| 1. |
- Li, Haoyuan, et al.
(författare)
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Diffraction data from aerosolized Coliphage PR772 virus particles imaged with the Linac Coherent Light Source
- 2020
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Ingår i: Scientific Data. - : NATURE RESEARCH. - 2052-4463. ; 7:1
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Tidskriftsartikel (refereegranskat)abstract
- Single Particle Imaging (SPI) with intense coherent X-ray pulses from X-ray free-electron lasers (XFELs) has the potential to produce molecular structures without the need for crystallization or freezing. Here we present a dataset of 285,944 diffraction patterns from aerosolized Coliphage PR772 virus particles injected into the femtosecond X-ray pulses of the Linac Coherent Light Source (LCLS). Additional exposures with background information are also deposited. The diffraction data were collected at the Atomic, Molecular and Optical Science Instrument (AMO) of the LCLS in 4 experimental beam times during a period of four years. The photon energy was either 1.2 or 1.7keV and the pulse energy was between 2 and 4 mJ in a focal spot of about 1.3 mu m x 1.7 mu m full width at half maximum (FWHM). The X-ray laser pulses captured the particles in random orientations. The data offer insight into aerosolised virus particles in the gas phase, contain information relevant to improving experimental parameters, and provide a basis for developing algorithms for image analysis and reconstruction.
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| 2. |
- Björling, Alexander, 1983, et al.
(författare)
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Ubiquitous Structural Signaling in Bacterial Phytochromes
- 2015
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Ingår i: Journal of Physical Chemistry Letters. - : American Chemical Society (ACS). - 1948-7185. ; 6:17, s. 3379-3383
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Tidskriftsartikel (refereegranskat)abstract
- The phytochrome family of light-switchable proteins has long been studied by biochemical, spectroscopic and crystallographic means, while a direct probe for global conformational signal propagation has been lacking. Using solution X-ray scattering, we find that the photosensory cores of several bacterial phytochromes undergo similar large-scale structural changes upon red-light excitation. The data establish that phytochromes with ordinary and inverted photocycles share a structural signaling mechanism and that a particular conserved histidine, previously proposed to be involved in signal propagation, in fact tunes photoresponse.
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| 3. |
- 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
-
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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| 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. |
- Kurta, Ruslan P., et al.
(författare)
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Correlations in Scattered X-Ray Laser Pulses Reveal Nanoscale Structural Features of Viruses
- 2017
-
Ingår i: Physical Review Letters. - : American Physical Society. - 0031-9007 .- 1079-7114. ; 119:15
-
Tidskriftsartikel (refereegranskat)abstract
- We use extremely bright and ultrashort pulses from an x-ray free-electron laser (XFEL) to measure correlations in x rays scattered from individual bioparticles. This allows us to go beyond the traditional crystallography and single-particle imaging approaches for structure investigations. We employ angular correlations to recover the three-dimensional (3D) structure of nanoscale viruses from x-ray diffraction data measured at the Linac Coherent Light Source. Correlations provide us with a comprehensive structural fingerprint of a 3D virus, which we use both for model-based and ab initio structure recovery. The analyses reveal a clear indication that the structure of the viruses deviates from the expected perfect icosahedral symmetry. Our results anticipate exciting opportunities for XFEL studies of the structure and dynamics of nanoscale objects by means of angular correlations.
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| 7. |
- Munke, Anna, et al.
(författare)
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Data Descriptor : Coherent diffraction of single Rice Dwarf virus particles using hard X-rays at the Linac Coherent Light Source
- 2016
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Ingår i: Scientific Data. - : Nature Publishing Group. - 2052-4463. ; 3
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Tidskriftsartikel (refereegranskat)abstract
- Single particle diffractive imaging data from Rice Dwarf Virus (RDV) were recorded using the Coherent X-ray Imaging (CXI) instrument at the Linac Coherent Light Source (LCLS). RDV was chosen as it is a wellcharacterized model system, useful for proof-of-principle experiments, system optimization and algorithm development. RDV, an icosahedral virus of about 70 nm in diameter, was aerosolized and injected into the approximately 0.1 mu m diameter focused hard X-ray beam at the CXI instrument of LCLS. Diffraction patterns from RDV with signal to 5.9 angstrom ngstrom were recorded. The diffraction data are available through the Coherent X-ray Imaging Data Bank (CXIDB) as a resource for algorithm development, the contents of which are described here.
