Publications
| Title | Abstract | Year(sorted descending) Filter | PMID Filter |
|---|
| betulinic acid suppresses carcinogen-induced nf-kappa b activation through inhibition of i kappa b alpha kinase and p65 phosphorylation: abrogation of cyclooxygenase-2 and matrix metalloprotease-9. | betulinic acid (ba), a pentacyclic triterpene isolated from the bark of the white birch tree, has been reported to be a selective inducer of apoptosis in tumor cells. it also exhibits anti-inflammatory and immunomodulatory properties. how ba mediates these effects is not known. because of the critical role of the transcription factor nf-kappab in growth modulatory, inflammatory, and immune responses, we postulated that ba modulates the activity of this factor. in this study we investigated the e ... | 2003 | 12960358 |
| postglacial recolonization and cpdna variation of silver birch, betula pendula. | chloroplast pcr-rflp markers were used to reconstruct the history of the silver birch, betula pendula roth, in europe since the last glacial maximum (lgm). in birch, fossil pollen maps do not reveal a clear chronological sequence of postglacial spread. if anything, the pollen record suggests that most of europe was recolonized by birches as early as 10000 bp, probably from populations that remained close to the ice sheets during the lgm. the geographical distribution of haplotypes supports a sce ... | 2003 | 12492888 |
| biochemical acclimation patterns of betula pendula and pinus sylvestris seedlings to elevated carbon dioxide concentrations. | acclimation of photosynthesis to increasing atmospheric carbon dioxide concentration ([co2]; 350 to 2,000 micromol mol-1) was followed in silver birch (betula pendula roth.) and scots pine (pinus sylvestris l.) seedlings for two years. chlorophyll fluorescence and concentrations of rubisco, chlorophyll, total soluble protein and nitrogen were monitored together with steady-state gas exchange at three co2 concentrations (ambient [co2] (345 +/- 20 micromol mol-1), the growth [co2] and 1950 +/- 55 ... | 2003 | 12533303 |
| dna sequence variation in bpmads2 gene in two populations of betula pendula. | the pistillata (pi) homologue, bpmads2, was isolated from silver birch (betula pendula roth) and used to study nucleotide polymorphism. two regions (together about 2450 bp) comprising mainly untranslated sequences were sequenced from 10 individuals from each of two populations in finland. the nucleotide polymorphism was low in the bpmads2 locus, especially in the coding region. the synonymous site overall nucleotide diversity (pis) was 0.0043 and the nonsynonymous nucleotide diversity (pia) was ... | 2003 | 12535088 |
| adaptive significance of c partitioning and regulation of specific leaf area in betula pendula. | carbon allocation and regulation of specific leaf area (sigma) define key processes underlying the adaptation of plants to varying habitats. in this study, the general principles governing adaptation and a dynamic optimality model of plant adaptation are reviewed. the central new elements of this model are: (i) differential root carbon costs for maintaining a defined nutrient status; (ii) a simple formula for optimal sigma at steady-state as a function of nitrogen (n) status and irradiance; and ... | 2003 | 12566268 |
| deciphering the 820 nm signal: redox state of donor side and quantum yield of photosystem i in leaves. | by recording leaf transmittance at 820 nm and quantifying the photon flux density of far red light (frl) absorbed by long-wavelength chlorophylls of photosystem i (ps i), the oxidation kinetics of electron carriers on the ps i donor side was mathematically analyzed in sunflower (helianthus annuus l.), tobacco (nicotiana tabacum l.) and birch (betula pendula roth.) leaves. ps i donor side carriers were first oxidized under frl, electrons were then allowed to accumulate on the ps i donor side duri ... | 2003 | 16245060 |
| 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 |
| genotype-environment interactions in pollen competitive ability in an anemophilous tree, betula pendula roth. | this study describes genotype-environment interactions in pollen competitive ability expressed as pollen-tube growth rate and seed-siring success in betula pendula roth. a factorial crossing design was applied using the same maternal and paternal clones in two different environmental conditions, in a b. pendula seed orchard established in a greenhouse and at an outdoor clone collection. both single donor and two-donor pollinations were employed. female inflorescences were collected after a fixed ... | 2002 | 12582552 |
| distribution of hydrolysable tannins in the foliage of finnish birch species. | on the basis of qualitative and quantitative analysis with liquid chromatography--electrospray ionisation mass spectrometry, the foliage of dwarf birch (betula nana l.), silver birch (b. pendula roth) and mountain birch (b. pubescens ssp. czerepanovii (orlova) hämet-ahti) were found, for the first time, to contain the same individual hts that were described earlier for white birch (b. pubescens ehrh.). in addition, one previously unidentified ellagitannin was preliminarily identified from the le ... | 2002 | 12064722 |
| mercury levels in lichens from different host trees around a chlor-alkali plant in new brunswick, canada. | mercury concentrations were determined in the epiphytic lichen hypogymnia physodes along five transects starting from a chlor-alkali plant located at dalhousie, new brunswick, a landfill site and a nearby electricity generating station. lichen samples were collected from white birch (betula papyrifera) and spruce (picea sp.) or balsam fir (abies balsamea). average lichen background mercury values were 0.088+/-0.005 microg/g from white birch and 0.148+/-0.046 microg/g from spruce trees, with a de ... | 2002 | 12109479 |
| hydrogen peroxide activates cell death and defense gene expression in birch. | the function of hydrogen peroxide (h(2)o(2)) as a signal molecule regulating gene expression and cell death induced by external stresses was studied in birch (betula pendula). ozone (o(3)), pseudomonas syringae pv syringae (pss), and wounding all induced cell death of various extents in birch leaves. this was temporally preceded and closely accompanied by h(2)o(2) accumulation at, and especially surrounding, the lesion sites. o(3) and pss, along with an artificial h(2)o(2) producing system gluco ... | 2002 | 12376624 |
| nitrate reductase activity in some subarctic species and uv influence in the foliage of betula pendula roth. seedlings. | nitrate reductase (nr) activity was studied in the foliage of five subarctic species: mature trees of european white birch (betula pubescens erch. s.s.), scots pine (pinus sylvestris l.), norway spruce (picea abies l. karst), ericaceous shrub bilberry (vaccinium myrtillus l.), naturally growing in a forest, and seed-grown silver birch (betula pendula roth.) seedlings in an ultraviolet (uv) exclusion field experiment at the pallas-ounastunturi national park in finnish lapland (68 degrees n). mean ... | 2002 | 11846159 |
| microbial transformations of two lupane-type triterpenes and anti-tumor-promoting effects of the transformation products. | microbial transformation of betulin (1), a lupane-type triterpene obtained from the bark extract of white birch (betula platyphylla sukatshev var. japonica), and its chemical oxidation product, betulonic acid (2), by the fungus chaetomium longirostre yielded 4,28-dihydroxy-3,4-seco-lup-20(29)-en-3-oic acid (3) and 4-hydroxy-3,4-seco-lup-20(29)-ene-3,28-dioic acid (4) from 1, and 4,7beta,17-trihydroxy-3,4-seco-28-norlup-20(29)-en-3-oic acid (5) and 7 beta,15 alpha-dihydoxy-3-oxolup-20(29)-en-28-o ... | 2002 | 11908965 |
