SEARCH · PubMed Health

Results for “Fraxinus”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 145 records · Page 8Linked to original sources

PubMed1968

Abscisic Acid levels and seed dormancy.

Dormant seeds from Fraxinus species require cold-temperature after-ripening prior to germination. Earlier, we found that abscisic acid (ABA) will inhibit germination of excised nondormant embryos and that this can be reversed with a combination of gibberellic acid and kinetin. Using Milborrow's quantitative "racemate dilution" method the ABA concentration in 3 types of Fraxinus seed and pericarp were determined. While ABA was present in all tissues, the highest concentration was found in the seed and pericarp of dormant F. americana. During the chilling treatment of F. americana the ABA levels decreased 37% in the pericarp and 68% in the seed. The ABA concentration of the seed of the nondormant species, F. ornus, is as low as that found in F. americana seeds after cold treatment. Experiments with exogenously added ABA solutions indicate that it is unlikely that the ABA in the pericarp functions in the regulation of seed dormancy. However, the ABA in the seed does seem to have a regulatory role in germination.

Journal Article↗

PubMed1997

Cross-reactivity of Olea europaea with other Oleaceae species in allergic rhinitis and bronchial asthma.

Cross-reactivity between pollen extracts of four species of Oleaceae was studied: olive (Olea europaea), ash (Fraxinus excelsior), privet (Ligustrum vulgare), and lilac (Syringa vulgaris). Thus, 51 patients and 13 atopic controls were studied, by means of intracutaneous skin tests, histamine-release tests against the four extracts, and specific IgE to O. europaea. The proteic content of the four extracts was assessed by SDS-PAGE and immunoblotting, and similarity of all the extracts studied was observed after electrophoresis and immunodetection. Six common bands were found to be responsible for the cross-reactivity, with apparent molecular weights of 49.6, 40, 36.7, 19.7, 16.7, and 14 kDa, respectively. The cross-reactivity was also corroborated by immunoblotting inhibition and FEIA inhibition. The patients had a similar response to the four allergenic extracts used, although the response to Olea was greatest. When the patients were compared by their geographic origin (northern or southern Spain, according to the distribution of areas of olive pollen influence), there were no significant differences between the two groups in skin reactivity, but a higher histamine release was observed for the four extracts in the southern group, although it was significant only for Fraxinus and Ligustrum. This work corroborated the practicality of the diagnostic methods used and the cross-reactivity between the four species studied, as demonstrated by the different methods used. Therefore, we suggest that only O. europaea extract be used in diagnosis and immunotherapy in Oleaceae pollen allergy.

Adult↗

PubMedDate not supplied

Inhibition by Salix- extracts and Phytodolor of copper-catalyzed oxidative destruction.

Oxidation of low density lipoprotein (LDL) by copper ions is strongly inhibited by different aqueous extracts (Salix spec (SE); Fraxinus-Dolidago-Populus (Phytodolor)(PD) in a concentration range between 4 and 7 micrograms/ml. 10 to 50 microM salicylic acid (SA) stimulate LDL-oxidation whereas higher concentrations (10 to 500 micromM) showed no effect. Likewise ethene release from 2-keto-4-methylthiobutyrate (KMB) is strongly inhibited by the above extracts in a reaction driven by dihydroxyfumarate (DHF) in the presence of copper ions. This system may represent some features of the diabetic situation where DHF as an endiole may stand for certain Amadori products. In order to find out whether the inhibitory effects are due to copper chelation we tested the copper-dependent conversion of photodynamic ethane release from alpha-linolenic acid into ethene formation. Copper chelation is apparently only partially involved in inhibition of copper-dependent oxidations and only at a certain concentration of extracts from salix spec (SE) or extracts from Fraxinus-Solidago-Populus (Phytodolor)(PD).

Antioxidants↗

PubMed2001

Nutrient and heavy metal uptake and storage in constructed wetland systems in Arizona.