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| 8. |
- Reddy, Hemanth K. N., et al.
(författare)
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Coherent soft X-ray diffraction imaging of coliphage PR772 at the Linac coherent light source
- 2017
-
Ingår i: Scientia Danica. Series H. Humanistica 4. - : Nature Publishing Group. - 1904-5506 .- 2052-4463. ; 4
-
Tidskriftsartikel (refereegranskat)abstract
- Single-particle diffraction from X-ray Free Electron Lasers offers the potential for molecular structure determination without the need for crystallization. In an effort to further develop the technique, we present a dataset of coherent soft X-ray diffraction images of Coliphage PR772 virus, collected at the Atomic Molecular Optics (AMO) beamline with pnCCD detectors in the LAMP instrument at the Linac Coherent Light Source. The diameter of PR772 ranges from 65-70 nm, which is considerably smaller than the previously reported similar to 600 nm diameter Mimivirus. This reflects continued progress in XFEL-based single-particle imaging towards the single molecular imaging regime. The data set contains significantly more single particle hits than collected in previous experiments, enabling the development of improved statistical analysis, reconstruction algorithms, and quantitative metrics to determine resolution and self-consistency.
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| 9. |
- Arnlund, David, et al.
(författare)
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Visualizing a protein quake with time-resolved X-ray scattering at a free-electron laser
- 2014
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Ingår i: Nature Methods. - : Springer Science and Business Media LLC. - 1548-7091 .- 1548-7105. ; 11:9, s. 923-926
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Tidskriftsartikel (refereegranskat)abstract
- We describe a method to measure ultrafast protein structural changes using time-resolved wide-angle X-ray scattering at an X-ray free-electron laser. We demonstrated this approach using multiphoton excitation of the Blastochloris viridis photosynthetic reaction center, observing an ultrafast global conformational change that arises within picoseconds and precedes the propagation of heat through the protein. This provides direct structural evidence for a 'protein quake': the hypothesis that proteins rapidly dissipate energy through quake-like structural motions.
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| 10. |
- Bagschik, Kai, et al.
(författare)
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Employing soft x-ray resonant magnetic scattering to study domain sizes and anisotropy in Co/Pd multilayers
- 2016
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Ingår i: Physical Review B. - 2469-9950 .- 2469-9969. ; 94:13
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Tidskriftsartikel (refereegranskat)abstract
- It is demonstrated that themagnetic diffraction pattern of the isotropic disorderedmaze pattern is well described utilizing a gamma distribution of domain sizes in a one-dimensional model. From the analysis, the mean domain size and the shape parameter of the distribution are obtained. The model reveals an average domain size that is significantly different from the value that is determined from the peak position of the structure factor in reciprocal space. As a proof of principle, a wedge-shaped (Co-t angstrom/Pd-10 angstrom) 8 multilayer film, that covers the thickness range of the spin-reorientation transition, has been used. By means of soft x-ray resonant magnetic scattering (XRMS) and imaging techniques the thickness-driven evolution of the magnetic properties of the cobalt layers is explored. It is shown that minute changes of the domain pattern concerning domain size and geometry can be investigated and analyzed due to the high sensitivity and lateral resolution of the XRMS technique. The latter allows for the determination of the magnetic anisotropies of the cobalt layers within a thickness range of a few angstroms.
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| 11. |
- Berntsen, Peter, 1974, et al.
