bluuebunny/crossref_metadata_2025_split huggingface dataset:
Copper tolerance of Acer pseudoplatanus L. (sycamore) in tissue culture
Authors: TURNER ANDREW P. , DICKINSON NICHOLAS M. 
Published: April 2006

SUMMARYThe growth of Acer pseudoplatanus L. (sycamore) callus tissue on solid and liquid growth media containing elevated copper concentrations was studied in an attempt to understand the responses of trees to metal contamination and to provide an index of tolerance which may show a parallel expression of tolerance to the whole plant. Callus growth on solid media was very variable, but was significantly reduced at 10 mg l−1, with necrosis occurring at 20 mg l−1; copper was readily removed from the media in direct proportion to its concentration. Cell suspension cultures differed in their response to copper according to their site of origin. In cultures originating from uncontaminated sites, growth was inhibited at 12.5 and 15.0 mg l−1 Cu, but cultures originating from mature trees at a metal‐contaminated site were not affected by these concentrations. This metal tolerance trait was stable in cell culture through repeated sub‐culturing on uncontaminated media for periods of more than 12 months. The trait was not present in a culture derived from a (non‐tolerant) seedling at the metal‐contaminated site, but it was induced in one non‐tolerant culture by repeated exposure to high metal levels. The significance of these findings is discussed in the context of the possession of appropriate genetic variation in trees for surviving the impact of metal contamination.
Calcium amelioration of aluminium toxicity effects on root hair development in soybean [Glycine max (L.) Merr.]
Authors: BRADY D. J. , EDWARDS D.G. , ASHER C.J. , BLAMEY F. P. C. 
Published: April 2006

SUMMARYLow activities of the monomeric aluminium (Al) species, Al3+, Al(OH)2+ and Al(OH)2+ in solution reduce root growth and root hair development in soybean [Glycine max (L.) Merr.]. Calcium (Ca) ameliorates to a certain extent the toxic effects of Al on root growth, but the interactive effects of Ca and Al on root hair development are not known. In the absence of added Al in solution culture, Ca concentration over the range 500–2000 μM had little effect on root growth or root hair development of soybean cv. Fitzroy. Where the sum of the activities of the monomeric Al species was 2 μM, taproot elongation and lateral root development of soybean was suppressed in solution with 500 μM Ca. The length of the root hair zone was only 10% of that in plants not exposed to Al, and scanning electron microscopy revealed a low density of root hairs. Increasing the Ca concentration to 2000 μM largely overcame these deleterious effects. The results are discussed in relation to the role of root hairs as infection sites for Bradyrhizobium, and the known effects of Al in suppressing nodulation in soybean.
Ion distribution in relation to leaf age inLeptochloa fusca*(L.) Kunth (Kallar grass)
Authors: BHATTI A. SAEED , STEINERT SABINE , SARWAR G. , HILPERT ANDREA , JESCHKE W. DIETER 
Published: April 2006

SUMMARYUsingLeptochloa fusca(Kallar grass) plants, the distribution of K, Na, Mg and Ca between leaves of various ages has been studied. Plants grown in a salt‐affected, reclaimed field, in a solution culture and in soil in pots at 10, 100 and 125 mM NaCl have been analyzed. Despite the presence of salt‐secreting glands onLeptochloa fuscaleaves, Na concentrations increased strongly with leaf age, while K concentrations were highest in young leaves and decreased with increasing leaf age. This was due to K retranslocation, which was clearly intensified at higher external NaCl concentration. The data point to the importance of K recycling in this halophyte and also to the use of Na by this salt‐secreting species for turgor maintenance in mature and old leaves. Both Mg and particularly Ca concentrations increased with leaf age, indicating that xylem import surpassed phloem export even for the phloem‐mobile ion, Mg. In young leaves, Mg concentrations exceeded those of Ca.
Promotion of germination of fynbos seeds by plant‐derived smoke
Authors: BROWN N. A. C. 
Published: April 2006

