bluuebunny/crossref_metadata_2025 huggingface dataset:
Seasonal patterns of root nodule growth, endophyte morphology, nitrogenase activity, and shoot development in Myrica gale
Authors: Schwintzer Christa R. , Berry Alison M. , Disney Lynn D.
Published: October 2007

Myrica gale L. populations growing in central Massachusetts were observed throughout the ice-free season. Nitrogenase activity appeared in mid-May shortly after budbreak, was at its maximum between late June and mid-August, and disappeared in late October after all leaves had fallen. Growth of overwintering nodules began in early May and was largely complete by mid-July. Most nodules (88%) lived for 3 years or less and 61% of the nodule biomass present in autumn was produced during the current season.Colonizing hyphae of the Frankia sp. endophyte were seen throughout the year in partially expanded cortical cells near the nodule lobe apex. Vesicles first appeared in mature cortical cells coincident with the onset of nitrogenase activity in mid-May, occupied the bulk of the infected tissue during the summer, and disappeared as nitrogenase activity ceased in late October. Evidence is presented that the vesicles are the site of nitrogenase activity and are newly produced each season in freshly formed nodule lobe tissue. Sporangia frequently formed in mature infected cells in nodules at one site but were rare at another. The processes described here in M. gale are probably typical of winter-deciduous actinorhizal plants.
Modifications expérimentales de la morphogénèse et des géotropismes dans le système racinaire de jeunes chênes
Authors: Riedacker Arthur , Dexheimer Jean , Tavakol Rahmat , Alaoui Hachimi
Published: October 2007

Seedlings of English oak (Quercus robur L.) and cork oak (Quercus suber L.) grown in minirhizotrons have (i) semiplagiogeotropic lateral roots which reorient their tip when placed in certain positions; their growth is very brief; (ii) taproots which are strongly orthogeotropic when they are short and weakly orthogeotropic when they are 2 m long; (iii) replacement taproots, appearing after a decapitation of the taproot, which are either orthogeotropic or slightly oblique. The orthogeotropic caracteristics of taproots and replacement taproots seem difficult to alter.Deviating, slowing the growth, blocking, or drying the tip of the taproot induces various transformations of lateral roots. Axial growth, radial growth, growth of the ramifications, and geotropism of the lateral roots can be changed separately, but in a certain order. Growth correlations within the root system of young oaks are compared with those already studied in the root system of Theobroma cacao L. The nature of the correlations is discussed.
Ecology of an alpine–subalpine meadow complex in the Olympic Mountains, Washington
Authors: Belsky Joy , Moral Roger Del
Published: October 2007

Eleven sites representing the range of alpine and subalpine community types in Deer Park were chosen for an intensive study of high-elevational meadow habitats in the Olympic Mountains, Washington. The vegetation, soils, and important physical features of each site are described.The 11 sites were ordered by reciprocal averaging. The resulting first axis was interpreted as being a moisture–exposure gradient which separates the mesic subalpine meadows from the xeric alpine meadows. This gradient is determined by snowmelt patterns, aspect, and wind. Mesic subalpine sites are sheltered from the wind and direct insolation. Xeric alpine sites have shallow or no snowpacks and receive the full impact of the wind and sun. The second axis is a soil stability gradient that predominately affects the xeric sites. Stable soils are protected from wind erosion, frost heaving, and needle ice by windbreaks and long-lasting snowpacks.
Alternate methods of analysing water potential isotherms: some cautions and clarifications. II. Curvilinearity in water potential isotherms
Authors: Tyree Melvin T. , Richter Hanno
Published: October 2007

The Hammel pressure bomb technique has been used to obtain measurements of water potential, Ψ, and relative water content, R*, on single leaves of Populus spp., Helianthus annuus, and Fraxinus ornus. The data were plotted either as Ψ versus 1/R* or as 1/Ψ versus R* and analysed by linear regression in the region where cell turgor was thought to be zero. In some cases the Ψ versus 1/R* transformation showed curvature in the zero turgor region whereas less curvature was found in the same region of R* in the 1/Ψ versus R* transformation. In theory, curvature can appear in the Ψ versus 1/R* transformation whenever a significant fraction of tissue water is contained in the apoplast, and this theoretical prediction can be demonstrated by some of the data in this paper. The presence or absence of curvature in the two transformations can also be due to (1) apoplast compressibility, (2) the development of negative turgor pressure in living cells, and (3) the nonideality of the osmotic solutions in living cells. Linear regressions performed on curved data plots will lead to errors in the estimation of π0, the osmotic pressure at full hydration, and of other parameters derived from the analysis.
A biosystematic study of the Solidago canadensis (Compositae) complex. I. The Ontario populations
Authors: Melville Mentor R. , Morton John K.
Published: October 2007

