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Shevtsova, Anna
Publications (10 of 14) Show all publications
De Frenne, P., Blondeel, H., Brunet, J., Caron, M. M., Chabrerie, O., Cougnon, M., . . . Verheyen, K. (2018). Atmospheric nitrogen deposition on petals enhances seed quality of the forest herb Anemone nemorosa. Plant Biology, 20(3), 619-626
Open this publication in new window or tab >>Atmospheric nitrogen deposition on petals enhances seed quality of the forest herb Anemone nemorosa
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2018 (English)In: Plant Biology, ISSN 1435-8603, E-ISSN 1438-8677, Vol. 20, no 3, p. 619-626Article in journal (Refereed) Published
Abstract [en]

Elevated atmospheric input of nitrogen (N) is currently affecting plant biodiversity and ecosystem functioning. The growth and survival of numerous plant species is known to respond strongly to N fertilisation. Yet, few studies have assessed the effects of N deposition on seed quality and reproductive performance, which is an important life-history stage of plants. Here we address this knowledge gap by assessing the effects of atmospheric N deposition on seed quality of the ancient forest herb Anemone nemorosa using two complementary approaches. By taking advantage of the wide spatiotemporal variation in N deposition rates in pan-European temperate and boreal forests over 2years, we detected positive effects of N deposition on the N concentration (percentage N per unit seed mass, increased from 2.8% to 4.1%) and N content (total N mass per seed more than doubled) of A.nemorosa seeds. In a complementary experiment, we applied ammonium nitrate to aboveground plant tissues and the soil surface to determine whether dissolved N sources in precipitation could be incorporated into seeds. Although the addition of N to leaves and the soil surface had no effect, a concentrated N solution applied to petals during anthesis resulted in increased seed mass, seed N concentration and N content. Our results demonstrate that N deposition on the petals enhances bioaccumulation of N in the seeds of A.nemorosa. Enhanced atmospheric inputs of N can thus not only affect growth and population dynamics via root or canopy uptake, but can also influence seed quality and reproduction via intake through the inflorescences.

Keywords
Latitudinal gradient, nitrogen deposition, nutrient stoichiometry, seed provisioning, seed quality, xual reproduction, wood anemone
National Category
Botany
Identifiers
urn:nbn:se:umu:diva-147451 (URN)10.1111/plb.12688 (DOI)000430010500025 ()29323793 (PubMedID)
Available from: 2018-06-15 Created: 2018-06-15 Last updated: 2018-06-15Bibliographically approved
Bugaytsova, J. A., Björnham, O., Chernov, Y. A., Gideonsson, P., Henriksson, S., Mendez, M., . . . Boren, T. (2017). Helicobacter pylori Adapts to Chronic Infection and Gastric Disease via pH-Responsive BabA-Mediated Adherence. Cell Host and Microbe, 21(3), 376-389
Open this publication in new window or tab >>Helicobacter pylori Adapts to Chronic Infection and Gastric Disease via pH-Responsive BabA-Mediated Adherence
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2017 (English)In: Cell Host and Microbe, ISSN 1931-3128, E-ISSN 1934-6069, Vol. 21, no 3, p. 376-389Article in journal (Refereed) Published
Abstract [en]

The BabA adhesin mediates high-affinity binding of Helicobacter pylori to the ABO blood group antigen-glycosylated gastric mucosa. Here we show that BabA is acid responsive-binding is reduced at low pH and restored by acid neutralization. Acid responsiveness differs among strains; often correlates with different intragastric regions and evolves during chronic infection and disease progression; and depends on pH sensor sequences in BabA and on pH reversible formation of high-affinity binding BabA multimers. We propose that BabA's extraordinary reversible acid responsiveness enables tight mucosal bacterial adherence while also allowing an effective escape from epithelial cells and mucus that are shed into the acidic bactericidal lumen and that bio-selection and changes in BabA binding properties through mutation and recombination with babA-related genes are selected by differences among individuals and by changes in gastric acidity over time. These processes generate diverse H. pylori subpopulations, in which BabA's adaptive evolution contributes to H. pylori persistence and overt gastric disease.