SUMMARYFynbos is the dominant vegetation type in the Cape floristic region. Periodic fires are a natural phenomenon in fynbos and fire‐stimulated seed germination has been reported for a number of fynbos species. Amongst the factors proposed as being directly responsible for the effects of fire are: heat fracturing hard seed coats, heat stimulating seed embryos, high‐temperature desiccation of seed coats, ethylene and ammonia in smoke stimulating seed germination, and unknown chemical factors in plant‐derived smoke and smoke extracts stimulating germination. In this study 28 fynbos species were screened for a seed germination response to smoke and/or smoke extract treatments. Twelve of these species showed a statistically significant enhancement of germination in response to treatment. For the first time smokeper sehas been shown to act as a seed germination cue for fynbos species in the Asteraceae, Ericaceae and Restionaceae, and for the first time smoke extracts have been shown to enhance germination in fynbos species of Proteaceae. The most marked response to both smoke and smoke extracts was shown by seed ofSyncarpha vestita(syn.Helichrysum vestitum)(Asteraceae).
Palaeoenvironmental investigations directly associated with a neolithic axe ‘quarry’ on Beinn Lawers, near Killin, Perthshire, Scotland
Authors: TIPPING RICHARD , EDMONDS MARK , SHERIDAN ALISON 
Published: April 2006

SUMMARYA peat column containing two discrete layers of debitage from the production of neolithic axe ‘rough‐outs’ at Creag na Caillich, above Killin, Perthshire, was sampled to obtain an understanding of the environmental changes taking place at the site prior to, during and immediately after utilization of the stone resource. The column was subject to sedimentological analyses, and to ‘high‐resolution’ palynological analyses, including pollen preservation and microscopic charcoal counts. Five radiocarbon dates were obtained.The site, at 750 m OD, is thought to have been just below the tree‐line, within hazel‐birch woodland, with some elm, but close to its upper limit. Peat inception at c. 5950 cal BP is thought to have been climatic in origin, in the absence of evidence for anthropogenic activity. Slight anthropogenic modifications to the scrubby woodland, with a decline of elm, are recorded from c. 5250 cal BP, close to the lower axe debitage layer. Clearance at this time appears not to have been for grazing, but was possibly for fires. The modification of the montane grass‐heath to an ‘anthropogenic’ grassland under grazing pressure occurred later, from c. 4600 cal BP, prior to the second period of axe ‘manufacture’ at c 3800 cal BP.
Spatial diversity in the mid–Flandrian vegetation history of North Gill, North Yorkshire
Authors: TURNER JUDITH , INNES J. B. , SIMMONS I. G. 
Published: April 2006

SUMMARYThe results of investigating a series of 11 pollen and stratigraphic profiles in peats along a 350 m stream section are described. Each profile has a small pollen catchment overlapping little with its neighbour's and the diagrams therefore show fine spatial resolution of the vegetational history. Fine temporal resolution is provided by 1 cm, or for certain sections 1 mm, interval samples. There is evidence that during the Mesolithic distinct patches of the local forest vegetation, of the order of tens rather than hundreds of metres in diameter, were managed by burning and the regular lopping of branches, for periods of up to a few hundred years each. Peat inception is thought to have occurred as early as the 9th millenium BP in some parts of the stream and up to 3000 yr later in others. Lopping and burning was the immediate cause at most sites within the channel of the gill, although fine–scale topographic and geological variation affected the timing. The developing peat was bordered by an alder carr in the lower and middle reaches of the stream. Radiocarbon dating of the mid–Flandrian Ulmus decline shows it to be asynchronous. It was caused by a combination of factors including disease and the affect the mesolithic management practices had had on the soil earlier in the Flandrian.
Partial characterization of enzymes of nitrogen metabolism in Chlorella autotrophica Shihira & Krauss
Authors: AHMAD IFTIKHAR , HELLEBUST JOHAN A. 
Published: April 2006

SUMMARY Chlorella autotrophica shows a major decline in the intracellular concentrations of glutamine synthetase (GS) isoenzymes, GS1 and GS2, and a marked increase in the concentration of NADPH‐dependent glutamate dehydrogenase (GDH) when nitrate is replaced by ammonium as the sole nitrogen source. NADH‐dependent GDH shows very little change under these conditions. The apparent Km for ammonium of both GS isoenzymes is around 50 μM and that of NADPH‐GDH is around 15 mM. There is little change in the latter when the NADPH concentration in the assay medium is decreased, or when cells are harvested at different growth phases. In vitro kinetic analysis of GS1 and GS2 indicate low affinities of these isoenzymes for substrates other than ammonium. Both GS1 and GS2 require about 10 mM ATP, 20 mM Mg2+ and 70 mM glutamate for maximum activities. The rate response curves obtained for GS2 show nonlinear kinetics for glutamate and Mg2+. The double reciprocal plots for activity vs. substrate concentration for GS2 show dual kinetics with respect to glutamate concentrations, with a low Km value of about 10 mM and a high Km value of 40 mM. The rate response curve for GS2 for Mg2+ is sigmoidal. The Km values for glutamate measured for aspartate aminotransferase (AsAT) and alanine aminotransferase (AlAT) are in the same range as those measured for the two GS isoenzymes. The algal aminotransferases have very low Km values (18–55 μM) for 2‐oxoglutarate.
Purification and characterization of fructan: fructan fructosyltransferase from Jerusalem artichoke (Helianthus tuberosus L.)
Authors: LÜSCHER M. , FREHNER M. , NÖSBERGER J. 
Published: April 2006