| the impact of wood ice cream sticks' origin on the aroma of exposed ice cream mixes. | the effect of volatile compounds in white birch sticks obtained from four different geographical locations on the aroma of ice cream mix was investigated. sensory evaluation, (specifically, a series of warmed-up paired comparisons) was conducted on stick-exposed ice cream mixes to determine whether aroma differences in those mixes could be detected. batches of ice cream mix were exposed to the sticks and aged for 6 d at 4 degrees c and then assessed by the panelists by pairwise comparison. findi ... | 2002 | 11913694 |
| the major birch allergen, bet v 1, shows affinity for a broad spectrum of physiological ligands. | bet v 1 is a 17-kda protein abundantly present in the pollen of the white birch tree and is the primary cause of birch pollen allergy in humans. its three-dimensional structure is remarkable in that a solvent-accessible cavity traverses the core of the molecule. the biological function of bet v 1 is unknown, although it is homologous to a family of pathogenesis-related proteins in plants. in this study we first show that bet v 1 in the native state is able to bind the fluorescent probe 8-anilino ... | 2002 | 11953433 |
| foliar phenolic composition of european white birch during bud unfolding and leaf development. | we studied the between-tree and within-tree variation in the composition and content of foliar low-molecular-weight phenolics (lmwp) of european white birch (betula pendula roth) during the unfolding of vegetative buds and during early leaf development. in buds, the major groups of phenolic compounds were hydrolysable tannins and flavonoid aglycones, whereas, later during leaf development, the flavonoid glycosides accounted for most of the total lmwp. the content of total lmwp, as well as indivi ... | 2002 | 12060268 |
| effects of long-term, elevated ultraviolet-b radiation on phytochemicals in the bark of silver birch (betula pendula). | long-term outdoor experiments were conducted to investigate the effects of elevated ultraviolet-b (uv-b, 280-320 nm) radiation on secondary metabolites (phenolics and terpenoids) and the main soluble sugars (sucrose, raffinose and glucose) in the bark of silver birch (betula pendula roth) saplings. saplings were exposed to a constant 50% increase in erythemal uv irradiance (uv-b(cie); based on the cie (international commission on illumination) erythemal action spectrum) and a small increase in u ... | 2002 | 12464579 |
| leaching of nitrogen and phosphorus during production of forest seedlings in containers. | little information is available concerning the contamination risk caused by forest seedling nurseries to local surface and ground waters compared with agricultural and horticultural production. leaching of nitrogen (n) and phosphorus (p) through peat growing medium in containers and nutrient uptake of seedlings were monitored in production of silver birch (betula pendula roth), norway spruce [picea abies (l.) karst], and scots pine (pinus sylvestris l.) seedlings. about half of the applied nutri ... | 2002 | 12469836 |
| the inhibition of ammonium uptake in excised birch (betula pendula) roots by batatasin-iii. | in northern sweden, plants growing in association with the clonal dwarf shrub empetrum hermaphroditum usually exhibit limited growth and are n-depleted. previous studies suggest that this negative effect by e. hermaphroditum may be explained, at least in part, by the release of phenolic compounds, particularly the dihydrostilbene, batatasin-iii from foliage to soil. in the present work, we investigated whether batatasin-iii has the potential to interfere with nh4+ uptake in birch (betula pendula ... | 2001 | 12060282 |
| ascorbate transport from the apoplast to the symplast in intact leaves. | infiltration of reduced ascorbate (asc) into the leaves of betula pendula roth and subsequent measurement of its loss therein after incubation allowed us to follow ascorbate transport from apoplast to symplast in intact leaves. all of the ascorbate extracted from the native apoplast was in fully oxidized form, dehydroascorbate (dha). when 5 mm of asc was infiltrated into the leaves, its intense decay occurred, but only 55% of asc lost was recovered in apoplast as dha. when asc was added to the f ... | 2001 | 12060283 |
| clonal differences in copper and zinc tolerance of birch in metal-supplemented soils. | metal tolerance of a range of birch clones (betula pendula and betula pubescens) originating from metal-contaminated sites in england, wales, belgium and finland were tested in soils supplemented with several concentrations of copper (cu) or zinc (zn) (500, 2000, 5000 mg kg-1 dry wt. soil of cuso(4).5h2o or znso(4).7h2o) for 4 months and with sub-toxic metal supplements (500 mg cuso4, 2000 mg znso4) for 6 months. when grown at high concentrations of metals, severe toxicity symptoms (growth inhib ... | 2001 | 11202657 |
| manganese toxicity as indicated by visible foliar symptoms of japanese white birch (betula platyphylla var. japonica). | for the purpose of a field diagnosis of mn toxicity, we showed the possibility of using visible foliar symptoms of japanese white birch (betula platyphylla var. japonica hara) as indicator. to examine the relationship between the expression of visible symptoms and leaf mn concentrations, white birch seedlings were grown under four different mn levels: 1 mg mn l-1 as control, 10, 50 and 100 mg mn l-1. foliar symptoms of mn toxicity for white birch were: (1) chlorosis at entire young leaves in the ... | 2001 | 11202719 |
| ozone exposure thresholds and foliar injury on forest plants in switzerland. | canton ticino in southern switzerland is exposed to some of the highest concentrations of tropospheric ozone in europe. during recent field surveys in canton ticino, foliar symptoms identical to those caused by ozone have been documented on native tree and shrub species. in europe, the critical ozone level for forest trees has been defined at an aot40 of 10 ppm.h o3 (10 ppm.h accumulated exposure of ozone over a threshold of 40 ppb) during daylight hours over a six-month growing season. the obje ... | 2001 | 11202736 |
| temperature response of leaf photosynthetic capacity in seedlings from seven temperate tree species. | seedlings of seven temperate tree species (acer pseudoplatanus l., betula pendula roth, fagus sylvatica l., fraxinus excelsior l., juglans regia l., quercus petraea matt. liebl. and quercus robur l.) were grown in a nursery under neutral filters transmitting 45% of incident global irradiance. during the second or third year of growth, leaf photosynthetic capacity (i.e., maximal carboxylation rate, vcmax, maximal photosynthetic electron transport rate, jmax, and dark respiration, rd) was estimate ... | 2001 | 11276416 |
| three mads-box genes similar to apetala1 and fruitfull from silver birch (betula pendula). | despite intensive research on genetic regulation of flower development there are still only a few studies on the early phases of this process in perennial plants like trees. the aim of this study has been to identify genes that regulate early stages of inflorescence development in silver birch (betula pendula roth) and to follow the expression of these genes during development of the unisexual birch inflorescences. here we describe the cloning and characterization of 3 cdnas representing mads-bo ... | 2001 | 11319020 |
| seasonal variation in the content of hydrolysable tannins in leaves of betula pubescens. | the contents of 13 hydrolysable tannins in the leaves of white birch (betula pubescens l.) trees were analysed at twelve stages throughout the growing season. all individual galloylglucoses, from 1-o-galloyl-beta-d-glucopyranose to 1,2,3,4,6-penta-o-galloyl-beta-d-glucopyranose, accumulated in young leaves, while ellagitannins showed significantly variable seasonal trends. the major ellagitannin during the whole growing season was pedunculagin while 2,3-(s)-hhdp-glucopyranose. the end product of ... | 2001 | 11336256 |