(författare)
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Biomechanical effects of environmental and engineered particles on human airway smooth muscle cells
- 2010
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Ingår i: Journal of the Royal Society Interface. - : The Royal Society. - 1742-5689 .- 1742-5662. ; 7:Suppl 3
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Tidskriftsartikel (refereegranskat)abstract
- The past decade has seen significant increases in combustion-generated ambient particles, which contain a nanosized fraction (less than 100 nm), and even greater increases have occurred in engineered nanoparticles (NPs) propelled by the booming nanotechnology industry. Although inhalation of these particulates has become a public health concern, human health effects and mechanisms of action for NPs are not well understood. Focusing on the human airway smooth muscle cell, here we show that the cellular mechanical function is altered by particulate exposure in a manner that is dependent upon particle material, size and dose. We used Alamar Blue assay to measure cell viability and optical magnetic twisting cytometry to measure cell stiffness and agonist-induced contractility. The eight particle species fell into four categories, based on their respective effect on cell viability and on mechanical function. Cell viability was impaired and cell contractility was decreased by (i) zinc oxide (40-100 nm and less than 44 mu m) and copper(II) oxide (less than 50 nm); cell contractility was decreased by (ii) fluorescent polystyrene spheres (40 nm), increased by (iii) welding fumes and unchanged by (iv) diesel exhaust particles, titanium dioxide (25 nm) and copper(II) oxide (less than 5 mu m), although in none of these cases was cell viability impaired. Treatment with hydrogen peroxide up to 500 mu M did not alter viability or cell mechanics, suggesting that the particle effects are unlikely to be mediated by particle-generated reactive oxygen species. Our results highlight the susceptibility of cellular mechanical function to particulate exposures and suggest that direct exposure of the airway smooth muscle cells to particulates may initiate or aggravate respiratory diseases.
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| 12. |
- Berntsen, Peter, 1974, et al.
(författare)
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Dielectric and calorimetric studies of hydrated purple membrane
- 2005
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Ingår i: Biophysical Journal. - : Elsevier BV. - 0006-3495 .- 1542-0086. ; 89:5, s. 3111-3128
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Tidskriftsartikel (refereegranskat)abstract
- Purple membranes (PM) from halobacteria were hydrated to ∼0.4 and ∼0.2 g H 2 O/g of PM and studied by dielectric spectroscopy and differential scanning calorimetry between 120 and 300 K. The dielectric process, attributed to a local (β) relaxation of the confined supercooled water, shows an Arrhenius temperature behavior at low temperatures. In the case of the most hydrated PM a small deviation from the Arrhenius behavior occurs at 190-200 K together with a pronounced endothermic process and an increased activation energy. The observed crossover is accompanied by a reduction of the interlayer spacing due to the partial loss of the intermembrane water. All these effects at ∼200 K are consistent with a scenario where the local relaxation process merges with a nonobservable α-relaxation of the interlayer water, giving rise to a more liquid-like behavior of the interfacial water. For the less hydrated sample the effects are less pronounced and shift to a slightly higher temperature. © 2005 by the Biophysical Society.
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| 13. |
- Berntsen, Peter, 1974
(författare)
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Dynamics of biological membranes and associated water.
- 2008
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- An ingenious assembly of biomolecules and water constitute what we call biological tissue. The presence of water in this assembly is fundamental for the physiological processes and can make the difference between life and death. This thesis is concerned with fundamental questions related to the dynamics of water and its presence around all living cells. The cell is surrounded by a membrane that not only serve as a covering, within which the cell can function, but also by means of transport for life essential species. The capacity of membrane to cooperate with its surrounding is life essential and made possible by to proteins and polar lipids, essentially phospholipids that make the membranes soft. Phospholipids are so called amphipathic molecules, i.e. they have a hydrophobic part (repels water) and a hydrophilic (water loving) part. The hydrophilic region is usually referred to as the head group, and the hydrophobic part is known as the tails. The amphipathic character of the phospholipidsenable them to form lamellar structures called bilayers. In this work hundreds of parallell lipid bilayers on a surface have served as our model system. One bilayer is composed of two layers of lipids arranged so that their hydrocarbon tails face one another, while their charged head groups face the water on either side of the bilayer. We have studied the influence of water in two different membrane systems. One is naturally existing in the plasma membrane of Halobacterium salinarum, which is a bacterium that lives in extremely salty conditions. The other membrane system we have used is from the lecithin group of lipids whose lipid head is made of the alcohol choline (CH3)3N+CH2CH2OH. The lecithins are involved in the transport of other lipids and exist abundantly in the liver and in egg yolk.At biological temperatures there is a mix of many fast and slow motions which makes it diffcult to find out different motions and their possible interrelations. For moderate hydration levels there is no crystallization of the water within the lipid bilayers (not even at temperaures as low as 80K), however there is a substantial slowing-down of the dynamics with decreasing temperature and below a certain temperature the lipids are frozen in a glassy phase. Starting at such low temperatures the onset of different motions of the water and in the lipid systems were probed at successively higher temperatures by using broadband dielectric spectroscopy, differential scanning calorimetry and quasielastic neutron scattering. We found that the molecular motions of the lipids is similar to the molecular motions of glass forming liquids at low temperatures and this behavior was dependent on the amount of water in the lipid system. Transport of charge carriers was also found to be strongly dependent on the water content and this charge transport was changed at the gel-to-liquid transition of the lipids. Furthermore, it was shown that already at 120K (−153◦C) there is local fast motions of the lipid tails, that should be independent of the water content. This work highlights a complex cooperation between water activity and motions in membranes. By shedding light on the coupling between water and membrane motions new insights into the role of water for membrane properties can be gained.
