bluuebunny/crossref_metadata_2025_split huggingface dataset:
VEGETATION AND SOIL FACTORS ON A HEAVY METAL MINE SPOIL HEAP
Authors: THOMPSON JILL , PROCTOR J. 
Published: May 2006

SUMMARYThe vegetation of a small Scottish metal‐mine spoil heap was sampled by means of 70 0.25‐m2 quadrats and classified into three groups. The most common species were Agrostis capillaris and Festuca rubra which were important constituents of all three groups. Soil samples were collected from each quadrat and analysed for pH, loss‐on‐ignition, heavy metal and nutrient elements in the soil solution and for several physical properties. The mine spoil was physically and chemically heterogenous with many of the soil solution samples having potentially toxic concentrations of copper, lead and zinc. The vegetation data were ordinated: axis 1 of the ordination was significantly correlated (positively) with all three heavy metal concentrations, silt and sand, and (negatively) with loss‐on‐ignition and potassium concentration; axis 2 was significantly negatively correlated with pH and calcium, nitrate and phosphate concentrations. Consideration of this ordination and comparisons between soil parameters associated with each of the three vegetation groups and with non‐vegetated quadrats, suggest that lead and zinc may be the major determining factors of the spoil‐heap vegetation. Low nutrients (except phosphate) and in some cases adverse soil physical factors might be important also. The apparently small influence of copper is discussed. Above‐ground parts of five plant species were collected from the mine spoil and were shown often to have high heavy metal concentrations which differed between species. Finally we discuss some implications of interspecific differences in metal‐mine occurrence within the genera Agrostis and Festuca.
EFFECTS OF CYCLOHEXIMIDE AND CHLORAMPHENICOL ON CHLOROPLAST REPLICATION IN SYNCHRONOUSLY DIVIDING CULTURED CELLS OF EUGLENA GRACILIS
Authors: HASHIMOTO HARUKI , MURAKAMI SATORU 
Published: May 2006

SummaryChloroplast replication and division of Euglena gracilis Z cells cultured synchronoulsy under a diurnal light–dark regime (14:10h light: dark) proceeded in the dark period and were completely inhibited by 5 μg ml1 cycloheximide (CHI) added during the dark period. In the presence of 2 μg ml−1 CHI, chloroplast replication slowed but could be accomplished by the end of a prolonged 24 h dark period, while both the cell and nuclear division were completely inhibited. Chloroplast replication in the presence of 2 μg ml1 CHI was completely inhibited if the dark period was replaced by a light period. Chloramphenicol (CAP) (1 to 2 mg ml−1) slightly inhibited chloroplast replication while accumulation of chlorophyll and total cellular protein were considerably reduced. From the results presented it is concluded that chloroplast replication in synchronously cultured cells of Euglena gracilis is dependent on cytoplasmic protein synthesis that takes place during the dark period rather than chloroplastic protein synthesis, and that a putative protein(s) involved in chloroplast replication is inactivated by light.
DIFFERENTIAL STARCH DEPOSITION: A ‘MEMORY’ HYPOTHESIS FOR NOCTURNAL LEAF MOVEMENTS IN THE SUN‐TRACKING SPECIES LAVATERA CRETICA L.
Authors: FISHER F. J. F. , FISHER P. M. 
Published: May 2006

SummaryOblique illumination of the lamina of Lavatera cretica produces asymmetrical deposits of starch as a function of light‐shadow patterns owing to surface irregularities. Asymmetrical deposits, produced immediately after sunrise each day, are believed stored until shortly before the next sunrise. During daytime tracking, deposits are evenly symmetrical. Overnight conversion of these even deposits is believed to continue for most of the night. Shortly before sunrise, however, only residual asymmetrical deposits remain to be converted. Resulting solute asymmetries in the translocation stream are believed to trigger turgor gradients in the pulvinus, so producing anticipatory movements just before dawn. Pre‐dawn movements thus actually repeat those accompanying the previous post‐dawn oblique lighting. Changing solute gradients across the pulvinar phloem, originating from shifts in sunlight direction, are cited as the probable cause of normal tracking adjustments.
COMPARISON OF NUTRIENT SOLUTIONS FOR GROWTH OF PLANTS IN SAND CULTURE
Authors: SMITH G. S. , JOHNSTON C. M. , CORNFORTH I. S. 
Published: May 2006

