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- Lenoir, L, et al.
(författare)
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Bottom-up or top-down control in forest soil microcosms? Effects of soil fauna on fungal biomass and C/N mineralisation
- 2007
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Ingår i: Biology and Fertility of Soils. - : Springer Science and Business Media LLC. - 0178-2762 .- 1432-0789. ; 43:3, s. 281-294
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Tidskriftsartikel (refereegranskat)abstract
- A major question in soil ecology is whether soil food webs are regulated by resources or by predators, i.e. bottom-up (donor) or top-down controlled. We tested the hypothesis that meso- and macrofaunal soil predators can regulate fungivore populations and, thereby cause a top-down cascade effect on fungal biomass and decomposition/mineralisation processes in boreal forest soils. The study was performed as a microcosm experiment with two contrasting soils (humus layers), one poor and one rich in N, and with different combinations of fungivore and predator soil fauna added to "defaunated" soil. In comparison with control microcosms lacking mesofauna (but with nematodes and protozoans), the presence of a diverse Collembola and Oribatida fungivore community significantly reduced the FDA-active fungal biomass or tended to reduce the ergosterol fraction of the fungal biomass in the N-poor humus, but no clear effect could be detected in the N-rich humus. Fungivores as well as fungivores plus predators (a predator community consisting of gamasids, spiders and beetles or a subset thereof) reduced C mineralisation and increased net N mineralisation in both soils. The presence of predators (particularly gamasid mites) reduced collembolan numbers and alleviated the negative effect of fungivores on fungal biomass in the N-poor soil. In the N-rich soil, the presence of predators increased fungal biomass (ergosterol) in relation to the "defaunated" soil. Therefore, a top-down trophic cascade could be detected in the N-poor humus but not in the N-rich humus. Our results suggest that the degree of top-down control in soil fauna communities depends on resource quality and soil fertility.
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| 2. |
- Ryden, M, et al.
(författare)
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Comparative studies of the role of hormone-sensitive lipase and adipose triglyceride lipase in human fat cell lipolysis
- 2007
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Ingår i: American journal of physiology. Endocrinology and metabolism. - : American Physiological Society. - 0193-1849 .- 1522-1555. ; 292:6, s. E1847-E1855
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Tidskriftsartikel (refereegranskat)abstract
- Hormone-sensitive lipase (HSL) and adipose triglyceride lipase (ATGL) regulate adipocyte lipolysis in rodents. The purpose of this study was to compare the roles of these lipases for lipolysis in human adipocytes. Subcutaneous adipose tissue was investigated. HSL and ATGL protein expression were related to lipolysis in isolated mature fat cells. ATGL or HSL were knocked down by RNA interference (RNAi) or selectively inhibited, and effects on lipolysis were studied in differentiated preadipocytes or adipocytes derived from human mesenchymal stem cells (hMSC). Subjects were all women. There were 12 lean controls, 8 lean with polycystic ovary syndrome (PCOS), and 27 otherwise healthy obese subjects. We found that norepinephrine-induced lipolysis was positively correlated with HSL protein levels ( P < 0.0001) but not with ATGL protein. Women with PCOS or obesity had significantly decreased norepinephrine-induced lipolysis and HSL protein expression but no change in ATGL protein expression. HSL knock down by RNAi reduced basal and catecholamine-induced lipolysis. Knock down of ATGL decreased basal lipolysis but did not change catecholamine-stimulated lipolysis. Treatment of hMSC with a selective HSL inhibitor during and/or after differentiation in adipocytes reduced basal lipolysis by 50%, but stimulated lipolysis was inhibited completely. In contrast to findings in rodents, ATGL is of less importance than HSL in regulating catecholamine-induced lipolysis and cannot replace HSL when this enzyme is continuously inhibited. However, both lipases regulate basal lipolysis in human adipocytes. ATGL expression, unlike HSL, is not influenced by obesity or PCOS.
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| 3. |
- Wirén, K, et al.
(författare)
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Treatment with a barrier-strengthening moisturizing cream delays relapse of atopic dermatitis : a prospective and randomized controlled clinical trial
- 2009
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Ingår i: Journal of the European Academy of Dermatology and Venereology. - : Wiley. - 0926-9959 .- 1468-3083. ; 23:11, s. 1267-1272
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Tidskriftsartikel (refereegranskat)abstract
- Background: Standard treatment of atopic dermatitis (AD) is based on topical glucocorticosteroids or calcineurin inhibitors to treat flares combined with moisturizer treatment to alleviate dry skin symptoms. Patients with AD have an abnormal skin barrier function, and strategies for reducing the risks for eczema would be to repair the barrier or prevent barrier dysfunction. Objectives: The objective of this study was to explore the time to relapse of eczema during a 26-week maintenance treatment with a urea containing moisturizer compared to no treatment (neither medical nor non-medicated preparations) after successful clearing of atopic lesions. The moisturizer has previously been shown to improve skin barrier function. Methods: Patients applied betamethasone valerate (0.1%) on eczematous lesions during a 3-week period. Those with cleared eczema entered a 26-week maintenance phase, applying the moisturizer or left the previously affected area untreated. Upon eczema relapse, patients were instructed to contact the clinic and to have the relapse confirmed by the investigator. Results: Fifty-five patients entered the study and 44 patients were included in the maintenance phase (22 using moisturizer twice daily and 22 using no treatment). Median time to relapse for patients treated with moisturizer was > 180 days (duration of the study) compared with 30 days for the no-treatment group. Sixty-eight per cent of the patients treated with the moisturizer and 32% of the untreated patients remained free from eczema during the observation period. Conclusions: Maintenance treatment with a barrier-improving urea moisturizer on previous eczematous areas reduced the risk of relapse to approximately one third of that of no treatment.
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| 5. |
- Wiren, Marianna, et al.
(författare)
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Genomewide analysis of nucleosome density histone acetylation and HDAC function in fission yeast
- 2005
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Ingår i: EMBO Journal. - : Wiley. - 0261-4189 .- 1460-2075. ; 24:16, s. 2906-2918
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Tidskriftsartikel (refereegranskat)abstract
- We have conducted a genomewide investigation into the enzymatic specificity, expression profiles, and binding locations of four histone deacetylases (HDACs), representing the three different phylogenetic classes in fission yeast ( Schizosaccharomyces pombe). By directly comparing nucleosome density, histone acetylation patterns and HDAC binding in both intergenic and coding regions with gene expression profiles, we found that Sir2 ( class III) and Hos2 ( class I) have a role in preventing histone loss; Clr6 ( class I) is the principal enzyme in promoter-localized repression. Hos2 has an unexpected role in promoting high expression of growth-related genes by deacetylating H4K16Ac in their open reading frames. Clr3 ( class II) acts cooperatively with Sir2 throughout the genome, including the silent regions: rDNA, centromeres, mat2/3 and telomeres. The most significant acetylation sites are H3K14Ac for Clr3 and H3K9Ac for Sir2 at their genomic targets. Clr3 also affects subtelomeric regions which contain clustered stress- and meiosis-induced genes. Thus, this combined genomic approach has uncovered different roles for fission yeast HDACs at the silent regions in repression and activation of gene expression.
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