A six-lobed membrane spanning cellulose synthesis complex (CSC) containing multiple cellulose synthase (CESA) glycosyltransferases mediates cellulose microfibril formation. The number of CESAs in the ...CSC has been debated for decades in light of changing estimates of the diameter of the smallest microfibril formed from the β-1,4 glucan chains synthesized by one CSC. We obtained more direct evidence through generating improved transmission electron microscopy (TEM) images and image averages of the rosette-type CSC, revealing the frequent triangularity and average cross-sectional area in the plasma membrane of its individual lobes. Trimeric oligomers of two alternative CESA computational models corresponded well with individual lobe geometry. A six-fold assembly of the trimeric computational oligomer had the lowest potential energy per monomer and was consistent with rosette CSC morphology. Negative stain TEM and image averaging showed the triangularity of a recombinant CESA cytosolic domain, consistent with previous modeling of its trimeric nature from small angle scattering (SAXS) data. Six trimeric SAXS models nearly filled the space below an average FF-TEM image of the rosette CSC. In summary, the multifaceted data support a rosette CSC with 18 CESAs that mediates the synthesis of a fundamental microfibril composed of 18 glucan chains.
Glutathione (GSH) plays diverse roles in the physiological processes, stress defense, growth, and development of plants. This study investigated the effects of exogenous GSH on the biochemical ...responses of reactive oxygen species and antioxidant levels in rice (
Oryza sativa
L. cv. Dasan) seedlings under arsenic (As) stress. As treatment inhibited growth; increased the level of superoxide, hydrogen peroxide, and malondialdehyde; and enhanced the uptake of As by the roots and shoots in hydroponically grown 14-day-old seedlings. Furthermore, it reduced GSH content and GSH redox ratios, which have been correlated with the decrease in ascorbate (AsA) redox state. Whereas the exogenous application of GSH in As-treated seedlings reduced As-induced oxidative stress, improved antioxidant defense systems by maintaining antioxidant and/or redox enzyme homeostasis, and increased the AsA and GSH contents, the GSH application also increased the As translocation from the roots to the shoots. These results indicated that the increase in GSH redox state can be linked to an increase in the AsA redox ratio
via
the induction of the AsA–GSH cycle. Therefore, the results suggest that exogenous GSH application should be a promising approach to enhance As stress resistance in rice plants.
We propose a method of manipulating the coercivity of anisotropic hydrogenation-disproportionation-desorption-recombination (HDDR) powders to fabricate high-remanence and fine-grained Nd-Fe-B magnets ...using only hot-pressing without a subsequent hot-deformation process. By reducing the Nd content of anisotropic HDDR precursors such that their coercivity (H
) is lowered, the c-axis of each HDDR particle is well-aligned parallel to the direction of the applied magnetic field during the magnetic alignment step. This is because the magnetic repulsive force between adjacent particles, determined by their remanent magnetization, decreases as a result of the low coercivity of each particle. Therefore, after hot-pressing the low-H
HDDR powders, a significantly higher remanence (11.2 kG) is achieved in the bulk than that achieved by hot-pressing the high-H
HDDR powders (8.2 kG). It is clearly confirmed by the large-scale electron backscatter diffraction (EBSD) analysis that the alignment of the c-axis of each anisotropic HDDR particle in the bulk is improved when low-H
HDDR powders are used to fabricate hot-pressed magnets. This coercivity manipulation of HDDR powders can be a helpful method to expand the use of HDDR powders in fabricating anisotropic Nd-Fe-B bulk magnets.
