| experimental toxicology of pyrolysis and combustion hazards. | data are presented on the acute toxicity (mortality only) of the thermal degradation products of polymers obtained by two methods of degradation. one system utilized a slowly increasing temperature (5 degrees c/min) and gradual degradation of the polymer with the rats being exposed to degradation products as they were evolved. in this system the more toxic polymers included wool, polypropylene, poly(vinyl chloride), and urethane foam. the second system utilized conditions of rapid combustion and ... | 1975 | 1175552 |
| gastropod availability and habitat utilization by wapiti and white-tailed deer sympatric on range enzootic for meningeal worm. | gastropod occurrence and the utilization of habitat by sympatric populations of wapiti (cervus elephus) and white-tailed deer (odocoileus virginianus) on range enzootic for meningeal worm (parelaphostrongylus tenuis) were studied on cookson hills wildlife management area (wma) in eastern oklahoma. visual observations and fecal pellet group transect data indicated that wapiti spent the majority of their time in open fields and meadows where we recovered the least numbers of gastropods. although d ... | 1991 | 2023333 |
| effects of certain atmospheric pollutants (so2, no2 and co) on the soluble amino acids, molecular weight and antigenicity of some airborne pollen grains. | the pure pollen grains of red oak (quercus rubra), meadow fescue (festuca elatior) and chinese elm (ulmas pumila) were exposed to carbon monoxide (co), sulphur dioxide (so2) and nitrogen dioxide (no2). after exposure, the soluble free amino acids were determined from the extracts using two-dimensional thin layer chromatography, and the molecular weight of the extracts were determined by sds-gel electrophoresis (page). the results indicated that after contamination, both the amino acids and molec ... | 1986 | 2426043 |
| some physiological effects of temperature on artificially reared red oak borers. | | 1974 | 4443464 |
| interferon research. | two taxonomic errors appeared in the report "oak leaf quality declines in response to defoliation by gypsy moth larvae" by j. c. schultz and i. t. baldwin (9 july 1982, p. 149). in the first column on page 149, quercus rubrum should have been quercus rubra l., and in the first column on page 150, q. nigra should have been q. velutina lam. | 1983 | 6186028 |
| persistence of la crosse virus (california encephalitis serogroup) in north-central illinois. | la crosse (lac) virus was first isolated in illinois from a pool of 50 female aedes triseriatus mosquitoes collected in july 1976, in peoria heights. from 1978 through 1981, 27 strains (11 from males and 16 from females) of lac virus were recovered from 888 pools containing 22,021 adult a. triseriatus mosquitoes from the same study area. these mosquitoes had developed from larvae and pupae collected from 50 individually identified treeholes. of the 14 trees that yielded lac virus-positive mosqui ... | 1983 | 6824122 |
| red oak condensate: its apparent lack of cytotoxic and genotoxic effects as compared with three other wood-drying condensates. | a major activity of the lumber industry is the kiln-drying of wood. in order to ascertain whether wood-drying condensates pose a possible environmental hazard, the cytotoxicity and genotoxicity of these condensates in vitro, were tested using an assay validated using chinese hamster ovary (cho) cells and a known genotoxicant, mitomycin c. subsequently, the assay was developed for the human peripheral blood lymphocyte (hpbl) system, as it was felt that results derived from human cells would refle ... | 1995 | 8829893 |
| effects of tannins on digestion and detoxification activity in gray squirrels (sciurus carolinensis). | acorn tannins may affect food preferences and foraging strategies of squirrels through effects on acorn palatability and digestibility and squirrel physiology. captive eastern gray squirrels (sciurus carolinensis) were fed 100% red oak (quercus rubra) or white oak (quercus alba) acorn diets to determine effects on intake, digestion, and detoxification activity. red oak acorns had higher phenol and tannin levels, which may explain the lower dry matter intakes and apparent protein digestibilities ... | 1997 | 9231400 |
| state and phase transition behaviors of quercus rubra seed axes and cotyledonary tissues: relevance to the desiccation sensitivity and cryopreservation of recalcitrant seeds | freezing and melting transitions of cellular water in embryonic axes and cotyledonary tissues of recalcitrant quercus rubra (red oak) seeds were compared under slow and rapid cooling conditions. the relevance of desiccation sensitivity (critical water content) and state/phase transition behaviors to cryopreservation was examined. under a slow to intermediate cooling condition (</=10 degrees c min(-1)), unfrozen water content in the tissues decreased to less than the critical water content, resul ... | 1999 | 10413579 |
| inhibition of seedling survival under rhododendron maximum (ericaceae): could allelopathy be a cause? | in the southern appalachian mountains a subcanopy species, rhododendron maximum, inhibits the establishment and survival of canopy tree seedlings. one of the mechanisms by which seedlings could be inhibited is an allelopathic effect of decomposing litter or leachate from the canopy of r. maximum (r.m.) on seed germination, root elongation, or mycorrhizal colonization. the potential for allelopathy by r.m. was tested with two bioassay species (lettuce and cress), with seeds from four native tree ... | 1999 | 10562250 |
| intra-ring variability of cr, as, cd, and pb in red oak revealed by secondary ion mass spectrometry: implications for environmental biomonitoring. | reconstructing the history of ambient levels of metals by using tree-ring chemistry is controversial. this controversy can be resolved in part through the use of selective microanalysis of individual wood cells. using a combination of instrumental neutron activation analysis and secondary ion mass spectrometry, we have observed systematic inhomogeneity in the abundance of toxic metals (cr, as, cd, and pb) within annual growth rings of quercus rubra (red oak) and have characterized individual xyl ... | 1999 | 10588757 |
| execution of the auxin replacement apical dominance experiment in temperate woody species. | the classic thimann-skoog or auxin replacement apical dominance test of exogenous auxin repression of lateral bud outgrowth was successfully executed in both seedlings and older trees of white ash, green ash, and red oak under the following conditions: (1) decapitation of a twig apex and auxin replacement were carried out during spring flush, (2) the decapitation was in the previous season's overwintered wood, and (3) the point of decapitation was below the upper large irrepressible lateral buds ... | 2000 | 10675304 |
| effect of variety, processing, and storage on the flavonoid glycoside content and composition of lettuce and endive. | eight varieties of lettuce (lactuca sativum) and three varieties of endive (cichorium endivia) were analyzed for flavonoid composition and content. total flavonoid contents, expressed as units of aglycon for fresh material, were in the ranges of 0.3-229 microg/g for lettuce and 44-248 microg/g for endive. five quercetin conjugates [quercetin 3-o-galactoside, quercetin 3-o-glucoside, quercetin 3-o-glucuronide, quercetin 3-o-(6-o-malonyl)glucoside, and quercetin 3-o-rhamnoside] and luteolin 7-o-gl ... | 2000 | 10995297 |
