| 1. |
- Andersson, L-O, et al.
(författare)
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A new neutron beam facility
- 2004
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Ingår i: Proc. of the 9th European Particle Accelerator Conference.
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Konferensbidrag (refereegranskat)
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| 2. |
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| 3. |
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| 4. |
- Myneni, S., et al.
(författare)
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Spectroscopic probing of local hydrogen-bonding structures in liquid water
- 2002
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Ingår i: Journal of Physics. - : IOP Publishing. - 0953-8984 .- 1361-648X. ; 14:8, s. L213-L219
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Tidskriftsartikel (refereegranskat)abstract
- We have studied the electronic structure of liquid water using x-ray absorption spectroscopy at the oxygen K edge. Since the x-ray absorption process takes less than a femtosecond, it allows probing of the molecular orbital structure of frozen, local geometries of water molecules at a timescale that has not previously been accessible. Our results indicate that the electronic structure of liquid water is significantly different from that of the solid and gaseous forms, resulting in a pronounced pre-edge feature below the main absorption edge in the spectrum. Theoretical calculations of these spectra suggest that this feature originates from specific configurations of water, for which the H-bond is broken on the H-donating site of the water molecule. This study provides a fingerprint for identifying broken donating H-bonds in the liquid and shows that an unsaturated H-bonding environment exists for a dominating fraction of the water molecules.
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| 5. |
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| 6. |
- Prokofiev, A, et al.
(författare)
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A New Neutron Facility for Single-Event Effect Testing
- 2004
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Ingår i: Proceedings of the 6th International Workshop on Radiation Effects on Semiconductor Devices for Space Application. ; , s. 160-162
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)
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| 7. |
- Alfven, T, et al.
(författare)
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Low-level cadmium exposure and osteoporosis
- 2000
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Ingår i: Journal of bone and mineral research : the official journal of the American Society for Bone and Mineral Research. - : Wiley. - 0884-0431. ; 15:8, s. 1579-1586
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Tidskriftsartikel (refereegranskat)
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| 8. |
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| 9. |
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| 10. |
- Greczynski, G., et al.
(författare)
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Electronic structure of pristine and sodium doped poly(p-pyridine)
- 2001
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Ingår i: Journal of Chemical Physics. - : AIP Publishing. - 0021-9606 .- 1089-7690. ; 114:9, s. 4243-4252
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Tidskriftsartikel (refereegranskat)abstract
- Ultraviolet spectroscopy (UPS) and x-ray photoelectron spectroscopy (XPS) were used to study the valence electronic structures of pristine and sodium doped poly (p-pyridine) (PPY). The UPS spectra were analyzed by studying the density-of-valence-states (DOVS) derived from quantum chemical calculations. The electronic band structure of the PPY chains was also theoretically investigated using the valence effective Hamiltonian (VEH) method. The theoretical approach was found to be more accurate in describing the electronic structure of PPY.
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| 11. |
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| 12. |
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| 13. |
- Persson, Anders, et al.
(författare)
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Effects of enrichment on simple aquatic food webs
- 2001
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Ingår i: American Naturalist. - : University of Chicago Press. - 0003-0147 .- 1537-5323. ; 157:6, s. 654-669
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Tidskriftsartikel (refereegranskat)abstract
- Simple models, based on Lotka-Volterra types of interactions between predator and prey, predict that enrichment will have a destabilizing effect on populations and that equilibrium population densities will change at the top trophic level and every second level below. We experimentally tested these predictions in three aquatic food web configurations subjected to either high or low nutrient additions. The results were structured by viewing the systems as either food chains or webs and showed that trophic level biomass increased with enrichment, which contradicts food chain theory. However, within each trophic level, food web configuration affected the extent to which different functional groups responded to enrichment. By dividing trophic levels into functional groups, based on vulnerability to consumption, we were able to identify significant effects that were obscured when systems were viewed as food chains. The results support the prediction that invulnerable prey may stabilize trophic-level dynamics by replacing other, more vulnerable prey. Furthermore, the vulnerable prey, such as Daphnia and edible algae, responded as predicted by the paradox of enrichment hypothesis; that is, variability in population density increased with enrichment. Hence, by describing ecosystems as a matrix of food web interactions, and by recognizing the interplay between interspecific competition and predation, a more complete description of the ecosystem function was obtained compared to when species were placed into distinct trophic levels.
