does lignin modification affect feeding preference or growth performance of insect herbivores in transgenic silver birch (betula pendula roth)?transgenic silver birch (betula pendula roth) lines were produced in order to modify lignin biosynthesis. these lines carry comt (caffeate/5-hydroxyferulate o-methyltransferase) gene from populus tremuloides driven by constitutive promoter 35s camv (cauliflower mosaic virus) or ubb1 (ubiquitin promoter from sunflower). the decreased syringyl/guaiacyl (s/g) ratio was found in stem and leaf lignin of 35s camv-ptcomt transgenic silver birch lines when compared to non-transformed control or ubb1-ptc ...200515971066
expression of senescence-associated genes in the leaves of silver birch (betula pendula).development was monitored throughout the entire life span of silver birch (betula pendula roth.) leaves. the focus was on senescence-related changes in photosynthesis and gene expression. the youngest fully developed leaves were compared with older senescing leaves in two silver birch lines: the wild-type line r and a late-senescing line r3.1. line r3.1 was found among transgenic lines produced with a plasmid containing sense-rbcs and nptii under the control of the 35s camv promoter. compared wi ...200515996959
spatial patterns of gene expression in the extramatrical mycelium and mycorrhizal root tips formed by the ectomycorrhizal fungus paxillus involutus in association with birch (betula pendula) seedlings in soil microcosms.functional compartmentation of the extramatrical mycelium of ectomycorrhizal (ecm) fungi is considered important for the operation of ecm associations, although the molecular basis is poorly characterized. global gene expression profiles of mycelium colonizing an ammonium sulphate ((nh4)2so4) nutrient patch, rhizomorphs and ecm root tips of the betula pendula-paxillus involutus association were compared by cdna microarray analysis. the expression profiles of rhizomorphs and nutrient patch myceli ...200515998408
global patterns of gene regulation associated with the development of ectomycorrhiza between birch (betula pendula roth.) and paxillus involutus (batsch) fr.the formation of ectomycorrhizal (ecm) root tissue is characterized by distinct morphological and developmental stages, such as preinfection and adhesion, mantle, and hartig net formation. the global pattern of gene expression during these stages in the birch (betula pendula)-paxillus involutus ecm association was analyzed using cdna microarrays. in comparison with nonsymbiotic conditions, 251 fungal (from a total of 1,075) and 138 plant (1,074 in total) genes were found to be differentially reg ...200516042012
linkage map of birch, betula pendula roth, based on microsatellites and amplified fragment length polymorphisms.the first genetic linkage map for silver birch, betula pendula roth, was constructed by using a pseudo-testcross mapping strategy and integration of linkage data from 3 unrelated 2-generation pedigrees. the map is based on the genetic inheritance and segregation of 82 amplified fragment length polyhmorphisms and 19 microsatellite markers, and was constructed by simultaneously comparing the performance of cri-map and outmap packages. the analysis revealed 16 linkage groups, and the total map cove ...200516094429
variation in birch (betula pendula) shoot secondary chemistry due to genotype, environment, and ontogeny.plant secondary chemistry is determined by both genetic and environmental factors, and large intraspecific variation in secondary chemistry has frequently been reported. the heritability of specific tree secondary metabolites is, however, mostly unknown. we tested the effect of plant genotype, environment, and ontogeny on the variation in shoot secondary chemistry of juvenile and mature european white birches (betula pendula). phenolic compounds and triterpenoids were analyzed in 30 naturally re ...200516124246
differential responses of silver birch (betula pendula) ecotypes to short-day photoperiod and low temperature.we investigated interrelations of dormancy and freezing tolerance and the role of endogenous abscisic acid (aba) in the development of silver birch (betula pendula roth) ecotypes in controlled environments. short-day treatment induced growth cessation, bud set and dormancy development, as well as initiation of cold acclimation and an increase in freezing tolerance. subsequent low temperature and short days (12-h photoperiod) resulted in a significant increase in freezing tolerance, whereas bud d ...200516137942
vitrification, a complementary cryopreservation method for betula pendula roth.cryopreservation--the storage of plant germplasm in liquid nitrogen--provides a modern tool for the conservation of forest genetic resources. it is especially applicable for species in which their micropropagation can be initiated from mature tree buds, e.g., silver birch (betula pendula roth), thus enabling the conservation of specific genotypes: endangered elite trees and trees expressing rare, valuable or interesting characteristics. the aim of the present study was to develop a vitrification ...200516139833
