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use of phenological and pollen-production data for interpreting atmospheric birch pollen curves.although aerobiological data are frequently used as a flowering sign in phenological research, airborne pollen counts are influenced by a number of factors affecting pollen curves. a study was made about the reproductive biology of birch and environmental factors influencing its pollen release and transport, in order to achieve a reliable interpretation of betula pollen curves. aerobiological data were recorded in 2002 and 2003 at two sites in nw spain and phenological observations were carried ...200718247464
bpmads4 has a central role in inflorescence initiation in silver birch (betula pendula).acceleration of flowering would be beneficial for breeding trees with a long juvenile phase; conversely, inhibition of flowering would prevent the spread of transgenes from the genetically modified trees. we have previously isolated and characterized several mads genes from silver birch (betula pendula roth). in this study, we investigated the more detailed function of one of them, bpmads4, a member of the apetala1/fruitfull group of mads genes. the expression of bpmads4 starts at very early sta ...200718251933
temperature dependency of bark photosynthesis in beech (fagus sylvatica l.) and birch (betula pendula roth.) trees.temperature dependencies of stem dark respiration (r(d)) and light-driven bark photosynthesis (a(max)) of two temperate tree species (fagus sylvatica and betula pendula) were investigated to estimate their probable influence on stem carbon balance. stem r(d) was found to increase exponentially with increasing temperatures, whereas a(max) levelled off or decreased at the highest temperatures chosen (35-40 degrees c). accordingly, a linear relationship between respiratory and assimilatory metaboli ...200718182432
plant community influences on soil microfungal assemblages in boreal mixed-wood forests.we studied the relationships between assemblages of soil microfungi and plant communities in the southern boreal mixed-wood forests of quebec. sampling took place in 18,100 m2 plots from an existing research site. plots were separated into three categories based on dominant overstory tree species: (i) trembling aspen, (ii) white birch and (iii) a mixture of white spruce and balsam fir. within each plot a 1 m2 subplot was established in which the understory herbaceous layer was surveyed and soil ...200717883027
anti-ice nucleation activity in xylem extracts from trees that contain deep supercooling xylem parenchyma cells.boreal hardwood species, including japanese white birch (betula platyphylla sukat. var. japonica hara), japanese chestnut (castanea crenata sieb. et zucc.), katsura tree (cercidiphyllum japonicum sieb. et zucc.), siebold's beech (fagus crenata blume), mulberry (morus bombycis koidz.), and japanese rowan (sorbus commixta hedl.), had xylem parenchyma cells (xpcs) that adapt to subfreezing temperatures by deep supercooling. crude extracts from xylem in all these trees were found to have anti-ice nu ...200717936742
simultaneous determination of betulin and betulinic acid in white birch bark using rp-hplc.a simple procedure is described for the simultaneous extraction and determination of betulin and betulinic acid in white birch bark. the extraction was checked using different solvents: dichloromethane, ethyl acetate, acetone, chloroform, methanol and 95% ethanol (aqueous solution, v/v). it was found 95% ethanol was a good extraction solvent that allowed extraction of triterpenoid with a highest content. separation was achieved on a reversed phase c(18) column with acetonitrile-water 86:14 (v/v) ...200717084057
northern environment predisposes birches to ozone damage.ozone sensitivity of silver birch ( betula pendula roth) has been thoroughly investigated since early 1990's in finland. in our long-term open-field experiments the annual percentage reduction in basal diameter and stem volume increment were the best non-destructive growth indicators for ozone impact when plotted against aotx. remarkable differences in defence strategies, stomatal conductance, and defence compounds (phenolics), clearly indicate that external exposure indices are ineffective for ...200716865657
assessment of metal availability to vegetation (betula pendula) in pb-zn ore concentrate residues with different features.in this work, characterisation of several ore concentrate remains from an abandoned pb-zn mining factory was performed determining chemical and physical properties such as ph, organic carbon content, particle size distribution, total heavy metal content (pb, zn, cu, as and cd) as well as mineralogical composition which showed, in most cases, the oxidization of the parent ore material (mostly galena: pbs and sphalerite: zns) to more mobile fractions as anglesite (pbso(4)) and goslarite (znso(4)). ...200716777289
cytokinin signaling regulates cambial development in poplar.although a substantial proportion of plant biomass originates from the activity of vascular cambium, the molecular basis of radial plant growth is still largely unknown. to address whether cytokinins are required for cambial activity, we studied cytokinin signaling across the cambial zones of 2 tree species, poplar (populus trichocarpa) and birch (betula pendula). we observed an expression peak for genes encoding cytokinin receptors in the dividing cambial cells. we reduced cytokinin levels endo ...200819064928
phylogeny of chitinases and its implications for estimating horizontal gene transfer from chitinase-transgenic silver birch (betula pendula).chitinases are hydrolytic enzymes that have been employed in biotechnology in attempts to increase plants' resistance against fungal pathogens. genetically modified plants have given rise to concerns of the spreading of transgenes into the environment through vertical or horizontal gene transfer (hgt). in this study, chitinase-like sequences from silver birch (betula pendula) est-libraries were identified and their phylogenetic relationships to other chitinases were studied. phylogenetic analyse ...200819081010
the bark of betula platyphylla var. japonica inhibits the development of atopic dermatitis-like skin lesions in nc/nga mice.the bark of betula platyphylla sukat. var. japonica hara (asian white birch, awb) is one of the herbs used in eastern countries for the treatment of various inflammatory diseases including atopic dermatitis (ad). the present study was performed to examine if and how the bark of awb inhibits the development of ad-like skin lesions in nc/nga mice induced by repeated application of picryl chloride (pc). with this aim, we examined the skin symptom severity, itching behavior, serum immunoglobulin (ig ...200818191513
protease activity of allergenic pollen of cedar, cypress, juniper, birch and ragweed.pollen is an important trigger of allergic rhinitis, conjunctivitis, and/or asthma, and an exacerbating factor in atopic dermatitis. although it is proposed that protease activity from allergen sources, such as mites, enhances allergenicity, little information is available on that from relevant allergenic pollens such as japanese cedar and japanese cypress pollens, which are the major cause of pollinosis in japan.200818209508
spinning of a gigantic bundle of hollow fibrils by a spirally moving higher plant protoplast.a unique fiber spinning was found in protoplasts from white birch (betula platyphylla) leaves under an acidic medium containing high concentration of ca(2+). after expanding from 10 to 100 microm in diameter under the culture condition, the protoplast started secreting a gigantic fiber while moving in a spiral way. real time video analyses elucidated that the orientation, rate and pattern of the motion were directed due to the inverse force of the fiber spinning. moreover, observation using seve ...200818214528
