| 1. |
- Aad, G., et al.
(författare)
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- 2010
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swepub:Mat__t
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| 2. |
- Aad, G., et al.
(författare)
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- 2011
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swepub:Mat__t
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| 3. |
- Aad, G., et al.
(författare)
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- 2010
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swepub:Mat__t
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| 4. |
- Aad, G., et al.
(författare)
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- 2010
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swepub:Mat__t
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| 5. |
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| 6. |
- Aad, G., et al.
(författare)
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- 2010
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swepub:Mat__t
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| 7. |
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| 8. |
- Chapman, Henry N, et al.
(författare)
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Femtosecond X-ray protein nanocrystallography.
- 2011
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Ingår i: Nature. - : Springer Science and Business Media LLC. - 1476-4687 .- 0028-0836. ; 470:7332, s. 73-7
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Tidskriftsartikel (refereegranskat)abstract
- X-ray crystallography provides the vast majority of macromolecular structures, but the success of the method relies on growing crystals of sufficient size. In conventional measurements, the necessary increase in X-ray dose to record data from crystals that are too small leads to extensive damage before a diffraction signal can be recorded. It is particularly challenging to obtain large, well-diffracting crystals of membrane proteins, for which fewer than 300 unique structures have been determined despite their importance in all living cells. Here we present a method for structure determination where single-crystal X-ray diffraction 'snapshots' are collected from a fully hydrated stream of nanocrystals using femtosecond pulses from a hard-X-ray free-electron laser, the Linac Coherent Light Source. We prove this concept with nanocrystals of photosystem I, one of the largest membrane protein complexes. More than 3,000,000 diffraction patterns were collected in this study, and a three-dimensional data set was assembled from individual photosystem I nanocrystals (∼200nm to 2μm in size). We mitigate the problem of radiation damage in crystallography by using pulses briefer than the timescale of most damage processes. This offers a new approach to structure determination of macromolecules that do not yield crystals of sufficient size for studies using conventional radiation sources or are particularly sensitive to radiation damage.
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| 9. |
- Seibert, M. Marvin, et al.
(författare)
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Single mimivirus particles intercepted and imaged with an X-ray laser
- 2011
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Ingår i: Nature. - : Springer Science and Business Media LLC. - 0028-0836 .- 1476-4687. ; 470:7332, s. 78-81
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Tidskriftsartikel (refereegranskat)abstract
- X-ray lasers offer new capabilities in understanding the structure of biological systems, complex materials and matter under extreme conditions(1-4). Very short and extremely bright, coherent X-ray pulses can be used to outrun key damage processes and obtain a single diffraction pattern from a large macromolecule, a virus or a cell before the sample explodes and turns into plasma(1). The continuous diffraction pattern of non-crystalline objects permits oversampling and direct phase retrieval(2). Here we show that high-quality diffraction data can be obtained with a single X-ray pulse from a noncrystalline biological sample, a single mimivirus particle, which was injected into the pulsed beam of a hard-X-ray free-electron laser, the Linac Coherent Light Source(5). Calculations indicate that the energy deposited into the virus by the pulse heated the particle to over 100,000 K after the pulse had left the sample. The reconstructed exit wavefront (image) yielded 32-nm full-period resolution in a single exposure and showed no measurable damage. The reconstruction indicates inhomogeneous arrangement of dense material inside the virion. We expect that significantly higher resolutions will be achieved in such experiments with shorter and brighter photon pulses focused to a smaller area. The resolution in such experiments can be further extended for samples available in multiple identical copies.
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| 10. |
- Meyer, Sascha W, et al.
(författare)
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APP and APLP2 are essential at PNS and CNS synapses for transmission, spatial learning and LTP
- 2011
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Ingår i: European Molecular Biology Organization. - : Wiley. - 1460-2075. ; 30, s. 2266-2280
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Tidskriftsartikel (refereegranskat)abstract
- Despite its key role in Alzheimer pathogenesis, the physiological function(s) of the amyloid precursor protein (APP) and its proteolytic fragments are still poorly understood. Previously, we generated APPsα knock‐in (KI) mice expressing solely the secreted ectodomain APPsα. Here, we generated double mutants (APPsα‐DM) by crossing APPsα‐KI mice onto an APLP2‐deficient background and show that APPsα rescues the postnatal lethality of the majority of APP/APLP2 double knockout mice. Surviving APPsα‐DM mice exhibited impaired neuromuscular transmission, with reductions in quantal content, readily releasable pool, and ability to sustain vesicle release that resulted in muscular weakness. We show that these defects may be due to loss of an APP/Mint2/Munc18 complex. Moreover, APPsα‐DM muscle showed fragmented post‐synaptic specializations, suggesting impaired postnatal synaptic maturation and/or maintenance. Despite normal CNS morphology and unaltered basal synaptic transmission, young APPsα‐DM mice already showed pronounced hippocampal dysfunction, impaired spatial learning and a deficit in LTP that could be rescued by GABAA receptor inhibition. Collectively, our data show that APLP2 and APP are synergistically required to mediate neuromuscular transmission, spatial learning and synaptic plasticity.
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