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| 14. |
- Pettersson, L. G. M., et al.
(författare)
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Electronic structure effects from hydrogen bonding in the liquid phase and in chemisorption : an integrated theory and experimental effort
- 2001
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Ingår i: Journal of Synchrotron Radiation. - 0909-0495 .- 1600-5775. ; 8, s. 136-140
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Tidskriftsartikel (refereegranskat)abstract
- A closely integrated theoretical and experimental effort to understand chemical bonding using X-ray spectroscopic probes is presented. Theoretical techniques to simulate XAS (X-ray absorption spectroscopy), XES (X-ray emission spectroscopy), RIXS (resonant inelastic X-ray scattering) and XPS (X-ray photoelectron spectroscopy) spectra have been developed and implemented within a density functional theory (DFT) framework. In combination with new experimental techniques, such as high-resolution XAS on liquid water under ambient conditions and XES on complicated surface adsorbates, new insight into e.g. hydrogen-bonded systems is obtained. For the (3 x 2) overlayer structure of glycine/Cu(110), earlier work has been extended to include adsorbate-adsorbate interactions. Structures are optimized for large cluster models and for periodic boundary conditions. It is found that specific features in the spectra arise from hydrogen-bonding interactions, which thus have important effects at the molecular-orbital level. XAS on liquid water shows a pronounced pre-edge feature with significant intensity, while the spectrum of ice shows only little intensity in this region. Theoretical spectrum calculations, based on instantaneous structures obtained from molecular-dynamics (MD) simulations, show that the pre-edge feature in the liquid is caused by water molecules with unsaturated hydrogen bonding. Some aspects of the theoretical simulations will be briefly discussed.
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| 15. |
- Plashkevych, O., et al.
(författare)
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Calculations of valence electron binding energies using Kohn-Sham theory and transition potentials
- 2000
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Ingår i: Journal of Electron Spectroscopy and Related Phenomena. - 0368-2048 .- 1873-2526. ; 106:1, s. 51-63
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Tidskriftsartikel (refereegranskat)abstract
- Motivated by the success in computing X-ray photoelectron binding energies and chemical shifts in the core region we apply the Kohn-Sham density functional and transition potential methodology to calculations of binding energies in the valence electron region. Accurate predictions of binding energies over a large energy interval are obtained for a set of molecules for which the quasi-particle approximation holds, but which still have been considered notoriously difficult. The accuracy is found to be a few tenths of an eV in the outermost valence region, slightly poorer in the intermediate region, and seems to be maintained with increasing size of the system.
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| 16. |
- Triguero, L., et al.
(författare)
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Direct experimental measurement of donation/back-donation in unsaturated hydrocarbon bonding to metals
- 2000
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Ingår i: Journal of the American Chemical Society. - : American Chemical Society (ACS). - 0002-7863 .- 1520-5126. ; 122:49, s. 12310-12316
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Tidskriftsartikel (refereegranskat)abstract
- Using resonant and off-resonant X-ray emission spectroscopy, in combination with ground-state density functional calculations, we examine the electronic structure of chemisarbed ethylene and benzene on thr Cu(110) surface to investigate the suitability of the donation/back-donation bonding model given by Dewar(1) and Chart and Duncanson(2) (DCD) for the interaction of unsaturated hydrocarbons with metal surfaces. We give an experimental verification of the DCD model and find donation/back-donation to be twice as large for ethylene as for benzene. In particular, the degree of sigma-pi mixing (rehybridization) is found to correspond to the amount of donation/back-donation, which is put in relation to the aromatic and nonaromatic pi characters of benzene and ethylene, respectively.
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| 17. |
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| 18. |
- Weiss, K., et al.
(författare)
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XPS and XAS investigation of condensed and adsorbed n-octane on a Cu(110) surface
- 2003
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Ingår i: Journal of electron spectroscopy and related phenomena. - : Elsevier. - 0368-2048. ; 128:2-3, s. 179-191
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Tidskriftsartikel (refereegranskat)abstract
- The electronic structure of n-octane adsorbed on Cu(110) is studied by using X-ray absorption spectroscopy (XAS) and X-ray photoelectron spectroscopy (XPS) in combination with cluster model calculations in the framework of density functional theory (DFT). The molecule is found to be well oriented on the surface, which is seen from the high degree of XAS dichroism. Saturated hydrocarbons are commonly considered to physisorb on metals such as Cu(110), but still the C 1s XAS spectra reveal large changes in the electronic structure of the adsorbed octane relative to the free molecule. We find that the XAS resonances corresponding to the molecular Rydberg-valence states are strongly quenched upon adsorption and that there is a significant hybridization of the molecular valence orbitals with the metal bands. In addition to a precise interpretation of the XAS spectra, we present details on the molecular orbital structure of the adsorbed octane molecule. We also discuss shifts in the relative binding energies of the chemically inequivalent carbon atoms in octane upon adsorption, which lead to a narrower XPS spectrum for the adsorbate than the condensed phase spectrum due to the existence of a new relaxation channel.
