| 1. |
- Dahl, Martin, 1984-, et al.
(författare)
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A 2,000-Year Record of Eelgrass (Zostera marina L.) : Colonization Shows Substantial Gains in Blue Carbon Storage and Nutrient Retention
- 2024
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Ingår i: Global Biogeochemical Cycles. - : John Wiley & Sons. - 0886-6236 .- 1944-9224. ; 38:3
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Tidskriftsartikel (refereegranskat)abstract
- Assessing historical environmental conditions linked to habitat colonization is important for understanding long-term resilience and improving conservation and restoration efforts. Such information is lacking for the seagrass Zostera marina, an important foundation species across cold-temperate coastal areas of the Northern Hemisphere. Here, we reconstructed environmental conditions during the last 14,000 years from sediment cores in two eelgrass (Z. marina) meadows along the Swedish west coast, with the main aims to identify the time frame of seagrass colonization and describe subsequent biogeochemical changes following establishment. Based on vegetation proxies (lipid biomarkers), eelgrass colonization occurred about 2,000 years ago after geomorphological changes that resulted in a shallow, sheltered environment favoring seagrass growth. Seagrass establishment led to up to 20- and 24-fold increases in sedimentary carbon and nitrogen accumulation rates, respectively. This demonstrates the capacity of seagrasses as efficient ecosystem engineers and their role in global change mitigation and adaptation through CO2 removal, and nutrient and sediment retention. By combining regional climate projections and landscape models, we assessed potential climate change effects on seagrass growth, productivity and distribution until 2100. These predictions showed that seagrass meadows are mostly at risk from increased sedimentation and hydrodynamic changes, while the impact from sea level rise alone might be of less importance in the studied area. This study showcases the positive feedback between seagrass colonization and environmental conditions, which holds promise for successful conservation and restoration efforts aimed at supporting climate change mitigation and adaptation, and the provision of several other crucial ecosystem services. © 2024. The Authors.
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| 2. |
- Dahl, Martin, 1984-, et al.
(författare)
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First assessment of seagrass carbon accumulation rates in Sweden: A field study from a fjord system at the Skagerrak coast
- 2023
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Ingår i: PLoS Climate. - : Public Library of Science (PLoS). - 2767-3200. ; 2:1
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Tidskriftsartikel (refereegranskat)abstract
- Seagrass meadows are globally important blue carbon sinks. In northern cold-temperate regions, eelgrass (Zostera marina) is the dominant seagrass species, and although their sedimentary carbon stocks have been quantified across regions, information regarding the CO2 withdrawal capacity as carbon sinks remains scarce. Here we assessed the carbon (Corg) accumulation rates (CARs) and stocks as well as the organic matter sources in five seagrass meadows in the Gullmar Fjord area on the Swedish Skagerrak coast. We found that the mean (±SD) CAR was 14 ± 3 g Corg m-2 yr-1 over the last ~120–140 years (corresponding to a yearly uptake of 52.4 ± 12.6 g CO2 m-2). The carbon sink capacity is in line with other Z. marina areas but relatively low compared to other seagrass species and regions globally. About half of the sedimentary carbon accumulation (7.1 ± 3.3 g Corg m-2 yr-1) originated from macroalgae biomass, which highlights the importance of non-seagrass derived material for the carbon sink function of seagrass meadows in the area. The Corg stocks were similar among sites when comparing at a standardized depth of 50 cm (4.6–5.9 kg Corg m-2), but showed large variation when assessed for the total extent of the cores (ranging from 0.7 to 20.6 kg Corg m-2 for sediment depths of 11 to at least 149 cm). The low sediment accretion rates (1.18–1.86 mm yr-1) and the relatively thick sediment deposits (with a maximum of >150 cm of sediment depth) suggests that the carbon stocks have likely been accumulated for an extended period of time, and that the documented loss of seagrass meadows in the Swedish Skagerrak region and associated erosion of the sediment could potentially have offset centuries of carbon sequestration.
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| 3. |
- Löfgren, Sara E, et al.
