bluuebunny/crossref_metadata_2025_split huggingface dataset:
Spatio‐temporal analysis of climate–tree ring relationships
Authors: TESSIER L. 
Published: April 2006

summaryThis paper is concerned with the value of the ecological information provided by response functions. Two questions are considered. The first deals with the spatial reproducibility of response functions depending on the tree population and the location of the meteorological station that yielded the climatic data. The second concerns the temporal stability of the response function. The climate–ring‐width relationships are calculated for six Populations of Pinus silvestris (L.). Twelve meteorological stations are involved in this calculation, over the period 1890–1980, divided in five sequences of 50 years. Analogies and differences between response functions are investigated using multi‐dimensional analysis (principal component analysis and cluster analysis).Spatial analysis reveals that the climate ring‐width relationship mainly depends on the population habitat. The temporal analysis shows that instability is linked with the evolution of the habitat, more especially with the expansion of the forest cover.
Interglacial pollen and plant macrofossils from Langdon River, western Tasmania
Authors: COLHOUN ERIC A. , VAN DE GEER GUUS , HILL ROBERT S. , BIRD TREVOR 
Published: April 2006

summaryPollen and plant macrofossils from Langdon liner give an interglacial floral record for western Tasmania. The location of the site between the ice limits of the Last or Margaret Glaciation and the Penultimate or Henty Glaciation indicate that it cannot be younger than the Last Interglacial. The sequence of vegetation changes shows the succession Casuarina Phyllocladus‐Nothofagus with Casuarina as pioneer and Nothofagus as representing Maximum wet forest development. After the maximum the presence of Phyllocladus‐Nothofagus‐Eucalyptus‐Microstrobos suggests deterioration to subalpine woodland/shrubland, and Compositae, Gramineae‐Microstrobos to alpine shrubland and herbland. The sequence represents most of a glacial‐interglacial‐glacial cycle Of environmental changes that occurred before 43 000 14C yr B.P.Very high Casuarina values occur in the early part at the interglacial sequence which contrasts with the Holocene where Eucalyptus is more important than Casuarina. Otherwise the sequence of Phyllocladus, Nothofagus, Eucryphia‐Anodopetalum is the same as for Holocene forest development. The interglaeial ‘optimum’ is marked by the occurrence of Pomaderris apetala type and Dicksonia antarctica.There is some similarity with the Casuarina curves in the Lake George interglacials before the Last Interglacial. But, on the whole, there is more similarity with interglacial rainforest development in western South Island, New Zealand Only one cycle of vegetation change is recognized at Langdon River which is unlike New Zealand and central Chilean records from 40‐42° S which in different ways record a mid Last Interglacial climatic deterioration.
Changes in ultrastructure of Golgi apparatus during the cell cycle in a synchronous culture of Catharanthus roseus
Authors: HIROSE S. , KOMAMINE A. 
Published: April 2006

summaryChanges in the ultrastructure of the Golgi apparatus during the cell cycle were investigated using a highly synchronized cell division system in a Catharanthus roseus (L.) G. Don suspension culture. During the G2 phase and cytokinesis, diameters of the dictyosomes and the number of cisternae significantly increased. Electron micrographs of cells in cytokinesis suggested that dictyosomes were dividing into two. Numerous secretory vesicles were associated with the dictyosomes in cells of the second G1 phase, the time when cell wall synthesis is most active. Structural changes in the Golgi apparatus are discussed in relation to the cell cycle and changes in cell wall synthesis.
Glutamine synthetase isoforms in the green hydra symbiosis
Authors: REES T. A. V. , SHAH N. , STEWART G. R. 
Published: April 2006

summaryThe occurrence of glutamine synthetase isoforms in the green hydra symbiosis has been investigated using ion‐exchange chromatography. There were three isoforms which were designated algal cytosolic, chloroplastic and host isoenzymes. Comparison of the proportions of algal isoforms from the intact association with those from nitrogen‐replete and nitrogen‐starved cultures of a Chlorella strain originally isolated from green hydra, suggests that symbionts in the intact association may be nitrogen‐deficient.
Some relationships between leaf anatomy and photosynthetic characteristics of willows
Authors: PATTON LINDA , JONES MICHAEL B. 
Published: April 2006