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| 19. |
- Öström, Henrik, et al.
(författare)
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Bonding of Saturated Hydrocarbons to Metal Surfaces
- 2003
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Ingår i: Physical Review Letters. - : The American Physical Society. - 0031-9007. ; 91:4, s. 046102-
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Tidskriftsartikel (refereegranskat)abstract
- The adsorption of octane on Cu(110) was studied by x-ray absorption and x-ray emission spectroscopy, in combination with spectrum calculations in the framework of density functional theory, as a model system for alkane adsorption on transition metals. Significant electron sharing between the adsorbate and metal surface and involvement of both bonding and antibonding C-H molecular orbitals in the molecule-metal bond was found. The calculations were extended to the case of octane adsorbed on Ni(110), and the position of the metal d band was found to be important for the bonding. The results were generalized to show that this is important for the efficiency as an alkane dehydrogenation catalyst.
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| 20. |
- Öström, H., et al.
(författare)
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Orbital rehybridization in n-octane adsorbed on Cu(110)
- 2003
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Ingår i: Journal of Chemical Physics. - : American Institute of Physics. - 0021-9606. ; 118:8, s. 3782-3789
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Tidskriftsartikel (refereegranskat)abstract
- We have investigated the local electronic structure of n-octane adsorbed on the Cu(110) surface using symmetry-resolved x-ray absorption spectroscopy (XAS) and x-ray emission spectroscopy (XES) in combination with density functional theory (DFT) spectrum calculations. We found new adsorption-induced states in the XE spectra, which we assign to interaction between the bonding CH orbitals and the metal surface. By performing a systematic investigation of the influence of different structural parameters on the XA and XE spectra, we conclude that the molecular geometry is significantly distorted relative to the gas-phase structure. The bonding to the surface leads to a strengthening of the carbon–carbon bonds and a weakening of the carbon–hydrogen bonds, consistent with a rehybridization of the carbons from sp3 to sp2.8. ©2003 American Institute of Physics.
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| 21. |
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| 22. |
- Andersson, J, et al.
(författare)
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A population-based study on the first forty-eight breast cancer patients receiving trastuzumab (Herceptin (R)) on a named patient basis in Sweden
- 2002
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Ingår i: Acta Oncologica. - : Informa UK Limited. - 1651-226X .- 0284-186X. ; 41:3, s. 276-281
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Tidskriftsartikel (refereegranskat)abstract
- Several studies have presented data on the efficacy and tolerability of trastuzumab within clinical trials. As a minority of patients is included in these trials, we undertook this retrospective study to describe trastuzumab therapy in clinical routine and its tolerability. We reviewed the medical records of the first 48 patients in Sweden who received treatment with trastuzumab on a named patient basis with (n = 29) and without (n = 19) chemotherapy. Forty-six patients had metastatic disease and had failed to respond to several prior regimens before starting antibody treatment. Two patients had locally advanced breast cancer failing on given neoadjuvant therapy. Patients with breast cancers with strong (3+) c-erbB-2 overexpression tended to have an improved survival from start of trastuzumab treatment versus those with a moderate (2+) overexpression (p=0.09). Adverse events were registered in 22 patients (46%). The most common and acute side effects were fever and chills (7 patients, 15%). The toxicity seemed reasonable but two patients (4%) suffered serious cardiac events, both of them having received previous treatment with antracyclines.
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| 23. |
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| 24. |
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| 25. |
- Andersson, P, et al.