| do pollen donors with fastest-growing pollen tubes sire the best offspring in an anemophilous tree, betula pendula (betulaceae)? | the relationship between pollen and progeny performance has been a subject of many studies but the evidence for pollen-tube growth rate as an indicator of progeny fitness is equivocal. we used an anemophilous tree, betula pendula, to examine the relationship between pollen-tube growth rate and seed and seedling performance. we crossed nine maternal plants with pollen from six pollen donors in a clonal b. pendula seed orchard, measured the pollen-tube growth rates for every cross, and analyzed th ... | 2001 | 11353710 |
| variation of gas exchange within native plant species of switzerland and relationships with ozone injury: an open-top experiment. | gas exchange and ozone-induced foliar injury were intensively measured during a 6-day period in mid-august 1998 on leaves of acer pseudoplatanus, betula pendula, corylus avellana, fagus sylvatica, fraxinus excelsior, morus nigra, prunus avium, prunus serotina, rhamnus cathartica, and viburnum lantana at a forest nursery site in canton ticino, switzerland. plants were grown in four open plots (aa), four open-top chambers receiving carbon-filtered (cf) air, and four receiving non-filtered (nf) air ... | 2001 | 11383335 |
| why plants grow poorly on very acid soils: are ecologists missing the obvious? | factors associated with soil acidity are considered to be limiting for plants in many parts of the world. this work was undertaken to investigate the role of the toxicity of hydrogen (h(+)) which seems to have been underconsidered by ecologists as an explanation of the reduced plant growth observed in very acid soils. racial differences are reported in plant growth response to increasing acidity in the grass holcus lanatus l. (yorkshire-fog) and the tree betula pendula roth (silver birch). soils ... | 2001 | 11413215 |
| exploitation of pollen by mycorrhizal mycelial systems with special reference to nutrient recycling in boreal forests. | very large quantities of pollen are released annually by wind-pollinated trees, which dominate northern forest ecosystems. since pollen is enriched in both nitrogen and phosphorus, this recurrent pulse of deposition constitutes a significant potential source of these elements in what are known to be severely nutrient-limited systems. here, we demonstrate for the first time, to our knowledge, that an ectomycorrhizal fungus, paxillus involutus, is able to scavenge effectively for nitrogen and phos ... | 2001 | 11429131 |
| [the pollen survey and dynamic statistics of patients with allergic rhinitis in hakodate]. | we have investigated the pollen survey (1994-1998) and dynamic statistics of patients with allergic rhinitis (1999-2000) in hakodate, which is located southern part of hokkaido. we have noted the pollen dispersion of cryptomeria japonica, cupressaceae, white birch, gramineae and artemisia. especially, a lot of dispersion of cryptomeria japonica has been noted in april. concerning the dynamic statistics of patients with allergic rhinitis, we have investigated the 192 patients with allergic rhinit ... | 2001 | 11436334 |
| free radical scavenging activities measured by electron spin resonance spectroscopy and b16 cell antiproliferative behaviors of seven plants. | in an effort to discover new antioxidant natural compounds, seven plants that grow in france (most of them in the limousin countryside) were screened. among these plants, was the extensively studied vitis vinifera as reference. for each plant, sequential percolation was realized with five solvents of increasing polarities (hexane, chloroform, ethyl acetate, methanol, and water). free radical scavenging activities were examined in different systems using electron spin resonance (esr) spectroscopy ... | 2001 | 11453770 |
| effects of long-term open-field ozone exposure on leaf phenolics of european silver birch (betula pendula roth). | the response of phenolic compounds as a result of long-term low open-field ozone exposure was studied in ozone-sensitive and ozone-tolerant clones of european silver birch (betula pendula roth). the saplings were exposed to 1.5-1.6 times the ambient (elevated) ozone and ambient air (as control) over three growing seasons from may 1996 until august 1998. quantification by modified folin-ciocalteau assay showed a 16.2% increase in total phenolics in elevated ozone plants as compared to that in con ... | 2001 | 11471939 |
| phosphoenolpyruvate carboxylase in mistletoe leaves: regulation of gene expression, protein content, and covalent modification. | seasonal changes in the activity of phosphoenolpyruvate carboxylase (pepcase, ec 4.1.1.31), a key enzyme in the interaction of carbohydrate and nitrogen metabolism, were studied in leaves of the c3 semiparasitic mistletoe, viscum album, growing on different host trees. maximum extractable pepcase activities were higher in leaves of mistletoes growing on betula pendula and alnus glutinosa hosts compared with those on the conifers, abies alba and larix decidua. independent of host, maximum extract ... | 2001 | 11473691 |
| identification of processes governing long-term accumulation of 137cs by forest trees following the chernobyl accident. | the regularities of 137cs distribution in trees (pinus sylvestris and betula pendula) growing in different types of forest ecosystems were investigated. high levels of heterogeneity of 137cs activity concentrations in different parts of the trees, resulting from their varied metabolism have been shown. the data obtained demonstrate a non-uniform character of 137cs distribution along the trunks, which can be explained by radionuclide fixation by the xylem vessel walls and by geometry changes alon ... | 2001 | 11484781 |
| phenolics in selected european hardwood species by liquid chromatography-electrospray ionisation mass spectrometry. | the phenols in beech (fagus sylvatica), birch (betula pendula) and ash (fraxinus excelsior) wood dusts were compared using a mass spectrometer fitted with an electrospray ionisation interface with liquid chromatographic separation. hardwood dust is a carcinogen, and an analysis of the polyphenol profile is a useful method for identifying the dust source in workplace air. the mass spectrometer was operated in both the negative and positive ion modes. phenolic compounds were identified by comparin ... | 2001 | 11592645 |
| in situ net mineralization rates in a heterogeneous mixed deciduous forest receiving elevated n deposition. | in situ net mineralization was studied at 6 locations (e, eb, ec, f1, f2, f3) of a heterogeneous mixed deciduous forest ("de gulkeputten") with oak (quercus robur l., quercus rubra) and birch (betula pendula) as dominant species. net nitrogen mineralization was determined by means of a sequential in situ incubation experiment using intact soil cores. for all incubations, the net mineralization rates of the organic (f+h) layer varied between -0.4 and 2.0 g n m(-2) month(-1), while the net nitrifi ... | 2001 | 15952425 |
| uv-b absorbance and uv-b absorbing compounds (para-coumaric acid) in pollen and sporopollenin: the perspective to track historic uv-b levels. | uv-b absorbance and uv-b absorbing compounds (uacs) of the pollen of vicia faba, betula pendula, helleborus foetidus and pinus sylvestris were studied. sequential extraction demonstrated considerable uv-b absorbance both in the soluble (acid methanol) and insoluble sporopollenin (acetolysis resistant residue) fractions of uacs, while the wall-bound fraction of uacs was small. the uv-b absorbance of the soluble and sporopollenin fraction of pollen of vicia faba plants exposed to enhanced uv-b (10 ... | 2001 | 11693361 |