SUMMARYFructan: fructan fructosyltransferase activity (FFT, EC 2.4.1.100) from Helianthus tuberosus L. was purified 221‐fold by a basic procedure involving ammonium sulphate precipitation, lectin chromatography and ion‐exchange chromatography. The resulting FFT preparation was separated into three protein bands, of apparent molecular weight 72800, 60 500 and 56 200, by denaturing polyacrylamide gel electrophoresis. These proteins showed affinity to sucrose‐Eupergit. FFT proteins with a molecular weight of 72800 were isolated by preparative native gel electrophoresis, and yielded six distinguishable forms on separation by analytical isoelectric focusing. Proteins from the basic purification were separated by preparative isoelectric focusing into several forms with isoelectric points between pH 4.3 and 4.5. Samples from the gel with FFT activity were analyzed by denaturing polyacrylamide gel electrophoresis. Three samples contained only protein with the molecular weight 72800, and one sample contained only protein of apparent molecular weight 60500. The remaining samples contained a mixture of proteins with molecular weights of 72800, 60500 and 56 200.FFT was detected by 1‐kestose‐dependent nystose production. The enzyme was most active at pH 65, and up to 80 % of the activity was retained on pre‐incubation (1 h) at temperatures of up to 40 °C. FFT transferred fructosyl groups from oligofructans [degree of polymerization (DP) 3–8] of the inulin series. No glycosyl transfer occurred with 6‐kestose, neokestose, maltose, raffinose and maltotriose as the sole substrate. Sucrose efficiently accepted fructosyl units from oligofructans with a Km of approximately 0.2 mM. The rate of fructosyl transfer increased with degree of polymerization (from DP 4). 1‐kestose was shown to be an efficient donor of fructosyl units to sucrose.
Comparison of protein patterns in non‐mycorrhizal and vesicular–arbuscular mycorrhizal roots of red clover
Authors: ARINES J. , PALMA J. M. , VILARIÑO A. 
Published: April 2006

SUMMARYA comparison of the protein content and patterns in root extracts from non‐mycorrhizal and vesicular‐arbuscular mycorrhizal [Glomus mosseae (Nicol. et Gerd.) Gerd. et Trappe] red clover (Trifolium pratense L.) has been made. Soluble protein content was higher in mycorrhizal than in non‐mycorrhizal roots. After separation by DEAE‐cellulose chromatography and electrophoretic analysis, several additional polypeptides appeared in mycorrhizal extracts. In addition, it seems that one of the additional proteins was a plant‐induced superoxide dismutase isozyme.
Magnetic resonance imaging of leaves
Authors: VERES JOHN S. , COFER GARY P. , JOHNSON G. ALLAN 
Published: April 2006

SUMMARYSeveral aspects of leaf anatomy and morphology make it difficult to image leaves with magnetic resonance imaging. Since most fully expanded leaves contain much intercellular air space and are often thin in one plane, relatively few water protons are available to provide signal. Their heterogeneous structure and the presence of many air‐water interfaces cause imaging problems as a result of differences in magnetic susceptibility of tissues and cells. Significant progress has been made in overcoming these difficulties, primarily by greatly reducing the echo time, permitting in vivo imaging of leaves at 7 and 9.4 Tesla with an in‐plane resolution of less than 15 μm2. Examples are shown and the potential for gaining information regarding in vivo water relations of leaves is discussed.
Rates of water uptake into the mature root system of maize plants
Authors: VARNEY G. T. , CANNY M. J. 
Published: April 2006