(författare)
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A constitutively active dioxin/aryl hydrocarbon receptor induces stomach tumors
- 2002
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Ingår i: Proceedings of the National Academy of Sciences of the United States of America. - : Proceedings of the National Academy of Sciences. - 0027-8424. ; 99:15, s. 9990-9995
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Tidskriftsartikel (refereegranskat)abstract
- The dioxin/aryl hydrocarbon receptor (AhR) functions as a ligand-activated transcription factor regulating transcription of a battery of genes encoding xenobiotic metabolizing enzymes. Known receptor ligands are environmental pollutants including polycyclic aromatic hydrocarbons and polychlorinated dioxins. Loss-of-function (gene-disruption) studies in mice have demonstrated that the AhR is involved in toxic effects of dioxins but have not yielded unequivocal results concerning the physiological function of the receptor. Gain-of-function studies therefore were performed to unravel the biological functions of the AhR. A constitutively active AhR expressed in transgenic mice reduced the life span of the mice and induced tumors in the glandular part of the stomach, demonstrating the oncogenic potential of the AhR and implicating the receptor in regulation of cell proliferation.
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| 26. |
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| 27. |
- Brena, Barbara, et al.
(författare)
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Ultrafast Molecular Dissociation of Water in Ice
- 2004
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Ingår i: Physical Review Letters. - : The American Physical Society. - 1079-7114 .- 0031-9007. ; 93, s. 148302-148305
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Tidskriftsartikel (refereegranskat)abstract
- Using x-ray emission and photoemission spectroscopies to measure the occupied valence levels in a thin crystalline ice film, we resolve the ionization-induced dissociation of water in ice on a femtosecond time scale. Isotope substitution confirms proton transfer during the core-hole lifetime in spite of the nonresonant excitation. Through ab initio molecular dynamics on the core-ionized state, the dissociation and spectrum evolution are followed at femtosecond intervals. The theoretical simulations confirm the experimental analysis and allow for a detailed study of the dissociative reaction path.
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| 28. |
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| 29. |
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| 30. |
- Cavalleri, M., et al.
(författare)
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X-absorption spectra of water within a plane-wave Car-Parrinello molecular dynamics framework
- 2004
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Ingår i: Journal of Chemical Physics. - : American Institute of Physics. - 0021-9606 .- 1089-7690. ; 121:20, s. 10065-10075
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Tidskriftsartikel (refereegranskat)abstract
- We describe the implementation of a simple technique to simulate core-level spectra within the Car-Parrinello plane-waves molecular dynamics framework. The x-ray absorption (XA) spectra are generated using the transition potential technique with the effect of the core hole included through a specifically developed pseudopotential for the core-excited atom. Despite the lack of 1s core orbitals in the pseudopotential treatment, the required transition moments are accurately calculated without reconstruction of the all-electron orbitals. The method is applied to the oxygen XA spectra of water in its various aggregation states, but it is transferable to any first-row element. The computed spectra are compared favorably with the results from all-electron cluster calculations, as well as with experimental data. The periodicity of the plane-wave technique improves the description of condensed phases. The molecular dynamics simulation enables in principle a proper treatment of thermal effects and dynamical averaging in complex systems.
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| 31. |
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| 32. |
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| 33. |
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| 34. |
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| 35. |
- Fohlisch, A, et al.
(författare)
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Ground-state interpretation of x-ray emission spectroscopy on adsorbates: CO adsorbed on Cu(100)
- 2000
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Ingår i: PHYSICAL REVIEW B. - : AMERICAN PHYSICAL SOC. - 0163-1829. ; 61:23, s. 16229-16240
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Tidskriftsartikel (refereegranskat)abstract
- The application of resonant inelastic x-ray scattering and resonantly excited x-ray emission to adsorbates has evolved into a powerful technique to investigate the valence electronic structure of adsorbates in an atom-specific and orbital-symmetry-selecti
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| 36. |
- Fohlisch, A, et al.
(författare)
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The bonding of CO to metal surfaces
- 2000
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Ingår i: JOURNAL OF CHEMICAL PHYSICS. - : AMER INST PHYSICS. - 0021-9606. ; 112:4, s. 1946-1958
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Tidskriftsartikel (refereegranskat)abstract
- The atom and symmetry specific properties of x-ray emission spectroscopy have been applied to the investigation of CO adsorbed on Ni(100) and Cu(100) surfaces. In comparison to ab initio electronic structure calculations, obtained in density functional th
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| 37. |
- Friedrich, EB, et al.