The role of ascorbate (AsA) in antioxidant defense system-associated resistance to cadmium (Cd) in oilseed rape plants has not yet been clearly demonstrated. The present study investigated the ...critical role of exogenous AsA on the physiological and biochemical responses of reactive oxygen species (ROS) and antioxidant scavenging defense systems in oilseed rape (
L. cv. Tammi) seedlings exposed to Cd. Cd (10 μM) treatment led to significant reductions in plant growth; increases in the levels of superoxide anion radical, hydrogen peroxide, and malondialdehyde; and increases in Cd uptake and accumulation by the roots and shoots in hydroponically grown 10-day-old seedlings. Moreover, it reduced AsA content and AsA redox ratios, which have been correlated with reductions in glutathione (GSH) and/or nicotinamide adenine dinucleotide phosphate (NADPH) redox status. However, exogenously applying AsA to Cd-exposed seedlings decreased Cd-induced ROS, improved antioxidant defense systems by increasing AsA, GSH, and NADPH contents, and increased Cd uptake and accumulation in both roots and shoots of the plants. These results provided evidence that the enhancement in AsA redox status can be linked to an increase in the GSH and/or NADPH redox ratios through the induction of the AsA-GSH-NADPH cycle. Thus, these results suggest that exogenous AsA application to oilseed rape seedlings under Cd stress might alleviate the overall Cd toxicity by regulating the homeostasis of the AsA-GSH-NADPH cycle, which reestablishes the steady-state cellular redox status.
Abstract
Early life stress (ELS) causes long-lasting changes in gene expression through epigenetic mechanisms. However, little is known about the effects of ELS in adulthood, specifically across ...different age groups. In this study, the epigenetic modifications of p11 expression in adult mice subjected to ELS were investigated in different stages of adulthood. Pups experienced maternal separation (MS) for 3 h daily from postnatal day 1 to 21. At young and middle adulthood, behavioral test, hippocampal p11 expression levels, and levels of histone acetylation and methylation and DNA methylation at the hippocampal p11 promoter were measured. Middle-aged, but not young adult, MS mice exhibited increased immobility time in the forced swimming test. Concurrent with reduced hippocampal p11 levels, mice in both age groups showed a decrease in histone acetylation (AcH3) and permissive histone methylation (H3K4me3) at the p11 promoter, as well as an increase in repressive histone methylation (H3K27me3). Moreover, our results showed that the expression, AcH3 and H3Kme3 levels of p11 gene in response to MS were reduced with age. DNA methylation analysis of the p11 promoter revealed increased CpG methylation in middle-aged MS mice only. The results highlight the age-dependent deleterious effects of ELS on the epigenetic modifications of p11 transcription.
Early life stress (ELS) exerts long-lasting epigenetic influences on the brain and makes an individual susceptible to later depression. It is poorly understood whether ELS and subsequent adult ...chronic stress modulate epigenetic mechanisms. We examined the epigenetic mechanisms of the BDNF gene in the hippocampus, which may underlie stress vulnerability to postnatal maternal separation (MS) and adult restraint stress (RS). Rat pups were separated from their dams (3 h/day from P1–P21). When the pups reached adulthood (8 weeks old), we introduced RS (2 h/day for 3 weeks) followed by escitalopram treatment. We showed that both the MS and RS groups expressed reduced levels of total and exon IV BDNF mRNA. Furthermore, RS potentiated MS-induced decreases in these expression levels. Similarly, both the MS and RS groups showed decreased levels of acetylated histone H3 and H4 at BDNF promoter IV, and RS exacerbated MS-induced decreases of H3 and H4 acetylation. Both the MS and RS groups had increased MeCP2 levels at BDNF promoter IV, as well as increased HDAC5 mRNA, and the combination of MS and RS exerted a greater effect on these parameters than did RS alone. In the forced swimming test, the immobility time of the MS + RS group was significantly higher than that of the RS group. Additionally, chronic escitalopram treatment recovered these alterations. Our results suggest that postnatal MS and subsequent adult RS modulate epigenetic changes in the BDNF gene, and that these changes may be related to behavioral phenotype. These epigenetic mechanisms are involved in escitalopram action.
•Maternal separation (MS) and adult restraint stress (RS) reduced BDNF expression.•Both MS and RS modulated epigenetic mechanisms at BDNF promoter IV.•Both MS and RS increased the levels of HDAC5 mRNA.•MS and subsequent RS (MS + RS) are able to modulate epigenetic changes of BDNF.•These effects may be related to depression-like behavior.
