| 1. |
- Bergsland, M, et al.
(författare)
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The establishment of neuronal properties is controlled by Sox4 and Sox11
- 2006
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Ingår i: Genes & development. - : Cold Spring Harbor Laboratory. - 0890-9369 .- 1549-5477. ; 20:24, s. 3475-3486
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Tidskriftsartikel (refereegranskat)abstract
- The progression of neurogenesis relies on proneural basic helix–loop–helix (bHLH) transcription factors. These factors operate in undifferentiated neural stem cells and induce cell cycle exit and the initiation of a neurogenic program. However, the transient expression of proneural bHLH proteins in neural progenitors indicates that expression of neuronal traits must rely on previously unexplored mechanisms operating downstream from proneural bHLH proteins. Here we show that the HMG-box transcription factors Sox4 and Sox11 are of critical importance, downstream from proneural bHLH proteins, for the establishment of pan-neuronal protein expression. Examination of a neuronal gene promoter reveals that Sox4 and Sox11 exert their functions as transcriptional activators. Interestingly, the capacity of Sox4 and Sox11 to induce the expression of neuronal traits is independent of mechanisms regulating the exit of neural progenitors from the cell cycle. The transcriptional repressor protein REST/NRSF has been demonstrated to block neuronal gene expression in undifferentiated neural cells. We now show that REST/NRSF restricts the expression of Sox4 and Sox11, explaining how REST/NRSF can prevent precocious expression of neuronal proteins. Together, these findings demonstrate a central regulatory role of Sox4 and Sox11 during neuronal maturation and mechanistically separate cell cycle withdrawal from the establishment of neuronal properties.
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| 2. |
- Modin, Anders, et al.
(författare)
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5 f-Shell correlation effects in dioxides of light actinides studied by O 1s x-ray absorption and emission spectroscopies and first-principles calculations
- 2015
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Ingår i: Journal of Physics. - : IOP Publishing. - 0953-8984 .- 1361-648X. ; 27:31
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Tidskriftsartikel (refereegranskat)abstract
- Soft x-ray emission and absorption spectroscopic data are reported for the O 1s region of a single crystal of UO2, a polycrystalline NpO2 sample, and a single crystal of PuO2. The experimental data are interpreted using first-principles correlated-electron calculations within the framework of the density functional theory with added Coulomb U interaction (DFT+U). A detailed analysis regarding the origin of different structures in the x-ray emission and x-ray absorption spectra is given and the effect of varying the intra-atomic Coulomb interaction-U for the 5f electrons is investigated. Our data indicate that O 1s x-ray absorption and emission spectroscopies can, in combination with DFT+U calculations, successfully be used to study 5f-shell Coulomb correlation effects in dioxides of light actinides. The values for the Coulomb U parameter in these dioxides are derived to be in the range of 4-5 eV.
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| 3. |
- Melas, P. A., et al.
(författare)
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Allele-specific programming of Npy and epigenetic effects of physical activity in a genetic model of depression
- 2013
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Ingår i: Translational Psychiatry. - : Springer Science and Business Media LLC. - 2158-3188. ; 3, s. e255-
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Tidskriftsartikel (refereegranskat)abstract
- Neuropeptide Y (NPY) has been implicated in depression, emotional processing and stress response. Part of this evidence originates from human single-nucleotide polymorphism (SNP) studies. In the present study, we report that a SNP in the rat Npy promoter (C/T; rs105431668) affects in vitro transcription and DNA-protein interactions. Genotyping studies showed that the C-allele of rs105431668 is present in a genetic rat model of depression (Flinders sensitive line; FSL), while the SNP's T-allele is present in its controls (Flinders resistant line; FRL). In vivo experiments revealed binding of a transcription factor (CREB2) and a histone acetyltransferase (Ep300) only at the SNP locus of the FRL. Accordingly, the FRL had increased hippocampal levels of Npy mRNA and H3K18 acetylation; a gene-activating histone modification maintained by Ep300. Next, based on previous studies showing antidepressant-like effects of physical activity in the FSL, we hypothesized that physical activity may affect Npy's epigenetic status. In line with this assumption, physical activity was associated with increased levels of Npy mRNA and H3K18 acetylation. Physical activity was also associated with reduced mRNA levels of a histone deacetylase (Hdac5). Conclusively, the rat rs105431668 appears to be a functional Npy SNP that may underlie depression-like characteristics. In addition, the achieved epigenetic reprogramming of Npy provides molecular support for the putative effectiveness of physical activity as a non-pharmacological antidepressant.
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| 4. |
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| 5. |
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| 6. |
- Butorin, Sergei M., et al.