| analysis of oak tannins by liquid chromatography-electrospray ionisation mass spectrometry. | extractable tannins were analysed by liquid chromatography-electrospray ionisation mass spectrometry in two oak species, north american white oak (quercus alba) and european red oak (quercus robur). they mainly included various glucose gallic and ellagic acid esters. the structures were partially determined, and they included grandinin/roburin e, castalagin/vescalagin, gallic acid, valoneic acid bilactone, monogalloyl glucose, digalloyl glucose, trigalloyl glucose, ellagic acid rhamnose, quercit ... | 2000 | 10999626 |
| substitutes for human cadaveric bone in maxillofacial rigid fixation research. | various materials have been used as human bone substitutes in rigid fixation research. we hypothesize that these substitutes behave differently than human cadaveric bone in maxillofacial research. | 2000 | 11077379 |
| dielectric relaxation of water and water-plasticized biomolecules in relation to cellular water organization, cytoplasmic viscosity, and desiccation tolerance in recalcitrant seed tissues. | to understand the relationship between the organization of cellular water, molecular interactions, and desiccation tolerance, dielectric behaviors of water and water-plasticized biomolecules in red oak (quercus rubra) seeds were studied during dehydration. the thermally stimulated current study showed three dielectric dispersions: (a) the relaxation of loosely-bound water and small polar groups, (b) the relaxation of tightly-bound water, carbohydrate chains, large polar groups of macromolecules, ... | 2000 | 11080297 |
| hardwood seeding root and nutrient parameters for a model of nutrient uptake. | use of mechanistic models is an increasingly accepted way to evaluate complex processes. the barber-cushman model provides a means to simulate nutrient uptake once information on root system characteristics, nutrient uptake, and soil nutrient supply are developed. objectives of this study were to determine during a growing season: (i) root growth for 1-yr-old black cherry (prunus serotina ehrh.), northern red oak (quercus rubra l.), and red maple (acer rubrum l.) seedlings; (ii) net plant increa ... | 2001 | 11285903 |
| red oak. | | 2001 | 11289338 |
| nutritional ecology of the formosan subterranean termite (isoptera: rhinotermitidae): feeding response to commercial wood species. | the feeding preferences of the formosan subterranean termite, coptotermes formosanus shiraki, were tested in three separate experiments on 28 different wood species. experiment 1 was a multiple-choice test designed to test relative preferences among 24 wood species commercially available in new orleans, la. experiment 2 was a similar study designed to test relative preferences among 21 wood species shown or reported to be unpalatable to the formosan subterranean termite. experiment 3 was a no-ch ... | 2001 | 11332848 |
| ice storm damage and early recovery in an old-growth forest. | we quantified the damage caused by a major ice storm to individual trees in two 1-ha permanent plots located at mont st. hilaire in southwestern québec, canada. the storm, which occurred in january 1998, is the worst on record in eastern north america; glaze ice on the order of 80-100 mm accumulated at our study site. all but 3% of the trees (dbh > or = 10 cm) lost at least some crown branches, and 35% lost more than half their crown. damage to trees increased in the order: tsuga canadensis, bet ... | 2001 | 11339708 |
| light- and cold-stress effects on the greening process in epicotyls and young stems of red oak (quercus rubra) seedlings. | protochlorophyllide (pchlide) and protochlorophyll (pchl) were found in epicotyls of 14-day-old dark-germinated seedlings and in 100-day-old dark-grown stems of red oak (quercus rubra l.). fluorescence spectroscopy measurements of epicotyls at 77 k showed that the majority of pchlide and pchl is present as a shorter wavelength-emitting monomer with a fluorescence emission maximum at 629-631 nm. a small amount of a monomeric form emitting at 635-636 nm was also present. minor amounts of pchlide w ... | 2001 | 11359713 |
| responses of leaf respiration to temperature and leaf characteristics in three deciduous tree species vary with site water availability. | we measured responses of leaf respiration to temperature and leaf characteristics in three deciduous tree species (quercus rubra l., quercus prinus l. and acer rubrum l.) at two sites differing in water availability within a single catchment in the black rock forest, new york. the response of respiration to temperature differed significantly among the species. acer rubrum displayed the smallest increase in respiration with increasing temperature. corresponding q(10) values ranged from 1.5 in a. ... | 2001 | 11390301 |
| chemical characterization of fine particle emissions from fireplace combustion of woods grown in the northeastern united states. | a series of source tests was conducted to determine the chemical composition of fine particle emissions from the fireplace combustion of six species of woods grown in the northeastern united states: red maple, northern red oak, paper birch, eastern white pine, eastern hemlock, and balsam fir. results include fine particle emission rates for total mass, organic and elemental carbon, ionic species, elemental species including potassium, and over 250 specific organic compounds. the data are intende ... | 2001 | 11452590 |
| effects of nutrient supplements on biological efficiency, quality and crop cycle time of maitake (grifola frondosa). | the effects of various combinations of wheat bran, rye and millet (at 20% and 30% of total dry substrate wt) on crop cycle time, biological efficiency (be) and mushroom quality were evaluated for a commercially used isolate of grifola frondosa (maitake). supplements were combined with a basal ingredient of mixed oak (primarily red oak) sawdust, and the resulting mixture was pasteurized, cooled, inoculated and bagged with an autoclaving mixer. times to mushroom primordial formation and mushroom h ... | 2001 | 11693937 |
| alteration of foliar flavonoid chemistry induced by enhanced uv-b radiation in field-grown pinus ponderosa, quercus rubra and pseudotsuga menziesii. | chromatographic analyses of foliage from several tree species illustrate the species-specific effects of uv-b radiation on both quantity and composition of foliar flavonoids. pinus ponderosa, quercus rubra and pseudotsuga menziesii were field-grown under modulated ambient (1x) and enhanced (2x) biologically effective uv-b radiation. foliage was harvested seasonally over a 3-year period, extracted, purified and the flavonoid fraction applied to a mu bondapak/c(18) column hplc system sampling at 2 ... | 2002 | 11897512 |
| energy investment in leaves of red maple and co-occurring oaks within a forested watershed. | despite its recent expansion in eastern us forests, red maple (acer rubrum l.) generally exhibits a low leaf photosynthetic rate, leaf mass per unit area (lma) and leaf nitrogen concentration ([n]) relative to co-occurring oaks (quercus spp.). to evaluate these differences from the perspective of leaf energy investment, we compared leaf construction cost (cc) and leaf maintenance cost (mc) with leaf photosynthetic rate at saturating photon flux density and ambient co2 partial pressure (amax) in ... | 2002 | 12184975 |