SummaryA comparison of eight different nutrient solutions showed large differences in ability to support growth of maize, ryegrass and white clover in silica sand. Plants grown with the Ruakura solution, a solution especially designed for pasture species, consistently outyielded those grown with the other nutrient solutions. Insufficient iron was a major cause of poor growth with many of the solutions, particularly for maize. However, where deficiencies of iron were corrected, growth differences, although smaller, still persisted among the nutrient solutions. Results of tissue analysis and measurements of the solution surrounding the roots showed a considerable number of individual factors which were likely to be yield limiting.
EVIDENCE FOR THE ABSENCE OF CHROMOSOME DIFFERENTIATION IN POPULATIONS OF SILENE MARITIMA WITH. GROWING ON HEAVY‐METAL‐CONTAMINATED SITES
Authors: COBON ANDREA M. , MURRAY B. G. 
Published: May 2006

Summary Silene maritima, a species that grows on coastal shingle and heavy‐metal‐contaminated mine spoils, was investigated to see whether these populations show any chromosomal differentiation. Karyotype studies do not reveal any difference between populations from metal‐free and metal‐contaminated habitats. Similarly, studies on the meiotic behaviour and pollen fertility of F1 hybrids between plants from the two types of habitat show no indication of chromosome change accompanying the evolution of metal tolerance.
A FURTHER POLLEN ANALYTICAL STUDY OF THE BLACKLANE PEAT SECTION ON DARTMOOR, ENGLAND
Authors: Simmons I. G. , Rand J. I. , Crabtree K. 
Published: May 2006

SummaryThe Blacklane Brook profile, first published in 1964, has been re‐examined and given firm dating in the light of the archaeological and fossil tree‐line interest that the profile has generated. A much fuller record of the open vegetation of Flandrian I is presented, and many new pollen types for the site are indicated. The recession phase noted in 1964 is found in this profile also and is dated to begin ca. 7760 BP. It is thus placed well within the Mesolithic cultural period. The resolution of the pollen diagram and the difficulties of interpretation of upland sites do not make it possible to make firm statements about the location of the tree‐line at different periods.
LEAF STOMATAL DENSITY AND DIFFUSIVE CONDUCTANCE IN THREE AMPHISTOMATOUS HYBRID POPLAR CULTIVARS
Authors: REICH PETER B. 
Published: May 2006

SummaryStomatal density and diffusive conductance were characterized for both leaf surfaces in three amphistomatous hybrid cultivars of poplar. Consistent differences in stomatal density were observed between cultivars and between leaf surfaces within a cultivar. Mean stomatal density in the three cultivars ranged from 150 to 330 stomata mm−2 for abaxial leaf surfaces and from 75 to 100 stomata mm−2 for adaxial surfaces. The density of stomata on the abaxial versus adaxial surface was related to the spatial orientation of leaves with respect to the horizon and this stomatal ratio ranged from 1–4 to 4–0 in the three clones. Also, stomatal density was greater in leaves at higher rather than lower nodal positions.Differences in diffusive conductance between cultivars and leaf surfaces were observed on intact and detached leaves in the light and dark. Within each cultivar mean abaxial conductance (Kab) was greater than adaxial conductance (Kad). Mean conductances in the light for the three cultivars ranged from 0–22 to 0–62 cm s−1 for abaxial, and from 0–15 to 0–17 cm s−1 for adaxial surfaces, and in the dark they were between 0.06 and 0.26 cm s−1 for abaxial, and from 0–04 to 0–06 for adaxial surfaces. The differences in conductance between cultivars and between leaf surfaces were correlated with their respective stomatal densities. Stomatal response to light and to leaf excision also varied between cultivars and between the two leaf surfaces.
BISULPHITE‐INDUCED PIGMENT DAMAGE IN THE BLUE‐GREEN ALGA NOSTOC CALCICOLA BRÉB.
Authors: SINGH S. P. , SINGH R. P. 
Published: May 2006

SummaryDamage to photosynthetic pigments is a useful criterion for assessing damage to aquatic plants exposed to bisulphite. The bisulphite‐induced damage to Chi a, carotenes and phycobilins in cells of Nostoc calcicola was dependent on both concentration and pH. Carotenes seemed most resistant to bisulphite, while phycocyanin was severely damaged even at extremely low levels of bisulphite. Higher bisulphite levels could be tolerated when the pH was initially adjusted to pH 8.0. The short‐term experiments revealed a shifting of the Chi α peak from 430 to 410 nm. The possible mechanisms leading to bisulphite‐induced pigment damage are discussed.
COBALT AND NITROGEN FIXATION IN LUPINUS ANGUSTIFOLIUS L.
Authors: DILWORTH M. J. , BISSELING T. 
Published: May 2006