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| 14. |
- Berntsen, Peter, 1974
(författare)
-
Dynamics of Biomembranes and Rheological Properties of Living Cells
- 2011
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- An ingenious assembly of biomolecules and water constitute what we call biological tissue. The presence of water in this assembly is fundamental for the physiological processes and can make the difference between life and death. One of the hallmark features of cellular life is the presence of membranes that separates the cell from the rest of the world and its compartments from each other. There is, however, some fluidity through the membranes. This fluid environment is possible due to the presence of water. The close association and dynamical interplay between lipid membranes and the surrounding water is investigated in the first part of this work. Membranes and water constitute important parts in the macromolecular assemblies and architecture that builds the whole living cell. Cells are highly dynamic with internal structures that constantly remodels and respond to external forces like a viscoelastic material. In many critical biological processes, cells both exert and respond to forces in their surroundings; the mechanical and rheological properties of cells are intimately related to their viscoelastic character which is the topic of the second part of this work. At biological temperatures there is a mix of many types of motions occurring on similar time scales which makes it difficult to separate different motions and elucidate interrelations. However, at low temperatures the different dynamical processes occur on considerably more separated time scales, which simplifies the analysis. Starting at low temperatures the onset of different motions of the water and the lipids were probed at successively higher temperatures by using broadband dielectric spectroscopy, differential scanning calorimetry and quasielastic neutron scattering. We found that the molecular motions of the lipids are similar to the molecular motions of glass forming liquids at low temperatures and the exact dynamical behavior was strongly dependent on the amount of water in the lipid system. The hydration water in lipid membranes modulates the motions of the lipid head groups and vice-versa there are also local lipid motions that influence the water dynamics at low hydration levels. Thus, in lipid membranes there is a strong interplay between water and lipid dynamics.The rheological properties of living cells were probed with optical magnetic twisting cytometry. The results show that the cellular mechanical function is susceptible to particulate exposure, and that the structural relaxation time is faster by nearly a factor 10, but also less temperature dependent close to the membrane compared to in the interior cytoskeletal structures. Moreover, for ATP depleted cells the relaxation dynamics slows down around physiological temperatures, which indicates the importance of ATP hydrolysis for the cellular relaxation dynamics.
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| 15. |
- Berntsen, Peter, 1974, et al.
(författare)
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Interplay between Hydration Water and Headgroup Dynamics in Lipid Bilayers
- 2011
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Ingår i: Journal of Physical Chemistry B. - : American Chemical Society (ACS). - 1520-5207 .- 1520-6106. ; 115:8, s. 1825-1832
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Tidskriftsartikel (refereegranskat)abstract
- In this study, the interplay between water and lipid dynamics has been investigated by broadband dielectric spectroscopy and modulated differential scanning calorimetry (MDSC). The rnultilamellar lipid bilayer system 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC) has been studied over a broad temperature range at three different water contents: about 3, 6, and 9 water molecules per lipid molecule. The results from the dielectric relaxation measurements show that at temperatures
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| 16. |
- Berntsen, Peter, 1974, et al.
