103Y_0.897Ru₂Si₂ as a long-range 3D Ising SG, and AgMn as a long-range 3D Heisenberg SG. A spinel-type compound CuCrTiS₄ will be provided in this study as a realistic candidate for a short-range interacting 3D Heisenberg SG. This CuCrTiS₄ can cause a SG phase below T _g?=?7.91?K, which is obtained by a random non-magnetic 50% substitution of Ti for Cr on B-sites in the ferromagnetic mother spinel CuCr₂S₄. The localized magnetic moment of CuCrTiS₄ comes from Cr³⁺ with S?=?3/2, where a valence state of Cu⁺Cr³⁺Ti⁴⁺S₄ ^2? is built up. Experimental data will be focused only on the static properties of dc magnetization M(T) under various magnetic fields, without any dynamical magnetic feature. The spin-glass phase transition T _g is well defined at low field, nevertheless hardly in higher fields than approximately 40 Oe. An appearance of the field dependence of M(T) of CuCrTiS₄ is similar to that of Fe_0.50Mn_0.50TiO₃ with the short-range Ising SG, and also these of AgMn and CuMn with the long-range interacting Heisenberg SGs. This general nature in M(T) seems to originate from the common mechanism under magnetic fields for all the spin-glasses.     

Three-dimensional quantification of texture heterogeneity in single-crystal aluminium subjected to equal channel angular pressing

Abstract

A three-dimensional crystal plasticity finite element method (3D CPFEM) modelling of a real equal channel angular pressing (ECAP) process for investigating the mechanical properties and texture evolutions of single-crystal aluminium has been developed for the first time. The challenge of modelling such a severe plastic deformation via 3D CPFEM is how to accurately predict the deformation mechanism under the complicated contact conditions between a billet and a die. The validation by comparison with experimental observations demonstrates that the developed 3D CPFEM ECAP model is able to precisely capture the deformation characteristics at the microscale. Furthermore, this research clarified the previously remaining disputes such as the microstructural formation mechanism in the deformed area and the deformation nature in the plastic deformation zone. It is also the first time to extensively discuss the orientation-dependent deformation feature of the ECAP-processed billets, including morphology, lattice rotation angle and grain refinement.     

Complex Formation of Homoionic Montmorillonites with Propylene Carbonate and Osmotic Swelling in Aqueous Electrolyte Solutions

Abstract

Homoionic montmorillonites saturated with several kinds of cations can form complexes with propylene carbonate (PC) by intercalation. The PC molecules interact with the interlayer cations by way of H₂O molecules between the silicate layers. The PC-montmorillonite complexes exhibit osmotic swelling even in aqueous electrolyte solutions. This is interpreted in terms of the formation of thick electric double-layers consisting of PC and H₂O between the silicate layers. Although the PC molecules are gradually hydrolyzed to propylene glycol between the layers, the hydrolyzed complex also shows a similar swelling power in aqueous electrolyte solutions.     

NEW CLASSIFICATION OF CHEVRONS IN ELECTROCONVECTION IN HOMEOTROPICALLY-ALIGNED NEMATICS

Abstract

Two types of chevrons have been found in the conduction regime, as well as the conventional chevrons in the dielectric regime in homeotropically-aligned nematics. These two are named the defect-mediated chevron (DMC) and the defect-free chevron (DFC) by their structure changes. Two different bifurcation sequences are found with increasing the applied voltage, such as Fréedericksz transition → normal rolls → abnormal rolls → defect chaos → DMC for low frequencies and Fréedericksz transition → prewavy pattern → DFC for high frequencies. Moreover, the double periodicity of the chevrons (i.e., the short wavelength λ₁ of the striated rolls and the long wavelength λ₂ of the chevron bands) shows quite specific frequency dependence.     

Molecular Organization of Porphyrin-Metal Complexes

Abstract

Tetraethyltetramethylporphyrin substituted at two facing meso positions by N-methylimidazolyl groupings and its metal complexes were prepared. The absorption spectra of Zn and Mg complexes showed a characteristic splitting of Soret band and red-shifts of Q-bands indicating the exciton interaction of porphyrins in a slipped cofacial arrangement, where each imidazolyl group in one metal porphyrin is coordinated to metals in the other porphyrin skeleton. Typical upfield shifts in the ¹H NMR spectra arising from such the stacking structure elucidated Zn and Mg complexes as a dimer and an oligomeric mixture, respectively. Bis(imidazolyl)substituted tetraethyltetramethyl-porphyrin was also prepared. It suggested the hydrogen bonded oligomer formation through imidazolyl-imidazolyl interactions in a columnar orientation.

Electric conductivities of films prepared from these compounds werecharacterized. In a same line with behaviors in solution, samples capable of π-stacking interaction with adjacent porphyrins via ligand-to-metal coordination or hydrogen bonding exhibited higher conductivities as well as lower activation energies for the thermal conduction. These behaviors are understood as due to the overlap of π-systems of one porphyrin with neighboring porphyrins.     

Crystal-Size Dependence of Replenishment Effect in BaFBr:Eu

Excitation spectra of photo-stimulated luminescence (PSL) in BaFBr:Eu and BaFBr:Eu ? Na crystals were studied. Replenishment of PSL at liquid helium temperature was investigated in crystals of various sizes including a commercially available X-ray storage phosphor plate (Image Plate). Although a weak replenishment effect was observed in the fine powder crystals, no replenishment effects were observed in Image Plate, while it showed strong PSL at liquid helium temperature. Results indicate that there are two types of PSL centers, one consists of spatially correlated electrons and holes and the other consists of electrons and holes trapped at isolated centers. Lack of the replenishment effect in Image Plate indicates that trapped electrons are stabilized by the surface and need thermal activation to recombine with holes which are possibly trapped at doped Eu^2?.     

Three-dimensional computation for flow-induced vibrations of an upstream circular cylinder in two tandem circular cylinders

It is well known from a lot of experimental data that fluid forces acting on two tandem circular cylinders are quite different from those acting on a single circular cylinder. Therefore, we first present numerical results for fluid forces acting on two tandem circular cylinders, which are mounted at various spacings in a smooth flow, and second we present numerical results for flow-induced vibrations of the upstream circular cylinder in the tandem arrangement. The two circular cylinders are arranged at close spacing in a flow field. The upstream circular cylinder is elastically placed by damper-spring systems and moves in both the in-line and cross-flow directions. In such models, each circular cylinder is assumed as a rigid body. On the other hand, we do not introduce a turbulent model such as the Large Eddy Simulation (LES) or Reynolds Averaged Navier-Stokes (RANS) models into the numerical scheme to compute the fluid flow. Our numerical procedure to capture the flow-induced vibration phenomena of the upstream circular cylinder is treated as a fluid-structure interaction problem in which the ideas of weak coupling is taken into consideration.