Place, publisher, year, edition, pages
CELL PRESS, 2017
National Category
Microbiology in the medical area Medical Biotechnology (with a focus on Cell Biology (including Stem Cell Biology), Molecular Biology, Microbiology, Biochemistry or Biopharmacy)
Identifiers
urn:nbn:se:umu:diva-132788 (URN)10.1016/j.chom.2017.02.013 (DOI)000396375600023 ()28279347 (PubMedID)
Available from: 2017-05-11 Created: 2017-05-11 Last updated: 2019-05-24Bibliographically approved
Magalhaes, A., Rossez, Y., Robbe-Masselot, C., Maes, E., Gomes, J., Shevtsova, A., . . . Reis, C. A. (2016). Muc5ac gastric mucin glycosylation is shaped by FUT2 activity and functionally impacts Helicobacter pylori binding. Scientific Reports, 6, Article ID 25575.
Open this publication in new window or tab >>Muc5ac gastric mucin glycosylation is shaped by FUT2 activity and functionally impacts Helicobacter pylori binding
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2016 (English)In: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 6, article id 25575Article in journal (Refereed) Published
Abstract [en]

The gastrointestinal tract is lined by a thick and complex layer of mucus that protects the mucosal epithelium from biochemical and mechanical aggressions. This mucus barrier confers protection against pathogens but also serves as a binding site that supports a sheltered niche of microbial adherence. The carcinogenic bacteria Helicobacter pylori colonize the stomach through binding to host glycans present in the glycocalyx of epithelial cells and extracellular mucus. The secreted MUC5AC mucin is the main component of the gastric mucus layer, and BabA-mediated binding of H. pylori to MUC5AC confers increased risk for overt disease. In this study we unraveled the O-glycosylation profile of Muc5ac from glycoengineered mice models lacking the FUT2 enzyme and therefore mimicking a non-secretor human phenotype. Our results demonstrated that the FUT2 determines the O-glycosylation pattern of Muc5ac, with Fut2 knock-out leading to a marked decrease in alpha 1,2-fucosylated structures and increased expression of the terminal type 1 glycan structure Lewis-a. Importantly, for the first time, we structurally validated the expression of Lewis-a in murine gastric mucosa. Finally, we demonstrated that loss of mucin FUT2-mediated fucosylation impairs gastric mucosal binding of H. pylori BabA adhesin, which is a recognized feature of pathogenicity.

National Category
Microbiology in the medical area Cancer and Oncology
Identifiers
urn:nbn:se:umu:diva-121550 (URN)10.1038/srep25575 (DOI)000375437900001 ()27161092 (PubMedID)
Available from: 2016-07-01 Created: 2016-06-03 Last updated: 2018-06-07Bibliographically approved
Moonens, K., Gideonsson, P., Subedi, S., Bugaytsova, J., Romao, E., Mendez, M., . . . Remaut, H. (2016). Structural Insights into Polymorphic ABO Glycan Binding by Helicobacter pylori. Cell Host and Microbe, 19(1), 55-66
Open this publication in new window or tab >>Structural Insights into Polymorphic ABO Glycan Binding by Helicobacter pylori
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2016 (English)In: Cell Host and Microbe, ISSN 1931-3128, E-ISSN 1934-6069, Vol. 19, no 1, p. 55-66Article in journal (Refereed) Published
Abstract [en]

The Helicobacter pylori adhesin BabA binds mucosal ABO/Le b blood group (bg) carbohydrates. BabA facilitates bacterial attachment to gastric surfaces, increasing strain virulence and forming a recognized risk factor for peptic ulcers and gastric cancer. High sequence variation causes BabA functional diversity, but the underlying structural-molecular determinants are unknown. We generated X-ray structures of representative BabA isoforms that reveal a polymorphic, three-pronged Le(b) binding site. Two diversity loops, DL1 and DL2, provide adaptive control to binding affinity, notably ABO versus O bg preference. H. pylori strains can switch bg preference with single DL1 amino acid substitutions, and can coexpress functionally divergent BabA isoforms. The anchor point for receptor binding is the embrace of an ABO fucose residue by a disulfide-clasped loop, which is inactivated by reduction. Treatment with the redox-active pharmaceutic N-acetylcysteine lowers gastric mucosal neutrophil infiltration in H. pylori-infected Le(b)-expressing mice, providing perspectives on possible H. pylori eradication therapies.

