| 1. |
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| 2. |
- Vestergård, Mette, et al.
(författare)
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Enhanced priming of old, not new soil carbon at elevated atmospheric CO2
- 2016
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Ingår i: Soil Biology and Biochemistry. - : Elsevier BV. - 0038-0717. ; 100, s. 140-148
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Tidskriftsartikel (refereegranskat)abstract
- Rising atmospheric CO2 concentrations accompanied by global warming and altered precipitation patterns calls for assessment of long-term effects of these global changes on carbon (C) dynamics in terrestrial ecosystems, as changes in net C exchange between soil and atmosphere will impact the atmospheric CO2 concentration profoundly. In many ecosystems, including the heath/grassland system studied here, increased plant production at elevated CO2 increase fresh C input from litter and root exudates to the soil and concurrently decrease soil N availability. Supply of labile C to the soil may accelerate the decomposition of soil organic C (SOC), a phenomenon termed 'the priming effect', and the priming effect is most pronounced at low soil N availability. Hence, we hypothesized that priming of SOC decomposition in response to labile C addition would increase in soil exposed to long-term elevated CO2 exposure. Further, we hypothesized that long-term warming would enhance SOC priming rates, whereas drought would decrease the priming response. We incubated soil from a long-term, full-factorial climate change field experiment, with the factors elevated atmospheric CO2 concentration, warming and prolonged summer drought with either labile C (sucrose) or water to assess the impact of labile C on SOC dynamics. We used sucrose with a 13C/12C signature that is distinct from that of the native SOC, which allowed us to assess the contribution of these two C sources to the CO2 evolved. Sucrose induced priming of SOC, and the priming response was higher in soil exposed to long-term elevated CO2 treatment. Drought tended to decrease the priming response, whereas long-term warming did not affect the level of priming significantly. We were also able to assess whether SOC-derived primed C in elevated CO2 soil was assimilated before or after the initiation of the CO2 treatment 8 years prior to sampling, because CO2 concentrations were raised by fumigating the experimental plots with pure CO2 that was 13C-depleted compared to ambient CO2. Surprisingly, we conclude that sucrose addition primed decomposition of relatively old SOC fractions, i.e. SOC assimilated more than 8 years before sampling.
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| 3. |
- Wang, Tao, et al.
(författare)
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Mineral surface-reactive metabolites secreted during fungal decomposition contribute to the formation of soil organic matter
- 2017
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Ingår i: Environmental Microbiology. - : Wiley. - 1462-2912. ; 19:12, s. 5117-5129
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Tidskriftsartikel (refereegranskat)abstract
- Soil organic matter (SOM) constitutes the largest terrestrial C pool. An emerging, untested, view is that oxidation and depolymerization of SOM by microorganisms promote the formation of SOM-mineral associations that is critical for SOM stabilization. To test this hypothesis, we performed laboratory-scale experiments involving one ectomycorrhizal and one saprotrophic fungus that represent the two major functional groups of microbial decomposers in the boreal forest soils. Fungal decomposition enhanced the retention of SOM on goethite, partly because of oxidative modifications of organic matter (OM) by the fungi. Moreover, both fungi secreted substantial amounts (> 10% new biomass C) of aromatic metabolites that also contributed to an enhanced mineral retention of OM. Our study demonstrates that soil fungi can form mineral-stabilized SOM not only by oxidative conversion of the SOM but also by synthesizing mineral surface-reactive metabolites. Metabolites produced by fungal decomposers can play a yet overlooked role in the formation and stabilization of SOM.
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| 4. |
- Ahlberg, Per, et al.
(författare)
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Phosphatised olenid trilobites and associated fauna from the Upper Cambrian of Vastergotland, Sweden
- 2005
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Ingår i: Acta Palaeontologica Polonica. - 0567-7920. ; 50:3, s. 429-440
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Tidskriftsartikel (refereegranskat)abstract
- Secondarily phosphatised olenid trilobites from organic-rich limestones (orsten) in the Furongian (Upper Cambrian) of Vastergotland, south-central Sweden, are described and illustrated. All trilobites originate from the Peltura scarabaeoides Zone and were collected on the western slope of Kinnekulle. Only the dorsal exoskeletons have become secondarily phosphatised, and the ventral appendages are not preserved. Yet the material is otherwise remarkably well preserved and reveals the morphology of the olenid trilobites in greater detail than hitherto known. Species belonging to the genera Ctenopyge, Sphaerophthalmus, Parabolina, and Peltura are identified, and several juvenile specimens are present in the material. The material is disarticulated and fragmentary, and it has only been possible to identify a few specimens to species level. In addition to chaetognaths and conodonts, the trilobites are associated with pelmatozoan columnals, a possible camaroid, and fossils of uncertain affinities. These fossils, along with a probable conulariid fragment from the Peltura minor Zone, are also described and discussed. The presence of a benthic fauna of pelmatozoans, and possible conulariids and camaroids, indicates that at least parts of the Peltura zones were deposited during dysoxic rather than anoxic periods. Moreover, the sea floor must have been firm enough to allow colonisation by sessile organisms.
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| 5. |
- Bengtson, Annika, et al.
(författare)
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Evolution and diversification related to rainfall regimes : diversification patterns in the South African genus Metalasia (Asteraceae-Gnaphalieae)
- 2015
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Ingår i: Journal of Biogeography. - : Wiley. - 0305-0270 .- 1365-2699. ; 42:1, s. 121-131
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Tidskriftsartikel (refereegranskat)abstract
- AimThe Cape region is known for its exceptional species richness, although much remains unknown regarding the appearance of the modern Cape flora. One explanation is that floral diversification was influenced by the establishment of winter rainfall/summer arid conditions hypothesized to have occurred towards the end of the Miocene. We studied the evolution and diversification of the plant genus Metalasia (Asteraceae-Gnaphalieae), with the aim of testing whether radiation patterns may have been influenced by the climatic changes. LocationSouth Africa, with emphasis on the south-west. MethodsThe radiation of Metalasia was investigated using two approaches: a species diffusion approach, which estimated the ancestral areas by means of a relaxed random walk while sampling from extant distributions; and a discrete approach, in which distributions were defined according to the phytogeographical centres of the Cape region. Secondarily derived clock rates from an earlier Gnaphalieae study were used for calibration purposes. ResultsOur analyses date Metalasia to approximately 6.9Ma, after the Miocene-Pliocene boundary and the establishment of the winter rainfall/summer arid conditions. Metalasia consists of two sister clades: Clade A and Clade B. Clade B, which is endemic to the winter rainfall area, is estimated to have diversified c. 6.4Ma, whereas Clade A, with a main distribution in the all-year rainfall area, is considerably younger, with a crown group age estimated to 3.3Ma. Diversification rates suggest an early rapid speciation, with rates decreasing through time both for Metalasia and for clades A and B separately. Ancestral area estimations show a possible scenario for the radiation of Metalasia to its current diversity and distribution, with no conflict between results inferred from diffusion or discrete methods. Main conclusionsThe diversification of Metalasia is estimated to have begun after the establishment of the winter rainfall/summer arid conditions, consistent with its radiation having been influenced by changes in the climatic regime.
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| 6. |
- Bengtson, Annika, et al.
(författare)
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Phylogeny and evolution of the South African genus Metalasia (Asteraceae-Gnaphalieae) inferred from molecular and morphological data
- 2014
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Ingår i: Botanical journal of the Linnean Society. - : Oxford University Press (OUP). - 0024-4074 .- 1095-8339. ; 174:2, s. 173-198
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Tidskriftsartikel (refereegranskat)abstract
- Metalasia is a genus in tribe Gnaphalieae (Asteraceae), endemic to South Africa and with its main distribution in the Cape Floristic Region. The genus comprises 57 species and, with a number of closely related genera, it constitutes the Metalasia clade'. A species-level phylogenetic analysis is presented, based on DNA sequences from two nuclear (internal and external transcribed spacer: ITS, ETS) and two plastid (psbA-trnH, trnL-trnF) regions together with morphological data. Analyses combining molecular and morphological data attempt not only to resolve species interrelationships, but also to detect patterns in character evolution. Phylogenetic analyses corroborate our earlier study and demonstrate that Metalasia is formed of two equally sized, well-supported sister groups, one of which is characterized by papillose cypselas. The results differ greatly from earlier hypotheses based on morphology alone, as few morphological characters support the phylogenetic patterns obtained. The two clades of Metalasia do, however, appear to differ in distribution, corresponding to the different rainfall regimes of South Africa. Analyses show a few taxa to be problematic; one example is the widely distributed M.densa which appears to be an intricate species complex.
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| 7. |
- Bengtson, Annika, et al.