fungi, including ophiostoma karelicum sp. nov., associated with scolytus ratzeburgi infesting birch in finland and russia.several elm-infesting bark beetles belonging to the genus scolytus (coleoptera: scolytinae) are vectors of ophiostoma spp., most notably the dutch elm disease fungi. a related bark beetle species, scolytus ratzeburgi, is known to infest birch in various parts of europe, but it is unknown whether fungi are associated with this beetle. the aim of this study was to identify several fungal species isolated from s. ratzeburgi. beetles and their galleries were collected from betula pendula at three di ...200818656542
synthesis of beta-o-4-type artificial lignin polymers and their analysis by nmr spectroscopy.we describe the synthesis and nmr spectroscopic analysis of three artificial lignin polymers containing only the beta-o-4 substructure: syringyl-type homopolymer, p-hydroxyphenyl-type homopolymer and guaiacyl/syringyl-type heteropolymer. using gel permeation chromatography, the weight-average degree of polymerization (dp(w)) of the three polymers was determined as 19.2, 38.6, and 13.9, respectively. the polymers were prepared based on the synthetic methodology of guaiacyl-type homopolymer, and w ...200818688492
the allergen profile of beech and oak pollen.beech and oak pollen are potential allergen sources with a world-wide distribution.200818754759
carotenoids in a food chain along a pollution gradient.carotenoids are synthesized by plants, therefore insects and birds must obtain them from their diet. they function in pigmentation and as antioxidants. we studied the carotenoid profiles in a model food chain (plant-insect-bird) in an air pollution gradient to find out whether heavy metal pollution affects the transfer of carotenoids across the trophic levels. birch leaves showed higher beta-carotene and, one of the birch species (betula pendula), higher total carotenoids levels in the polluted ...200818789813
the significance of ectomycorrhizas in chemical quality of silver birch foliage and above-ground insect herbivore performance.we tested whether the ectomycorrhizal (ecm) infection level of roots of silver birch (betula pendula) affects performance of above-ground insect herbivores by increasing available plant biomass, by enhancing availability of nutrients, or by modifying concentration of defense compounds, i.e., phenolics, in birch foliage. insect performance was determined for a phloem-feeding generalist (lygus rugulipennis, the european tarnished plant bug), a phloem-feeding specialist (calaphis flava, the birch a ...200818797972
the seeds quality of betula pndula roth and betula oscura kotula from semi-natural and anthropogenic habitats.this research presents the results of the study of seeds quality of two polish native species of the genus betula l. (betula pendula roth and betula obscura kotula), growing on the semi-natural (low human activities) and anthropogenic (high human activities) habitats. in this study the generative phase has been investigated to find differences between studied taxa and try to find out why population of b. obscura is very rare. in this research we have checked the quality of the seeds from b. obsc ...200818817246
increasing litter species richness reduces variability in a terrestrial decomposer system.debate on the relationship between diversity and stability has been driven by the recognition that species loss may influence ecosystem properties and processes. we conducted a litterbag experiment in the scottish highlands, united kingdom, to examine the effects of altering plant litter diversity on decomposition, microbial biomass, and microfaunal abundance. the design of treatments was fully factorial and included five species from an upland plant community (silver birch, betula pendula; scot ...200818831186
concentrations of foliar quercetin in natural populations of white birch (betula pubescens) increase with latitude.we investigated latitudinal and regional variations in the composition and concentrations of foliar flavonoids and condensed tannins in wild populations of white birch (betula pubescens ehrh) in a large climatic transect in finland. concentrations of quercetin derivatives were correlated positively with latitude. by contrast, the concentrations of apigenin and naringenin derivatives were correlated negatively with latitude. these compound-specific latitudinal gradients compensated each other, re ...200818946705
density and composition of an insect population in a field trial of chitinase transgenic and wild-type silver birch (betula pendula) clones.fifteen silver birch (betula pendula roth) lines carrying a sugar beet chitinase iv gene and eight wild-type birch clones were grown in a field trial. the composition and density of the insect population and the leaf damage caused by insects were monitored and compared between transgenic and wild-type trees. the most abundant insect group in all trees was aphids, and the variation in total insect densities was mainly explained by the variation in aphid densities. insect densities were generally ...200819161703
a comparison of phenological models of leaf bud burst and flowering of boreal trees using independent observations.we compared and tested thermal time, sequential, parallel and flexible phenological models of leaf bud burst in birch (betula pendula roth. and b. pubescens ehrh.) and flowering in bird cherry (prunus padus l.) and rowan (sorbus aucuparia l.). we used phenological records from oulainen-ohineva (64 degrees 13' n, 24 degrees 53' e) in central finland from 1953 to 2002 to estimate model parameters. we tested the models with data collected in all but six years between 1896 and 2002 in southern and c ...200819193570
forest microsite effects on community composition of ectomycorrhizal fungi on seedlings of picea abies and betula pendula.niche differentiation in soil horizons, host species and natural nutrient gradients contribute to the high diversity of ectomycorrhizal fungi in boreal forests. this study aims at documenting the diversity and community composition of ectomycorrhizal fungi of norway spruce (picea abies) and silver birch (betula pendula) seedlings in five most abundant microsites in three estonian old-growth forests. undisturbed forest floor, windthrow mounds and pits harboured more species than brown- and white- ...200818266759
stomatal characteristics and infection biology of pyrenopeziza betulicola in betula pendula trees grown under elevated co2 and o3.two silver birch clones were exposed to ambient and elevated concentrations of co(2) and o(3), and their combination for 3 years, using open-top chambers. we evaluated the effects of elevated co(2) and o(3) on stomatal conductance (g(s)), density (sd) and index (si), length of the guard cells, and epidermal cell size and number, with respect to crown position and leaf type. the relationship between the infection biology of the fungus (pyrenopeziza betulicola) causing leaf spot disease and stomat ...200818289750
diversity of predominant endophytic bacteria in european deciduous and coniferous trees.the diversity of endophytic bacteria residing in root, stem, and leaf tissues was examined in coniferous and deciduous tree species, scots pine (pinus sylvestris l.), silver birch (betula pendula roth), and rowan (sorbus aucuparia l.). using cultivation-dependent and -independent analyses, the bacterial communities were observed to be significantly different in the belowground (roots and rhizosphere) and aboveground (leaves and stems) samples of the respective host trees. no significant differen ...200818388988