SummaryBacteroids from cobalt‐deficient root nodules of Lupinus angustifolius L. cv. Unicrop were isolated and assayed for products of the cobalamin‐dependent enzymes methionine synthetase, ribonucleotide reductase and methylmalonyl‐CoA mutase.Since bacteroids from lupin nodules did not show propionate‐dependent O2 uptake, it was not possible to assess whether in vivo action of methylmalonyl‐CoA mutase was affected, although it appears unlikely to be of major significance.Cobalt deficiency decreased the DNA content per bacteroid in crown nodules, but not in later‐formed lateral nodules. The percentage of amino‐acid nitrogen accounted for by methionine was also lowered in bacteroids from crown nodules but not lateral nodules.
FLUXES OF PHOSPHORUS IN LEAVES OF BARLEY INFECTED WITH BROWN RUST
Authors: AHMAD I. , FARRAR J. F. , WHITBREAD R. 
Published: May 2006

SummaryThe movement of 32P, fractionation of 32P and unlabelled phosphorus, and efflux of 32P from leaf discs, in control and brown‐rust infected first leaf blades of barley are described for the day of sporulation, 7 d after infection. It is shown that P retranslocation is greatly reduced by disease, that the concentration of P in the infected leaf blade increases greatly and that the increase is probably largely in the fungus, and partly in the form of polyphosphate. The P content of fungal spores is derived largely from P currently entering the leaf in the xylem. The data are used to derive P budgets for control and infected leaf‐blades, and the significance of P to the diseased state is discussed.
OBSERVATIONS ON DRECHSLERA LEAF SPOT ON LOLIUM PERENNE AFFECTED BY CADMIUM
Authors: SCHOLES J. D. , SHATTOCK R. C. 
Published: May 2006

SummaryChlorotic patches in a three year old ley of Lolium perenne L. were associated with high concentrations of cadmium, lead and zinc in the soil. L. perenne in these patches was severely affected by Drechslera leaf spot. When cadmium at 10 to 25 μg cm−3 was added to plants grown in solution culture, or in soil as simulated swards, levels of disease resulting from inoculation were up to 10 times greater than on plants grown in cadmium‐free solution or soil. Cadmium reduced the dry weight of roots and especially shoots in both inoculated and uninoculated plants and accumulated in root and shoot tissues. Cadmium uptake decreased the uptake of potassium.
THE RESPONSE OF BARLEY LEAF EPIDERMAL CELLS TO INFECTION BY SEPTORIA NODORUM
Authors: KEON J. P. R. , HARGREAVES J. A. 
Published: May 2006

SummaryThe inability of Septoria nodorum Berk, to penetrate barley leaves was associated with the development of papillae beneath penetration sites and a modification to the structure of the cell wall surrounding papillae. Penetration hyphae did not progress further than the outer cellulose layers of the wall.Reaction sites (papillae and modified cell walls) were isolated using cellulase. Modified cell walls were resistant to cellulase and did not react with zinc chlor‐iodide, indicating that the cellulose microfibrils were protected from both the enzyme and the stain. Material deposited in the interfibrillar spaces appeared to be responsible for this protection. Callose could not be detected in papillae; however, this may have also been due to encrusting substances which prevented callose reacting with aniline blue. The material deposited within papillae appeared to be similar to that deposited in cell walls. Lignin could not be detected in reaction sites. Intense staining with Coomassie brilliant blue R250 and periodic acid Schiff's reagent suggested that both proteins and carbohydrates were deposited in these structures. The possibility that these deposits were glycoproteins is discussed.
THE INFLUENCE OF LIGHT AND POTASSIUM NITRATE ON THE DORMANCY AND GERMINATION OF AVENAFATUA L. (WILDOAT) SEED AND ITS ECOLOGICAL SIGNIFICANCE
Authors: HILTON JANET R. 
Published: May 2006

SummaryIt has been suggested that applications of nitrogen‐containing fertilizers can stimulate the germination of dormant Avena fatua L. seed in the field and may be used to reduce numbers of seeds in the soil. However, it is not clear whether a subsequent cultivation imposing a light treatment on a proportion of the buried seeds is also necessary. To study this question potassium nitrate (KNO3) was applied to dormant seed of A. fatua in darkness and in light under controlled laboratory conditions. Potassium nitrate had very little effect on germination in darkness but concentrations of 2 × 10−4, 2 × 10−3 and 2 × 10−2 M stimulated germination in the light. The degree of stimulation by light was related to the proportion of phytochrome that was maintained as Pfr, the physiologically active form. In the presence of 2 × 10−1 M KNO3 no germination occurred either in light or in darkness.
ANION ACCUMULATION BY LICHENS
Authors: NIEBOER E. , PADOVAN D. , LAVOIE P. , RICHARDSON D. H. S. 
Published: May 2006