Populations from 138 locations in Ontario were sampled and found to contain three levels of polyploidy: diploid, tetraploid, andhexaploid. Five taxa are recognized: Solidago canadensis Linn. var. canadensis (2n = 18) and var. hargeri Fem. (2n = 18), S. gigantea Ait. (2n = 18 and 36), S. altissima Linn. (2n = 54), and S. lepida DC. (2n = 54). All are obligate outbreeders and are pollinated by a wide range of insects. The four species are separated by major genetic barriers and attempts to cross them have not been successful except in the case of S. altissima and S. lepida where a single hybrid plant has been raised. The two varieties of S. canadensis are interfertile and intergrade in nature. The two cytotypes of S. gigantea appear to be morphologically inseparable but are genetically isolated. Solidago canadensis var. canadensis and S. altissima are abundant, widespread, and aggressive weeds. Solidago canadensis var. hargeri grows in deciduous woodland in the south of the province. Solidago gigantea grows in wet situations, the tetraploid being of widespread occurrence and the diploid confined to the southeast of the province. Solidago lepida only occurs in northern Ontario.
Zoospore ultrastructure of Polymyxa graminis (Plasmodiophoromycetes)
Authors: Barr Donald J. S. , Allan Paula M. E.
Published: October 2007

The ultrastructure of the Polymyxa graminis Ledingham zoospore is described with emphasis on the flagellar apparatus. The unique characteristics of this zoospore are the two kinds of rootlets which extend from the proximal ends of each kinetosome to the plasmalemma. One rootlet consists of a microtubule pair with electron-opaque backing along part of its length which ends abruptly at the plasmalemma. The other rootlet consists of three microtubules which, on reaching the plasmalemma, curve around sharply and extend ribbonlike along the side of the zoospore adjacent to the plasmalemma. This arrangement of rootlets is replicated on the second kinetosome. The kinetosome and transition zone are structurally similar to those in certain protozoa and unlike those found in other groupings of zoosporic fungi or algae.
An evalution of the nitrous acid – 3-methyl-2-benzothiazolinone hydrazone hydrochloride – ferric chloride assay for chitin in rust fungi and rust-infected tissue
Authors: Kaminskyj Susan G. W. , Heath Michèle C.
Published: October 2007

The growth of the bean rust and cowpea rust fungi was examined in cultivars of French bean and cowpea using light microscopy and the nitrous acid – 3-methyl-2-benzothiazolinone hydrazone hydrochloride – ferric chloride assay for chitin. Comparison of the results indicated that the chitin assay did not detect changes in vegetative growth but only detected substances present in mature and developing urediospores. Examination of urediospores indicated that the reactive component(s) was hexosamine, probably glucosamine, but not chitin. The presence of strongly reactive substances in the urediospores, and the apparent low level of chitin in vegetative mycelium compared with that in the mycelium of the commercial mushroom, suggest that this chitin assay is of little value in estimating rust fungus growth in infected plant tissue.
Peatland vegetation organization and dynamics in the western subarctic, Northwest Territories, Canada
Authors: Jasieniuk M. A. , Johnson E. A.
Published: October 2007

Species frequency abundance was determined in 77 peatland stands and the variance partitioned between the effects of fire and habitat. Each variance partition was then analyzed using principal component analysis. The resulting habitat ordination was interpreted in terms of a moisture–nutrient gradient and a sphagnum substrate gradient. The fire frequency ordination gave a gradient of plant adaptations to the interval between fires. Vegetation change after fire is predominantly change in species abundance. It consists of a regeneration to the predisturbance species composition which depends on the moisture–nutrient and sphagnum substrate conditions. Changes in species composition are suggested to be due to major changes in habitat characteristics usually the result of water level fluctuations. A discussion of the frequency of disturbance due to water level fluctuations and fire for different peatland communities is presented.
Effects of pea (Pisum sativum) genotypes and Rhizobium leguminosarum strains on N2(C2H2) fixation and growth
Authors: Hobbs S. L. A. , Mahon J. D.
Published: October 2007

Factors affecting the efficiency of selection for increased N2(C2H2) fixation in Pisum sativum L. were examined. Ten genotypes, previously selected for variability in fixation rates when inoculated with commercial (mixed strain) Rhizobium leguminosarum, were examined using pure strain (128C52 and 10004) inocula. Strains and genotypes both affected fixation rates, but genotype × strain interaction was also found. Increases in relative growth rate (RGR) were associated with increases in fixation across strains but not with increases in fixation across genotypes. These differences in the response to changes of strain and genotype were further studied over a 4-week period using genotypes specifically selected for high or low rates of C2H2 reduction with both strains. Strain 128C52 and the genotypes selected for high rates of C2H2 reduction produced greater maximum rates of C2H2 reduction than their low counterparts, but the strains also differed in the time at which fixation began. Plants inoculated with strain 128C52 showed significant rates 3–4 days before those inoculated with strain 10004. This earlier availability of nitrogen in the former may have alleviated the early nitrogen starvation and hence increased RGR. All differences in fixation rate were related to nodulation. Although early nodulation and fixation are apparently important to plant growth under N-free conditions, the expression of genotype or strain variability might be reduced by combined N in the field owing to its inhibitory effect on fixation.
Nitrate modification of photosynthesis and photoassimilate export in young nodulated soybean plants
Authors: Ursino D. J. , Hunter D. M. , Laing R. D. , Keighley J. L. S.
Published: October 2007