| the hydraulic conductance of the angiosperm leaf lamina: a comparison of three measurement methods. | a comparison was made of three methods for measuring the leaf lamina hydraulic conductance (k(lamina)) for detached mature leaves of six woody temperate angiosperm species. the high-pressure method, the evaporative flux method and the vacuum pump method involve, respectively, pushing, evaporating and pulling water out of the lamina while determining the flow rate into the petiole and the water potential drop across the leaf. tests were made of whether the high-pressure method and vacuum pump met ... | 2002 | 12379784 |
| semiquinone and ascorbyl radicals in the gut fluids of caterpillars measured with epr spectrometry. | the biological activity of phenolic compounds ingested by caterpillars is commonly believed to result from their oxidation, although the products of oxidation have been well-characterized in only a few cases. the initial oxidation products of phenols (semiquinone or phenoxyl radicals) can be measured with electron paramagnetic resonance (epr) spectrometry. in this study semiquinone radicals formed from tannic acid and gallic acid in the gut fluids of two species of caterpillars were measured. in ... | 2003 | 12459207 |
| analysing branching pattern in plantations of young red oak trees (quercus rubra l., fagaceae). | branching patterns of the growth units of monocyclic or bicyclic annual shoots on the main axis of 5-year-old red oaks were studied in a plantation in south-western france. for each growth unit, the production of axillary structures associated with each node was described in the form of a sequence. for a given category of growth units, homogeneous zones (i.e. zones in which composition in terms of type of axillary production does not change substantially) were identified on such sequences using ... | 2003 | 12588728 |
| does canopy position affect wood specific gravity in temperate forest trees? | the radial increases in wood specific gravity known in many tree species have been interpreted as providing mechanical support in response to the stresses associated with wind loading. this interpretation leads to the hypothesis that individuals reaching the canopy should (1) be more likely to have radial increases in specific gravity and (2) exhibit greater increases than individuals in the subcanopy. wood specific gravity was determined for three species of forest trees (acer rubrum, fagus gra ... | 2003 | 12646497 |
| kinetics of leaf temperature fluctuation affect isoprene emission from red oak (quercus rubra) leaves. | because the rate of isoprene (2-methyl-1,3-butadiene) emission from plants is highly temperature-dependent, we investigated natural fluctuations in leaf temperature and effects of rapid temperature change on isoprene emission of red oak (quercus rubra l.) leaves at the top of the canopy at harvard forest. throughout the day, leaves often reached temperatures as much as 15 degrees c above air temperature. the highest temperatures were reached for only a few seconds at a time. we compared isoprene ... | 1999 | 12651303 |
| controls on mass loss and nitrogen dynamics of oak leaf litter along an urban-rural land-use gradient. | using reciprocal leaf litter transplants, we investigated the effects of contrasting environments (urban vs. rural) and intraspecific variations in oak leaf litter quality on mass loss rates and nitrogen (n) dynamics along an urban-rural gradient in the new york city metropolitan area. differences in earthworm abundances and temperature had previously been documented in the stands along this gradient. red oak leaf litter was collected and returned to its original source stand as native litter to ... | 2003 | 12698351 |
| molecular differentiation and diversity among the california red oaks (fagaceae; quercus section lobatae). | a recent epidemic of phytopthora (sudden oak death) in coastal woodlands of california is causing severe mortality in some oak species belonging to the red oak (lobatae) group. to predict the risks of spread of this disease, an understanding of the relationships among california's red oak species and of their population genetic structure is needed. we focus here on relationships among the four species of red oak. whereas morphological distinction of quercus wislizeni and quercus parvula can pose ... | 2003 | 12761621 |
| nitrogen export from a watershed subjected to partial salvage logging. | logging has been shown to induce nitrogen (n) leaching. we hypothesized that logging a watershed that previously exhibited forest decline symptoms would place additional stress on the ecosystem and result in greater n loss, compared to harvesting vigorous forests. we conducted a 10-year (1988 to 1998) assessment of n export from the baldwin creek watershed in southwestern pennsylvania that was partially clearcut to salvage dead and dying northern red oak. n export from the watershed increased si ... | 2001 | 12805802 |
| antioxidants in the midgut fluids of a tannin-tolerant and a tannin-sensitive caterpillar: effects of seasonal changes in tree leaves. | the seasonal decline in foliar nutritional quality in deciduous trees also effects the availability of essential micronutrients, such as ascorbate and alpha-tocopherol, to herbivorous insects. this study first examined whether there are consistent patterns of seasonal change in antioxidant concentrations in deciduous tree leaves. alpha-tocopherol concentrations increased substantially through time in late summer in sugar maple (acer saccharum), red oak (quercus rubra), and trembling aspen (popul ... | 2003 | 12857024 |
| rapid temperature acclimation of leaf respiration rates in quercus alba and quercus rubra. | we conducted controlled (chamber) and natural (field) environment experiments on the acclimation of respiration in quercus alba l. and quercus rubra l. three-year-old louisiana, indiana and wisconsin populations of q. alba were placed in growth chambers and exposed to alternating 5-week periods of cool (20 degrees c mean) and warm (26 degrees c mean) temperatures. we measured respiration rates on fully expanded leaves immediately before and approximately every 2 days after a switch in mean tempe ... | 2003 | 12952783 |
| mandibulotomy fixation: a laboratory analysis. | mandibulotomy is an access osteotomy technique associated with significant complications. critical evaluation of available fixation systems is required to aid in the selection of the most stable fixation method. this study was designed to provide data on the stability of traditionally used plating configurations and a low-profile 2.0-mm locking plate (mandibular locking plate, synthes mlp; synthes maxillofacial, paoli, pa). | 2003 | 14613086 |
| acclimation of shade-developed leaves on saplings exposed to late-season canopy gaps. | we hypothesized that photoinhibition of shade-developed leaves of deciduous hardwood saplings would limit their ability to acclimate photosynthetically to increased irradiance, and we predicted that shade-tolerant sugar maple (acer saccharum marsh.) would be more susceptible to photoinhibition than intermediately shade-tolerant red oak (quercus rubra l.). after four weeks in a canopy gap, photosynthetic rates of shade-developed leaves of both species had increased in response to the increase in ... | 1997 | 14759845 |
