Publications
| Title | Abstract | Year(sorted descending) Filter | PMID Filter |
|---|
| 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 ... | 2006 | 16896771 |
| 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 ... | 2006 | 16964520 |
| 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 ... | 2006 | 16995629 |
| 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 ... | 2006 | 17001532 |
| 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 ... | 2006 | 17064264 |
| 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 ... | 2006 | 17080940 |
| 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 ... | 2006 | 16333667 |
| 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 ... | 2006 | 16452074 |
| 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 ... | 2006 | 16473891 |
| black teeth: beauty or caries prevention? practice and beliefs of the kammu people. | to 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. | 2006 | 16515671 |
| [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 ... | 2006 | 16521544 |
| 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 ... | 2006 | 16540218 |
| 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 ... | 2006 | 16640599 |
| 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 ... | 2006 | 16651250 |
| 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 ... | 2006 | 16203721 |
| 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.]. ... | 2006 | 16699911 |
| 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 ... | 2006 | 16740498 |
| 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 ... | 2006 | 16749428 |
| [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, ... | 2006 | 16756118 |
| 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 ... | 2006 | 16774929 |
| root penetration through sealing layers at mine deposit sites. | to 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 ... | 2006 | 17253002 |
| 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 ... | 2006 | 17962750 |
| [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 ... | 2005 | 16209198 |
| does the commonly used estimator of nutrient resorption in tree foliage actually measure what it claims to? | a descriptive temporal model is considered to be the best available estimator for accretion, resorption and proportional nutrient resorption. however, ecological studies rarely collect sufficient data for applying such a model. a less-demanding and commonly used estimator for proportional resorption (pr) calculates pr as the percentage of the nutrient pool that is withdrawn from mature foliage before leaf abscission. data from an intensive sampling campaign of the aboveground nutrient pools and ... | 2005 | 15891824 |
| control of cytochrome b6f at low and high light intensity and cyclic electron transport in leaves. | the light-dependent control of photosynthetic electron transport from plastoquinol (pqh(2)) through the cytochrome b(6)f complex (cyt b(6)f) to plastocyanin (pc) and p700 (the donor pigment of photosystem i, psi) was investigated in laboratory-grown helianthus annuus l., nicotiana tabaccum l., and naturally-grown solidago virgaurea l., betula pendula roth, and tilia cordata p. mill. leaves. steady-state illumination was interrupted (light-dark transient) or a high-intensity 10 ms light pulse was ... | 2005 | 15949986 |
| the chemistry of soils, rocks and plant bioindicators in three ecosystems of the holy cross mountains, poland. | in 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 ... | 2005 | 16308778 |
| 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 ... | 2005 | 16329927 |
| effects of light availability versus hydraulic constraints on stomatal responses within a crown of silver birch. | responses of leaf conductance (gl) to variation in photosynthetic photon flux density (qp), leaf-to-air vapour pressure difference (vpd), bulk leaf water potential (psi(x)), and total hydraulic conductance (gt) were examined in silver birch (betula pendula roth) with respect to leaf position in the crown. to reduce limitations caused by insufficient water supply or low light availability, experiments were also performed with branchlets cut from two different canopy layers. the intact upper-canop ... | 2005 | 15517405 |
| effects of seed origin and sowing time on timing of height growth cessation of betula pendula seedlings. | we studied the effects of seed origin and sowing time on height development and timing of height growth cessation of first-year silver birch (betula pendula roth) seedlings in a greenhouse experiment. seeds of seven origins ranging in latitudes from 58 degrees to 67 degrees n were sown at 1-2-week intervals eight times from may 21 to july 30, 2001. the day/night temperature in the greenhouse was set at 20/10 degrees c, but lighting was natural and day length varied accordingly. seedling height w ... | 2005 | 15519991 |
| role of nutrient level and defoliation on symbiotic function: experimental evidence by tracing 14c/15n exchange in mycorrhizal birch seedlings. | high nutrient availability and defoliation generally reduce ectomycorrhizal colonization levels in trees, but it is not known how this affects the functional aspects of mycorrhizal symbiosis. it was therefore investigated whether (1) defoliation or increasing substrate n availability reduce c allocation from the plant to the fungus and n allocation from the fungus to the plant (symbiotic resource exchange), (2) symbiotic resource exchange depends on relative n and p availability, and (3) fungal ... | 2005 | 15558328 |