Soybean plants (cv. Harosoy 63) inoculated with rhizobia were germinated from seed and beginning on day 7 after planting were subjected to one of four patterns of nutrient fertilization. One group received a nutrient solution containing 5 mM nitrate, a second group received nitrate-free nutrient solution, and two other groups received nitrate-containing solution either from days 7 to 13 or from days 14 to 20. On day 21 rates of leaf photosynthetic CO2 uptake and nitrate reductase activity were measured, as well as the capacities of the leaf to export recent photosynthate and of the nodules to reduce acetylene. The data support the hypothesis that sufficient nitrate availability in the leaves of young soybean plants can modify both photosynthetic CO2 uptake and light-mediated photoassimilate export to an extent that nodule development and the capacity for nitrogen fixation are reduced.
The relationship between ozone insensitivity, lipid-soluble antioxidants, and superoxide dismutase in Phaseolus vulgaris
Authors: McKersie B. D. , Beversdorf W. D. , Hucl P.
Published: October 2007

Ozone insensitivity was assessed by three methods (visual rating, leakage of amino acids, and leakage of total electrolytes from leaf discs), and related to the levels of lipid-soluble antioxidants and superoxide dismutase activity in the primary leaves of different ages and of different cultivars of Phaseolus vulgaris L. The most sensitive indicator of ozone injury was visual rating. The increased variability associated with measurements of amino acid or total electrolyte leakage masked differences among cultivars which could be detected by visual rating. The correlations among the three measures of injury were high. Ozone tolerance of the primary leaf decreased between 8 and 18 days after planting and varied significantly among the 10 cultivars tested. Similarly, significant differences in lipid-soluble antioxidant content and superoxide dismutase activity were measured, but a correlation with ozone insensitivity was not established. Exposure to 20 pphm ozone for 24 h induced higher quantities of lipid-soluble antioxidant in the susceptible cv. Seafarer but not in the tolerant cv. Goldcrop. Superoxide dismutase increased similarly in both cultivars. The physiological mechanism of ozone insensitivity in the primary leaves of these cultivars of P. vulgaris was not shown to involve increased levels of lipid-soluble antioxidants or superoxide dismutase.
Chemosystematic studies in the genus Pinus. IV. Leaf oil composition and geographic variation in jack pine of eastern North America
Authors: Lapp Martin S. , Rudloff E. von
Published: October 2007

Leaf terpenes of 420 jack pines from 43 sites (Petawawa provenances) in eastern North America were analyzed by gas–liquid chromatography (GLC). In most trees the major components were α-pinene, β-pinene, myrcene, car-3-ene, limonene, β-phellandrene, and bornyl acetate. Eighteen other monoterpenes were identified and 13 sesquiterpenes were characterized by their spectral properties and GLC retention times. These data were analyzed by centroid cluster analysis of the mean-squared Euclidean distances, which showed that jack pine is a diverse species of two major terpene types with eight minor types and a few outlying individual trees. With the exception that the minor clusters and outliers tend to occur at the fringes of the jack pine range, there is no obvious geographic pattern to these clusters.
The anatomy of the leaf of red pine, Pinus resinosa. I. Nonvascular tissues
Authors: Gambles R. L. , Dengler R. E.
Published: October 2007

The general morphology of the secondary needle-leaf of Pinus resinosa and the structure of the dermal and ground tissues are described. An anatomical and ultrastructural study of the mature midregion has shown that the leaf is surrounded by a uniseriate epidermis of dead, thick-walled cells which is subtended by a single layer of living hypodermal cells that contain few recognizable organelles. Plicate mesophyll cells occupy the largest portion of the leaf cross-sectional area. These cells have a thin parietal cytoplasm rich in organelles, surrounding a tannin-filled vacuole. Two resin canals are found in the mesophyll towards the adaxial leaf surface and there may be up to three towards the abaxial surface. The resin canal epithelial cells are living at maturity but their cytoplasm appears metabolically inactive.
Formation of epicuticular wax and its effect on water loss in cabbage plants regenerated from shoot-tip culture
Authors: Sutter E. , Langhans R. W.
Published: October 2007

Observation by scanning electron microscopy (SEM) revealed that cabbage plants in vitro had no structured epicuticular wax whereas plants grown in a growth chamber or in the greenhouse had considerable amounts of structured epicuticular wax. Plants grown in vitro developed increasing amounts of structured epicuticular wax after transfer to the greenhouse. Water loss per unit leaf area was greater in plants recently removed from in vitro conditions than in either plants grown in the growth chamber or in cultured plants that had been hardened off. Epicuticular wax was formed in plants grown in vitro at 35% relative humidity indicating that relative humidity is an important factor in the in vitro development of wax. The contribution of light to the formation of epicuticular wax and the relationship of the wax to survival of the plants when they are removed from in vitro culture are discussed.
Breeding systems of northeastern North American Spiranthes (Orchidaceae)
Authors: Catling Paul M.
Published: October 2007