(författare)
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PHYLOGENY AND GENERIC DELIMITATION OF THE METALASIA CLADE (ASTERACEAE-GNAPHALIEAE)
- 2011
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Ingår i: International journal of plant sciences. - : University of Chicago Press. - 1058-5893 .- 1537-5315. ; 172:8, s. 1067-1075
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Tidskriftsartikel (refereegranskat)abstract
- The Metalasia clade, which consists of the genus Metalasia and a number of much smaller satellite genera, is a South African group in the tribe Gnaphalieae (Asteraceae). This study scrutinizes the phylogenetic relationships of the Metalasia clade by means of chloroplast (trnL-trnF, psbA-trnH) and nuclear (external transcribed spacer, internal transcribed spacer) sequence data. The Metalasia clade is confirmed to be a monophyletic group, and the phylogenetic positions of the included genera are determined. The genus Metalasia may be monophyletic if the monotypic Planea is included, but the node has very poor support and further studies are needed. The Metalasia species fall into two well-supported groups, distinguishing the members of Karis's Metalasia densa group from the others. Lachnospermum is shown to be monophyletic and is placed as a possible sister group to Metalasia. Phaenocoma is placed as sister to the branch consisting of Metalasia and Lachnospermum. Calotesta, Hydroidea, and Atrichantha form a clade, with the monotypic Dolichothrix as their sister group.
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| 8. |
- Bengtson, Annika, 1982-
(författare)
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Systematics and biogeography of the South African Metalasia clade (Asteraceae-Gnaphalieae)
- 2014
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The Metalasia clade (Asteraceae–Gnaphalieae) consisting of the genera Metalasia, Atrichantha, Calotesta, Dolichothrix, Hydroidea, Lachnospermum, Phaenocoma, and Planea is endemic to South Africa with a main distribution within the Cape Floristic Region (CFR), a region known for its remarkable botanical diversity.The monophyly of the Metalasia clade, the relationships of its genera, and the circumscription of these as well as their position within the tribe Gnaphalieae is investigated using molecular data. The study confirms the Metalasia clade to be a monophyletic group, untangling the relationships between the included genera.Five new Metalasia species have been described since the latest revision of the genus, three of which are described in the present work. An updated key to all 57 species of the genus is also provided.A phylogenetic study of the genus Metalasia, including all 57 species, based on a combination of morphological and molecular data shows that Metalasia consists of two sister clades, Clade A and Clade B, morphologically separated by the papillose cypselas of Clade A. Metalasia is, however, not supported as monophyletic, and Lachnospermum is placed together with the Metalasia species of Clade B. Further, the monotypic Planea, originally described as Metalasia schlechteri, is placed well within Clade B.A biogeographical study reveals Metalasia to have evolved in the CFR around 6.9 Ma. Ancestral area estimations present a possible scenario for the radiation of Metalasia and show a difference between Clade A and B, correlated to the different rainfall regimes of southern Africa. The results show that Clade B began to diversify around 6.4 Ma in the winter rainfall area, whereas the diversification of the Clade A crown group, which is estimated to only 3.3 Ma, was initiated in the all-year rainfall area.
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| 9. |
- Bengtson, Annika, et al.
(författare)
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Three new species of metalasia (asteraceae gnaphalieae) from the western cape and an updated key to the genus
- 2013
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Ingår i: South African Journal of Botany. - : Elsevier BV. - 0254-6299 .- 1727-9321. ; 84, s. 72-82
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Tidskriftsartikel (refereegranskat)abstract
- Three new species of Metalasia from the Western Cape of South Africa are described; Metalasia tristis A.Bengtson & P.O.Karis, a small shrublet from the Groot Winterhoek Mountains, and Metalasia formosa A.Bengtson & P.O.Karis and Metalasia eburnea A.Bengtson & P.O.Karis both found in the Langeberg Mountains. The morphology and relationships of the three new species are discussed, and an updated key to the genus is provided.
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| 10. |
- Bengtson, Per, et al.
(författare)
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Archaeal abundance across a pH gradient in an arable soil and its relationship with bacterial and fungal growth rates.
- 2012
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Ingår i: Applied and Environmental Microbiology. - 0099-2240. ; 78:16, s. 5906-5911
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Tidskriftsartikel (refereegranskat)abstract
- Soil pH is one of the most influential factors for the composition of bacterial and fungal communities, but the influence of soil pH on the distribution and composition of soil archaeal communities has yet to be systematically addressed. The primary aim of this study was to determine how total archaeal abundance (qPCR based estimates of 16S rRNA gene copy numbers) is related to soil pH across a pH gradient (pH 4.0-8.3). Secondarily, we wanted to assess how archaeal abundance related to bacterial and fungal growth rates across the same pH gradient. We identified two distinct and opposite effects of pH on the archaeal abundance. In the lowest pH range (pH 4.0-4.7) the abundance of archaea did not seem to respond to pH. Above this pH range there was a sharp, almost 4-fold, decrease in archaeal abundance, reaching a minimum at pH 5.1-5.2. The low archaeal abundance of archaeal 16S rRNA gene copies at this pH then sharply increased almost 150-fold with pH, resulting in an increase in the ratio between archaeal and bacterial copy numbers from a minimum of 0.002 to more than 0.07 at pH 8. The non-uniform archaeal response to pH could reflect variation in the archaeal community composition along the gradient, with some archaea adapted to acidic conditions, and others to neutral to slightly alkaline conditions. This suggestion is reinforced by observations of contrasting outcomes of the (competitive) interactions between archaea, bacteria and fungi towards the lower and higher ends of the examined pH gradient.
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| 11. |
- Bengtson, Per, et al.
(författare)
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Bacterial immobilization and remineralization of N at different growth rates and N concentrations
- 2005
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Ingår i: FEMS Microbiology Ecology. - : Oxford University Press (OUP). - 1574-6941 .- 0168-6496. ; 54:1, s. 13-19
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Tidskriftsartikel (refereegranskat)abstract
- An experiment was designed to resolve two largely unaddressed questions about the turnover of N in soils. One is the influence of microbial growth rate on mobilization and remineralization of cellular N. The other is to what extent heterotrophic immobilization of NO3- is controlled by the soil concentration of NH4+. Bacteria were extracted from a deciduous forest soil and inoculated into an aqueous medium. Various N pool dilution/enrichment experiments were carried out to: (1) calculate the gross N immobilization and remineralization rates; (2) investigate their dependence on NH4+ and NO3- concentrations; (3) establish the microbial preference for NH4+ and NO3- depending on the NH4+/NO3- concentration ratio. Remineralization of microbial N occurred mainly at high growth rates and NH4+ concentrations. There was a positive correlation between NH4+ immobilization and remineralization rates, and intracellular recycling of N seemed to be an efficient way for bacteria to withstand low inorganic N concentrations. Thus, extensive remineralization of microbial N is likely to occur only when environmental conditions promote high growth rates. The results support previous observations of high NO3- immobilization rates, especially at low NH4+ concentrations, but NO3- was also immobilized at high NH4 concentrations. The latter can be understood if part of the microbial community has a preference for NO3- over NH4+ (c) 2005 Federation of European Microbiological Societies. Published by Elsevier B.V. All rights reserved.
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| 12. |
- Bengtson, Per
(författare)
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Carbohydrate dependent adhesion of leukocytes and the role of fucosyltransferase VII
- 2003
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Galectins, E-and P-selectins are carbohydrate-binding proteins that are up regulated at inflammatory lesions. Selectins expressed ou the activated endothelium mediate transient binding to leukocyte ligands that require sequential action of α 2,3-sialyltransferases and a 1,3-fucosyltransferases. ln leukocytes α1,3 fucosyltransferase VII adds fucose to α 2,3- sialylated lactosarnine acceptors in the final step of the biosynthesis of the selectin binding epitope sialyl Lewis x.The finding of low sialyl Lewis x expression in polymorphonuclear leukocytes from a patient with ulcerative colitis led to the discovery of a missense mutation (G329A) in the human gene coding for α1,3 fucosyltransferase VII, FUT7. Studies including enzymatic and immunochemical analysis oftransfected cell lines and isolated polymorphonuclear leukocytes from patients confirmed that this mutation impair the ability of α1,3 fucosyltransferase VII to synthesize sialyl Lewis x. The frequency of the mutation were measured in a mixed Swedish population and found to be -1 %. One individual carrying the FUT7-G329A mutation homozygously was identified. This individual suffered from ulcer disease, noninsulin-dependent diabetes, osteoporosis, spondyloarthrosis, and Sjögren's syndrome, but the relationship between disease and the mutation is not established.Studies using an in vitro flow chamber assay showed that transfected B-lymphoma cells and Epstein-Barr virus transformed B cells only transcribing FUT7-G329A were not able to interact with E-selectin during flow whereas polymorphonuclear leukocytes from the FUT7-G329A homozygous individual interacted well with both P- and E selectin during flow. The mRNA level of the fucosyltransferase IV coding gene, FUT4, was found to be elevated in the homozygous individual, which resulted in elevated levels ofthe CD65s epitope. However, transfected B-lymphoma cells and Epstein- Barr virus transformed cells did not show a similar elevation of FUT4 mRNA. In in vitro studies galectin-1 and- 3 were observed to be able to recruit polymorphonuclear leukocytes during flow. This thesis gives further insight into the molecular mechanisms leading to carbohydrate dependent dynamic adhesion between polymorphonuclear leukocytes and lectins during inflammation.
