| 1. |
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| 2. |
- De Frenne, P., et al.
(författare)
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A latitudinal gradient in seed nutrients of the forest herb Anemone nemorosa
- 2011
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Ingår i: Plant Biology. - : Wiley. - 1435-8603 .- 1438-8677. ; 13:3, s. 493-501
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Tidskriftsartikel (refereegranskat)abstract
- The nutrient concentration in seeds determines many aspects of potential success of the sexual reproductive phase of plants, including the seed predation probability, efficiency of seed dispersal and seedling performance. Despite considerable research interest in latitudinal gradients of foliar nutrients, a similar gradient for seeds remains unexplored. We investigated a potential latitudinal gradient in seed nutrient concentrations within the widespread European understorey forest herb Anemone nemorosa L. We sampled seeds of A. nemorosa in 15 populations along a 1900-km long latitudinal gradient at three to seven seed collection dates post-anthesis and investigated the relative effects of growing degree-hours > 5 degrees C, soil characteristics and latitude on seed nutrient concentrations. Seed nitrogen, nitrogen:phosphorus ratio and calcium concentration decreased towards northern latitudes, while carbon:nitrogen ratios increased. When taking differences in growing degree-hours and measured soil characteristics into account and only considering the most mature seeds, the latitudinal decline remained particularly significant for seed nitrogen concentration. We argue that the decline in seed nitrogen concentration can be attributed to northward decreasing seed provisioning due to lower soil nitrogen availability or greater investment in clonal reproduction. This pattern may have large implications for the reproductive performance of this forest herb as the degree of seed provisioning ultimately co-determines seedling survival and reproductive success.
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| 3. |
- Sarneel, Judith M., et al.
(författare)
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Reading tea leaves worldwide : decoupled drivers of initial litter decomposition mass-loss rate and stabilization
- 2024
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Ingår i: Ecology Letters. - : John Wiley & Sons. - 1461-023X .- 1461-0248. ; 27:5
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Tidskriftsartikel (refereegranskat)abstract
- The breakdown of plant material fuels soil functioning and biodiversity. Currently, process understanding of global decomposition patterns and the drivers of such patterns are hampered by the lack of coherent large-scale datasets. We buried 36,000 individual litterbags (tea bags) worldwide and found an overall negative correlation between initial mass-loss rates and stabilization factors of plant-derived carbon, using the Tea Bag Index (TBI). The stabilization factor quantifies the degree to which easy-to-degrade components accumulate during early-stage decomposition (e.g. by environmental limitations). However, agriculture and an interaction between moisture and temperature led to a decoupling between initial mass-loss rates and stabilization, notably in colder locations. Using TBI improved mass-loss estimates of natural litter compared to models that ignored stabilization. Ignoring the transformation of dead plant material to more recalcitrant substances during early-stage decomposition, and the environmental control of this transformation, could overestimate carbon losses during early decomposition in carbon cycle models.
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| 4. |
- De Frenne, P., et al.
(författare)
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Atmospheric nitrogen deposition on petals enhances seed quality of the forest herb Anemone nemorosa
- 2018
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Ingår i: Plant Biology. - : Wiley. - 1435-8603 .- 1438-8677. ; 20:3, s. 619-626
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Tidskriftsartikel (refereegranskat)abstract
- 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.
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| 5. |
- De Frenne, P, et al.
(författare)
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Significant effects of temperature on the reproductive output of the forest herb Anemone nemorosa L.
- 2010
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Ingår i: Forest Ecology and Management. - : Elsevier BV. - 0378-1127 .- 1872-7042. ; 259:4, s. 809-817
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Tidskriftsartikel (refereegranskat)abstract
- Climate warming is already influencing plant migration in different parts of the world.Numerous modelshave been developed to forecast future plant distributions. Few studies, however, have investigated thepotential effect of warming on the reproductive output of plants. Understorey forest herbs in particular,have received little attention in the debate on climate change impacts.This study focuses on the effect of temperature on sexual reproductive output (number of seeds, seedmass, germination percentage and seedling mass) of Anemone nemorosa L., a model species for slowcolonizing herbaceous forest plants. We sampled seeds of A. nemorosa in populations along a 2400 kmlatitudinal gradient from northern France to northern Sweden during three growing seasons (2005, 2006and 2008). This study design allowed us to isolate the effects of accumulated temperature (GrowingDegree Hours; GDH) from latitude and the local abiotic and biotic environment. Germination and seedsowing trials were performed in incubators, a greenhouse and under field conditions in a forest. Finally,we disentangled correlations between the different reproductive traits of A. nemorosa along thelatitudinal gradient.We found a clear positive relationship between accumulated temperature and seed and seedlingtraits: reproductive output of A. nemorosa improved with increasing GDH along the latitudinal gradient.Seedmass and seedling mass, for instance, increased by 9.7% and 10.4%, respectively, for every 1000 8C hincrease in GDH.Wealso derived strong correlations between several seed and seedling traits both underfield conditions and in incubators. Our results indicate that seed mass, incubator-based germinationpercentage (Germ%Inc) and the output of germinable seeds (product of number of seeds and Germ%Incdivided by 100) from plants grown along a latitudinal gradient (i.e. at different temperature regimes)provide valuable proxies to parameterize key population processes in models.We conclude that (1) climate warming may have a pronounced positive impact on sexualreproduction of A. nemorosa and (2) climate models forecasting plant distributions would benefit fromincluding the temperature sensitivity of key seed traits and population processes.