Breeding systems in northeastern North American Spiranthes orchids were studied to provide background information for taxonomic and evolutionary interpretations. Pollination experiments revealed that Spiranthes casei var. casei, S. cernua var. cernua, S. magnicamporum (southwestern Ontario), and S. ochroleuca (southern Nova Scotia) are agamospermic, while S. lacera var. lacera, S. lacera var. gracilis, S. laciniata, S. magnicamporum (Illinois), S. ochroleuca (Pennsylvania, New York), S. romanzoffiana, S. tuberosa, and S. vernalis are sexual. In the sexual taxa, cross-pollination is followed by earlier dehiscence of capsules, a higher percentage of ovaries with seeds, and a higher percentage of seed coats with well-developed embryos than either self-pollination or geitonogamous pollination. This may be explained by partial self-incompatibility involving restricted pollen-tube growth and (or) inbreeding depression. In Spiranthes romanzoffiana and races of S. ochroleuca requiring pollination for seed development, the two or three layers of cells comprising the inner integument degenerate after fertilization. Seed produced by species requiring pollination (i.e., produced sexually) is monoembryonic with the embryo located centrally. Examination of stained serial sections in successive developmental stages indicated that agamospermy in northeastern taxa of Spiranthes is by adventitious embryony, the embryos (one or more) being formed by proliferation of the micropylar inner integument beginning at the time of the first division of the megasporocyte. Direct anatomical evidence of adventitious embryony was obtained for S. casei var. casei, S. casei var. novaescotiae, S. cernua var. cernua, and S. magnicamporum (Ontario). Adventitious embryony in northeastern Spiranthes taxa is autonomous but not necessarily obligate and can be readily detected because of its association with polyembryonic seed, extruded embryos, free embryos, and ruptured embryo sacs. Three northeastern taxa are characterized by autonomous agamospermy throughout their areas of distribution, while another three are agamospermic only at their northeastern range limits. These six comprise a taxonomically complex group. In contrast, correlative seed morphology indicates that eight taxonomically distinctive northeastern taxa are uniformly sexual, some clearly favouring outbreeding. Adventitious embryony in northeastern North American Spiranthes is associated with glaciated territory, northeastern range limits, and more or less isolated bioclimatic zones.
The morphology of false anthers in Craterostigma plantagineum and Torenia polygonoides (Scrophulariaceae)
Authors: Magin Norbert , Classen Regine , Gack Claudia
Published: October 2007

The ontogenesis of the prominent excrescences of the filament of two melittophilous species is investigated and the biological implications are discussed. In Craterostigma plantagineum Hochst. the bases of the filament bulges are fused with the lower lip of the corolla. The bulges are bright yellow, of grainy structure, and they flank the entrance of the flower tube. This character syndrome can be interpreted as a plastic (three-dimensional) false anther or anther dummy. The flower of Torenia polygonoides Benth. carries a yellow, spotlike anther dummy in the centre of the lower lip. The staminal excrescences of T. polygonoides are completely free of the lower lip of the corolla, pin-shaped, and of a light pink colour. Thus, they lack the characteristic, yellow signal colour that is typical for anther dummies in general. Possibly, they have no optical function at all, but act as a guide rail.
Efficacy of certain plant extracts against seed-borne infection of Trichoconiella padwickii in paddy (Oryza sativa)
Authors: Shetty Sudheer A. , Prakash H. S. , Shetty H. Shekara
Published: October 2007

Aqueous extracts of leaves, bark, stems, and seeds of Strychnos nux-vomica L., bulbs of Allium sativum L., rhizome of Zingiber officinale Rasc., leaves of Ocimum basilicum L., and fruits of Azadirachta indica A. Juss were used to control Trichoconiella padwickii (Ganguly) Jain in seeds of paddy (Oryza sativa L.). The seeds were soaked in 10, 20, and 30% extracts (w/v) for 12, 24, and 48 h. All the extracts had significant inhibitory effects on the fungus. Stem, bark, and seed extracts (20% w/v) of S. nux-vomica were more effective than other plant extracts and 0.3% of Mancozeb in controlling the fungus. None of the plant extracts were phytotoxic at the tested concentrations.
Regulation of proline content of Chlorella autotrophica in response to changes in salinity
Authors: Laliberté Gilles , Hellebust Johan A.
Published: October 2007

In Chlorella autotrophica, proline, chlorophyll, and protein synthesis took place almost exclusively in the light. No evidence for proline degradation in the dark was obtained. An osmotic upshock from 50 to 150% artificial seawater caused a temporary inhibition of photosynthesis in this alga. An osmotic downshock from 150 to 50% artificial seawater had no effect on its photosynthetic rate. Synthesis of proline, the main osmoregulatory solute in C. autotrophica, showed no lag phase following an upshock and was not inhibited in the presence of cycloheximide. These results suggest that the enzymes of the proline pathway are not synthesized de novo in response to the upshock. In the dark, the rate of proline synthesis was lower, whereas the presence of acetate allowed a rate of proline synthesis similar to that of cells in the light. Synthesis of proline in the dark in the presence of acetate was dependent on the induction of isocitrate lyase. Thus the glyoxylate cycle plays a key role in furnishing carbon and reducing power for proline synthesis in the dark. Following a sudden downshock, more than 55% of the proline content leaked out of the cell in the first 5 min due to transient breakdown in membrane permeability. However, if the downshock is gradual, proline is oxidized by the cells rather than being leaking out.
Ultrastructure and cytochemistry of extramural substances associated with intercellular hyphae of several rust fungi
Authors: Harder D. E. , Chong J. , Rohringer R. , Mendgen K. , Schneider A. , Welter K. , Knauf G.
Published: October 2007