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| 13. |
- Bengtson, Per, 1971-, et al.
(författare)
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Characterization of EBV-transformed B-cells established from an individual homozygously mutated (G329A) in the FUT7 alpha1,3-fucosyltransferase gene
- 2005
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Ingår i: Scand J Immunol. - : Wiley. ; 62:3, s. 251-8
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Tidskriftsartikel (refereegranskat)abstract
- The alpha1,3-fucosyltransferase VII (Fuc-TVII) is involved in the biosynthesis of E- and P-selectin ligands such as sialyl Lewis x (SLe(x)) on human leukocytes. Recently, individuals were characterized carrying a missense mutation (G329A; Arg110-Gln) in the FUT7 gene encoding this enzyme. The mutated FUT7 construct produced a Fuc-TVII enzyme with impaired activity compared with the wildtype enzyme. Polymorphonuclear granulocytes from an individual carrying this mutation homozygously also showed a reduced expression of SLe(x). In the present study, we have established Epstein-Barr virus-transformed B-cell lines from this individual (SIGN) and from an individual not carrying the mutation (IWO). The cell lines were confirmed to be of B-cell origin by flow cytometry analysis. IWO cells interacted with E-selectin in an in vitro flow chamber analysis whereas SIGN cell did not. However, when SIGN cell was transiently transfected with wildtype FUT7 cDNA, interaction with E-selectin could be restored. Cell surface expression of the SLe(x)-related epitopes recognized by antibodies CSLEX-1, KM-93 and HECA-452 was elevated on IWO cells compared with that on SIGN cells, consistent with a role of these antigens in E-selectin recognition. These cell lines will be useful in further characterization of E-selectin ligands and encourage further studies on the consequences of the FUT7-G329A mutation in vivo.
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| 14. |
- Bengtson, Per, et al.
(författare)
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EBV-transformed B-cells from an individual homozygously mutated (G329A) in FUT7 do not roll on E-selectin
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- The α1,3 fucosyltransferase VII (Fuc-TVII) is involved in the biosynthesis of E- and P-selectin ligands such as sialyl Lewis x on human leukocytes. Recently, individuals were characterized carrying a missense mutation (G329A; Arg110-Gln) in the FUT7 gene encoding this enzyme. The mutated FUT7 construct was not able to produce an active Fuc-TVII enzyme in transfection studies and polymorphonuclear granulocytes from an individual carrying the mutation homozygously showed severely reduced expression of sialyl Lewis x. In the present study we have established Epstein-Barr virus transformed B-celllines from this individual (SIGN) and from an individual not carrying the mutation (IWO). The cell lines were confirmed to be of B-cell origin by flow cytometry analysis. IWO cells interacted with E-selectin in an in vitro flow chamber analysis whereas SIGN cell did not. However, when SIGN cell were transfected with wild type FUT7 cDNA interaction with E-selectin could be restored. Cell surface expression of the sLex related epitopes recognized by antibodies CSLEX-1, KM-93 and HECA-452 was elevated on IWO cells compared to SIGN cells, consistent with a role of these antigens in E-selectin recognition. Despite high expression of PSGL-1 neither of the cell lines interacted with P-selectin under flow. These cell lines may be useful in the further characterization ofEselectin ligands and the obtained results encourage further studies on the consequences of the FUT7-G329A mutation in vivo.
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| 15. |
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| 16. |
- Bengtson, Per, et al.
(författare)
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Evidence of a strong coupling between root exudation, C and N availability, and stimulated SOM decomposition caused by rhizosphere priming effects
- 2012
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Ingår i: Ecology and Evolution. - : Wiley. - 2045-7758. ; 2:8, s. 1843-1852
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Tidskriftsartikel (refereegranskat)abstract
- Increased temperatures and concomitant changes in vegetation patterns are expected to dramatically alter the functioning of northern ecosystems over the next few decades. Predicting the ecosystem response to such a shift in climate and vegetation is complicated by the lack of knowledge about the links between aboveground biota and belowground process rates. Current models suggest that increasing temperatures and rising concentrations of atmospheric CO2 will be partly mitigated by elevated C sequestration in plant biomass and soil. However, empirical evidence does not always support this assumption, as elevated temperature and CO2 concentrations also accelerate the belowground C flux, in many cases extending to increased decomposition of soil organic matter (SOM) and ultimately resulting in decreased soil C stocks. The mechanism behind the increase has remained largely unknown, but it has been suggested that priming might be the causative agent. Here, we provide quantitative evidence of a strong coupling between root exudation, SOM decomposition, and release of plant available N caused by rhizosphere priming effects. As plants tend to increase belowground C allocation with increased temperatures and CO2 concentrations, priming effects need to be considered in our long-term analysis of soil C budgets in a changing environment. The extent of priming seems to be intimately linked to resource availability, as shifts in the stoichiometric nutrient demands of plants and microorganisms will lead to either cooperation (resulting in priming) or competition (no priming will occur). The findings lead us on the way to resolve the varying response of primary production, SOM decomposition, and release of plant available N to elevated temperatures, CO2 concentrations, and N availability.
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| 17. |
- Bengtson, Per, et al.
(författare)
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Identification of a Missense Mutation (G329A; Arg110→ Gln) in the Human FUT7 Gene
- 2001
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Ingår i: Journal of Biological Chemistry. - 0021-9258 .- 1083-351X. ; 276:34, s. 31575-31582
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Tidskriftsartikel (refereegranskat)abstract
- The human FUT7 gene codes for the α1,3-fucosyltransferase VII (Fuc-TVII), which is involved in the biosynthesis of the sialyl Lewis x (SLex) epitope on human leukocytes. The FUT7 gene has so far been considered to be monomorphic. Neutrophils isolated from patients with ulcerative colitis were examined for apparent alterations in protein glycosylation patterns by Western blot analysis using monoclonal antibodies directed against SLex and SLex-related epitopes. One individual showed lower levels of SLex expression and an elevated expression of CD65s compared to controls. The coding regions of the FUT7 gene from this individual were cloned, and a G329A point mutation (Arg110 → Gln) was found in one allele, whereas the other FUT7 allele was wild type. No Fuc-TVII enzyme activity was detected in COS-7 cells transiently transfected with the mutated FUT7 construct. TheFUT7 Arg110 is conserved in all previously cloned vertebrate α1,3-fucosyltransferases. Polymerase chain reaction followed by restriction enzyme cleavage was used to screen 364 unselected Caucasians for the G329A mutation, and a frequency of ≤1% for this mutation was found (3 heterozygotes). Genetic characterization of the family members of one of the additional heterozygotes identified one individual carrying the G329A mutation in both FUT7alleles. Peripheral blood neutrophils of this homozygously mutated individual showed a lowered expression of SLex and an elevated expression of CD65s when analyzed by Western blot and flow cytometry. The homozygous individual was diagnosed with ulcer disease, non-insulin-dependent diabetes, osteoporosis, spondyloarthrosis, and Sjögren's syndrome but had no history of recurrent bacterial infections or leukocytosis.
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| 18. |
- Bengtson, Per, et al.
(författare)
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Links between methanotroph community composition and CH(4) oxidation in a pine forest soil
- 2009
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Ingår i: FEMS Microbiology Ecology. - : Oxford University Press (OUP). - 1574-6941 .- 0168-6496. ; 70:3, s. 356-366
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Tidskriftsartikel (refereegranskat)abstract
- The main gap in our knowledge about what determines the rate of CH(4) oxidation in forest soils is the biology of the microorganisms involved, the identity of which remains unclear. In this study, we used stable-isotope probing (SIP) following (13)CH(4) incorporation into phospholipid fatty acids (PLFAs) and DNA/RNA, and sequencing of methane mono-oxygenase (pmoA) genes, to identify the influence of variation in community composition on CH(4) oxidation rates. The rates of (13)C incorporation into PLFAs differed between horizons, with low (13)C incorporation in the organic soil and relatively high (13)C incorporation into the two mineral horizons. The microbial community composition of the methanotrophs incorporating the (13)C label also differed between horizons, and statistical analyses suggested that the methanotroph community composition was a major cause of variation in CH(4) oxidation rates. Both PLFA and pmoA-based data indicated that CH(4) oxidizers in this soil belong to the uncultivated 'upland soil cluster alpha'. CH(4) oxidation potential exhibited the opposite pattern to (13)C incorporation, suggesting that CH(4) oxidation potential assays may correlate poorly with in situ oxidation rates. The DNA/RNA-SIP assay was not successful, most likely due to insufficient (13)C-incorporation into DNA/RNA. The limitations of the technique are briefly discussed.
