| phylogeny of chitinases and its implications for estimating horizontal gene transfer from chitinase-transgenic silver birch (betula pendula). | chitinases are hydrolytic enzymes that have been employed in biotechnology in attempts to increase plants' resistance against fungal pathogens. genetically modified plants have given rise to concerns of the spreading of transgenes into the environment through vertical or horizontal gene transfer (hgt). in this study, chitinase-like sequences from silver birch (betula pendula) est-libraries were identified and their phylogenetic relationships to other chitinases were studied. phylogenetic analyse ... | 2008 | 19081010 |
| optimization of ultrasonic-assisted extraction (uae) of betulin from white birch bark using response surface methodology. | betulin is an abundant naturally occurring triterpene, which makes it a potentially important raw material for a precursor of biologically active compounds. the objective of the current study was to determine the optimum uae conditions for betulin from b. papyfera bark. the optimum conditions were evaluated with fractional factorial design and optimized using response surface methodology. high yields of betulin were observed from white birch bark by uae technology. the solvent concentration and ... | 2009 | 19110462 |
| [on the competition among discrete-structured populations: a matrix model for population dynamics of woodreed and birch growing together]. | presented is a synthesis of field, theoretical and modelling studies on joint dynamics of two species--common birch (betula pendula roth) and wood small reed (calamagrostis epigeios (l.) roth)--overgrowing a spruce forest clear-cut. a nonlinear matrix model for population dynamics of two species, which both possess non-trivial population structures and compete for a resource in common was developed as an expansion of the linear models for single-species, age-stage-structured population dynamics. ... | 2008 | 19140335 |
| pollen allergenic potential nature of some trees species: a multidisciplinary approach using aerobiological, immunochemical and hospital admissions data. | trees are considered producers of allergenic pollen. the aims of this work were to characterize the aerobiology of the platanus, acer, salix, quercus, betula and populus pollen, linking it with monthly emergency hospital admissions and to identify the different reactivity levels in sensitized patients. this information would be of great importance to evaluate the convenience of changing the inventory of pollen producer trees related to the risk of allergenic reactions. the study was conducted in ... | 2009 | 19147130 |
| density and composition of an insect population in a field trial of chitinase transgenic and wild-type silver birch (betula pendula) clones. | fifteen silver birch (betula pendula roth) lines carrying a sugar beet chitinase iv gene and eight wild-type birch clones were grown in a field trial. the composition and density of the insect population and the leaf damage caused by insects were monitored and compared between transgenic and wild-type trees. the most abundant insect group in all trees was aphids, and the variation in total insect densities was mainly explained by the variation in aphid densities. insect densities were generally ... | 2008 | 19161703 |
| a comparison of phenological models of leaf bud burst and flowering of boreal trees using independent observations. | we compared and tested thermal time, sequential, parallel and flexible phenological models of leaf bud burst in birch (betula pendula roth. and b. pubescens ehrh.) and flowering in bird cherry (prunus padus l.) and rowan (sorbus aucuparia l.). we used phenological records from oulainen-ohineva (64 degrees 13' n, 24 degrees 53' e) in central finland from 1953 to 2002 to estimate model parameters. we tested the models with data collected in all but six years between 1896 and 2002 in southern and c ... | 2008 | 19193570 |
| characterization of pr-10 genes from eight betula species and detection of bet v 1 isoforms in birch pollen. | bet v 1 is an important cause of hay fever in northern europe. bet v 1 isoforms from the european white birch (betula pendula) have been investigated extensively, but the allergenic potency of other birch species is unknown. the presence of bet v 1 and closely related pr-10 genes in the genome was established by amplification and sequencing of alleles from eight birch species that represent the four subgenera within the genus betula. q-tof lc-mse was applied to identify which pr-10/bet v 1 genes ... | 2009 | 19257882 |
| identification and isolation of pharmacologically active triterpenes in betuale cortex, betula pendula roth., betulaceae. | betulae cortex, betula pendula roth., betulaceae, comprise triterpene substances which are confirmed to posses very important pharmacological activities such as anti-inflammatory, anticancer and antiviral. in this study, extraction of triterpene substances from both, inner and external birch bark was carried out and after that qualitative analysis on betulin, betulinic acid, oleanolic acid and lupeol was performed by method of thin layer chromatography. by this separation method, applying system ... | 2009 | 19284392 |
| fire drives transcontinental variation in tree birch defense against browsing by snowshoe hares. | fire has been the dominant disturbance in boreal america since the pleistocene, resulting in a spatial mosaic in which the most fire occurs in the continental northwest. spatial variation in snowshoe hare (lepus americanus) density reflects the fire mosaic. because fire initiates secondary forest succession, a fire mosaic creates variation in the abundance of early successional plants that snowshoe hares eat in winter, leading to geographic variation in hare density. we hypothesize that fire is ... | 2009 | 19422319 |
| variation in host specificity and gene content in strains from genetically isolated lineages of the ectomycorrhizal fungus paxillus involutus s. lat. | ectomycorrhizal fungi are known to vary in host range. some fungi can enter into symbiosis with multiple plant species, while others have restricted host ranges. the aim of this study was to examine variation in host specificity among strains from the basidiomycete paxillus involutus s. lat. recent studies have shown that this fungus consists of at least four genetically isolated lineages, phylogenetic species (ps) i (which corresponds to the morphological species paxillus obscurosporus), ps ii ... | 2009 | 19452174 |
| interactive effect of elevated temperature and o3 on antioxidant capacity and gas exchange in betula pendula saplings. | we studied the effects of slightly elevated temperature (t), o(3) concentration (o(3)) and their combination (t + o(3)) on the antioxidant defense, gas exchange and total leaf area of betula pendula saplings in field conditions. during the second year of the experiment, t enhanced the total leaf area, net photosynthesis (p (n)) and maximum capacity of carboxylation, redox state of ascorbate and total antioxidant capacity in the apoplast. o(3) did not affect the total leaf area, but p (n) was sli ... | 2009 | 19484475 |
| life-history strategies affect aphid preference for yellowing leaves. | according to the nutrient-translocation hypothesis, yellowing tree leaves are colonized by aphids at the end of the growing season owing to improved availability of nutrients in the phloem sap after chlorophyll degradation. we measured aphid densities on potted betula pendula seedlings in a field site where a small proportion of foliage rapidly turned yellow before normal autumn coloration as a consequence of root anoxia. the number of adults and nymphs of the birch-feeding specialist aphids euc ... | 2009 | 19535364 |
