bluuebunny/crossref_metadata_2025_split huggingface dataset:
The history and vegetation dynamics of a yew wood (Taxus baccata L.) in S.W. Ireland
Authors: MITCHELL F. J. G. 
Published: April 2006

SUMMARYReenadinna Wood is one of the largest Taxus baccata dominated woods in the British Isles. It is therefore of considerable ecological and conservation interest. To investigate the history and dynamics of the wood, pollen data from a small hollow within the wood are described. These data are compared with the regional pollen record and local historical and archaeological information. The yew wood appears to have developed at least 3000, but probably 5000 years ago from a wood previously dominated by pine, oak, elm and hazel. There is evidence to suggest that the wood has been disturbed by periods of patch cultivation and site occupancy.
Uptake of amino acids by the cyanobacterium Anabaena ATCC 27893
Authors: PING XU , MCAULEY P. J. 
Published: April 2006

summaryActive uptake of phenylalanine has been characterized in a species of cyanobacterium, Anabaena sp. ATCC 27893. Phenylalanine was apparently taken up by only one transport system over the concentration range 2–50 μM. Inhibition of phenylalanine uptake by glutamate and a range of neutral amino acids suggested that these were internalized by the same system. At least one other system appeared to be present, transporting the basic amino acids arginine and lysine. The Km and Vmax of phenylalanine uptake were comparable to those of phenylalanine uptake in eukaryotic unicellular freshwater algae. Uptake was energy dependent and internalized phenylalanine was rapidly incorporated into trichloracetic acid‐insoluble material.
Extracellular hexacyanoferrate III inhibits cytoplasmic streaming in the algaLamprothamnium papulosum
Authors: THIEL GERHARD , KIRST GUNTER O. 
Published: April 2006

summaryInternodal cells of the euryhaline charophyteLamprothamnium papulosumexhibited a transient slow down of the cytoplasmic streaming when transferred to a medium containing hexacyanoferrate III (HCF III). The reduced form, hexacyanoferrate II, was without effect. The extent of the streaming inhibition, which appeared with a time lag of ≃ 3 min after addition of the redox reactant, was a function of the HCF III concentration. The inhibition could be prevented by preconditioning cells in the Ca2+‐channel antagonist LaCl3or by lowering the Ca2+concentration in the external medium even though these treatments did not greatly affect the rate of extracellular HCF III reduction. We therefore conclude that HCF III generates a Ca2+influx into the cytoplasm. The resulting transient increase in cytoplasmic free Ca2+inhibits the Ca2+‐sensitive streaming mechanism. Streaming inhibition was observed in acid (pH 55) and alkaline (pH 8) media. Because HCF III induced only a marked depolarization in alkaline medium, Ca2+influx is not a consequence of a decrease in transmembrane voltage.The treatments that protected cytoplasmic streaming from inhibition by HCF III did not affect the decrease in membrane resistance caused by the redox reactant. Ca2+influx is therefore unlikely to be a major mechanism by which HCF III affects membrane transport pathways.
Influence of a potassium‐channel blocker and metabolic and ATPase inhibitors on potassium and malate content of Phaseolus coccineus L. pulvini
Authors: BIAŁCZYK JAN , LECHOWSKI ZBIGNIEW 
Published: April 2006

summaryThe effect of the K+ channel blocker tetraethylammonium chloride (TEA‐C1), of non‐specific ATPase inhibitors (dicyclohexylcarbodiimide and diethylstilbestrol) and of the uncoupler, carbonyl cyanide‐m‐chloro‐phenyl‐hydrazone (CCCP) on the contents of K+ and malate was investigated in the intact motor system of Phaseolus coccineus pulvini. The results suggest that in these conditions the activity of K+‐channels in motor cells of extensor and flexor parts is limited. Treatment of detached leaves with 20 mol m−3 TEA‐C1 completely blocked K+ and malate movement and also limited the K+ flux between the opposite parts of the pulvinus. In these conditions K+ and malate contents in the two parts of the pulvinus was reduced in both phases of the diurnal cycle as compared with the control (plants treated with potassium iminodiacetate). A similar effect was found when the activity of the proton pump was decreased by H+‐ATPase inhibitors or CCCP. The transport of potassium and the effect of its content on the level of malate in motor cells of Phaseolus coccineus pulvinus were also investigated.
Role of light in the biosynthesis and turnover of photosynthetic fructose‐1, 6‐bisphosphatase in pea (Pisum sativum L.) seedlings
Authors: SAHRAWY M. , CHUECA A. , HERMOSO R. , LÁZARO J. J. , GORGÉ J. LÓPEZ 
Published: April 2006