National Category
Cell and Molecular Biology
Identifiers
urn:nbn:se:umu:diva-117839 (URN)10.1016/j.chom.2015.12.004 (DOI)000369839900010 ()26764597 (PubMedID)
Available from: 2016-04-04 Created: 2016-03-04 Last updated: 2018-06-07Bibliographically approved
Lemke, I. H., Kolb, A., Graae, B. J., De Frenne, P., Acharya, K. P., Blandino, C., . . . Diekmann, M. (2015). Patterns of phenotypic trait variation in two temperate forest herbs along a broad climatic gradient. Plant Ecology, 216(11), 1523-1536
Open this publication in new window or tab >>Patterns of phenotypic trait variation in two temperate forest herbs along a broad climatic gradient
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2015 (English)In: Plant Ecology, ISSN 1385-0237, E-ISSN 1573-5052, Vol. 216, no 11, p. 1523-1536Article in journal (Refereed) Published
Abstract [en]

Phenotypic trait variation plays a major role in the response of plants to global environmental change, particularly in species with low migration capabilities and recruitment success. However, little is known about the variation of functional traits within populations and about differences in this variation on larger spatial scales. In a first approach, we therefore related trait expression to climate and local environmental conditions, studying two temperate forest herbs, Milium effusum and Stachys sylvatica, along a similar to 1800-2500 km latitudinal gradient. Within each of 9-10 regions in six European countries, we collected data from six populations of each species and recorded several variables in each region (temperature, precipitation) and population (light availability, soil parameters). For each plant, we measured height, leaf area, specific leaf area, seed mass and the number of seeds and examined environmental effects on within-population trait variation as well as on trait means. Most importantly, trait variation differed both between and within populations. Species, however, differed in their response. Intrapopulation variation in Milium was consistently positively affected by higher mean temperatures and precipitation as well as by more fertile local soil conditions, suggesting that more productive conditions may select for larger phenotypic variation. In Stachys, particularly light availability positively influenced trait variation, whereas local soil conditions had no consistent effects. Generally, our study emphasises that intra-population variation may differ considerably across larger scales-due to phenotypic plasticity and/or underlying genetic diversity-possibly affecting species response to global environmental change.

Keywords
Climate change, Global environmental change, Milium effusum, Phenotypic plasticity, Intraspecific riation, Stachys sylvatica
National Category
Climate Research
Identifiers
urn:nbn:se:umu:diva-113444 (URN)10.1007/s11258-015-0534-0 (DOI)000365170900004 ()
Available from: 2015-12-18 Created: 2015-12-18 Last updated: 2018-06-07Bibliographically approved
Messing, J., Thoele, C., Niehues, M., Shevtsova, A., Glocker, E., Boren, T. & Hensel, A. (2014). Antiadhesive Properties of Abelmoschus esculentus (Okra) Immature Fruit Extract against Helicobacter pylori Adhesion. PLoS ONE, 9(1), e84836
Open this publication in new window or tab >>Antiadhesive Properties of Abelmoschus esculentus (Okra) Immature Fruit Extract against Helicobacter pylori Adhesion
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2014 (English)In: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 9, no 1, p. e84836-Article in journal (Refereed) Published
Abstract [en]