| solar ultraviolet radiation alters alder and birch litter chemistry that in turn affects decomposers and soil respiration. | solar ultraviolet (uv)-a and uv-b radiation were excluded from branches of grey alder (alnus incana) and white birch (betula pubescens) trees in a field experiment. leaf litter collected from these trees was used in microcosm experiments under laboratory conditions. the aim was to evaluate the effects of the different uv treatments on litter chemical quality (phenolic compounds, c, n and lignin) and the subsequent effects of these changes on soil fauna and decomposition processes. we measured th ... | 2009 | 19597848 |
| rubisco in planta kcat is regulated in balance with photosynthetic electron transport. | site turnover rate (k(cat)) of rubisco was measured in intact leaves of different plants. potato (solanum tuberosum l.) and birch (betula pendula roth.) leaves were taken from field-growing plants. sunflower (helianthus annuus l.), wild type (wt), rubisco-deficient (-rbc), fnr-deficient (-fnr), and cyt b(6)f deficient (-cbf) transgenic tobacco (nicotiana tabacum l.) were grown in a growth chamber. rubisco protein was measured with quantitative sds-page and fnr protein content with quantitative i ... | 2009 | 19661266 |
| growth of frankia strains in leaf litter-amended soil and the rhizosphere of a nonactinorhizal plant. | the ability of frankia strains to grow in the rhizosphere of a nonactinorhizal plant, betula pendula, in surrounding bulk soil and in soil amended with leaf litter was analyzed 6 weeks after inoculation of pure cultures by in situ hybridization. growth responses were related to taxonomic position as determined by comparative sequence analysis of nifh gene fragments and of an actinomycetes-specific insertion in domain iii of the 23s rrna gene. phylogenetic analyses confirmed the basic classificat ... | 2009 | 19678845 |
| assessment of uv biological spectral weighting functions for phenolic metabolites and growth responses in silver birch seedlings. | in research concerning stratospheric ozone depletion, action spectra are used as biological spectral weighting functions (bswfs) for describing the effects of uv radiation on plant responses. our aim was to evaluate the appropriateness of six frequently used bswfs that differ in effectiveness with increasing wavelength. the evaluation of action spectra was based on calculating the effective uv radiation doses according to 1-2) two formulations of the generalized plant action spectrum, 3) a spect ... | 2009 | 19682323 |
| effects of sugar beet chitinase iv on root-associated fungal community of transgenic silver birch in a field trial. | heterogenous chitinases have been introduced in many plant species with the aim to increase the resistance of plants to fungal diseases. we studied the effects of the heterologous expression of sugar beet chitinase iv on the intensity of ectomycorrhizal (ecm) colonization and the structure of fungal communities in the field trial of 15 transgenic and 8 wild-type silver birch (betula pendula roth) genotypes. fungal sequences were separated in denaturing gradient gel electrophoresis and identified ... | 2009 | 19697057 |
| phenolic compounds in ectomycorrhizal interaction of lignin modified silver birch. | the monolignol biosynthetic pathway interconnects with the biosynthesis of other secondary phenolic metabolites, such as cinnamic acid derivatives, flavonoids and condensed tannins. the objective of this study is to evaluate whether genetic modification of the monolignol pathway in silver birch (betula pendula roth.) would alter the metabolism of these phenolic compounds and how such alterations, if exist, would affect the ectomycorrhizal symbiosis. | 2009 | 19788757 |
| interactions of ectomycorrhizas and above-ground insect herbivores on silver birch. | | 2009 | 19794863 |
| low moisture availability inhibits the enhancing effect of increased soil temperature on net photosynthesis of white birch (betula papyrifera) seedlings grown under ambient and elevated carbon dioxide concentrations. | white birch (betula papyrifera marsh.) seedlings were grown under two carbon dioxide concentrations (ambient: 360 micromol mol(-1) and elevated: 720 micromol mol(-1)), three soil temperatures (5, 15 and 25 degrees c initially, increased to 7, 17 and 27 degrees c, respectively, 1 month later) and three moisture regimes (low: 30-40%; intermediate: 45-55% and high: 60-70% field water capacity) in greenhouses. in situ gas exchange and chlorophyll fluorescence were measured after 2 months of treatmen ... | 2009 | 19797245 |
| betulin elicits anti-cancer effects in tumour primary cultures and cell lines in vitro. | betulin is a pentacyclic triterpene found in many plant species, among others, in white birch bark. the aim of the study was in vitro characterization of the anticancer activity of betulin in a range of human tumour cell lines (neuroblastoma, rhabdomyosarcoma-medulloblastoma, glioma, thyroid, breast, lung and colon carcinoma, leukaemia and multiple myeloma), and in primary tumour cultures isolated from patients (ovarian carcinoma, cervical carcinoma and glioblastoma multiforme). in this study, w ... | 2009 | 19821831 |
| [the dynamics of phenolic compounds and soluble sugars in the leaves of the silver birch (betula pendula roth) after defoliation and their significance in entomological plant resistance]. | the dynamics of phenolic compounds, flavonols, catechines, tannins, and soluble sugars in the leaves of the silver birch betula pendula roth after strong (75%) and total (100%) artificial defoliation was studied. it was shown that the flavonol content in the leaves did not change after strong and total defoliation, while the amount of tannins did not change during the first 15 days but increased later on 1 and 2 years after 75% and 100% defoliation. the catechine content did not change during th ... | 2009 | 19894597 |
| low soil temperature inhibits the effect of high nutrient supply on photosynthetic response to elevated carbon dioxide concentration in white birch seedlings. | to investigate the interactive effects of soil temperature (t(soil)) and nutrient availability on the response of photosynthesis to elevated atmospheric carbon dioxide concentration ([co(2)]), white birch (betula papyrifera marsh.) seedlings were exposed to ambient (360 micromol mol(-1)) or elevated (720 micromol mol(-1)) [co(2)], three t(soil) (5, 15 and 25 degrees c initially, increased to 7, 17 and 27 degrees c, respectively, 1 month later) and three nutrient regimes (4/1.8/3.3, 80/35/66 and ... | 2010 | 20007132 |
| determination of de novo and pool emissions of terpenes from four common boreal/alpine trees by 13co2 labelling and ptr-ms analysis. | boreal forests emit a large amount of monoterpenes into the atmosphere. traditionally these emissions are assumed to originate as evaporation from large storage pools. thus, their diurnal cycle would depend mostly on temperature. however, there is indication that a significant part of the monoterpene emission would originate directly from de novo synthesis. by applying 13co2 fumigation and analyzing the isotope fractions with proton transfer reaction mass spectrometry (ptr-ms) and classical gc-m ... | 2010 | 20040067 |
| acc oxidase genes expressed in the wood-forming tissues of loblolly pine (pinus taeda l.) include a pair of nearly identical paralogs (nips). | 1-aminocyclopropane-1-carboxylate (acc) oxidase catalyzes the final reaction of the ethylene biosynthetic pathway, converting the unusual cyclic amino acid, acc, into ethylene. past studies have shown a possible link between ethylene and compression wood formation in conifers, but the relationship has received no more than modest study at the gene expression level. in this study, a cdna clone encoding a putative acc oxidase, ptaco1, was isolated from a cdna library produced using mrna from ligni ... | 2010 | 20053371 |