| variations in phenology and growth of european white birch (betula pendula) clones. | phenology can have a profound effect on growth and climatic adaptability of northern tree species. although the large interannual variations in dates of bud burst and growth termination have been widely discussed, little is known about the genotypic and spatial variations in phenology and how these sources of variation are related to temporal variation. we measured bud burst of eight white birch (betula pendula roth) clones in two field experiments daily over 6 years, and determined the terminat ... | 2005 | 15574401 |
| identification of genes differentially expressed in extraradical mycelium and ectomycorrhizal roots during paxillus involutus-betula pendula ectomycorrhizal symbiosis. | the development of ectomycorrhizal symbiosis leads to drastic changes in gene expression in both partners. however, little is known about the spatial regulation of symbiosis-regulated genes. using cdna array profiling, we compared the levels of expression of fungal genes corresponding to approximately 1,200 expressed sequenced tags in the ectomycorrhizal root tips (ecm) and the connected extraradical mycelium (em) for the paxillus involutus-betula pendula ectomycorrhizal association grown on pea ... | 2005 | 15640212 |
| prevention of flower development in birch and other plants using a bpfull1::barnase construct. | the prevention of flower formation is important for avoiding the spread of transgenes from genetically modified plants into wild populations. moreover, the resources not expended for the generation of flowers and fruits might be allocated to increased vegetative growth. we have been developing methods for preventing flower formation in silver birch (betula pendula), a tree species of considerable economical importance in the boreal region. here we study the suitability of the promoter of bpfruit ... | 2005 | 15690161 |
| components of apoplastic ascorbate use in betula pendula leaves exposed to co2 and o3 enrichment. | here, the aim was to estimate loads imposed on the apoplastic ascorbate (asc) pool by enzymatic and nonenzymatic reactions in betula pendula exposed to doubled co2 and o3 concentrations in open-top chambers. leaf apoplastic extracts were analysed for peroxidase and oxidase activities in vitro, using different substrates. partial loads in vivo were deduced using measured kinetic constants and substituted-enzyme catalysis approaches. ascorbate use in o3 scavenging was calculated using measured sto ... | 2005 | 15720628 |
| leaf photosynthetic characteristics of silver birch during three years of exposure to elevated concentrations of co2 and o3 in the field. | effects of elevated concentrations of carbon dioxide ([co2]) and ozone ([o3]) on photosynthesis and related biochemistry of two european silver birch (betula pendula roth) clones were studied under field conditions during 1999-2001. seven-year-old trees of clones 4 and 80 were exposed for 3 years to the following treatments in an open-top chamber experiment: outside control (oc), chamber control (cc), 2x ambient [co2] (ec), 2x ambient [o3] (eo) and 2x ambient [co2] + 2x ambient [o3] (ec+eo). dur ... | 2005 | 15741148 |
| effects of soil temperature and elevated atmospheric co2 concentration on gas exchange, in vivo carboxylation and chlorophyll fluorescence in jack pine and white birch seedlings. | one-year-old jack pine (pinus banksiana lamb.) and current-year white birch (betula papyrifera marsh.) seedlings were grown in ambient (360 ppm) or twice ambient (720 ppm) atmospheric co2 concentration ([co2]) and at three soil temperatures (tsoil = 7, 17 and 27 degrees c initially, increased to 10, 20 and 30 degrees c two months later, respectively) in a greenhouse for 4 months. in situ foliar gas exchange, in vivo carboxylation characteristics and chlorophyll fluorescence were measured after 2 ... | 2005 | 15741153 |
| temperature dependence of leaf-level co2 fixation: revising biochemical coefficients through analysis of leaf three-dimensional structure. | co2 fixation in a leaf is determined by biochemical and physical processes within the boundaries set by leaf structure. traditionally determined temperature dependencies of biochemical processes include physical processes related to co2 exchange that result in inaccurate estimates of parameter values. a realistic three-dimensional model of a birch (betula pendula) leaf was used to distinguish between the physical and biochemical processes affecting the temperature dependence of co2 exchange, to ... | 2005 | 15760364 |
| isolation of wood-inhabiting fungi from canadian hardwood logs. | wood-inhabiting fungi include many molds, wood-staining fungi, and decay fungi. most of these fungal species can result in economic losses to wood users. studies on molds, staining fungi, and decay fungi are necessary to be able to control their growth on wood and wood products. in this study, wood-inhabiting fungi were isolated from logs of 3 major canadian hardwood species: sugar maple, white birch, and yellow birch. two media were used for isolation. from these 3 wood species, a total of 1198 ... | 2005 | 15782228 |