| carbon partitioning and allocation in northern red oak seedlings and mature trees in response to ozone. | northern red oak (quercus rubra l.) seedlings and trees differ in their response to ozone. previous work reported reductions in net photosynthesis, carboxylation efficiency and quantum yield of mature tree leaves, whereas seedling processes were unaffected by the same ozone exposure. to further characterize differences in ozone response between seedlings and mature trees, we examined carbon partitioning and allocation in 32-year-old trees and 4-year-old seedlings of northern red oak after exposu ... | 1996 | 14871676 |
| requirements for in vitro rooting of quercus robur and q. rubra shoots derived from mature trees. | stabilized shoot cultures initiated from crown material of six adult quercus robur l. trees and from basal epicormic shoots of a quercus rubra l. tree showed good in vitro rooting capacity. an initial five-day dark period generally improved the rooting response but was detrimental to plantlet quality. there were clonal differences in rooting capacity. the concentration and exposure time of the indolebutyric acid (iba) treatment were critical for root induction. in both species, best rooting effi ... | 1996 | 14871689 |
| field measurements of isoprene emission from trees in response to temperature and light. | the atmospheric hydrocarbon budget is important for predicting ozone episodes and the effects of pollution mitigation strategies. isoprene emission from plants is an important part of the atmospheric hydrocarbon budget. we measured isoprene emission capacity at the bottom, middle, and top of the canopies of a white oak (quercus alba l.) tree and a red oak (quercus rubra l.) tree growing adjacent to a tower in the duke university forest. leaves at the top of the white oak tree canopy had a three- ... | 1996 | 14871703 |
| effects of elevated co(2) and light availability on the photosynthetic light response of trees of contrasting shade tolerance. | photosynthetic light response curves (a/ppfd), leaf n concentration and content, and relative leaf absorbance (alpha(r)) were measured in 1-year-old seedlings of shade-intolerant betula papyrifera marsh., moderately shade-tolerant quercus rubra l. and shade-tolerant acer rubrum l. seedlings were grown in full sun or 26% of full sun (shade) and in ambient (350 ppm) or elevated (714 ppm) co(2) for 80 days. in the shade treatments, 80% of the daily ppfd on cloud-free days was provided by two 30-min ... | 1996 | 14871736 |
| hay-scented fern (dennstaedtia punctilobula (michx.) moore) interference with growth of northern red oak (quercus rubra l.) seedlings. | we assessed the impacts of hay-scented fern (dennstaedtia punctilobula (michx.) moore) and subsoil liming (cao amendments) on root and shoot growth of greenhouse-grown, first-year, northern red oak (quercus rubra l.) seedlings. red oak seedlings and ferns were grown in reconstructed soil profiles of four common pennsylvanian forest soils. when grown in the presence of hay-scented ferns, with or without subsoil liming, red oak seedlings had significantly reduced height growth, and foliar, stem an ... | 1996 | 14871785 |
| changes in respiration and chemical content during autumnal senescence of populus tremuloides and quercus rubra leaves. | changes in respiration rate, chemical content and chemical concentration were measured in leaves of field-grown populus tremuloides michx. and quercus rubra l. trees throughout the growing season and autumnal senescence. chlorophyll, soluble sugar, n, p, k and mg contents and concentrations all declined during leaf senescence, whereas ca content and concentration increased. leaf dry mass per area declined 24 and 35% in p. tremuloides and q. rubra, respectively, during senescence. in leaves of bo ... | 1995 | 14965995 |
| frost tolerance and bud dormancy of container-grown yellow birch, red oak and sugar maple seedlings. | container-grown seedlings of red oak (quercus rubra l.), sugar maple (acer saccharum marsh.) and yellow birch (betula alleghaniensis britton) in their first year of growth were overwintered outdoors. tolerance of roots and stems to freezing was compared from late summer to the following spring. mitotic activity in the apical bud was related more closely to air temperature than to bud dormancy as defined by days to bud break. in all species, stem hardening was observed before days to bud break re ... | 1994 | 14967606 |
| seasonal patterns of light-saturated photosynthesis and leaf conductance for mature and seedling quercus rubra l. foliage: differential sensitivity to ozone exposure. | extrapolation of the effects of ozone on seedlings to large trees and forest stands is a common objective of current assessment activities, but few studies have examined whether seedlings are useful surrogates for understanding how mature trees respond to ozone. this two-year study utilized a replicated open-top chamber facility to test the effects of subambient, ambient and twice ambient ozone concentrations on light-saturated net photosynthesis (p(max)) and leaf conductance (g(l)) of leaves fr ... | 1994 | 14967609 |
| shade, leaf growth and crown development of quercus rubra, quercus velutina, prunus serotina and acer rubrum seedlings. | the study was conducted in an open field to determine the optimum irradiance for establishment and growth of two oak species and two major associated woody species. half-sib seedlings of black cherry (prunus serotina ehrh.), red maple (acer rubrum l.), northern red oak (quercus rubra l.) and black oak (q. velutina lam.) were grown for two years under shade-cloth tents. eight shade treatments (94, 70, 57, 45, 37, 27, 20 and 8% of full sunlight) with three replications each were used. measurements ... | 1994 | 14967644 |
| genotypic and phenotypic variation as stress adaptations in temperate tree species: a review of several case studies. | species that occupy large geographic ranges or a variety of habitats within a limited area deal with contrasting environmental conditions by genotypic and phenotypic variation. my students and i have studied these forms of ecophysiological variation in temperate tree species in eastern north america by means of a series of field and greenhouse experiments, including controlled studies with cercis canadensis l., fraxinus pennsylvanica marsh., acer rubrum l., prunus serotina ehrh. and quercus rubr ... | 1994 | 14967652 |
| canopy dynamics and aboveground production of five tree species with different leaf longevities. | canopy dynamics and aboveground net primary production (anpp) were studied in replicated monospecific and dual-species plantations comprised of species with different leaf longevities. in the monospecific plantations, leaf longevity averaged 5, 6, 36, 46 and 66 months for quercus rubra l., larix decidua miller, pinus strobus l., pinus resinosa ait. and picea abies (l.) karst., respectively. specific leaf area, maximum net photosynthesis per unit mass (a/mass), leaf n per unit mass (n(leaf)/mass) ... | 1993 | 14969905 |
| carbon and nitrogen assimilation in red oaks (quercus rubra l.) subject to defoliation and nitrogen stress. | to examine how rates of net photosynthesis and n uptake of red oak seedlings respond to defoliation under contrasting conditions of n availability, nitrogen-deficient plants were grown in sand culture and subjected to partial defoliation and increased n availability under low light conditions. both photosynthesis and n uptake rates were measured regularly before and after the treatments. defoliation resulted in elevated rates of net photosynthesis in both low-n and high-n trees, but the high-n t ... | 1993 | 14969916 |