| container-grown tree seedling responses to sodium chloride applications in different substrates. | seedlings of norway maple (acer platanoides), silver birch (betula pendula), norway spruce (picea abies) and scots pine (pinus sylvestris) were grown in selected sodium chloride (nacl) concentrations, soil types and under different watering regimes. plants were raised from seeds, except for scots pine plants which were obtained from a commercial source. among the plant species tested, scots pine was the most tolerant to soil salinity, while norway spruce was the most susceptible. for both norway ... | 2000 | 15092891 |
| humus bacteria of norway spruce stands: plant growth promoting properties and birch, red fescue and alder colonizing capacity. | we studied the potential of the humus layer of the norway spruce stands to supply beneficial rhizobacteria to birch (betula pendula), alder (alnus incana) and fescue grass (festuca rubra), representatives of pioneer vegetation after clear-cutting of the coniferous forest. axenically grown seedlings of these species were inoculated with the acid spruce humus, ph 3.7-5.3. actinorhizal propagules, capable of nodulating alder, were present in high density (10(3) g(-1)) in humus of long-term limed pl ... | 2000 | 10640667 |
| effects of resource availability on carbon allocation and developmental instability in cloned birch seedlings. | abundant nitrogen improves seedling growth and establishment. vigorous growth brings about changes in rates and patterns of plant development and changes in the relationship between primary and secondary metabolism, which may make seedlings more susceptible to herbivores and pathogens than are slow-growing seedlings. we studied how nitrogen fertilization and manual defoliation of source leaves affect growth, carbon allocation, and developmental instability in cloned seedlings of white birch (bet ... | 2000 | 10648201 |
| substrate preference profiles of proteases released by allergenic pollens. | pollens are important triggers for allergic asthma and seasonal rhinitis. we have recently reported that proteases released by major allergenic pollens can injure airway epithelial cells in vitro. disruption of epithelial integrity by proteases released following deposition of pollens on mucosal surfaces could promote sensitization and induce inflammation. | 2000 | 10718856 |
| [cytogenetic characteristics of seed progeny of trees under condition of antropogenic contamination in voronezh town]. | it has been shown that in seed progeny of quercus robur l., pinus sylvestris l. and betula pendula roth. some cytogenetical characteristics vary under conditions of contamination. such changes may be common or specific type. thus, the frequency of pathological mitosis increases under such conditions in all the investigated species of trees. inhibition of mitosis was found in the progeny of the pine, and variability in the number of nucleoli was detected in the pine and oak. however, in some case ... | 2000 | 10752126 |
| chemometrics: an important tool for the modern chemist, an example from wood-processing chemistry | this study briefly outlines the idea of principal component analysis and cross-correlation calculations (applied chemometrics) and presents an illustrative example from wood-processing chemistry. the applicability of chemometric data analysis was demonstrated by investigating the various structural changes that take place in dissolved and degraded lignin ("kraft lignin") during laboratory-scale kraft pulping of scots pine (pinus sylvestris) and silver birch (betula pendula). the structural data ... | 2000 | 10761150 |
| functional analysis of a nitrite reductase promoter from birch in transgenic tobacco. | nitrate assimilation is a highly regulated process in higher plants, and the regulatory cues governing gene expression in this pathway include both external and internal factors. in birch (betula pendula roth) the expression of nitrate reductase (nr) and nitrite reductase (nir) genes is co-regulated by light and nitrate at the transcriptional level. in order to identify cis-acting dna-elements involved in light and nitrate induction of the birch nir gene, a 0.9 kb 5' flanking region of the nir g ... | 2000 | 10814817 |
| antimicrobial effects of finnish plant extracts containing flavonoids and other phenolic compounds. | plant phenolics, especially dietary flavonoids, are currently of growing interest owing to their supposed functional properties in promoting human health. antimicrobial screening of 13 phenolic substances and 29 extracts prepared from finnish plant materials against selected microbes was conducted in this study. the tests were carried out using diffusion methods with four to nine microbial species (aspergillus niger, bacillus subtilis, candida albicans, escherichia coli, micrococcus luteus, pseu ... | 2000 | 10857921 |
| effects of aluminium on the growth and mineral composition of betula pendula roth. | aluminium (al) is rhizotoxic and is often present in acidic soils at activities high enough to inhibit root elongation. the objectives of the present study were to assess the level of al tolerance in different races of betula pendula roth (silver birch) and to investigate how growth and nutrient acquisition were affected by al. a solution culture technique was employed which simulated natural soil solutions. aluminium at low concentrations (2 and 5 mg l(-1)), enhanced the growth of two races of ... | 2000 | 10948233 |
| strategies of a bark beetle, pityogenes bidentatus, in an olfactory landscape. | volatiles from leaves or bark of nonhost birch (betula pendula) and norway spruce (picea abies) dramatically reduced the attraction of the bark beetle, pityogenes bidentatus (coleoptera: scolytidae), to their aggregation pheromone components (cis-verbenol and grandisol) in the field. in addition, odors from both the needles and bark of the host scots pine (pinus sylvestris) similarly inhibited attraction. monoterpenes of pine and spruce (alpha-pinene, beta-pinene, terpinolene, and 3-carene) as w ... | 2000 | 11151671 |
| [radionuclide accumulation in fruit bodies of macromycetes]. | coefficients of 137cs accumulation and 90sr were determined in macromycetes of different trophic groups (137cs in 43 species and 90sr in 19 species) in the conditions of droughty year (1992). their variability in forest formations was determined in the period from 1992 to 1998. in the year with increased atmospheric humidity (1998), two-fold rise of 137cs accumulation in fruit bodies was registered on average. the pollution of boletus edulis correlates with photosynthetically active part of betu ... | 2000 | 11155341 |
| testing a process-based model of tree seedling growth by manipulating. | a model was developed that simulated photosynthesis, growth and allocation in tree seedlings. the model was parameterized with data from experiments on seedlings of sycamore (acer pseudoplatanus l.), sitka spruce (picea sitchensis (bong) carr.) and young birch trees (betula pendula roth.). in these experiments, co2 concentration ([co2]) and nutrient addition rate were varied. parameters quantifying nutrient uptake, translocation and starch synthesis were fitted, based on data from control treatm ... | 2000 | 11305461 |
| genetic transformation of silver birch (betula pendula) by particle bombardment. | we used in vitro callus and shoot cultures as target material for genetic transformation of silver birch (betula pendula roth) by particle bombardment. cultivation of in vitro shoot cultures before particle bombardment and a long selection period, combined with a high concentration of selective agent after bombardment, led to the production of transformed plantlets that were stable, and no escapes were found among the tree lines produced. clonal variation in transformation efficiency was found i ... | 2000 | 12651425 |