(författare)
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The serial millisecond crystallography instrument at the Australian Synchrotron incorporating the "Lipidico" injector
- 2019
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Ingår i: Review of Scientific Instruments. - : AIP Publishing. - 0034-6748 .- 1089-7623. ; 90:8
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Tidskriftsartikel (refereegranskat)abstract
- A serial millisecond crystallography (SMX) facility has recently been implemented at the macromolecular crystallography beamline, MX2 at the Australian Synchrotron. The setup utilizes a combination of an EIGER X 16M detector system and an in-house developed high-viscosity injector, "Lipidico." Lipidico uses a syringe needle to extrude the microcrystal-containing viscous media and it is compatible with commercially available syringes. The combination of sample delivery via protein crystals suspended in a viscous mixture and a millisecond frame rate detector enables high-throughput serial crystallography at the Australian Synchrotron. A hit-finding algorithm, based on the principles of "robust-statistics," is employed to rapidly process the data. Here we present the first SMX experimental results with a detector frame rate of 100 Hz (10 ms exposures) and the Lipidico injector using a mixture of lysozyme microcrystals embedded in high vacuum silicon grease. Details of the experimental setup, sample injector, and data analysis pipeline are designed and developed as part of the Australian Synchrotron SMX instrument and are reviewed here. Published under license by AIP Publishing.
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| 17. |
- Bjorke, Ann Christin Helgesen, et al.
(författare)
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Which exercise prescriptions optimize V̇O2max during cancer treatment? : a systematic review and meta-analysis
- 2019
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Ingår i: Scandinavian Journal of Medicine and Science in Sports. - : John Wiley & Sons. - 0905-7188 .- 1600-0838. ; 29:9, s. 1274-1287
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Forskningsöversikt (refereegranskat)abstract
- The aims of the present systematic review and meta-analysis were to investigate the effect of exercise on maximal oxygen uptake ((V) over dot O(2)max) and to investigate whether exercise frequency, intensity, duration, and volume are associated with changes in (V) over dotO(2)max among adult patients with cancer undergoing treatment. Medline and Embase through OvidSP were searched to identify randomized controlled trials. Two reviewers extracted data and assessed the risk of bias. The overall effect size and differences in effects for different intensities and frequencies were calculated on change scores and post-intervention (V) over dot O(2)max data, and the meta-regression of exercise duration and volumes was analyzed using the Comprehensive Meta-Analysis software. Fourteen randomized controlled trials were included in the systematic review, comprising 1332 patients with various cancer types receiving (neo-) adjuvant chemo-, radio-, and/or hormone therapy. Exercise induced beneficial changes in (V) over dotO(2)max compared to usual care (effect size = 0.46, 95% Confidence Interval = 0.23-0.69). Longer session duration (P = 0.020), and weekly duration (P = 0.010), larger weekly volume (P < 0.001), and shorter intervention duration (P = 0.005) were significantly associated with more beneficial changes in (V) over dot O(2)max. No differences in effects between subgroups with respect to frequency and intensity were found. In conclusion, exercise has beneficial effects on (V) over dotO(2)max in patients with cancer undergoing (neo-) adjuvant treatment. As interventions with larger exercise volumes and longer session durations resulted in larger beneficial changes in (V) over dot O(2)max, exercise frequency, intensity, and duration should be considered carefully for sufficient exercise volume to induce changes in (V) over dot O(2)max for this patient group.
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| 18. |
- Demmelmaier, Ingrid, 1960-, et al.