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| 6. |
- Åberg, Anna, et al.
(författare)
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Helicobacter pylori adapts to chronic infection and gastric disease via ph-responsive baba-mediated adherence
- 2017
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Ingår i: Cell Host and Microbe. - : Elsevier BV. - 1931-3128 .- 1934-6069. ; 21:3, s. 376-389
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Tidskriftsartikel (refereegranskat)abstract
- 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.
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| 7. |
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| 8. |
- De Frenne, Pieter, et al.
(författare)
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An intraspecific application of the leaf-height-seed ecology strategy scheme to forest herbs along a latitudinal gradient
- 2011
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Ingår i: Ecography. - : Wiley. - 0906-7590 .- 1600-0587. ; 34:1, s. 132-140
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Tidskriftsartikel (refereegranskat)abstract
- We measured LHS traits in 41 Anemone nemorosa and 44 Milium effusum populations along a 1900-2300 km latitudinal gradient from N France to N Sweden. We then applied multilevel models to identify the effects of regional (temperature, latitude) and local (soil fertility and acidity, overstorey canopy cover) environmental factors on LHS traits. Both species displayed a significant 4% increase in plant height with every degree northward shift (almost a two-fold plant height difference between the southernmost and northernmost populations). Neither seed mass nor SLA showed a significant latitudinal cline. Temperature had a large effect on the three LHS traits of Anemone. Latitude, canopy cover and soil nutrients were related to the SLA and plant height of Milium. None of the investigated variables appeared to be related to the seed mass of Milium. The variation in LHS traits indicates that the ecological strategy determined by the position of each population in this three-factor triangle is not constant along the latitudinal gradient. The significant increase in plant height suggests greater competitive abilities for both species in the northernmost populations. We also found that the studied environmental factors affected the LHS traits of the two species on various scales: spring-flowering Anemone was affected more by temperature, whereas early-summer flowering Milium was affected more by local and other latitude-related factors. Finally, previously reported cross-species correlations between LHS traits and latitude were generally unsupported by our within-species approach.
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| 9. |
- De Frenne, Pieter, et al.
(författare)
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The response of forest plant regeneration to temperature variation along a latitudinal gradient
- 2012
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Ingår i: Annals of Botany. - : Oxford University Press (OUP). - 0305-7364 .- 1095-8290. ; 109:5, s. 1037-1046
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Tidskriftsartikel (refereegranskat)abstract
- 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.
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| 10. |
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| 11. |
- Graae, Bente Jessen, et al.
(författare)
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The effect of an early-season short-term heat pulse on plant recruitment in the Arctic
- 2009
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Ingår i: Polar Biology. - : Springer Berlin/Heidelberg. - 0722-4060 .- 1432-2056. ; 32:8, s. 1117-1126
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Tidskriftsartikel (refereegranskat)abstract
- Climate change will cause large-scale plant migration. Seedling recruitment constitutes a bottleneck in the migration process but is itself climate-dependent. We tested the effect of warming on early establishment of three Arctic pioneer species, while holding other environmental variables constant. Seeds and bulbils were sown in artificial gaps in dry Arctic tundra and subjected to a 13-day heating of the soil surface by 2-8°C, simulating temperature increases ranging from the general summer warming to heat waves projected to occur more frequently with global warming. All species showed decreased establishment with increasing soil surface temperature. The short-term heat pulse decreased establishment of Polygonum viviparum and Saxifraga cernua, whereas establishment of Cerastium alpinum decreased with temperature due to more permanent natural variation in micro-climate. The treatment effects increased by the quadrat of the temperature increase. Warming and in particular heat waves may result in declining establishment of Arctic plants in dry tundra regions. Electronic supplementary material The online version of this article (doi:10.1007/s00300-009-0608-3) contains supplementary material, which is available to authorized users.
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| 12. |
- Gradskova, Yulia, 1967-, et al.