| photosynthetic utilization efficiency of absorbed photosynthetically active radiation by scots pine and birch forest stands in the southern taiga. | absorption and utilization of photosynthetically active radiation (par) were investigated in scots pine (pinus sylvestris l.) and birch (betula pendula roth.) stands that were 41 years old at the end of the experimental period. canopy depth of the scots pine stand was about half that of the birch stand (6.5 versus 11.0 m), but absorption of par was similar in the two stands. the scots pine forest canopy, with a leaf area index of 8.9, absorbed 90% of the incoming par (apar), whereas the birch fo ... | 2000 | 12651489 |
| characterization of pin m iii cdna in western white pine. | maximum accumulation of pin m iii protein in western white pine (pinus monticola dougl. ex d. don) needles occurred during the winter months. to characterize pin m iii, an expression cdna library from poly(a)+ mrna of needles was immunoscreened and the full length cdna was cloned. an open reading frame of 486 bases encodes a protein of 161 amino acid residues with a molecular mass of 18 kd and a predicted isoelectric point of 5.5. the deduced amino acid sequence had some similarities (37%) with ... | 2000 | 12651516 |
| statistical evaluation of bud development theories: application to bud burst of betula pendula leaves. | resampling methods were used to evaluate models based on alternative bud development theories applied to betula pendula roth data. statistical testing based on the bootstrap method showed that the mean square errors (mse) of the predicted bud-burst dates of two models, in which the start of ontogenetic development depended on dormancy development only, did not differ significantly. however, the mse of the model in which the start of ontogenesis depended on a signal from light climate, indicated ... | 1999 | 12651536 |
| biomass investment in leaf lamina versus lamina support in relation to growth irradiance and leaf size in temperate deciduous trees. | foliar biomass investment in support and assimilative compartments was studied in four temperate deciduous tree species along a natural light gradient across the canopy. the species ranked according to shade tolerance as betula pendula roth. < populus tremula l. < fraxinus excelsior l. < tilia cordata mill. long-term light conditions at sampling locations were characterized as seasonal mean integrated quantum flux density (q(int), mol m(-2) day(-1)) estimated by a method combining hemispherical ... | 1999 | 12651556 |
| growth and nutrition of betula pendula at different relative supply rates of zinc. | small birch plants (betula pendula roth) were cultivated in a hydroponic spray solution where the relative growth rate (r(g); day(-1)) was controlled by the relative supply rate of zinc (r(zn); day(-1)). after an adjustment phase to steady-state growth, r(g) equaled r(zn). the r(zn) treatments were 0.05, 0.125 and 0.20 day(-1) with free access to all other nutrients. in an additional treatment, there was free access to all nutrients, including zinc (fa treatment). the ph of the nutrient solution ... | 1999 | 12651590 |
| [dispersal of pollen and the variation in number of patients prescribed medicine for allergies in otaru]. | the number of patients prescribed medicine for allergies increased in may and september. therefore, we suspected that the cause for the increase was pollen. many kinds of pollen occur in otaru, such as alder in april, japanese black pine, white birch, acacia, larch in may, oak in june, and mugwort in september. the total number of pollen count of white birch was about 9 times that of mugwort, but the total number of patients prescribed celestamine in the season of white birch pollen was about 0. ... | 1999 | 10198596 |
| quantification of birch and grass pollen allergens in indoor air. | birch and grass pollen grains as well as pollen-derived small particles appear as potent allergens in the outdoor air during spring and summer. the occurrence of pollen allergens in indoor air, however, has not been studied in depth due to lack of suitable sampling and analytical methods. herein, a recently reported "direct on sampling filter estimation" (dosafe) technique (acevedo et al., 1998) has been validated for quantification of pollen allergens in indoor air using two school rooms and tw ... | 1999 | 10390933 |
| [a relationship between birch pollen and meteorological factors during the past four years and pollen survey in sapporo in 1997]. | it is well known that grass pollinosis has been the most representative pollinosis in hokkaido prefecture, japan, however, it is also well known that birch (japanese white birch, betula platyphylla var. japonica) pollinosis is gradually increasing, which is marked especially in sapporo and its neighborhood. we analyzed a relationship between the birch pollen count and meteorological factors statistically. moreover, the principal airborne pollen counts in sapporo in 1997 were assessed and compare ... | 1999 | 10481357 |
| host-driven population dynamics in an herbivorous insect. | understanding the nature and relative importance of endogenous (density-dependent) and exogenous (density-independent) effects on population dynamics remains a central problem in ecology. evaluation of these forces has been constrained by the lack of long time series of population densities and largely limited to populations chosen for their unique dynamics (e.g., outbreak insects). especially in herbivore populations, the relative contributions of bottom-up and top-down effects (resources and n ... | 1999 | 10485895 |
| microbial activities related to c and n cycling and microbial community structure in the rhizospheres of pinus sylvestris, picea abies and betula pendula seedlings in an organic and mineral soil. | the aim of this study was to determine whether scots pine (pinus sylvestris l.), norway spruce (picea abies (l.) karst.) and silver birch (betula pendula roth) seedlings have a selective influence on the soil microbial community structure and activity and whether this varies in different soils. seedlings of pine, spruce and birch were planted into pots of two soil types: an organic soil and a mineral soil. pots without seedlings were also included. after one growing season, microbial biomass c ( ... | 1999 | 10508943 |
| new bet v 1 isoforms including a naturally occurring truncated form of the protein derived from austrian birch pollen. | bet v 1, the major pollen allergen from white birch, displays a considerable degree of heterogeneity. until now, all molecular and immunological characterization studies of bet v 1 isoforms have been performed with commercially available pollen of swedish origin. in regard to clinical studies with austrian birch pollen allergic individuals, knowledge about the isoform repertoire in austrian birch pollen was necessary. cdnas coding for bet v 1 isoforms from austrian birch pollen were cloned by pc ... | 1999 | 10509815 |
| [the mechanisms of the anti-ulcer action of plant drug agents]. | the mechanisms of the gastroprotective effect of well-known drugs (plantaglucid, befungin, plantain juice), extractions of birch bark (betula pendula roth,) and burdock seeds (arctium tomentosum mill.) on various links of gastric ulcer pathogenesis were compared. phytopreparations were found to have a variety of effects on gastric secretion in rats. differences in their action on the smooth muscles of the stomach and intestine were detected. | 1999 | 10513334 |