| foliar methyl salicylate emissions indicate prolonged aphid infestation on silver birch and black alder. | it is well documented that when plants are damaged by insects they respond by emitting a range of volatile organic compounds (vocs). while there have been numerous reports concerning vocs induced by chewing herbivores, there are relatively few studies detailing the vocs induced by aphid feeding. the effects of aphid feeding on vocs emitted by boreal forest trees have been particularly neglected. herbivore-induced vocs have relevance to direct and indirect plant defence and atmospheric chemistry. ... | 2010 | 20097686 |
| differential gene expression in senescing leaves of two silver birch genotypes in response to elevated co2 and tropospheric ozone. | long-term effects of elevated co(2) and o(3) concentrations on gene expression in silver birch (betula pendula roth) leaves were studied during the end of the growing season. two birch genotypes, clones 4 and 80, with different ozone growth responses, were exposed to 2x ambient co(2) and/or o(3) in open-top chambers (otcs). microarray analyses were performed after 2 years of exposure, and the transcriptional profiles were compared to key physiological characteristics during leaf senescence. ther ... | 2010 | 20132521 |
| photosynthetic characteristics in genetically modified sense-rbcs silver birch lines. | transgenic silver birch lines carrying extra copies of endogenous small subunit of rubisco (rbcs)-gene under 35s camv promoter were used to study the carbon use efficiency of silver birch (betula pendula roth). a five week greenhouse experiment was carried out with four transgenic lines, r3.2, r7.2, e5 and e25, and their corresponding wild types (wt). the first fully developed leaves were used for analyses. three of the produced lines, r3.2, e5 and e25, differed from the wt lines. line r3.2 show ... | 2010 | 20171755 |
| near-ambient ozone concentrations reduce the vigor of betula and populus species in finland. | in this review the main growth responses of finnish birch (betula pendula, b. pubescens) and aspen species (populus tremula and p. tremuloides x p. tremula) are correlated with ozone exposure, indicated as the aot40 value. data are derived from 23 different laboratory, open-top chamber, and free-air fumigation experiments. our results indicate that these tree species are sensitive to increasing ozone concentrations, though high intraspecific variation exists. the roots are the most vulnerable ta ... | 2009 | 20175439 |
| rising atmospheric co2 concentration partially masks the negative effects of elevated o3 in silver birch (betula pendula roth). | this review summarizes the main results from a 3-year open top chamber experiment, with two silver birch (betula pendula roth) clones (4 and 80) where impacts of 2x ambient [co2] (ec) and [o3] (eo) and their combination (ec + eo) were examined. growth, physiology of the foliage and root systems, crown structure, wood properties, and biological interactions were assessed to understand the effects of a future climate on the biology of silver birch. the clones displayed great differences in their r ... | 2009 | 20175440 |
| elevation of night-time temperature increases terpenoid emissions from betula pendula and populus tremula. | volatile organic compounds (vocs) are expected to have an important role in plant adaptation to high temperatures. the impacts of increasing night-time temperature on daytime terpenoid emissions and related gene expression in silver birch (betula pendula) and european aspen (populus tremula) clones were studied. the plants were grown under five different night-time temperatures (6, 10, 14, 18, and 22 degrees c) while daytime temperature was kept at a constant 22 degrees c. voc emissions were col ... | 2010 | 20181662 |
| flavonol quantification and stability of phenolics in fermented extracts from fresh betula pendula leaves. | an hplc method, which allows reliable quantitation of flavonols and other phenolics in birch leaf extracts, was developed and validated. the method was applied to study the bioconversion of flavonols in fermented aqueous extracts. almost 100% of the flavonols were converted during the 12 months observation period. the generated phenolics as well as consecutive conversion products were identified by hplc-dad, lc-ms and gc-ms techniques. | 2010 | 20189738 |
| ophiostoma denticiliatum sp. nov. and other ophiostoma species associated with the birch bark beetle in southern norway. | ophiostomatoid fungi were isolated from scolytus ratzeburgi infesting betula pendula and b. pubescens in norway. fungi were identified based on morphology, dna sequence comparison for two gene regions and phylogenetic analyses. the most abundant fungus was ophiostoma karelicum, suggesting a specific relationship between the fungus, the vector insect and the host tree. our results suggest that o. karelicum occurs across the geographic range of s. ratzeburgi and its close relatedness to the dutch ... | 2009 | 20198157 |
| changes in pelagic bacteria communities due to leaf litter addition. | in many limnetic systems, the input of allochthonous organic matter, e.g., leaf litter, is a substantial source of dissolved organic carbon (doc) for pelagic bacteria, especially in fall and winter when autochthonous doc production is low. however, relatively little is known about community changes of pelagic lake bacteria due to leaf litter input which includes both the release of leaf leachates and microorganisms from the leaf litter into the surrounding water. therefore, we have experimentall ... | 2010 | 20198369 |
| birch (betula spp.) leaves adsorb and re-release volatiles specific to neighbouring plants--a mechanism for associational herbivore resistance? | plant-emitted semi-volatile compounds have low vaporization rates at 20-25 degrees c and may therefore persist on surfaces such as plant foliage. the passive adsorption of arthropod-repellent semi-volatiles to neighbouring foliage could convey associational resistance, whereby a plant's neighbours reduce damage caused by herbivores. we found that birch (betula spp.) leaves adsorb and re-release the specific arthropod-repelling c(15) semi-volatiles ledene, ledol and palustrol produced by rhododen ... | 2010 | 20298484 |
| impact of hemicellulose pre-extraction for bioconversion on birch kraft pulp properties. | the combination of hemicellulose extraction with chemical pulping processes is one approach to generate a sugar feedstock amenable to biochemical transformation to fuels and chemicals. extractions of hemicellulose from silver birch (betula pendula) wood chips using either water or kraft white liquor (naoh, na(2)s, and na(2)co(3)) were performed under conditions compatible with kraft pulping, using times ranging between 20 and 90 min, temperatures of 130-160 degrees c, and effective alkali (ea) c ... | 2010 | 20378336 |
| forage quantity, quality and depletion as scale-dependent mechanisms driving habitat selection of a large browsing herbivore. | 1. mechanisms that affect the spatial distribution of animals are typically scale-dependent and may involve forage distribution. forage quality and quantity are often inversely correlated and a much discussed trade-off is whether or not to select for high-quality forage at the expense of forage abundance. this discussion has rarely involved scale-dependence or been applied to northern browsing herbivores. at small spatial scales, browsers are assumed to select for the best quality forage. but, a ... | 2010 | 20443990 |
