| 1. |
- Wöhri, Annemarie, 1976, et al.
(författare)
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A Lipidic-Sponge Phase Screen for Membrane Protein Crystallization
- 2008
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Ingår i: Structure. - : Elsevier BV. - 0969-2126 .- 1878-4186. ; 16:7, s. 1003-1009
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Tidskriftsartikel (refereegranskat)abstract
- A major current deficit in structural biology is the lack of high-resolution structures of eukaryotic membrane proteins, many of which are key drug targets for the treatment of disease. Numerous eukaryotic membrane proteins require specific lipids for their stability and activity, and efforts to crystallize and solve the structures of membrane proteins that do not address the issue of lipids frequently end in failure rather than success. To help address this problem, we have developed a sparse matrix crystallization screen consisting of 48 lipidic-sponge phase conditions. Sponge phases form liquid lipid bilayer environments which are suitable for conventional hanging- and sitting-drop crystallization experiments. Using the sponge phase screen, we obtained crystals of several different membrane proteins from bacterial and eukaryotic sources. We also demonstrate how the screen may be manipulated by incorporating specific lipids such as cholesterol; this modification led to crystals being recovered from a bacterial photosynthetic core complex.
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| 2. |
- Brandsma, J, et al.
(författare)
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A multi-proxy study of anaerobic ammonium oxidation in marine sediments of the Gullmar Fjord, Sweden
- 2011
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Ingår i: ENVIRONMENTAL MICROBIOLOGY REPORTS. - : Wiley. - 1758-2229. ; 3:3, s. 360-366
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Tidskriftsartikel (refereegranskat)abstract
- Anaerobic ammonium oxidation (anammox) is an important process for nitrogen removal in marine pelagic and benthic environments and represents a major sink in the global nitrogen cycle. We applied a suite of complementary methods for the detection and enumeration of anammox activity and anammox bacteria in marine sediments of the Gullmar Fjord, and compared the results obtained with each technique. 15N labelling experiments showed that nitrogen removal through N2 production was essentially limited to the upper 2 cm of the sediment, where anammox contributed 23–47% of the total production. The presence of marine anammox bacteria belonging to the genus ‘Candidatus Scalindua’ was shown by 16S rRNA gene sequence comparison. FISH counts of anammox bacteria correlated well with anammox activity, while quantitative PCR may have underestimated the number of anammox bacterial 16S rRNA gene copies at this site. Potential nitrogen conversion by anammox ranged from 0.6 to 4.8 fmol N cell−1 day−1, in agreement with previous measurements in the marine environment and in bioreactors. Finally, intact ladderane glycerophospholipid concentrations better reflected anammox activity and abundance than ladderane core lipid concentrations, most likely because the core lipid fraction contained a substantial fossil component, especially deeper in the sediment.
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| 3. |
- Carlsson, M. S., et al.
(författare)
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Effects of mussel farms on the benthic nitrogen cycle on the Swedish west coast
- 2012
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Ingår i: Aquaculture Environment Interactions. - : Inter-Research Science Center. - 1869-215X .- 1869-7534. ; 2:2, s. 177-191
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Tidskriftsartikel (refereegranskat)abstract
- The biogeochemical impact of 3 long-line mussel farms (M1, M2 and M3) in Lysekil, Sweden, was investigated from before farm establishment until 1.5 yr after operation had begun. Sedimentation, benthic N flux, total oxygen uptake (TOU) and sulfate reduction rate (SRR) were all significantly increased below the mussel lines at all 3 farms. Effects of increased sedimentation rates were revealed by sediment profile imaging and were highest at Stn M2. These effects increased significantly with time of farm operation, indicating the accumulation of organic matter within sediments over time. Furthermore, more total particulate organic N deposited at farm stations was recycled into the water column compared to at reference stations (similar to 45 versus similar to 13%), indicating an increased release of dissolved inorganic N from sediment below the mussel farms. At one station (M2) with the highest increase in sedimentation rate, denitrification seemed inhibited, while at another station (M3), with a less pronounced increase in sedimentation rate, denitrification was in fact stimulated, accounting for 13% of total sediment N removal. Calculations based on estimated values of N removal through mussel harvest and direct measurements of N input through changes in sedimentation, N regeneration from sediment to the water column through benthic fluxes and changes in denitrification showed, in all cases, a net removal of N from the system, as only 26 to 40% of the total amount of harvested N had been added to the sediments during the growth period.