Background: Traditional Asian and African medicine use immature okra fruits (Abelmoschus esculentus) as mucilaginous food to combat gastritis. Its effectiveness is due to polysaccharides that inhibit the adhesion of Helicobacter pylori to stomach tissue. The present study investigates the antiadhesive effect in mechanistic detail. Methodology: A standardized aqueous fresh extract (Okra FE) from immature okra fruits was used for a quantitative in vitro adhesion assay with FITC-labled H. pylori J99, 2 clinical isolates, AGS cells, and fluorescence-activated cell sorting. Bacterial adhesins affected by FE were pinpointed using a dot-blot overlay assay with immobilized Lewis(b), sialyl-Lewis(a), H-1, laminin, and fibronectin. I-125-radiolabeled Okra FE polymer served for binding studies to different H. pylori strains and interaction experiments with BabA and SabA. Iron nanoparticles with different coatings were used to investigate the influence of the charge-dependence of an interaction on the H. pylori surface. Principal findings: Okra FE dose-dependently (0.2 to 2 mg/mL) inhibited H. pylori binding to AGS cells. FE inhibited the adhesive binding of membrane proteins BabA, SabA, and HpA to its specific ligands. Radiolabeled compounds from FE bound non-specifically to different strains of H. pylori, as well as to BabA/SabA deficient mutants, indicating an interaction with a still-unknown membrane structure in the vicinity of the adhesins. The binding depended on the charge of the inhibitors. Okra FE did not lead to subsequent feedback regulation or increased expression of adhesins or virulence factors. Conclusion: Non-specific interactions between high molecular compounds from okra fruits and the H. pylori surface lead to strong antiadhesive effects.

Place, publisher, year, edition, pages
Public Library of Science, 2014
National Category
Medical and Health Sciences
Identifiers
urn:nbn:se:umu:diva-86067 (URN)10.1371/journal.pone.0084836 (DOI)000329866300039 ()
Funder
Swedish Research CouncilSwedish Cancer Society
Available from: 2014-02-17 Created: 2014-02-17 Last updated: 2018-06-08Bibliographically approved
Messing, J., Niehues, M., Shevtsova, A., Boren, T. & Hensel, A. (2014). Antiadhesive Properties of Arabinogalactan Protein from Ribes nigrum Seeds against Bacterial Adhesion of Helicobacter pylori. Molecules, 19(3), 3696-3717
Open this publication in new window or tab >>Antiadhesive Properties of Arabinogalactan Protein from Ribes nigrum Seeds against Bacterial Adhesion of Helicobacter pylori
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2014 (English)In: Molecules, ISSN 1420-3049, E-ISSN 1420-3049, Vol. 19, no 3, p. 3696-3717Article in journal (Refereed) Published
Abstract [en]

Fruit extracts from black currants (Ribes nigrum L.) are traditionally used for treatment of gastritis based on seed polysaccharides that inhibit the adhesion of Helicobacter pylori to stomach cells. For detailed investigations an arabinogalactan protein (F2) was isolated from seeds and characterized concerning molecular weight, carbohydrate, amino acid composition, linkage, configuration and reaction with beta-glucosyl Yariv. Functional testing of F2 was performed by semiquantitative in situ adhesion assay on sections of human gastric mucosa and by quantitative in vitro adhesion assay with FITC-labled H. pylori strain J99 and human stomach AGS cells. Bacterial adhesins affected were identified by overlay assay with immobilized ligands. I-125-radiolabeled F2 served for binding studies to H. pylori and interaction experiments with BabA and SabA. F2 had no cytotoxic effects against H. pylori and AGS cells; but inhibited bacterial binding to human gastric cells. F2 inhibited the binding of BabA and fibronectin-binding adhesin to its specific ligands. Radiolabeled F2 bound non-specifically to different strains of H. pylori; and to BabA deficient mutant. F2 did not lead to subsequent feedback regulation or increased expression of adhesins or virulence factors. From these data the non-specific interactions between F2 and the H. pylori lead to moderate antiadhesive effects.