(författare)
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Does exercise intensity matter for fatigue during (neo-)adjuvant cancer treatment? The Phys-Can randomized clinical trial
- 2021
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Ingår i: Scandinavian Journal of Medicine and Science in Sports. - : Wiley. - 0905-7188 .- 1600-0838. ; 31:5, s. 1144-1159
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Tidskriftsartikel (refereegranskat)abstract
- Exercise during cancer treatment improves cancer-related fatigue (CRF), but the importance of exercise intensity for CRF is unclear. We compared the effects of high- vs low-to-moderate-intensity exercise with or without additional behavior change support (BCS) on CRF in patients undergoing (neo-)adjuvant cancer treatment. This was a multicenter, 2x2 factorial design randomized controlled trial (Clinical Trials NCT02473003) in Sweden. Participants recently diagnosed with breast (n = 457), prostate (n = 97) or colorectal (n = 23) cancer undergoing (neo-)adjuvant treatment were randomized to high intensity (n = 144), low-to-moderate intensity (n = 144), high intensity with BCS (n = 144) or low-to-moderate intensity with BCS (n = 145). The 6-month exercise intervention included supervised resistance training and home-based endurance training. CRF was assessed by Multidimensional Fatigue Inventory (MFI, five subscales score range 4-20), and Functional Assessment of Chronic Illness Therapy-Fatigue scale (FACIT-F, score range 0-52). Multiple linear regression for main factorial effects was performed according to intention-to-treat, with post-intervention CRF as primary endpoint. Overall, 577 participants (mean age 58.7 years) were randomized. Participants randomized to high- vs low-to-moderate-intensity exercise had lower physical fatigue (MFI Physical Fatigue subscale; mean difference −1.05 [95% CI: −1.85, −0.25]), but the difference was not clinically important (ie <2). We found no differences in other CRF dimensions and no effect of additional BCS. There were few minor adverse events. For CRF, patients undergoing (neo-)adjuvant treatment for breast, prostate or colorectal cancer can safely exercise at high- or low-to-moderate intensity, according to their own preferences. Additional BCS does not provide extra benefit for CRF in supervised, well-controlled exercise interventions.
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| 19. |
- Hammarin, Greger, et al.
(författare)
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No observable non-thermal effect of microwave radiation on the growth of microtubules
- 2024
-
Ingår i: Scientific Reports. - 2045-2322 .- 2045-2322. ; 14:1
-
Tidskriftsartikel (refereegranskat)abstract
- Despite widespread public interest in the health impact of exposure to microwave radiation, studies of the influence of microwave radiation on biological samples are often inconclusive or contradictory. Here we examine the influence of microwave radiation of frequencies 3.5 GHz, 20 GHz and 29 GHz on the growth of microtubules, which are biological nanotubes that perform diverse functions in eukaryotic cells. Since microtubules are highly polar and can extend several micrometres in length, they are predicted to be sensitive to non-ionizing radiation. Moreover, it has been speculated that tubulin dimers within microtubules might rapidly toggle between different conformations, potentially participating in computational or other cooperative processes. Our data show that exposure to microwave radiation yields a microtubule growth curve that is distorted relative to control studies utilizing a homogeneous temperature jump. However, this apparent effect of non-ionizing radiation is reproduced by control experiments using an infrared laser or hot air to heat the sample and thereby mimic the thermal history of samples exposed to microwaves. As such, no non-thermal effects of microwave radiation on microtubule growth can be assigned. Our results highlight the need for appropriate control experiments in biophysical studies that may impact on the sphere of public interest.
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| 20. |
- Hammarin, Greger, 1981, et al.
(författare)
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No observable non-thermal effect of microwave radiation on the growth of microtubules
- 2024
-
Ingår i: SCIENTIFIC REPORTS. - 2045-2322. ; 14:1
-
Tidskriftsartikel (refereegranskat)abstract
- Despite widespread public interest in the health impact of exposure to microwave radiation, studies of the influence of microwave radiation on biological samples are often inconclusive or contradictory. Here we examine the influence of microwave radiation of frequencies 3.5 GHz, 20 GHz and 29 GHz on the growth of microtubules, which are biological nanotubes that perform diverse functions in eukaryotic cells. Since microtubules are highly polar and can extend several micrometres in length, they are predicted to be sensitive to non-ionizing radiation. Moreover, it has been speculated that tubulin dimers within microtubules might rapidly toggle between different conformations, potentially participating in computational or other cooperative processes. Our data show that exposure to microwave radiation yields a microtubule growth curve that is distorted relative to control studies utilizing a homogeneous temperature jump. However, this apparent effect of non-ionizing radiation is reproduced by control experiments using an infrared laser or hot air to heat the sample and thereby mimic the thermal history of samples exposed to microwaves. As such, no non-thermal effects of microwave radiation on microtubule growth can be assigned. Our results highlight the need for appropriate control experiments in biophysical studies that may impact on the sphere of public interest.