| pollen enzymes degrade human tear fluid and conjunctival cells: an approach to understanding seasonal non-allergic conjunctivitis. | during pollen seasons, allergy-like symptoms can be observed in proven non-allergy sufferers. pollen enzymes are thought to be responsible for conjunctival irritation. we investigated the influence of the well-known aggressive pollen species hazelnut (corylus avellana) and birch pollen (betula pendula) on both human tear fluid and conjunctival cell cultures. this study is an approach to seasonal non-allergic conjunctivitis (snac) syndrome. | 2010 | 20502029 |
| effects of solar uv-a and uv-b radiation on gene expression and phenolic accumulation in betula pendula leaves. | ultraviolet (uv) radiation is an important environmental factor for plant communities; however, plant responses to solar uv are not fully understood. here, we report differential effects of solar uv-a and uv-b radiation on the expression of flavonoid pathway genes and phenolic accumulation in leaves of betula pendula roth (silver birch) seedlings grown outdoors. plants were exposed for 30 days to six uv treatments created using three types of plastic film. epidermal flavonoids measured in vivo d ... | 2010 | 20519675 |
| seasonal fluctuations in leaf phenolic composition under uv manipulations reflect contrasting strategies of alder and birch trees. | seasonal variation in leaf phenolic composition may be important for acclimation of plants to seasonal changes in their biotic and abiotic environment. for a realistic assessment of how plants respond to solar uv-b (280-315 nm) and uv-a (315-400 nm) radiation, seasonal variation in both environment and plant responses needs to be taken into account. this also has implications for studies concerning stratospheric ozone depletion and resulting increased uv-b radiation, as other environmental varia ... | 2010 | 20626643 |
| wood anatomical analysis of alnus incana and betula pendula injured by a debris-flow event. | vessel chronologies in ring-porous species have been successfully employed in the past to extract the climate signal from tree rings. environmental signals recorded in vessels of ring-porous species have also been used in previous studies to reconstruct discrete events of drought, flooding and insect defoliation. however, very little is known about the ability of diffuse-porous species to record environmental signals in their xylem cells. moreover, time series of wood anatomical features have on ... | 2010 | 20639516 |
| ecology of coarse wood decomposition by the saprotrophic fungus fomes fomentarius. | saprotrophic wood-inhabiting basidiomycetes are the most important decomposers of lignin and cellulose in dead wood and as such they attracted considerable attention. the aims of this work were to quantify the activity and spatial distribution of extracellular enzymes in coarse wood colonised by the white-rot basidiomycete fomes fomentarius and in adjacent fruitbodies of the fungus and to analyse the diversity of the fungal and bacterial community in a fungus-colonised wood and its potential eff ... | 2010 | 20668917 |
| xanthine oxidase inhibitory properties of czech medicinal plants. | to investigate in vitro xanthine oxidase inhibitory properties of plants traditionally used in czech republic and central-east europe region for gout, arthritis or rheumatism treatment. | 2010 | 20800669 |
| leaf volatile emissions of betula pendula during autumn coloration and leaf fall. | deciduous trees remobilize the nitrogen in leaves during the process of autumn coloration, thus providing a high quality food source for aphids preparing to lay over-wintering eggs. it has been suggested that aphids may use volatile organic compounds (vocs) to: (a) select leaves where nutrient remobilization has started and induced defenses are reduced; and (b) detect the time of leaf abscission. we analyzed vocs emitted by the foliage of betula pendula roth. during autumn coloration and from le ... | 2010 | 20838885 |
| the effect of tree architecture on conduit diameter and frequency from small distal roots to branch tips in betula pendula, picea abies and pinus sylvestris. | we studied the effect of tree architecture on xylem anatomy in three betula pendula roth., three picea abies (l.) h. karst. and three pinus sylvestris (l.) trees (mean age 35 years). first, the analysis of conduit anatomy in different tree parts showed that conduits tapered and their frequency increased from roots (≥ 2 mm) to stem, from stem to branches and further to leaf petioles in b. pendula. conduit anatomy in lateral and main roots, as well as lateral and main branches, significantly diffe ... | 2010 | 21030407 |
| experimental evidence supporting the concept of light-mediated modulation of stem hydraulic conductance. | it is a well-described phenomenon that plant leaves respond to changes in light intensity and duration by adjusting leaf hydraulic efficiency, and there is current consensus that up- or down-regulation of water channels (aquaporins) in the plasma membrane of the bundle sheath and mesophyll cells play a central role in the underlying mechanisms. recently, experimental evidence has been provided also for light-mediated changes of stem hydraulic conductance (k(stem)) in field-grown laurel plants. t ... | 2010 | 21071503 |
| immunomodulatory effects of betulinic acid from the bark of white birch on mice. | the objective of this study was to explore the immunomodulatory effects of betulinic acid (ba) extracted from the bark of white birch on mice. female mice were orally administered ba for 14 days in doses of 0, 0.25, 0.5, and 1 mg/kg body weight. we found that ba significantly enhanced the thymus and spleen indices, and stimulated lymphocyte proliferation induced by concanavalin a and lipopolysaccharide as shown by mtt assay. flow cytometry revealed that ba increased the percentage of cd4(+) cell ... | 2010 | 21113099 |
| chilling of dormant buds hyperinduces flowering locus t and recruits ga-inducible 1,3-beta-glucanases to reopen signal conduits and release dormancy in populus. | in trees, production of intercellular signals and accessibility of signal conduits jointly govern dormancy cycling at the shoot apex. we identified 10 putative cell wall 1,3-ß-glucanase genes (glucan hydrolase family 17 [gh17]) in populus that could turn over 1,3-ß-glucan (callose) at pores and plasmodesmata (pd) and investigated their regulation in relation to ft and cenl1 expression. the 10 genes encode orthologs of arabidopsis thaliana bg_ppap, a pd-associated glycosylphosphatidylinositol (gp ... | 2011 | 21282527 |
| quantification of lignin-carbohydrate linkages with high-resolution nmr spectroscopy. | a quantitative approach to characterize lignin-carbohydrate complex (lcc) linkages using a combination of quantitative ¹³c nmr and hsqc 2d nmr techniques has been developed. crude milled wood lignin (mwlc), lcc extracted from mwlc with acetic acid (lcc-acoh) and cellulolytic enzyme lignin (cel) preparations were isolated from loblolly pine (pinus taeda) and white birch (betula pendula) woods and characterized using this methodology on a routine 300 mhz nmr spectrometer and on a 950 mhz spectrome ... | 2011 | 21298285 |
| proteomic profiling of birch (betula verrucosa) pollen extracts from different origins. | pollen of the european white birch is a major source of spring pollinosis in europe. pollen-allergy diagnosis and treatment by specific immunotherapy commonly rely on extracts of natural origin. to gain insight into the protein content and its variability, we evaluated the profile of allergenic and non-allergenic proteins in extracts of pollen from different origins by ms-based proteomics. aqueous extracts prepared from commercially available swedish birch pollen, pollen collected from austrian ... | 2011 | 21360672 |
