| 1. |
- Meyer, Björn, et al.
(författare)
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Effects of an Internet intervention (Deprexis) on severe depression symptoms : Randomized controlled trial
- 2015
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Ingår i: Internet Interventions. - : Elsevier. - 2214-7829. ; 2:1, s. 48-59
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Tidskriftsartikel (refereegranskat)abstract
- BackgroundStudies have shown that certain Internet interventions can help alleviate depression. However, many such interventions contain personal support elements, making it difficult to ascertain whether the program or the support drives the effects. Studies are needed to investigate whether Internet interventions contribute to symptom reduction even when they are delivered without personal support, and even among severely depressed individuals who often receive other forms of treatment.ObjectiveThis randomized controlled trial aimed to examine the effect of an Internet intervention that was deployed without personal support (“Deprexis”) among adults with initially severe depression symptoms.MethodsAdults recruited from a range of sources who had exceeded the threshold for severe depression (PHQ-9 ≥ 15) in a pre-screening assessment and met inclusion criteria were randomized (N = 163) to the intervention (3 months program access; n = 78) or care-as-usual/waitlist control (n = 85). A diagnostic screening interview was administered by telephone at baseline to all participants. Online assessments were administered at baseline, 3 months (post-treatment), and 6 months (follow-up). The main outcome was the Patient Health Questionnaire (PHQ-9) between baseline and post-treatment.ResultsEighty-two percent of randomized participants were reached for the post-treatment assessment. Results for the intention-to-treat (ITT) sample showed significant intervention effects on depression reduction between baseline and post-treatment (linear mixed model [MM], F1,155.6 = 9.00, p < .01, for the time by condition interaction), with a medium between-group effect size, Cohen's d = 0.57 (95% CI: 0.22–0.92). Group differences in depression severity at follow-up were marginally significant in the ITT sample, t (119) = 1.83, p = 0.07, and smaller than at post-treatment (PHQ-9, d = 0.33, 95% CI: − 0.03–0.69). The number needed to treat (NNT) at post-treatment was 5, with 38% of participants in the intervention group achieving response (at least 50% PHQ-9 symptom change, plus post-treatment score < 10), compared to 17% in the control group, p < 0.01. Effects on secondary outcomes, including anxiety, health-related quality of life, and somatic symptoms, were not significant, with the exception of significant effects on anxiety reduction in PP analyses. Early ratings of program helpfulness/alliance (after 3 weeks) predicted pre–post depression reduction, controlling for baseline severity and early symptom change.ConclusionsThese results replicate and extend previous findings by showing that Deprexis can facilitate symptomatic improvement over 3 months and, perhaps to a lesser degree, up until 6 months among adults with initially severe depression.
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| 4. |
- Angelcheva, Liudmila, et al.
(författare)
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Metabolomic analysis of extreme freezing tolerance in Siberian spruce (Picea obovata)
- 2014
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Ingår i: New Phytologist. - : Wiley. - 0028-646X .- 1469-8137. ; 204:3, s. 545-555
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Tidskriftsartikel (refereegranskat)abstract
- Siberian spruce (Picea obovata) is one of several boreal conifer species that can survive at extremely low temperatures (ELTs). When fully acclimated, its tissues can survive immersion in liquid nitrogen. Relatively little is known about the biochemical and biophysical strategies of ELT survival. We profiled needle metabolites using gas chromatography coupled with mass spectrometry (GC-MS) to explore the metabolic changes that occur during cold acclimation caused by natural temperature fluctuations. In total, 223 metabolites accumulated and 52 were depleted in fully acclimated needles compared with pre-acclimation needles. The metabolite profiles were found to develop in four distinct phases, which are referred to as pre-acclimation, early acclimation, late acclimation and fully acclimated. Metabolite changes associated with carbohydrate and lipid metabolism were observed, including changes associated with increased raffinose family oligosaccharide synthesis and accumulation, accumulation of sugar acids and sugar alcohols, desaturation of fatty acids, and accumulation of digalactosylglycerol. We also observed the accumulation of protein and nonprotein amino acids and polyamines that may act as compatible solutes or cryoprotectants. These results provide new insight into the mechanisms of freezing tolerance development at the metabolite level and highlight their importance in rapid acclimation to ELT in P.obovata.
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| 5. |
- Bag, Pushan, 1993-, et al.