delayed induced responses of birch glandular trichomes and leaf surface lipophilic compounds to mechanical defoliation and simulated winter browsing.changes in morphology and chemistry of leaf surface in response to herbivore damage may increase plant resistance to subsequent herbivore attack; however, there is lack of studies on induced responses of glandular trichomes and their exudates in woody plants and on effects of these changes on herbivores. we studied delayed induced responses in leaf surface traits of five clones of silver birch (betula pendula roth) subjected to various types of mechanical defoliation and simulated winter browsin ...200516187111
ontogeny and environment as determinants of the secondary chemistry of three species of white birch.this study investigates variation in the secondary chemistry of the bark of three closely related, winter-dormant species of white birch (betula resinifera, b. pendula, and b. platyphylla) at different ontogenetic stages by using different plant parts (top and base). the experimental birches were grown for 4 years in two growing conditions (pot and field) at different nutrient levels. there was considerable species-specific quantitative and qualitative variation in the secondary chemicals in bar ...200516195842
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
[137cs and 90sr accumulation in birch wood (betula pendula roth.) growing in regions with different soil conditions].the studies of 137cs and 90sr accumulation characteristics by birch wood (betula pendula roth.) growing in different edaphic conditions. were conducted was stated that the increase in soil fertility from trophotops a to d results in 5-fold 137cs transfer factor decrease and 2-fold decrease of 90sr. soil humidity increase for each grade of trophic net results happens the increase of 137cs transfer factors to wood and decrease for 90sr. total activity of 37cs and 90sr in birch wood plantation depe ...200516209198
deciphering the 820 nm signal: redox state of donor side and quantum yield of photosystem i in recording leaf transmittance at 820 nm and quantifying the photon flux density of far red light (frl) absorbed by long-wavelength chlorophylls of photosystem i (ps i), the oxidation kinetics of electron carriers on the ps i donor side was mathematically analyzed in sunflower (helianthus annuus l.), tobacco (nicotiana tabacum l.) and birch (betula pendula roth.) leaves. ps i donor side carriers were first oxidized under frl, electrons were then allowed to accumulate on the ps i donor side duri ...200316245060
the chemistry of soils, rocks and plant bioindicators in three ecosystems of the holy cross mountains, june of 2000, biogeochemical study was carried out in three ecosystems of the holy cross mountains (south-central poland). this paper presents element concentrations and stable sulfur (and in one site lead) isotope ratios in rocks, detailed soil profiles, and plant bioindicators including epiphytic lichen hypogymnia physodes (l.) nyl., mosses (pleurozium schreberi (brid.) mitt., hypnum cupressiforme hedw. s. str., hylocomium splendens (hedw.) b.s.g.), scots pine (pinus sylvestris l.), common ...200516308778
degradability of dissolved soil organic carbon and nitrogen in relation to tree species.the degradability and chemical characteristics of water-extractable dissolved organic carbon (doc) and nitrogen (don) from the humus layer of silver birch (betula pendula roth), norway spruce (picea abies (l.) karst.) and scots pine (pinus sylvestris l.) stands were compared in short-term incubation of soil solutions. for all extracts the degradation of doc and don was low (12-17% loss) and increased in the order: birch, spruce and pine. in the humus layer under pine a relatively larger pool of ...200516329927
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
monolignol oxidation by xylem peroxidase isoforms of norway spruce (picea abies) and silver birch (betula pendula).we partially purified peroxidase isoform fractions from xylem extracts of a gymnosperm, norway spruce (picea abies (l.) karst.), and an angiosperm, silver birch (betula pendula roth.), to determine the participation of xylem-localized peroxidases in polymerization of different types of lignin in vivo. several peroxidase fractions varying in isoelectric point values from acidic to basic were tested for their ability to catalyze the oxidation of the monolignols coniferyl alcohol, sinapyl alcohol a ...200616452074
contribution of omega-3 fatty acid desaturase and 3-ketoacyl-acp synthase ii (kasii) genes in the modulation of glycerolipid fatty acid composition during cold acclimation in birch leaves.temperate and boreal tree species respond to low positive temperatures (lt) or a shortening of the photoperiod (sd) by inducing cold acclimation. one of the metabolic consequences of cold acclimation is an increase in fatty acid (fa) desaturation in membrane lipids, which allows functional membrane fluidity to be maintained at lt. the molecular mechanisms of fa desaturation were investigated in leaves of birch seedlings (betula pendula) during cold acclimation. four genes involved in fa biosynth ...200616473891
black teeth: beauty or caries prevention? practice and beliefs of the kammu be beautiful and caries-free, kammu women in laos and vietnam habitually paint their teeth black. although this practice existed for many generations, it is now known only among the elderly.200616515671
[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