| how reliable is the double-ended pressure sleeve technique for assessing xylem vulnerability to cavitation in woody angiosperms? | the reliability of a double-ended pressure sleeve technique was evaluated on three woody angiosperm species with contrasting maximum vessel lengths. vulnerability curves (vcs) were constructed by varying sample length and the size of the pressure sleeves. vcs were compared against curves obtained with reference techniques. for the two diffuse-porous species, betula pendula and prunus persica, vcs built with shoot segments shorter than maximum vessel length strongly overestimated species vulnerab ... | 2011 | 21401617 |
| impact of light quality on leaf and shoot hydraulic properties: a case study in silver birch (betula pendula). | responses of leaf and shoot hydraulic conductance to light quality were examined on shoots of silver birch (betula pendula), cut from lower ('shade position') and upper thirds of the crowns ('sun position') of trees growing in a natural temperate forest stand. hydraulic conductances of leaf blades (k(lb) ), petioles (k(p) ) and branches (i.e. leafless stem; k(b) ) were determined using a high pressure flow meter in steady state mode. the shoots were exposed to photosynthetic photon flux density ... | 2011 | 21414012 |
| proteomic analysis of the major birch allergen bet v 1 predicts allergenicity for 15 birch species. | pollen of the european and asian white birch (betula pendula and b. platyphylla) causes hay fever in humans. the allergenic potency of other birch species is largely unknown. to identify birch trees with a reduced allergenicity, we assessed the immunochemical characteristics of 15 species and two hybrids, representing four subgenera within the genus betula, while focusing on the major pollen allergen bet v 1. antigenic and allergenic profiles of pollen extracts from these species were evaluated ... | 2011 | 21459169 |
| deer browsing and soil disturbance induce cascading effects on plant communities: a multilevel path analysis. | understanding how large herbivores shape plant diversity patterns is an important challenge in community ecology, especially because many ungulate populations in the northern hemisphere have recently expanded. because species within plant communities can exhibit strong interactions (e.g., competition, facilitation), selective foraging by large herbivores is likely not only to affect the abundance of palatable species, but also to induce cascading effects across entire plant communities. to inves ... | 2011 | 21563575 |
| an aqueous birch leaf extract of betula pendula inhibits the growth and cell division of inflammatory lymphocytes. | ethnopharmacological relevance: leaf extracts of betula pendula have been traditionally used for the treatment of patients with rheumatoid arthritis (ra) or osteoarthritis. aim of the study: we investigated the anti-proliferative capacity of an aqueous leaf extract of betula pendula (bpe) on human primary lymphocytes in vitro, because activated lymphocytes play a major role in the initiation and maintenance of ra. materials and methods: lymphocyte proliferation and cell division was measured by ... | 2011 | 21619918 |
| distribution and expression characteristics of triterpenoids and osc genes in white birch (betula platyphylla suk.). | betulin and oleanolic acids (pentacyclic triterpenoid secondary metabolites) have broad pharmacological activities and can be potentially used for the development of anti-cancer and anti-aids drugs. in this study, we detected the accumulation and the distribution characteristics of betulin and oleanolic acid in various organs of white birch at different ages. we also determined the expression of 4 osc genes (lus, β-as, cas1 and cas2) involved in the triterpenoid synthesis pathways by real time r ... | 2011 | 21647548 |
| ultraviolet-b-induced flavonoid accumulation in betula pendula leaves is dependent upon nitrate reductase-mediated nitric oxide signaling. | nitric oxide (no) is an important signaling molecule involved in many physiological processes in plants. nitric oxide generation and flavonoid accumulation are two early reactions of plants to ultraviolet-b (uv-b) irradiation. however, the source of uv-b-triggered no generation and the role of no in uv-b-induced flavonoid accumulation are not fully understood. in order to evaluate the origin of uv-b-triggered no generation, we examined the responses of nitrate reductase (nr) activity and the exp ... | 2011 | 21813515 |
| bird predation enhances tree seedling resistance to insect herbivores in contrasting forest habitats. | according to the associational resistance hypothesis, neighbouring plants are expected to influence both the insect herbivore communities and their natural enemies. however, this has rarely been tested for the effects of canopy trees on herbivory of seedlings. one possible mechanism responsible for associational resistance is the indirect impact of natural enemies on insect herbivory, such as insectivorous birds. but it remains unclear to what extent such trophic cascades are influenced by the c ... | 2011 | 21811874 |
| the past, present and future tasks of hungarian dendrological research. | hungarian dendrological research (research of living woody plants) has more than 200 years old history; the first general work by j+ínos kereszt+®ly grossinger was published in 1797. further basic works in our time yet are: forest botany by lajos fekete and s+índor m+íg+¦csy-dietz (1896); and the chorological work, distribution of trees and shrubs of sylvicultural importance in the region of hungarian state by lajos fekete and tibor blattny (1913). a few dendrologists and many botanists have hel ... | 2010 | 21565760 |
| isolation, identification and sequence analysis of a thioredoxin h gene, a member of subgroup iii of h-type trxs from grape (vitis vinifera l. cv. askari). | thioredoxins (trxs) are small ubiquitous proteins which play a regulatory role in a variety of cellular processes. in contrast to other organisms, plants have a great number of trx types, consisting of six well-defined groups: f, m, x, and y in chloroplasts, o in mitochondria, and h mainly in cytosol. a full-length cdna, designated vvcxxs2, encoding trx h polypeptide was isolated and cloned from grape (vitis vinifera l. cv. askari) berries organ by reverse transcription polymerase chain reaction ... | 2011 | 21732058 |
| suppression of stat3 and hif-1 alpha mediates anti-angiogenic activity of betulinic acid in hypoxic pc-3 prostate cancer cells. | signal transducer and activator of transcription 3 (stat3) is a transcription factor that regulates various cellular processes such as cell survival, angiogenesis and proliferation. in the present study, we examined that betulinic acid (ba), a triterpene from the bark of white birch, had the inhibitory effects on hypoxia-mediated activation of stat3 in androgen independent human prostate cancer pc-3 cells. | 2011 | 21731766 |
| the effect of nutrient stress on developmental instability in leaves of acer platanoides (aceraceae) and betula pendula (betulaceae). | studies of developmental stability can provide insights into the amount of genetic or environmental stress experienced by individuals or populations. in the present study, we used young plants of acer platanoides (norway maple) and betula pendula (silver birch), two distantly related tree species with widely different leaf morphologies, to compare the expression of developmental instability in two contrasting environments: one with free access to nutrients and the other with a severely limited s ... | 2003 | 21659210 |
| Liberomyces gen. nov. with two new species of endophytic coelomycetes from broad-leaved trees. | During a study of endophytic and saprotrophic fungi in the sapwood and phloem of broad-leaved trees (Salix alba, Quercus robur, Ulmus laevis, Alnus glutinosa, Betula pendula), fungi belonging to an anamorphic coelomycetous genus not attributable to a described taxon were detected and isolated in pure culture. The new genus Liberomyces with two species, L. saliciphilus and L. macrosporus, is described. Both species have subglobose conidiomata containing holoblastic sympodial conidiogenous cells. ... | 2011 | 21937729 |