The Constructed Ecosystems Research Facility (CERF) was conceived in the early 1980s as a test facility to explore the potential for using plants to treat wastewater in the arid west of the USA. One of the major issues that has been identified in the use of constructed wetland technology is plant nutrient uptake and tissue storage of nutrients as well as heavy metals. Our approach to understanding plant uptake and storage has been to look at both controlled conditions in constructed systems and background concentrations in natural systems. Plant tissues have been collected and analyzed from natural systems and from controlled systems receiving either wastewater or municipal water. Plants studied included the herbaceous species Anemopsis californica (Yerba mansa), Scirpus spp. (bulrush) and Typha domingensis (cattail), and tree species Fraxinus velutina (ash), Populus fremontii (cottonwood) and Salix spp. (willow). Data indicate that uptake varies not only among plant species, but also among chemical species, depending upon water quality within the wetlands. Leaf tissues of Fraxinus, Salix and Populus, contained the lowest amounts of nutrients and heavy metals studied (Na, P, K, Cu, Pb and Zn), while the root tissues of the herbaceous plants generally had the highest concentrations.

Ecosystem↗

PubMed2004

Airborne pollen calendar of Lublin, Poland.

Pollen concentration in the atmosphere of Lublin (eastern Poland) was studied by means of volumetric method using Hirst sampler (VPPS 2000, Lanzoni) in 2001-2002. The pollen trap was mounted at the height of 15 m in the centre of Lublin. On the basis of analysis of mean daily values of pollen concentration, the pollen calendar was constructed for 16 taxa producing the allergenic pollen: Alnus, Corylus, Populus, Ulmus, Fraxinus, Betula, Carpinus, Quercus, Fagus, Pinaceae, Poaceae, Rumex, Plantago, Chenopodiaceae, Artemisia, Urticaceae. Great differences referring to the course of pollen seasons for most of the studied taxa of trees within the 2 years of study were found. They were associated with the beginning and end of the pollen season, the amount and the date of maximum pollen concentration occurrence, as well as annual sums of pollen grains. Much lower differentiation was observed in the case of herbaceous plants. This referred mainly to maximum concentration occurrence dates (Urtica, Poaceae) and the length of pollen season (Chenopodiaceae). The most similar course of pollen seasons during 2 years was recorded for Artemisia. Among trees, the highest pollen concentrations were recorded for Betula, Pinaceae and Alnus; the lowest for Ulmus, Fagus and Corylus. Very high concentration of herbaceous plant's pollen was observed for Poaceae and Urtica; Plantago and Chenopodiaceae showed the lowest level. Annual sums of pollen grains for Alnus, Populus, Quercus, Betula and Pinaceae were much higher in 2001, but in the case of Ulmus, Fraxinus, Carpinus, Fagus the annual sums of pollen grains in 2002 were almost twice as high as in 2001. For 5 among 7 herbaceous taxa, annual sums of pollen grains in both years were similar.

Air Pollutants↗

PubMed2004

Phaeoacremonium rubrigenum--hyphomycete associated with bark beetles found in Czechia.

Phaeoacremonium is a recently described genus (Crous et al. 1996) associated with decline diseases of woody hosts and with human infections. During a study of surface mycobiota of the oak bark beetles, the hyphomycetous microfungus Phaeoacremonium rubrigenum was isolated from larvae of Scolytus intricatus (Coleoptera: Scolytidae) and their galleries on Quercus robur and also from an adult of Leperisinus fraxini found under the bark of Fraxinus excelsior. The species determination was confirmed by rDNA (ITS1-5.8S-ITS2) comparison. P. rubrigenum was recorded for the first time in Czechia. The records on oak are considered to be the first ones in the world. A description of morphological features and figures of the fungus are given. Representative strains are maintained in the Culture Collection of Fungi (CCF), Faculty of Science, Charles University (Prague, Czechia).

Animals↗

PubMed2006

Leaf anatomy and light acclimation in woody seedlings after gap formation in a cool-temperate deciduous forest.