summaryPhotosynthetic fructose‐ 1, 6‐bisphosphatase (FBPase) determined immunologically by ELISA undergoes a sharp increase when etiolated pea (Pisum sativum L. cv. Lincoln) seedlings are illuminated for 24 h. The rise of enzyme activity appears slower than that of FBPase protein, which means an earlier synthesis of a precursor or some other immunologically related but inactive form of the enzyme. A second possibility is a delayed synthesis of a factor – i.e. a component of the ferredoxin‐thioredoxin activation system – necessary for the expression of the enzyme activity. With more extended illumination times, the highest FBPase content, as well as maximum activity, was obtained after 4 d of light exposure, the former representing 0.66 % of the total soluble protein. After that time, a decrease of both FBPase protein and enzyme activity was observed, probably as a consequence of a premature senescence promoted by such an extended and continuous light exposure. A maximum FBPase labelling was obtained at 6.5 h after leaf application of a [35S]methionine pulse to etiolated pea seedlings, which were then continuously illuminated. From the pattern of the radioactive decay of FBPase labelling, a half‐life of 14 h was calculated for this photosynthetic enzyme.
Extension growth in a barley mutant with reduced sensitivity to low temperature
Authors: POLLOCK C. J. , TOMOS A. D. , THOMAS A. , SMITH C. J. , LLOYD E. J. , STODDART J. L. 
Published: April 2006

summaryThe ‘slender’ mutant of barley (Hordeum vulgare) shows high rates of leaf extension and a reduced temperature threshold for extension growth compared with normal seedlings. The turgor pressure of epidermal and mesophyll cells within the extension zone was unaffected by localized cooling. Measurements of linkage patterns in cell wall carbohydrates isolated from the extension zone showed no variation with genotype or growth temperature, suggesting that the gross chemical architecture of the cell walls was similar.Differences between genotypes were observed when the rheological properties of extending leaves were measured using an extensiometer. Leaves from mutant seedlings showed greater plastic deformation than those from normal seedlings. These differences were absent in mature leaves or in growing leaves killed in boiling methanol prior to measurement. Differences were observed in the patterns of autolytic release of carbohydrates from cell wall extracts, in the incorporation of radioactivity from14CO2into specific components of the extending cell wall and in the amounts of uronic acids released following treatment with pectolytic enzymes. These results are discussed in relation to the hypothesis that the mutation acts by modifying the patterns of turnover of structural components in the extending cell wall, thereby affecting extensibility.
Stamen ontogeny in the temperature‐sensitive ‘stamenless‐2’ mutant of tomato (Lycopersicon esculentum L.)
Authors: POLOWICK P. L. , BOLARIA R. , SAWHNEY V. K. 
Published: April 2006

summaryIn the temperature‐sensitive ‘stamenless‐2’ (sl‐2/sl‐2) mutant of tomato (Lycopersicon esculentum L.), normal‐looking stamens are produced under low temperatures, but under high temperature conditions carpelloid stamens develop. Under low temperature conditions, the mutant stamens follow a pattern of development comparable to the normal (+/+) stamens in all respects, e.g. initiation, locule formation and hair production. The ontogeny of carpelloid stamens under high temperature conditions diverged from that of the normal and low temperature‐grown mutant stamens at an early stage of development (<0.2 mm), and followed a sequence of development similar to that of the apocarpous gynoecia of other species.
Ozone effects on the fatty acid composition of loblolly pine needles (Pinus taeda L.)
Authors: FANGMEIER A. , KRESS L. W. , LEPPER P. , HECK W. W. 
Published: April 2006

summaryLoblolly pine trees were fumigated with ozone in open‐top chambers and the fatty acid content of the needles was analysed. Fatty‐acid composition depended on needle age. Ozone effects also differed with needle age. In needles treated during the needle elongation period, ozone fumigation decreased the C18:3 and increased the C18:2 and C18:1 content. In needles already elongated before ozone treatment was initiated, fatty acid content decreased. The results suggest different pathways of ozone attack in elongated and elongating needles. No differences in response to ozone were found for fatty acids in needles of four different half sib families.
Antagonistic interactions involving plant pathogens: fitting and analysis of models to non‐monotonic curves for population and disease dynamics
Authors: GILLIGAN C. A. 
Published: April 2006