| in vitro shoot proliferation determined by explant orientation of juvenile and mature quercus rubra l. | shoot cultures of quercus rubra (l.) were established from both juvenile and adult plant material. initial explants from epicormic shoots formed on the basal zone of the trunks had a greater capacity for in vitro establishment than explants from crown branches. the growth of vigorous axillary shoots was obtained by culturing decapitated shoots horizontally on woody plant medium supplemented with 0.2 mg l(-1) of 6-benzylaminopurine. after 3 weeks of culture the shoots were transferred to fresh me ... | 1993 | 14969922 |
| variation in seedling hydraulic architecture as a function of species and environment. | northern red oak (quercus rubra l.) and yellow-poplar (liriodendron tulipifera l.) were grown for two years in full sunlight (unshaded) or 20% of full sunlight (shaded) under either well-watered or drought conditions. there was a close association between evaporative flux (in situ) and leaf-specific conductivity (lsc) in stem segments of both species. shaded, drought-stressed seedlings of both species had significantly reduced leaf area, evaporative flux, volume flow rate in xylem, flow velocity ... | 1993 | 14969933 |
| the impact of water and nutrient deficiencies on the growth, gas exchange and water relations of red oak and chestnut oak. | red oak (quercus rubra), a mesic species, and chestnut oak (quercus prinus), a xeric species, were grown in a greenhouse with and without fertilizer (f+ and f-, respectively) and subjected to a 10-week drydown (w-) or kept well watered (w+). in both species, fertilized seedlings exhibited greater reductions in mean net photosynthesis (a), leaf conductance (g(wv)), leaf water potential (psi(leaf)) and water use efficiency (wue) during the drydown than unfertilized seedlings. in the w- treatments, ... | 1992 | 14969951 |
| loss of hydraulic conductivity due to water stress in intact juveniles of quercus rubra and populus deltoides. | despite many studies of the percent loss of hydraulic conductivity in excised branches, there is doubt as to whether cutting stems in air introduces unnatural embolism into the xylem at the cut surface. to address this question, hydraulic conductivity was measured in seedlings of northern red oak (quercus rubra l.) and rooted scions of eastern cottonwood (populus deltoides bartr. ex marsh.) that had been droughted in pots. results indicate that in situ dehydration produced a very similar vulnera ... | 1992 | 14969978 |
| sensitivity of red oak (quercus rubra l.) and american beech (fagus grandifolia ehrh.) seedlings to sodium salts in solution culture. | sodium salt sensitivity of red oak (quercus rubra l.) and american beech (fagus grandifolia ehrh.) was evaluated in solution culture. both species showed symptoms of salt injury when grown in the presence of less than 10 mm na. in red oak, leaf symptoms first appeared at a sodium concentration of 6.0 mm and leaf weight was significantly reduced at 7.5 mm na. leaf, stem and root dry weights of american beech were significantly reduced in the presence of 4.0 mm sodium. in both species, browning of ... | 1988 | 14972826 |
| distribution and metabolism of current photosynthate by single-flush northern red oak seedlings. | carbon distribution and metabolism by northern red oak seedlings (quercus rubra l.) were followed for 72 h after a 30-min photosynthetic exposure to (14)co(2). approximately 50% of the assimilated carbon was lost during this time, presumably through respiration. most of the (14)c recovered in the plant remained in the source leaf. most of the exported (14)c was found in stems and especially roots. position of the source leaf did not affect distribution of translocated (14)c; however, upper sourc ... | 1990 | 14972906 |
| gas exchange in quercus rubra (northern red oak) during a drought: analysis of relations among photosynthesis, transpiration, and leaf conductance. | development of water stress in leaves of mature quercus rubra l. caused a marked midday depression in photosynthesis (a) and transpiration (e). at external co(2) partial pressures of 100-110 pa, a constant temperature of 30 degrees c and a constant photosynthetic photon flux density of about 1000 micromol m(-2) s(-1), a was 8 micromol m(-2) at low leaf water potentials (-1.5 to -2.0 mpa), whereas it was 20 micromol m(-2) s(-1) in non-stressed leaves (-1.0 mpa). at lower external co(2) partial pr ... | 1990 | 14972919 |
| adaptations and responses to drought in quercus species of north america. | most north american oaks (quercus spp.) are adapted to drought-prone sites by an ability either to avoid, or to tolerate, water stress, or both. generally, they have deep-penetrating root systems, enabling them to maintain relatively high predawn water potentials during drought. oaks have thick leaves and some have relatively small stomata, both characteristics that favor high water use efficiency. however, some species, from warm regions, have large stomatal pores. the rapid evaporative cooling ... | 1990 | 14972920 |
| interactive effects of resource availabilities and defoliation on photosynthesis, growth, and mortality of red oak seedlings. | responses of forest trees to defoliation by insects such as gypsy moth vary greatly from site to site and from individual to individual. to determine whether some of this variation could be explained by variation in other stress factors, red oak (quercus rubra l.) seedlings were exposed to low and high light, water, mineral nutrient, and defoliation treatments, in a complete factorial design in a greenhouse. significant interactions were observed among factors for photosynthesis, growth, and mor ... | 1990 | 14972922 |
| xylem dysfunction in quercus: vessel sizes, tyloses, cavitation and seasonal changes in embolism. | the seasonal progression of xylem dysfunction from tyloses and embolism induced both by cavitation and frost was studied in quercus rubra l. and quercus alba l. branches. vessel lengths and diameters were measured in current-year rings of branches of various ages. vessels in current-year shoots are about the same size as those in many diffuse porous trees, but vessels in older branches are two to six times larger in diameter and typically more than 10 times longer. large quercus vessels were mor ... | 1990 | 14972931 |
| a morphological index of quercus seedling ontogeny for use in studies of physiology and growth. | attempts to relate plant metabolic activity with developmental stage are often hindered by lack of an appropriate developmental index. existing indices of morphological development are unsuitable for use with plants having a semideterminate, recurrently flushing pattern of growth as displayed by quercus seedlings. we propose the following morphological index (qmi) to define the stages of quercus seedling ontogeny: (1) radicle emergence; (2) epicotyl emergence from the soil; and (for each flush) ... | 1986 | 14975860 |
| increased mortality of gypsy moth lymantria dispar (l.) (lepidoptera: lymantriidae) exposed to gypsy moth nuclear polyhedrosis virus in combination with the phenolic gycoside salicin. | second instar gypsy moth, lymantria dispar (l.) (lepidoptera: lymantriidae), larvae suffered significantly greater mortality from aerially applied gypsy moth nuclear polyhedrosis virus (gypchek) when the virus was consumed on quaking aspen, populus tremuloides michx., versus red oak, quercus spp. l., foliage. laboratory assays in which various doses of gypchek and salicin (a phenolic glycoside present in aspen foliage) were tested in combination demonstrated that salicin significantly increased ... | 2003 | 14977101 |