The photosynthetic light acclimation of fully expanded leaves of tree seedlings in response to gap formation was studied with respect to anatomical and photosynthetic characteristics in a natural cool-temperate deciduous forest. Eight woody species of different functional groups were used; two species each from mid-successional canopy species (Kalopanax pictus and Magnolia obovata), from late-successional canopy species (Quercus crispula and Acer mono), from sub-canopy species (Acer japonicum and Fraxinus lanuginosa) and from vine species (Schizophragma hydrangeoides and Hydrangea petiolaris). The light-saturated rate of photosynthesis (Pmax) increased significantly after gap formation in six species other than vine species. Shade leaves of K. pictus, M. obovata and Q. crispula had vacant spaces along cell walls in mesophyll cells, where chloroplasts were absent. The vacant space was filled after the gap formation by increased chloroplast volume, which in turn increased Pmax. In two Acer species, an increase in the area of mesophyll cells facing the intercellular space enabled the leaves to increase Pmax after maturation. The two vine species did not significantly change their anatomical traits. Although the response and the mechanism of acclimation to light improvement varied from species to species, the increase in the area of chloroplast surface facing the intercellular space per unit leaf area accounted for most of the increase in Pmax, demonstrating the importance of leaf anatomy in increasing Pmax.

Acclimatization↗

PubMed2005

Seasonal trends in reduced leaf gas exchange and ozone-induced foliar injury in three ozone sensitive woody plant species.

Seasonal trends in leaf gas exchange and ozone-induced visible foliar injury were investigated for three ozone sensitive woody plant species. Seedlings of Populus nigra L., Viburnum lantana L., and Fraxinus excelsior L. were grown in charcoal-filtered chambers, non-filtered chambers and open plots. Injury assessments and leaf gas exchange measurements were conducted from June to October during 2002. All species developed typical ozone-induced foliar injury. For plants exposed to non-filtered air as compared to the charcoal-filtered air, mean net photosynthesis was reduced by 25%, 21%, and 18% and mean stomatal conductance was reduced by 25%, 16%, and 8% for P. nigra, V. lantana, and F. excelsior, respectively. The timing and severity of the reductions in leaf gas exchange were species specific and corresponded to the onset of visible foliar injury.

Air Pollutants↗

PubMed2006

Assessing the potential of native tree species for carbon sequestration forestry in Northeast China.

Although the native forests of China are exceptionally diverse, only a small number of tree species have been widely utilized in forest plantations and reforestation efforts. We used dendrochronological sampling methods to assess the potential growth and carbon sequestration of native tree species in Jilin Province, Northeast China. Trees were sampled in and near the Changbaishan Biosphere Reserve, with samples encompassing old-growth, disturbed forest, and plantations. To approximate conditions for planted trees, sampling focused on trees with exposed crowns (dominant and co-dominant individuals). A log-linear relationship was found between diameter increment and tree diameter, with a linear decrease in increment with increasing local basal area; no significant differences in these patterns between plantations and natural stands were detected for two commonly planted species (Pinus koraiensis and Larix olgensis). A growth model that incorporates observed feedbacks with individual tree size and local basal area (in conjunction with allometric models for tree biomass), was used to project stand-level biomass increment. Predicted growth trajectories were then linked to the carbon process model InTEC to provide estimates of carbon sequestration potential. Results indicate substantial differences among species, and suggest that certain native hardwoods (in particular Fraxinus mandshurica and Phellodendron amurense), have high potential for use in carbon forestry applications. Increased use of native hardwoods in carbon forestry in China is likely to have additional benefits in terms of economic diversification and enhanced provision of "ecosystem services", including biodiversity protection.

Biodiversity↗

PubMed2005

The early stages of three Palaearctic species of saproxylic hoverflies (Syrphidae, Diptera).

The third stage larva and puparium of the cerioidine hoverflies, Ceriana vespiformis (Latreille, 1804) and Sphiximorpha subsessilis (Illiger in Rossi, 1807) and the milesine, Spilomyia digitata (Rondani, 1865) (Diptera, Syrphidae) are described from specimens collected in the field. Ceriana vespiformis and S. digitata larvae were obtained from wet, decaying roots and tree holes of Fraxinus angustifolius L., respectively, in Spain and S. subsessilis from an exudation of sap on an Abies alba Miller tree in France.

Abies↗

PubMed2004

Metal uptake by young trees from dredged brackish sediment: limitations and possibilities for phytoextraction and phytostabilisation.