| ammonium and methylamine transport by the ectomycorrhizal fungus paxillus involutus and ectomycorrhizas. | using [(14)c]methylamine as an analogue of ammonium, the kinetics and the energetics of nh(4)(+) transport were studied in the ectomycorrhizal fungus, paxillus involutus (batsch) fr. the apparent half-saturation constant (k(m)) and the maximum uptake rate (v(max)) for the carrier-mediated transport derived from the eadie-hofstee transformation were 180 µm and 380 nmol (mg dry wt)(-1) min(-1,) respectively. both ph dependence and inhibition by protonophores indicate that methylamine transport in ... | 1999 | 10568844 |
| short communication: subcellular localization of ozone-induced hydrogen peroxide production in birch (betula pendula) leaf cells. | the atmospheric air pollutant ozone (o3) is one of the environmental stresses that induce formation of reactive oxygen species (ros) in plants. previously, the toxicity of o3 has been believed to be a result of ros formation from o3-degradation. recently, however, it has been shown that o3 induces active ros production, which suggests that o3-responses may be mechanistically similar to pathogen-induced responses and that o3-damage could be a result of deleterious firing by the ros of pathways no ... | 1999 | 10571895 |
| population- and ecosystem-level effects of predation on microbial-feeding nematodes. | we studied the role of nematode predation in the functioning of detrital food webs assembled in microcosms. the microcosms contained defaunated humus and litter materials, a diverse microbial community with bacteria, fungi and protozoa, and a birch (betula pendula) seedling infected with mycorrhizal fungi. different levels of top-down control upon microbivorous nematodes were set up by assembling food webs either without predators, or in combinations with a specialist and a non-specialist predat ... | 1999 | 28308090 |
| the charcoal effect in boreal forests: mechanisms and ecological consequences. | wildfire is the principal disturbance regime in northern boreal forests, where it has important rejuvenating effects on soil properties and encourages tree seedling regeneration and growth. one possible agent of this rejuvenation is fire-produced charcoal, which adsorbs secondary metabolites such as humus phenolics produced by ericaceous vegetation in the absence of fire, which retard nutrient cycling and tree seedling growth. we investigated short-term ecological effects of charcoal on the bore ... | 1998 | 28308435 |
| effect of abscisic acid, cold hardening, and photoperiod on recovery of cryopreserved in vitro shoot tips of silver birch | recovery of cryopreserved in vitro shoot tips of silver birch (betula pendula roth) was doubled by incorporating abscisic acid (aba) in the culture medium during cold hardening of the mother shoots. the average recovery of shoot tips was over 40% after cold hardening for 28 days at +5 degreesc under an 8/16 light/dark photoperiod on medium containing 10(-4) m aba. aba was effective in combination with low temperature and short daylength only, although large genotypical differences were noted. ab ... | 1998 | 9500934 |
| visualization and quantification of birch-pollen allergens directly on air-sampling filters. | a new technique is presented to detect and quantify birch (betula pendula)-pollen allergens directly on air-sampling filters. it is based on the use of specific antibodies, enzymatic reactions, and measurement by chemiluminescence or densitometry. the major pollen antigens are the most important birch allergens. the antibodies used recognize birch-pollen antigens which thus correspond to allergens. calibration was done with a standardized extract of birch pollen for skin prick testing. the corre ... | 1998 | 9689341 |
| the griess assay: suitable for a bio-guided fractionation of anti-inflammatory plant extracts? | in the field of inflammation research the inducible nitric oxide synthase (inos) became an important pharmacological target, since overproduction of nitric oxide (no) after induction of this enzyme seems to be associated with numerous pathological conditions. no released from cells can be detected and quantified photometrically as its stable product nitrite by a simple colorimetric reaction (griess reaction). the aim of our study was to investigate whether this method might be suitable for the b ... | 1998 | 9690344 |
| accumulation of flavonoids and related compounds in birch induced by uv-b irradiance. | a growth chamber experiment was conducted to examine the effects of uv-b exposure (4.9 kj m(-2) day(-1) of biologically effective uv-b, 280-320 nm) on shoot growth and secondary metabolite production in betula pendula (roth) and b. resinifera (britt.) seedlings originating from environments in finland, germany and alaska differing in solar uv-b radiation and climate. neither shoot growth nor the composition of secondary metabolites was affected by uv-b irradiance, but the treatment induced signi ... | 1998 | 12651299 |
| long-term photosynthetic acclimation to increased atmospheric co(2) concentration in young birch (betula pendula) trees. | to study the long-term response of photosynthesis to elevated atmospheric co(2) concentration in silver birch (betula pendula roth.), 18 trees were grown in the field in open-top chambers supplied with 350 or 700 &mgr;mol mol(-1) co(2) for four consecutive growing seasons. maximum photosynthetic rates, stomatal conductance and co(2) response curves were measured over the fourth growing season with a portable photosynthesis system. the photosynthesis model developed by farquhar et al. (1980) was ... | 1998 | 12651355 |
| stomatal conductance, growth and root signaling in betula pendula seedlings subjected to partial soil drying. | seedlings of betula pendula roth were grown with their root systems separated between two soil compartments. four treatments were imposed: (i) adequate irrigation in both compartments (ww, controls); (ii) adequate irrigation in one compartment and drought in the other compartment (wd); (iii) drought in both compartments (dd); and (iv) half of the root system severed and the remainder kept well-watered (root excision, re). predawn leaf water potential, stomatal conductance, soil-to-leaf specific ... | 1998 | 12651411 |
| effects of dormancy and environmental factors on timing of bud burst in betula pendula. | we tested three theories predicting the timing of bud burst in mature birch (betula pendula roth) trees utilizing a 60-year phenological time series together with meteorological temperature observations. predictions of the timing of bud burst based on light conditions in addition to temperature were more accurate than predictions based on dormancy development and temperature (prediction standard error of 2.4 days versus 4.3 days). the signal from light conditions, represented by fixed calendar d ... | 1998 | 12651420 |
| effects of light quality on growth and n accumulation in birch seedlings. | we studied the effects of light quality and nutrient supply on growth and nitrogen accumulation in silver birch (betula pendula roth) seedlings to test three hypotheses: (1) growth of birch seedlings is sensitive to changes in light quality; (2) the response of birch seedling growth to light quality depends on nutrient supply; and (3) assimilation and allocation of nitrogen by birch seedlings are affected by light quality. the two light regimes simulated the spectral quality of sunlight and shad ... | 1997 | 14759882 |