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| 19. |
- Bengtson, Per
(författare)
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Microbial mobilization and immobilization of soil nitrogen
- 2004
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Microorganisms in forest ecosystems normally recycle nitrogen (N), such that gaseous losses and leaching are limited. Mobilization of organic N, including microbial N, and immobilization of inorganic N, especially NH4+, are the quantitatively most important N transformation processes. Various factors influence their rates, e.g. the amount of carbon and nitrogen, temperature, moisture, and the microbial biomass and activity. The factors are adressed in the thesis with the ambition to suggest mechanistic explanations for their influence on nitrogen mobilization and immobilization rates. The mineralization and immobilization rates are not dependent on the concentration of carbon or nitrogen per se, but rather on the microbial biomass and its activity. This may invalidate the use of first order kinetics to describe mobilization and immobilization rates. Earlier claims that mineralization and immobilization rates are dependent on the concentration of carbon and nitrogen may have overseen the dependence of the microbial biomass on the soil organic matter content. Moisture, temperature, and the quality of the utilized organic matter appear to determine the activity of the microorganisms. Mobilization of microbially bound N seem to occur mainly as a result of predation and drying-rewetting cycles, since microorganisms have an efficient intracellular recycling of nitrogen, especially at low ammonium concentrations. Thus, mobilization and remineralization of microbial nitrogen by other processes than predation and drying-rewetting cycles is likely to occur only when conditions promote high growth rates, i.e. when microorganisms are not substrate limited and temperature and moisture conditions are favourable. The main factors determining microbial mobilization and immobilization of soil N are therefore the size of the microbial biomass, its activity, and the quality of the growth substrate. Those three factors in turn seem to be dependent on soil SOM content, predation, drying-rewetting cycles, temperature, and soil water content.
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| 20. |
- Bengtson, Per, et al.
(författare)
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Polymorphonuclear Leukocytes from Individuals Carrying the G329A Mutation in the α1,3-Fucosyltransferase VII Gene (FUT7) Roll on E- and P-Selectins
- 2002
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Ingår i: Journal of Immunology. - 0022-1767 .- 1550-6606. ; 169:7, s. 3940-3946
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Tidskriftsartikel (refereegranskat)abstract
- We recently identified several individuals carrying a missense mutation (G329A; Arg110-Gln) in the FUT7 gene encoding fucosyltransferase VII. This enzyme is involved in the biosynthesis of the sialyl Lewis x (Lex) epitope on human leukocytes, which has been identified as an important component of leukocyte ligands for E- and P-selectin. No enzyme activity was measurable in expression studies in COS-7 cells using the mutated FUT7 construct. One of the identified individuals carried this mutation homozygously. Flow cytometry analysis of polymorphonuclear leukocytes (PMN) from this individual showed a nearly complete absence of staining with mAbs directed against sialyl Lex and a diminished staining with an E-selectin IgG chimera. However, staining with P-selectin IgG chimera and Abs directed against P-selectin glycoprotein ligand-1 was not affected by the mutation. PMN from the homozygously mutated individual was further analyzed in an in vitro flow chamber assay. The number of rolling PMN and the rolling velocities on both E- and P-selectin were in the range of PMN from nonmutated individuals. FUT4 and FUT7 mRNA was quantified in PMN isolated from individuals carrying the FUT7 mutation. It was found that PMN from both FUT7 homozygously and heterozygously mutated individuals exhibited an elevated expression of FUT4 mRNA compared with PMN from FUT7 nonmutated individuals. The elevated expression of fucosyltransferase IV was reflected as an increased expression of the Lex and CD65s Ags on PMN from these individuals. The significance of the mutation was supported by transfection of BJAB cells.
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| 21. |
- Bengtson, Per, et al.
(författare)
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Possible role of reactive chlorine in microbial antagonism and organic matter chlorination in terrestrial environments
- 2009
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Ingår i: Environmental Microbiology. - : Wiley. - 1462-2912 .- 1462-2920. ; 11:6, s. 1330-1339
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Forskningsöversikt (refereegranskat)abstract
- Several studies have demonstrated that extensive formation of organically bound chlorine occurs both in soil and in decaying plant material. Previous studies suggest that enzymatic formation of reactive chlorine outside cells is a major source. However, the ecological role of microbial-induced extracellular chlorination processes remains unclear. In the present paper, we assess whether or not the literature supports the hypothesis that extracellular chlorination is involved in direct antagonism against competitors for the same resources. Our review shows that it is by no means rare that biotic processes create conditions that render biocidal concentrations of reactive chlorine compounds, which suggest that extracellular production of reactive chlorine may have an important role in antagonistic microbial interactions. To test the validity, we searched the UniprotPK database for microorganisms that are known to produce haloperoxidases. It appeared that many of the identified haloperoxidases from terrestrial environments are originating from organisms that are associated with living plants or decomposing plant material. The results of the in silico screening were supported by various field and laboratory studies on natural chlorination. Hence, the ability to produce reactive chlorine seems to be especially common in environments that are known for antibiotic-mediated competition for resources (interference competition). Yet, the ability to produce haloperoxidases is also recorded, for example, for plant endosymbionts and parasites, and there is little or no empirical evidence that suggests that these organisms are antagonistic.
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| 22. |
- Bengtson, Per, et al.
(författare)
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Possible roles of reactive chlorine II: assessing biotic chlorination as a way for organisms to handle oxygen stress
- 2013
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Ingår i: Environmental Microbiology. - : Wiley-Blackwell. - 1462-2912 .- 1462-2920. ; 15:4, s. 991-1000
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Forskningsöversikt (refereegranskat)abstract
- Natural formation of organically bound chlorine is extensive in many environments. The enzymes associated with the formation of chlorinated organic matter are produced by a large variety of organisms. Little is known about the ecological role of the process, the key question being: why do microorganisms promote chlorination of organic matter? In a recent paper we discuss whether organic matter chlorination may be a result of antagonistic interactions among microorganisms. In the present paper we evaluate whether extracellular microbial formation of reactive chlorine may be used as a defence against oxygen stress, and we discuss whether this process is likely to contribute to the formation of chlorinated organic matter. Our analysis suggests that periodic exposure to elevated concentrations of reactive oxygen species is a common denominator among the multitude of organisms that are able to enzymatically catalyse formation of reactive chlorine. There is also some evidence suggesting that the production of such enzymes in algae and bacteria is induced by oxygen stress. The relative contribution from this process to the extensive formation of chlorinated organic matter in natural environments remains to be empirically assessed.
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| 23. |
- Bengtson, Per, et al.
(författare)
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Rapid turnover of DOC in temperate forests accounts for increased CO2 production at elevated temperatures
- 2007
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Ingår i: Ecology Letters. - : Wiley. - 1461-023X .- 1461-0248. ; 10:9, s. 783-790
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- The evidence for the contribution of soil warming to changes in atmospheric CO2 concentrations and carbon stocks of temperate forest ecosystems is equivocal. Here, we use data from a beech/oak forest on concentrations and stable isotope ratios of dissolved organic carbon (DOC), phosphate buffer-extractable organic carbon, soil organic carbon (SOC), respiration and microbial gross assimilation of N to show that respired soil carbon originated from DOC. However, the respiration was not dependent on the DOC concentration but exceeded the daily DOC pool three to four times, suggesting that DOC was turned over several times per day. A mass flow model helped to calculate that a maximum of 40% of the daily DOC production was derived from SOC and to demonstrate that degradation of SOC is limiting respiration of DOC. The carbon flow model on SOC, DOC, microbial C mobilization/immobilization and respiration is linked by temperature-dependent microbial and enzyme activity to global warming effects Of CO2 emitted to the atmosphere.
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| 24. |
- Bengtson, Per, et al.