summaryNonlinear models were fitted to selected data sets, obtained from published papers, in which inoculum of a fungal plant pathogen or microbial antagonist of a pathogen increased and then decreased with time. Conventional models that have been widely used in botanical epidemiology, such as the logistic, monomolecular and Weibull functions, could not be fitted to these non‐monotonic curves. Two models, the over‐damped in which Y=A+B exp (α1t +C exp (α2t), and the critically damped in which Y=A+ (B+Ct) exp (–λt), were fitted: Y is a measure of the pathogen or antagonist, t is time, A is an asymptote, B and C are locational parameters and α1, 2 and λ are rate parameters. These models are standard solutions of a second order differential equation. They have a single cycle, involving a rise and subsequent decline in the population density of the micro‐organism which ultimately tends to an asymptotic equilibrium. The over‐damped model was successful only in fitting large data‐sets and was used to describe the population dynamics of bacterial colonization of live‐ and heat‐killed conidia of Cochliobolus sativus (Ito & Kurib.). Drechs. ex Dastur as well as the population dynamics of Laetisaria arvalis Burdsall in untreated and in pasteurized soil with and without subsequent reinfestation with Pythium ultimum Trow. The critical damping model was used to describe pre‐emergence damping‐off of Rhizoctonia solani Kühn in successive crops of radish, the population dynamics of P. ultimum and low‐temperature Pythium spp. in untreated soil and pasteurized soil with L. arvalis, the population dynamics of Trichoderma viride Pers. ex S. F. Gray in plant growth media and, similarly, of Macrophomina phaseolina (Maub.) Ashby in soil and, lastly, the colonization of organic fragments by P. ultimum with and without antagonism from P. nunn Lifshitz, Stanghellini & Baker. The selected model was first fitted to the empirical progress curve for each treatment. Subsequently one or more common parameters were constrained to fit all treatments while the remaining parameters were fitted separately. None of the treatments affected the rate parameters but treatments did affect the asymptote and locational parameters. The shapes of the models are discussed in relation to initial amounts of inoculum, the initial rate of increase of inoculum and the time to achieve maximum levels of disease or microbial biomass. The over‐damping model is shown to represent the solution of a set of simple linked differential equations for two interacting populations. The derivation of these elementary models is discussed in relation to the study of biological control of plant pathogens.
Cryopreservation of spores of vesicular–arbuscular mycorrhizal fungi*
Authors: DOUDS DAVID D. , SCHENCK N. C. 
Published: April 2006

summaryStorage of spores of vesicular‐arbuscular (VA) mycorrhizal fungi in soil at 5 °C is a common way of preserving these fungi. This method was satisfactory for Glomus intraradix Schenck & Smith but not for Gigaspora margarita Becker & Hall, Glomus mosseae (Nicol. & Gerd.) Gerdemann & Trappe, and Acaulospora longula Spain & Schenck. Preservation of spores at −60 to −70 °C was examined. Cryoprotectants such as DMSO, glycerol, mannitol, and sucrose were ineffective using the freeze‐damage sensitive species G. margarita. Incubation for 47 h in 0.75 to 1.0 M trehalose conferred a measure of freeze damage protection to the spores such that germination rates of previously frozen spores of G. margarita were one tenth to one sixth of controls. The best method of cryoprotection and cryopreservation was found to be slow drying of pot culture soil and freezing the spores in situ. This procedure was satisfactory for the five genera of VA mycorrhizal fungi evaluated.
Effects of liming on ectomycorrhizal fungi infecting Pinus sylvestris L.
Authors: ERLAND SUSANNE , SÖDERSTRÖM BENGT , ANDERSSON SOLBRITT 
Published: April 2006