(författare)
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Genetic association of miRNA-146a with systemic lupus erythematosus in Europeans through decreased expression of the gene
- 2012
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Ingår i: Genes and Immunity. - : Springer Science and Business Media LLC. - 1476-5470 .- 1466-4879. ; 13:3, s. 268-274
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Tidskriftsartikel (refereegranskat)abstract
- A recent genome-wide association study revealed a variant (rs2431697) in an intergenic region, between the pituitary tumor-transforming 1 (PTTG1) and microRNA (miR-146a) genes, associated with systemic lupus erythematosus (SLE) susceptibility. Here, we analyzed with a case-control design this variant and other candidate polymorphisms in this region together with expression analysis in order to clarify to which gene this association is related. The single-nucleotide polymorphisms (SNPs) rs2431697, rs2910164 and rs2277920 were genotyped by TaqMan assays in 1324 SLE patients and 1453 healthy controls of European ancestry. Genetic association was statistically analyzed using Unphased. Gene expression of PTTG1, the miRNAs miR-3142 and primary and mature forms of miR-146a in peripheral blood mononuclear cells (PBMCs) were assessed by quantitative real-time PCR. Of the three variants analyzed, only rs2431697 was genetically associated with SLE in Europeans. Gene expression analysis revealed that this SNP was not associated with PTTG1 expression levels, but with the microRNA-146a, where the risk allele correlates with lower expression of the miRNA. We replicated the genetic association of rs2341697 with SLE in a case-control study in Europeans and demonstrated that the risk allele of this SNP correlates with a downregulation of the miRNA 146a, potentially important in SLE etiology.
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| 4. |
- Hesselman, Susanne, 1973-, et al.
(författare)
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Abdominal adhesions in gynaecologic surgery after caesarean section : a longitudinal population-based register study.
- 2018
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Ingår i: British Journal of Obstetrics and Gynecology. - : Wiley. - 1470-0328 .- 1471-0528. ; 125:5, s. 597-603
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVE: The aim of the study was to evaluate the association between abdominal adhesions at the time of gynaecologic surgery and a history of caesarean delivery, and to investigate obstetric factors contributing to adhesion formation after caesarean section (CS).DESIGN: Longitudinal population-based register study.SETTING: Sweden.POPULATION: Women undergoing benign hysterectomy and/or adnexal surgery in Sweden, 2000-2014, with a previous delivery during 1973-2013 (n = 15 479).METHODS: Information about abdominal adhesions during gynaecological surgery, prior medical history, pregnancies and deliveries were retrieved from Swedish National Health and Quality registers.MAIN OUTCOME MEASURES: Adhesions.RESULTS: In women with previous CS, adhesions were present in 37%, compared with 10% of women with no previous CS [odds ratio (OR): 5.18, 95% confidence interval (CI): 4.70-5.71]. Adhesions increased with the number of caesarean sections: 32% after one CS; 42% after two CS and 59% after three or more CS (P < 0.001). Regardless of the number of CS, factors at CS such as age ≥35 years (aOR: 1.28, 95% CI: 1.05-1.55), body mass index (BMI) ≥30 [adjusted OR (aOR): 1.91, 95% CI: 1.49-2.45] and postpartum infection (aOR: 1.55, 95% CI: 1.05-2.30) increased the risk of adhesions.CONCLUSIONS: Presence of adhesions in abdominal gynaecological surgery is associated with women's personal history of caesarean delivery. The number of caesarean sections was the important predictor of adhesions; advanced age, obesity and postpartum infection further increased the incidence.TWEETABLE ABSTRACT: Repeat caesarean, age, obesity and infection increased the risk of pelvic adhesions after caesarean section.
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| 5. |
- Löfgren, Caroline E E, 1972, et al.