(författare)
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Chemical Reduction of Actinides Probed by Resonant Inelastic X-ray Scattering
- 2013
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Ingår i: Analytical Chemistry. - : American Chemical Society (ACS). - 0003-2700 .- 1520-6882. ; 85:23, s. 11196-11200
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Tidskriftsartikel (refereegranskat)abstract
- The study addresses the possibilities of immobilizing the mobile species of actinides in the geosphere using metallic iron. Sorption on corroding iron is well-known, but there have been uncertainties with regard to the possibilities of reducing the actinyl species to sparingly soluble oxides and, thereby, permanently immobilizing them. Resonant inelastic X-ray scattering (RIXS) measurements at the actinide 5d edges on Fe foils exposed to uranium(VI) and neptunium(V) solutions in groundwater unambigiously indicate reduction of actinides to, respectively, uranium(IV) and neptunium(IV) on iron surfaces. The reduction manifests itself in an appearance of distinct specific signatures of uranium(IV) and neptunium(IV) in the RIXS profile of 5f-5f excitations. Such signatures and RIXS intensity/cross-section behavior with varying energy of incident photons can be reproduced by model atomic-multiplet calculations of the RIXS spectra. By normalizing the RIXS signal of corresponding 5f-5f excitations to core-to-core 6p-to-5d characteristic fluorescence transitions of actinides, their reduction rates on Fe samples with different exposure to actinide solutions can be estimated. Observed reduction implies similar processes in the nuclear waste canister thus suggesting reduced probability of nuclear waste release with ground waters from the canister.
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| 7. |
- Butorin, S. M., et al.
(författare)
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Resonant inelastic soft X-ray scattering studies of U(VI) reduction on iron surfaces
- 2004
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Ingår i: Materials Research Society Symposium Proceedings. - 0272-9172 .- 1946-4274. ; 807:Scientific Basis for Nuclear Waste Management XXVII, s. 113-118
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Tidskriftsartikel (refereegranskat)abstract
- The authors report on the spectroscopic anal. of several samples relevant to the processes governing the behavior of oxidized U species in groundwater solns. under anoxic conditions. Both Fe samples with different times of exposure to the U(IV) soln. and Fe metal-soln. interfaces in the liq. cell ex-situ and in-situ, resp. Resonant inelastic soft x-ray scattering is sensitive to the chem. state of U. The measurements were performed at a no. of energies of the primary photon beam across the U 5d absorption edge. The results unambiguously indicate the redn. of U(VI) to U(IV) on the Fe surface. [on SciFinder(R)]
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| 8. |
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| 9. |
- Kvashnina, K.O., et al.
(författare)
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Electronic structure of complex copper systems probed by resonant inelastic X-ray scattering at Cu L3 edge
- 2009
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Ingår i: Physica. B, Condensed matter. - : Elsevier B.V.. - 0921-4526 .- 1873-2135. ; 404:20, s. 3559-3566
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Tidskriftsartikel (refereegranskat)abstract
- We have used X-ray absorption (XA) and resonant inelastic X-ray scattering (RIXS) spectroscopies to study a series of copper compounds, namely Cu2O, CuO, Cu(OH)2, CuCl2, Cu2S, CuSO4, malachite (Cu2(CO3)2(OH)2) and atacamite (CuCl2·3Cu(OH)2). Cu 2p XA spectra provide information about oxidation states. Divalent copper gives a single narrow line due to excitations into the empty 3d state, whereas monovalent copper gives a broad band at higher energy due to transitions to 4s states. Chemical shifts of the main line in the Cu2+ XA spectra of different compounds are observed but in some cases they are too small to make a clear distinction between the species. It is shown that RIXS at the Cu 2p edge has a great potential to distinguish between the species due to large differences in spectral shapes for the same energy of the incident photon beam. First evidence for the possibility of detecting chemical composition of copper compounds is presented and discussed in details.
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| 10. |
- Kvashnina, Kristina O., et al.
(författare)
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In situ X-ray absorption study of copper films in ground water solutions
- 2007
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Ingår i: Chemical Physics Letters. - : Elsevier BV. - 0009-2614 .- 1873-4448. ; 447:1-3, s. 54-57
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Tidskriftsartikel (refereegranskat)abstract
- This study illustrates how the damage from copper corrosion can be reduced by modifying the chemistry of the copper surface environment. The surface modification of oxidized copper films induced by chemical reaction with Cl− and in aqueous solutions was monitored by in situ X-ray absorption spectroscopy. The results show that corrosion of copper can be significantly reduced by adding even a small amount of sodium bicarbonate. The studied copper films corroded quickly in chloride solutions, whereas the same solution containing 1.1 mM prevented or slowed down the corrosion processes.
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