Keywords
Ribes nigrum L., adhesion, antiadhesion, arabinogalactan protein, BabA, fibronectin, Helicobacter pylori, virulence factors
National Category
Medical Biotechnology (with a focus on Cell Biology (including Stem Cell Biology), Molecular Biology, Microbiology, Biochemistry or Biopharmacy)
Identifiers
urn:nbn:se:umu:diva-90090 (URN)10.3390/molecules19033696 (DOI)000335826800064 ()
Available from: 2014-06-17 Created: 2014-06-17 Last updated: 2018-06-07Bibliographically approved
Plue, J., De Frenne, P., Acharya, K., Brunet, J., Chabrerie, O., Decocq, G., . . . Cousins, S. A. O. (2013). Climatic control of forest herb seed banks along a latitudinal gradient. Global Ecology and Biogeography, 22(10), 1106-1117
Open this publication in new window or tab >>Climatic control of forest herb seed banks along a latitudinal gradient
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2013 (English)In: Global Ecology and Biogeography, ISSN 1466-822X, E-ISSN 1466-8238, Vol. 22, no 10, p. 1106-1117Article in journal (Refereed) Published
Abstract [en]

Aim Seed banks are central to the regeneration strategy of many plant species. Any factor altering seed bank density thus affects plant regeneration and population dynamics. Although seed banks are dynamic entities controlled by multiple environmental drivers, climatic factors are the most comprehensive, but still poorly understood. This study investigates how climatic variation structures seed production and resulting seed bank patterns. Location Temperate forests along a 1900km latitudinal gradient in north-western (NW) Europe. Methods Seed production and seed bank density were quantified in 153 plots along the gradient for four forest herbs with different seed longevity: Geum urbanum, Milium effusum, Poa nemoralis and Stachys sylvatica. We tested the importance of climatic and local environmental factors in shaping seed production and seed bank density. Results Seed production was determined by population size, and not by climatic factors. G.urbanum and M.effusum seed bank density declined with decreasing temperature (growing degree days) and/or increasing temperature range (maximum-minimum temperature). P.nemoralis and S.sylvatica seed bank density were limited by population size and not by climatic variables. Seed bank density was also influenced by other, local environmental factors such as soil pH or light availability. Different seed bank patterns emerged due to differential seed longevities. Species with long-lived seeds maintained constant seed bank densities by counteracting the reduced chance of regular years with high seed production at colder northern latitudes. Main conclusions Seed bank patterns show clear interspecific variation in response to climate across the distribution range. Not all seed banking species may be as well equipped to buffer climate change via their seed bank, notably in short-term persistent species. Since the buffering capacity of seed banks is key to species persistence, these results provide crucial information to advance climatic change predictions on range shifts, community and biodiversity responses.

Place, publisher, year, edition, pages
Wiley-Blackwell, 2013
Keywords
Climate change, interspecific variation, plant-climate interaction, seed longevity, seed production, temperate deciduous forest, temperature
National Category
Ecology Physical Geography Earth and Related Environmental Sciences
Identifiers
urn:nbn:se:umu:diva-81302 (URN)10.1111/geb.12068 (DOI)000323897400002 ()
Available from: 2013-10-15 Created: 2013-10-07 Last updated: 2018-06-08Bibliographically approved
Milbau, A., Shevtsova, A., Osler, N., Mooshammer, M. & Graae, B. J. (2013). Plant community type and small-scale disturbances, but not altitude, influence the invasibility in subarctic ecosystems. New Phytologist, 197(3), 1002-1011
Open this publication in new window or tab >>Plant community type and small-scale disturbances, but not altitude, influence the invasibility in subarctic ecosystems
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2013 (English)In: New Phytologist, ISSN 0028-646X, E-ISSN 1469-8137, Vol. 197, no 3, p. 1002-1011Article in journal (Refereed) Published
Abstract [en]

