Light controllable siRNAs regulate gene suppression and phenotypes in cells

Small interfering RNA (siRNA) is widely recognized as a powerful tool for targeted gene silencing. However, siRNA gene silencing occurs during transfection, limiting its use is in kinetic studies, deciphering toxic and off-target effects and phenotypic assays requiring temporal, and/or spatial regulation. We developed a novel controllable siRNA (csiRNA) that is activated by light. A single photo removable group is coupled during oligonucleotide synthesis to the 5' end of the antisense strand of the siRNA, which blocks the siRNA's activity. A low dose of light activates the siRNA, independent of transfection resulting in knock down of specific target mRNAs and proteins (GAPDH, p53, survivin, hNuf2) without stimulating non-specific effects such as regulated protein kinase PKR and induction of the interferon response. We demonstrate survivin and hNuf2 csiRNAs temporally knockdown their mRNAs causing multinucleation and cell death by mitotic arrest, respectively. Furthermore, we demonstrate a dose-dependent light regulation of hNuf2 csiRNA activity and resulting phenotype. The light controllable siRNAs are introduced into cells using commercially available reagents including the MPG peptide based delivery system. The csiRNAs are comparable to standard siRNAs in their transfection efficiency and potency of gene silencing. This technology should be of interest for phenotypic assays such as cell survival, cell cycle regulation, and cell development.     

Prostaglandin E2 binding peptide: a potential modulatory agent which acts through suppressing NF-kappaB signaling in RA

In an earlier study, we found PBP inhibited the progress of adjuvant-induced arthritis (AA). This study was aimed at evaluating the inhibitory effects of PBP in terms of NF-κB activation by using immunohistochemical and immunofluorescent technique in vitro and in vivo. IL-1β and TNF-α in serum were detected by method of ELISA. Immunofluorescent results showed that PBP inhibited NF-κB p65 translocation into nucleus. In vivo imaging showed that treatment with PBP decreased the enzyme labeling signal of NF-κB p65. Immunohistochemical staining revealed that PBP suppressed production of NF-κB p65 subunit in the joints and attenuated the productions of IL-1β and TNF-α in serum from AA. Moreover, NF-κB p65 nucleus translocation was prevented by simultaneous incubation with PBP and PGE2 was decreased by PBP through a feedback cycle. We report the first confirmation of the mimotope of PGE2 receptor EP4 modulatory action.     

Radon and thoron exposures for cave residents in Shanxi and Shaanxi provinces

Measurements of natural radiation were carried out in cave dwellings distributed in the Chinese loess plateau. Those dwellings are located in Shanxi and Shaanxi provinces. Radon and thoron gas concentrations were measured using a passive integrating radon-thoron discriminative detector. Concentrations of thoron decay products were estimated from measurements of their deposition rates. A detector was placed at the center of each dwelling for 6 months and replaced with a fresh one for another 6 months. Measurements were conducted in 202 dwellings from August 2001 through August 2002. A short-term measurement was conducted during the observation period. In addition, gamma-ray dose rates were measured both indoors and outdoors with an electronic pocket dosimeter. Radioactivities in soil were determined by gamma-ray spectrometry with a pure germanium detector. Among 193 dwellings, indoor radon concentrations ranged from 19 to 195 Bq m(-3) with a geometric mean (GM) of 57 Bq m(-3), indoor thoron concentrations ranged from 10 to 865 Bq m(-3) with a GM of 153 Bq m(-3), and indoor equilibrium equivalent thoron concentrations ranged from 0.3 to 4.9 Bq m(-3) with a GM of 1.6 Bq m(-3). Arithmetic means of the gamma-ray dose rates were estimated to be 140 nGy h(-1) indoors and 110 nGy h(-1) outdoors. The present study revealed that the presence of thoron is not negligible for accurate radon measurements and thus that special attention should be paid to thoron and its decay products for dose assessment in such an environment. More systematic studies are necessary for a better understanding of thoron and its decay products.     