| hydraulic analysis of water flow through leaves of sugar maple and red oak. | leaves constitute a substantial fraction of the total resistance to water flow through plants. a key question is how hydraulic resistance within the leaf is distributed among petiole, major veins, minor veins, and the pathways downstream of the veins. we partitioned the leaf hydraulic resistance (r(leaf)) for sugar maple (acer saccharum) and red oak (quercus rubra) by measuring the resistance to water flow through leaves before and after cutting specific vein orders. simulations using an electro ... | 2004 | 15064368 |
| selection and dispersal in a multispecies oak hybrid zone. | the four western north american red oak species (quercus wislizeni, q. parvula, q. agrifolia, and q. kelloggii) are known to produce hybrid products in all interspecific combinations. however, it is unknown whether hybrids are transitory resulting from interspecific gene flow or whether they are maintained through extrinsic selection. here, we examine cryptic hybrid structure in q. wislizeni through a broad region including contact and isolation from three other western north american red oaks u ... | 2004 | 15068344 |
| growth and nutrition of quercus rubra l. seedlings and mature trees after three seasons of ozone exposure. | seedling growth and nutritional status have been shown to be sensitive to ozone, but the influence of multi-season ozone exposure on mature tree growth and nutrition has not been examined. to determine if seedlings and mature trees were similarly affected by ozone exposure, growth and nutrient concentrations in northern red oak (quercus rubra l.) 4-year-old seedlings and 32-year-old mature trees were examined after treatment with subambient, ambient and twice ambient concentrations of ozone for ... | 1996 | 15091424 |
| does (k+mg+ca+p) fertilization lead to recovery of tree health in a nitrogen stressed quercus rubra l. stand? | in the netherlands atmospheric deposition of nitrogen compounds to forest ecosystems has been very high for some decades and has led to severe nutritional imbalances in soils as well as in trees. at this moment legislation is not fully in effect with respect to lowering emission/deposition fluxes, particularly of nitrogen. the trees suffer mainly from severe magnesium, potassium and calcium and sometimes phosphorus deficiencies. in this study it was investigated whether fertilization with potass ... | 1994 | 15091660 |
| growth and physiology of northern red oak: preliminary comparisons of mature tree and seedling responses to ozone. | considerable progress has been made during the past decade in the development of mechanistic models that allow complex chemical, physical, and biological processes to be evaluated in the global change context. however, quantitative predictions of the response of individual trees, stands, and forest ecosystems to pollutants and climatic variables require extrapolation of existing data sets, derived largely from seedling studies, to increasing levels of complexity with little or no understanding o ... | 1994 | 15091764 |
| height growth of northern red oak in relation to site and atmospheric deposition in pennsylvania. | a forest tree growth-response to atmospheric deposition is expected to arise indirectly through soil chemical changes and would probably be observable only in the long term. we examined this hypothesis by evaluating the relationship between periodic height growth of mature northern red oak (quercus rubra l.) trees and soil, physiography and atmospheric sulfate deposition along a 170-km west-to-east gradient of decreasing sulfate deposition in north central pennsylvania, usa. height increments fo ... | 1993 | 15091852 |
| responses of plants to simulated saline drift as affected by species and conditions of exposure. | in exposures to simulated saline drift generated from a 0.6% (w/w) chloride (cl)-solution, under controlled environmental conditions, the median effective doses for the occurrence of any salt-induced foliar injury (expressed as microgcl cm(-2) deposited in six hours) were: 2.9 for canada hemlock (tsuga canadensis [l.] carr.); 10.3 for white flowering dogwood (cornus florida l.); 43.5 for potato (solanum tubersum l. cv superior); 44.2 for northern red oak (quercus rubra l.); 65.1 for sweet corn ( ... | 1991 | 15092146 |
| environmental control of stomatal conductance in forest trees of the great smoky mountains national park. | to determine if stomatal conductance (g(s)) of forest trees could be predicted from measures of leaf microclimate, diurnal variability in in situ g(s) was measured in black cherry (prunus serotina), red maple (acer rubrum), and northern red oak (quercus rubra). relative to overstory trees, understory saplings exhibited little diurnal variability in g(s) and ozone uptake. depending on species and site, up to 30% of diurnal and seasonal variation in g(s )of overstory trees was explained by photosy ... | 2000 | 15092837 |
| phylogenetic overdispersion in floridian oak communities. | closely related species that occur together in communities and experience similar environmental conditions are likely to share phenotypic traits because of the process of environmental filtering. at the same time, species that are too similar are unlikely to co-occur because of competitive exclusion. in an effort to explain the coexistence of 17 oak species within forest communities in north central florida, we examined correlations between the phylogenetic relatedness of oak species, their degr ... | 2004 | 15266381 |
| effect of a lignin-degrading fungus on feeding preferences of formosan subterranean termite (isoptera: rhinotermitidae) for different commercial lumber. | the feeding preferences of the formosan subterranean termite, coptotermes formosanus shiraki, for commercial lumber alaska yellow cedar, chamaecyparis nootkatensis (d. don) spach; yellow birch, betula alleghaniensis britton; northern red oak, quercus rubra l.; redwood, sequoia sempervirers (d. don) endl; and spruce (picea spp.) were examined to determine whether the presence of the lignin-degrading basidiomycete marasmiellus troyanus (murrill) singer could alter the relative preference of termit ... | 2004 | 15279287 |
| differential activity of peroxidase isozymes in response to wounding, gypsy moth, and plant hormones in northern red oak (quercus rubra l.). | we measured total peroxidase activity and the activities of peroxidase isoforms in leaves of red oak (quercus rubra l.) seedlings exposed to wounding and plant hormones in the greenhouse. activity of specific peroxidase isoforms was induced differentially by gypsy moth wounding, mechanical wounding, and the wound-associated plant hormone jasmonic acid. activity of one isoform was enhanced modestly by treatment with salicylate. a study of peroxidase activity in naturally occurring galls elicited ... | 2004 | 15503525 |
| environmental controls on sap flow in a northern hardwood forest. | our objective was to gain a detailed understanding of how photosynthetically active radiation (par), vapor pressure deficit (d) and soil water interact to control transpiration in the dominant canopy species of a mixed hardwood forest in northern lower michigan. an improved understanding of how these environmental factors affect whole-tree water use in unmanaged ecosystems is necessary in assessing the consequences of climate change on the terrestrial water cycle. we used continuously heated sap ... | 2005 | 15519983 |