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| 5. |
- Engström, Pia, 1970, et al.
(författare)
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Anaerobic ammonium oxidation by nitrite (anammox): Implications for N-2 production in coastal marine sediments
- 2005
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Ingår i: Geochimica Et Cosmochimica Acta. - : Elsevier BV. - 0016-7037. ; 69:8, s. 2057-2065
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Tidskriftsartikel (refereegranskat)abstract
- The respiratory reduction of nitrate (denitrification) is acknowledged as the most important process that converts biologically available nitrogen to gaseous dinitrogen (N-2) in marine ecosystems. Recent findings, however, indicate that anaerobic ammonium oxidation by nitrite (anammox) may be an important pathway for N-2 formation and N removal in coastal marine sediments and in anoxic water columns of the oceans. In the present study, we explored this novel mechanism during N mineralization by 15 N amendments (single and coupled additions of (NH4+)-N-15, (NO3-)-N-14 and (NO3-)-N-15) to surface sediments with a wide range of characteristics and overall reactivity. Patterns of N-29/30(2) production in the pore water during closed sediment incubations demonstrated anammox at all 7 of the investigated sites. Stoichiometric calculations revealed that 4% to 79% of total N-2 production was due to this novel route. The relative importance of anammox for N2 release was inversely correlated with remineralized solute production, benthic O-2 consumption, and surface sediment Ch1 a. The observed correlations indicate competition between reductants for pore water nitrite during early diagenesis and that additional factors (e.g. availability of Mn-oxides), superimposed on overall patterns of diagenetic activity, are important for determining absolute and relative rates of anammox in coastal marine sediments. Copyright (c) 2005 Elsevier Ltd
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| 9. |
- Espiard, Stéphanie, et al.
(författare)
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Improved Urinary Cortisol Metabolome in Addison's disease: a Prospective Trial of Dual-Release Hydrocortisone.
- 2021
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Ingår i: The Journal of clinical endocrinology and metabolism. - : The Endocrine Society. - 1945-7197 .- 0021-972X. ; 106:3, s. 814-825
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Tidskriftsartikel (refereegranskat)abstract
- Oral once-daily dual-release hydrocortisone (DR-HC) replacement therapy has demonstrated an improved metabolic profile compared to conventional 3-times-daily (TID-HC) therapy among patients with primary adrenal insufficiency. This effect might be related to a more physiological cortisol profile, but also to a modified pattern of cortisol metabolism.To study cortisol metabolism during DR-HC and TID-HC.Randomized, 12-week, crossover study.DC-HC and same daily dose of TID-HC in patients with primary adrenal insufficiency (n=50) versus healthy subjects (n=124) as control.Urinary corticosteroid metabolites measured by gas chromatography/mass spectrometry on 24-hour urinary collections.Total cortisol metabolites decreased during DR-HC compared to TID-HC (P < 0.001) and reached control values (P = 0.089). During DR-HC, 11β-hydroxysteroid dehydrogenase type 1 (11β-HSD1) activity measured by tetrahydrocortisol+5α-tetrahydrocortisol/tetrahydrocortisone ratio was reduced compared to TID-HC (P < 0.05), but remained increased versus controls (P < 0.001). 11β-HSD2 activity measured by urinary free cortisone/free cortisol ratio was decreased with TID-HC versus controls (P < 0.01) but normalized with DR-HC (P = 0.358). 5α- and 5β-reduced metabolites were decreased with DR-HC compared to TID-HC. Tetrahydrocortisol/5α-tetrahydrocortisol ratio was increased during both treatments, suggesting increased 5β-reductase activity.The urinary cortisol metabolome shows striking abnormalities in patients receiving conventional TID-HC replacement therapy with increased 11β-HSD1 activity that may account for the unfavorable metabolic phenotype in primary adrenal insufficiency. Its change towards normalization with DR-HC may mediate beneficial metabolic effects. The urinary cortisol metabolome may serve as a tool to assess optimal cortisol replacement therapy.
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