supercritical fluid extraction of amino acids from birch (betula pendula roth) leaves and their liquid chromatographic determination with fluorimetric detection.a method for supercritical fluid extraction (sfe) of amino acids was adapted and optimal experimental conditions were selected for a matrix consisting of dry leaves. the matrix-dependent sfe method uses a mixture of meoh-h(2)o-acetonitrile (10:10:1 v/v/v) as a modifier (0.5 ml in situ, 300 mul on-line) at 70 degrees c and 40 mpa and no hcl is needed as an entrainer. the amino acids were quantified using high-performance liquid chromatography with fluorimetric detection (hplc/fld) after gradient ...200818398864
betulinic acid suppresses constitutive and tnfalpha-induced nf-kappab activation and induces apoptosis in human prostate carcinoma pc-3 cells.development of chemoresistance in androgen-refractory prostate cancer cells is partly due to constitutive activation of rel/nf-kappab transcription factors that regulate several cell survival and anti-apoptotic genes. in this study we examined whether betulinic acid (beta), a pentacyclic triterpene from the bark of white birch, is effective in inhibiting nf-kappab expression in androgen-refractory human prostate cancer cells exhibiting high constitutive nf-kappab expression. treatment of pc-3 ce ...200818444250
involvement of cbf transcription factors in winter hardiness in birch.cold acclimation of plants involves extensive reprogramming of gene expression. in arabidopsis (arabidopsis thaliana), three cold-inducible transcriptional activators designated cbf1 to -3/dreb1a to -c have been shown to play an important regulatory role in this acclimation process. similarly to arabidopsis, boreal zone trees can increase their freezing tolerance (ft) in response to low temperature during the growing season. however, maximal ft of these trees requires short daylength-induced dor ...200818467468
chemical constituents of stereum subtomentosum and two other birch-associated basidiomycetes: an interspecies comparative study.metabolites of the wood-rotting fungus stereum subtomentosum pouzar (basidiomycetes, order russulales, family stereaceae) occurring on birch (betula pendula roth) trees were phytochemically investigated for the first time. three main metabolite chemotypes present in meoh extracts of the fruit bodies, viz. steroids, fatty acids, and water-soluble sugars, were fractionated, isolated, and identified by 1d/2d nmr-spectroscopic analyses, nmr data comparisons, and chemical correlations combined with g ...200818493960
effects of light intensity and duration on leaf hydraulic conductance and distribution of resistance in shoots of silver birch (betula pendula).variation in leaf hydraulic conductance (k(l)) and distribution of resistance in response to light intensity and duration were examined in shoots of silver birch (betula pendula roth). k(l) was determined on detached shoots using the evaporative flux method (transpiration was measured with a porometer and water potential drop with a pressure chamber). although k(l) depended on light duration per se, its dynamics was largely determined by leaf temperature (t(l)). both upper-crown leaves and branc ...200818513374
toward an improved model of maple sap exudation: the location and role of osmotic barriers in sugar maple, butternut and white birch.two theories have been proposed to explain how high positive pressures are developed in sugar maple stems when temperatures fluctuate around freezing. the milburn-o'malley theory proposes that pressure development is purely physical and does not require living cells or sucrose. the osmotic theory invokes the involvement of living cells and sucrose to generate an osmotic pressure difference between fibers and vessels, which are assumed to be separated by an osmotic barrier. we analyzed wood of ac ...200818519246
high aromatic ring-cleavage diversity in birch rhizosphere: pah treatment-specific changes of i.e.3 group extradiol dioxygenases and 16s rrna bacterial communities in soil.genes encoding key enzymes of catabolic pathways can be targeted by dna fingerprinting to explore genetic degradation potential in pristine and polluted soils. we performed a greenhouse microcosm experiment to elucidate structural and functional bacterial diversity in polyaromatic hydrocarbon (pah)-polluted soil and to test the suitability of birch (betula pendula) for remediation. degradation of pahs was analysed by high-performance liquid chromatography, dna isolated from soil amplified and fi ...200818563190
element mobility and partitioning along a soil acidity gradient in central ontario forests, canada.the potential environmental risk posed by metals in forest soils is typically evaluated by modeling metal mobility using soil-solution partitioning coefficients (k(d)), although such information is generally restricted to a few well-studied metals. soil-solution partitioning coefficients were determined for 17 mineral elements (al, as, be, ba, ca, cr, cu, fe, ga, k, li, mg, rb, sr, tl, u and v) in a-horizon (0-5 cm) soil at 46 forested sites that border the precambrian shield in central ontario, ...200818058024
two new phenylbutanoids from inner bark of betula pendula.two phenylbutanoids, 7-{3r-[(4-hydroxyphenyl)butyl] beta-glucopyranosid-o-6-yl} 4-o-beta-glucopyranosylvanillin and 3-beta-glucopyranosyloxy-1-(4-hydroxyphenyl)-butanone were isolated from an aqueous methanol extract of the inner bark of betula pendula. their structures were determined by nmr spectroscopy and mass spectrometry. the complete assignment of proton and carbon signals was achieved by 1d and 2d nmr experiments: selective 1d tocsy, hsqc, hmbc and dqf-cosy.200818098157
cadmium accumulation and its effect on the in vitro growth of woody fleabane and mycorrhized white birch.the effect of cd on woody fleabane (dittrichia viscosa (l.) greuter) and white birch (betula celtiberica rothm. & vasc.) was examined. woody fleabane and white birch were grown in vitro in murashige, t., skoog, f., [1962. a revised medium for rapid growth and bioassays with tobacco tissue cultures. physiol. plant. 15, 473-479] (ms) plus cd (10 mg cd kg(-1)) and except for root length in white birch, plant development was inhibited when cd was added. cd accumulation in above-ground tissues showed ...200817719154
[on the competition among discrete-structured populations: a matrix model for population dynamics of woodreed and birch growing together].presented is a synthesis of field, theoretical and modelling studies on joint dynamics of two species--common birch (betula pendula roth) and wood small reed (calamagrostis epigeios (l.) roth)--overgrowing a spruce forest clear-cut. a nonlinear matrix model for population dynamics of two species, which both possess non-trivial population structures and compete for a resource in common was developed as an expansion of the linear models for single-species, age-stage-structured population dynamics. ...200819140335
pollen allergenic potential nature of some trees species: a multidisciplinary approach using aerobiological, immunochemical and hospital admissions data.trees are considered producers of allergenic pollen. the aims of this work were to characterize the aerobiology of the platanus, acer, salix, quercus, betula and populus pollen, linking it with monthly emergency hospital admissions and to identify the different reactivity levels in sensitized patients. this information would be of great importance to evaluate the convenience of changing the inventory of pollen producer trees related to the risk of allergenic reactions. the study was conducted in ...200919147130