| 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 ... | 2005 | 15519989 |
| microbial community structure and oxidative enzyme activity in nitrogen-amended north temperate forest soils. | large regions of temperate forest are subject to elevated atmospheric nitrogen (n) deposition which can affect soil organic matter dynamics by altering mass loss rates, soil respiration, and dissolved organic matter production. at present there is no general model that links these responses to changes in the organization and operation of microbial decomposer communities. toward that end, we studied the response of litter and soil microbial communities to high levels of n amendment (30 and 80 kg ... | 2004 | 15546042 |
| fungal degradation of wood: initial proteomic analysis of extracellular proteins of phanerochaete chrysosporium grown on oak substrate. | two-dimensional (2-d) gel electrophoresis was used to separate the extracellular proteins produced by the white-rot fungus phanerochaete chrysosporium. solid-substrate cultures grown on red oak wood chips yielded extracellular protein preparations which were not suitable for 2-d gel analysis. however, pre-washing the wood chips with water helped decrease the amount of brown material which caused smearing on the acidic side of the isoelectric focusing gel. the 2-d gels from these wood-grown cultu ... | 2005 | 15551134 |
| chloroplast dna variation of quercus rubra l. in north america and comparison with other fagaceae. | quercus rubra is one of the most important timber and ornamental tree species from eastern north america. it is a widespread species growing under variable ecological conditions. chloroplast dna variation was studied by pcr-rflp (polymerase chain reaction-restriction fragment length polymorphism) in 290 individuals from 66 populations sampled throughout the natural range. a total of 12 haplotypes were detected, with one found in 75% of the trees. population differentiation is relatively low (g(s ... | 2005 | 15660942 |
| diurnal and seasonal variations in leaf hydraulic conductance in evergreen and deciduous trees. | we studied changes in the hydraulic conductance of leaves (k(leaf)) between dawn and dusk during the growth period (july) and at midday at the beginning of autumn in four tree species. the main objectives of the study were to check the extent of diurnal and seasonal changes in k(leaf) and the relationships between k(leaf), irradiance and leaf gas exchange. two evergreen (aleurites moluccana and persea americana) and two deciduous trees (platanus orientalis and quercus rubra) were studied. leaf h ... | 2005 | 15687099 |
| does predation contribute to tree diversity? | seed and seedling predation may differentially affect competitively superior tree species to increase the relative recruitment success of poor competitors and contribute to the coexistence of tree species. we examined the effect of seed and seedling predation on the seedling recruitment of three tree species, acer rubrum (red maple), liriodendron tulipifera (yellow poplar), and quercus rubra (northern red oak), over three years by manipulating seed and seedling exposure to predators under contra ... | 2005 | 15719246 |
| hyperdiversity of ectomycorrhizal fungus assemblages on oak seedlings in mixed forests in the southern appalachian mountains. | diversity of ectotrophic mycobionts on outplanted seedlings of two oak species (quercus rubra and quercus prinus) was estimated at two sites in mature mixed forests in the southern appalachian mountains by sequencing nuclear 5.8s rrna genes and the flanking internal transcribed spacer regions i and ii (its). the seedlings captured a high diversity of mycorrhizal its-types and late-stage fungi were well represented. total richness was 75 types, with 42 types having a frequency of only one. the fi ... | 2005 | 15723674 |
| should models of disease dynamics in herbivorous insects include the effects of variability in host-plant foliage quality? | interactions between insects and their baculovirus pathogens are often described using simple disease models. baculoviruses, however, are transmitted when insects consume virus-contaminated foliage, and foliage variability, whether within or between host-plant species, can affect viral infectiousness. insect-baculovirus interactions may thus be embedded in a tritrophic interaction with the insect's host plant, but disease models include only the host and the pathogen. we tested these models by m ... | 2004 | 15729637 |
| 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 |
| how are leaves plumbed inside a branch? differences in leaf-to-leaf hydraulic sectoriality among six temperate tree species. | the transport of water, sugar, and nutrients in trees is restricted to specific vascular pathways, and thus organs may be relatively isolated from one another (i.e. sectored). strongly sectored leaf-to-leaf pathways have been shown for the transport of sugar and signal molecules within a shoot, but not previously for water transport. the hydraulic sectoriality of leaf-to-leaf pathways was determined for current year shoots of six temperate deciduous tree species (three ring-porous: castanea dent ... | 2005 | 15983007 |
| effects of aqueous extracts from leaves and leaf litter on the abundance and diversity of soil gymnamoebae in laboratory microcosm cultures. | the distribution and abundance of microbiota in soil and litter may be significantly affected by the quality and quantity of localized patches of leaf organic matter. this study examined the relative effects of aqueous extracts of shed autumn leaves from american beech (fagus grandifolia), sugar maple (acer saccharum), red oak (quercus rubra), and white oak (quercus alba) on the density and diversity of gymnamoebae in laboratory cultures. overall, the beech leaf extract produced the most growth ... | 2005 | 16014018 |
| strength analysis of titanium and resorbable internal fixation in a mandibulotomy model. | mandibulotomy is used to access various tumors of the tongue base, posterior oral cavity, pharynx, parapharyngeal space, and cranial base. internal fixation using titanium plates and screws is the most common method of stabilization. these have the potential for interference with radiotherapy delivery. this in vitro study compares the strength of titanium and resorbable internal fixation in a mandibulotomy model by analyzing the force required for plate and screw breakage. | 2005 | 16094588 |
| phenolic compounds in red oak and sugar maple leaves have prooxidant activities in the midgut fluids of malacosoma disstria and orgyia leucostigma caterpillars. | phenolic compounds are generally believed to be key components of the oxidative defenses of plants against pathogens and herbivores. however, phenolic oxidation in the gut fluids of insect herbivores has rarely been demonstrated, and some phenolics could act as antioxidants rather than prooxidants. we compared the overall activities of the phenolic compounds in red oak (quercus rubra) and sugar maple (acer saccharum) leaves in the midgut fluids of two caterpillar species, malacosoma disstria (ph ... | 2005 | 16124227 |
| forest regeneration composition and development in upland, mixed-oak forests. | advance regeneration in 52 mature mixed-oak stands was analyzed and described. red maple (acer rubrum l.) was the most abundant species in the study area. among oak (quercus) species, northern red oak (q. rubra l.) was the most abundant within the allegheny plateau physiographic province, whereas chestnut oak (q. montana l.) was the most abundant within the ridge and valley physiographic province. sixteen stands, for which data are available through the fourth growing season following harvest, w ... | 2005 | 16137935 |