Little of our knowledge about invasibility comes from arctic and alpine ecosystems, despite increasing plant migration and invasion in those regions. Here, we examine how community type, altitude, and small-scale disturbances affect invasibility in a subarctic ecosystem. Over a period of 4 yr, we studied seedling emergence and establishment in 17 species sown in gaps or undisturbed vegetation in four subarctic community types (Salix scrub, meadow, rich heath, poor heath) along an elevation gradient. Invasibility was lowest in rich heath and highest in Salix scrub. Small disturbances significantly increased the invasibility in most communities, thereby showing the importance of biotic resistance to invasion in subarctic regions. Unexpectedly, invasibility did not decrease with increasing elevation, and it was also not related to summer temperature. Our data suggest that biotic resistance might be more important than abiotic stress for invasibility in subarctic tundra and that low temperatures do not necessarily limit seedling establishment at high altitudes. High elevations are therefore potentially more vulnerable to invasion than was originally thought. Changes in community composition as a result of species migration or invasion are most likely to occur in Salix scrub and meadow, whereas Empetrum-dominated rich heath will largely remain unchanged.

Keywords
arctic and alpine ecosystems, disturbance, elevation, Empetrum hermaphroditum, invasibility, invasion, subarctic, tundra
National Category
Ecology
Identifiers
urn:nbn:se:umu:diva-65904 (URN)10.1111/nph.12054 (DOI)000313266000032 ()
Available from: 2013-03-21 Created: 2013-02-13 Last updated: 2018-06-08Bibliographically approved
De Frenne, P., Graae, B. J., Brunet, J., Shevtsova, A., De Schrijver, A., Chabrerie, O., . . . Verheyen, K. (2012). The response of forest plant regeneration to temperature variation along a latitudinal gradient. Annals of Botany, 109(5), 1037-1046
Open this publication in new window or tab >>The response of forest plant regeneration to temperature variation along a latitudinal gradient
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2012 (English)In: Annals of Botany, ISSN 0305-7364, E-ISSN 1095-8290, Vol. 109, no 5, p. 1037-1046Article in journal (Refereed) Published
Abstract [en]

The response of forest herb regeneration from seed to temperature variations across latitudes was experimentally assessed in order to forecast the likely response of understorey community dynamics to climate warming. Seeds of two characteristic forest plants (Anemone nemorosa and Milium effusum) were collected in natural populations along a latitudinal gradient from northern France to northern Sweden and exposed to three temperature regimes in growth chambers (first experiment). To test the importance of local adaptation, reciprocal transplants were also made of adult individuals that originated from the same populations in three common gardens located in southern, central and northern sites along the same gradient, and the resulting seeds were germinated (second experiment). Seedling establishment was quantified by measuring the timing and percentage of seedling emergence, and seedling biomass in both experiments. Spring warming increased emergence rates and seedling growth in the early-flowering forb A. nemorosa. Seedlings of the summer-flowering grass M. effusum originating from northern populations responded more strongly in terms of biomass growth to temperature than southern populations. The above-ground biomass of the seedlings of both species decreased with increasing latitude of origin, irrespective of whether seeds were collected from natural populations or from the common gardens. The emergence percentage decreased with increasing home-away distance in seeds from the transplant experiment, suggesting that the maternal plants were locally adapted. Decreasing seedling emergence and growth were found from the centre to the northern edge of the distribution range for both species. Stronger responses to temperature variation in seedling growth of the grass M. effusum in the north may offer a way to cope with environmental change. The results further suggest that climate warming might differentially affect seedling establishment of understorey plants across their distribution range and thus alter future understorey plant dynamics.

Place, publisher, year, edition, pages
Oxford University Press, 2012
Keywords
Anemone nemorosa, climate change, common garden, growth chambers, latitudinal gradient, local adaptation, Milium effusum, plant regeneration, range edges, recruitment, seedling establishment, temperature
National Category
Botany
Identifiers
urn:nbn:se:umu:diva-54323 (URN)10.1093/aob/mcs015 (DOI)000301971900020 ()
Available from: 2012-04-24 Created: 2012-04-24 Last updated: 2018-06-08Bibliographically approved
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