(författare)
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Relieving substrate limitation-soil moisture and temperature determine gross N transformation rates
- 2005
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Ingår i: Oikos. - : Wiley. - 1600-0706 .- 0030-1299. ; 111:1, s. 81-90
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Tidskriftsartikel (refereegranskat)abstract
- A field experiment was designed with the objective to reveal the interactions between soil moisture, temperature, total, dissolved, and phosphate buffer extractable C and N, and microbial activity in the control of in situ gross N mineralization and immobilization rates in a deciduous forest. We had three alternative hypotheses to explain variations of the gross N transformations: 1) microorganisms are C limited, 2) microorganisms are N limited, or 3) neither C nor N limit the microorganisms but moisture and temperature conditions. Each hypothesis had specific criteria to be fulfilled for its acceptance. The results demonstrated that gross N transformation rates were more dependent on and variable with soil moisture and temperature than the size of the different C and N pools. The immobilization of N was dependent on the gross mineralization rate, suggesting that the production of enzymes for mineralization of organic N and the immobilization of N from the surrounding soil is disconfirmed when the intracellular N content of the microorganisms is sufficiently high. If the microorganisms are starved for N, enzyme systems involved in both the assimilation and mineralization of N are activated. The mean in situ gross N mineralization rate was two orders of magnitude higher than the natural N deposition in the area and the N addition in the NITREX experiments, meaning that a reduction in the gross N mineralization rate of about 1% would be enough to compensate for the addition of inorganic N. This decrease would hardly be detectable given the great spatial and temporal variability of N transformation rates.
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| 25. |
- Bengtson, Per, et al.
(författare)
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Serum transferrin carrying the xeno-tetrasaccharide NeuAc-Gal-GlcNAc2 is a biomarker of ALG1-CDG.
- 2016
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Ingår i: Journal of Inherited Metabolic Disease. - : Wiley. - 0141-8955 .- 1573-2665. ; 39:1, s. 107-114
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Tidskriftsartikel (refereegranskat)abstract
- ALG1-CDG (formerly CDG-Ik) is a subtype of congenital disorders of glycosylation (CDG) where the genetic defect disrupts the synthesis of the lipid-linked oligosaccharide precursor required for N-glycosylation. The initial step in the investigation for these disorders involves the demonstration of hypoglycosylated serum transferrin (TF). There are no specific biomarkers of this CDG subtype known to date. An LC/MS approach was used to analyze sera from patients with ALG1-CDG, PMM2-CDG, suspected CDG, and individuals with alcohol abuse. We show mass spectrometric data combined with data from enzymatic digestions that suggest the presence of a tetrasaccharide consisting of two N-acetylglucosamines, one galactose, and one sialic acid, appearing on serum TF, is a biomarker of this particular CDG subtype. This is the first time analysis of serum TF can suggest a specific CDG type I subtype and we suggest this tetrasaccharide be used in the clinic to guide the ALG1-CDG diagnostic process.
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| 26. |
- Bengtson, Per, et al.
(författare)
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Spatial distributions of plants and gross N transformation rates in a forest soil
- 2006
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Ingår i: Journal of Ecology. - : Wiley. - 1365-2745 .- 0022-0477. ; 94:4, s. 754-764
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- 1 This work demonstrates that spatial distribution of understorey vegetation and gross N transformation rates in a mixed beach-oak forest is closely correlated within a distance of a few metres. The findings imply that plant diversity and productivity have a major influence on gross rates of N transformation and vice versa. 2 A geostatistical analysis was used to evaluate the spatial relationships between abundance and species composition of the understorey vegetation and in situ gross N mineralization, NH4+ immobolization and nitrification rates. 3 The gross N transformation rates and the plants spatial variation were correlated within the forest, but plant distribution was more dependent on the fraction of mineralized N that was nitrified than on individual N transformation rates. 4 The total cover of the understorey vegetation varied more in space than the species composition, and was higher in areas with high N transformation rates. 5 Plant species benefiting from high net nitrification rates were more common in areas with a low activity of mineralizing and nitrifying microorganisms, possibly because the net and gross rates were independent of each other. In fact, those species occurred most often in areas in which a large fraction of mineralized N was nitrified. 6 Beech and oak trees also had an effect on the spatial variation of the understorey vegetation. Beech trees provided conditions more suitable for plants benefiting from NO3-, whereas the vascular plant cover was greater under oak trees, probably in response to a higher light interception than under beech trees. 7 Oak generally had a positive impact on gross N transformation rates compared with beech, perhaps reflecting differences in litter quality and climate caused by the two species. 8 The influence of trees alone could not explain the full magnitude of the variation of N transformation rates or the presence of overlapping areas with high mineralization and immobilization rates. These were probably caused by other factors, such as soil moisture content. 9 This work sheds new light on the small-scale spatial links between above-ground plant diversity and abundance, and below-ground microbial N transformations.
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| 27. |
- Bengtsson, Göran, et al.
(författare)
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Gross nitrogen mineralization-, immobilization-, and nitrification rates as a function of soil C/N ratio and microbial activity
- 2003
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Ingår i: Soil Biology & Biochemistry. - 0038-0717. ; 35:1, s. 143-154
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Tidskriftsartikel (refereegranskat)abstract
- A laboratory experiment was designed to challenge the idea that the ON ratio of forest soils may control gross N immobilization, mineralization, and nitrification rates. Soils were collected from three deciduous forests sites varying in C/N ratio between 15 and 27. They were air-dried and rewetted to induce a burst of microbial activity. The N transformation rates were calculated from an isotope dilution and enrichment procedure, in which (NH4Cl)-N-15 or (NaNO3)-N-15 was repeatedly added to the soils during 7 days of incubation. The experiments suggested that differences in gross nitrogen immobilization and mineralization rates between the soils were more related to the respiration rate and ATP content than to the C/N ratio. Peaks of respiration and ATP content were followed by high rates of mineralization and immobilization, with 1-2 days of delay. The gross immobilization of NH4+ was dependent on the gross mineralization and one to two orders of magnitude larger than the gross NO3- immobilization. The gross nitrification rates were negatively related to the ATP content and the C/N ratio and greatly exceeding the net nitrification rates. Taken together, the observations suggest that leaching of nitrate from forest soils may be largely dependent on the density and activity of the microbial community.
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| 28. |
- Berg, Tove, et al.
(författare)
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Naturvägledning i Sverige 2022 - nuläge och framtidsperspektiv
- 2022
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Rapport (populärvet., debatt m.m.)abstract
- I den här rapporten presenteras en nulägesbeskrivning av naturvägledning i Sverige samt utmaningar och möjligheter när vi blickar framåt. Rapportens första del fokuserar på naturvägledning hos kommuner och länsstyrelser och hur naturvägledning kommer in i deras arbete idag. Granskningarna tar sin grund i Naturvårdsverkets enkäter om kommuners och länsstyrelsers arbete för att nå friluftsmålen, åren 2019–2022. Genom en tematisk analys söker vi efter trender i deras strategier, metoder och motiv till naturvägledning. Denna nulägesbeskrivning behandlar alltså naturvägledning som sker genom kommuner och länsstyrelser och omfattar inte naturvägledning som andra aktörer utövar och organiserar. Den andra delen av rapporten består av en framtidsspaning om naturvägledning i Sverige. Den tar sin grund i en enkätundersökning som gick ut till SLU Centrum för naturväglednings (CNV:s) sändlista i juni 2022. I sändlistan ingår inte bara naturvägledare inom kommun och länsstyrelse, utan även personer som jobbar med naturvägledning på andra ställen, till exempel inom ideella organisationer, företag, myndigheter och besökscenter. Enkäten besvarades av 155 personer och syftade till att ta del av naturvägledares egna tankar om vilka trender och aktörer som kan påverka naturvägledning framöver, var naturvägledning behövs, och hur naturvägledning kan stärkas. Rapporten pekar på ett antal centrala slutsatser. I nulägesbeskrivningen framkommer ett stort fokus på naturvägledningens roll för att främja hållbara naturbesök, i en situation där ett högt besökstryck på många platser inneburit ökat slitage. Kopplingen mellan hälsa och naturvistelse tar också en central plats och återkommer som ett motiv för naturvägledning idag, särskilt i länsstyrelsernas arbete. I kommunernas arbete finns en växande trend kring kulturupplevelser i naturen, vilket öppnar för nya sätt att vistas i natur- och kulturmiljöer. Det kan eventuellt även locka nya grupper som inte är lika vana att ta sig ut i naturen. För både kommuner och länsstyrelser finns också en tendens att naturvägledning ökat något under de fyra år som nulägesbeskrivningen omfattar. I framtidsspaningen ger enkäten resultaten att (1) en svagare relation till naturen, samt (2) klimat- och naturkrisen betraktas som de viktigaste omvärldstrenderna som påverkar naturvägledningens framtid. Enkäten visar också att de som svarat tycker att naturvägledning behöver stärkas i skolan, i tätorter samt i vården. Men också på att det finns ett behov av att försöka nå de ”inte redan frälsta”, genom att nå ut med naturvägledning till en bredare skara. En större distans till naturen, både mentalt och fysiskt, samt en minskande kunskap om allemansrätten betraktas som både risker och motiv för naturvägledning i framtiden. Till sist lyfts ett växande intresse för utomhusvistelse och friluftsliv som en trend där naturvägledning kan och bör spela en viktig roll. Naturvägledning är en del av friluftspolitiken men också ett område i sin egen rätt. Det inbegriper en central folkbildningsidé som motiverar naturvägledare liksom många aktörer i friluftslivet. För att naturvägledning ska nå sin fulla potential – både inom friluftsarbetet och generellt för att stärka relationen till och stöd för vård av natur- och kulturmiljöer – behöver området stärkas och utvecklas både i arbetet med framtidens friluftsliv och naturvård. Naturvägledning har potential att vara en viktig del i arbetet med de friluftspolitiska målen, men också för att genomföra de nationella och internationella miljö- och hållbarhetsmålen. Naturvägledning kan bidra till en djupare kunskap och starkare känsla för natur och människan som del av naturen och till engagemang för naturvård. Sammantaget ger denna rapport en tydlig bild av naturvägledningens betydelse i Sverige och att den behöver stöttas och vidareutvecklas i samarbete mellan många aktörer i samhället. Med fokus på upptäckarglädje och inspiration kan naturvägledning bidra till att skapa delaktighet, engagemang och omsorg för vår gemensamma livsmiljö och alla som lever här.
