| 1. |
- Adolfsson, Karl, et al.
(författare)
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Ingestion of gallium phosphide nanowires has no adverse effect on Drosophila tissue function.
- 2013
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Ingår i: Nanotechnology. - : IOP Publishing. - 0957-4484 .- 1361-6528. ; 24:28
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Tidskriftsartikel (refereegranskat)abstract
- Engineered nanoparticles have been under increasing scrutiny in recent years. High aspect ratio nanoparticles such as carbon nanotubes and nanowires have raised safety concerns due to their geometrical similarity to asbestos fibers. III-V epitaxial semiconductor nanowires are expected to be utilized in devices such as LEDs and solar cells and will thus be available to the public. In addition, clean-room staff fabricating and characterizing the nanowires are at risk of exposure, emphasizing the importance of investigating their possible toxicity. Here we investigated the effects of gallium phosphide nanowires on the fruit fly Drosophila melanogaster. Drosophila larvae and/or adults were exposed to gallium phosphide nanowires by ingestion with food. The toxicity and tissue interaction of the nanowires was evaluated by investigating tissue distribution, activation of immune response, genome-wide gene expression, life span, fecundity and somatic mutation rates. Our results show that gallium phosphide nanowires applied through the diet are not taken up into Drosophila tissues, do not elicit a measurable immune response or changes in genome-wide gene expression and do not significantly affect life span or somatic mutation rate.
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| 2. |
- Brändén, Gisela, 1975, et al.
(författare)
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Coherent diffractive imaging of microtubules using an X-ray laser.
- 2019
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Ingår i: Nature communications. - : Springer Science and Business Media LLC. - 2041-1723. ; 10:1
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Tidskriftsartikel (refereegranskat)abstract
- X-ray free electron lasers (XFELs) create new possibilities for structural studies of biological objects that extend beyond what is possible with synchrotron radiation. Serial femtosecond crystallography has allowed high-resolution structures to be determined from micro-meter sized crystals, whereas single particle coherent X-ray imaging requires development to extend the resolution beyond a few tens of nanometers. Here we describe an intermediate approach: the XFEL imaging of biological assemblies with helical symmetry. We collected X-ray scattering images from samples of microtubules injected across an XFEL beam using a liquid microjet, sorted these images into class averages, merged these data into a diffraction pattern extending to 2nm resolution, and reconstructed these data into a projection image of the microtubule. Details such as the 4nm tubulin monomer became visible in this reconstruction. These results illustrate the potential of single-molecule X-ray imaging of biological assembles with helical symmetry at room temperature.
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| 3. |
- Båth, Petra, 1988, et al.
(författare)
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Lipidic cubic phase serial femtosecond crystallography structure of a photosynthetic reaction centre
- 2022
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Ingår i: Acta Crystallographica Section D-Structural Biology. - : International Union of Crystallography (IUCr). - 2059-7983. ; 78, s. 698-708
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Tidskriftsartikel (refereegranskat)abstract
- Serial crystallography is a rapidly growing method that can yield structural insights from microcrystals that were previously considered to be too small to be useful in conventional X-ray crystallography. Here, conditions for growing microcrystals of the photosynthetic reaction centre of Blastochloris viridis within a lipidic cubic phase (LCP) crystallization matrix that employ a seeding protocol utilizing detergent-grown crystals with a different crystal packing are described. LCP microcrystals diffracted to 2.25 angstrom resolution when exposed to XFEL radiation, which is an improvement of 0.15 angstrom over previous microcrystal forms. Ubiquinone was incorporated into the LCP crystallization media and the resulting electron density within the mobile Q(B) pocket is comparable to that of other cofactors within the structure. As such, LCP microcrystallization conditions will facilitate time-resolved diffraction studies of electron-transfer reactions to the mobile quinone, potentially allowing the observation of structural changes associated with the two electron-transfer reactions leading to complete reduction of the ubiquinone ligand.
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| 4. |
- Dods, Robert, 1989, et al.
(författare)
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From Macrocrystals to Microcrystals: A Strategy for Membrane Protein Serial Crystallography.
- 2017
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Ingår i: Structure. - : Elsevier BV. - 1878-4186 .- 0969-2126. ; 25:9, s. 1461-1468
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Tidskriftsartikel (refereegranskat)abstract
- Serial protein crystallography was developed at X-ray free-electron lasers (XFELs) and is now also being applied at storage ring facilities. Robust strategies for the growth and optimization of microcrystals are needed to advance the field. Here we illustrate a generic strategy for recovering high-density homogeneous samples of microcrystals starting from conditions known to yield large (macro) crystals of the photosynthetic reaction center of Blastochloris viridis (RCvir). We first crushed these crystals prior to multiple rounds of microseeding. Each cycle of microseeding facilitated improvements in the RCvir serial femtosecond crystallography (SFX) structure from 3.3-Å to 2.4-Å resolution. This approach may allow known crystallization conditions for other proteins to be adapted to exploit novel scientific opportunities created by serial crystallography.