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Efficient heat transport along through-plane direction is one of the primary requisites for thermal interface materials (TIMs) to relieve heat accumulation at the interface between ...chip and heat sinks. We report enhanced thermal conduction of Al2O3-based polymer composites by surface wetting and texturing of thermally conductive hexagonal boron nitride (h-BN) nanoplatelets with large anisotropy (diameter <500nm, thickness <30nm) in morphology and physical properties. The thermally conductive polymer composites are prepared with hybrid fillers of Al2O3 macrobeads and surface modified h-BN nanoplatelets. Here, the clustering or assembly of h-BN nanoplatelets is analyzed based on depletion interaction of colloidal particles. In addition, further addition of minimal amount of SiO2 nanoparticles shows a drastic improvement of thermal transport properties, which is attributed to the depletion interaction between nanoplatelets mediated by spherical nanoparticles. Here, the benefits of surface wetting for thermal management composite materials are illustrated.
A simple, scalable spray drying method was developed for high-yield epsilon iron oxide (ε-Fe 2 O 3 ) synthesis. The ε-Fe 2 O 3 particle size can be tailored by varying the annealing temperature and ...molar ratio of Fe/Si, producing a high-purity ε-phase. This strategy also enables ferromagnetic resonance tuning, making it potentially usable in millimeter-wave absorbers.
•Physical exercise has an antidepressant-like effect.•Immobilization stress decreases the levels of BDNF and p-Trk, Akt, GSK-3β, and mTOR.•This stress decreases the expression of synaptic ...proteins.•Treadmill exercise increases these proteins levels with or without stress.•Exercise may increase synaptic protein levels via activation of PI3K/mTOR signaling.
A growing body of evidence suggests that exercise enhances hippocampal plasticity and function through BDNF up-regulation, which is potentiated by antidepressant treatment. However, little is known about the molecular mechanisms mediating the effect of exercise. The present study investigated the effect of treadmill exercise on PI3K/Akt signaling, which mediates synaptic plasticity in the hippocampus of stressed rats. Rats were subjected to immobilization stress 2h/day for 7 days. The rats were run on the treadmill at a speed of 15m/min, 30min/day, for 5 days. Western blotting was used to assess changes in the levels of phospho-tyr490-Trk receptor, phospho-ser473-Akt, phospho-ser9-GSK-3β, phospho-ser2448- mTOR, and phosphor-thr389-p70S6K, and in BDNF and various synaptic proteins. Immobilization stress significantly decreased BDNF expression and phosphorylation of Trk receptor, Akt, GSK-3β, mTOR, and p70S6K in the hippocampus of rats; furthermore, synaptophysin, PSD-95, neuroligin 1, and β-neurexin were decreased. Treadmill exercise significantly attenuated the decreased expression of these proteins. Moreover, exercise significantly increased PI3K/Akt signaling in the absence of immobilization stress. These results suggest that treadmill exercise reverses stress-induced changes in the rat hippocampus via an increase in PI3K/Akt signaling and may induce a functional reconnection of hippocampal synapses that mediate antidepressant actions.
Halloysite nanotube (HNT)-based supramolecular complexes are synthesized and evaluated with respect to their cytotoxicity and effects on cellular structures. As HNTs are water-insoluble, DNA is ...applied for wrapping the surface of HNTs to enhance their water-dispersibility. To investigate the potential of DNA-wrapped HNTs (HD) as a promising drug delivery carrier, doxorubicin (DOX) is introduced as a model anticancer agent and loaded onto HD. The DOX-loaded, DNA-wrapped HNTs (HDD) show sustained DOX release over two weeks without initial burst of DOX indicating delayed DOX release inside cells. In addition, effects of DNA-wrapped HNTs (HD) or HDD on the cytoskeleton organization of A549 cells are studied by visualizing the distribution of F-actin filaments using confocal laser scanning microscopy, and cellular morphological changes are observed by scanning electron microscopy and scanning ion conductance microscopy.
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