summaryThe photosynthetic light response curves and stomatal conductance of four cultivars of Salix viminalis, S. burjatica and S. × dasyclados were measured using leaves growing on unshaded plants from the field. Light saturated rates of net photosynthesis (Pn, max) ranged from 13.9 to 22.5 μ mol m−2 s−1. Cultivars of S. viminalis had the highest values of Pn. max but the lowest stomatal conductances, and as a consequence they also had the highest water use efficiency.Observations on anatomical characteristics of leaves used for photosynthesis measurements indicated a significant positive correlation between Pn. max and the ratio of the exposed surface area of mesophyll cells to leaf surface area (Ames/A) and chlorophyll content, and a significant negative correlation between Pn, max and area of fully expanded leaves.These observations show that there are a number of selection criteria based on both physiological and anatomical measurements which may be used to select for potentially high yielding willows.
The time‐course of disease suppression and antibiosis by the ectomycorrhizal fungus Paxillus involutus
Authors: DUCHESNE LUC C. , PETERSON R. L. , ELLIS BRIAN E. 
Published: April 2006

summarySeedlings of Pinus resinosa Ait. grown in test tubes were inoculated with the ectomycorrhizal fungus Paxillus involutus Fr. and, one day later, with a spore suspension of the root pathogenic fungus Fusarium oxysporum Schlecht emend, Sny. & Hans f.sp. pini. Controls consisted of seedlings inoculated with plugs of sterile modified Melin Norkrans medium and F. oxysporum. Seedling survival was counted, sporulation of F. oxysporum was measured, and ethanol extractions of the rhizosphere were made, 1, 2, 3, 4, 5, 6, 8, 10 and 14 d after inoculation with the pathogen. The ethanol extractives were concentrated and assayed for fungitoxic activity by measuring the germination of F. oxysporum microconidia. Dead seedlings were first observed 3 d after inoculation with the pathogen. Sporulation of F. oxysporum was reduced significantly 3 d after seedling inoculation with P. involutus when compared with controls lacking P. involutus. The fungitoxic activity of the rhizosphere of the seedlings inoculated with P. involutus was greater than the fungitoxic activity of the rhizosphere of control seedlings, increasing strongly 2.4 d after inoculation with the pathogen. Suppression of Fusarium root rot by P. involutus may, therefore, be the result of antibiosis by this ectomycorrhizal fungus.
Spatial dynamics and interactions of the woodland fairy ring fungus, Clitocybe nebularis
Authors: DOWSON C. G. , RAYNER A. D. M. , BODDY LYNNE 
Published: April 2006

summaryThe extension rates of Clitocybe nebularis (Batsch ex Fr.) Kummer strains on 2% malt agar were only 30–40%, of those, up to 3.4 mm d−1, observed in woodland at equivalent exponential mean temperatures. Extension of mature field systems was accomplished by mycelial annuli or arcs 30‐40 cm wide, differentiated into a leading edge of mycelial cords followed by a zone of dense, diffuse mycelium which bleached litter components, and a trailing edge of greyish, Used mycelium. Disruption of mature annuli by natural obstacles or experimental re‐orientation within the mycelial band resulted in regression of the affected segment of mycelium. Localized lysis following encounter with an obstacle by immature patches of mycelium with a diameter of 30–50 cm, led to polarized development of the residual mycelium.Strains from different fruit bodies were somatically compatible when paired on 2% malt agar if sampled from the same ring, but incompatible if from different rings, resulting in mutual antagonism and formation of a persistent demarcation zone. By contrast, collision between adjacent systems in woodland culminated in mutual obliteration of the interaction fronts. C nebularis was non‐combative when paired against other decomposer basidiomycetes on 2% malt agar, being either replaced or deadlocked but not replacing mycelia of these fungi.The implications of these observations are discussed in terms of emerging concepts of ecological strategies, foraging theory and polarity in mycelial collectives.
Glandular trichomes and essential oils in developing peppermint leaves
Authors: MAFFEI MASSIMO , CHIALVA FRANCO , SACCO TOMMASO 
Published: April 2006