SummaryPhosphate and sulphite competed effectively with arsenate when samples of Umbilicaria muhlen‐bergii (Ach.) Tuck, were incubated in arsenate solutions in the presence of increasing concentrations of the second anion. Equimolar amounts of phosphate had no effect on arsenate uptake while an 100‐fold excess of the former caused almost complete cessation of arsenate uptake. By contrast, sulphate enhanced arsenate uptake by lichen samples while acetate had no effect.In experiments on phosphate‐arsenate competition it was possible, by regarding the latter as an inhibitor, to evaluate the kinetics of phosphate uptake in If. muhlenbergii. The Km of 660 μM and the Vmax. of 0.059 μmol min−1 indicated that the lichen took up some ten times more arsenate than phosphate per unit time. Studies of photosynthetic fixation of 14C revealed that a reduction in photosynthesis was related to the amount of arsenate accumulated. Conditions which enhanced arsenate uptake (e.g. stimulation by sulphate) resulted in greater photosynthetic inhibition, while those that reduced uptake (e.g. inhibition by phosphate) had an ameliorating effect. The ecological implications of these results are discussed.
FURTHER ANALYSIS OF THE IN VITRO PHYTOCHROME MEDIATION OF THE AMOUNT OF GIBBERELLIN‐LIKE SUBSTANCES IN ETIOPLAST‐ENRICHED SUSPENSIONS ISOLATED FROM HORDEUM VULGARE L. LEAVES
Authors: HILTON JANET R. 
Published: May 2006

SummaryGibberellin‐like substances were extracted from light‐treated etioplasts to test the hypothesis that phytochrome controls their efflux. Results obtained using sucrose density centrifugation showed that phytochrome mediates a change in the extractability of gibberellins and does not mediate changes in the permeability of the etioplast envelope membrane with respect to gibberellins, as previously proposed.
EXAMINATION OF THE CUTICULAR SURFACES OF FRESH DELICATE LEAVES AND PETALS WITH A SCANNING ELECTRON MICROSCOPE: A CONTROL FOR ARTEFACTS
Authors: EVELING D. W. 
Published: May 2006

SummaryThe cuticle surfaces of fresh, uncoated petals of Nicotiana alata Link & Otto and leave of Phaseolus coccineus L., Coleus blumei Benth. and Dactylis glomerata L. were examined in a canning electron microscope using a range of accelerating voltages, beam currents and recording scan times. The best micrographs of undamaged and unwrinkled cuticles, taken at magnifications ranging from 500 to 5000. were‐obtained using an accelerating voltage of 10kV, a low beam current and a recording scan time of 40 s. Fixation of the cuticles with osmium tetroxide vapour neither reduced charging nor improved preservation.The examination of the fresh uncoated cuticles proved an acceptable check or control for other methods used to prepare the auricles for scanning elecrron microscopy.
A MATHEMATICAL DESCRIPTION OF THE EFFECT OF RESATURATION ON NET PHOTOSYNTHESIS IN THE LICHEN, PARMELIA PRAESIGNIS NYL.
Authors: LINK S. O. , NASH T. H. 
Published: May 2006

SummaryResaturation respiration occurs in Parmelia praesignis Nyl., although it is not strongly developed as in other lichens. Less than 2 h was required for full recovery of photosynthetic ability after having been dry for at least 5 weeks. After three daily, 4 h soaking periods the time for recovery was reduced to 11 min. The resaturation phenomenon is mathematically described for the first time as a negative exponential from which parameters can be derived for maximal net photosynthetic rate, maximal velocity and the velocity at the half‐time for recovery. Net photosynthetic rate was independent of the period of drought. The velocity at the half‐time for recovery increased by 81% after one soaking period and by 990% after two.
CRASSULACEAN ACID METABOLISM IN YOUNG ORCHID LEAVES
Authors: GOH C. J. , WARA‐ASWAPATI O. , AVADHANI P. N. 
Published: May 2006