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| 29. |
- Berggren, Martin, et al.
(författare)
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Terrestrial support of zooplankton biomass in northern rivers (invited)
- 2018
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- The contribution of terrestrially-derived carbon to micro-crustacean zooplankton biomass (i.e. allochthony) has been previously studied in lakes and reservoirs, but little is known about allochthony in rivers. We hypothesized that restricted selective grazing in turbulent environments such as rivers would decouple zooplankton from specific microbial and algal food resources, such that their allochthony would mirror the allochthonous contribution to the bulk particle pool. Allochthony was analyzed in 13 widely distributed Swedish rivers, using a dual-isotope mixing model. Zooplankton biomasses were generally low, and allochthony in different micro-crustacean groups (Cladocera, Cyclopoida, Calanoida) varied from 2% to 77%. As predicted, there were no correlations between allochthony and variables such as Chlorophyll-a or bacterial production. Instead, allochthony was similar to the terrestrial contribution in the particulate organic matter, with relationships close to 1:1. The total zooplankton community allochthony was strongly related to the ecosystem metabolic balance between production and respiration, which in turn was dependent upon the ratio between total autochthonous organic carbon concentrations and water color. Our study suggests that micro-crustacean allochthony is regulated differently in rivers compared to in lacustrine systems.
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| 30. |
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| 31. |
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| 32. |
- Campbell, Jocelyn, et al.
(författare)
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Does exogenous carbon extend the realized niche of canopy lichens? Evidence from sub-boreal forests in British Columbia
- 2013
-
Ingår i: Ecology. - : Wiley. - 0012-9658. ; 94:5, s. 1186-1195
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Tidskriftsartikel (refereegranskat)abstract
- Foliose lichens with cyanobacterial bionts (bipartite and tripartite) form a distinct assemblage of epiphytes strongly associated with humid microclimatic conditions in inland British Columbia. Previous research showed that these cyano- and cephalolichen communities are disproportionately abundant and species-rich on conifer saplings beneath Populus compared to beneath other tree species. More revealing, lichens with cyanobacterial bionts were observed beneath Populus even in stands that did not otherwise support them. We experimentally test the hypothesis that this association is due to the interception of glucose-rich nectar that is exuded from Populus extra-floral nectaries (EFN). Using CO2 flux measurements and phospholipid fatty acid (PLFA) analysis with experimental applications of C-13(6)-labeled glucose, we demonstrate that cyano-and cephalolichens have a strong respiratory response to glucose. Lichens treated with glucose had lower net photosynthesis and higher establishment rates than control thalli. Furthermore, lichens with cyanobacterial bionts rapidly incorporate exogenous C-13 into lichen fatty acid tissues. A large proportion of the C-13 taken up by the lichens was incorporated into fungal biomarkers, suggesting that the mycobiont absorbed and assimilated the majority of applied C-13(6) glucose. Our observations suggest that both cyanolichens and cephalolichens may utilize an exogenous source of glucose, made available by poplar EFNs. The exogenous C may enable these lichens to become established by providing a source of C for fungal respiration despite drought-induced inactivity of the cyanobacterial partner. As such, the mycobiont may adopt an alternative nutritional strategy, using available exogenous carbon to extend its realized niche.
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| 33. |
- Carlsson, Michael, et al.
(författare)
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Galectin-3 guides intracellular trafficking of some human serotransferrin glycoforms
- 2013
-
Ingår i: Journal of Biological Chemistry. - 1083-351X. ; 288:39, s. 28398-28408
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Tidskriftsartikel (refereegranskat)abstract
- Transferrin internalization via clathrin-mediated endocytosis and subsequent recycling after iron delivery has been extensively studied. Here we demonstrate a previously unrecognized parameter regulating this recycling -the binding of galectin-3 to particular glycoforms of transferrin. Two fractions of transferrin, separated by affinity chromatography based on their binding or not to galectin-3, are targeted to kinetically different endocytic pathways in HFL-1 cells expressing galectin-3 but not in SKBR3 cells lacking galectin-3; the SKBR3 cells, however can acquire the ability to target these transferrin glycoforms differently after preloading with exogenously added galectin-3. In all, this study provides the first evidence of a functional role for transferrin glycans, in intracellular trafficking after uptake. Moreover, the galectin-3 bound glycoform increased in cancer, suggesting a pathophysiological regulation. These are novel aspects of transferrin cell biology, which has previously considered only degree of iron loading, but not other forms of heterogeneity.
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| 34. |
- Churchland, Carolyn, et al.
(författare)
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Dispersed Variable-Retention Harvesting Mitigates N Losses on Harvested Sites in Conjunction With Changes in Soil Microbial Community Structure
- 2021
-
Ingår i: Frontiers in Forests and Global Change. - : Frontiers Media SA. - 2624-893X. ; 3
-
Tidskriftsartikel (refereegranskat)abstract
- As an alternative to clear-cutting, variable-retention harvesting is now standard forest management practice on the coast of British Columbia and in temperate forests globally, due to the benefits associated with maintaining mature forest species and forest structural diversity. Although there is some evidence that variable-retention harvesting, particularly single-tree (dispersed) retention will mitigate the impacts of clear-cutting on soil microbial communities and nutrient cycling, findings have been inconsistent. We examined microbial community structure (phospholipid-fatty acid), and nutrient availability (PRSTM probes) in a large (aggregated) retention patch and over three harvesting treatments: dispersed retention, clear-cut and clear-cut edge 2 years after harvest. Unlike previous studies, we did not observe elevated nitrate in the harvested areas, instead ammonium was elevated. Availability of N and other nutrients were surprisingly similar between the dispersed-retention treatment and the retention patch. The microbial community, however, was different in the clear-cut and dispersed-retention treatments, mostly due to significantly lower abundance of fungi combined with an increase in bacteria, specifically Gram-negative bacteria. This was accompanied by lower δ13CPDB value of the Gram-negative PLFA's in these treatments, suggesting the decline in mycorrhizal fungal abundance may have allowed the dominant Gram-negative bacteria to access more of the recently photosynthesized C. This shift in the microbial community composition in the dispersed-retention treatment did not appear to have a major impact on microbial functioning and nutrient availability, indicating that this harvesting practice is more effective at maintaining generic microbial functions/processes. However, as Mn levels were twice as high in the retention patch compared to the harvested treatments, indicating the other “narrow” processes (i.e., those performed by a small number of specialized microorganisms), such as lignin degradation, catalyzed by Mn peroxidase, which concomitantly removes Mn from solution, may be more sensitive to harvesting regimes. The effect of harvesting on such narrow nutrient cycling processes requires further investigation.
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| 35. |
- Churchland, Carolyn, et al.
(författare)
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Spatial variability of soil fungal and bacterial abundance: Consequences for carbon turnover along a transition from a forested to clear-cut site
- 2013
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Ingår i: Soil Biology & Biochemistry. - : Elsevier BV. - 0038-0717. ; 63, s. 5-13
-
Tidskriftsartikel (refereegranskat)abstract
- Predicted alterations in belowground plant-allocated C as a result of environmental change may cause compositional shifts in soil microbial communities, and it has been hypothesized that such alterations will influence C mitigation in forest ecosystems. In order to investigate to what degree living trees influence the abundance and activity of mycorrhizal fungi, saprotrophic fungi, and bacteria we used a geostatistical approach to examine natural abundance stable-isotope-ratios of soil microbial PLFAs, respired CO2, and different soil organic C pools in a 100 point grid extending from an area of retention trees into a clear-cut area. Labile C from trees was the major source of C for the fungal communities and influenced the composition of the microbial community and soil respiration rates up to ten meters into the clear-cut. When the input of labile plant C decreased, it appeared that microorganisms became increasingly dependent on recycled C released during microbial turnover, resulting in a decrease in soil respiration. Our findings demonstrate that plants not only influence the structure and function of soil microbial communities but also act as important regulators of belowground C flux, soil C sequestration and, ultimately, soil C stocks. (c) 2013 Elsevier Ltd. All rights reserved.
