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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
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
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
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
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
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
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
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
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
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
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
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
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
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
interactions of ectomycorrhizas and above-ground insect herbivores on silver birch. 200919794863
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
[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
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
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
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
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
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
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
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
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
the allergen profile of beech and oak pollen.beech and oak pollen are potential allergen sources with a world-wide distribution.200818754759
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
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
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
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
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
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
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
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
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
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
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
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
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
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
temperature sum accumulation effects on within-population variation and long-term trends in date of bud burst of european white birch (betula pendula).within-population variation in phenology of boreal trees indicates their adaptability to climatic variations. although interannual variations in date of bud burst have been widely discussed, little is known about within-population variation, the key determinants for this variation and the effects of this variation on estimates of trends in bud burst date. over a period of nine years, we monitored timing of bud burst daily in 30 mature white birch (betula pendula roth) trees in a naturally regene ...200717403655
the seasonal activity and the effect of mechanical bending and wounding on the ptcomt promoter in betula pendula roth.in this study, 900-bp (signed as p including nucleotides -1 to -886) and partly deleted (signed as dp including nucleotides -1 to -414) comt (caffeate/5-hydroxyferulate o-methyltransferase) promoters from populus tremuloides michx. were fused to the gus reporter gene, and the tissue-specific expression patterns of the promoters were determined in betula pendula roth along the growing season, and as a response to mechanical bending and wounding. the main activity of the ptcomtp- and ptcomtdp-prom ...200717431633
expression of xyloglucan endotransglycosylases of gerbera hybrida and betula pendula in pichia pastoris.the plant enzyme xyloglucan endotransglycosylase (xet; ec 2.4.1.207, xyloglucan:xyloglucosyl transferase) participates in selective modification of plant cell walls during cell growth. xets are potential catalysts in various applications. here, sequences encoding two xets from gerbera hybrida and betula pendula are reported. the encoded proteins, which are 51% identical at the amino acid level, were expressed in the yeast pichia pastoris in secreted form with the aid of mating factor alpha signa ...200717462775
effects of ozone impact on the gas exchange and chlorophyll fluorescence of juvenile birch stems (betula pendula roth.).effects of ozone impact on gas exchange and chlorophyll fluorescence of juvenile birch (betula pendula) stems and leaves were investigated. significant differences in the response of leaves and stems to ozone were found. in leaves, o3 exposure led to a significant decline in photosynthetic rates, whereas stems revealed an increased dark respiration and a concomitant increase in corticular photosynthesis. in contrast to birch leaves, corticular photosynthesis appeared to support the carbon balanc ...200717374426
relationship between photosynthesis and leaf nitrogen concentration in ambient and elevated [co2] in white birch seedlings.to study the effects of elevated co2 concentration ([co2]) on relationships between nitrogen (n) nutrition and foliar gas exchange parameters, white birch (betula papyrifera marsh.) seedlings were exposed to one of five n-supply regimes (10, 80, 150, 220, 290 mg n l(-1)) in either ambient [co2] (360 micromol mol(-1)) or elevated [co2] (720 micromol mol(-1)) in environment-controlled greenhouses. foliar gas exchange and chlorophyll fluorescence were measured after 60 and 80 days of treatment. pho ...200717331907
leaf litter decomposition differs among genotypes in a local betula pendula population.ecosystem processes, such as plant litter decomposition, are known to be partly genetically determined, but the magnitude of genetic variation within local populations is still poorly known. we used micropropagated field-grown saplings of 19 betula pendula genotypes, representing genetic variation in a natural birch population, to examine (1) whether genotype can explain variation in leaf litter decomposition within a local plant population, and (2) whether genotypic variation in litter decompos ...200717361453