| enzymology of gallotannin and ellagitannin biosynthesis. | gallotannins and ellagitannins, the two subclasses of hydrolyzable tannins, are derivatives of 1,2,3,4,6-penta-o-galloyl-beta-d-glucopyranose. enzyme studies with extracts from oak leaves (quercus robur, syn. quercus pedunculata; quercus rubra) and from staghorn sumac (rhus typhina) revealed that this pivotal intermediate is synthesized from beta-glucogallin (1-o-galloyl-beta-d-glucopyranose) by a series of strictly position-specific galloylation steps, affording so-called 'simple' gallotannins, ... | 2005 | 16153405 |
| sapling growth as a function of light and landscape-level variation in soil water and foliar nitrogen in northern michigan. | interspecific differences in sapling growth responses to soil resources could influence species distributions across soil resource gradients. i calibrated models of radial growth as a function of light intensity and landscape-level variation in soil water and foliar n for saplings of four canopy tree species, which differ in adult distributions across soil resource gradients. model formulations, characterizing different resource effects and modes of influencing growth, were compared based on rel ... | 2006 | 16208492 |
| genetic structure inside a declining red oak community in old-growth forest. | problems with oak regeneration have been documented in the last 50 years at numerous sites in the midwestern united states. we applied nuclear microsatellites to examine the demographic and fine-scale spatial genetic structure of red oaks in two old-growth stands in indiana. oaks in one stand have declined in numbers over the past several decades whereas oaks in the other, smaller stand have increased. large amounts of genetic variation were maintained within stands, and there was slight but sig ... | 2005 | 16251518 |
| response of the nitrogen isotopic composition of tree-rings following tree-clearing and land-use change. | clear-cutting of forests affects the nitrogen cycle and the nitrogen isotopic composition of bioavailable ammonium and nitrate in the soil. here, we have used nitrogen isotopic variations of tree-rings in red oak (quercus rubra) and white oak (quercus alba) as indicators of changes in the nitrogen cycle on a local scale. the delta15n values of late-wood from trees at two remnant forest stands in ontario, canada, that underwent large-scale tree-clearing and permanent land-use change at different ... | 2005 | 16295836 |
| anaerobic fermentation of woody biomass pretreated with supercritical ammonia. | the degradability of ground hardwood by thermophilic anaerobic bacteria (clostridium thermocellum with or without thermoanaerobacter strain b6a) was greatly enhanced by pretreatment of the substrate with supercritical ammonia. relative to c. thermocellum monocultures, cocultures of c. thermocellum and thermoanaerobacter strain b6a degraded 1.5-fold more pretreated soft maple but produced 2- to 5-fold more fermentation endproducts because thermoanaerobacter sp. removed reducing sugars produced by ... | 1986 | 16347166 |
| interspecific variation in nighttime transpiration and stomatal conductance in a mixed new england deciduous forest. | transpiration is generally assumed to be insignificant at night when stomata close in response to the lack of photosynthetically active radiation. however, there is increasing evidence that the stomata of some species remain open at night, which would allow for nighttime transpiration if there were a sufficient environmental driving force. we examined nighttime water use in co-occurring species in a mixed deciduous stand at harvard forest, ma, using whole-tree and leaf-level measurements. diurna ... | 2006 | 16414920 |
| feeding responses to selected alkaloids by gypsy moth larvae, lymantria dispar (l.). | deterrent compounds are important in influencing the food selection of many phytophagous insects. plants containing deterrents, such as alkaloids, are generally unfavored and typically avoided by many polyphagous lepidopteran species, including the gypsy moth lymantria dispar (l.) (lepidoptera: lymantriidae). we tested the deterrent effects of eight alkaloids using two-choice feeding bioassays. each alkaloid was applied at biologically relevant concentrations to glass fiber disks and leaf disks ... | 2006 | 16474969 |
| inferring colonization history from analyses of spatial genetic structure within populations of pinus strobus and quercus rubra. | many factors interact to determine genetic structure within populations including adult density, the mating system, colonization history, natural selection, and the mechanism and spatial patterns of gene dispersal. we examined spatial genetic structure within colonizing populations of quercus rubra seedlings and pinus strobus juveniles and adults in an aspen-white pine forest in northern michigan, usa. a 20-year spatially explicit demographic study of the forest enables us to interpret the resul ... | 2006 | 16499707 |
| intracellular distribution of p-nitrophenyl-phosphatase in plants. | less than 10% of the acid p-nitrophenylphosphatase activity of plant extracts was sedimentable under a variety of conditions including zonal centrifugation. the sedimentable fraction did not show the latency properties characteristic of animal lysosomes. we conclude that, at least operationally, plant acid phosphatase is a soluble enzyme and that it is not suitable as a lysosomal marker. the plant tissues employed were pea cotyledons, cauliflower florets, turnip storage organs, onion embryos, an ... | 1967 | 16656577 |
| production of isoprene by leaf tissue. | isoprene production by hamamelis virginiana l. and quercus borealis michx. leaves was studied. when ambient co(2) concentrations were maintained with bicarbonate buffers, the rate of isoprene production at 125 microliters per liter of co(2) was approximately four times that at 250 microliters per liter of co(2). isoprene production was drastically inhibited by 97% o(2). dichlorodimethylphenylurea (0.1 mm), nahso(3) (10 mm), and alpha-hydroxy-2-pyridinemethanesulfonic acid (10 mm) inhibited isopr ... | 1975 | 16659231 |
| units of freezing of deep supercooled water in woody xylem. | the low temperature exotherms (lte) of 1-year-old twigs of haralson apple (malus pumila mill.), shagbark hickory (carya ovata [mill.] k. koch), green ash (fraxinus pennsylvanica marsh), honey locust (gleditsia triacanthos l.), american chestnut (castanea dentata [marsh] borkh.), and red oak (quercus rubra l.) were determined by differential thermal analysis (dta). in one type of experiment freezing during a dta experiment was halted for up to 2.5 hours after part of the supercooled water had fro ... | 1980 | 16661390 |
| al and ca alteration of membrane permeability of quercus rubra root cortex cells. | this study was undertaken to quantify the effect of aluminum and calcium on membrane permeability. the influence of ca(2+) (0.2-3.7 millimolar) and al(3+) (0-3.7 millimolar) on the permeability of root cortical cells of quercus rubra was measured using three nonelectrolytes (urea, methyl urea, and ethyl urea) as permeators of progressively increasing lipid solubility. water permeability was also measured. al(3+) (a) increased membrane permeability to the nonelectrolytes, (b) decreased the membra ... | 1987 | 16665194 |