SUMMARYA new method of measuring water uptake by roots is applied to whole root systems of large maize plants growing in aeroponic (mist) culture. The method depends on the build‐up of concentration of dye (sulphorhodamine G) on and in the root surface, when it is fed in the mist. Water enters the roots rapidly, but the dye is separated from the water by osmotic filtration and penetrates the apoplast only by very slow diffusion. The dye accumulates progressively with time on roots on transpiring plants, but not on roots of non‐transpiring controls. The rate of accumulation of dye at a place on the root is translated to a flux of water into the root at that place, using the concentration of dye in the mist. Water fluxes were measured into first‐order branches and axes over the root system and expressed both as fluxes per unit length and per unit surface of root. Values are consistent with those found by potometric methods for limited samples of young plants. The variance of the measurements is quite large, possibly reflecting real heterogeneities in water uptake throughout the root system. The maximum water uptake achieved by a few branches was 40 μl h−1 cm−2 root. On average, flux into axes and branches was the same throughout the root system, at about 5 μl h−1 cm−2. The region of the axis at which the late metaxylem vessels mature and become conducting coincides with the region where the branches become active in water uptake (20–30 cm from the tip). Proximal to this, the branches collect about eight times as much water as the axis, having about eight times the surface area. The zone of maximum water collection by branches and axis is 30–60 cm from the tip (6–8 μl h−1 cm−1 axis). In the older, more proximal regions, water collection drops to about a quarter of this.
The taxonomic and evolutionary significance of leaf longevity
Authors: ROGERS R. W. , CLIFFORD H. T. 
Published: April 2006

SUMMARYThe half‐lives of leaves of 202 taxa of vascular plants were estimated mostly from the literature and ranged from 1 to 350 wk. The longevity of leaves in the plant groups studied is in the order Pinophyta > Pteridophyta > Liliatae > Magnoliatae. Substantial differences are evident between the superorders of flowering plants proposed by Dahlgren and the subclasses proposed by Cronquist. The mean leaf half‐life for families of Magnoliatae was shown to be inversely related to their Advancement Index. Length of life of leaves, therefore, appears to have taxonomic significance, with more primitive vascular plants tending to have longer‐lived leaves than the more advanced. The ecological significance of leaf half‐life is less clear, except in that annual leaf fall is not necessarily associated with deciduousness. The capacity to shed individual leaves may give the angiosperms a flexibility in environmental response which allows them a competitive advantage over the gymnosperms except in the most stressful habitats.
Interactions of fungi with toxic metals
Authors: GADD G. M. 
Published: April 2006

SUMMARYThis review details the major interactions of fungi with toxic metal species. Physico‐chemical and biological aspects are discussed including definitions and classification of metals in biological contexts, mechanisms of metal fungitoxicity, resistance and tolerance, environmental influences and the occurrence of fungi in metal‐polluted habitats. Cellular interactions include extracellular precipitation and complexation, binding to cell walls, transport of monovalent and divalent metal cations, intracellular fates of toxic metal species (including metal‐binding proteins and peptides, and vacuolar compartmentation), and metal transformations including organometal(loid) synthesis. Significant interactions between metals and mycorrhizal fungi and macrofungi are summarized with reference to the amelioration of plant phytotoxicity and metal accumulation respectively. Biotechnological aspects of metal‐fungal interactions relate to the biological treatment of metal‐contaminated effluents and waste streams for metal removal/recovery and environmental protection.

CONTENTS

Summary

I.
Introduction
25

II.
Definition and classification of metals
26

III.
Fungitoxicity of metals
28

IV.
Interactions between toxic metals and fungi
32

V.
Mycorrhizal interactions with toxic metals
45

VI.
Accumulation of metals by macrofungi
45

VII.
Biotechnological aspects of fungal metal accumulation
46

Acknowledgements
51

References
51

Note added in proof*
60
Identification of cytoskeletal components in pine ectomycorrhizas
Authors: TIMSONEN SARI , FINAY RROGER D. , SÖDERSTRÖM BENGT , RAUDASKOSKI MARJATTA 
Published: April 2006

SUMMARYEctomycorrhizal associations were synthesized between pine seedlings and the fungi Suillus bovinus (L.) ex Fr. or Paxillus involutus (Batsch ex Fr.) Fr. Immunoblotting of polypeptides separated electrophoretically from crude tissue extracts revealed the abundant presence of tubulin and actin in ectomycorrhiza and lower amounts in the fungal strands surrounding the ectomycorrhizal roots. In ectomycorrhiza the α‐tubulins from fungal hyphae and plant cells were clearly distinguishable but such discrimination was not possible for β‐tubulin or actin due to the similar mobility of proteins originating from the conifer and fungal tissues. Young ectomycorrhizal short roots were fixed while still attached to the seedlings and, using indirect immunofluorescence microscopy with tubulin antibodies, microtubules were detected in both the conifer cells and in fungal hyphae. In the host plant cytoplasmic and spindle microtubules were visualized in meristem cells and in differentiating vascular tissue but not in the cortical cells. In symbiotic hyphae the microtubule tracks and spindles of dividing nuclei were clearly distinguished in the mantle hyphae in the tip region of the short roots. In the Hartig net hyphae microtubule tracks changed to a less clear, reticulate structure. Actin was visualized as long filaments in vascular tissue cells and as small microfilament bundles in mantle hyphae. Short microtubules and actin dots were detected in cytoplasm‐containing hyphae on the strand surface. The possible role of the cytoskeletal elements in the maintenance of the ectomycorrhizal association is discussed.
Wound‐healing in Vaucheria longicaulis Hoppaugh var. macounii Blum.
Authors: TORNBOM LAURIE , OLIVEIRA LUSI 
Published: April 2006