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| 21. |
- Nogly, P., et al.
(författare)
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Lipidic cubic phase injector is a viable crystal delivery system for time-resolved serial crystallography
- 2016
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Ingår i: Nature Communications. - : Springer Science and Business Media LLC. - 2041-1723. ; 7
-
Tidskriftsartikel (refereegranskat)abstract
- Serial femtosecond crystallography (SFX) using X-ray free-electron laser sources is an emerging method with considerable potential for time-resolved pump-probe experiments. Here we present a lipidic cubic phase SFX structure of the light-driven proton pump bacteriorhodopsin (bR) to 2.3 angstrom resolution and a method to investigate protein dynamics with modest sample requirement. Time-resolved SFX (TR-SFX) with a pump-probe delay of 1ms yields difference Fourier maps compatible with the dark to M state transition of bR. Importantly, the method is very sample efficient and reduces sample consumption to about 1mg per collected time point. Accumulation of M intermediate within the crystal lattice is confirmed by time-resolved visible absorption spectroscopy. This study provides an important step towards characterizing the complete photocycle dynamics of retinal proteins and demonstrates the feasibility of a sample efficient viscous medium jet for TR-SFX.
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| 22. |
- Nogly, P., et al.
(författare)
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Lipidic cubic phase serial millisecond crystallography using synchrotron radiation
- 2015
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Ingår i: Iucrj. - : International Union of Crystallography (IUCr). - 2052-2525. ; 2
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Tidskriftsartikel (refereegranskat)abstract
- Lipidic cubic phases (LCPs) have emerged as successful matrixes for the crystallization of membrane proteins. Moreover, the viscous LCP also provides a highly effective delivery medium for serial femtosecond crystallography (SFX) at X-ray free-electron lasers (XFELs). Here, the adaptation of this technology to perform serial millisecond crystallography (SMX) at more widely available synchrotron microfocus beamlines is described. Compared with conventional microcrystallography, LCP-SMX eliminates the need for difficult handling of individual crystals and allows for data collection at room temperature. The technology is demonstrated by solving a structure of the light-driven proton-pump bacteriorhodopsin (bR) at a resolution of 2.4 angstrom. The room-temperature structure of bR is very similar to previous cryogenic structures but shows small yet distinct differences in the retinal ligand and proton-transfer pathway.
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| 23. |
- Popp, David, et al.
(författare)
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Flow-aligned, single-shot fiber diffraction using a femtosecond X-ray free-electron laser
- 2017
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Ingår i: CYTOSKELETON. - : WILEY. - 1949-3584 .- 1949-3592. ; 74:12, s. 472-481
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Tidskriftsartikel (refereegranskat)abstract
- A major goal for X-ray free-electron laser (XFEL) based science is to elucidate structures of biological molecules without the need for crystals. Filament systems may provide some of the first single macromolecular structures elucidated by XFEL radiation, since they contain one-dimensional translational symmetry and thereby occupy the diffraction intensity region between the extremes of crystals and single molecules. Here, we demonstrate flow alignment of as few as 100 filaments (Escherichia coli pili, F-actin, and amyloid fibrils), which when intersected by femtosecond X-ray pulses result in diffraction patterns similar to those obtained from classical fiber diffraction studies. We also determine that F-actin can be flow-aligned to a disorientation of approximately 5 degrees. Using this XFEL-based technique, we determine that gelsolin amyloids are comprised of stacked -strands running perpendicular to the filament axis, and that a range of order from fibrillar to crystalline is discernable for individual -synuclein amyloids.
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| 24. |
- 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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| 25. |
- Sharma, Amit, et al.
(författare)
-
A simple adaptation to a protein crystallography station to facilitate difference X-ray scattering studies
- 2019
-
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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