Five tree species (Acer pseudoplatanus L., Alnus glutinosa L. Gaertn., Fraxinus excelsior L., Populus alba L. and Robinia pseudoacacia L.) were planted on a mound constructed of dredged sediment. The sediment originated from a brackish river mouth and was slightly polluted with heavy metals. This preliminary study evaluated the use of trees for site reclamation by means of phytoextraction of metals or phytostabilisation. Although the brackish nature of the sediment caused slight salt damage, overall survival of the planted trees was satisfactory. Robinia and white poplar had the highest growth rates. Ash, maple and alder had the highest survival rates (>90%) but showed stunted growth. Ash, alder, maple and Robinia contained normal concentrations of Cd, Cu, Pb and Zn in their foliage. As a consequence these species reduce the risk of metal dispersal and are therefore suitable species for phytostabilisation under the given conditions. White poplar accumulated high concentrations of Cd (8.0 mg kg(-1)) and Zn (465 mg kg(-1)) in its leaves and might therefore cause a risk of Cd and Zn input into the ecosystem because of autumn litter fall. This species is thus unsuitable for phytostabilisation. Despite elevated metal concentrations in the leaves, phytoextraction of heavy metals from the soil by harvesting stem and/or leaf biomass of white poplar would not be a realistic option because it will require an excessive amount of time to be effective.

Acer↗

PubMed2003

Uptake of 207Pb and 111Cd through bark of mature sugar maple, white ash and white pine: a field experiment.

A field study was undertaken to determine whether 207Pb and 111Cd, applied to the exterior bark of sugar maple (Acer saccharum Marsh.), white ash (Fraxinus americana L.) and white pine (Pinus strobus L.), could enter xylem tissue. Stable isotope tracers (3 microg Pb ml(-1); 2 microg Cd ml(-1)) were applied separately to bark in simulated rainfall, acidified to pH 4.5, in multiple doses over a 4 month (July-October) period. Tree cores were extracted from the region of application in the following March, and Pb and Cd isotopes were measured in bark and the outer tree rings using inductively coupled plasma mass spectrometry. The majority of the applied stable isotope tracer recovered (over 94%) was present in bark tissue, although a small amount of each metal tracer entered the outer (1-3) tree rings in all trees. Despite high concentrations of excess 207Pb in bark (up to 50 microg g(-1)), the maximum concentration of excess 207Pb measured in tree rings was only around 50 ng g(-1), which represents less than 30% of the background Pb concentration in wood at the study site. High excess 111Cd concentrations in bark (up to 35 microg g(-1)) also resulted in small increases in 111Cd in wood (up to 50 ng g(-1)), but due to lower background Cd concentrations in wood, such increases more than doubled the amount of Cd in wood compared with background levels. However, at sites where such high bark Cd concentrations are found, uptake from Cd-contaminated soil would probably be much greater than found at our study site. It appears that Cd and Pb applied to bark can enter woody tissue, but that this route of uptake is likely to be a minor contributor to the metal burden in wood.

Acer↗

PubMed2026

European ash pangenome reveals widespread structural variation and genetic basis of low ash dieback susceptibility.

European Ash (Fraxinus excelsior) is a keystone tree species, whose populations are being decimated by ash dieback disease (ADB) - better characterisation of genetic variants associated with low susceptibility to the disease is needed. Here, we develop a F. excelsior pangenome to more fully capture sequence variability within this species compared with a linear reference genome, using a geographically diverse set of fifty F. excelsior samples. We identify 362,965 structural variants (SVs), including 174 Mb of sequence absent from the linear reference genome (22% of the linear reference size), and identify 3,412 high-confidence dispensable genes (those present only in some individuals). We use the pangenome to analyse existing genomic data from over 1,200 individuals, revealing 220 single nucleotide polymorphisms (SNPs) showing consistent allele frequency shifts between healthy individuals and those highly damaged by ADB, across UK seed sources, explicitly demonstrating the existence of a shared genetic component to low ADB susceptibility.

Polymorphism, Single Nucleotide↗

PubMed2003

Estimating seed vs. pollen dispersal from spatial genetic structure in the common ash.