SUMMARYDifferential interference contrast microscopy of the cytoplasm of Vaucheria longicaulis Hoppaugh var. macounii Blum reveals the presence of cable‐like strands (tracks). The cytoplasmic tracks are orientated parallel to the length of the filament, and the organelles are closely associated and appear to move along them. Nuclei, mitochondria and Rhodamine B‐positive bodies (RBIs) interact with a single track. Chloroplasts are closely associated with several tracks, although preferential association with one of the tracks is clearly observed. In uncut filaments, the different classes of organelles move independently of one another and travel at different speeds. Chloroplasts, mitochondria, RBIs, and smaller inclusions (SSIs) exhibit a bulk pattern of motion characterized by brief reversals in their primary pattern of movement that do not affect their final direction of travel. Nuclei move independently of each other and do not reverse their direction of movement. In cut filaments, cytoplasmic track density and relationship to organelles in the wound region during stage 1 is similar to that in uncut filaments. The cytoplasmic tracks extend into the wound‐healing vesicle cytoplasm. Mitochondria and similarly‐sized organelles move rapidly (in bulk) toward the wound site and into the wound‐healing vesicle. In stage 2, an increase in cytoplasmic track density is observed in the wound region, and bulk movement of mitochondria and RBIs occurs toward the wound site. Nuclei also move in bulk, unidirectionally toward the wound. Organelle retraction from the wound is restricted to the chloroplasts.Both uncut and cut filaments were treated with the cytoskeleton depolymerizers Cytochalasin B and Oryzalin to determine the role(s) of microfilaments and microtubules respectively in organelle movement and the overall role of the cytoskeleton in the wound‐healing process. In uncut filaments, cytoplasmic streaming is severely reduced by both Cytochalasin B and Oryzalin, with the greatest reduction observed following cytochalasin B treatment. In cut filaments Cytochalasin B shows a greater effect on chloroplasts, mitochondria, and RBIs behaviour, while Oryzalin preferentially affects the nuclei. The results indicate that the bulk movement of chloroplasts, mitochondria and RBIs in uncut filaments may be microfilament‐based, and the movement of nuclei microtubule‐based.
The marine lichen Lichina confinis (O. F. Müll.) C. Ag.: ultrastructure and localization of nitrogenase, glutamine synthetase, phycoerythrin and ribulose 1, 5‐bisphosphate carboxylase/oxygenase in the cyanobiont
Authors: JANSON SVEN , RAI AMAR N. , BERGMAN BIRGITTA 
Published: April 2006

SUMMARYThallus ultrastructure and the localization of proteins involved in photosynthesis, N2 fixation and ammonia assimilation was studied in the Lichina confinis (O. F. Müll) C. Ag.‐Calothrix symbiosis. The lichen thallus showed profuse branching. Within this, the cyanobiont was located in the cortical zone. Haustoria were frequently observed in contact with vegetative cells of the cyanobiont but not with heterocysts. An extensive mucilage layer containing numerous vesicles occurred around cyanobiont cells. Immunolabelling showed nitrogenase to be exclusively located in heterocysts of the cyanobiont and the free‐living Calothrix sp. Glutamine synthetase (GS) levels in the cyanobiont were found to be drastically decreased compared to the levels in free‐living (cultured) Calothrix sp. Such a decrease was more prominent in mature parts of the thallus than in the apical region. Rubisco was mostly located in carboxysomes of the vegetative cells of the cyanobiont. There were relatively low levels of Rubisco in the cytoplasm of vegetative cells, while heterocysts showed negligible levels. In free‐living (cultured) Calothrix sp., phycoerythrin (PE) was found to be located along the thylakoid membranes both in vegetative cells and heterocysts. Cyanobiont cells showed a similar pattern but the levels were relatively lower.