| isolation and characterization of cdna for a plant mitochondrial phosphate translocator (mpt1): ozone stress induces mpt1 mrna accumulation in birch (betula pendula roth). | we have isolated by ddrt-pcr (differential-display reverse-transcription polymerase chain reaction) and cdna library screening a 1.3 kb cdna corresponding to a strongly ozone-inducible transcript from birch (betula pendula roth). nucleotide sequence analysis suggests that it encodes a mitochondrial phosphate translocator protein (pic), the first one isolated from plants. the isolated birch mitochondrial phosphate translocator cdna (designated mpt1) contains an open reading frame of 1092 bases en ... | 1997 | 9349251 |
| effects of air pollution and other environmental factors on birch pollen allergens. | to determine the effects of anthropogenic pollution on water-soluble proteins and specifically allergens in birch (betula pendula and b. pubescens) pollen, we analyzed extracts of pollen from the pollution gradient around a factory complex (emitting sulfur oxides and heavy metals) by sodium dodecyl sulfate (sds)--polyacrylamide gel electrophoresis (page) and ige immunoblotting. in addition, tree density-associated shading of the tree habitat, and quantity and quality of proteins and allergens in ... | 1997 | 9450140 |
| differences in growth, leaf senescence and injury, and stomatal density in birch (betula pendula roth.) in relation to ambient levels of ozone in finland. | the differences in growth, leaf senescence, visible ozone injuries and stomatal density between one coastal site (natural ozone) and two inland sites (natural and elevated ozone) in finland were determined for saplings of betula pendula clones grown under open-field conditions during two growing seasons. responses in growth, leaf senescence, visible injuries, and stomatal density were determined in relation to cumulative ozone exposure accumulated over the thresholds of 30, 40 and 50 ppb (10(9)) ... | 1997 | 15093411 |
| antioxidant responses to simulated acid rain and heavy metal deposition in birch seedlings. | this study measured the responses of different anti-oxidants in 2-year-old birch (betula pendula roth) seedlings subjected to simulated acid rain (ph 4.0) and heavy metals (cu/ni), applied alone or in combination for 2 months. the applied concentrations of pollutants did not significantly affect seedling biomass or total glutathione levels. acid rain alone increased superoxide dismutase (sod) activity both in leaves and roots, while heavy metals alone inhibited sod activity in roots. both acid r ... | 1997 | 15093466 |
| variation in ozone sensitivity among clones of betula pendula and betula pubescens. | forty clones of betula pendula and 6 clones of betula pubescens, originating from southern and central finland, were ranked in order of ozone sensitivity according to visible injuries, growth and leaf senescense under low ozone exposure. the plants were fumigated in natural climatic conditions using an open-air exposure system during two growing seasons. control plants were grown under ambient air, and the elevated-ozone exposures were 1.6x the ambient in 1994 and 1.7x the ambient in 1995. the d ... | 1997 | 15093472 |
| new dammaranes, esterified with malonic acid, from leaves of betula pendula. | three known and five new dammarane triterpenes, esterified with malonic acid at c-3 with hemolytic activity were identified from the ethanol-water extract of leaves of betula pendula roth: 12-o-acetyl-3alpha,12beta,20(s),24(r)-tetrahydroxydammar-25-en-3-yl hydrogen propanedioate, 12-o-acetyl-3alpha,12beta20(s),24(s)-tetrahydroxydammar-25-en-3-yl hydrogen propanedionate, 12-o-acetyl-3alpha,12beta,17alpha,20(s),24(r)-pentahydroxydammar-25-en-3-yl hydrogen propanedioate, [12beta-acetoxy-4,4,8,10,14 ... | 1997 | 17252393 |
| regenerating temperate forest mesocosms in elevated co2: belowground growth and nitrogen cycling. | the response of temperate forest ecosystems to elevated atmospheric co2 concentrations is important because these ecosystems represent a significant component of the global carbon cycle. two important but not well understood processes which elevated co2 may substantially alter in these systems are regeneration and nitrogen cycling. if elevated co2 leads to changes in species composition in regenerating forest communities then the structure and function of these ecosystems may be affected. in mos ... | 1997 | 28307286 |
| herbivore-induced resistance in betula pendula: the role of plant vascular architecture. | we studied the role of plant vascular architecture in the determination of the spatial extent of herbivore induced responses within betula pendula roth saplings. the induced responses were measured in bioassays in terms of the relative growth rate of larvae of a geometrid moth, epirrita autumnata. we hypothesised that the level of induced resistance of a certain leaf would be determined by the degree of vascular connectivity between the leaf in question and a damaged leaf, as suggested by recent ... | 1996 | 28307807 |
| elevated co2 reduces field decomposition rates of betula pendula (roth.) leaf litter. | the effect of elevated atmospheric co2 and nutrient supply on elemental composition and decomposition rates of tree leaf litter was studied using litters derived from birch (betula pendula roth.) plants grown under two levels of atmospheric co2 (ambient and ambient +250 ppm) and two nutrient regimes in solar domes. co2 and nutrient treatments affected the chemical composition of leaves, both independently and interactively. the elevated co2 and unfertilized soil regime significantly enhanced lig ... | 1996 | 28307453 |
| allozyme variation in populations, full-sib families and selfed lines in betula pendula roth. | changes in genetic variability in populations (stand origins), full-sib (fs) families and three generations of selfed lines of betula pendula were observed based on 15 allozyme loci. growth vigour, measured as stem volume, and its relationship with heterozygosity was studied to determine the effect of inbreeding. pooled fs families showed a higher percentage of polymorphic loci (p) and allelic numbers per locus (a) than those of natural populations, but no difference in heterozygosity. there was ... | 1996 | 24166635 |
| effects of bilberry (vaccinium myrtillus l.) litter on seed germination and early seedling growth of four boreal tree species. | laboratory and greenhouse bioassays were used to test for inhibitory effects of senescent and decomposed leaves and aqueous extract from bilberry (vaccinium myrtillus l.) against seed germination and seedling growth of aspen (populus tremula l.), birch (betula pendula roth.), scots pine (pinus sylvestris l.), and norway spruce [picea abies (l.) karst.]. aqueous extracts from bilberry leaves were inhibitory to aspen seed germination and seedling growth and also induced root damage and growth abno ... | 1996 | 24227618 |
| effect of birch (betula pendula) bark and food protein level on root voles (microtus oeconomus): ii. detoxification capacity. | the effect of protein and birch bark powder (bbp) content of forage on detoxification capacity of root voles (microtus oeconomus) was studied. young voles were fed with eight different diets for two weeks. individuals on low (3%) protein diets had significantly lighter livers and kidneys than those on moderate (6%) or high (12%) protein diets. birch bark powder addition did not have significant effect on organ weight. detoxification was significantly induced, apparently due to secondary compound ... | 1996 | 24227580 |
| effect of birch (betula pendula) bark and food protein level on root voles (microtus oeconomus): i. food consumption, growth, and mortality. | the effect of protein and birch bark powder (bbp) content of forage on food consumption and growth of root voles (microtus oeconomus) was studied by feeding young voles with eight different diets for two weeks. voles ate more when the protein content of forage was moderate (6%) or low (3%), and when bbp was added to the diets, as compared to a high (12%) protein diet without bbp addition. on high and moderate protein diets voles gained weight, whereas on low protein diets they lost weight. addit ... | 1996 | 24227579 |