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| 36. |
- Drevenhorn, Eva, 1954, et al.
(författare)
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Assessment of hypertensive patients' self-care agency after counseling training of nurses
- 2015
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Ingår i: Journal of the American Association of Nurse Practitioners. - : Ovid Technologies (Wolters Kluwer Health). - 2327-6886 .- 2327-6924. ; 27:11, s. 624-630
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Tidskriftsartikel (refereegranskat)abstract
- PurposeThe aim of the study was to assess hypertensive patients' self-care agency and any correlation with the patient's lifestyle changes and the nurse's degree of patient centeredness after counseling training. Data sourcesNurses in the intervention group (IG; n = 19) working at nurse-led clinics at health centers were trained in patient centeredness (motivational interviewing) and the stages of change model and included 137 patients. Nurses in the control group (CG; n = 14) included 51 patients. The Exercise of Self-Care Agency (ESCA) instrument was used. There was a significant difference from baseline to the 2-year follow-up in the ESCA score (IG, p = .0001). An increase in ESCA score was correlated with an increased level of physical activity after 2 years (IG, p = .0001; CG, p = .040). ConclusionsThe counseling training gave an increase in the patients' self-care agency scores, which was significantly correlated with increased physical activity. Implications for practiceIn clinical practice it is important for nurses to be patient centered in their counseling to affect patients' self-care agency in a positive direction.
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| 37. |
- Drevenhorn, Eva, et al.
(författare)
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Consultation training of nurses for cardiovascular prevention - A randomized study of 2 years duration
- 2012
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Ingår i: Blood Pressure. - : Informa Healthcare. - 0803-7051 .- 1651-1999. ; 21:5, s. 293-299
-
Tidskriftsartikel (refereegranskat)abstract
- The aim of this study was to increase patients adherence to the treatment of hypertension through the consultation training of nurses. Thirty-three nurses were included in the study. In the intervention group (IG), 19 nurses took part in a 3-day residential training course on the Stages of Change model, Motivational Interviewing and guidelines for cardiovascular prevention, and recruited 153 patients. Sixteen nurses in the control group (CG) recruited 59 patients. A decrease in systolic and diastolic blood pressure and total cholesterol was noticed in both groups over the 2 years. Heart rate (p = 0.027), body mass index (p = 0.019), weight (p = 0.0001), waist (p = 0.041), low-density lipoprotein-cholesterol (p = 0.0001), the waist-hip ratio (p = 0.024), and perceived stress (p = 0.001) decreased to any great extent only in the IG. After 2 years, 52.6% of the patients in the IG (p = 0.13) reached the target of andlt;= 140/90 mmHg in blood pressure compared with 39.2% in the CG. For self-reported physical activity, there was a significant (p = 0.021) difference between the groups. The beneficial effects of the consultation training on patients weight parameters, physical activity, perceived stress and the proportion of patients who achieved blood pressure control emphasize consultation training and the use of behavioural models in motivating patients to adhere to treatment.
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| 38. |
- Drevenhorn, Eva, et al.
(författare)
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Effects on hypertensive patients' satisfaction with information about their medication after nurses' consultation training
- 2014
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Ingår i: Pragmatic and Observational Research. - : Dove Press. - 1179-7266. ; 5, s. 35-41
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Tidskriftsartikel (refereegranskat)abstract
- Background: There is a well-known problem in hypertension care with patients' adherence to treatment. Patients who score high in answering the instrument Satisfaction with Information about Medicine Scale are reported to have greater adherence to their medication.Aim: To explore how hypertensive patients' satisfaction with information about their medicines was affected by nurses' education in Motivational Interviewing.Material and methods: The Stages of Change model and Motivational Interviewing was the theoretical base for consultation training for nurses. Nineteen nurses attended 3 days of video-recorded consultation training with simulated patients. They were updated in hypertensive medication and were trained in motivating patients to improve their self-management as well as adherence to lifestyle changes and medication. The satisfaction with information instrument identifies patients' satisfaction with information about the action and usage of medication as well as potential problems with it. The instrument was used to assess how well the needs of individual patients for medicine information were met at baseline and 2 years after the training. The 19 trained nurses in the intervention group worked with 137 patients, and a control group of 16 nurses, who gave normal care, worked with 51 patients.Results: There was a difference between the intervention and control group in total score (P=0.028) 2 years after the intervention. Patients in the intervention group perceived higher satisfaction with the action and usage of their medication (P=0.001) and a lower degree of potential problems with their medication (P=0.001). Patients in the control group also perceived a lower degree of potential problems with their medication (P=0.028).Conclusion: We suggest that consultation training for nurses with the aim of motivating patients to be more self-directed in their self-care improves satisfaction with information about medication.
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| 39. |
- Ehtesham, Emad, et al.
(författare)
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Decoupling of soil carbon and nitrogen turnover partly explains increased net ecosystem production in response to nitrogen fertilization
- 2017
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Ingår i: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322. ; 7
-
Tidskriftsartikel (refereegranskat)abstract
- During the last decade there has been an ongoing controversy regarding the extent to which nitrogen fertilization can increase carbon sequestration and net ecosystem production in forest ecosystems. The debate is complicated by the fact that increased nitrogen availability caused by nitrogen deposition has coincided with increasing atmospheric carbon dioxide concentrations. The latter could further stimulate primary production but also result in increased allocation of carbon to root exudates, which could potentially 'prime' the decomposition of soil organic matter. Here we show that increased input of labile carbon to forest soil caused a decoupling of soil carbon and nitrogen cycling, which was manifested as a reduction in respiration of soil organic matter that coincided with a substantial increase in gross nitrogen mineralization. An estimate of the magnitude of the effect demonstrates that the decoupling could potentially result in an increase in net ecosystem production by up to 51 kg C ha-1 day-1 in nitrogen fertilized stands during peak summer. Even if the effect is several times lower on an annual basis, the results still suggest that nitrogen fertilization can have a much stronger influence on net ecosystem production than can be expected from a direct stimulation of primary production alone.
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| 40. |
- Erinle, Kehinde O., et al.
(författare)
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Rewetting Intensity Influences Soil Respiration and Nitrogen Availability
- 2021
-
Ingår i: Journal of Soil Science and Plant Nutrition. - : Springer Science and Business Media LLC. - 0718-9508 .- 0718-9516. ; 21:3, s. 2137-2144
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Tidskriftsartikel (refereegranskat)abstract
- It is not clear how different rewetting intensities (rapid, slow or partial rewetting) influence soil respiration and nitrogen (N) availability. Moist soil left unamended or amended with low C/N faba bean residue and incubated for 21 days was dried to <5% WHC within 3 days. After 14 days of incubation, dry soils were rewetted to 50% water holding capacity (WHC), once within few seconds (rapid), by two applications at 25% WHC each, with 6-h interval between rewetting events (slow), or single application at 25% WHC (partial). The soils were further incubated for another 14 days. One day after rewetting in unamended and amended soils, respiration rate followed the order slow > rapid > partial rewetting. From day 4 onwards, moisture treatments differed little in respiration rate. In unamended soils, the rewetting intensity had little effect on available N. But 1 day after rewetting, MBN was lowest in CM, and twofold, fourfold and tenfold higher with rapid, slow and partial rewetting, respectively. In amended soils 1 day after rewetting, available N was about twofold higher in CM and with rapid than slow and partial rewetting, while MBN was about twofold higher with CM and rapid rewetting than slow and partial rewetting. Treatments differed little in available N and MBN 7 and 14 days after rewetting. Slow rewetting induced greater soil respiration and microbial N uptake than rapid rewetting. But effects were short-lived.
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| 41. |
- Glimelius, Bengt, et al.