(författare)
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Post-socialist Revolutions of Intimacy : An Introduction
- 2020
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Ingår i: Sexuality & Culture. - : Springer. - 1095-5143 .- 1936-4822. ; 24:2, s. 359-370
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- During the past decade, the states situated on the territory of the former Soviet Union and in Eastern Europe have made newspaper headlines around the world for topics on gender and sexuality: it seems that each step towards gender equality and inclusive sexual citizenship in the region has been accompanied by counter-actions on different scales. In what way is the present day of appropriate legislation and recent backlash connected to the legacies of regulations of gender relationships, intimacies, and sexualities under state socialism? What role do economic, political, and educational changes that took place in the region in the 1990s play in these developments? And finally, can we speak about certain similarities between discourses on sexuality and intimacy in the “West,” on the one hand, and in post-Soviet and East European countries, on the other? Reflecting on current changes in post-socialist societies, the authors of this special issue give their own answers to these questions.
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| 13. |
- Kable, Mary E., et al.
(författare)
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Host Determinants of Expression of the Helicobacter pylori BabA Adhesin
- 2017
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Ingår i: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322. ; 7
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Tidskriftsartikel (refereegranskat)abstract
- Expression of the Helicobacter pylori blood group antigen binding adhesin A (BabA) is more common in strains isolated from patients with peptic ulcer disease or gastric cancer, rather than asymptomatic colonization. Here we used mouse models to examine host determinants that affect H. pylori BabA expression. BabA expression was lost by phase variation as frequently in WT mice as in RAG2-/- mice that do not have functional B or T cells, and in MyD88-/-, TLR2-/- and TLR4-/- mice that are defective in toll like receptor signaling. The presence of other bacteria had no effect on BabA expression as shown by infection of germ free mice. Moreover, loss of BabA expression was not dependent on Le(b) expression or the capacity of BabA to bind Leb. Surprisingly, gender was the host determinant most associated with loss of BabA expression, which was maintained to a greater extent in male mice and was associated with greater bacterial load. These results suggest the possibility that loss of BabA expression is not driven by adaptive immunity or toll-like receptor signaling, and that BabA may have other, unrecognized functions in addition to serving as an adhesin that binds Le(b).
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| 14. |
- Lemke, Isgard H., et al.
(författare)
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Patterns of phenotypic trait variation in two temperate forest herbs along a broad climatic gradient
- 2015
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Ingår i: Plant Ecology. - : Springer Science and Business Media LLC. - 1385-0237 .- 1573-5052. ; 216:11, s. 1523-1536
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Tidskriftsartikel (refereegranskat)abstract
- 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.
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| 15. |
- Magalhaes, Ana, et al.
(författare)
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Muc5ac gastric mucin glycosylation is shaped by FUT2 activity and functionally impacts Helicobacter pylori binding
- 2016
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Ingår i: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322. ; 6
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Tidskriftsartikel (refereegranskat)abstract
- 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.
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| 16. |
- Plue, Jan, et al.
(författare)
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Climatic control of forest herb seed banks along a latitudinal gradient
- 2013
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Ingår i: Global Ecology and Biogeography. - : Wiley. - 1466-822X .- 1466-8238. ; 22:10, s. 1106-1117
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Tidskriftsartikel (refereegranskat)abstract
- 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.
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| 17. |
- Soudzilovskaia, Nadejda A, et al.
(författare)
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How do bryophytes govern generative recruitment of vascular plants?
- 2011
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Ingår i: New Phytologist. - : Wiley. - 0028-646X .- 1469-8137. ; 190:4, s. 1019-1031
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Tidskriftsartikel (refereegranskat)abstract
- • Interactions between vascular plants and bryophytes determine plant community composition in many ecosystems. Yet, little is known about the importance of interspecific differences between bryophytes with respect to their effects on vascular plants. We compared the extent to which species-specific bryophyte effects on vascular plant generative recruitment depend on the following underlying mechanisms: allelopathy, mechanical obstruction, soil moisture and temperature control. • We sowed 10 vascular plant species into monospecific mats of six chemically and structurally diverse bryophytes, and examined 1-yr seedling recruitment. Allelopathic effects were also assessed in a laboratory phyto-assay. • Although all bryophytes suppressed vascular plant regeneration, there were significant differences between the bryophyte species. The lack of interactions indicated the absence of species-specific adaptations of vascular plants for recruitment in bryophyte mats. Differences between bryophyte species were best explained by alterations in temperature regime under bryophyte mats, mostly by reduced temperature amplitudes during germination. The temperature regime under bryophyte mats was well predicted by species-specific bryophyte cushion thickness. The fitness of established seedlings was not affected by the presence of bryophytes. • Our results suggest that climatically or anthropogenically driven changes in the species' composition of bryophyte communities have knock-on effects on vascular plant populations via generative reproduction.
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