pollen proteolytic enzymes degrade tight junctions.asthma and allergic rhinitis are significant, increasing causes of morbidity worldwide. pollen, a major cause of seasonal rhinitis/conjunctivitis, carries proteolytic enzymes on its surface. we showed previously that peptidase allergens from house dust mites compromise epithelial barrier function by degrading the extracellular domains of the tight junction proteins, occludin and claudin, thus facilitating allergen delivery across epithelial layers. in this study, we aimed to determine whether pe ...200717986111
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
high accumulation of soluble sugars in deep supercooling japanese white birch xylem parenchyma cells.seasonal changes in the accumulation of soluble sugars in extracellular freezing cortical parenchyma cells and deep supercooling xylem parenchyma cells in japanese white birch (betula platyphylla var. japonica) were compared to identify the effects of soluble sugars on the mechanism of deep supercooling, which keeps the liquid state of water in cells under extremely low temperatures for long periods. soluble sugars in both tissues were analyzed by high-performance liquid chromatography (hplc), a ...200717447912
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
isolation of genes up-regulated by copper in a copper-tolerant birch (betula pendula) clone.suppression subtractive hybridization (ssh) was used to isolate genes differentially expressed following exposure to copper (cu) in a naturally selected cu-tolerant birch (betula pendula roth.) clone originating from a disused lead/zinc smelter. of the 352 cdna fragments initially isolated, 108 were up-regulated by cu, of which 55 showed over twofold induction by macroarray analysis. searches against protein databases (blastx) and sequence analysis provided the tentative identity of 21 genes. th ...200717545124
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
interaction of drought and elevated co2 concentration on photosynthetic down-regulation and susceptibility to photoinhibition in japanese white birch seedlings grown with limited n availability.the interaction of drought and elevated carbon dioxide concentration ([co(2)]) on carboxylation capacity of rubisco (v(cmax)) and susceptibility to photoinhibition may be an important determinant of plant responses to seasonal fluctuations in precipitation in an anticipated elevated [co(2)] environment. japanese white birch (betula platyphylla var. japonica) leaves that developed wholly during a period of drought showed an increase in leaf nitrogen and a decrease in leaf carbohydrates that could ...200717267363
[genetic linkage map of betula pendula roth and betula platyphylla suk based on random amplified polymorphisms dna markers].based on the genetic inheritance and segregation of random amplified polymorphism dna (rapds) markers, the first mid-density linkage map for silver birch was constructed by using a pseudo-testcross mapping strategy. a segregating population including 80 progenies from the cross between betula pendula roth and b. platyphylla suk was obtained. a set of 1,200 random oligonucleotide primers were screened, and 208 primers were selected to generate rapd markers within a sample of 80 f1 progenies. a to ...200717646154
fragmented environment affects birch leaf endophytes.the effect of environmental fragmentation on the species distribution and frequency of horizontally transmitted endophytic fungi in betula pubescens and betula pendula leaves was studied in an archipelago in southwestern finland. the study system consisted of 14 islands, ranging in size and distance to the mainland, and five mainland sites. endophytic fungi were grown out from surface-sterilized leaves. the frequency of endophytic fungi mainly depended on the size of the island, explaining 32-35 ...200717635229
fine root morphological adaptations in scots pine, norway spruce and silver birch along a latitudinal gradient in boreal forests.variability in short root morphology of the three main tree species of europe's boreal forest (norway spruce (picea abies l. karst.), scots pine (pinus sylvestris l.) and silver birch (betula pendula roth)) was investigated in four stands along a latitudinal gradient from northern finland to southern estonia. silver birch and scots pine were present in three stands and norway spruce was present in all stands. for three fertile norway spruce stands, fine root biomass and number of root tips per s ...200717669752
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
a noninvasive optical system for the measurement of xylem and phloem sap flow in woody plants of small stem size.over the past 70 years, heat has been widely used as a tracer for estimating the flow of water in woody and herbaceous plants. however, most commercially available techniques for monitoring whole plant water use are invasive and the measurements are potentially flawed because of wounding of the xylem tissue. the study of photosynthate transport in the phloem remains in its infancy, and little information about phloem transport rates is available owing to the fragility of the vascular tissue. the ...200717241960
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
immunomodulatory effects of aqueous birch pollen extracts and phytoprostanes on primary immune responses in vivo.we recently demonstrated that pollen not only function as allergen carriers but also as rich sources of bioactive lipids, such as phytoprostanes, that modulate human dendritic cell (dc) function in a way that results in an enhanced t(h)2 polarization in vitro.200717451798
comparison of 226ra nuclide from soil by three woody species betula pendula, sambucus nigra and alnus glutinosa during the vegetation period.the uptake of 226ra from the contaminated soil was compared in three woody species: alder (alnus glutinosa), birch (betula pendula) and elder (sambucus nigra). the 226ra activities increased during the vegetation periods (in 2003, 2004 and 2005) both in the leaves and flowers+seeds. the highest accumulation was found in birch, reaching 0.41 bq/g dw in the leaves (at the end of the vegetation period in 2003). the lowest 226ra accumulation was determined in alder. the extent of 226ra accumulation ...200717467859