(författare)
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Persistent prevention of oxaliplatin-induced peripheral neuropathy using calmangafodipir (PledOx®) : a placebo-controlled randomised phase II study (PLIANT)
- 2018
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Ingår i: Acta Oncologica. - 0284-186X .- 1651-226X. ; 57:3, s. 393-402
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Tidskriftsartikel (refereegranskat)abstract
- Purpose: Oxaliplatin causes disabling acute and chronic peripheral neuropathy. We explored the preventive effects of calmangafodipir, mimicking the mitochondrial enzyme manganese superoxide dismutase, thereby protecting cells from oxidative stress, in a placebo-controlled, double-blinded randomised phase II study (ClinicalTrials.gov.NCT01619423) in patients with metastatic colorectal cancer (mCRC).Patient and methods: mCRC patients treated with modified FOLFOX-6 (folinic acid 200 mg/m2, 5-fluorouracil bolus 400 mg/m2, oxaliplatin 85 mg/m2 and 5-fluorouracil 2400 mg/m2 continuous infusion for 46 h) every fortnight for 8 cycles in first or second line were eligible. Calmangafodipir was given in a phase I dose-finding and in a phase II placebo-controlled study, as a 5-min infusion 10 min prior to oxaliplatin. Neurotoxicity was evaluated by the physician using the Oxaliplatin Sanofi Specific Scale and by the patient using the cold allodynia test and the Leonard scale.Results: Eleven patients were included in phase I without any detectable toxicity to calmangafodipir. In the phase II study, 173 patients were randomised to placebo (n = 60), calmangafodipir 2 µmol/kg (n = 57) and calmangafodipir 5 µmol/kg (n = 45, initially 10 µmol/kg, n = 11). Calmangafodipir-treated patients (all three doses pooled) had less physician graded neurotoxicity (odds ratio (90% confidence interval one-sided upper level) 0.62(1.15), p = .16), significantly less problems with cold allodynia (mean 1.6 versus 2.3, p < .05) and significantly fewer sensory symptoms in the Leonard scale (cycle 1–8 mean 1.9 versus 3.0, p < .05 and during follow-up after 3 and 6 months, mean 3.5 versus 7.3, p < .01). Response rate, progression-free and overall survival did not differ among groups.Conclusions: Calmangafodipir at a dose of 5 µmol/kg appears to prevent the development of oxaliplatin-induced acute and delayed CIPN without apparent influence on tumour outcomes.
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| 42. |
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| 43. |
- Gåfvels, Mats, et al.
(författare)
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A fast semi-quantitative LC-MS method for measurement of intact apolipoprotein A-I reveals novel proteoforms in serum.
- 2015
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Ingår i: Clinica Chimica Acta. - : Elsevier BV. - 0009-8981. ; 442:Jan 17, s. 87-95
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Tidskriftsartikel (refereegranskat)abstract
- Surrogate markers for reverse cholesterol transport (RCT) efficiency such as HDL cholesterol and immune methods for apolipoprotein A-I (ApoA-I) may not fully reflect the actual efficiency of the RCT pathway. Several genetic variants and different posttranslational proteoforms of ApoA-I may unevenly affect the functionality of the HDL particle to efflux cholesterol. A method employing top-down immunoaffinity LC-MS of ApoA-I in order to characterize the most prevalent ApoA-I proteoforms in human plasma is described.
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| 44. |
- Hedlund, Maria, et al.
(författare)
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Galectin mediated tethering and arrest of neutrophils under shear flow conditions
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- According to the conventional wisdom leukocyte recruitment to an inflammatory site is initiated by selectin mediated capture and rolling along the activated endothelium. The galectins are members of another family oflectins with affinity for ß-galactosides. Expressed on endothelial cells, galectin-1 and galectin-3 have been proposed to mediate cell-cell interactions during inflammation and tumor cell metastasis, and hence act as an alternative to selectins/integrins under certain circumstances. To begin testing this hypothesis, we examined the interaction of neutrophils -with a galectin-1 or galectin-3 coated surface under shear flow conditions. Both galectins were found to trigger neutrophil arrest in a dose and carbohydrate dependent manner at coating concentrations of ≥ 200 nM, and 1 dynes/cm2 wall shear stress. While, galectin-3 mediated neutrophil arrest was immediate, galectin-1 triggered a brief period of tethering before arrest. Rapidly following arrest neutrophils spread onto the galectin-coated surface. Cell spreading was accompanied by a redistribution of actin filaments, from an initial even staining with FITC-phalloidin to a more peripheral distribution in spread cells. These data suggest that galectin-1 and galectin-3 may act as adhesion molecules capturing and arresting neutrophils at sites knovvn to be less dependent on selectins and ß2integrins. They behave in part like selectins in capturing the neutrophils, but also like the integrins in triggering firm adhesion and cell spreading.
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| 45. |
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| 46. |
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| 47. |
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| 48. |
- Holmstedt, Göran, et al.
(författare)
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Determination of uncertainty of different CFD codes by means of comparison with experimental fire scenarios
- 2009
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Ingår i: Conference Proceedings - Fire and Materials 2009, 11th International Conference and Exhibition.
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Konferensbidrag (refereegranskat)abstract
- This article will summarise the evaluation of four CFD software codes (CFX, FDS4, SMAFS and SOFIE). Evaluation was performed by means of comparing the simulation data with experimental scenarios. The scenarios were chosen to represent scenarios frequently assessed using fire safety design based on performance. The greatest difficulty during validation of CFD-codes is to find well documented relevant experiments. It is true that many large scale experiments including smoke spread have been published but many of them are not described sufficiently and are therefore impossible to use for validation. It is very unusual that data on reproducibility and repeatability is available. After an extensive discussion between the participants in the project five scenarios were chosen. Scenarios 1A (large room with vents), and scenarios 1B1 and 1B2 (corridor with vents) were well documented experiments (repeatability) with ceiling vents and ceiling jets performed earlier at SP in Boras. Scenario 2 is a tunnel fire taken from an experimental study in Boston, US. Scenario 3 is an atrium fire taken from an experimental study in Japan. Lack of well documented fires in retail premises lead us to perform a series of tests in 1/2 scale, 4.1 and 4.2 at SP in Boras. Scenario 5 is an experimental study from Australia including smoke spread from a fire room to an adjacent corridor and a room. The conditions for the simulations included information about the scenarios given above. No information about experimental results was available until the results from the simulations had been sent in to the project manager. The intention was to imitate the working conditions for a consultant as far as possible when using a CFD-simulation to estimate fire safety. In this manner the simulations are dependent on many factors such as the CFD-code used, judgement of input data of the scenarios done by the operator, operator skill etc. The results from the evaluation of the CFD codes showed that the simulation results generally were a good description of the experimental fires studied, but that limitations and specific properties of the different codes, together with the operator factor, can strongly influence the results. The detailed results of all comparisons are given in the final report of the project. It was not possible to include these detailed evaluations in this conference paper but these results are available in the main report as well as in future scientific articles.
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| 49. |
- Holmstedt, Göran, et al.
(författare)
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Validation of CFD codes
- 2008
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Use of CFD (computional fluid dynamics) softwarepackages within fire performance based engineeringand risk assessment is increasing substantially.An important part in the process is thequality assurance. For this reason the SwedishRescue Services Agency (SRV) sponsored aunique research project. Within the project differentcodes for smoke spread and evacuationhave been evaluated. This poster will focus onthe evaluation of four CFD software codes.
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| 50. |
- Karhu, Kristiina, et al.
(författare)
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Microbial carbon use efficiency and priming of soil organic matter mineralization by glucose additions in boreal forest soils with different C:N ratios
- 2022
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Ingår i: Soil Biology and Biochemistry. - : Elsevier BV. - 0038-0717. ; 167
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Tidskriftsartikel (refereegranskat)abstract
- During the last decade it has been increasingly acknowledged that carbon (C) contained in root exudates can accelerate decomposition of soil organic matter (SOM), a phenomenon known as rhizosphere priming effect (RPE). However, the controlling factors and the role of different soil microorganisms in RPE are not yet well understood. There are some indications that the response of the soil microbial decomposers to labile C input in the rhizosphere depends on microbial demand of nutrients for growth and maintenance, especially that of C and nitrogen (N). To test this hypothesis, we assessed SOM decomposition induced by 13C-glucose additions during one week in forest soils with different C:N ratios (11.5–22.2). We estimated SOM respiration, the potential activity (concentration) of a range of extracellular enzymes, and incorporation of 13C and deuterium (D) in microbial phospholipid fatty acids (PLFAs). Glucose additions induced positive priming (a 12–52% increase in SOM respiration) in all soil types, but there was no linear relationship between priming and the soil C:N ratio. Instead, priming of SOM respiration was positively linked to the C:N imbalance, where a higher C:N imbalance implies stronger microbial N limitation. The total oxidative enzyme activity and the ratio between the activities of C and N acquiring enzymes were lower in soil with higher C:N ratios, but these findings could not be quantitatively linked to the observed priming rates. It appears as if glucose addition resulted in priming by stimulating the activity rather than the concentration of oxidative enzymes. Microbial incorporation of D and 13C into in PLFAs demonstrated that glucose additions stimulated both fungal and bacterial growth. The increased growth was mainly supported by glucose assimilation in fungi, while the increase in bacterial growth partly was a result of increased availability of C or N released from SOM. Taken together, the findings suggest that the soil C:N ratio is a poor predictor of priming and that priming is more dependent on the C:N imbalance, which reflects both microbial nutrient demand and nutrient provision.
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