(författare)
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Effects of calcium, pH, and blockiness on kinetic rheological behavior and microstructure of HM pectin gels
- 2005
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Ingår i: Biomacromolecules. - : American Chemical Society (ACS). - 1525-7797 .- 1526-4602. ; 6:2, s. 646-652
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Tidskriftsartikel (refereegranskat)abstract
- The kinetic behavior during gel formation and the microstructure of 0.75% high methoxyl (HM) pectin gels in 60% sucrose have been investigated by oscillatory measurements and transmission electron microscopy for three comparable citrus pectin samples differing in their degree of blockiness (DB). Ca2+ addition at pH 3.0 resulted in faster gel formation and a lower storage modulus after 3 h for gels of the blockwise pectin A. For gels of the randomly esterified pectin B, the Ca2+ addition resulted in faster gel formation and a higher storage modulus at pH 3.0. At pH 3.5, both pectins A and B were reinforced by the addition of Ca2+. In the absence of Ca2+, the shortest gelation time was obtained for the sample with the highest DB. Microstructural characterization of the gel network, 4 and 20 h after gel preparation, showed no visible changes on a nanometer scale. The microstructure of pectins A and B without Ca2+ was similar, whereas the presence of Ca2+ in pectin A resulted in an inhomogeneous structure. © 2005 American Chemical Society.
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| 6. |
- Löfgren, Caroline E E, 1972
(författare)
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Microstructure and Gelation Behaviour of High Methoxyl and Low Methoxyl Pectin Gels and their Mixtures
- 2005
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The objective of this thesis was to explore the functional behaviour of high methoxyl (HM), low methoxyl (LM) and mixed HM/LM pectin gels of different chemical characteristics with emphasis on microstructure and kinetic rheological behaviour. The rheological properties and the structure of pectin gel networks were investigated for pectins under different sucrose, calcium and pH conditions by the means of oscillatory measurements and transmission electron microscopy (TEM).The gel microstructure of HM and LM pectin showed similar appearance at pH 3. Both HM and LM pectins formed open and aggregated network structures with many pores about ~ 500 nm in diameter. Mixed HM/LM pectin gels revealed different gel structures than the HM and LM pectin gels. The microstructure of the mixed HM/LM pectin gels was strongly affected by the presence of calcium.The kinetic behaviour during gel formation differed for HM and LM pectins. HM pectins does not require calcium ions for gel formation but this work showed that calcium has a profound effect on the kinetic behaviour and in some cases also the microstructure. Rapid gel formation was obtained for LM pectin under all investigated conditions. The methyl esters and amide groups play a decisive role for the functionality of pectins. This work also showed that the distribution of methyl esters has a bearing on the functionality of the gels, both in the absence and the presence of calcium.LM pectin gelation occurs at a wide range of pH values, at reduced sugar concentrations or no sugar at all. The gelling conditions are different at acidic and neutral pH values, and it was shown that the kinetic behaviour and the microstructure of LM pectin were dissimilar at pH 3 and pH 7. The gel microstructure of LM pectin was much denser at pH 7 than at pH 3. The structural variations could be a direct result of the differing kinetic behaviour under acidic and neutral conditions or a result of a conformational transition that is associated with a pH change.There is an increasing demand for low-sugar food products with similar texture properties as high-sugar products. Pectin mixtures are interesting candidates for replacing the consistency given by the presence of sucrose. A strong synergistic effect in rheological behaviour occurred for mixed HM/LM pectin gels in the presence of sucrose and calcium. A HM pectin gel could be replaced with a mixed HM/LM pectin gel of lower sugar content with maintained rheological behaviour. The kinetic rheological behaviour of the mixed gels was influenced by both HM and LM pectin gelation. Different gel formation behaviour of the mixed HM/LM pectin gels could be achieved depending on the degree of blockiness of the HM pectins.
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| 7. |
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| 8. |
- Löfgren, Sara E., et al.