Several types of extramural substance(s) associated with rust fungal intercellular hyphae were identified using a variety of tissue processing techniques. With conventional glutaraldehyde–OsO4 fixing and uranyl acetate – lead citrate staining, little material could be discerned on the hyphal surfaces in nonsporulating areas except at locations of cell–cell contact, where a lightly staining fibrous or darker staining amorphous material was apparent. Freeze-substitution or freeze-fracturing preserved greater amounts of coating material, which could be distinguished from the outer fungal wall layers. In freeze-substituted samples the extramural material was amorphous in nonsporulating areas, whereas near sporulating zones it had a fibrous consistency, with the fibrils oriented perpendicularly to the fungal wall. At locations of cell–cell contact there was additional extramural material that was composed of randomly oriented fibrils or was amorphous and densely staining. All types of extramural material stained positively with the periodate – thiocarbahydrazide – silver proteinate or periodate – chromate–phosphotungstate stains, but Concanavalin A bound only to some of the dense amorphous material. Sodium ethoxide etching and platinum–carbon shadowing also revealed the extramural material. When rust-infected wheat leaves were flooded with suspensions of colloidal gold, adhesion of gold particles occurred outside the hyphal walls and coincided with the location of extramural material.
Seed dispersal in the cycad Zamia pumila in Florida
Authors: Tang William
Published: October 2007

Seed dispersal of the herbaceous cycad Zamia pumila was studied in the rockland pine forests of southeast Florida. Dispersal activity was found to occur over 6 months and was concentrated in two periods: after seed ripening and prior to seed germination. Seed mass and pulp-to-seed ratios were positively correlated with dispersal success at one study site. Seed shadows were generally asymmetrical in direction, with seeds tending to be deposited under nearby shrubs. Seed germination and seedling establishment is higher in shade than in sun, suggesting that the lower light intensities under shrubs are safe sites for seeds and seedlings.
Plugging of the xylem vessel of barley induced by a high molecular weight phytotoxic glycoprotein from Rhynchosporium secalis
Authors: Mazars C. , Poletti P. , Petitprez M. , Albertini L. , Auriol P.
Published: October 2007

Small concentrations of a high molecular weight phytotoxic glycoprotein obtained from culture filtrates of Rhynchosporium secalis (Oud.) Davis induced chlorosis and necrosis in barley; these symptoms were similar to those observed during the final stages of disease caused by this pathogen in naturally infected barley leaves. Histochemical studies indicated that cells of leaf tissues treated with the glycoprotein became disorganized. We observed changes such as the collapse of epidermal anticlinal walls, tissue necrosis, and plugging of xylem vessels. Histochemical and immunofluorescent techniques that localized the glycoprotein toxin indicated that, at least in part, the plugging results from a plant response stimulated by the toxic glycoprotein.
Grasses of the Queen Elizabeth Islands
Authors: McLachlan K. I. , Aiken S. G. , Lefkovitch L. P. , Edlund S. A.
Published: October 2007

For the 27 species and three hybrid taxa of grasses known to occur in the Queen Elizabeth Islands of the Canadian High Arctic, a key to the taxa, and tables comparing vegetative, inflorescence, and spikelet characters are presented. Nomenclature, including some synonymy, notes on variable characters or characteristics not presented in the tables, ecological and geographical occurrences, as well as comments on taxonomy are given.
Sporogenesis and septum schizolysis in Dipodascus aggregates
Authors: Tsuneda A. , Murakami S.
Published: October 2007

Asci, ascospores, and arthroconidia of Dipodascus aggregatus were examined by electron microscopy. Freeze-drying of mature asci caused rupture of the ascal walls and made it possible to observe capsulated ascospores in situ. Two types of septa occurred: (i) one having a remarkably thickened cross wall which protruded to form a circumferential ridge on the hyphae, and (ii) the other without such a bulging ridge. Schizolysis of these septa resulted in the formation of morphologically distinct arthroconidia. The scizolytic process of the ridged septa was demonstrated in detail. There was no evidence to support that the plasmadesmal canals in the septa function as disjunctive pegs in the process of arthroconidial separation.
Correlation between early root production, carbohydrate metabolism, and subsequent biomass production in hybrid poplar
Authors: Tschaplinski T. J. , Blake T. J.
Published: October 2007

The relationship between the rooting patterns of five poplar hybrids and stem carbohydrate dynamics was investigated to determine if the availability or metabolism of carbohydrates was limiting early root production of cuttings. Differences in early root production (i.e., number, length, and dry weight) after 17 days paralleled the subsequent differences in accumulation of aboveground biomass that were observed when two Populus balsamifera L. × deltoides Bartr. (Jackii 4 and Jackii 7) and three Populus deltoides Bartr. × nigra L. (DN 2, DN 22, and DN 15) hybrids were compared. Total root length and dry weight of Jackii 4 was four times that of Jackii 7. Both DN 2 and DN 22 had a total root length twice that of DN 15. Rooting characteristics may be useful criteria for selection of productive clones. Carbohydrate analysis of stem cuttings suggested that hybrids differing in biomass production displayed different patterns of carbohydrate utilization. The concentrations of glucose and myoinositol declined more in faster growing hybrids (Jackii 4, DN 2, DN 22) than in slower growing hybrids (Jackii 7, DN 15). The results suggest that faster growing hybrids consume monosaccharides in growth processes, whereas the slower growing hybrids convert monosaccharides into alternative storage forms and use less in growth processes. The initial myoinositol concentration in stem cuttings of poplar hybrids was correlated (r2 = 0.95) with root dry weight produced after 17 days, but the initial starch concentration was unrelated to later root biomass production. The results suggest that initial myoinositol concentration in cuttings may be used in early selection for rooting performance.
Ultrastructural studies on infection of sclerotia of Sclerotinia sclerotiorum by Talaromyces flavus
Authors: McLaren D. L. , Huang H. C. , Rimmer S. R. , Kokko E. G.
Published: October 2007