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| 5. |
- Dods, Robert, 1989, et al.
(författare)
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Ultrafast structural changes within a photosynthetic reaction centre.
- 2021
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Ingår i: Nature. - : Springer Science and Business Media LLC. - 1476-4687 .- 0028-0836. ; 589:7841, s. 310-314
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Tidskriftsartikel (refereegranskat)abstract
- Photosynthetic reaction centres harvest the energy content of sunlight by transporting electrons across an energy-transducing biological membrane. Here we use time-resolved serial femtosecond crystallography1 using an X-ray free-electron laser2 to observe light-induced structural changes in the photosynthetic reaction centre of Blastochloris viridis on a timescale of picoseconds. Structural perturbations first occur at the special pair of chlorophyll molecules of the photosynthetic reaction centre that are photo-oxidized by light. Electron transfer to the menaquinone acceptor on the opposite side of the membrane induces a movement of this cofactor together with lower amplitude protein rearrangements. These observations reveal how proteins use conformational dynamics to stabilize the charge-separation steps of electron-transfer reactions.
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| 6. |
- Hammarin, Greger, et al.
(författare)
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Enhanced laminin adsorption on nanowires compared to flat surfaces.
- 2014
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Ingår i: Colloids and Surfaces B: Biointerfaces. - : Elsevier BV. - 1873-4367 .- 0927-7765. ; 122, s. 85-89
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Tidskriftsartikel (refereegranskat)abstract
- Semiconductor nanowires are widely used to interface living cells, and numerous nanowire-based devices have been developed to manipulate or sense cell behavior. We have, however, little knowledge on the nature of the cell-nanowire interface. Laminin is an extracellular matrix protein promoting cell attachment and growth. Here, we used a method based on fluorescence microscopy and measured the relative amount of laminin adsorbed on nanowires compared to flat surfaces. The amount of adsorbed laminin per surface area is up to 4 times higher on 55nm diameter gallium phosphide nanowires compared to the flat gallium phosphide surface between the nanowires. We show that this enhanced adsorption on nanowires cannot be attributed to electrostatic effects, nor to differences in surface chemistry, but possibly to pure geometrical effects, as increasing the nanowire diameter results in a decreased amount of adsorbed protein. The increased adsorption of laminin on nanowires may explain the exceptionally beneficial properties of nanowire substrates for cellular growth reported in the literature since laminin is often used as surface coating prior to cell cultures in order to promote cell growth, and also because primary cell suspensions contain endogenous laminin.
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| 7. |
- Hammarin, Greger, 1981
(författare)
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Microtubule structure and function as perturbed by electromagnetic fields
- 2022
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Frontlinjen för strukturbiologisk forskning ligger idag i att avbilda proteiner i rörelse. För att förstå hur proteiner fungerar rent strukturellt krävs avbildningsmetoder med en tid- och rums-upplösning anpassad för den specifika biologiska funktionen. Tidigare forskning rörande ljuskänsliga proteinkomplexs reaktion på ljus har genomförts med hög tidsmässig upplösning, men det saknas en generell metod för att initiera och koordinera proteinrörelser. Tidigare forskning har också indikerat att protein i starka elektromagnetiska fält kan induceras att uppvisa relevanta strukturella rörelser. Mikrotubuli är essentiella komponenter i cellskelettet i allt eukaryot liv. De är i huvudsak uppbyggda av de två proteiner alfa- och beta-tubulin. Tillsammans bildar de en heterodimer som kan organisera sig i en tubformade mikrotubuli. Denna avhandling inkluderar tre undersökningar av mikroubulis struktur och funktion. Den mest högupplösta avbildningen av mikrotubuli, och proteiner generellt, baseras idag på metoder som kräver att proteinkomplexet fryses ned eller torkas ut. Avhandlingens första studie utgör ett försök att avbilda mikrotubuli under fysiologiskt mer relevanta omständigheter, i en rumstempererad lösning. Den rumsliga upplösning med vilken mikrotubuli avbildades är lägre än vad som uppnåtts med beprövade metoder, men samtidigt visar studien på potentialen att avbilda enskilda partiklar i flytande lösning och vid rumstemperatur. I denna avhandling presenteras även två studier som avsåg att undersöka om alternerande elektromagnetiska fält, med frekvenser motsvarande dagens mobiltelefoni och Wifi, påverkar mikrotubulis struktur och funktion. Studierna fann ingen sådan påverkan utöver de som kan associeras med värmeutveckling eller rumslig orientering.