near-ambient ozone concentrations reduce the vigor of betula and populus species in finland.in this review the main growth responses of finnish birch (betula pendula, b. pubescens) and aspen species (populus tremula and p. tremuloides x p. tremula) are correlated with ozone exposure, indicated as the aot40 value. data are derived from 23 different laboratory, open-top chamber, and free-air fumigation experiments. our results indicate that these tree species are sensitive to increasing ozone concentrations, though high intraspecific variation exists. the roots are the most vulnerable ta ...200920175439
rising atmospheric co2 concentration partially masks the negative effects of elevated o3 in silver birch (betula pendula roth).this review summarizes the main results from a 3-year open top chamber experiment, with two silver birch (betula pendula roth) clones (4 and 80) where impacts of 2x ambient [co2] (ec) and [o3] (eo) and their combination (ec + eo) were examined. growth, physiology of the foliage and root systems, crown structure, wood properties, and biological interactions were assessed to understand the effects of a future climate on the biology of silver birch. the clones displayed great differences in their r ...200920175440
ophiostoma denticiliatum sp. nov. and other ophiostoma species associated with the birch bark beetle in southern norway.ophiostomatoid fungi were isolated from scolytus ratzeburgi infesting betula pendula and b. pubescens in norway. fungi were identified based on morphology, dna sequence comparison for two gene regions and phylogenetic analyses. the most abundant fungus was ophiostoma karelicum, suggesting a specific relationship between the fungus, the vector insect and the host tree. our results suggest that o. karelicum occurs across the geographic range of s. ratzeburgi and its close relatedness to the dutch ...200920198157
characterization of pr-10 genes from eight betula species and detection of bet v 1 isoforms in birch pollen.bet v 1 is an important cause of hay fever in northern europe. bet v 1 isoforms from the european white birch (betula pendula) have been investigated extensively, but the allergenic potency of other birch species is unknown. the presence of bet v 1 and closely related pr-10 genes in the genome was established by amplification and sequencing of alleles from eight birch species that represent the four subgenera within the genus betula. q-tof lc-mse was applied to identify which pr-10/bet v 1 genes ...200919257882
identification and isolation of pharmacologically active triterpenes in betuale cortex, betula pendula roth., betulaceae.betulae cortex, betula pendula roth., betulaceae, comprise triterpene substances which are confirmed to posses very important pharmacological activities such as anti-inflammatory, anticancer and antiviral. in this study, extraction of triterpene substances from both, inner and external birch bark was carried out and after that qualitative analysis on betulin, betulinic acid, oleanolic acid and lupeol was performed by method of thin layer chromatography. by this separation method, applying system ...200919284392
fire drives transcontinental variation in tree birch defense against browsing by snowshoe hares.fire has been the dominant disturbance in boreal america since the pleistocene, resulting in a spatial mosaic in which the most fire occurs in the continental northwest. spatial variation in snowshoe hare (lepus americanus) density reflects the fire mosaic. because fire initiates secondary forest succession, a fire mosaic creates variation in the abundance of early successional plants that snowshoe hares eat in winter, leading to geographic variation in hare density. we hypothesize that fire is ...200919422319
variation in host specificity and gene content in strains from genetically isolated lineages of the ectomycorrhizal fungus paxillus involutus s. lat.ectomycorrhizal fungi are known to vary in host range. some fungi can enter into symbiosis with multiple plant species, while others have restricted host ranges. the aim of this study was to examine variation in host specificity among strains from the basidiomycete paxillus involutus s. lat. recent studies have shown that this fungus consists of at least four genetically isolated lineages, phylogenetic species (ps) i (which corresponds to the morphological species paxillus obscurosporus), ps ii ...200919452174
interactive effect of elevated temperature and o3 on antioxidant capacity and gas exchange in betula pendula saplings.we studied the effects of slightly elevated temperature (t), o(3) concentration (o(3)) and their combination (t + o(3)) on the antioxidant defense, gas exchange and total leaf area of betula pendula saplings in field conditions. during the second year of the experiment, t enhanced the total leaf area, net photosynthesis (p (n)) and maximum capacity of carboxylation, redox state of ascorbate and total antioxidant capacity in the apoplast. o(3) did not affect the total leaf area, but p (n) was sli ...200919484475
life-history strategies affect aphid preference for yellowing leaves.according to the nutrient-translocation hypothesis, yellowing tree leaves are colonized by aphids at the end of the growing season owing to improved availability of nutrients in the phloem sap after chlorophyll degradation. we measured aphid densities on potted betula pendula seedlings in a field site where a small proportion of foliage rapidly turned yellow before normal autumn coloration as a consequence of root anoxia. the number of adults and nymphs of the birch-feeding specialist aphids euc ...200919535364
solar ultraviolet radiation alters alder and birch litter chemistry that in turn affects decomposers and soil respiration.solar ultraviolet (uv)-a and uv-b radiation were excluded from branches of grey alder (alnus incana) and white birch (betula pubescens) trees in a field experiment. leaf litter collected from these trees was used in microcosm experiments under laboratory conditions. the aim was to evaluate the effects of the different uv treatments on litter chemical quality (phenolic compounds, c, n and lignin) and the subsequent effects of these changes on soil fauna and decomposition processes. we measured th ...200919597848
rubisco in planta kcat is regulated in balance with photosynthetic electron transport.site turnover rate (k(cat)) of rubisco was measured in intact leaves of different plants. potato (solanum tuberosum l.) and birch (betula pendula roth.) leaves were taken from field-growing plants. sunflower (helianthus annuus l.), wild type (wt), rubisco-deficient (-rbc), fnr-deficient (-fnr), and cyt b(6)f deficient (-cbf) transgenic tobacco (nicotiana tabacum l.) were grown in a growth chamber. rubisco protein was measured with quantitative sds-page and fnr protein content with quantitative i ...200919661266
growth of frankia strains in leaf litter-amended soil and the rhizosphere of a nonactinorhizal plant.the ability of frankia strains to grow in the rhizosphere of a nonactinorhizal plant, betula pendula, in surrounding bulk soil and in soil amended with leaf litter was analyzed 6 weeks after inoculation of pure cultures by in situ hybridization. growth responses were related to taxonomic position as determined by comparative sequence analysis of nifh gene fragments and of an actinomycetes-specific insertion in domain iii of the 23s rrna gene. phylogenetic analyses confirmed the basic classificat ...200919678845