(författare)
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Solubilization method for isolation of photosynthetic mega- And super-complexes from conifer thylakoids
- 2021
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Ingår i: Bio-protocol. - 2331-8325. ; 11:17
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Tidskriftsartikel (refereegranskat)abstract
- Photosynthesis is the main process by which sunlight is harvested and converted into chemical energy and has been a focal point of fundamental research in plant biology for decades. In higher plants, the process takes place in the thylakoid membranes where the two photosystems (PSI and PSII) are located. In the past few decades, the evolution of biophysical and biochemical techniques allowed detailed studies of the thylakoid organization and the interaction between protein complexes and cofactors. These studies have mainly focused on model plants, such as Arabidopsis, pea, spinach, and tobacco, which are grown in climate chambers even though significant differences between indoor and outdoor growth conditions are present. In this manuscript, we present a new mild-solubilization procedure for use with “fragile” samples such as thylakoids from conifers growing outdoors. Here, the solubilization protocol is optimized with two detergents in two species, namely Norway spruce (Picea abies) and Scots pine (Pinus sylvestris). We have optimized the isolation and characterization of PSI and PSII multimeric mega- and super-complexes in a close-to-native condition by Blue-Native gel electrophoresis. Eventually, our protocol will not only help in the characterization of photosynthetic complexes from conifers but also in understanding winter adaptation.
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| 6. |
- Cain, Peter, et al.
(författare)
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A novel extended family of stromal thioredoxins
- 2009
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Ingår i: Plant Molecular Biology. - : Springer. - 0167-4412 .- 1573-5028. ; 70:3, s. 273-281
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Tidskriftsartikel (refereegranskat)abstract
- Thioredoxins play key regulatory roles in chloroplasts by linking photosynthetic light reactions to a series of plastid functions. In addition to the established groups of thioredoxins, f, m, x, and y, novel plant thioredoxins were also considered to include WCRKC motif proteins, CDSP32, the APR proteins, the lilium proteins and HCF164. Despite their important roles, the subcellular locations of many novel thioredoxins has remained unknown. Here, we report a study of their subcellular location using the cDNA clone resources of TAIR. In addition to filling all gaps in the subcellular map of the established chloroplast thioredoxins f, m, x and y, we show that the members of the WCRKC family are targeted to the stroma and provide evidence for a stromal location of the lilium proteins. The combined data from this and related studies indicate a consistent stromal location of the known Arabidopsis chloroplast thioredoxins except for thylakoid-bound HCF164.
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| 7. |
- Carlberg, Inger, et al.
(författare)
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A novel plant protein undergoing light-induced phosphorylation and release from the photosynthetic thylakoid membranes
- 2003
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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 .- 1091-6490. ; 100:2, s. 757-62
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Tidskriftsartikel (refereegranskat)abstract
- The characteristics of a phosphoprotein with a relative electrophoretic mobility of 12 kDa have been unknown during two decades of studies on redox-dependent protein phosphorylation in plant photosynthetic membranes. Digestion of this protein from spinach thylakoid membranes with trypsin and subsequent tandem nanospray-quadrupole-time-of-flight mass spectrometry of the peptides revealed a protein sequence that did not correspond to any previously known protein. Sequencing of the corresponding cDNA uncovered a gene for a precursor protein with a transit peptide followed by a strongly basic mature protein with a molecular mass of 8,640 Da. Genes encoding homologous proteins were found on chromosome 3 of Arabidopsis and rice as well as in ESTs from 20 different plant species, but not from any other organisms. The protein can be released from the membrane with high salt and is also partially released in response to light-induced phosphorylation of thylakoids, in contrast to all other known thylakoid phosphoproteins, which are integral to the membrane. On the basis of its properties, this plant-specific protein is named thylakoid soluble phosphoprotein of 9 kDa (TSP9). Mass spectrometric analyses revealed the existence of non-, mono-, di-, and triphosphorylated forms of TSP9 and phosphorylation of three distinct threonine residues in the central part of the protein. The phosphorylation and release of TSP9 from the photosynthetic membrane on illumination favor participation of this basic protein in cell signaling and regulation of plant gene expression in response to changing light conditions.
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| 8. |
- Chen, Yang-Er, et al.