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| 8. |
- Hällström, Waldemar, et al.
(författare)
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Fifteen-Piconewton Force Detection from Neural Growth Cones Using Nanowire Arrays
- 2010
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Ingår i: Nano Letters. - : American Chemical Society (ACS). - 1530-6992 .- 1530-6984. ; 10:3, s. 782-787
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Tidskriftsartikel (refereegranskat)abstract
- We used epitaxially grown monodisperse nanowire arrays to measure cellular forces with a spatial resolution of 1 mu m. Nerve cells were cultured on the array and cellular forces were calculated from the displacement of the nanowire tips. The measurements were done in situ on live cells using confocal microscopy, Forces down to 15 pN were measured on neural growth cones, showing that this method can be used to study the Fine details of growth-cone dynamics.
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| 9. |
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| 10. |
- Lönngren, Johanna, 1985-, et al.
(författare)
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Sustainable Development in Nano-Perspectives : An Innovative Student Initiative
- 2010
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Ingår i: Engineering Education in Sustainable Development, conference proceedings. - : Engineering Education in Sustainable Development, Gothenburg, Sweden.
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Konferensbidrag (refereegranskat)abstract
- This paper describes and discusses a novel class for sustainable development at the faculty of engineering at Lund University, Sweden. Based on personal experience and student questionnaires, the study discusses applied pedagogical approaches (case study, role play, matrix approach) and suggests improvements to the structure of the class. The project is a student initiative, making student involvement and its effects on learning for sustainable development central topics of this paper, thereby challenging the notion of engineering students as passive receivers of education for sustainable development.
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| 11. |
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| 12. |
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| 13. |
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| 14. |
- Safari, Cecilia, 1989, et al.
(författare)
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Time-resolved serial crystallography to track the dynamics of carbon monoxide in the active site of cytochrome c oxidase
- 2023
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Ingår i: Science advances. - 2375-2548. ; 9:49
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Tidskriftsartikel (refereegranskat)abstract
- Cytochrome c oxidase (CcO) is part of the respiratory chain and contributes to the electrochemical membrane gradient in mitochondria as well as in many bacteria, as it uses the energy released in the reduction of oxygen to pump protons across an energy-transducing biological membrane. Here, we use time-resolved serial femtosecond crystallography to study the structural response of the active site upon flash photolysis of carbon monoxide (CO) from the reduced heme a3 of ba3-type CcO. In contrast with the aa3-type enzyme, our data show how CO is stabilized on CuB through interactions with a transiently ordered water molecule. These results offer a structural explanation for the extended lifetime of the CuB-CO complex in ba3-type CcO and, by extension, the extremely high oxygen affinity of the enzyme.
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| 15. |
- Sharma, Amit, et al.
(författare)
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A simple adaptation to a protein crystallography station to facilitate difference X-ray scattering studies
- 2019
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Ingår i: Journal of Applied Crystallography. - : International Union of Crystallography (IUCr). - 0021-8898 .- 1600-5767. ; 52, s. 378-386
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Tidskriftsartikel (refereegranskat)abstract
- The X-ray crystallography station I911-2 at MAXLab II (Lund, Sweden) has been adapted to enable difference small- and wide-angle X-ray scattering (SAXS/WAXS) data to be recorded. Modifications to the beamline included a customized flow cell, a motorized flow cell holder, a helium cone, a beam stop, a sample stage and a sample delivery system. This setup incorporated external devices such as infrared lasers, LEDs and reaction mixers to induce conformational changes in macromolecules. This platform was evaluated through proof-of-principle experiments capturing light-induced conformational changes in phytochromes. A difference WAXS signature of conformational changes in a plant aquaporin was also demonstrated using caged calcium.
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| 16. |
- Sharma, Amit, et al.
(författare)
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A simple adaptation to a protein crystallography station to facilitate difference X-ray scattering studies
- 2019
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Ingår i: Journal of Applied Crystallography. - 1600-5767. ; 52:2, s. 378-386
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Tidskriftsartikel (refereegranskat)abstract
- The X-ray crystallography station I911-2 at MAXLab II (Lund, Sweden) has been adapted to enable difference small- and wide-angle X-ray scattering (SAXS/WAXS) data to be recorded. Modifications to the beamline included a customized flow cell, a motorized flow cell holder, a helium cone, a beam stop, a sample stage and a sample delivery system. This setup incorporated external devices such as infrared lasers, LEDs and reaction mixers to induce conformational changes in macromolecules. This platform was evaluated through proof-of-principle experiments capturing light-induced conformational changes in phytochromes. A difference WAXS signature of conformational changes in a plant aquaporin was also demonstrated using caged calcium.
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