summaryGrowth rates of ectomycorrhizal fungi were measured in pure culture at pH 3–8 on MMN‐agar and sterilized peat, with and without nutrients added. Mycorrhizas were synthesized with Pinus sylvestris L. seedlings and the growth rate of the external mycelium was measured in peat at pH 3.8 and 7.3. The fungi were three isolates of Piloderma croceum Erikss. & Hjorts., two isolates of an unidentified (pink) mycorrhizal type and one isolate of another unidentified (white long) mycorrhizal type, all isolated from P. sylvestris roots.All three fungi showed much higher (2–5 times) growth rates when grown as symbionts than when grown in pure culture. The P. croceum isolates also grew as symbionts at pH 7.3, where no growth occurred in pure culture. These findings emphasize the danger of generalizing from data obtained in pure culture studies to explain what may happen when fungi grow in symbiosis with host plants.Generally, growth rates in pure culture were higher and the pH tolerance levels were wider on agar than on peat. The exceptions were one P. croceum isolate, which had the fastest pure culture growth rate on peat with MMN, and the pink isolates, which grew at higher pH on peat than on agar. There were no significant differences between growth on peat with and without MMN.
Genetic variation in ectomycorrhiza formation byPisolithus arhizusonPinus pinasterandPinus banksiana
Authors: LAMHAMEDI MOHAMMED S. , FORTIN J. ANDRÉ , KOPE HARRY H. , KROPP BRADLEY R. 
Published: April 2006

summaryThe ability of 28 monokaryons and 78 reconstituted dikaryons ofPisolithus arhizus(Scop, pers Pers.) Rauchert [Syn.:Pisolithus tinctorius(Pers.) Coker & Couch] to form ectomycorrhizas onPinus pinaster(Ait.) Sol. andPinus banksiana(Lamb.) was studied using the growth pouch method. The ability to form mycorrhiza and promote growth ofP. pinasterdiffered both between and within monkaryons and dikaryons. Some monokaryons and dikaryons failed to form ectomycorrhizas. Monokaryons formed fewer ectomycorrhizas onP. pinasterthan dikaryons. The heterokaryotic state was necessary for the full expression of ectomycorrhiza‐forming ability. Growth ofP. pinasterwas more strongly correlated with ectomycorrhiza formation by dikaryons than by monokaryons.
The interaction of sodium and calcium chlorides and light on growth, potassium nutrition, and proline accumulation in callus cultures of Medicago sativa L.
Authors: SHAH S. H. , WAINWRIGHT S. J. , MERRETT M. J. 
Published: April 2006

SUMMARYCallus cultures, established from cultivars of Medicago sativa L., Dupuits and Spredor2, were used to investigate salt‐induced changes in metabolism. With increase in NaCl concentration there was a progressive reduction in growth rate but this effect was ameliorated by increase in the Ca2+ concentration. The concentration of Na+ in the callus increased in response to NaCl in the medium but not proportionally, while the K+ concentration was lowest in calli grown at the highest NaCl concentration. High Ca2+ partially reversed the salt‐induced decrease in K+, so overall, the effect of Ca2+ was to decrease the Na+/K+ ratio. Proline concentration in the callus increased in response to NaCl. With callus cultures grown in the absence of supplemental NaCl there was no correlation between growth and proline concentration, whereas at the highest NaCl concentration used (150 mol m−3) there was a strong positive correlation between growth and proline concentration of individual calli. Increased Ca2+increased the proline concentration in callus of both cultivars, and at the highest salt concentration resulted in higher proline concentration and increased growth. It is suggested that proline accumulation is important for cell growth only when a certain level of salt‐stress is attained, and this level will depend on the presence or absence of other protectant mechanisms in the tissue.
Seasonal variations in mineral concentrations in the trunk xylem sap of beech (Fagus sylvatica L.) in a 42‐year‐old beech forest stand
Authors: GLAVAC V. , KOENIES H. , EBBEN U. 
Published: April 2006

SUMMARYIn a 42‐yr‐old beech forest stand, growing on acid brown earth, five trees were felled every 2 wk. From their lowest trunk segments, each 100 cm in length, tracheal sap was collected by water displacement. The investigation was performed from mid‐October 1988 to mid‐October 1989, comprising a total of 130 sample trees. Xylem sap concentrations of calcium, magnesium, potassium, and manganese of 26 sampling series were analysed by atomic absorption spectrophotometry, and the pH values of fresh sap samples were determined. The seasonal variation in xylem sap concentrations of Ca, Mg and Mn in the lowest trunk sections showed a strong increase in the second half of March and in April, a decrease in May, after the leaves had expanded, a low level in summer, and a new increase in late autumn and winter. Potassium showed a different pattern with maximal xylem sap concentrations in autumn. Additionally, at four sampling dates (mid‐March, beginning of May, mid‐August and mid‐November), four trees, one at each date were cut into sections for the determination of the mineral concentrations in the xylem sap along the stem.
The growth and development of Vicia faba L. in filtered and unfiltered open‐top chambers
Authors: SANDERS G. E. , TURNBULL N. D. , CLARK A. G. , COLLS J. J. 
Published: April 2006