(författare)
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Mechanisms of leukotriene B-4-triggered monocyte adhesion
- 2003
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Ingår i: Arteriosclerosis, Thrombosis and Vascular Biology. - 1524-4636. ; 23:10, s. 1761-1767
-
Tidskriftsartikel (refereegranskat)abstract
- Objective - Leukotriene B-4 (LTB4) has been implicated in the trafficking of monocytes to inflammatory pathologicconditions, such as transplant rejection and atherosclerosis. The aim of this study was to determine the mechanisms by which LTB4 contributes to monocyte capture from the circulation. Methods and Results - In in vitro and in vivo vascular models, the lipid chemoattractant LTB4 was an equipotent agonist of monocyte adhesion compared with the chemokine monocyte chemoattractant protein-1 (MCP-1). Adenoviral gene transfer of specific endothelial adhesion molecules and blocking monoclonal antibody studies demonstrated that LTB4 triggers both beta(1)- and beta(2)-integrin-dependent adhesion. Flow cytometry studies suggested that changes in integrin avidity or affinity, rather than alterations of integrin surface expression, were responsible for the chemoattractant-triggered arrest. Surprisingly, in contrast to the peptide chemokine MCP-1, LTB4 did not activate the phosphoinositide 3-kinase pathway, which is a functionally critical step in chemokine-triggered effector functions. Conclusions - LTB4 is a potent trigger of monocyte adhesion under flow yet mediates its effects via pathways that appear to differ from peptide chemoattractants. A better understanding of the mechanisms of LTB4-induced monocyte trafficking might shed insight into disease pathogenesis and pinpoint critical steps for therapeutic intervention for multiple human inflammatory pathologic conditions.
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| 38. |
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| 39. |
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| 40. |
- Gjertsson, Inger, 1962, et al.
(författare)
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Impact of transcription factors AP-1 and NF-kappaB on the outcome of experimental Staphylococcus aureus arthritis and sepsis.
- 2001
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Ingår i: Microbes and infection. - 1286-4579. ; 3:7, s. 527-34
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Tidskriftsartikel (refereegranskat)abstract
- Staphylococcus aureus infection is, despite adequate antibiotic treatment, a disease characterized by high mortality. The bacterium triggers an exaggerated immune response in the host, which on the one hand acts as an efficient defense, but on the other hand gives rise to tissue damage. In this study we have modulated the hosts response to S. aureus by inhibition of nuclear factor kappaB (NF-kappaB) and activator protein-1 (AP-1)-triggered release of pro-inflammatory cytokines and tissue-destructive proteins, respectively. Mice were administered with antisense oligonucleotides (ODN) to the p65 subunit of NF-kappaB and/or a double-stranded oligonucleotide (mCoAP-1) with homology to the murine AP-1 binding site of collagenase IV gene (metalloproteinase-9; MMP-9), solely or in combination with antibiotics. In mice systemically treated with antisense ODN to NF-kappaB p65 alone, the bacterial burden in the kidneys was significantly increased (P = 0.04) The same tendency was seen when mCoAP-1 was administered either alone or in combination with antibiotics. We also found significantly (P = 0.04) elevated levels of IL-6 in p65 antisense treated mice. Surprisingly, this p65 antisense therapy approach, which has turned out to be highly efficient in amelioration of aseptic arthritis and colitis, failed to change the clinical course of either septic arthritis or sepsis. We suggest that interaction with transcription factors leads to increased bacterial burden in vivo, abrogating the potential benefits of the anti-inflammatory properties exerted by these compounds.
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| 41. |
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| 42. |
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| 43. |
- Gumaelius, L., et al.