Spatial genetic structure was analysed with five highly polymorphic microsatellite loci in a Romanian population of common ash (Fraxinus excelsior L.), a wind-pollinated and wind-dispersed tree species occurring in mixed deciduous forests over almost all of Europe. Contributions of seed and pollen dispersal to total gene flow were investigated by analysing the pattern of decrease in kinship coefficients among pairs of individuals with geographical distance and comparing it with simulation results. Plots of kinship against the logarithm of distance were decomposed into a slope and a shape component. Simulations showed that the slope is informative about the global level of gene flow, in agreement with theoretical expectations, whereas the shape component was correlated with the relative importance of seed vs. pollen dispersal. Hence, our results indicate that insights into the relative contributions of seed and pollen dispersal to overall gene flow can be gained from details of the pattern of spatial genetic structure at biparentally inherited loci. In common ash, the slope provided an estimate of total gene dispersal in terms of Wright's neighbourhood size of Nb = 519 individuals. No precise estimate of seed vs. pollen flow could be obtained from the shape because of the stochasticity inherent to the data, but the parameter combinations that best fitted the data indicated restricted seed flow, sigmas pound 14 m, and moderate pollen flow, 70 m pound sigmap pound 140 m.

Computer Simulation↗

PubMed2004

Changes in pit membrane porosity due to deflection and stretching: the role of vestured pits.

The effect of increasing pressure difference (DeltaP) on intervessel pit membrane porosity was studied in two angiosperm tree species with differing pit architecture. Fraxinus americana L. possesses typical angiosperm bordered pit structure while Sophora japonica L. exhibits well-developed vestures in intervessel pit chambers. It was hypothesized (a) that large DeltaP across intervessel pits would cause the deflection of pit membranes in the stems of F. americana resulting in significant increases in porosity and thus lower cavitation thresholds, and (b) that the presence of vestures would prevent the deflection of pit membranes in S. japonica. To determine if the porosity of pit membranes increased under mechanical stress, suspensions of colloidal gold, 5 nm and 20 nm in diameter, were perfused across intervessel pit membranes at DeltaP ranging from 0.25 MPa to 6.0 MPa. The effect of increasing DeltaP on membrane porosity was also tested by comparing air seeding thresholds (Pa) in stems perfused with water or a solution with lower surface tension. Air seeding and colloidal gold experiments indicated that pit membrane porosity increased significantly with DeltaP in F. americana. In S. japonica, increases in permeability to colloidal gold with DeltaP were small and maximum pore diameters predicted from Pa were independent of DeltaP, suggesting that vestures limited the degree to which the membrane can be deflected from the centre of the pit cavity. This provides the first experimental evidence that vestures reduce the probability of air seeding through pit membranes.

Air↗

PubMed2004

Photosynthesis, carbohydrate storage and survival of a native and an introduced tree species in relation to light and defoliation.

Fraxinus uhdei (Wenz.) Lingelsh (tropical ash), a species introduced to Hawaii from Mexico, invades forests of the endemic tree Acacia koa A.Gray (koa). We examined physiological and morphological characteristics of koa and tropical ash to explore possible mechanisms that may facilitate invasion of koa forests by tropical ash. Seedlings of both species were grown in a greenhouse in three light treatments: 100% photosynthetic photon flux (PPF); 18% PPF; and 2% PPF inside the greenhouse. Light compensation point, maximum CO2 assimilation rate and dark respiration rate of seedlings differed significantly among light treatments, but were similar between species. A defoliation experiment indicated that tropical ash was better able to survive defoliation than koa, especially under high-light conditions. Tropical ash seedlings allocated more carbon (C) and nitrogen (N) to storage per unit PPF than koa seedlings. Total nonstructural carbohydrates were positively correlated with plant survival in both species. The patterns of C and N allocation associated with tropical ash seedlings favor their survival in high light, under intense herbivory and on sites where N availability is seasonal or highly variable. Variation in carbohydrate storage between koa and tropical ash greatly exceeded variation in photosynthetic performance at the leaf level.

Acacia↗

PubMed2004

Component and whole-system respiration fluxes in northern deciduous forests.