dynamics of nitrogen and dissolved organic carbon at the hubbard brook experimental forest.the factors controlling spatial and temporal patterns in soil solution and streamwater chemistry are highly uncertain in northern hardwood forest ecosystems in the northeastern united states, where concentrations of reactive nitrogen (nr) in streams have surprisingly declined over recent decades in the face of persistent high rates of atmospheric nr deposition and aging forests. reactive nitrogen includes inorganic species (e.g., ammonium [nh4+], nitrate [no3-]) and some organic forms (e.g., ami ...200717536402
intermediates in the oxidative pathway from torulene to torularhodin in the red yeasts cystofilobasidium infirmominiatum and c. capitatum (heterobasidiomycetes, fungi).two red cystofilobasidium spp. isolated from spring sap-flows of betula pendula were analysed for their carotenoid content. in cystofilobasidium infirmominiatum, three unusual pigments were detected and identified by structure elucidation as oxidised torulene derivatives. these included 16'-hydroxytorulene and torularhodinaldehyde, two carotenoids known so far only from chemical synthesis or as postulated biosynthetic intermediates en route to torularhodin. unprecedented formation of beta-apo-2' ...200717597170
[allergy to macadamia nut].the patient was a 23-year-old female with a history of atopic dermatitis, allergic rhinitis, and allergic conjunctivitis. in her fourth year of primary school, she ate macadamia nuts and developed oral discomfort and generalized uticaria. in her second year of junior high school, she ate macadamia nuts and developed oral and pharyngeal discomfort, followed by generalized uticaria and dyspnea. at the age of 20 years, she also developed oral discomfort after eating vegetables in a chinese dish con ...200717671413
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
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
budburst phenology of white birch in industrially polluted areas.effects of environmental contamination on plant seasonal development have only rarely been properly documented. monitoring of leaf growth in mountain birch, betula pubescens subsp. czerepanovii, around a nickel-copper smelter at monchegorsk hinted advanced budburst phenology in most polluted sites. however, under laboratory conditions budburst of birch twigs cut in late winter from trees naturally growing around three point polluters (nickel-copper smelter at monchegorsk, aluminium factory at ka ...200717175079
spacing of silver birch seedlings grown in containers of equal size affects their morphology and its variability.silver birch (betula pendula roth) seedlings were grown individually in containers arranged in rows radiating from a central point (nelder plot) at densities spanning the range from 207 to 891 plants m(-2). height of one set of seedlings was measured at weekly intervals and additional seedlings were harvested each week for dry mass and leaf area measurements. height and shoot:root dry mass ratio increased with plant density. seedling-to-seedling variability in dry mass, but not height, increased ...200616740498
ozone impairs autumnal resorption of nitrogen from birch (betula pendula) leaves, causing an increase in whole-tree nitrogen loss through litter fall.saplings of one half-sib family of birch, betula pendula roth, were exposed to three ozone concentrations (non-filtered air (nf); non-filtered air + 10-20 nmol o(3) mol(-1) (nf+); non-filtered air + 40-60 nmol o(3) mol(-1) (nf++)) in open-top chambers during two growing seasons from 1997 to 1998. shed leaves were collected regularly during both growing seasons and, in 1998, the dry mass (dm) and nitrogen (n) concentrations ([n]) of the shed leaves were measured to quantify the total amount of n ...200616203721
a new mads-box gene (ibmads10) from sweet potato (ipomoea batatas (l.) lam) is involved in the accumulation of anthocyanin.a new mads-box gene designated as ibmads10 was cloned and its expression was characterized from sweet potato (ipomoea batatas (l.) lam.) cv. beniazuma. the deduced amino acid sequence of the gene indicated high homology with members of the mads-box family of transcription factors. ibmads10 shares high amino acid sequence similarity with the defh28 of antirrhinum majus (64%) and with bpmads4 of betula pendula (61%) of the squa subfamily. southern blot analysis revealed that the ibmads10 is presen ...200616333667
[the use of nucleolar morphological characteristics of birch seedlings for the assessment of environmental pollution].micronucleus frequency in buccal mucosa from the oral cavity of children as well as nucleolar structural characteristics (surface area of single nucleoli as well as their number and type) in the root meristem of seed progeny of birch (betula pendula roth) were studied in some districts of voronezh city and voronezh region (novovoronezh town, zemlyansk village). similar trends of changes in cytogenetic parameters have been revealed for both subjects. regression analysis allowed us to generate an ...200616521544
transitions in the functioning of the shoot apical meristem in birch (betula pendula) involve ethylene.in many trees, a short photoperiod (sd) triggers substantial physiological adjustments necessary for over-wintering. we have used transgenic ethylene-insensitive birches (betula pendula), which express the arabidopsis ethylene receptor gene etr1 carrying the dominant mutation etr1-1, to investigate the role of ethylene in sd-induced responses in the shoot apical meristem (sam). under sd, the ethylene-insensitive trees ceased elongation growth comparably to the wild-type. in contrast, the formati ...200616640599
hplc analysis of leaf surface flavonoids for the preliminary classification of birch species.flavonoid aglycones found on the surfaces of birch (betula spp.) leaves may constitute up to 10% of the dry weight of the leaf. a facile extraction and hplc procedure has been developed that can be used for the preliminary classification of birch species according to the patterns of their leaf surface flavonoids. the procedure involves no complex sample preparation steps, and is able to provide hplc chromatograms from fresh leaves in less than 30 min. if necessary, leaves do not even need to be ...200616749428
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