| 1. |
- Boberg, Johanna, et al.
(författare)
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Nitrogen and Carbon Reallocation in Fungal Mycelia during Decomposition of Boreal Forest Litter
- 2014
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Ingår i: PLOS ONE. - : Public Library of Science. - 1932-6203. ; 9:3, s. e92897-
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Tidskriftsartikel (refereegranskat)abstract
- Boreal forests are characterized by spatially heterogeneous soils with low N availability. The decomposition of coniferous litter in these systems is primarily performed by basidiomycete fungi, which often form large mycelia with a well-developed capacity to reallocate resources spatially-an advantageous trait in heterogeneous environments. In axenic microcosm systems we tested whether fungi increase their biomass production by reallocating N between Pinus sylvestris (Scots pine) needles at different stages of decomposition. We estimated fungal biomass production by analysing the accumulation of the fungal cell wall compound chitin. Monospecific systems were compared with systems with interspecific interactions. We found that the fungi reallocated assimilated N and mycelial growth away from well-degraded litter towards fresh litter components. This redistribution was accompanied by reduced decomposition of older litter. Interconnection of substrates increased over-all fungal C use efficiency (i.e. the allocation of assimilated C to biomass rather than respiration), presumably by enabling fungal translocation of growth-limiting N to litter with higher C quality. Fungal connection between different substrates also restricted N-mineralization and production of dissolved organic N, suggesting that litter saprotrophs in boreal forest ecosystems primarily act to redistribute rather than release N. This spatial integration of different resource qualities was hindered by interspecific interactions, in which litters of contrasting quality were colonised by two different basidiomycete species. The experiments provide a detailed picture of how resource reallocation in two decomposer fungi leads to a more efficient utilisation of spatially separated resources under N-limitation. From an ecosystem point of view, such economic fungal behaviour could potentially contribute to organic matter accumulation in the litter layers of boreal forests.
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| 2. |
- Abraham, Mark James, et al.
(författare)
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Sharing Data from Molecular Simulations
- 2019
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Ingår i: Journal of Chemical Information and Modeling. - : AMER CHEMICAL SOC. - 1549-9596 .- 1549-960X. ; 59:10, s. 4093-4099
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Tidskriftsartikel (refereegranskat)abstract
- Given the need for modern researchers to produce open, reproducible scientific output, the lack of standards and best practices for sharing data and workflows used to produce and analyze molecular dynamics (MD) simulations has become an important issue in the field. There are now multiple well-established packages to perform molecular dynamics simulations, often highly tuned for exploiting specific classes of hardware, each with strong communities surrounding them, but with very limited interoperability/transferability options. Thus, the choice of the software package often dictates the workflow for both simulation production and analysis. The level of detail in documenting the workflows and analysis code varies greatly in published work, hindering reproducibility of the reported results and the ability for other researchers to build on these studies. An increasing number of researchers are motivated to make their data available, but many challenges remain in order to effectively share and reuse simulation data. To discuss these and other issues related to best practices in the field in general, we organized a workshop in November 2018 (https://bioexcel.eu/events/workshop-on-sharing-data-from-molecular-simulations/). Here, we present a brief overview of this workshop and topics discussed. We hope this effort will spark further conversation in the MD community to pave the way toward more open, interoperable, and reproducible outputs coming from research studies using MD simulations.
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| 3. |
- Boberg, Johanna, et al.