| [effects of natural and artificial defoliations on the content and composition of extractive substances in birch leaves]. | qualitative and quantitative compositions of extracts of birch (betula pendula roth.) leaves after natural and artificial defoliations were studied. composition of the fraction of total lipids was determined. overall, 11 fatty acids were identified. differences between the fatty acid compositions of total lipids in the trees subjected to defoliation, consisting in the increase in quantities of short-chain saturated fatty acids and trienoic acids, were detected. nine individual compounds--six fla ... | 2005 | 15810741 |
| 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 ... | 2005 | 15971066 |
| 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 ... | 2005 | 15996959 |
| 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 ... | 2005 | 15998408 |
| 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 ... | 2005 | 16042012 |
| 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 ... | 2005 | 16094429 |
| 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 ... | 2005 | 16124246 |
| 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 ... | 2005 | 16137942 |
| 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 ... | 2005 | 16139833 |
| 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 ... | 2005 | 16187111 |
| 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 ... | 2005 | 16195842 |
| essential oil of betula pendula roth. buds. | the essential oil of betula pendula roth. buds was obtained using both hydrodistillation and microdistillation techniques and their chemical compositions were analyzed using both gas chromatography (gc) and gas chromatography-mass spectrometry (gc-ms). overall, more than 50 compounds were identified representing 80% and 92% for hydrodistillation and microdistillation, respectively. the main components (by hydrodistillation and microdistillation, respectively) found were alpha-copaene (12% and 10 ... | 2004 | 15841263 |
| defensive effect of surface flavonoid aglycones of betula pubescens leaves against first instar epirrita autumnata larvae. | the surface of birch leaves contains glandular trichomes that secrete exudates containing flavonoid aglycones. we investigated the biological activities of white birch (betula pubescens) leaf surface exudates against larvae of the autumnal moth, epirrita autumnata, a common insect pest of birch. we found that tree-specific mortality (up to 100%) of first instar larvae correlated strongly with the tree-specific contents of surface flavonoid aglycones (r(s) = 0.905) in emerging leaves. we also fou ... | 2004 | 15672669 |
| fungi associated with shoots of silver birch (betula pendula) in scotland. | the fungi associated with diseased and healthy shoots of young, planted betula pendula were studied at five sites in scotland where crown die-back of birch is occurring. at each site, 30 diseased and 30 healthy shoots were sampled twice, with 1 yr-old shoots collected in may 2002, and 4-5-month-old shoots collected in september/october 2002. overall, 34 different fungal species were recorded, with 92 % and 60 % of all diseased and healthy shoot pieces, respectively, colonised by at least one fun ... | 2004 | 15587066 |
| 3-hydroxypropionic acid as a nematicidal principle in endophytic fungi. | 3- hydroxypropionic acid was isolated by bioactivity-guided fractionation of extracts obtained from submerged cultures of several endophytic fungi isolated from above-ground plant organs. this compound showed selective nematicidal activity against the plant-parasitic nematode meloidogyne incognita with ld50 values of 12.5-15 microg/ml. activity against the saprophytic caenorhabditis elegans was fivefold lower. no antimicrobial, cytotoxic or phytotoxic effects were observed. propionic acid and d- ... | 2004 | 15587708 |
| characterization and discrimination of pollen by raman microscopy. | the chemical characterization and discrimination of allergy-relevant pollen (common ragweed (ambrosia artemisiifolia), white birch (betula pendula), english oak (quercus robur), and european linden (tilia cordata)) has been studied by raman microscopy. spectra were obtained at different excitation wavelengths (514, 633, and 780 nm) and various methods were examined to minimize the strong fluorescence background. the use of a he-ne laser (633 nm) for excitation yields high-quality single pollen r ... | 2004 | 15605236 |
| short-day potentiation of low temperature-induced gene expression of a c-repeat-binding factor-controlled gene during cold acclimation in silver birch. | development of winter hardiness in trees is a two-stage process involving sequential perception of distinct environmental cues, short-day (sd) photoperiod and low temperature (lt). we have shown that both sd and lt are recognized by leaves of silver birch (betula pendula cv roth) leading to increased freezing tolerance, and thus leaves can be used as an experimental model to study the physiological and molecular events taking place during cold acclimation. to obtain a molecular marker for the ac ... | 2004 | 15563624 |
| the dibenzodioxocin lignin substructure is abundant in the inner part of the secondary wall in norway spruce and silver birch xylem. | a specific condensed lignin substructure, dibenzodioxocin, was immunolocalized in differentiating cell walls of norway spruce ( picea abies (l.) h. karsten) and silver birch ( betula pendula roth) xylem. a fluorescent probe, alexa 488 was used as a marker on the dibenzodioxocin-specific secondary antibody. for the detection of this lignin substructure, 25-microm cross-sections of xylem were viewed with a confocal laser-scanning microscope with fluorescein isothiocyanate fluorescence filters. in ... | 2004 | 13680231 |