| N(2) fixation and cycling in Alnus glutinosa, Betula pendula and Fagus sylvatica woodland exposed to free air CO(2) enrichment. | We measured the effect of elevated atmospheric CO(2) on atmospheric nitrogen (N(2)) fixation in the tree species Alnus glutinosa growing in monoculture or in mixture with the non-N(2)-fixing tree species Betula pendula and Fagus sylvatica. We addressed the hypotheses that (1) N(2) fixation in A. glutinosa will increase in response to increased atmospheric CO(2) concentrations, when growing in monoculture, (2) the impact of elevated CO(2) on N(2) fixation in A. glutinosa is the same in mixture an ... | 2011 | 22179329 |
| boron nutrition affects the carbon metabolism of silver birch seedlings. | boron (b) is an essential micronutrient whose deficiency is common both in agriculture and in silviculture. boron deficiency impairs the growth of plants and affects many metabolic processes like carbohydrate metabolism. boron deficiency and also excess b may decrease the sink demand by decreasing the growth and sugar transport which may lead to the accumulation of carbohydrates and down-regulation of photosynthesis. in this study, we investigated the effects of b nutrition on the soluble and st ... | 2011 | 22084021 |
| temporal variation in epidermal flavonoids due to altered solar uv radiation is moderated by the leaf position in betula pendula. | the physiological mechanisms controlling plant responses to dynamic changes in ambient solar ultraviolet (uv) radiation are not fully understood: this information is important to further comprehend plant adaptation to their natural habitats. we used the fluorimeter dualex to estimate in vivo the epidermal flavonoid contents by measuring epidermal uv absorbance (a(375) ) in betula pendula roth (silver birch) leaves of different ages under altered uv. seedlings were grown in a greenhouse for 15 da ... | 2011 | 21883252 |
| [karelian birch (betula pendula roth. var. carelica merkl.) as a model for studying genetic and epigenetic variation related to the formation of patterned wood]. | the results of long-term pioneering studies on in vitro micropropagation of karelian birch patterned forms and simultaneous cytological analysis of plants multiplied using different periods of in vitro culturing are published for the first time. the patterned wood character has been shown to be correlated with the degree of mixoploidy of its somatic tissue, which is higher in the plants obtained from callus cultures during the first years of culturing. subsequent intracellular selection leads to ... | 2011 | 21954616 |
| inter- and intra-specific variation in stem phloem phenolics of paper birch (betula papyrifera) and european white birch (betula pendula). | outbreaks of bronze birch borer (bbb) (agrilus anxius), a wood-boring beetle endemic to north america, have been associated with widespread mortality of birch (betula spp.). there is substantial inter- and intra-specific variation in birch resistance to bbb. species endemic to north america, such as paper birch (b. papyrifera), have coevolved with bbb and are more resistant than european and asian birch species, such as european white birch (b. pendula), which lack an evolutionary history with b ... | 2011 | 22012323 |
| vertical profiles reveal impact of ozone and temperature on carbon assimilation of betula pendula and populus tremula. | rising temperature and tropospheric ozone (o(3)) concentrations are likely to affect carbon assimilation processes and thus the carbon sink strength of trees. in this study, we investigated the joint action of elevated ozone and temperature on silver birch (betula pendula) and european aspen (populus tremula) saplings in field conditions by combining free-air ozone exposure (1.2 × ambient) and infrared heaters (ambient +1.2 °c). at leaf level measurements, elevated ozone decreased leaf ne ... | 2011 | 21856655 |
| interspecific variation in resistance of asian, european, and north american birches (betula spp.) to bronze birch borer (coleoptera: buprestidae). | bronze birch borer (agrilus anxius gory) is the key pest of birches (betula spp.) in north america, several of which have been recommended for ornamental landscapes based on anecdotal reports of borer resistance that had not been confirmed experimentally. in a 20-yr common garden experiment initiated in 1979 in ohio, north american birch species, including paper birch (betula papyrifera marshall), 'whitespire' gray birch (betula populifolia marshall), and river birch (betula nigra l.), were muc ... | 2011 | 22251643 |
| procyanidin xylosides from the bark of betula pendula. | a procyanidin dimer xyloside, catechin-(4α→8)-7-o-β-xylopyranosyl-catechin, was isolated from the inner bark of betula pendula and its structure was determined using 1d and 2d nmr, cd and high-resolution esims. interestingly, the 7-o-β-xylopyranose unit was found to be present in the lower terminal unit of the dimer. in addition to this procyanidin dimer xyloside, an entire series of oligomeric and polymeric procyanidin xylosides was detected. their structures were investigated by hydrophilic in ... | 2012 | 22273040 |
| species-specific effect of uv-b radiation on the temporal pattern of leaf growth. | recent molecular and physiological studies have demonstrated that ultraviolet-b radiation (uv-b) can affect some of the processes involved in leaf growth, but the phases of leaf growth affected have not been clearly delimited. we used functional growth analysis to assess the effects of uv-b radiation on the time course of leaf growth in seedlings of two birch species (betula pendula and betula pubescens). our aim was to identify the phase(s) of leaf development affected by uv-b radiation. in a g ... | 2012 | 22224454 |
| [the influence of the triterpenoid from the weeping birch (betula pendula) on the changed reactivity of an organism exposed to action of the dust-radiating factor]. | the obtained data testify about immunmodulating properties of the given medicine. influence of "be phytomedicine on organism, which undergoes dust-radiation factor leads to positive dynamics in humoral and cellular parts of immunity, also to increasing immunological reactivity of an organism. | 2011 | 22279741 |
| host species and strain combination determine growth reduction of spruce and birch seedlings colonized by root-associated dark septate endophytes. | interactions of betula pendula and picea abies with dark septate endophytes of the phialocephala fortinii-acephala applanata species complex (pac) were studied. pac are ubiquitous fungal root symbionts of many woody plant species but their ecological role is largely unknown. sterile birch and spruce seedlings in monoculture and mixed culture were exposed to four pac strains, added either singularly or paired in all possible combinations at 18°c and 23°c. plant and fungal biomass was determined a ... | 2011 | 22212126 |
| survey of microfungi in the landschaftspark duisburg-nord (germany). | during an excursion in the landschaftspark duisburg-nord in 2009 and 2010 we were able to collect and identify more than 100 specimens of microfungi on different parts of cultivated and wild plant species. we found parasitic and saprophytic microfungi on trees, bushes and herbaceous plants. some of them have been observed only rarely until now. most of the collected microfungi species belong to the classes of ascomycetes, basidiomycetes and deuteromycetes - for example leptosphaeria modesta (des ... | 2011 | 22702187 |
