Histone H3K27 methylation modulates the dynamics of FANCD2 on chromatin to facilitate NHEJ and genome stability.

Dysregulation of the homeostatic balance of histone H3 di- and tri-methyl lysine 27 (H3K27me2/3) levels caused by the mis-sense mutation of histone H3 (H3K27M) is reported to be associated with various types of cancers. In this study, we found that reduction in H3K27me2/3 caused by H3.1K27M, a mutation of H3 variants found in patients with diffuse intrinsic pontine glioma (DIPG), dramatically attenuated the presence of 53BP1 (also known as TP53BP1) foci and the capability of non-homologous end joining (NHEJ) in human dermal fibroblasts. H3.1K27M mutant cells showed increased rates of genomic insertions/deletions and copy number variations, as well as an increase in p53-dependent apoptosis. We further showed that both hypo-H3K27me2/3 and H3.1K27M interacted with FANCD2, a central player in the choice of DNA repair pathway. H3.1K27M triggered the accumulation of FANCD2 on chromatin, suggesting an interaction between H3.1K27M and FANCD2. Interestingly, knockdown of FANCD2 in H3.1K27M cells recovered the number of 53BP1-positive foci, NHEJ efficiency and apoptosis rate. Although these findings in HDF cells may differ from the endogenous regulation of the H3.1K27M mutant in the specific tumor context of DIPG, our results suggest a new model by which H3K27me2/3 facilitates NHEJ and the maintenance of genome stability.This article has an associated First Person interview with the first author of the paper.

Multiple doping structures of the rare-earth atoms in ß-SiAlON:Ce phosphors and their effects on luminescence properties.

The critical doping structures of rare-earth atoms in the promising ß-SiAlON phosphors have long been argued owing to the lack of direct evidence. Here, the exact locations and coordination of the Ce rare-earth atoms in the ß-SiAlON structure have been examined using an atom-resolved Cs-corrected scanning transmission electron microscope. Three different occupation sites for the Ce atoms have been directly observed: two of them are in the structural channel coordinated with six and nine N(O) atoms, respectively; the other one is the unexpected substitution site for Si(Al). The chemical valences and stabilities of the doping Ce ions at the different occupation sites have been evaluated using density functional calculations. Correlation of the different doping structures with the luminescence properties has been investigated by the aid of cathodoluminescence (CL) microanalysis, which verifies the different contribution of the interstitial trivalent Ce ions to the light emission while no luminescence is observed for the substitutional doping of quadrivalent Ce.

Tunable white light emission from single-phased Li2 SrSiO4 :Dy(3+) phosphors by co-doping with Eu(3+).

A series of single-phase full-color emitting Li2 Sr1-x-y SiO4 :xDy(3+) ,yEu(3+) phosphors were synthesized by solid-state reaction and characterized by X-ray diffraction and photoluminescence analyses. The samples showed emission peaks at 488 nm (blue), 572 nm (yellow), 592 nm (orange) and 617 nm (red) under 393 nm excitation. The photoluminescence excitation spectra, comprising the Eu-O charge transfer band and 4f-4f transition bands of Dy(3+) and Eu(3+) , range from 200 to 500 nm. The Commission Internationale de I'Eclairage chromaticity coordinates for Li2 Sr0.98-x SiO4 :0.02Dy(3+) ,xEu(3+) phosphors were simulated. By manipulating Eu(3+) and Dy(3+) concentrations, the color points of Li2 Sr1-x-y SiO4 :xDy(3+) ,yEu(3+) were tuned from the greenish-white region to white light and eventually to reddish-white region, demonstrating that a tunable white light can be obtained by Li2 Sr1-x-y SiO4 :xDy(3+) ,yEu(3+) phosphors. Li2 Sr0.98-x SiO4 :0.02Dy(3+) , xEu(3+) can serve as a white-light-emitting phosphor for phosphor-converted light-emitting diode.

Color tuning of direct white light of lanthanum aluminate with mixed-valence europium.

The generation of direct white-light emission of the coexisting valence-varied europium-lanthanum aluminate through substitution of cations into the host and its resultant adjustment of the energy transfer have been presented. With respect to La(0.99-x)Sr(x)AlO(3-delta):Eu(0.01) and La(0.994)Al(1-x)O(3-delta):Eu(0.006), and Mn(x), Li(0.012), the green-light emission positioned at 515 nm plays a key role to color mix for white light and can be efficiently tuned by adjusting the transfer of energy and relevant transition emissions between the luminous centers of Eu(2+) and Eu(3+)/Mn(2+), via varying amounts of dopants. Direct white-light emission with optimized values of 86 for the color rendering index and 5091 K for the correlated color temperature has been achieved for lanthanum aluminate by this mixed-valence means.

Tunable single-doped single-host full-color-emitting LaAlO(3):Eu phosphor via valence state-controlled means.

A full-color-emitting phosphor of valence-varied Eu doped perovskite-type LaAlO(3) with the aid of energy transfer is demonstrated and its luminescence properties can be tuned through controllable addition of doped ions.

Biosorption of uranium by lake-harvested biomass from a cyanobacterium bloom.

The aim of this work was to study some basic aspects of uranium biosorption by powdered biomass of lake-harvested cyanobacterium water-bloom, which consisted predominantly of Microcystis aeruginosa. The optimum pH for uranium biosorption was between 4.0 and 8.0. The batch sorption reached the equilibrium within 1 h. The isotherm fitted the Freundlich model well. Although the Langmuir model fitted the experiment data well at pH 3.0, 5.0 and 7.0, it did not fit at pH 9.0 and 11.0 at all. This implies that different biosorption mechanisms may be involved at different pH values. 0.1 N HCl was effective in uranium desorption. The results indicated that the naturally abundant biomass of otherwise nuisance cyanobacterium bloom exhibited good potential for application in removal of uranium from aqueous solution.

Neuroprotective effect of docosahexaenoic acid on glutamate-induced cytotoxicity in rat hippocampal cultures.

The neuroprotective effect of docosahexaenoic acid (DHA) on the glutamate-induced cytotoxicity in rat hippocampal cultures was investigated in the present study. DHA at 5-50 microg/ml successfully protected neurons against the cytotoxicity, markedly increased the cell viability, inhibited both nitric oxide (NO) production and calcium influx, and increased the activities of antioxidant enzymes of glutathione peroxidase (GSH-Px) and glutathione reductase (GR). However, it did not alter the levels of glutathione (GSH) as compared to the control. These results suggest that DHA might be a potent neuroprotector. In addition, they may help to improve our understanding of the effect of DHA on neurodegeneration.