| white birch (betula papyrifera marshall) foliar litter decomposition in relation to trace metal atmospheric inputs at metal-contaminated and uncontaminated sites near sudbury, ontario and rouyn-noranda, quebec, canada. | decomposition of white birch (betula papyrifera marshall) foliar litter was examined at metal-contaminated and uncontaminated sites established along gradients of soil cu, ni, pb and zn concentrations near sudbury, ontario and rouyn-noranda, quebec. over an 18-month study period, a significantly lower rate of litter mass loss was observed at the sudbury contaminated site (s1) than at the uncontaminated site (s2). this result was not duplicated at corresponding sites (rn1, rn2) in rouyn-noranda, ... | 2004 | 14553996 |
| extensive sharing of chloroplast haplotypes among european birches indicates hybridization among betula pendula, b. pubescens and b. nana. | extensive sharing of chloroplast haplotypes among the silver birch, betula pendula roth., the downy birch, b. pubescens ehrh., and the dwarf birch, b. nana l., was discovered using polymerase chain reaction-restriction fragment length polymporphism markers. the geographical component of the genetic variation was stronger than the species component: the species were not significantly different while 11% of the variation could be attributed to differentiation between the two main regions studied, ... | 2004 | 14653797 |
| boron uptake by ectomycorrhizas of silver birch. | boron (b) is an essential micronutrient for plants but it is thought not to be essential for fungi. we studied whether the extraradical mycelia of paxillus involutus in symbiosis with silver birch (betula pendula) take up b and transport it to the host plant. we grew mycorrhizal plants in flat microcosms with a partitioning wall, below which there was only extraradical mycelium. a boric acid solution enriched in 10b was applied to these mycelia. increased 10b/11b isotope ratios were subsequently ... | 2004 | 14745630 |
| transcriptional responses of paxillus involutus and betula pendula during formation of ectomycorrhizal root tissue. | in order to obtain information on genes specifically expressed in the ectomycorrhizal symbiosis, 3,555 expressed sequence tags (ests) were analyzed from a cdna library constructed from ectomycorrhiza formed between the basidiomycete paxillus involutus and birch (betula pendula). cdna libraries from saprophytically growing fungus (3,964 ests) and from axenic plants (2,532 ests) were analyzed in parallel. by clustering all the est obtained, a nonredundant set of 2,284 unique transcripts of either ... | 2004 | 14964534 |
| genotypic variation in drought response of silver birch (betula pendula): leaf water status and carbon gain. | to assess genotypic variation in drought response of silver birch (betula pendula roth), we studied the plasticity of 16 physiological traits in response to a 12-14-week summer drought imposed on four clones in two consecutive years. in a common garden experiment, 1-year-old clonal trees from regions with low (550 mm year(-1)) to high rainfall (1270 mm year(-1)) were grown in 45-l pots, and leaf gas exchange parameters, leaf water potentials, leaf osmotic potentials and leaf carbon isotope signa ... | 2004 | 14996656 |
| [polyclonal antisera to birch pollen allergen for the air allergen screening]. | the cross reactivity of the pollen allergens of birch (betula pendula), hazel (corylus avelana), alder (alnus glutinosa), wormwood (artemisia absinthium), oak (quercus robur) and ashtree (fraxinus excelsior) was studied by the methods of the enzyme immunoassay and gel diffusion with the use of rabbit polyclonal antisera (pas) prepared against birch pollen allergen. pas was shown to be greatly related to all above-mentioned allergens with the exception of oak pollen allergen. pas was found capabl ... | 2004 | 15024987 |
| a new sbp-box gene bpspl1 in silver birch (betula pendula). | the sbp-box gene family represents a group of plant-specific genes encoding putative transcription factors. thus far, sbp-domain protein binding sites have been found in the promoters of arabidopsis apetala1 and antirrhinum squamosa. a putative sbp-domain binding element has been observed in the promoter of bpmads5, a close homologue of arabidopsis fruitfull in silver birch (betula pendula). a novel sbp-box gene from birch named bpspl1 has been cloned and characterized. the nucleotide sequence o ... | 2004 | 15032847 |
| functional characterization of sepallata3 and agamous orthologues in silver birch. | the development of flowers is regulated by a complex network of transcriptional activators and repressors, many of which belong to the mads box gene family. in this study, we describe two mads box genes of silver birch (betula pendula roth), bpmads1 and bpmads6, which are similar to sepallata3 and agamous in arabidopsis thaliana, respectively. in situ hybridization showed that bpmads1 was expressed in the inflorescence meristem at a very early stage, but not later. both genes were expressed in d ... | 2004 | 15086829 |
| effect of natural and artificial defoliation on concentration and composition of extractive substances in leaves of birch (betula pendula roth.): methods of analysis and results. | 2004 | 15116567 | |