We measured component and whole-system respiration fluxes in northern hardwood (Acer saccharum Marsh., Tilia americana L., Fraxinus pennsylvanica Marsh.) and aspen (Populus tremuloides Michx.) forest stands in Price County, northern Wisconsin from 1999 through 2002. Measurements of soil, leaf and stem respiration, stem biomass, leaf area and biomass, and vertical profiles of leaf area were combined with biometric measurements to create site-specific respiration models and to estimate component and whole-system respiration fluxes. Hourly estimates of component respiration were based on site measurements of air, soil and stem temperature, leaf mass, sapwood volume and species composition. We also measured whole-system respiration from an above-canopy eddy flux tower. Measured soil respiration rates varied significantly among sites, but not consistently among dominant species (P < 0.05 and P > 0.1). Annual soil respiration ranged from 8.09 to 11.94 Mg C ha(-1) year(-1). Soil respiration varied linearly with temperature (P < 0.05), but not with soil water content (P > 0.1). Stem respiration rates per unit volume and per unit area differed significantly among species (P < 0.05). Stem respiration per unit volume of sapwood was highest in F. pennsylvanica (up to 300 micro mol m(3) s(-1)) and lowest in T. americana (22 micro mol m(3) s(-1)) when measured at peak summer temperatures (27 to 29 degrees C). In northern hardwood stands, south-side stem temperatures were higher and more variable than north-side temperatures during leaf-off periods, but were not different statistically during leaf-on periods. Cumulative annual stem respiration varied by year and species (P < 0.05) and averaged 1.59 Mg C ha(-1) year(-1). Leaf respiration rates varied significantly among species (P < 0.05). Respiration rates per unit leaf mass measured at 30 degrees C were highest for P. tremuloides (38.8 nmol g(-1) s(-1)), lowest for Ulmus rubra Muhlenb. (13.1 nmol g(-1) s(-1)) and intermediate and similar (30.2 nmol g(-1) s(-1)) for T. americana, F. pennsylvanica and Q. rubra. During the growing season, component respiration estimates were dominated by soil respiration, followed by leaf and then stem respiration. Summed component respiration averaged 11.86 Mg C ha(-1) year(-1). We found strong covariance between whole-ecosystem and summed component respiration measurements, but absolute rates and annual sums differed greatly.

Acer↗

PubMed2005

Element accumulation patterns of deciduous and evergreen tree seedlings on acid soils: implications for sensitivity to manganese toxicity.

Foliar nutrient imbalances, including the hyperaccumulation of manganese (Mn), are correlated with symptoms of declining health in sensitive tree species growing on acidic forest soils. The objectives of this study were to: (1) compare foliar nutrient accumulation patterns of six deciduous (sugar maple (Acer saccharum Marsh.), red maple (Acer rubrum L.), red oak (Quercus rubra L.), white oak (Quercus alba L.), black cherry (Prunus serotina Ehrh.) and white ash (Fraxinus americana L.)) and three evergreen (eastern hemlock (Tsuga canadensis L.), white pine (Pinus strobus L.) and white spruce (Picea glauca (Moench) Voss.)) tree species growing on acidic forest soils; and (2) examine how leaf phenology and other traits that distinguish evergreen and deciduous tree species influence foliar Mn accumulation rates and sensitivity to excess Mn. For the first objective, leaf samples of seedlings from five acidic, non-glaciated field sites on Pennsylvania's Allegheny Plateau were collected and analyzed for leaf element concentrations. In a second study, we examined growth and photosynthetic responses of seedlings exposed to excess Mn in sand culture. In field samples, Mn in deciduous foliage hyperaccumulated to concentrations more than twice as high as those found in evergreen needles. Among species, sugar maple was the most sensitive to excess Mn based on growth and photosynthetic measurements. Photosynthesis in red maple and red oak was also sensitive to excess Mn, whereas white oak, black cherry, white ash and the three evergreen species were tolerant of excess Mn. Among the nine species, relative rates of photosynthesis were negatively correlated with foliar Mn concentrations, suggesting that photosynthetic sensitivity to Mn is a function of its rate of accumulation in seedling foliage.

Acer↗