summaryThe trichome number and the variability in mono and sequisterpene distribution of peltate trichomes within a leaf was investigated during development of peppermint (Mentha×piperita L.) leaves. A larger number of peltate trichomes was initiated on adaxial epidermises than abaxial epidermises, but during leaf development a greater gland number was produced on abaxial epidermises. Evidence showed that the trichome number was not fixed at the time of leaf emergence. On both epidermises, the trichome distribution was found to change with its position on the leaf. A striking monoterpene composition variability was present among individual trichomes and between different parts of the leaf. Different rates of peltate trichome development and distribution as well as significant differences in trichome number and density were found between the epidermises. A clear and opposite trend was found between menthone and menthol percentages during development. Menthone and menthol were also found to be present in larger amounts on adaxial epidermises, whereas neomenthol and isomenthol had highest percentages on abaxial epidermises. Of the total oil collected from peltate trichomes, 60%, was composed of menthone. isomenthol, menthol and neomenthol and of the remaining 40 %, more than half was represented by other mono and sesquiterpenes while the final percentage was made up of a few unidentified early eluting compounds of high Volatility.
Responses of Cynoglossum officinale L. and Senecio jacobaea L. to various degrees of defoliation *
Authors: PRINS A. H. , VERKAAR H. J. , VAN DEN HERIK M. 
Published: April 2006

summaryEffects of various degrees of defoliation on Cynoglossum officinale and Senecio jocobaea were studied under favourable growing conditions. Regrowth was found in both species, but did not overcompensate for defoliation. The physiological mechanisms responsible for regrowth after defoliation were found to relate either to an increase in net assimilation rate or to an increase in relative investment in aboveground parts. The morphological mechanism behind regrowth involved an increase in leaf area ratio. In almost completely defoliated plants, a combination of both mechanisms was found. The time needed to re‐establish the same amount of biomass as control plants differed between the species and between levels of defoliation. These differences in recovery time after defoliation are discussed in relation to decrees of herbivory found m natural situations.
The control of the cell cycle in microbial symbionts
Authors: Hill D. J. 
Published: April 2006

summaryThe development of the photosynthetic microbial symbionts of lichens and Azolla are compared. Both have more rapidly dividing cells at the growing point and slower rates of cell division in the mature regions of the host symbiont. Cell size, numbers and differentiation (function) were studied in these different stages of development. Anabaena cell number in the mature leaf cavities of Azolla increases more or less linearly. When fern growth was stopped with cycloheximide treatment, cell division in Anabaena at the apex was also arrested. In lichens, photobiont cell size increases with thallus age, us does Anabaena in Azolla. Lichen photobiont cells became larger in slower growing thalli. The pattern of photosynthetic carbon and nitrogenase functions change during thallus development. These observations together with others are used to suggest two separately operating controls on the symbiotic cell cycle: (1) nutrient supply for cell maintenance and cell growth; (2) constraint or stimulation of commitment to divide. The separate operation of these controls leads to symbiont cells being in two possible states: (1) phase I which are generative cells associated with growing host tissues and (2) phase II which are differentiated cells in the mature regions of the host.
Functional aspects of phosphorus uptake and carbon translocation in incompatible ectomycorrhizal associations between Pinus sylvestris and Suillus grevillei and Boletinus cauipes
Authors: FINLAY R. D. 
Published: April 2006

summary Pinus sylvestris L. and Larix eurolepis Henry seedlings were grown together in non–sterile laboratory microcosms containing functional mycelial networks of one of three different ectomyeorrhizal Fungi. The fungi used were Suillus bovinus (Fr.) O. Kuntze, and two Fungi which are commonly considered to be specific to Larix spp., Suillus grevillei (Klotzsch) Sing, and Boletirms cavipes (Opat.) Kalchbr. Patterns of mycorrhizal infection, transport of labelled assimilate and phosphorus uptake within the microcosms were studied in order to evaluate tine functional attributes of associations formed between P. sylvestris and the two‘larch specific’fungi. Fungal colonization of lateral roots and accumulation of labelled assimilate from adjacent plants fed with 14CO2 was significantly greater in the roots of Pinus plants when the ectomycorrhizal fungus was S. bovinu, and significantly greater in Larix roots when the fungus was V. grevillei or li. cavipes. Kctomycorrhizas formed between P. sylvestris and Ii, cavipes were fully functional in terms of transfer of labelled assimilate to the fungal mycelium. In mixed communities infected by B. caripes, myeclial uptake and translocation of 32P‐labelled orthophosphate was significantly greater to Larix plants than to Pinus plants. Formation of sheathed lateral roots on the Pinus plants was low. There was some autoradiographic evidence of phosphorus translocation from mycorrhizal pine roots to stem and leaf tissue hut levels of activity in the shoots were low, indicating limited translocation across the host‐fungus interface.
Infectivity and effectivity of indigenous vesicular‐arbuscular mycorrhizal fungi from contiguous soils in southwestern Wyoming, USA
Authors: HENKEL T.W. , SMITH W. K. , CHRISTENSEN M. 
Published: April 2006