assessment of uv biological spectral weighting functions for phenolic metabolites and growth responses in silver birch seedlings.in research concerning stratospheric ozone depletion, action spectra are used as biological spectral weighting functions (bswfs) for describing the effects of uv radiation on plant responses. our aim was to evaluate the appropriateness of six frequently used bswfs that differ in effectiveness with increasing wavelength. the evaluation of action spectra was based on calculating the effective uv radiation doses according to 1-2) two formulations of the generalized plant action spectrum, 3) a spect ...200919682323
effects of sugar beet chitinase iv on root-associated fungal community of transgenic silver birch in a field trial.heterogenous chitinases have been introduced in many plant species with the aim to increase the resistance of plants to fungal diseases. we studied the effects of the heterologous expression of sugar beet chitinase iv on the intensity of ectomycorrhizal (ecm) colonization and the structure of fungal communities in the field trial of 15 transgenic and 8 wild-type silver birch (betula pendula roth) genotypes. fungal sequences were separated in denaturing gradient gel electrophoresis and identified ...200919697057
phenolic compounds in ectomycorrhizal interaction of lignin modified silver birch.the monolignol biosynthetic pathway interconnects with the biosynthesis of other secondary phenolic metabolites, such as cinnamic acid derivatives, flavonoids and condensed tannins. the objective of this study is to evaluate whether genetic modification of the monolignol pathway in silver birch (betula pendula roth.) would alter the metabolism of these phenolic compounds and how such alterations, if exist, would affect the ectomycorrhizal symbiosis.200919788757
interactions of ectomycorrhizas and above-ground insect herbivores on silver birch. 200919794863
low moisture availability inhibits the enhancing effect of increased soil temperature on net photosynthesis of white birch (betula papyrifera) seedlings grown under ambient and elevated carbon dioxide concentrations.white birch (betula papyrifera marsh.) seedlings were grown under two carbon dioxide concentrations (ambient: 360 micromol mol(-1) and elevated: 720 micromol mol(-1)), three soil temperatures (5, 15 and 25 degrees c initially, increased to 7, 17 and 27 degrees c, respectively, 1 month later) and three moisture regimes (low: 30-40%; intermediate: 45-55% and high: 60-70% field water capacity) in greenhouses. in situ gas exchange and chlorophyll fluorescence were measured after 2 months of treatmen ...200919797245
betulin elicits anti-cancer effects in tumour primary cultures and cell lines in vitro.betulin is a pentacyclic triterpene found in many plant species, among others, in white birch bark. the aim of the study was in vitro characterization of the anticancer activity of betulin in a range of human tumour cell lines (neuroblastoma, rhabdomyosarcoma-medulloblastoma, glioma, thyroid, breast, lung and colon carcinoma, leukaemia and multiple myeloma), and in primary tumour cultures isolated from patients (ovarian carcinoma, cervical carcinoma and glioblastoma multiforme). in this study, w ...200919821831
[the dynamics of phenolic compounds and soluble sugars in the leaves of the silver birch (betula pendula roth) after defoliation and their significance in entomological plant resistance].the dynamics of phenolic compounds, flavonols, catechines, tannins, and soluble sugars in the leaves of the silver birch betula pendula roth after strong (75%) and total (100%) artificial defoliation was studied. it was shown that the flavonol content in the leaves did not change after strong and total defoliation, while the amount of tannins did not change during the first 15 days but increased later on 1 and 2 years after 75% and 100% defoliation. the catechine content did not change during th ...200919894597
effect of tree species and mycorrhizal colonization on the archaeal population of boreal forest rhizospheres.group 1.1c crenarchaeota are the predominating archaeal group in acidic boreal forest soils. in this study, we show that the detection frequency of 1.1c crenarchaeotal 16s rrna genes in the rhizospheres of the boreal forest trees increased following colonization by the ectomycorrhizal fungus paxillus involutus. this effect was very clear in the fine roots of pinus sylvestris, picea abies, and betula pendula, the most common forest trees in finland. the nonmycorrhizal fine roots had a clearly dif ...200918978075
optimization of ultrasonic-assisted extraction (uae) of betulin from white birch bark using response surface methodology.betulin is an abundant naturally occurring triterpene, which makes it a potentially important raw material for a precursor of biologically active compounds. the objective of the current study was to determine the optimum uae conditions for betulin from b. papyfera bark. the optimum conditions were evaluated with fractional factorial design and optimized using response surface methodology. high yields of betulin were observed from white birch bark by uae technology. the solvent concentration and ...200919110462
low soil temperature inhibits the effect of high nutrient supply on photosynthetic response to elevated carbon dioxide concentration in white birch seedlings.to investigate the interactive effects of soil temperature (t(soil)) and nutrient availability on the response of photosynthesis to elevated atmospheric carbon dioxide concentration ([co(2)]), white birch (betula papyrifera marsh.) seedlings were exposed to ambient (360 micromol mol(-1)) or elevated (720 micromol mol(-1)) [co(2)], three t(soil) (5, 15 and 25 degrees c initially, increased to 7, 17 and 27 degrees c, respectively, 1 month later) and three nutrient regimes (4/1.8/3.3, 80/35/66 and ...201020007132
determination of de novo and pool emissions of terpenes from four common boreal/alpine trees by 13co2 labelling and ptr-ms analysis.boreal forests emit a large amount of monoterpenes into the atmosphere. traditionally these emissions are assumed to originate as evaporation from large storage pools. thus, their diurnal cycle would depend mostly on temperature. however, there is indication that a significant part of the monoterpene emission would originate directly from de novo synthesis. by applying 13co2 fumigation and analyzing the isotope fractions with proton transfer reaction mass spectrometry (ptr-ms) and classical gc-m ...201020040067
acc oxidase genes expressed in the wood-forming tissues of loblolly pine (pinus taeda l.) include a pair of nearly identical paralogs (nips).1-aminocyclopropane-1-carboxylate (acc) oxidase catalyzes the final reaction of the ethylene biosynthetic pathway, converting the unusual cyclic amino acid, acc, into ethylene. past studies have shown a possible link between ethylene and compression wood formation in conifers, but the relationship has received no more than modest study at the gene expression level. in this study, a cdna clone encoding a putative acc oxidase, ptaco1, was isolated from a cdna library produced using mrna from ligni ...201020053371
foliar methyl salicylate emissions indicate prolonged aphid infestation on silver birch and black alder.it is well documented that when plants are damaged by insects they respond by emitting a range of volatile organic compounds (vocs). while there have been numerous reports concerning vocs induced by chewing herbivores, there are relatively few studies detailing the vocs induced by aphid feeding. the effects of aphid feeding on vocs emitted by boreal forest trees have been particularly neglected. herbivore-induced vocs have relevance to direct and indirect plant defence and atmospheric chemistry. ...201020097686