| tree species diversity interacts with elevated co2 to induce a greater root system response. | as a consequence of land-use change and the burning of fossil fuels, atmospheric concentrations of co2 are increasing and altering the dynamics of the carbon cycle in forest ecosystems. in a number of studies using single tree species, fine root biomass has been shown to be strongly increased by elevated co2 . however, natural forests are often intimate mixtures of a number of co-occurring species. to investigate the interaction between tree mixture and elevated co2 , alnus glutinosa, betula pen ... | 2012 | 23504733 |
| nutrient supply has greater influence than sink strength on photosynthetic adaptation to co2 elevation in white birch seedlings. | to study the effects of source-sink ratio and nutrient supply on photosynthetic acclimation to co(2) elevation, we subjected white birch seedlings to two levels of nutrient supply (high vs. low) and co(2) concentrations (ambient vs. doubled [co(2)]) for two months and then shaded the lower canopy on half of the seedlings to reduce source/sink ratio for an additional month. the co(2) elevation significantly increased p(n) and iwue at both nutrient levels but the increase was greater in the high t ... | 2012 | 23415328 |
| pollen-associated microbiome correlates with pollution parameters and the allergenicity of pollen. | pollen allergies have been rapidly increasing over the last decades. many allergenic proteins and non-allergenic adjuvant compounds of pollen are involved in the plant defense against environmental or microbial stress. the first aim of this study was to analyze and compare the colonizing microbes on allergenic pollen. the second aim was to investigate detectable correlations between pollen microbiota and parameters of air pollution or pollen allergenicity. to reach these aims, bacterial and fung ... | 2016 | 26910418 |
| antimicrobial activity of natural products from the flora of northern ontario, canada. | the number of multidrug resistant (mdr) microorganisms is increasing and the antimicrobial resistance expressed by these pathogens is generating a rising global health crisis. in fact, there are only a few antimicrobial agents left that can be used against mdr bacteria and fungi. | 2015 | 25697605 |
| medicinal plant extracts can variously modify biofilm formation in escherichia coli. | low concentrations of black tea and water extracts from medicinal plants arctostaphylos uva-ursi, vaccinium vitis-idaea, tilia cordata, betula pendula and zea mays stimulated biofilm formation in escherichia coli bw25113 up to three times. similar effect was observed for tannic acid and low concentrations of quercetin. in contrast, the extract from urtica dioica reduced biofilm production. pretreatment with plant extracts variously modified antibiotic effects on specific biofilm formation (sbf). ... | 2014 | 24500005 |
| medicinal plants extracts affect virulence factors expression and biofilm formation by the uropathogenic escherichia coli. | medicinal plants are an important source for the therapeutic remedies of various diseases including urinary tract infections. this prompted us to perform research in this area. we decided to focus on medicinal plants species used in urinary tract infections prevention. the aim of our study was to determine the influence of betula pendula, equisetum arvense, herniaria glabra, galium odoratum, urtica dioica, and vaccinium vitis-idaea extracts on bacterial survival and virulence factors involved in ... | 2012 | 22915095 |
| [report of quambalaria cyanescens associated with birch]. | long-term microbiological investigation of the pollen of silver birch (betula pendula) in the mos- cow, and moscow region areas revealed that: almost one-third of the analyzed samples, contained the fungus identified by morphological, cultural, and molecular genetic techniques as quambalaria cyanescens (de hoog & g. a. de vries) z.w. de beer, begerow & r. bauer. this species was previously known mostly as a syrmbiont of tropical plants of the generaeucalyptus and cortyminbia and has not been iso ... | 2015 | 25844472 |
| bioconversion of birch wood hemicellulose hydrolyzate to xylitol. | a sugar solution containing 42.9 g l(-1) of xylose was prepared from the wood of japanese white birch (betula platyphylla var. japonica) by hydrolysis with 3 % sulfuric acid with a liquor-to-solid ratio of 4 (g g(-1)) at 120 °c for 1 h. during the acid hydrolysis, undesirable by-products were generated, such as acetic acid, furfural, and low-molecular-weight phenols, which inhibit bioconversion of xylose to xylitol. these inhibitors were successfully removed from the hydrolyzate by sorption onto ... | 2015 | 25894947 |
| combining microtomy and confocal laser scanning microscopy for structural analyses of plant-fungus associations. | the serious problem of extended tissue thickness in the analysis of plant-fungus associations was overcome using a new method that combines physical and optical sectioning of the resin-embedded sample by microtomy and confocal microscopy. improved tissue infiltration of the fungal-specific, high molecular weight fluorescent probe wheat germ agglutinin conjugated to alexa fluor® 633 resulted in high fungus-specific fluorescence even in deeper tissue sections. if autofluorescence was insufficient, ... | 2014 | 24249491 |
| incorporating interspecific competition into species-distribution mapping by upward scaling of small-scale model projections to the landscape. | there are a number of overarching questions and debate in the scientific community concerning the importance of biotic interactions in species distribution models at large spatial scales. in this paper, we present a framework for revising the potential distribution of tree species native to the western ecoregion of nova scotia, canada, by integrating the long-term effects of interspecific competition into an existing abiotic-factor-based definition of potential species distribution (psd). the ps ... | 2017 | 28207782 |
| influence of partial cutting on parasitism of endemic spruce budworm (lepidoptera: tortricidae) populations. | silvicultural treatments such as thinning have been suggested as management tools against the spruce budworm, choristoneura fumiferana (clemens) (lepidoptera: tortricidae). among other things, parasitoids are also proposed to be influenced by silvicultural procedures, but the effect of thinning on spruce budworm's natural enemies has not been tested yet. in this study, the influence of partial cutting on parasitism of endemic spruce budworm populations has been investigated in mature balsam fir- ... | 2014 | 24780195 |
| levels of selected trace elements in scots pine (pinus sylvestris l.), silver birch (betula pendula l.), and norway maple (acer platanoides l.) in an urbanized environment. | the aim of the study was to determine the concentrations of selected trace elements in needles and bark of scots pine (pinus sylvestris l.), leaves and bark of silver birch (betula pendula l.), and norway maple (acer platanoides l.), as well as in the soil in which the trees grew, depending on their localization and hence the distribution of local pollution sources. the content of trace elements in needles of scots pine, leaves of silver birch, and norway maple and in bark of these trees depende ... | 2016 | 27696092 |
| the role of selected tree species in industrial sewage sludge/flotation tailing management. | the aim of the study was to estimate the ability of ten tree and bush species to tolerate and accumulate cd, cu, pb, zn, and as species [as(iii), as(v), and total organic arsenic] in industrial sewage sludge extremely contaminated with arsenic (almost 27.5 g kg(-1)) in a pot experiment. the premise being that it will then be possible to select the most promising tree/bush species, able to grow in the vicinity of dams where sewage sludge/flotation tailings are used as landfill. six of the ten tes ... | 2016 | 27348264 |