(författare)
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A 3 '-Untranslated Region Variant Is Associated With Impaired Expression of CD226 in T and Natural Killer T Cells and Is Associated With Susceptibility to Systemic Lupus Erythematosus
- 2010
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Ingår i: Arthritis and Rheumatism. - : Wiley. - 0004-3591 .- 1529-0131. ; 62:11, s. 3404-3414
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Tidskriftsartikel (refereegranskat)abstract
- Objective. Costimulatory receptor CD226 plays an important role in T cell activation, differentiation, and cytotoxicity. This study was undertaken to investigate the genetic association of CD226 with susceptibility to systemic lupus erythematosus (SLE) and to assess the functional implications of this association. Methods. Twelve tag single-nucleotide polymorphisms (SNPs) in CD226 were typed in 1,163 SLE patients and 1,482 healthy control subjects from Europe or of European ancestry. Analyses of association were performed by single-marker Cochran-Mantel-Haenszel meta-analysis, followed by haplotype analysis. Gene expression was analyzed by quantitative real-time polymerase chain reaction analyses of RNA from peripheral blood mononuclear cells, and by fluorescence-activated cell sorter analysis. To study the functional impact of the associated variants, luciferase reporter constructs containing different portions of the 3'-untranslated region (3'-UTR) of the gene were prepared and used in transfection experiments. Results. A 3-variant haplotype, rs763361; rs34794968; rs727088 (ATC), in the last exon of CD226 was associated with SLE (P = 1.3 x 10(-4), odds ratio 1.24, 95% confidence interval 1.11-1.38). This risk haplotype correlated with low CD226 transcript expression and low CD226 protein levels on the surface of CD4+ and CD8+ T cells and natural killer T (NKT) cells. NK cells expressed high levels of CD226, but this expression was independent of the haplotype. Reporter assays with deletion constructs indicated that only the presence of rs727088 could account for the differences in the levels of luciferase transcripts. Conclusion. This study identified an association of CD226 with SLE in individuals of European ancestry. These data support the importance of the 3'-UTR SNP rs727088 in the regulation of CD226 transcription both in T cells and in NKT cells.
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| 9. |
- Löfgren, Sara E, et al.
(författare)
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Estrogen-dependent upregulation of IRF5 in human immune cells
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Objective: To contribute to the knowledge of the mechanisms behind the strong sex-biased prevalence of SLE, we investigated the role of estrogen on the expression of one of the strongest associated gene with SLE, the interferon regulatory factor 5 (IRF5), in human immune cells. Material and methods: IRF5, as well as IRF3, IRF4, IRF7 and IRF9 expression was measured in PBMCs, LCLs, monocytes and macrophages from both male and female origin. Cells were treated with different concentrations of estrogen and gene expression was measured by quantitative RT-PCR. Results: We found that the initial levels of IRF5 in PBMC were almost 2-fold higher in women than men, although not reaching statistical significance. After 12 h in culture the IRF5 levels became roughly equal in both sexes, and further stimulation with estrogen lead to up-regulation of IRF5 expression in both PBMCs and monocytes in both women and men. No difference was seen for IRF3, IRF4, IRF7 and IRF9 expression, and no gene was up-regulated in LCLs, upon estrogen treatment, regardless of the gender. Conclusions: We showed that in human PBMCs and monocytes from healthy individuals IRF5 expression can be regulated by exogenous estrogen. This feature might be specific to IRF5 since four other IRF genes tested did not show any up-regulation in these cells.
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| 10. |
- Löfgren, Sara E., et al.
(författare)
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Promoter Insertion/Deletion in the IRF5 Gene Is Highly Associated with Susceptibility to Systemic Lupus Erythematosus in Distinct Populations, But Exerts a Modest Effect on Gene Expression in Peripheral Blood Mononuclear Cells
- 2010
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Ingår i: Journal of Rheumatology. - : The Journal of Rheumatology. - 0315-162X .- 1499-2752. ; 37:3, s. 574-578
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Tidskriftsartikel (refereegranskat)abstract
- Objective. We examined the genetic association of the promoter insertion/deletion (indel) in IRF5 gene with systemic lupus erythematosus (SLE) in distinct populations and assessed its role in gene expression. Methods. Four IRF5 polymorphisms were genotyped in 1488 SLE patients and 1466 controls. Gene expression was analyzed by quantitative real-time PCR using RNA from peripheral blood mononuclear cells (PBMC). Results. The promoter indel and rs2070197 had independent genetic effects, which accounted for the association of rs2004640 and rs10954213. Gene expression analysis revealed that rs10954213 exerted the greatest influence on IRF5 transcript levels. Conclusion. We corroborated the association of the promoter indel with SLE in 5 different populations and revealed that rs10954213 is the main single-nucleotide polymorphism responsible for altered IRF5 expression in PBMC.
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