summaryIn a greenhouse experiment, the degree of infectivity as well as effects on shoot hiomass, phosphorus concentration, and drought response in Agropyron smithii Rydb. were compared for species assemblages of vesicular‐arbuscular (VA) mycorrhizal fungi. Assemblages were collected from dissimilar soils across a 55 m elevational gradient in the xeric sagebrush‐steppe of southwestern Wyoming. Collection sites and soils were designated as ridgetop (RT), midslope (MS), and base (B|. All assemblages of mycorrhizal fungi were tested in their parent soils as well as the other two soils. In the phosphorus (P)‐deficient (10 mg kg −1) RT soil, the indigenous mycorrhizal fungi produced significantly greater concentrations of P in the shoot of the host ((0‐335 °) than did the fungi from the B site (0‐250%). In the non‐mycorrhizal plants the concentration of P in the shoot was 0.185%. The RT fungi also generated the highest levels of infection, plus greatest arbuscule and vesicle production in both the RT and MS soils. The B soil had the highest available 1’content (51 mg kg ‐1) and mean shoot P concentrations were not significantly different among plants of the different treatments grown in this soil. Inefectivity was also reduced in the B soil. This reduction in mycorrhizal activity was attributed to the high‐P availability in the H soil. Although shoot dry weight was either unaffected or possibly reduced by mycorrhizas in all soils, stomatal response to drought was not affected by mycorrhizas m any of the soils. The greater effectiveness of the RT inoculum for increasing P concentration in the shoot of A. smithii when grown in the RT soil, as well as the greater infectivity of this inoculum, may indicate adaptation in these mycorrhizal fungi to low‐P soil conditions. The relatively low infectivity and effectivity of the B fungi in the RT soil also suggests that these fungi may be less adapted to low‐P soil conditions. Thus, differences in ineffectivity and effectivity may occur among native VA mycorrhizal fungi when the parent soils are dissimilar yet contiguous.
Effect of different inocula of vesicular‐arbuscular mycorrhizal fungi on manganese content and concentration in red clover (Trifolium pratense L.) plants
Authors: ARINES J. , VILARIÑO A. , SAINZ MARIA 
Published: April 2006

summaryThree sterilized acid soils were inoculated with vesicular‐arbuscalar (VA) mycorrhizal fungi. Inocula consisted of mixtures of line + coarse type endophytes (Glomus tenue(Greenall) Hall plus either G. mosseae (Nicol and Gerd), G. fasciculatum (Thaxter sensu Gerd) Gerdemann and Trappe, G, epigaeum Daniels and Trappe or G. macrocarpum Tul and Tul var. geosporum, and native inocula). Red clover (Trifolium pratense L.) was seeded in pots and grown in a glasshouse for four months, Root colonization by VA mycorrhizal fungi, plant growth and Mn content and concentration in shoots and roots, were studied. Mycorrhiza depressed the Mn concentration in shoots and roots of plants growing in all three soils, and the Mn uptake in one of them. On average, Mn concentration in mycorrhizal plants was 45% in shoots and 20% in roots of that found in non‐mycorrhizal controls.
Cell wall bound‐phenols in roots of vesicular‐arbuscular mycorrhizal plants
Authors: CODIGNOLA A. , VEROTTA L. , SPANU P. , MAFFEI M. , SCANNERINI S. , BONFANTE‐FASOLO P. 
Published: April 2006

summaryThis paper examines the qualitative and quantitative chemical composition of phenols occurring in the cell wall of vesicular‐arhuscular (YA) mycorrhizal and non‐mycorrhizal roots of Allium porrum L. and Ginkgo bilnba L. their localization at the cellular level, and the phenylalanine ammonia lyase (PAL) activity of these tissues. Constitutive phenols occurred in both species of plants, and did not change when the symbiont Cully colonized the roots. Cell wall bouncl‐phenols were more abundant in A. porrum than in C. biloba, and PAL activity was higher too. Tyrosol, 2‐(4‐hydroxyphenyl ethanol), was identified as the most abundant component in A. porrum, where it occurred with vanillic, syringic and ferulic acids. In G. biloba, p‐coumaric, protocathecuic, vanillic and ferulic acids were found. Cell‐wall bound phenols (revealed by UV fluorescence and by transmission electron microscopy) were localized in the epidermal and hypodermal cells, but did not usually occur in the cortical cells, where the fungus developed arbuscules.We show that cell wall bound‐phenols are constitutive compounds in leek and in ginkgo:, and that the VA mycorrhizal fungus does not activate metabolic pathways leading to the synthesis of new phenols as antimicrobial substances, at least in the host cell walls.
Sensitivity of white clover to ambient ozone in Switzerland
Authors: BECKER K. , SAURER M. , EGGER A. , FUHRER J. 
Published: April 2006