Talaromyces flavus is a destructive hyperparasite capable of infecting sclerotia of Sclerotinia sclerotiorum. Examinations of sclerotia by transmission electron microscopy at 3, 7, and 12 days after inoculation revealed that hyphae of T. flavus penetrated the rind cell walls directly. Etching of the cell walls at the penetration site was evident. This suggests that wall-lysing enzymes may be involved in the process of infection. Hyphae of T. flavus grew both intercellularly and intracellularly throughout the rind, cortical, and medullary tissues. Ramification of the hyperparasite in the sclerotium resulted in destruction and collapse of sclerotial tissues.
Enhancement of cell division in wheat root tips and growth of root elongation zone induced by Azospirillum brasilense Cd
Authors: Levanony Hanna , Bashan Y.
Published: October 2007

Inoculation by bacterial infiltration of germinating wheat seeds with 106–108 colony-forming units of the beneficial rhizosphere bacteria, Azospirillum brasilense Cd, significantly increased cell division in root tips during germination. The phenomenon occurred mainly in the second wave, i.e., 24 h after inoculation, of cell division in the meristem. Seed inoculation significantly enlarged the elongation zone of their roots. These inoculation effects suggest that the larger root system, which is usually observed in inoculated plants, may originate in part from the enhancement of cell division and the intensive growth of the elongation zone of seminal roots. Key words: Azospirillium, beneficial bacteria, bacteria–root interaction, cell division, rhizosphere bacteria, root growth.
Mycorrhizal response in wheat cultivars: relationship to phosphorus
Authors: Hetrick B. A. D. , Wilson G. W. T. , Todd T. C.
Published: October 2007

The effect of five mycorrhizal fungi on the growth of 10 wheat cultivars under three phosphorus regimes was assessed in a greenhouse study. Six of the cultivars responded positively, while four responded negatively or were nonresponsive to mycorrhizal inoculation. The responses of the individual cultivars were consistent regardless of inoculum source, suggesting that mycorrhizal responsiveness is an inherited trait rather than a response to individual fungi. Mycorrhizal responsiveness decreased with P fertilization for cultivars that were dependent on the symbiosis, but it was unaffected by P fertilization in cultivars that were negatively impacted by the mycorrhizae. Mycorrhizal and P responsiveness of each cultivar were highly correlated (r = 0.94), suggesting that P responsiveness may be a good predictor of the mycorrhizal dependence of selected wheat cultivars. The relationship between wheat biomass production and percentage root colonization was positive for cultivars, which responded favorably to the symbiosis, and negative for cultivars, which responded negatively or were nonresponsive to mycorrhizal inoculation. Amendment with P did not significantly affect these relationships. To determine whether differences in mycorrhizal responsiveness are related to nutrient uptake by the fungus,32P uptake of Turkey (responsive cultivar) and Newton (nonresponsive cultivar) was controlled by severing the mycorrhizal hyphae in a split-pot experiment. Plants with intact hyphae absorbed more32P than those with severed hyphae for both cultivars, and significantly more counts per minute of32P were evident in Newton than in Turkey, suggesting that mycorrhizal function is not impaired even in cultivars that do not display a biomass increase in response to mycorrhizal symbiosis. Keywords: vesicular–arbuscular mycorrhizae, pathogenesis, growth response, mycorrhizal symbiosis.
Changes in distribution of short pectic polysaccharides induced by monovalent ions in the Nitella cell wall
Authors: Gillet C. , Liners F.
Published: October 2007

Nitella cell walls exhibit a major loss of pectin when the adsorbed bivalent ions are exchanged for monovalents. 2F4 monoclonal antibody, which recognizes a conformational epitope of homogalacturonic acid induced by calcium ions, was complexed to colloidal gold and used to localize, by means of the electron microscope, the wall regions from which the leakage occurred. Comparison of the labelling between nonpretreated cell walls and NaCl or LiCl pretreated ones, with or without incubation in CDTA or in NaOH, reveals that monovalent ions induce the solubilization of a pectic fraction rich in nonesterified galacturonic acids from the primary wall. Our results also indicate that in the secondary wall of Nitella, the pectic polysaccharides could be closely joined by covalent crosslinking. Keywords: pectin, gold labelling, monoclonal antibody, ionic exchange, Nitella.
Ultrastructure of the melanized ascospores of Corollospora fusca
Authors: McKeown T. A. , Moss S. T. , Jones E. B. G.
Published: October 2007

Corollospora fusca is a marine ascomycete that based on light microscopy and scanning electron microscopy was previously described as possessing appendaged ascospores with fine longitudinal melanized striations and a ridged surface. Transmission and low voltage scanning electron microscope studies presented here do not support the existence of a ridged surface on the ascospore. Histochemical tests based on the reduction of silver nitrate were used at the electron microscope level to locate melanin in the longitudinal electron-dense deposits in the spore wall. Keywords: ascospores, Corollospora spp., marine fungi, melanin, ultrastructure, wall structure.
The dynamics of entanglement in the adiabatic search and Deutsch algorithms
Authors: Choy K , Passante G , Ahrensmeier D , Carrington M E , Fugleberg T , Kobes R , Kunstatter G
Published: October 2007

The goal of this paper is to study the effect of entanglement on the running time of a quantum computation. Adiabatic quantum computation is suited to this kind of study, since it allows us to explicitly calculate the time evolution of the entanglement throughout the calculation. On the other hand, however, the adiabatic formalism makes it impossible to study the roles of entanglement and fidelity separately, which means that results have to be interpreted carefully. We study two algorithms: the search algorithm and the Deutsch–Jozsa algorithm. We find some evidence that entanglement can be considered a resource in quantum computation.