differential gene expression in senescing leaves of two silver birch genotypes in response to elevated co2 and tropospheric ozone.long-term effects of elevated co(2) and o(3) concentrations on gene expression in silver birch (betula pendula roth) leaves were studied during the end of the growing season. two birch genotypes, clones 4 and 80, with different ozone growth responses, were exposed to 2x ambient co(2) and/or o(3) in open-top chambers (otcs). microarray analyses were performed after 2 years of exposure, and the transcriptional profiles were compared to key physiological characteristics during leaf senescence. ther ...201020132521
photosynthetic characteristics in genetically modified sense-rbcs silver birch lines.transgenic silver birch lines carrying extra copies of endogenous small subunit of rubisco (rbcs)-gene under 35s camv promoter were used to study the carbon use efficiency of silver birch (betula pendula roth). a five week greenhouse experiment was carried out with four transgenic lines, r3.2, r7.2, e5 and e25, and their corresponding wild types (wt). the first fully developed leaves were used for analyses. three of the produced lines, r3.2, e5 and e25, differed from the wt lines. line r3.2 show ...201020171755
changes in pelagic bacteria communities due to leaf litter addition.in many limnetic systems, the input of allochthonous organic matter, e.g., leaf litter, is a substantial source of dissolved organic carbon (doc) for pelagic bacteria, especially in fall and winter when autochthonous doc production is low. however, relatively little is known about community changes of pelagic lake bacteria due to leaf litter input which includes both the release of leaf leachates and microorganisms from the leaf litter into the surrounding water. therefore, we have experimentall ...201020198369
birch (betula spp.) leaves adsorb and re-release volatiles specific to neighbouring plants--a mechanism for associational herbivore resistance?plant-emitted semi-volatile compounds have low vaporization rates at 20-25 degrees c and may therefore persist on surfaces such as plant foliage. the passive adsorption of arthropod-repellent semi-volatiles to neighbouring foliage could convey associational resistance, whereby a plant's neighbours reduce damage caused by herbivores. we found that birch (betula spp.) leaves adsorb and re-release the specific arthropod-repelling c(15) semi-volatiles ledene, ledol and palustrol produced by rhododen ...201020298484
impact of hemicellulose pre-extraction for bioconversion on birch kraft pulp properties.the combination of hemicellulose extraction with chemical pulping processes is one approach to generate a sugar feedstock amenable to biochemical transformation to fuels and chemicals. extractions of hemicellulose from silver birch (betula pendula) wood chips using either water or kraft white liquor (naoh, na(2)s, and na(2)co(3)) were performed under conditions compatible with kraft pulping, using times ranging between 20 and 90 min, temperatures of 130-160 degrees c, and effective alkali (ea) c ...201020378336
forage quantity, quality and depletion as scale-dependent mechanisms driving habitat selection of a large browsing herbivore.1. mechanisms that affect the spatial distribution of animals are typically scale-dependent and may involve forage distribution. forage quality and quantity are often inversely correlated and a much discussed trade-off is whether or not to select for high-quality forage at the expense of forage abundance. this discussion has rarely involved scale-dependence or been applied to northern browsing herbivores. at small spatial scales, browsers are assumed to select for the best quality forage. but, a ...201020443990
pollen enzymes degrade human tear fluid and conjunctival cells: an approach to understanding seasonal non-allergic conjunctivitis.during pollen seasons, allergy-like symptoms can be observed in proven non-allergy sufferers. pollen enzymes are thought to be responsible for conjunctival irritation. we investigated the influence of the well-known aggressive pollen species hazelnut (corylus avellana) and birch pollen (betula pendula) on both human tear fluid and conjunctival cell cultures. this study is an approach to seasonal non-allergic conjunctivitis (snac) syndrome.201020502029
effects of solar uv-a and uv-b radiation on gene expression and phenolic accumulation in betula pendula leaves.ultraviolet (uv) radiation is an important environmental factor for plant communities; however, plant responses to solar uv are not fully understood. here, we report differential effects of solar uv-a and uv-b radiation on the expression of flavonoid pathway genes and phenolic accumulation in leaves of betula pendula roth (silver birch) seedlings grown outdoors. plants were exposed for 30 days to six uv treatments created using three types of plastic film. epidermal flavonoids measured in vivo d ...201020519675
seasonal fluctuations in leaf phenolic composition under uv manipulations reflect contrasting strategies of alder and birch trees.seasonal variation in leaf phenolic composition may be important for acclimation of plants to seasonal changes in their biotic and abiotic environment. for a realistic assessment of how plants respond to solar uv-b (280-315 nm) and uv-a (315-400 nm) radiation, seasonal variation in both environment and plant responses needs to be taken into account. this also has implications for studies concerning stratospheric ozone depletion and resulting increased uv-b radiation, as other environmental varia ...201020626643
wood anatomical analysis of alnus incana and betula pendula injured by a debris-flow event.vessel chronologies in ring-porous species have been successfully employed in the past to extract the climate signal from tree rings. environmental signals recorded in vessels of ring-porous species have also been used in previous studies to reconstruct discrete events of drought, flooding and insect defoliation. however, very little is known about the ability of diffuse-porous species to record environmental signals in their xylem cells. moreover, time series of wood anatomical features have on ...201020639516
ecology of coarse wood decomposition by the saprotrophic fungus fomes fomentarius.saprotrophic wood-inhabiting basidiomycetes are the most important decomposers of lignin and cellulose in dead wood and as such they attracted considerable attention. the aims of this work were to quantify the activity and spatial distribution of extracellular enzymes in coarse wood colonised by the white-rot basidiomycete fomes fomentarius and in adjacent fruitbodies of the fungus and to analyse the diversity of the fungal and bacterial community in a fungus-colonised wood and its potential eff ...201020668917
xanthine oxidase inhibitory properties of czech medicinal plants.to investigate in vitro xanthine oxidase inhibitory properties of plants traditionally used in czech republic and central-east europe region for gout, arthritis or rheumatism treatment.201020800669
leaf volatile emissions of betula pendula during autumn coloration and leaf fall.deciduous trees remobilize the nitrogen in leaves during the process of autumn coloration, thus providing a high quality food source for aphids preparing to lay over-wintering eggs. it has been suggested that aphids may use volatile organic compounds (vocs) to: (a) select leaves where nutrient remobilization has started and induced defenses are reduced; and (b) detect the time of leaf abscission. we analyzed vocs emitted by the foliage of betula pendula roth. during autumn coloration and from le ...201020838885