(författare)
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Fungal C translocation restricts N-mineralization in heterogeneous environments
- 2010
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Ingår i: Functional Ecology. - : Wiley. - 0269-8463 .- 1365-2435. ; 24, s. 454-459
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Tidskriftsartikel (refereegranskat)abstract
- P>1. In forest soils, fungi generally dominate the decomposer community, but their specific, filamentous physiology is often not recognized in nitrogen (N) cycling models. Many litter degrading fungi form large mycelia and have a well-developed capacity to translocate resources within their mycelia. Fungi may thus connect substrates that differ with respect to carbon (C) and nitrogen (N) availability and, thereby, overcome local resource limitation through translocation.2. Here we test whether the ability of fungi to translocate carbohydrates within their mycelia prevents local C limitation in a low C:N ratio substrate, thereby reducing N mineralization. The capacity of fungi to translocate N to a high C:N ratio substrate in order to increase the decomposition, was also assessed. Two litter decomposing fungi, Marasmius androsaceus and Mycena epipterygia were grown in axenic laboratory microcosms containing spatially separated substrates: pine needles (C:N = 135) and glycine (C:N = 2).3. In the absence of needles both fungi mineralized the glycine N. When connecting the two substrates, both fungi were able to overcome local C-deficiency on the glycine medium by translocating carbohydrates from the needles. In the presence of needles, N mineralization from glycine was negligible, although the glycine was utilized. Only trace amounts of N were translocated from glycine to the needles.4. A basic assumption of N cycling models is that substrates of different qualities decompose in an independent manner. Our observations imply that this assumption may be violated in heterogenic environments dominated by fungi.
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| 4. |
- Kibugu, James, et al.
(författare)
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Improved Sample Selection and Preparation Methods for Sampling Plans Used to Facilitate Rapid and Reliable Estimation of Aflatoxin in Chicken Feed
- 2021
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Ingår i: Toxins. - : MDPI. - 2072-6651. ; 13:3
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Tidskriftsartikel (refereegranskat)abstract
- Aflatoxin B1 (AFB1), a toxic fungal metabolite associated with human and animal diseases, is a natural contaminant encountered in agricultural commodities, food and feed. Heterogeneity of AFB1 makes risk estimation a challenge. To overcome this, novel sample selection, preparation and extraction steps were designed for representative sampling of chicken feed. Accuracy, precision, limits of detection and quantification, linearity, robustness and ruggedness were used as performance criteria to validate this modification and Horwitz function for evaluating precision. A modified sampling protocol that ensured representativeness is documented, including sample selection, sampling tools, random procedures, minimum size of field-collected aggregate samples (primary sampling), procedures for mass reduction to 2 kg laboratory (secondary sampling), 25 g test portion (tertiary sampling) and 1.3 g analytical samples (quaternary sampling). The improved coning and quartering procedure described herein (for secondary and tertiary sampling) has acceptable precision, with a Horwitz ratio (HorRat = 0.3) suitable for splitting of 25 g feed aliquots from laboratory samples (tertiary sampling). The water slurring innovation (quaternary sampling) increased aflatoxin extraction efficiency to 95.1% through reduction of both bias (-4.95) and variability of recovery (1.2-1.4) and improved both intra-laboratory precision (HorRat = 1.2-1.5) and within-laboratory reproducibility (HorRat = 0.9-1.3). Optimal extraction conditions are documented. The improved procedure showed satisfactory performance, good field applicability and reduced sample analysis turnaround time.
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| 5. |
- Sténs, Anna, 1976-, et al.
(författare)
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From ecological knowledge to conservation policy : a case study on green tree retention and continuous-cover forestry in Sweden
- 2019
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Ingår i: Biodiversity and Conservation. - : Springer. - 0960-3115 .- 1572-9710. ; 28:13, s. 3547-3574
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Tidskriftsartikel (refereegranskat)abstract
- The extent to which scientific knowledge translates into practice is a pervasive question. We analysed to what extent and how ecological scientists gave input to policy for two approaches advocated for promoting forest biodiversity in production forests in Sweden: green-tree retention (GTR) and continuous-cover forestry (CCF). GTR was introduced into forest policy in the 1970s and became widely implemented in the 1990s. Ecological scientists took part in the policy process by providing expert opinions, educational activities and as lobbyists, long before research confirming the positive effects of GTR on biodiversity was produced. In contrast, CCF was essentially banned in forest legislation in 1979. In the 1990s, policy implicitly opened up for CCF implementation, but CCF still remains largely a rare silvicultural outlier. Scientific publications addressing CCF appeared earlier than GTR studies, but with less focus on the effects on biodiversity. Ecological scientists promoted CCF in certain areas, but knowledge from other disciplines and other socio-political factors appear to have been more important than ecological arguments in the case of CCF. The wide uptake of GTR was enhanced by its consistency with the silvicultural knowledge and normative values that forest managers had adopted for almost a century, whereas CCF challenged those ideas. Public pressure and institutional requirements were also key to GTR implementation but were not in place for CCF. Thus, scientific ecological knowledge may play an important role for policy uptake and development, but knowledge from other research disciplines and socio-political factors are also important.