summaryOzone (O3) in ambient air was investigated as a possible cause of visible damage to leaves of white clover (Trifolium repens L.) in agricultural areas of Switzerland. Differences in the sensitivity of five commonly mown cultivars were studied, namely Ladino Sacramento, Ladino California, Alban, Sonja and Milkanova. Plants were grown in pots and exposed to O3 using three different experimental systems: (i) exposure to ambient air, (ii) exposure in open‐top chambers to filtered air, unfiltered air, or unfiltered air to which O3 was added from 09.00 until 17.00 h during a four‐day period, (iii) exposure under controlled environmental condition to filtered air with or without O3 added daily. Occurrence of injury symptoms on field‐grown plants was recorded during the summers of 1987 and 1988.Ozone exposure produced visible injury expressed as small necrotic flecks on the tipper leaf surface. Irrespective of the experimental system used, the following order in O3 sensitivity was observed: L. Sacramento ≤ L. California ≪ Alban ≤ Sonja ≤ Milkanova. Injury symptoms were seen when plants were exposed to ambient O3 or to unfiltered air in open‐top chambers, but not in charcoal‐filtered air. In ambient air, symptoms in the most sensitive cultivars appeared after episodes with 1‐h maximum concentrations of above 120‐140μg m−3 occurring on several consecutive days. The symptoms of injury could be reproduced in controlled‐environment fumigation experiments using concentrations comparable to those observed in ambient air.Plants of the different cultivars grown under controlled environmental conditions did not differ in superoxide dismutase or peroxidase activity, or in the content of fructose, sucrose or glucose. Differences in O3−sensitivity between cultivars were related to differences in stomatal density and to some degree to the length of the stomatal pore. Stomatal densities were related to leaf conductance, transpiration, and rate of water loss by excised leaves. Leaves of Milkanova (resistant) had higher 313values than L. California (sensitive). Compared with filtered air, exposure to unfiltered ambient air or O3–amended air in open‐top chambers caused a change in δ13 value in leaves of L. California (sensitive), but not in leaves of Milkanova (resistant).It is concluded that ambient levels of O3 in Switzerland can be sufficient to produce visible leaf injury in sensitive white clover cultivars characterized by a high gas‐phase conductance of the leaves, that the isotopic composition of leaf tissue could be used as an indicator of O3 sensitivity in different cultivars, and that ambient levels of O3 can change the isotopic composition of the leaf tissue in sensitive species.
The potential for evolution of tolerance to sodium chloride, calcium chloride, magnesium chloride and seawater in four grass species
Authors: ASHRAF M. , MCNEILLY T. , BRADSHAW A. D. 
Published: April 2006

summaryTo examine the contrasting genetic potentials of different species, which would allow or prevent the evolution of tolerance to naturally saline environments, the growth of selected tolerant and normal lines of Agrostis stolonifera L., A. capillaris L., Holcus lanatus L., and Lolium perenne L., in NaCl, CaCl2, MgCl2 and seawater solutions was examined.NaCl tolerant lines of all four species had significantly greater root growth in NaCl, CaCl2, solutions, and seawater than unselected lines, but in MgCl., only the NaCl tolerant lines of H. lanatus had significantly longer roots than the unselected line.Screening of seedlings in solution culture in all four species, for tolerance to the same salt solutions, suggested that variability was available in each species for enhanced tolerance to each salt. When the selected material was tested as adults, the superior tolerance in response to increased seawater concentration remained for all lines in all species except those of A. capillaris and H. lanatus.The results suggest that all four species have genetic potential for the evolution of salt tolerance. The failure of some of these species to evolve salt tolerant populations in nature is likely to be due to other factors in naturally saline environments, for which the necessary adaptive genetic potential is lacking.