| effects of elevated concentrations of ozone and carbon dioxide on the electrical impedance of leaves of silver birch (betula pendula) clones. | effects of elevated concentrations of tropospheric ozone ([o3]) and carbon dioxide ([co2]) on leaves of two silver birch (betula pendula roth) clones were monitored for three growing seasons (1998, 1999, 2000) by means of electrical impedance spectroscopy (eis). the field trial with open-top chambers (otcs) was conducted on two clones (clone 4 and clone 80) with five treatments and four independent replicates. treatments were: (1) outside control, (2) chamber control, (3) 2x ambient [o3], (4) 2x ... | 2004 | 15123455 |
| development of leaf photosynthetic parameters in betula pendula roth leaves: correlations with photosystem i density. | the global modelling of photosynthesis is based on exact knowledge of the leaf photosynthetic machinery. the capacities of partial reactions of leaf photosynthesis develop at different rates, but it is not clear how the development of photoreactions and the calvin cycle are co-ordinated. we investigated the development of foliar photosynthesis in the temperate deciduous tree betula pendula roth. using a unique integrated optical/gas exchange methodology that allows simultaneous estimation of pho ... | 2004 | 15143439 |
| defoliation increases carbon limitation in ectomycorrhizal symbiosis of betula pubescens. | boreal forest trees are highly dependent on root-colonizing mycorrhizal fungi. since the maintenance of mycorrhizal symbiosis implies a significant carbon cost for the host plant, the loss of photosynthetic leaf area due to herbivory is expected to reduce the host investment in mycorrhizae. we tested this hypothesis in a common garden experiment by exposing ectomycorrhizal white birch (betula pubescens ehrh.) seedlings to simulated insect defoliation of 50 or 100% intensity during either the pre ... | 2004 | 15148601 |
| comparison of throughfall and soil solution chemistry between a high-density corsican pine stand and a naturally regenerated silver birch stand. | in flanders, critical loads for acidification and eutrophication are exceeded in the majority of the forest stands, and many previously nitrogen limited forest ecosystems have become nitrogen saturated. the present study investigates whether a naturally regenerated stand of silver birch (betula pendula roth) contributes less to the acidification and eutrophication of the forest soil than a high-density plantation of corsican pine (pinus nigra ssp. laricio maire). throughfall deposition of inorga ... | 2004 | 15210279 |
| field performance of chitinase transgenic silver birches (betula pendula): resistance to fungal diseases. | a field trial of 15 transgenic birch lines expressing a sugar beet chitinase iv gene and the corresponding controls was established in southern finland to study the effects of the level of sugar beet chitinase iv expression on birch resistance to fungal diseases. the symptoms caused by natural infections of two fungal pathogens, pyrenopeziza betulicola (leaf spot disease) and melampsoridium betulinum (birch rust), were analysed in the field during a period of 3 years. the lines that had shown a ... | 2004 | 15221141 |
| seasonal and within-stem variations of neutral lipids in silver birch (betula pendula) wood. | neutral lipids were analyzed in stem wood of a 7-year-old clone and in five 35-70-year-old mature trees of silver birch (betula pendula roth). in young trees and in mature wood of old trees, the free fatty acid fraction comprised less than 5% of the concentration of triacylglycerols (tg). the concentration of free linoleic acid was lowest in march when the young trees were dormant and highest during midsummer and september. in mature trees, the tg concentration increased toward the pith, indicat ... | 2004 | 15234896 |
| changes in leaf trichomes and epicuticular flavonoids during leaf development in three birch taxa. | changes in number of trichomes and in composition and concentrations of their exudates throughout leaf development may have important consequences for plant adaptation to abiotic and biotic factors. in the present study, seasonal changes in leaf trichomes and epicuticular flavonoid aglycones in three finnish birch taxa (betula pendula, b. pubescens ssp. pubescens, and b. pubescens ssp. czerepanovii) were followed. | 2004 | 15238348 |
| evidence that fungal pathogens inhibit recruitment of a shade-intolerant tree, white birch ( betula papyrifera), in understory habitats. | evidence from tropical forests suggests understory habitats are associated with a high risk of disease, which may prevent the establishment of vulnerable tree species; in contrast, canopy gaps can act as refuges from these pathogens. however, few studies have investigated the impacts of pathogens on regeneration in temperate forests. to determine whether losses to fungi of seeds of betula papyrifera, a light-loving species, varied between habitats that differed in their degree of openness, we ap ... | 2004 | 15243795 |