effects of metal-contaminated soil on the performance of young trees growing in model ecosystems under field conditions.young populus tremula, salix viminalis, betula pendula and picea abies trees were grown together in large open-top chambers. the treatments were: without or with (cu/zn/cd/pb=640/3000/10/90 mg kg-1) metal contamination in the topsoil, irrigation ph 3.5 or 5.5, and acidic or calcareous subsoil. growth, metal allocation to foliage and wood, as well as leaf gas exchange were measured. biomass was reduced in p. tremula and b. pendula by the metal-contaminated topsoil relative to uncontaminated topso ...200616540218
transitions in the functioning of the shoot apical meristem in birch (betula pendula) involve 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
critical night length for bud set and its variation in two photoperiodic ecotypes of betula pendula.we studied the variation in critical night length for bud set in two photoperiodic ecotypes (two latitudinally distant stands) of silver birch (betula pendula roth) in three phytotron experiments. seeds from 21 open-pollinated mother trees in a southern (tuusula, 60 degrees n) and a northern (kittilä, 67 degrees n) finnish stand were germinated and grown for 4 weeks in a 24-h photoperiod in a greenhouse and then moved to different night length treatments at 18 degrees c for 4 to 6 weeks. night l ...200616651250
metabolic response of river birch and european birch and european birch roots to hypoxia.flood tolerance of woody plants has been attributed to internal oxygen diffusion from shoot to root, metabolic adaptation within the root, or both. the purpose of this study was to compare several biochemical and physiological responses of birch roots to hypoxia in order to determine the nature of root metabolic adaptation to low oxygen tension. one-year-old seedlings of flood-tolerant river birch (betula nigra l.) and flood-intolerant european birch (betula pendula roth) were transferred to sol ...198416663817
induction of nitrate assimilatory enzymes in the tree betula pendula.the coordinate appearance of the bispecific nad(p)h-nitrate reductase (nr; ec and nitrite reductase (nir; ec was investigated in leaves and roots from european white birch seedlings (betula pendula roth). induction by nitrate and light of both enzymes was analyzed by in vitro assays and by measuring nr- and nir-encoding mrna pools with homologous cdnas as probes. when birch seedlings were grown on a medium containing ammonium as the sole nitrogen source, low constitutive expres ...199216669009
relationships between stand composition and ectomycorrhizal community structure in boreal mixed-wood forests.we investigated the community structure of ectomycorrhizal fungi under varying overstory tree compositions in the southern mixed-wood boreal forest of quebec. sampling took place at two locations of differing postfire ages and nine 100-m2 plots were sampled per location. the dominant overstory tree species in the plots were trembling aspen (populus tremuloides michx.), white birch (betula papyrifera marsh.) or white spruce [picea glauca (moench) voss], and balsam fir [abies balsamea (l.) mill.]. ...200616699911
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
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
[the cytogenetic monitoring of the environmental conditions on the territories exposed by the radioactive contamination as a result of chernobyl nuclear power station accident (colony urazovo belgorod region as an example)].cytogenetic characteristics of the seed progeny of birch (betula pendula roth), growing in colony urazovo belgorod region exposed by the impact of chernobyl precipitation in 1986, were determinated. the changing of cytogenetic characteristics in comparison with the control (mitotic index and level of mitosis pathologies grown, their spectrum widens part of persistent nucleolies at the stages of metaphase, anaphase, telophase of mitosis enlarges, square of surface of single nucleolies decreases, ...200616756118
photosystem ii cycle and alternative electron flow in leaves.sunflower (helianthus annuus l.) and tobacco (nicotiana tabacum l.) were grown in the laboratory and leaves were taken from field-grown birch trees (betula pendula roth). chlorophyll fluorescence, co2 uptake and o2 evolution were measured and electron transport rates were calculated, j(c) from the co2 uptake rate considering ribulose-1,5-bisphosphate (rubp) carboxylation and oxygenation, j(o) from the o2 evolution rate, and j(f) from chl fluorescence parameters. mesophyll diffusion resistance, r ...200616774929
assessment of metal availability to vegetation (betula pendula) in pb-zn ore concentrate residues with different 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
twilight far-red treatment advances leaf bud burst of silver birch (betula pendula).bud development of boreal trees in spring, once initiated, is driven by ambient air temperature, but the mechanism triggering bud development remains unclear. we determined if some aspect of the diurnal or seasonal light regime influences initiation of bud burst once the chilling requirement is met. we grew 3-year-old birch plantlets cloned from a mature tree of boreal origin in light conditions realistically simulating the lengthening days of spring at 60 degrees n. to emulate the reduction in ...200616815827
seven different genes encode a diverse mixture of isoforms of bet v 1, the major birch pollen allergen.pollen of the european white birch (betula pendula, syn. b. verrucosa) is an important cause of hay fever. the main allergen is bet v 1, member of the pathogenesis-related class 10 (pr-10) multigene family. to establish the number of pr-10/bet v 1 genes and the isoform diversity within a single tree, pcr amplification, cloning and sequencing of pr-10 genes was performed on two diploid b. pendula cultivars and one interspecific tetraploid betula hybrid. sequences were attributed to putative genes ...200616820045