| xylem dysfunction during winter and recovery of hydraulic conductivity in diffuse-porous and ring-porous trees. | xylem embolism in winter and spring as well as the occurrence of positive xylem pressure were monitored in several diffuse-porous and one ring-porous tree species (fraxinus excelsior). in acer pseudoplatanus and betula pendula embolism reversal was associated with positive (above-atmospheric) xylem pressures that frequently occurred during a 2-month period prior to leaf expansion. in acer high stem pressures were occasionally triggered on sunny days after a night frost. the other species investi ... | 1996 | 28307135 |
| growth performance of hybrid families by crossing selfed lines of betula pendula roth. | hybrid breeding is an effective approach in many agricultural crops. in allogamous tree species severe inbreeding depression and long reproductive cycles generally prohibit its use. however, three generations of selfing in silver birch (betula pendula roth) were obtained by forcing trees to flowering under greenhouse conditions. hybrids were produced by crossing first-, second and third-generation selfed lines. the effects of different levels of parental inbreeding on the growth performance of h ... | 1996 | 24166273 |
| preseasonal intranasal immunotherapy in birch-alder allergic rhinitis. a double-blind study. | a double-blind, placebo-controlled study was carried out to test the clinical efficacy and safety of local nasal immunotherapy (lnit) in powder form. twenty-two patients suffering from allergic rhinitis strictly associated with early spring symptoms, with positive skin prick tests and rast for birch-alder, all responders to a specific nasal provocation test (npt), received randomly active or placebo treatment for 4 months. immunotherapy consisted of administration of a set of capsules containing ... | 1996 | 8836333 |
| characterization of purified recombinant bet v 1 with authentic n-terminus, cloned in fusion with maltose-binding protein. | a gene encoding the pollen major allergen bet v 1 from betula verrucosa (white birch) has been cloned and expressed in escherichia coli as a fusion with maltose-binding protein and a factor xa proteolytic cleavage site. a generally applicable cloning strategy based on polymerase chain reaction was designed to position the factor xa proteolytic site so that the authentic amino terminus of bet v 1 was generated after cleavage. fusion protein was isolated by amylose affinity chromatography and enzy ... | 1996 | 8936599 |
| crystallization and preliminary x-ray investigation at 2.0 a resolution of bet v 1, a birch pollen protein causing ige-mediated allergy. | the 17 kda protein from betula verrucosa (white birch) pollen, bet v 1, is the clinically most important birch pollen allergen causing immediate type i ige-mediated allergy. the three-dimensional structure of bet v 1 and its ige-binding epitopes are at present not known. in addition, the biological function of bet v 1 in birch pollen is not fully established. in this work, bet v 1 has been expressed in escherichia coli as a recombinant protein, purified and crystallized. the space group of recom ... | 1996 | 8953655 |
| [standardization of the birch leaf]. | dried leaves of betula pendula roth (14 batches) and b. pubescens ehrh. (3 batches) present a similar flavonoid pattern. the mean levels of the principal flavonoid compounds were respectively: total flavonoids 3.29 and 2.77%, hyperoside 0.80 and 0.77%, avicularin (two forms) 0.57 and 0.26%, galactosyl-3 myricetol 0.37 and 0.18%, glucuronyl-3 quercetol 0.25 and 0.36%, quercitrin 0.14 and 0.12%. the flavonoid levels were higher in young leaves and lower in old leaves of b. pendula. 14 batches of c ... | 1996 | 8953799 |
| a natural experiment on plant acclimation: lifetime stomatal frequency response of an individual tree to annual atmospheric co2 increase. | carbon dioxide (co2) has been increasing in atmospheric concentration since the industrial revolution. a decreasing number of stomata on leaves of land plants still provides the only morphological evidence that this man-made increase has already affected the biosphere. the current rate of co2 responsiveness in individual long-lived species cannot be accurately determined from field studies or by controlled-environment experiments. however, the required long-term data sets can be obtained from co ... | 1996 | 11607712 |
| growth responses and related biochemical and ultrastructural changes of the photosynthetic apparatus in birch (betula pendula) saplings exposed to low concentrations of ozone. | saplings of ozone-sensitive and ozone-tolerant birch (betula pendula roth.), clones b and c, respectively, were exposed to ozone concentrations that were 1.7-fold higher than ambient for one growing season under open-field conditions. ambient air was used as the control treatment. in the ozone-sensitive clone b, there was an initial stimulation of leaf area growth in response to the ozone treatment, but further ozone exposure caused reductions in leaf and stem biomass growth, rubisco and chlorop ... | 1996 | 14871697 |
| improving the reliability of a combined phenological time series by analyzing observation quality. | collecting phenological data is a slow process. although such data have been collected by a number of organizations, the reliability of these data is not known because the data-generating process cannot be repeated. no further observations to improve the reliability can be obtained. however, the data usually consist of several overlapping observation series and this overlap can be utilized to construct a combined phenological time series and to improve its reliability. we have developed two tech ... | 1996 | 14871705 |
| micropropagation of adult birch trees: production and field performance. | we compared the growth of trees produced by micropropagation from nodal stem sections or callus tissue of a 20-year-old silver birch (betula pendula roth) tree with that of seedlings; growth was monitored for 17 months in pots followed by six years in the field. micropropagated trees from both nodal stem sections and callus tissue grew at a similar rate to seedling trees and no obvious mutant types were observed. however, micropropagated trees were more uniform in height and trunk girth than see ... | 1996 | 14871723 |
| comparison of the photosynthetic capacity of siberian and japanese birch seedlings grown in elevated co(2) and temperature. | the effects of increased co(2) and temperature on the photosynthetic capacity of siberian white birch and japanese white birch (betula platyphylla sukatch. and b. platyphylla sukatch. var. japonica hara) were measured. birch seedlings were raised with a co(2) partial pressure of 36 +/- 0.3 pa (i.e., ambient) or 70 +/- 0.6 pa at day/night temperatures of either 30/16 degrees c or 26/12 degrees c. siberian birch leaves were smaller and thicker than japanese birch leaves. water use efficiency and n ... | 1996 | 14871740 |
| impacts of water and nitrogen supplies on the physiology, leaf demography and nitrogen dynamics of betula pendula. | we determined the response of betula pendula roth. trees to a restricted water supply, and quantified the interactions between tree n and water status on leaf demography and internal n cycling. in april 1993, 3-year-old trees were planted in sand culture and four treatments applied: high-n supply (56 mg tree(-1) week(-1)) with either 2 dm(3) water week(-1) (hn+) or 0.9 dm(3) water week(-1) (hn-), or low-n supply (14 mg tree(-1) week(-1)) with 2 dm(3) (ln+) or 0.9 dm(3) (ln-) water week(-1). unti ... | 1996 | 14871759 |