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| 6. |
- Begum, Ruhena, et al.
(författare)
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Heavy metal contamination in retailed food in Bangladesh : a dietary public health risk assessment
- 2023
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Ingår i: Frontiers in Sustainable Food Systems. - : Frontiers Media S.A.. - 2571-581X. ; 7
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Tidskriftsartikel (refereegranskat)abstract
- IntroductionContamination with heavy and toxic metals along the food value chain is a public health concern in Bangladesh. MethodsIn this study, 608 fish and chicken samples from traditional and modern retail outlets in urban, peri-urban, and rural areas were collected and analyzed for chromium (Cr), cadmium (Cd), and lead (Pb) contamination, using atomic absorption spectrometry method. The daily intake, target hazard quotient and the target carcinogenic risk (for lead only) as a result of fish and chicken consumption was calculated based on mean results, and by Monte Carlo simulation in @Risk with 100,000 iterations (quantitative risk assessment). ResultsCr and Cd were detected in 80-86% of both chicken meat and fish samples, while Pb positivity found in chicken meat and fish was 54.9 and 23.3%, respectively. The mean concentration (+/- SD) of Cr, Cd, and Pb in chicken meat were 0.66 +/- 0.93, 0.02 +/- 0.03, and 0.09 +/- 0.10 mg/kg, respectively; and in fish were 0.49 +/- 0.62, 0.02 +/- 0.03, and 0.06 +/- 0.09 mg/kg, respectively. The estimated daily intakes of Cr, Cd, and Pb from chicken and fish were lower than the maximum tolerable daily intake in all studied areas. In addition, the target carcinogenic risk for Pb in chicken was lower than the negligible range, which indicated the risk of cancer due to exposure to Pb through chicken meat and fish consumption was very low. DiscussionThe present study concludes that consumption of chicken meat and fish in Bangladesh, currently at very low levels, is unlikely to constitute a major health risk for humans in respect to these metals. However, continuous market surveillance for heavy metals in food stuff is recommended, especially since consumers may increase their meat intake.
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| 7. |
- Boberg, Johanna, et al.
(författare)
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Nitrogen availability affects saprotrophic basidiomycetes decomposing pine needles in a long term laboratory study
- 2011
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Ingår i: Fungal Ecology. - : Elsevier BV. - 1754-5048 .- 1878-0083. ; 4, s. 408-416
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Tidskriftsartikel (refereegranskat)abstract
- Fungi, especially basidiomycetous litter decomposers, are pivotal to the turnover of soil organic matter in forest soils. Many litter decomposing fungi have a well-developed capacity to translocate resources in their mycelia, a feature that may significantly affect carbon (C) and nitrogen (N) dynamics in decomposing litter. In an eight-month long laboratory study we investigated how the external availability of N affected the decomposition of Scots pine needles, fungal biomass production, N retention and N-mineralization by two litter decomposing fungi - Marasmius androsaceus and Mycena epipterygia. Glycine additions had a general, positive effect on fungal biomass production and increased accumulated needle mass loss after 8 months, suggesting that low N availability may limit fungal growth and activity in decomposing pine litter. Changes in the needle N pool reflected the dynamics of the fungal mycelium. During late decomposition stages, redistribution of mycelium and N out from the decomposed needles was observed for M. epipterygia, suggesting autophagous self degradation. (C) 2011 Elsevier Ltd and The British Mycological Society. All rights reserved.