PACS Nos.: 03.67.Mn, 03.67.Lx
Intrinsic decoherence effects on quantum dynamics of the nondegenerate two-photon f-deformed Jaynes–Cummings model governed by the Milburn equation
Authors: Naderi M H
Published: October 2007

In this paper, we study the influence of the intrinsic decoherence on quantum statistical properties of a generalized nonlinear interacting atom–field system, i.e., the nondegenerate two-photon f-deformed Jaynes–Cummings model governed by the Milburn equation. The model contains the nonlinearities of both the cavity–field and the atom–field coupling. Until now, very few exact solutions of nonlinear systems that include a form of decoherence have been presented. The main achievement of the present work is to find exact analytical solutions for the quantum dynamics of the nonlinear model under consideration in the presence of intrinsic decoherence. With the help of a supersymmetric transformation, we first put the model Hamiltonian into an appropriate form for treating the intrinsic decoherence. Then, by applying the superoperator technique, we find an exact solution of the Milburn equation for a nondegenerate two-photon f-deformed Jaynes–Cummings model. We use this solution to investigate the effects of the intrinsic decoherence on temporal evolution of various nonclassical properties of the system, i.e., atomic population inversion, atomic dipole squeezing, atom–field entanglement, sub-Poissonian photon statistics, cross correlation between the two modes and quadrature squeezing of the cavity field. Particularly, we compare the numerical results for three different cases of two-mode deformed, one-mode deformed, and nondeformed Jaynes–Cummings models.

PACS Nos.: 42.50.Ct, 42.50.Dv, 03.65.Yz
Response to overburden pressure of an HDPE pipe pulled in place by pipe bursting
Authors: Lapos B.M. , Brachman R.W.I. , Moore I.D.
Published: October 2007

Measurements of vertical and horizontal pipe deflections are reported for a high-density polyethylene (HDPE) pipe experiencing an increase in vertical pressure after being pulled in place using pipe bursting techniques. Three tests were conducted to measure the diameter change of a 165 mm outside diameter HDPE pipe after replacing an intact clay pipe with an external diameter of 184 mm backfilled with a poorly graded dense sand. A fourth test measured the response of the HDPE pipe after replacing an intact clay pipe with an external diameter of 128 mm. Variable pipe deflections were measured in each test, which depended on the interactions among the broken clay pipe fragments surrounding the HDPE pipe. The orientation of the clay fragments controls whether the increase in vertical pressure is transferred immediately to the HDPE pipe. In some cases, the fractured clay pipe produced a structural ring encasing the HDPE pipe, thus providing additional hoop strength. Two of the replacement tests did not record diameter changes until 100 kPa because of the interaction amongst the clay fragments. The upsize test and one replacement test recorded diameter changes from a vertical pressure of 20 kPa, because there were no interactions observed among the clay fragments.
K0of sand measured by a plane-strain apparatus
Authors: Wanatowski Dariusz , Chu Jian
Published: October 2007

Experimental results are presented in this note to study the coefficient of lateral earth pressure at rest, K0, of sand measured using a plane-strain apparatus. The data are also compared with the K0measured by triaxial K0consolidation tests. The test data show that the K0values measured for specimens prepared using the water sedimentation method vary little with the void ratio of the soil, and therefore do not agree with the K0values calculated using Jaky’s equation, which uses the peak friction angles obtained from either plane-strain or triaxial tests. The K0values measured for specimens prepared using the moist tamping method follow a linear relationship with the void ratio. However, this relationship does not agree with Jaky’s equation either. The K0values obtained from tests on the specimens prepared using the two different preparation methods are different, which may reflect the influence of soil fabrics or structures on the one-dimensional compression behaviour of soil.
Parametric finite element analyses of geocell-supported embankments
Authors: Madhavi Latha G. , Rajagopal K.
Published: October 2007

This paper presents the results from parametric finite element analyses of geocell-supported embankments constructed on weak foundation soils. A composite model is used to numerically simulate the improvement in the strength and stiffness of the soil as a result of geocell confinement. The shear strength of the geocell-encased soil is obtained as a function of the additional confining pressure due to the geocell encasement considering it as a thin cylinder subjected to internal pressure. The stiffness of the geocell-encased soil is obtained from the stiffness of the unreinforced soil and the tensile modulus of the geocell material using an empirical equation. The validity of the model is verified by simulating the laboratory experiments on model geocell-supported embankments. Parametric finite element analyses of the geocell-supported embankments are carried out by varying the dimensions of the geocell layer, the tensile strength of the material used for fabricating the geocell layer, the properties of the infill soil, and the depth of the foundation layer. Some important guidelines for selecting the geocell reinforcement to support embankments on weak foundation soils are established through these numerical studies.
Mechanical behaviors of a synthetic paste of tire chips and paper sludge in MSW landfill daily cover applications
Authors: Ng Kelvin T.W. , Lo Irene M.C.
Published: October 2007