| investigating the history of prehistoric glues by gas chromatography-mass spectrometry. | although organic materials are very sensitive to biochemical alteration processes, they may be preserved for millennia in various archaeological contexts. remains of adhesives made during prehistory were discovered at different sites, in the form of residues adhering to flint tools and ceramic vessels or as free lumps in sediment. to characterise the natural substances exploited for adhesive production during late prehistory, we undertook gc and gc/ms analysis of 90 samples from 8 sites dating f ... | 2004 | 15334911 |
| silver birch and climate change: variable growth and carbon allocation responses to elevated concentrations of carbon dioxide and ozone. | we studied the effects of elevated concentrations of carbon dioxide ([co2]) and ozone ([o3]) on growth, biomass allocation and leaf area of field-grown o3-tolerant (clone 4) and o3-sensitive clones (clone 80) of european silver birch (betula pendula roth) trees during 1999-2001. seven-year-old trees of clones 4 and 80 growing outside in open-top chambers were exposed for 3 years to the following treatments: outside control (oc); chamber control (cc); 2 x ambient [co2] (ec); 2 x ambient [o3] (eo) ... | 2004 | 15339732 |
| [investigation of daily mitotic activity of the birch, betula pendula roth]. | a study was made of the daily mitotic activity in the seedling root meristem of birch trees growing in an ecologically clear area--the biological station of voronezh state university "venevitinovo". the peak of mitotic activity was exposed at 9 a. m. (according to winter time). the rise of mitotic index was noted at 9 and 12 p. m. due to an increase in the share of cells being in the prophase stage, and to a high number of dividing cells with persistent nucleoli. a possibility of prolongation of ... | 2004 | 15341127 |
| dendroremediation of trinitrotoluene (tnt). part 1: literature overview and research concept. | for decades, very large areas of former military sites have been contaminated diffusely with the persistent nitroaromatic explosive 2,4,6-trinitrotoluene (tnt). the recalcitrance of the environmental hazard tnt is to a great extent due to its particulate soil existence, which leads to slow but continuous leaching processes. although improper handling during the manufacture of tnt seems to be a problem of the past in developed countries, environmental deposition of tnt and other explosives is sti ... | 2004 | 15341318 |
| ecology and molecular characterization of dark septate fungi from roots, living stems, coarse and fine woody debris. | the aim of the present work was to determine the identity and molecular relationships between 127 strains of dark septate (ds) fungi isolated from healthy root tips, decayed coarse roots, live healthy-looking stems, coarse (stumps, snags and logs) and fine (tree branches and tops) woody debris in temperate-boreal forests in sweden and lithuania. sequence analysis of its rdna was used to identify the fungi. in a neighbour-joining similarity tree, all sequences were grouped into five distinct clus ... | 2004 | 15449602 |
| reductive titration of photosystem i and differential extinction coefficient of p700+ at 810-950 nm in leaves. | we describe a method of reductive titration of photosystem i (psi) density in leaves by generating a known amount of electrons (e-) in photosystem ii (psii) and measuring the resulting change in optical signal as these electrons arrive at pre-oxidized psi. the method complements a recently published method of oxidative titration of psi donor side e- carriers p700, plastocyanin (pc) and cytochrome f by illuminating a darkened leaf with far-red light (frl) [v. oja, h. eichelmann, r.b. peterson, b. ... | 2004 | 15450960 |
| [cytogenetic characteristics of seed offspring of leafy tree plants from one-kilometer zone of novovoronezh nuclear power station]. | cytogenetic characteristics (mitotic activity, level and spectrum of pathological mitoses, nucleoly characteristics) of seed offspring of quercus robur l. and betula pendula roth from novovoronezh nuclear power station's 1-kilometer zone have been studied. it has been shown the change of time of passing though mitotic stages by cells, the increasing of bridges frequency occur in spectrum of mitotic aberrations (that shows activation of reparation systems), the change in nucleoly characteristics ... | 2004 | 15455676 |
| allergy vaccine engineering: epitope modulation of recombinant bet v 1 reduces ige binding but retains protein folding pattern for induction of protective blocking-antibody responses. | human type 1 immediate allergic response symptoms are caused by mediator release from basophils and mast cells. this event is triggered by allergens aggregating preformed ige abs bound to the high-affinity receptor (fcepsilonri) on these cells. thus, the allergen/ige interaction is crucial for the cascade leading to the allergic and anaphylactic response. two genetically engineered forms of the white birch pollen major allergen bet v 1 with point mutations directed at molecular surfaces have bee ... | 2004 | 15470071 |
| white birch. | 2003 | 14582806 | |
| maintenance and impacts of an inoculated mer/luc-tagged pseudomonas fluorescens on microbial communities in birch rhizospheres developed on humus and peat. | antagonistic bacteria represent promising biocontrol agents for improving forest production in seedling nurseries or forest soils. the fate of an introduced mer/luc-tagged antagonistic pseudomonas fluorescens 31k3 was monitored in the rhizosphere of silver birch (betula pendula) seedlings grown in microcosms containing forest humus or nursery peat. the inoculated strain (10(8) cfu g(-1) soil) was unable to establish in significant numbers in either soil type and turned nonculturable in humus. de ... | 2003 | 12447585 |