root penetration of sealing layers made of fly ash and sewage ash and sewage sludge are suggested materials for constructing sealing layers covering mine tailings impoundments. little is known, however, of their effect on vegetation or resistance to root penetration. we investigate: (i) the ability of different plant species to grow in sealing layers comprising fly ash and sewage sludge, (ii) the impact on plant growth of freshly hardened fly ash compared to aged and leached ash, and (iii) the plant stress response to fly ashes of different properties. ...200616825445
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
effects of carbon dioxide concentration and nutrition on photosynthetic functions of white birch investigate the interactive effects of atmospheric carbon dioxide concentration ([co(2)]) and nutrition on photosynthesis and its acclimation to elevated [co(2)], a two-way factorial experiment was carried out with two nutritional regimes (high- and low-nitrogen (n), phosphorus (p) and potassium (k)) and two co(2) concentrations (360 and 720 ppm) with white birch seedlings (betula papyrifera marsh.) grown for four months in environment-controlled greenhouses. elevated [co(2)] enhanced maximal ...200616877330
[long-term effects of different planting proportion on forest landscape in great hing' anling mountains after the catastrophic fire in 1987].with landis model, this paper simulated the long-term dynamics of 100% larch (p1) 70% larch and 30% mongolian scotch pine (p2), 50% larch and 50% mongolian scotch pine (p3), 30% larch and 70% mongolian scotch pine (p4), and 100% mongolian scotch pine (p5) in the tuqiang forest bureau at the northern slope of great hing' anling mountains after the catastrophic fire in 1987, taking the forest under natural regeneration as the reference. the results showed that at the early, medium, and late stages ...200616883815
aboveground and belowground responses to quality and heterogeneity of organic inputs to the boreal forest.leaf litter and other organic resources returned to the soil are important regulators of ecological processes in forest ecosystems, and their ecological impacts may be strongly influenced both by their quality and by interactions between coexisting resource types. to date, most studies on effects of resource identity and mixing have only involved leaf litter, despite the fact that other resource types constitute a major input to the soil. we investigated how quality and heterogeneity of organic ...200616896771
betulinic acid decreases expression of bcl-2 and cyclin d1, inhibits proliferation, migration and induces apoptosis in cancer cells.betulinic acid (ba) is a pentacyclic triterpene found in many plant species, among others in the bark of white birch betula alba. ba was reported to display a wide range of biological effects, including antiviral, antiparasitic, antibacterial and anti-inflammatory activities, and in particular to inhibit growth of cancer cells. the aim of the study was further in vitro characterization of ba anticancer activity. in this study, we demonstrated a remarkable antiproliferative effect of ba in all te ...200616964520
tree species effects on decomposition and forest floor dynamics in a common garden.we studied the effects of tree species on leaf litter decomposition and forest floor dynamics in a common garden experiment of 14 tree species (abies alba, acer platanoides, acer pseudoplatanus, betula pendula, carpinus betulus, fagus sylvatica, larix decidua, picea abies, pinus nigra, pinus sylvestris, pseudotsuga menziesii, quercus robur, quercus rubra, and tilia cordata) in southwestern poland. we used three simultaneous litter bag experiments to tease apart species effects on decomposition v ...200616995629
intraspecific competition, growth, chemistry, and susceptibility to voles in seedlings of betula pendula.we studied the effects of the intensity of intraspecific competition, as indicated by seedling density, and competitive success within populations, as indicated by seedling size, on the secondary chemistry of the stems of silver birch seedlings and their palatability to field voles. we found that the size of seedlings and their total phenolic concentrations were inversely related to stand density. voles, however, did not discriminate between seedlings grown at the densities studied. variation in ...200617001532
diversity of the small subunit ribosomal rna gene of the arbuscular mycorrhizal fungi colonizing clintonia borealis from a mixed-wood boreal forest.arbuscular mycorrhizal fungi (amf) communities in clintonia borealis roots from a boreal mixed forests in northwestern québec were investigated. roots were sampled from 100 m2 plots whose overstory was dominated by either trembling aspen (populus tremuloides michx.), white birch (betula papyrifera marsh.), or mixed white spruce (picea glauca (moench) voss) and balsam fir (abies balsamea (l.) mill.). part of the 18s ribosomal gene of the amf was amplified and the resulting pcr products were clone ...200617064264