A waste-derived paste of a mixture of paper sludge and tire derived aggregate (TDA) was investigated for daily cover application in municipal solid waste (MSW) landfills. The use of earth materials as daily covers not only consumes valuable landfill space, but also creates a series of operating issues. In this study, an experimental testing program was undertaken with the goal of evaluating the mechanical behaviors of the paste based on the findings of the index properties, compressibility, hydraulic conductivity, stress-induced deformation, stress–strain response, and shear resistance of the materials. The mechanical behaviors of the individual TDA, the sludge, as well as the mixture of the two, were evaluated. When compared to traditional soil covers, the proposed paste was: (i) 2–3 times lighter in weight; (ii) at least two orders of magnitude more impermeable; and (iii) comparable in shear resistance. It was also found that with the addition of TDA to the sludge, the shear strength of the paste was improved considerably. The reinforcing mechanisms were explored and quantified, suggesting an optimal TDA content of about 55% by weight. The results from this study indicate that the proposed paste has mechanical characteristics that are desirable for a potential landfill daily cover.
Continuous-Flow Cell Saver Reduces Cognitive Decline in Elderly Patients After Coronary Bypass Surgery
Authors: Djaiani George , Fedorko Ludwik , Borger Michael A. , Green Robin , Carroll Jo , Marcon Michael , Karski Jacek
Published: October 2007

Background—

Cerebral microembolization during cardiopulmonary bypass may lead to cognitive decline after cardiac surgery. Transfusion of the unprocessed shed blood (major source of lipid microparticulates) into the patient during cardiopulmonary bypass is common practice to reduce blood loss and blood transfusion. Processing of shed blood with cell saver before transfusion may limit cerebral microembolization and reduce cognitive decline after surgery.

Methods and Results—

A total of 226 elderly patients were randomly allocated to either cell saver or control groups. Anesthesia and surgical management were standardized. Epiaortic scanning of the proximal thoracic aorta was performed in all patients. Transcranial Doppler was used to measure cerebral embolic rates. Standardized neuropsychological testing was conducted 1 week before and 6 weeks after surgery. The raw scores for each test were converted to
Z
scores, and then a combined
Z
score of 10 main variables was calculated for both study groups. The primary analysis was based on dichotomous composite cognitive outcome with a 1-SD rule. Cognitive dysfunction was present in 6% (95% confidence interval, 1.3% to 10.7%) of patients in the cell saver group and 15% (95% confidence interval, 8% to 22%) of patients in the control group 6 weeks after surgery (
P
=0.038). The severity of aortic atheroma and cerebral embolic count were similar between the 2 groups.

Conclusions—

The present report demonstrates that processing of shed blood with cell saver results in clinically significant reduction in postoperative cognitive dysfunction after cardiac surgery. These findings emphasize the clinical importance of lipid embolization in contributing to postoperative cognitive decline in patients exposed to cardiopulmonary bypass.
Axl Mediates Vascular Remodeling Induced by Deoxycorticosterone Acetate–Salt Hypertension
Authors: Korshunov Vyacheslav A. , Daul Matthew , Massett Michael P. , Berk Bradford C.
Published: October 2007

Axl, a receptor tyrosine kinase, was recently identified as a novel candidate gene in a genetic model of salt-sensitive hypertension (Sabra rat). Our group first reported that Axl plays a significant role in vascular remodeling in response to injury. Here we investigated the role of Axl in the pathogenesis of hypertension in a deoxycorticosterone acetate (DOCA)–salt model. Hypertension was induced in Axl wild-type (Axl
+/+
) mice and Axl-deficient (Axl
−/−
) mice by uninephrectomy and DOCA-salt for 6 weeks. Controls were uninephrectomized and received tap water and regular chow ad libitum. DOCA-salt treatment increased systolic blood pressure by 25 mm Hg in both genotypes after 1 week. Systolic blood pressure remained significantly elevated in Axl
+/+
DOCA, whereas systolic blood pressure levels in Axl
−/−
DOCA mice were the same as controls at 6 weeks. DOCA-salt increased relative kidney weight and glomerular hypertrophy by 40% compared with controls in both genotypes. Consistent with levels of systolic blood pressure, endothelium-dependent vasorelaxation was impaired in Axl
+/+
DOCA mice compared with Axl
+/+
controls, whereas in Axl
−/−
DOCA mice relaxation responses were similar to Axl
−/−
controls. In addition, endothelium-independent vasorelaxation was improved in Axl
−/−
DOCA mice compared with Axl
+/+
DOCA mice. Nitrotyrosine and phospho-Akt immunoreactivity was significantly reduced in arteries from Axl
−/−
DOCA mice compared with Axl
+/+
DOCA mice. The remodeling index of the mesenteric artery (media:lumen ratio) was significantly increased in Axl
+/+
DOCA mice compared with Axl
−/−
DOCA mice. Finally, increased vascular apoptosis in the Axl
−/−
DOCA mice suggests a likely mechanism for Axl-dependent effects on hypertension. These data strengthen the pathogenic role for Axl in salt-sensitive hypertension.