| genotypic variation in growth and resistance to insect herbivory in silver birch (betula pendula) seedlings. | if herbivory is unevenly distributed among different types of plants, or if individual plants differ in their response to herbivory, herbivores may affect seedling growth and survival, and consequently plant population structure. in this study we examined variation in resistance to insect herbivory and in growth responses to feeding among 20 silver birch (betula pendula roth) genotypes representing variation within a natural population. birch seedlings were grown in dense stands in random arrang ... | 2003 | 14513349 |
| new oleanene and fernane-type triterpenes from the stem bark of betula pendula roth. | a new oleanene-type triterpene, named betuloleanolic acid acetate and fernane-type triterpenes, namely betufernanediol a and betufernanediol b (isomers) have been isolated from the stem bark of betula pendula. their structures have been established as olean-12-en-3beta-ylacetate-29-oic acid, fern-22(29)-en-3beta,12beta-diol and fem-22(29)-en-3alpha,12beta-diol, respectively, on the basis of spectral data analysis and chemical reactions. | 2003 | 14531469 |
| high autumn temperature delays spring bud burst in boreal trees, counterbalancing the effect of climatic warming. | the effect of temperature during short-day (sd) dormancy induction was examined in three boreal tree species in a controlled environment. saplings of betula pendula roth, b. pubescens ehrh. and alnus glutinosa (l.) moench. were exposed to 5 weeks of 10-h sd induction at 9, 15 and 21 degrees c followed by chilling at 5 degrees c for 40, 70, 100 and 130 days and subsequent forcing at 15 degrees c in a 24-h photoperiod for 60 days. in all species and with all chilling periods, high temperature duri ... | 2003 | 14532017 |
| influence of elevated co2 and o3 on betula pendula roth crown structure. | elevated co(2) and ozone effects were studied singly and in combination on the crown structure of two betula pendula clones. measurements were made at the end of the second fumigation period in an open-top-chamber experiment with 9-year-old trees. shoot ramification (number of long and short daughter shoots), shoot length, and number of metamers, leaves and buds were measured at four positions in every tree. as a result of increased temperature, trees in chambers had longer shoots and more frequ ... | 2003 | 12646500 |
| microbial impacts on plant-herbivore interactions: the indirect effects of a birch pathogen on a birch aphid. | the role of indirect interactions in structuring communities is becoming increasingly recognised. plant fungi can bring about changes in plant chemistry which may affect insect herbivores that share the same plant, and hence the two may interact indirectly. this study investigated the indirect effects of a fungal pathogen ( marssonina betulae) of silver birch ( betula pendula) on an aphid ( euceraphis betulae), and the processes underpinning the interaction. there was a strong positive associati ... | 2003 | 12647147 |
| different responses of northern and southern ecotypes of betula pendula to exogenous aba application. | we investigated responses of northern and southern ecotypes of silver birch (betula pendula roth) to exogenous abscisic acid (aba) under controlled environmental conditions to determine the role of aba in cold acclimation and dormancy development. abscisic acid was sprayed on the leaves and changes in freezing tolerance, determined by the electrolyte leakage test, and bud dormancy were monitored. applied aba induced cold acclimation but had no effect on growth cessation in seedlings grown in lon ... | 2003 | 12670802 |
| 137cs distribution among annual rings of different tree species contaminated after the chernobyl accident. | the distributions of 137cs among annual rings of pinus sylvestris and betula pendula at four experimental sites located in the most contaminated areas in the russian territory after the chernobyl accident in 1986 were studied. trees of different ages were sampled from four forest sites with different tree compositions and soil properties. the data analysis shows that 137cs is very mobile in wood and the 1986 rings do not show the highest contamination. the difference between pine and birch in th ... | 2003 | 12683726 |
| physiology-based phenology models for forest tree species in germany. | models of phenology are needed for the projection of effects of a changing climate on, for example, forest production, species competition, vegetation-atmosphere feedback and public health. a new phenology model for deciduous tree bud burst is developed and parameters are determined for a wide geographical range (germany) and several forest tree species. the new model is based on considerations of simple interactions between inhibitory and promotory agents that are assumed to control the develop ... | 2003 | 12698325 |
| comparative analysis of leaf trichome structure and composition of epicuticular flavonoids in finnish birch species. | the morphology, ultrastructure, density and distribution of trichomes on leaves of betula pendula, b. pubescens ssp. pubescens, b. pubescens ssp. czerepanovii and b. nana were examined by means of light, scanning and transmission electron microscopy. the composition of flavonoids in ethanolic leaf surface extracts was analysed by high pressure liquid chromatography. all taxa examined contained both glandular and non-glandular trichomes (short and/or long hairs) but differed from each other in tr ... | 2003 | 12714363 |