(författare)
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Comamonas denitrificans sp nov., an efficient denitrifying bacterium isolated from activated sludge
- 2001
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Ingår i: International Journal of Systematic and Evolutionary Microbiology. - : Microbiology Society. - 1466-5026 .- 1466-5034. ; 51, s. 999-1006
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Tidskriftsartikel (refereegranskat)abstract
- To find a biomarker for denitrification in activated sludge, five denitrifying strains isolated from three wastewater treatment plants were studied. These strains were selected from among 1500 isolates for their excellent denitrifying properties. They denitrify quickly and have no lag phase when switching from aerobic to anoxic conditions. All strains have the cd(1)-type of nitrite reductase. The strains are Gram-negative rods and they all grow as filamentous chains when cultivated in liquid solution. The strains differ in colony morphology when grown on nutrient agar. Almost full-length 16S rDNA sequences were determined and phylogenetic analysis revealed that these strains are positioned among members of the genus Comamonas in the beta -subclass of the Proteobacteria. Signature nucleotides and bootstrap percentages were also analysed to verify this position. Strains 110, 123(T), 2.99g, 5.38g and P17 were less than or equal to 96.7 % similar to known strains, but greater than or equal to 99.7 % similar to each other, as judged from their 16S rDNA sequences, and grouped tightly together in the phylogenetic tree. Sequence motifs in the 16S rRNA gene were also found, suggesting the monophyletic origin of these strains. Nevertheless, some strains differed from the others, for example strain 110 branches early from the other strains and 5.38g is phenotypically more inert. Therefore, it is proposed that strains 110, 123(T), 2.99g and P17 are classified into a new species, Comamonas denitrificans sp. nov., while the taxonomic status of strain 5.38g will have to await the outcome of further studies. The type strain of Comamonas denitrificans is 123(T) (ATCC 700936(T)).
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| 44. |
- Gustafsson, Ann, et al.
(författare)
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Role of the glutamyl alpha-carboxylate of the substrate glutathione in the catalytic mechanism of human glutathione transferase A1-1
- 2001
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Ingår i: Biochemistry. - : American Chemical Society (ACS). - 0006-2960 .- 1520-4995. ; 40:51, s. 15835-15845
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Tidskriftsartikel (refereegranskat)abstract
- The Glu alpha-carboxylate of glutathione contributes to the catalytic function of the glutathione transferases. The catalytic efficiency of human glutathione transferase A1-1 (GST A1-1) in the conjugation reaction with 1-chloro-2,4-dinitrobenzene is reduced 15 000-fold if the decarboxylated analogue of glutathione, dGSH (GABA-Cys-Gly), is used as an alternative thiol substrate. The decrease is partially due to an inability of the enzyme to promote ionization of dGSH. The pK(a) value of the thiol group of the natural substrate glutathione decreases from 9.2 to 6.7 upon binding to GST A1-1. However, the lack of the Glu alpha-carboxylate in dGSH raised the pK(a) value of the thiol in the enzymatic reaction to that of the nonenzymatic reaction. Furthermore, K(M)(dGSH) was 100-fold higher than K(M)(GSH). The active-site residue Thr68 forms a hydrogen bond to the Glu alpha-carboxylate of glutathione. Introduction of a carboxylate into GST A1-1 by a T68E mutation increased the catalytic efficiency with dGSH 10-fold and reduced the pK(a) value of the active site bound dGSH by approximately 1 pH unit. The altered pK(a) value is consistent with a catalytic mechanism where the carboxylate contributes to ionization of the glutathione thiol group. With Delta(5)-androstene-3,17-dione as substrate the efficiency of the enzyme is decreased 24 000-fold while with 4-nitrocinnamaldehyde (NCA) the decrease is less than 150-fold. In the latter reaction NCA accepts a proton and, unlike the other reactions studied, may not be dependent on the Glu alpha-carboxylate for deprotonation of the thiol group. An additional function of the Glu alpha-carboxylate may be productive orientation of glutathione within the active site.
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| 45. |
- Hambäck, P. A., et al.
(författare)
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Are associational refuges species-specific?
- 2003
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Ingår i: Functional Ecology. - : Wiley. - 0269-8463 .- 1365-2435. ; :1, s. 87-93
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Tidskriftsartikel (refereegranskat)abstract
- 1. Associational refuges – reduced herbivory on plants in presence of other plant species – may be caused by general and species-specific plant characteristics. However, the species specificity of associational refuges has rarely been evaluated.2. This study examined the species specificity of one known example of associational refuges, the forb Lythrum salicaria and the monophagous insect herbivores Galerucella calmariensis, G. pusilla and Nanophyes marmoratus. The underlying mechanism was examined in order to evaluate connections between mechanisms and species specificity.3. Laboratory studies showed that N. marmoratus but not Galerucella individuals were attracted by odour from undamaged host plants, and that neither species was distracted by odour from Myrica gale.4. Field experiments showed that three non-host plant neighbours with an appearance similar to M. gale, and artificial shrubs, reduced the abundance and egg-laying of Galerucella species by 70–90%. The abundance of N. marmoratus was increased 18-fold on plants in thickets compared with outside.5. The different responses by N. marmoratus and the Galerucella species to plant neighbours app
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| 46. |
- Hilden, L., et al.