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| 8. |
- Connolly-Andersen, Anne-Marie, et al.
(författare)
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Increased Thrombopoiesis and Platelet Activation in Hantavirus-Infected Patients
- 2015
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Ingår i: Journal of Infectious Diseases. - : Oxford University Press. - 0022-1899 .- 1537-6613. ; 212:7, s. 1061-1069
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Tidskriftsartikel (refereegranskat)abstract
- Background. Thrombocytopenia is a common finding during viral hemorrhagic fever, which includes hemorrhagic fever with renal syndrome (HFRS). The 2 main causes for thrombocytopenia are impaired thrombopoiesis and/or increased peripheral destruction of platelets. In addition, there is an increased intravascular coagulation risk during HFRS, which could be due to platelet activation. Methods. Thrombopoiesis was determined by quantification of platelet counts, thrombopoietin, immature platelet fraction, and mean platelet volume during HFRS. The in vivo platelet activation was determined by quantification of soluble P-selectin (sP-selectin) and glycoprotein VI (sGPVI). The function of circulating platelets was determined by ex vivo stimulation followed by flow cytometry analysis of platelet surface-bound fibrinogen and P-selectin exposure. Intravascular coagulation during disease was determined by scoring for disseminated intravascular coagulation (DIC) and recording thromboembolic complications. Results. The levels of thrombopoietin, immature platelet fraction, and mean platelet volume all indicate increased thrombopoiesis during HFRS. Circulating platelets had reduced ex vivo function during disease compared to follow-up. Most interestingly, we observed significantly increased in vivo platelet activation in HFRS patients with intravascular coagulation (DIC and thromboembolic complications) as shown by sP-selectin and sGPVI levels. Conclusions. HFRS patients have increased thrombopoiesis and platelet activation, which contributes to intravascular coagulation.
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| 9. |
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| 10. |
- Gill, J. P. S., et al.
(författare)
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Pesticide Residues in Peri-Urban Bovine Milk from India and Risk Assessment : A Multicenter Study
- 2020
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Ingår i: Scientific Reports. - : NATURE PUBLISHING GROUP. - 2045-2322. ; 10:1
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Tidskriftsartikel (refereegranskat)abstract
- Pesticides residue poses serious concerns to human health. The present study was carried out to determine the pesticide residues of peri-urban bovine milk (n=1183) from five different sites (Bangalore, Bhubaneswar, Guwahati, Ludhiana and Udaipur) in India and dietary exposure risk assessment to adults and children. Pesticide residues were estimated using gas chromatography with flame thermionic and electron capture detectors followed by confirmation on gas chromatography-mass spectrometer. The results noticed the contamination of milk with hexachlorocyclohexane (HCH), dichloro-diphenyl trichloroethane (DDT), endosulfan, cypermethrin, cyhalothrin, permethrin, chlorpyrifos, ethion and profenophos pesticides. The residue levels in some of the milk samples were observed to be higher than the respective maximum residue limits (MRLs) for pesticide. Milk samples contamination was found highest in Bhubaneswar (11.2%) followed by Bangalore (9.3%), Ludhiana (6.9%), Udaipur (6.4%) and Guwahati (6.3%). The dietary risk assessment of pesticides under two scenarios i.e. lower-bound scenario (LB) and upper-bound (UB) revealed that daily intake of pesticides was substantially below the prescribed acceptable daily intake except for fipronil in children at UB. The non-cancer risk by estimation of hazard index (HI) was found to be below the target value of one in adults at all five sites in India. However, for children at the UB level, the HI for lindane, DDT and ethion exceeded the value of one in Ludhiana and Udaipur. Cancer risk for adults was found to be in the recommended range of United States environment protection agency (USEPA), while it exceeded the USEPA values for children.
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