| chemometrics in biomonitoring: distribution and correlation of trace elements in tree leaves. | the concentrations of 15 elements were measured in the leaf samples of aesculus hippocastanum, tilia spp., betula pendula and acer platanoides collected in may and september of 2014 from four different locations in belgrade, serbia. the objective was to assess the chemical characterization of leaf surface and in-wax fractions, as well as the leaf tissue element content, by analyzing untreated, washed with water and washed with chloroform leaf samples, respectively. the combined approach of self- ... | 2016 | 26748000 |
| evaluation of urban environment pollution based on the accumulation of macro- and trace elements in epiphytic lichens. | nitrogen, phosphorus, potassium, magnesium, zinc, nickel, copper, manganese, iron and lead accumulation properties of three epiphytic lichen species (hypogymnia physodes (l.) nyl., parmelia sulcata taylor and xanthoria parietina (l.) th. fr.) were compared. an assessment of pollution of the municipal environment in słupsk (poland) according to macro- and trace elements was also done. lichen samples were taken in autumn 2013 from betula pendula, fraxinus excelsior, acer platanoides, a. pseudoplat ... | 2016 | 26745547 |
| transpiration of urban trees and its cooling effect in a high latitude city. | an important ecosystem service provided by urban trees is the cooling effect caused by their transpiration. the aim of this study was to quantify the magnitude of daytime and night-time transpiration of common urban tree species in a high latitude city (gothenburg, sweden), to analyse the influence of weather conditions and surface permeability on the tree transpiration, and to find out whether tree transpiration contributed to daytime or nocturnal cooling. stomatal conductance and leaf transpir ... | 2016 | 26048702 |
| tree species composition affects the abundance of rowan (sorbus aucuparia l.) in urban forests in finland. | recent studies have shown a considerable increase in the abundance of rowan (sorbus aucuparia) saplings in urban forests in finland, yet the reasons for this increase are not well understood. here we investigated whether canopy cover or tree species composition, i.e., the basal areas of different tree species in norway spruce dominated urban forests, affects the abundances of rowan seedlings, saplings and trees. altogether 24 urban forest patches were investigated. we sampled the number of rowan ... | 2015 | 25588119 |
| plant species differences in particulate matter accumulation on leaf surfaces. | particulate matter (pm) accumulation on leaves of 22 trees and 25 shrubs was examined in test fields in norway and poland. leaf pm in different particle size fractions (pm(10), pm(2.5), pm(0.2)) differed among the species, by 10- to 15-folds at both test sites. pinus mugo and pinus sylvestris, taxus media and taxus baccata, stephanandra incisa and betula pendula were efficient species in capturing pm. less efficient species were acer platanoides, prunus avium and tilia cordata. differences among ... | 2012 | 22554531 |
| metal resistance in populations of red maple (acer rubrum l.) and white birch (betula papyrifera marsh.) from a metal-contaminated region and neighbouring non-contaminated regions. | metal resistance in populations of acer rubrum and betula papyrifera in the industrially contaminated region of sudbury, ontario, was compared with resistance in populations from neighbouring uncontaminated regions. in two one-season experiments, seedlings were grown outdoors on contaminated (mainly cu, ni) and uncontaminated substrates. sudbury populations of both species responded less to contamination than populations from uncontaminated regions. in a. rubrum this difference was small. for bo ... | 2012 | 22336730 |
| selective behaviour of honeybees in acquiring european propolis plant precursors. | honey bees harvest resins from various plant species and use them in the hive as propolis. while there have been a number of studies concerning the chemical composition of this antimicrobial product, little is known about selective behavior and bee preference when different potential plant sources of resin are available. the main objective of this paper was to investigate some aspects of behavioral patterns of honeybees in the context of resin acquisition. samples of propolis originating from te ... | 2016 | 27294416 |
| suitability of different pollen as alternative food for the predatory mite amblyseius swirskii (acari, phytoseiidae). | the predacious mite amblyseius swirskii athias-henriot is used as a biological control agent against various pests in greenhouses. pollen offered as supplementary food is reported to improve their fast establishment and performance. however, the nutritional suitability of different pollens for a. swirskii is not sufficiently known yet. pollens of 21 plant species were offered to the mites as exclusive food during preimaginal development. preimaginal mortality and developmental time have been ass ... | 2013 | 23670826 |
| two new species of oobius trjapitzin (hymenoptera, encyrtidae) egg parasitoids of agrilus spp. (coleoptera, buprestidae) from the usa, including a key and taxonomic notes on other congeneric nearctic taxa. | oobius trjapitzin (hymenoptera, encyrtidae) species are egg parasitoids that are important for the biological control of some buprestidae and cerambycidae (coleoptera). two species, oobiusagrili zhang & huang and oobiuslongoi (siscaro), were introduced into north america for classical biocontrol and have successfully established. two new native north american species that parasitize eggs of agrilus spp. (buprestidae) are described and illustrated from the usa: oobiusminusculus triapitsyn & petri ... | 2015 | 25931963 |
| long-term changes of metal contents in two metallophyte species (olkusz area of zn-pb ores, poland). | the authors present the changes of the as, cd, fe, mn, pb and zn contents in two plant-considered metallophytes: common bent agrostis capillaris (blades) and birch betula pendula (leaves and seeds), recorded in a zn-pb industrial region of olkusz (poland) in 1994 and 2014. the highest amounts of cd (12 ppm) and zn (2524 ppm) in the common bent occur in the vicinity of the mining and metallurgical works 'bolesław' in bukowno. however, these values are significantly lower than those in 1994: cd by ... | 2016 | 27165603 |
| effects of tree species richness and composition on moose winter browsing damage and foraging selectivity: an experimental study. | the optimal foraging theory, the nutrient balance hypothesis, and the plant association theories predict that foraging decisions and resulting tree damage by large mammalian browsers may be influenced by the species richness and species composition of forest stands. this may lead to either associational susceptibility (increased damage on a focal plant in a mixed stand) or associational resistance (reduced damage in a mixed stand). better understanding of the mechanisms and the relative importan ... | 2013 | 23363076 |
| synthesis of siderophores by plant-associated metallotolerant bacteria under exposure to cd(2.). | rhizosphere and endophytic bacteria are well known producers of siderophores, organic compounds that chelate ferric iron (fe(3+)), and therefore play an important role in plant growth promotion in metalliferous areas, thereby improving bioremediation processes. however, in addition to their primary function in iron mobilization, siderophores also have the capacity to chelate other heavy metals, such as al(3+), zn(2+), cu(2+), pb(2+) and cd(2+), that can affect homeostasis and the heavy metal tol ... | 2016 | 27183333 |