SUMMARYThe response of Vicia faba cv. Ticol to ambient levels of air pollutants was investigated using open‐top chambers (OTCs) ventilated with ambient air (NF treatments) and charcoal‐filtered air (CF treatments). The OTCs were placed over a conventionally drilled crop shortly after emergence in April 1988, and remained in place until after the crop was harvested in September 1988. The daily mean pollutant concentrations were 15, 7, 6 and 9 nl 1−1 for O3, SO2, NO and NO2 respectively inside NF OTCs, and 6, 3, 8 and 5 nl I−1 respectively for CF OTCs. These pollutant levels were accompanied by changes in both the vegetative and the reproductive development of V. faba. The upper leaves of plants growing in CF air expanded to larger areas than corresponding leaves on NF plants, and the canopy of CF plants intercepted more radiation than that of NF plants. At flowering, CF plants had 11 % more flowers than NF plants. This difference was maintained during early pod development and was caused by greater retention of pods on the upper racemes of CF plants. As the pods dried however, more pods were abscised from CF plants than from NF plants, and by harvest the number of pods per plant was comparable for the two treatments. Thus the observed differences in growth and development were transient and did not result in differences in final yield.
Effects of simulated acid rain on epicuticular wax production, morphology, chemical composition and on cuticular membrane thickness in two clones of Sitka spruce [Picea sitchensis (Bong.) Carr.]
Authors: PERCY K. E. , BAKER E. A. 
Published: April 2006

SUMMARYSticklings (rooted cuttings) of two Sitka spruce [Picea sitchensis (Bong.) Carr.] clones were exposed to simulated rain of 4 pH values (5.6, 4.2, 3.4, 2.6). Rain was applied at 2 mm h−1 for 1 h, three times weekly, for 11 wk starting 1 wk prior to bud break. A range of physicochemical cuticular characteristics were investigated on current‐year needles following 2, 6, and 11 wk of exposure. Cuticular effects were initiated well above the threshold for visible injury (pH 2.6). The magnitude and direction of cuticular response differed significantly between clones. Amount of epicuticular wax recovered was not affected by the pH of the simulated rain. Wax structure was greatly modified at pH ≤ 3.4 on needles from one clone. Changes in wax structure were accompanied by changes in chemical composition, formation of amorphous deposits with increasing rain acidity coinciding with decreases in nonacosane‐diols and increases in estolides. Cuticular membrane thickness was increased significantly (P > 0.001) in one clone and decreased in the other due to simulated rain pH. Such alterations to physico‐chemical cuticular characteristics would be expected to have consequential effects on needle surface properties such as needle wettability and retention of acidic rain.
The endophytic fungal community in leaves of a coastal redwood population diversity and spatial patterns
Authors: ESPINOSA‐GARCIA F. J. , LANGENHEIM J. H. 
Published: April 2006

SUMMARYLeaf endophytic fungi were isolated from 1 to 12‐yr‐old leaves of mature trees and basal sprouts of coastal redwood [Sequoia sempervirens (D. Don ex Lamb.) Endl.] in a redwood forest in Central California. Almost all samples yielded at least one species. The two most frequent species were Pleuroplaconema sp. and Cryptosporiopsis abietina Petrak. Among isolated taxa are endophytic generalists, species previously known as pathogens and a possible specialist. Species composition in leaves of progressing age in single branches revealed a patchy pattern of leaf colonization without an obvious sequence of succession. Changes in diversity and equitability in the endophytic community with leaf age are linked with differential distribution of some species in young versus old leaves and the increase in species richness in 4‐ and 5‐yr‐old leaves. The endophytic communities from leaves of trees and sprouts were generally similar, but with important differences in species richness and in distribution of Pleuroplaconema sp. and Pestalotiopsis funerea (Desm.) Stey. Principal component analysis based on endophytic frequency also indicated closeness of trees and sprouts as groups, but clearly separated each tree from its sprout. Differential susceptibility between trees and sprouts to endophytic infection is suggested on the basis of their endophytic communities.