the effect of tree architecture on conduit diameter and frequency from small distal roots to branch tips in betula pendula, picea abies and pinus sylvestris.we studied the effect of tree architecture on xylem anatomy in three betula pendula roth., three picea abies (l.) h. karst. and three pinus sylvestris (l.) trees (mean age 35 years). first, the analysis of conduit anatomy in different tree parts showed that conduits tapered and their frequency increased from roots (≥ 2 mm) to stem, from stem to branches and further to leaf petioles in b. pendula. conduit anatomy in lateral and main roots, as well as lateral and main branches, significantly diffe ...201021030407
experimental evidence supporting the concept of light-mediated modulation of stem hydraulic conductance.it is a well-described phenomenon that plant leaves respond to changes in light intensity and duration by adjusting leaf hydraulic efficiency, and there is current consensus that up- or down-regulation of water channels (aquaporins) in the plasma membrane of the bundle sheath and mesophyll cells play a central role in the underlying mechanisms. recently, experimental evidence has been provided also for light-mediated changes of stem hydraulic conductance (k(stem)) in field-grown laurel plants. t ...201021071503
immunomodulatory effects of betulinic acid from the bark of white birch on mice.the objective of this study was to explore the immunomodulatory effects of betulinic acid (ba) extracted from the bark of white birch on mice. female mice were orally administered ba for 14 days in doses of 0, 0.25, 0.5, and 1 mg/kg body weight. we found that ba significantly enhanced the thymus and spleen indices, and stimulated lymphocyte proliferation induced by concanavalin a and lipopolysaccharide as shown by mtt assay. flow cytometry revealed that ba increased the percentage of cd4(+) cell ...201021113099
elevation of night-time temperature increases terpenoid emissions from betula pendula and populus tremula.volatile organic compounds (vocs) are expected to have an important role in plant adaptation to high temperatures. the impacts of increasing night-time temperature on daytime terpenoid emissions and related gene expression in silver birch (betula pendula) and european aspen (populus tremula) clones were studied. the plants were grown under five different night-time temperatures (6, 10, 14, 18, and 22 degrees c) while daytime temperature was kept at a constant 22 degrees c. voc emissions were col ...201020181662
flavonol quantification and stability of phenolics in fermented extracts from fresh betula pendula leaves.an hplc method, which allows reliable quantitation of flavonols and other phenolics in birch leaf extracts, was developed and validated. the method was applied to study the bioconversion of flavonols in fermented aqueous extracts. almost 100% of the flavonols were converted during the 12 months observation period. the generated phenolics as well as consecutive conversion products were identified by hplc-dad, lc-ms and gc-ms techniques.201020189738
the past, present and future tasks of hungarian dendrological research.hungarian dendrological research (research of living woody plants) has more than 200 years old history; the first general work by j+ínos kereszt+®ly grossinger was published in 1797. further basic works in our time yet are: forest botany by lajos fekete and s+índor m+íg+¦csy-dietz (1896); and the chorological work, distribution of trees and shrubs of sylvicultural importance in the region of hungarian state by lajos fekete and tibor blattny (1913). a few dendrologists and many botanists have hel ...201021565760
isolation, identification and sequence analysis of a thioredoxin h gene, a member of subgroup iii of h-type trxs from grape (vitis vinifera l. cv. askari).thioredoxins (trxs) are small ubiquitous proteins which play a regulatory role in a variety of cellular processes. in contrast to other organisms, plants have a great number of trx types, consisting of six well-defined groups: f, m, x, and y in chloroplasts, o in mitochondria, and h mainly in cytosol. a full-length cdna, designated vvcxxs2, encoding trx h polypeptide was isolated and cloned from grape (vitis vinifera l. cv. askari) berries organ by reverse transcription polymerase chain reaction ...201121732058
suppression of stat3 and hif-1 alpha mediates anti-angiogenic activity of betulinic acid in hypoxic pc-3 prostate cancer cells.signal transducer and activator of transcription 3 (stat3) is a transcription factor that regulates various cellular processes such as cell survival, angiogenesis and proliferation. in the present study, we examined that betulinic acid (ba), a triterpene from the bark of white birch, had the inhibitory effects on hypoxia-mediated activation of stat3 in androgen independent human prostate cancer pc-3 cells.201121731766
Liberomyces gen. nov. with two new species of endophytic coelomycetes from broad-leaved trees.During a study of endophytic and saprotrophic fungi in the sapwood and phloem of broad-leaved trees (Salix alba, Quercus robur, Ulmus laevis, Alnus glutinosa, Betula pendula), fungi belonging to an anamorphic coelomycetous genus not attributable to a described taxon were detected and isolated in pure culture. The new genus Liberomyces with two species, L. saliciphilus and L. macrosporus, is described. Both species have subglobose conidiomata containing holoblastic sympodial conidiogenous cells. ...201121937729
N(2) fixation and cycling in Alnus glutinosa, Betula pendula and Fagus sylvatica woodland exposed to free air CO(2) enrichment.We measured the effect of elevated atmospheric CO(2) on atmospheric nitrogen (N(2)) fixation in the tree species Alnus glutinosa growing in monoculture or in mixture with the non-N(2)-fixing tree species Betula pendula and Fagus sylvatica. We addressed the hypotheses that (1) N(2) fixation in A. glutinosa will increase in response to increased atmospheric CO(2) concentrations, when growing in monoculture, (2) the impact of elevated CO(2) on N(2) fixation in A. glutinosa is the same in mixture an ...201122179329
boron nutrition affects the carbon metabolism of silver birch seedlings.boron (b) is an essential micronutrient whose deficiency is common both in agriculture and in silviculture. boron deficiency impairs the growth of plants and affects many metabolic processes like carbohydrate metabolism. boron deficiency and also excess b may decrease the sink demand by decreasing the growth and sugar transport which may lead to the accumulation of carbohydrates and down-regulation of photosynthesis. in this study, we investigated the effects of b nutrition on the soluble and st ...201122084021
temporal variation in epidermal flavonoids due to altered solar uv radiation is moderated by the leaf position in betula pendula.the physiological mechanisms controlling plant responses to dynamic changes in ambient solar ultraviolet (uv) radiation are not fully understood: this information is important to further comprehend plant adaptation to their natural habitats. we used the fluorimeter dualex to estimate in vivo the epidermal flavonoid contents by measuring epidermal uv absorbance (a(375) ) in betula pendula roth (silver birch) leaves of different ages under altered uv. seedlings were grown in a greenhouse for 15 da ...201121883252
