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- 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. |
- Pereira, Maria J., 1981-, et al.
(författare)
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CDKN2C expression in adipose tissue is reduced in type II diabetes and central obesity: impact on adipocyte differentiation and lipid storage?
- 2022
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Ingår i: Translational Research. - : Elsevier BV. - 1931-5244 .- 1878-1810. ; 242, s. 105-121
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Tidskriftsartikel (refereegranskat)abstract
- CDKN2C/p18 (Cyclin-Dependent Kinase Inhibitor 2C) is a cell growth regulator that controls cell cycle progression and has previously been associated with increased risk for type II diabetes (T2D) and reduced peripheral adipose tissue (AT) storage capacity. This study explored the role of CDKN2C in AT lipid and glucose metabolism in T2D. Expression of CDKN2C and other genes was analyzed by transcriptomics, or real-time PCR in subcutaneous AT (SAT) samples obtained from T2D and control subjects matched for sex, age and BMI and also in paired SAT and omental AT (OAT) samples. Functional studies included adipocyte glucose uptake and lipolysis rates. CRISPR/Cas9 CDKN2C gene knockdown was performed in human preadipocytes to assess adipogenesis. CDKN2C mRNA expression in SAT and OAT was reduced in T2D and obese subjects compared to controls. CDKN2C expression in SAT was inversely correlated with measures of hyperglycemia, insulin resistance and visceral adiposity and positively correlated with expression of genes in several metabolic pathways, including insulin signaling and fatty acid and carbohydrate metabolism. CDKN2C protein was mainly expressed in adipocytes compared to stromal vascular cells, and its gene and protein expression was up-regulated during adipocyte differentiation. Knockdown of CDKN2C did not affect the percentage of differentiating cells compared to wild type cultures. However, CDKN2C knockdown cultures had significantly lower expression of differentiation markers CEBPA, ADIPOQ and FASN and transiently reduced lipid accumulation per adipocyte during differentiation. Our findings suggest that adipose CDKN2C expression might be reduced as a consequence of insulin resistance and obesity, and this can further contribute to impairment of SAT lipid storage. © 2021 The Authors
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| 3. |
- Ahmed, Fozia, et al.
(författare)
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Role of Estrogen and Its Receptors in Adipose Tissue Glucose Metabolism in Pre- and Postmenopausal Women
- 2022
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Ingår i: Journal of Clinical Endocrinology and Metabolism. - : ENDOCRINE SOC. - 0021-972X .- 1945-7197. ; 107:5, s. E1879-E1889
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Tidskriftsartikel (refereegranskat)abstract
- Context: Reduced estrogen levels in postmenopausal women predispose them to metabolic side effects, including insulin resistance and type 2 diabetes; however, the cellular mechanisms are not well understood.Objective: This work aimed to study the expression of estrogen receptors in adipose tissue from pre- and postmenopausal women and the effects of estradiol (E2) on glucose uptake of adipocytes.Methods: Subcutaneous (SAT) and visceral adipose tissue (VAT) obtained from pre- and postmenopausal women (19-51 and 46-75 years old, respectively) were used to measure gene expression of ESR1 and ESR2. SAT tissue was incubated with E2, and glucose uptake and estrogen receptor levels were measured. Polymorphisms in ESR1 and ESR2 were addressed in public databases to identify single nucleotide polymorphisms associated with metabolic traits.Results: ESR2 expression was lower in pre- vs postmenopausal women, corresponding to lower ESR1:ESR2 gene expression ratio in postmenopausal women. In premenopausal women, the expression of ESR1 was higher in VAT than in SAT. In both pre- and postmenopausal women, ESR2 expression was lower in VAT than in SAT. In late, but not pre- or early postmenopausal women, E2 reduced glucose uptake and GLUT4 protein and increased expression of ESR2. ESR1 polymorphisms were associated with weight, body fat distribution, and total cholesterol, and ESR2 polymorphisms were associated with total cholesterol and triglyceride levels and with body fat percentage.Conclusion: E2 inhibits glucose utilization in human adipocytes in late postmenopausal women. Changes in glucose utilization over time since menopause may be explained by a lower ESR1:ESR2 ratio. This can have clinical implications on the timing of estrogen treatment in postmenopausal women.
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| 4. |
- 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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| 5. |
- Vranic, Milica, et al.
(författare)
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Subcutaneous adipose tissue dopamine D2 receptor expression is increased in prediabetes and T2D
- 2024
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Ingår i: Endocrine. - : Springer. - 1355-008X .- 1559-0100. ; 83
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Tidskriftsartikel (refereegranskat)abstract
- PurposeTo evaluate the dopaminergic signaling in human adipose tissue in the context of obesity and type 2 diabetes (T2D) and potential direct implications in adipose tissue metabolism.MethodsmRNA and protein expression of dopamine receptors D1 and D2 (DRD1 and DRD2) were determined in subcutaneous adipose tissue from subjects without or with T2D and with different body weight, and correlated with markers of obesity, hyperglycemia, and insulin resistance. Glucose uptake and lipolysis were measured in adipocytes ex vivo following short-term exposure to dopamine, DRD1 receptor agonist (SKF81297), or DRD2 receptor agonist (bromocriptine).ResultsDRD1 and DRD2 gene expression in subcutaneous adipose tissue correlated positively with clinical markers of insulin resistance (e.g. HOMA-IR, insulin, and triglycerides) and central obesity in subjects without T2D. Protein expression of DRD2 in subcutaneous adipose tissue, but not DRD1, is higher in subjects with impaired fasting glucose and T2D and correlated positively with hyperglycemia, HbA1c, and glucose AUC, independent of obesity status. DRD1 and DRD2 proteins were mainly expressed in adipocytes, compared to stromal vascular cells. Dopamine and dopaminergic agonists did not affect adipocyte glucose uptake ex vivo, but DRD1 and DRD2 agonist treatment inhibited isoproterenol-stimulated lipolysis.ConclusionThe results suggest that protein expression of DRD2 in subcutaneous adipose tissue is up-regulated with hyperglycemia and T2D. Whether DRD2 protein levels contribute to T2D development or occur as a secondary compensatory mechanism needs further investigation. Additionally, dopamine receptor agonists inhibit adipocyte beta-adrenergic stimulation of lipolysis, which might contribute to the beneficial effects in lipid metabolism as observed in patients taking bromocriptine.
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