(författare)
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Comparison of methods for extracting thylakoid membranes of Arabidopsis plants
- 2016
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Ingår i: Physiologia Plantarum. - : Wiley. - 0031-9317 .- 1399-3054. ; 156:1, s. 3-12
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Tidskriftsartikel (refereegranskat)abstract
- Robust and reproducible methods for extracting thylakoid membranes are required for the analysis of photosynthetic processes in higher plants such as Arabidopsis. Here, we compare three methods for thylakoid extraction using two different buffers. Method I involves homogenizing the plant material witha metal/glass blender; method II involves manually grinding the plant materialin ice-cold grinding buffer with a mortar and method III entails snap-freezing followed by manual grinding with a mortar, after which the frozen powder is thawed in isolation buffer. Thylakoid membrane samples extracted using each method were analyzed with respect to protein and chlorophyll content, yields relative to starting material, oxygen-evolving activity, protein complex content and phosphorylation. We also examined how the use of fresh and frozen thylakoid material affected the extracts’ contents of protein complexes. The use of different extraction buffers did not significantly alter the protein contentof the extracts in any case. Method I yielded thylakoid membranes with the highest purity and oxygen-evolving activity. Method III used low amounts of starting material and was capable of capturing rapid phosphorylation changes in the sample at the cost of higher levels of contamination. Method II yielded thylakoid membrane extracts with properties intermediate between those obtained with the other two methods. Finally, frozen and freshly isolated thylakoid membranes performed identically in blue native-polyacrylamide gel electrophoresis experiments conducted in order to separate multimeric protein supracomplexes.
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| 9. |
- Chen, Yang-Er, et al.
(författare)
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The Low Molecular Mass Photosystem II Protein PsbTn is Important for Light Acclimation
- 2019
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Ingår i: Plant Physiology. - Rockville : American Society of Plant Biologists. - 0032-0889 .- 1532-2548. ; 179:4, s. 1739-1753
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Tidskriftsartikel (refereegranskat)abstract
- Photosystem II (PSII) is a supramolecular complex containing over 30 protein subunits and a large set of cofactors including various pigments and quinones as well as Mn, Ca, Cl, and Fe ions. Eukaryotic PSII complexes contain many subunits not found in their bacterial counterparts, including the proteins PsbP, PsbQ, PsbS, and PsbW, as well as the highly homologous, low molecular mass subunits PsbTn1 and PsbTn2 whose function is currently unknown. To determine the function of PsbTn1 and PsbTn2, we generated single and double psbTn1 and psbTn2 knock-out mutants in Arabidopsis thaliana. Cross-linking and reciprocal co-immunoprecipitation experiments revealed that PsbTn is a lumenal PSII protein situated next to the cytochrome b559 subunit PsbE. The removal of the PsbTn proteins decreased the oxygen evolution rate and PSII core phosphorylation level but increased the susceptibility of PSII to photoinhibition and the production of reactive oxygen species. The assembly and stability of PSII were unaffected, indicating that the deficiencies of the psbTn1 psbTn2 double mutants are due to structural changes. Double mutants exhibited a higher rate of non-photochemical quenching of excited states than the wild type and single mutants, as well as slower state transition kinetics and a lower quantum yield of PSII when grown in the field. Based on these results, we propose that the main function of the PsbTn proteins is to enable PSII to acclimate to light shifts or intense illumination.
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| 10. |
- Cheregi, Otilia, et al.
(författare)
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Presence of state transitions in the cryptophyte alga Guillardia theta
- 2015
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Ingår i: Journal of Experimental Botany. - : Oxford University Press. - 0022-0957 .- 1460-2431. ; 66:20, s. 6461-6470
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Tidskriftsartikel (refereegranskat)abstract
- Plants and algae have developed various regulatory mechanisms for optimal delivery of excitation energy to the photosystems even during fluctuating light conditions; these include state transitions as well as non-photochemical quenching. The former process maintains the balance by redistributing antennae excitation between the photosys-tems, meanwhile the latter by dissipating excessive excitation inside the antennae. In the present study, these mecha-nisms have been analysed in the cryptophyte alga Guillardia theta. Photoprotective non-photochemical quenching was observed in cultures only after they had entered the stationary growth phase. These cells displayed a diminished overall photosynthetic efficiency, measured as CO2 assimilation rate and electron transport rate. However, in the logarithmic growth phase G. theta cells redistributed excitation energy via a mechanism similar to state transitions. These state transitions were triggered by blue light absorbed by the membrane integrated chlorophyll a/c antennae, and green light absorbed by the lumenal biliproteins was ineffective. It is proposed that state transitions in G. thetaare induced by small re-arrangements of the intrinsic antennae proteins, resulting in their coupling/uncoupling to the photosystems in state 1 or state 2, respectively. G. theta therefore represents a chromalveolate algae able to perform state transitions.
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