(författare)
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Do the extracellular enzymes cellobiose dehydrogenase and manganese peroxidase form a pathway in lignin biodegradation?
- 2000
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Ingår i: FEBS Letters. - 0014-5793 .- 1873-3468. ; 477:02-jan, s. 79-83
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Tidskriftsartikel (refereegranskat)abstract
- The extracellular enzyme manganese peroxidase is believed to degrade lignin by a hydrogen peroxide-dependent oxidation of Mn(II) to the reactive species Mn(III) that attacks the lignin, However, Mn(III) is not able to directly oxidise the non-phenolic lignin structures that predominate in native lignin, We show here that pretreatment of a non-phenolic lignin model compound with another extracellular fungal enzyme, cellobiose dehydrogenase, allows the manganese peroxidase system to oxidise this molecule. The mechanism behind this effect is demethoxylation and/or hydroxylation, i.e. conversion of a nonphenolic structure to a phenolic one, mediated by hydroxyl radicals generated by cellobiose dehydrogenase, This suggests that cellobiose dehydrogenase and manganese peroxidase may act in an extracellular pathway in fungal lignin biodegradation, Analytical techniques used in this paper are reverse-phase high-pressure liquid chromatography, gas chromatography connected to mass spectroscopy and UV-visible spectroscopy.
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| 47. |
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| 48. |
- Johansson, K. E., et al.
(författare)
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Identification of three clusters of canine intestinal spirochaetes by biochemical and 16S rDNA sequence analysis
- 2004
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Ingår i: Journal of Medical Microbiology. - : Microbiology Society. - 0022-2615 .- 1473-5644. ; 53:4, s. 345-350
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Tidskriftsartikel (refereegranskat)abstract
- It has been suggested that canine intestinal spirochaetes consist of Brachyspira pilosicoli and a group of strains that has been provisionally designated 'Brachyspira canis'. The purpose of the present study was to compare 22 spirochaete isolates that were obtained from intestinal specimens of dogs in Sweden (n = 12), Norway (n = 4), the United States (n = 3), Australia (n = 2) and Germany (n = 1) with type and reference strains, as well as field isolates, of Brachyspira species by five biochemical tests and determination of almost-complete 16S rDNA sequences. In an evolutionary tree derived from 16S rDNA sequences, the canine isolates grouped into three clusters. One cluster included the type strain of porcine B. pilosicoli, whereas a second larger cluster, which was monophyletic, contained a canine strain that was identified previously as 'B. canis'. The third cluster consisted of three canine isolates of Scandinavian origin, which grouped together with the type strain of the species Brachyspira alvinipulli (pathogenic to chicken). These three genotypes, which were identified on the basis of 16S rDNA sequences, corresponded to four phenotypic groups based on biochemical testing. Two biochemical tests, hippurate hydrolysis and alpha-galactosidase production, were sufficient for rapid identification of each canine cluster.
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| 49. |
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| 50. |
- Kolczewski, C., et al.
(författare)
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Detailed study of pyridine at the C1s and N1s ionization thresholds : The influence of the vibrational fine structure
- 2001
-
Ingår i: Journal of Chemical Physics. - : AIP Publishing. - 0021-9606 .- 1089-7690. ; 115:14, s. 6426-6437
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Tidskriftsartikel (refereegranskat)abstract
- High resolution, vibrationally resolved, near-edge x-ray absorption fine structure (NEXAFS) spectra at the C 1s and N 1s ionization thresholds of pyridine and deuterated d(5)-pyridine in the gas phase have been recorded. The high resolution of 65 meV (150 meV) at the C s (N 1s) ionization thresholds reveals vibrational structures in the spectra. Detailed ab initio and density functional theory (DFT) calculations were performed to interpret the experimental spectra and to assign the observed peaks. In particular we focused on the previously unexplained intensity ratio for the two components of the C1s -->1 pi* transition. For this transition the vibrational structure is included through a linear coupling model in the DFT calculations and leads to the experimentally observed similar to2:3 intensity ratio between the two pi* components in the C1s spectrum rather than the similar to3:2 ratio obtained without vibrational effects. After inclusion of relaxation effects in the excited states, in addition to the vibrational effects, both theoretical methods yield almost perfect agreement with experiment.
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