Molecular dynamics simulation of carboxy and deoxy human cytoglobin in solution

Cytoglobin (Cgb), the fourth member of the vertebrate heme globin family, is widely expressed in mammalian tissues, and reversibly binds to CO, O₂ and other small ligands. The diverse functions of Cgb may include ligand transport, redox reactions and enzymatic catalysis. Recent studies indicate that Cgb is a potential gene medicine for fibrosis and cancer therapy. In the present work, molecular dynamics (MD) simulations were performed to investigate the functionally related structural properties and dynamic characteristics in carboxy and deoxy human Cgb. The simulation results showed that the loop regions and internal cavities were significantly affected through the binding of an exogenous ligand. The AB, GH and EF loops were found to undergo significant rearrangement and this led to distinct cavity adjustments in Xe2, Xe4 and the distal pocket. In addition, solvent accessibility and torsion angle analyses revealed an interactive distal network comprised of His⁸¹(E7), Leu⁴⁶(B10) and Arg⁸⁴(E10). The MD study of carboxy and deoxy human Cgb revealed that CO-ligated Cgb modulates the protein conformation primarily by loop and cavity rearrangements rather than the heme sliding mechanism found in neuroglobin (Ngb). The significant differences between Cgb and Ngb in the loop and cavity properties are presumably linked to their various biological functions.     

50% Sn‐Based Planar Perovskite Solar Cell with Power Conversion Efficiency up to 13.6%

In the present work, a Pb‐assisted two step method is successfully proposed to fabricate high‐quality CH₃NH₃Sn_0.5Pb_0.5I₃ (MASn_0.5Pb_0.5I₃) perovskite film on the indium tin oxide (ITO) glass/poly(3,4‐ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) substrate. The film shows regular crystalline grains with a flat and compact morphology as well as full coverage on the planar PEDOT:PSS substrate. Remarkably, corresponding devices ITO/PEDOT:PSS/MASn_0.5Pb_0.5I₃/C₆₀/2,9‐dimethyl‐4,7‐diphenyl‐1,10‐phenanthroline/Ag are fabricated with high reproducibility, achieving a high power conversion efficiency of 13.6%, which is, to the best of knowledge, the most efficient solar cell based on Sn‐based perovskite.     

A new species report of Caroperla Kohno, 1946 (Plecoptera: Perlidae) from China

A brief taxonomic synopsis of the genus Caroperla Kohno, 1946 is presented and its further generic delimitation is defined along with a new species, C. siveci sp. n. from the Wuyishan Mountain of Fujian, China. It represents the first report of the genus from China and the third species of the genus. The morphological comparison of the new species with the two other known species is given.     

Astrocytes protect neurons from nitric oxide toxicity by a glutathione-dependent mechanism

Nitric oxide (NO) contributes to neuronal death in cerebral ischemia and other conditions. Astrocytes are anatomically well positioned to shield neurons from NO because astrocyte processes surround most neurons. In this study, the capacity of astrocytes to limit NO neurotoxicity was examined using a cortical co-culture system. Astrocyte-coated dialysis membranes were placed directly on top of neuronal cultures to provide a removable astrocyte layer between the neurons and the culture medium. The utility of this system was tested by comparing neuronal death produced by glutamate, which is rapidly cleared by astrocytes, and N-methyl-D-aspartate (NMDA), which is not. The presence of an astrocyte layer increased the LD(50) for glutamate by approximately four-fold, but had no effect on NMDA toxicity. Astrocyte effects on neuronal death produced by the NO donors S-nitroso-N-acetyl penicillamine and spermine NONOate were examined by placing these compounds into the medium of co-cultures containing either a control astrocyte layer or an astrocyte layer depleted of glutathione by prior exposure to buthionine sulfoximine. Neurons in culture with the glutathione-depleted astrocytes exhibited a two-fold increase in cell death over a range of NO donor concentrations. These findings suggest that astrocytes protect neurons from NO toxicity by a glutathione-dependent mechanism.     

Cage opening and fragmentation of C60 fullerene induced by an ultrashort laser pulse

Response of C₆₀ fullerene to a 40 fs full-width at half-maximum laser pulse with a photon energy of 2.0 eV and different laser intensities is studied by semiclassical dynamics simulation technique. The simulation results show that soon after the irradiation with a strong laser pulse, many C–C bonds abruptly break but no fragments are produced. The breaking of multiple C–C bonds induces a quick increase in the kinetic energy and potential energy and a decrease in electronic energy. These results suggest that the opening of the C₆₀ cage is an effective channel for the conversion of electronic energy to kinetic energy for the electronically excited C₆₀ fullerene.