[karelian birch (betula pendula roth. var. carelica merkl.) as a model for studying genetic and epigenetic variation related to the formation of patterned wood].the results of long-term pioneering studies on in vitro micropropagation of karelian birch patterned forms and simultaneous cytological analysis of plants multiplied using different periods of in vitro culturing are published for the first time. the patterned wood character has been shown to be correlated with the degree of mixoploidy of its somatic tissue, which is higher in the plants obtained from callus cultures during the first years of culturing. subsequent intracellular selection leads to ...201121954616
inter- and intra-specific variation in stem phloem phenolics of paper birch (betula papyrifera) and european white birch (betula pendula).outbreaks of bronze birch borer (bbb) (agrilus anxius), a wood-boring beetle endemic to north america, have been associated with widespread mortality of birch (betula spp.). there is substantial inter- and intra-specific variation in birch resistance to bbb. species endemic to north america, such as paper birch (b. papyrifera), have coevolved with bbb and are more resistant than european and asian birch species, such as european white birch (b. pendula), which lack an evolutionary history with b ...201122012323
vertical profiles reveal impact of ozone and temperature on carbon assimilation of betula pendula and populus tremula.rising temperature and tropospheric ozone (o(3)) concentrations are likely to affect carbon assimilation processes and thus the carbon sink strength of trees. in this study, we investigated the joint action of elevated ozone and temperature on silver birch (betula pendula) and european aspen (populus tremula) saplings in field conditions by combining free-air ozone exposure (1.2 × ambient) and infrared heaters (ambient +1.2 °c). at leaf level measurements, elevated ozone decreased leaf ne ...201121856655
interspecific variation in resistance of asian, european, and north american birches (betula spp.) to bronze birch borer (coleoptera: buprestidae).bronze birch borer (agrilus anxius gory) is the key pest of birches (betula spp.) in north america, several of which have been recommended for ornamental landscapes based on anecdotal reports of borer resistance that had not been confirmed experimentally. in a 20-yr common garden experiment initiated in 1979 in ohio, north american birch species, including paper birch (betula papyrifera marshall), 'whitespire' gray birch (betula populifolia marshall), and river birch (betula nigra l.), were muc ...201122251643
chilling of dormant buds hyperinduces flowering locus t and recruits ga-inducible 1,3-beta-glucanases to reopen signal conduits and release dormancy in populus.in trees, production of intercellular signals and accessibility of signal conduits jointly govern dormancy cycling at the shoot apex. we identified 10 putative cell wall 1,3-ß-glucanase genes (glucan hydrolase family 17 [gh17]) in populus that could turn over 1,3-ß-glucan (callose) at pores and plasmodesmata (pd) and investigated their regulation in relation to ft and cenl1 expression. the 10 genes encode orthologs of arabidopsis thaliana bg_ppap, a pd-associated glycosylphosphatidylinositol (gp ...201121282527
quantification of lignin-carbohydrate linkages with high-resolution nmr spectroscopy.a quantitative approach to characterize lignin-carbohydrate complex (lcc) linkages using a combination of quantitative ¹³c nmr and hsqc 2d nmr techniques has been developed. crude milled wood lignin (mwlc), lcc extracted from mwlc with acetic acid (lcc-acoh) and cellulolytic enzyme lignin (cel) preparations were isolated from loblolly pine (pinus taeda) and white birch (betula pendula) woods and characterized using this methodology on a routine 300 mhz nmr spectrometer and on a 950 mhz spectrome ...201121298285
proteomic profiling of birch (betula verrucosa) pollen extracts from different origins.pollen of the european white birch is a major source of spring pollinosis in europe. pollen-allergy diagnosis and treatment by specific immunotherapy commonly rely on extracts of natural origin. to gain insight into the protein content and its variability, we evaluated the profile of allergenic and non-allergenic proteins in extracts of pollen from different origins by ms-based proteomics. aqueous extracts prepared from commercially available swedish birch pollen, pollen collected from austrian ...201121360672
how reliable is the double-ended pressure sleeve technique for assessing xylem vulnerability to cavitation in woody angiosperms?the reliability of a double-ended pressure sleeve technique was evaluated on three woody angiosperm species with contrasting maximum vessel lengths. vulnerability curves (vcs) were constructed by varying sample length and the size of the pressure sleeves. vcs were compared against curves obtained with reference techniques. for the two diffuse-porous species, betula pendula and prunus persica, vcs built with shoot segments shorter than maximum vessel length strongly overestimated species vulnerab ...201121401617
impact of light quality on leaf and shoot hydraulic properties: a case study in silver birch (betula pendula).responses of leaf and shoot hydraulic conductance to light quality were examined on shoots of silver birch (betula pendula), cut from lower ('shade position') and upper thirds of the crowns ('sun position') of trees growing in a natural temperate forest stand. hydraulic conductances of leaf blades (k(lb) ), petioles (k(p) ) and branches (i.e. leafless stem; k(b) ) were determined using a high pressure flow meter in steady state mode. the shoots were exposed to photosynthetic photon flux density ...201121414012
proteomic analysis of the major birch allergen bet v 1 predicts allergenicity for 15 birch species.pollen of the european and asian white birch (betula pendula and b. platyphylla) causes hay fever in humans. the allergenic potency of other birch species is largely unknown. to identify birch trees with a reduced allergenicity, we assessed the immunochemical characteristics of 15 species and two hybrids, representing four subgenera within the genus betula, while focusing on the major pollen allergen bet v 1. antigenic and allergenic profiles of pollen extracts from these species were evaluated ...201121459169
deer browsing and soil disturbance induce cascading effects on plant communities: a multilevel path analysis.understanding how large herbivores shape plant diversity patterns is an important challenge in community ecology, especially because many ungulate populations in the northern hemisphere have recently expanded. because species within plant communities can exhibit strong interactions (e.g., competition, facilitation), selective foraging by large herbivores is likely not only to affect the abundance of palatable species, but also to induce cascading effects across entire plant communities. to inves ...201121563575
an aqueous birch leaf extract of betula pendula inhibits the growth and cell division of inflammatory lymphocytes.ethnopharmacological relevance: leaf extracts of betula pendula have been traditionally used for the treatment of patients with rheumatoid arthritis (ra) or osteoarthritis. aim of the study: we investigated the anti-proliferative capacity of an aqueous leaf extract of betula pendula (bpe) on human primary lymphocytes in vitro, because activated lymphocytes play a major role in the initiation and maintenance of ra. materials and methods: lymphocyte proliferation and cell division was measured by ...201121619918
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