stem co2 release under illumination: corticular photosynthesis, photorespiration or inhibition of mitochondrial respiration?in illuminated stems and branches, co2 release is often reduced. many light-triggered processes are thought to contribute to this reduction, namely photorespiration, corticular photosynthesis or even an inhibition of mitochondrial respiration. in this study, we investigated these processes with the objective to discriminate their influence to the overall reduction of branch co2 release in the light. co2 gas-exchange measurements of young birch (betula pendula roth.) branches (< 1.5 cm) performed ...200617080940
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
irradiance-induced plasticity in the hydraulic properties of saplings of different temperate broad-leaved forest tree species.we assessed the irradiance-related plasticity of hydraulic architecture in saplings of betula pendula roth., a pioneer species; acer pseudoplatanus l., fraxinus excelsior l. and quercus robur l., which are post-pioneer light-requiring species; and quercus petraea matt. liebl. and fagus sylvatica l. plants were grown in pots in 36%, 16% and 4% of full sunlight. hydraulic conductance was measured with a high-pressure flow-meter in entire, in situ root systems and in excised shoots. leaf-specific w ...200617169890
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
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
new dammaranes, esterified with malonic acid, from leaves of betula pendula.three known and five new dammarane triterpenes, esterified with malonic acid at c-3 with hemolytic activity were identified from the ethanol-water extract of leaves of betula pendula roth: 12-o-acetyl-3alpha,12beta,20(s),24(r)-tetrahydroxydammar-25-en-3-yl hydrogen propanedioate, 12-o-acetyl-3alpha,12beta20(s),24(s)-tetrahydroxydammar-25-en-3-yl hydrogen propanedionate, 12-o-acetyl-3alpha,12beta,17alpha,20(s),24(r)-pentahydroxydammar-25-en-3-yl hydrogen propanedioate, [12beta-acetoxy-4,4,8,10,14 ...199717252393
root penetration through sealing layers at mine deposit prevent acid mine drainage arising from oxygen and water penetration of sulphide-rich mine tailings, the tailings are covered with layers of dry sealing material. plant roots have a great ability to penetrate dense materials, and if the roots are able to penetrate the sealing layer of a tailings deposit, its oxygen-shielding properties could be reduced. the objective of this study was to evaluate whether plant roots are able to penetrate sealing layers covering mine tailings deposits. root pe ...200617253002
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
relationship between photosynthesis and leaf nitrogen concentration in ambient and elevated [co2] in white birch 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
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
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 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
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
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
expression of xyloglucan endotransglycosylases of gerbera hybrida and betula pendula in pichia pastoris.the plant enzyme xyloglucan endotransglycosylase (xet; ec, 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
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
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
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
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
[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
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
[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
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
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
screening analyses of pinosylvin stilbenes, resin acids and lignans in norwegian conifers.the content and distribution of stilbenes and resin acids in scots pine (pinus sylvestris) and spruce (picea abies), sampled in central norway, have been examined. the contents of pinosylvin stilbenes in pine heartwood/living knots were 0.2-2/2-8 %(w/w). no stilbenes could be detected in spruce (picea abies). the resin acid contents of pine sapwood/heartwood and knots were 1-4 and 5-10 % (w/w), respectively. minor amounts of resin acids (<0.2/<0.04 %w/w) were identified in spruce wood/knots. the ...200617962750
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
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
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
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
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
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
classification of plant somatic embryos by computer vision.this article deals with the automation of the process of somatic embryogenesis for the propagation of plants. an important problem is the monitoring of the embryo production process in order to decide the time to start harvesting embryos for further processing. the classification algorithm development for somatic embryos of birch (betula pendula roth) showed that automated recognition of embryos at different developmental stages is possible. no globular stage embryos were classified to be heart ...199318601243
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
effect of tree species and mycorrhizal colonization on the archaeal population of boreal forest 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
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
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