| ethylene insensitivity modulates ozone-induced cell death in birch. | we have used genotypic variation in birch (betula pendula roth) to investigate the roles of ozone (o(3))-induced ethylene (et), jasmonic acid, and salicylic acid in the regulation of tissue tolerance to o(3). of these hormones, et evolution correlated best with o(3)-induced cell death. disruption of et perception by transformation of birch with the dominant negative mutant allele etr1-1 of the arabidopsis et receptor gene etr1 or blocking of et perception with 1-methylcyclopropene reduced but di ... | 2003 | 12746524 |
| physiological responses of birch (betula pendula) to ozone: a comparison between open-soil-grown trees exposed for six growing seasons and potted seedlings exposed for one season. | physiological responses of 4-year-old potted saplings of an o3-tolerant clone of betula pendula roth to short-term ozone (o3) exposure (one growing season) were compared with those of 6-year-old open-soil-grown trees of the same clone fumigated with o3 for six growing seasons. in the 2001 growing season, both groups of plants were exposed to ambient (control) and 1.6x ambient (elevated) o3 concentration under similar microclimatic conditions in a free air o3 exposure facility. growth, net photos ... | 2003 | 12750053 |
| impact of ozone on the growth of birch (betula pendula) saplings. | saplings of one half-sib family of birch, betula pendula, were exposed to three levels of ozone in open-top chambers (otcs) during two growing seasons 1997-1998. the ozone treatments were non-filtered air (nf, accumulated daylight aot40 over the two growing seasons of 3.0 l l-1 h), non-filtered air with extra ozone (nf+, accumulated daylight aot40 of 27.3 l l-1 h) and non-filtered air with additional extra ozone (nf++, accumulated daylight aot40 of 120 l l-1 h). the birch saplings, including the ... | 2003 | 12758028 |
| development and recovery from winter embolism in silver birch: seasonal patterns and relationships with the phenological cycle in oceanic scotland. | silver birch (betula pendula roth) is increasingly used in the united kingdom for reforestation. however, recent evidence indicates that, under some circumstances, planted birch can suffer serious and repeated mortality of the apical leaders and branches, with consequent loss of apical dominance and the formation of a contorted stem. plants from 37 seed sources of silver birch from scotland and northern england planted at two sites were compared for several characteristics related to hydraulic a ... | 2003 | 12777239 |
| responses of selected birch (betula pendula roth) clones to ozone change over time. | a long-term free air ozone fumigation experiment was conducted to study changes in physiological ozone responses during tree ontogeny and exposure time in ozone sensitive and tolerant clones of european white birch (betula pendula roth), originated from south and central finland. the trees were grown in soil in natural microclimatic conditions under ambient ozone (control) and 1.4-1.7 x ambient (elevated) ozone from may 1996 to october 2001, and were measured for stem and foliage growth, net pho ... | 2003 | 12803615 |
| silver birch (betula pendula) plants with aux and rol genes show consistent changes in morphology, xylem structure and chemistry. | the effects of agrobacterium pria4 rol and aux genes, controlled by their endogenous promoters, on tree growth and wood anatomy and chemistry were studied in 5- and 7-year-old silver birch (betula pendula roth) plants. southern hybridization confirmed the following rol and aux gene combinations: control plants (no genes transferred); plants with rolc and rold genes; plants with rola, rolb, rolc and rold genes; and plants with rola, rolb, rolc, rold, aux1 and aux2 genes. transgene mrna was most a ... | 2003 | 12839726 |
| betulinic acid-induced programmed cell death in human melanoma cells involves mitogen-activated protein kinase activation. | betulinic acid, a naturally occurring triterpene found in the bark of the white birch tree, has been demonstrated to induce programmed cell death with melanoma and certain neuroectodermal tumor cells. we demonstrate currently that treatment of cultured uiso-mel-1 (human melanoma cells) with betulinic acid leads to the activation of p38 and stress activated protein kinase/c-jun nh(2)-terminal kinase [widely accepted proapoptotic mitogen-activated protein kinases (mapks)] with no change in the pho ... | 2003 | 12855667 |
| developmental lignification and seasonal variation in beta-glucosidase and peroxidase activities in xylem of scots pine, norway spruce and silver birch. | we examined the relationship between beta-glucosidase and peroxidase activities and xylem lignification in the stems of scots pine (pinus sylvestris l.), norway spruce (picea abies (l.) karst.) and silver birch (betula pendula roth) during the 1999 growing season. examination of stem cross sections stained with safranin and alcian blue for lignin and cellulose, respectively, indicated that radial growth of pine and spruce xylem began in late may, whereas the growth of birch xylem was initiated 2 ... | 2003 | 12952784 |