SummaryAcidity fluctuations typical of Crassulacean acid metabolism (CAM) were observed in both young and mature leaves of a succulent orchid hybrid Arachnis Maggie Oei. The maximum level of acidity in young leaves was only half the peak value in the mature leaves. The stomatal rhythm and CO2 gaseous exchange of mature leaves exhibited CAM characteristics, whereas young leaves showed typical non‐CAM behaviour with low stomatal resistance and a net CO2 uptake during the day, high resistance and a net CO2 output during the night. The stomatal movement of both young and mature leaves was regulated by the internal CO2 concentration of sub‐stomatal chamber.
SUCROSE ACCUMULATION AND THE INITIATION OF FRUCTAN BIOSYNTHESIS IN LOLIUM TEMULENTUM L.
Authors: POLLOCK C. J. 
Published: May 2006

SummaryPlants of Lolium temulentum L. grown at 20 °C were transferred to 5 °C at the beginning of the light period. Sucrose accumulation was much more marked at low temperatures, with increases in rate detectable about 1 h following transfer. Exposure to low temperature over 7 d resulted in appearance of fructan, initially as oligosaccharides, and eventually as polymers of higher molecular weight. Sucrose accumulation was most marked in the blades of mature leaves, whereas the accumulation of fructan was maximal in the meristernatic regions of developing leaves. Chilling also led to a rise in activity of sucrose: sucrose fructosyltransferase, the first enzyme specifically involved in the biosynthesis of fructans. This activity was also higher in leaf meristems than in other regions of the plant.
SODIUM TRANSPORT INENTEROMORPHA INTESTINALIS(L.) LINK
Authors: RITCHIE R. J. , LARKUM A. W. D. 
Published: May 2006

SummarySodium transport was studied in the marine euryhaline alga,Enteromorpha intestinalisin seawater (465 mM Na+and in low salinity medium [Artificial Cape Banks Spring Water (ACBSW), 25.5 mM Cr, 20.4 mM Na+, 0.5 mM K+]. The intracellular Na+concentration ([Na+1]) ofE. intestinaliswas so low that it was difficult to detect using chemical and22Na+methods. Consequently, intracellular Na+fluxes were also difficult to measure. Most of the Na+of theEnteromorphatissue was bound to the fixed negative charges of the cell wall and this binding has, in previous studies, led to great overestimates of the intracellular Na+of this plant‐Data of22Na+labelling gave lower estimates of the Na+1] than a rinsing technique using isotonic Ca(NO3)2. The overall mean [Na+1] of seawater plants was only 5.5 ± 1.4 mM, with a value of 0.623 ± 0.163 mM Na+in ACBSW plants. With one exception, all the seawater22Na+experiments indicated a single intracellular exchange phase, i.e. a separate vacuolar phase could not be detected. The data on plants grown at low salinity could be interpreted as having either a single intracellular phase or two intracellular phases because of the problem of cell wall Na+exchange. No significant difference was found in total22Na+uptake or exchange fluxes in the light and dark in seawater‐grown plants but there may have been a light effect on low salinity plants. The Na+flux inEnteromorphaplants in seawater was about 3 nmol m−2s−1and in low salinity plants was about 0.2 nmol m−2s−1.Sodium inEnteromorphais far from electrochemical equilibrium (more than –100 mV) in plants in both seawater and ACBSW medium so that Na+is actively excluded from the cells. The plasmalemma has a very low Na+permeability (seawater, 3 pm s−1; ACBSW plants, either 3 or 100 pm s−1depending on which compartmentation model is accepted).
EFFECT OF EDTA ON ENDOGENOUS MANGANESE DURING INDOLEACETIC ACID‐INDUCED GROWTH OF A VENA COLEOPTILE SEGMENTS
Authors: KRISHNA T. MOHAN , BHARTI SUDHAKAR 
Published: May 2006

SummaryThe effect of ethylenediamine tetracetic acid (EDTA) on endogenous Mn2+ was studied by electron spin resonance (ESR) spectroscopy during indoleacetic acid (IAA)‐induced growth of Avena coleoptile segments. An enhancement in the concentration of endogenous Mn2+ was recorded in coleoptile segments treated with low concentrations (1 × 10−6 M) of EDTA or ethyleneglycol‐bis‐(β‐aminoethylether) N, N″‐tetracetic acid (EGTA ‐ 1 × 10−6 to 1 × 10−5 M), while at higher concentrations both EDTA and EGTA appeared to chelate Mn2+. An intermediate concentration of EDTA (5 × 10−5 M) interacted with IAA in enhancing the growth, while both lower (1 × 10−6M) and higher (5 × 10−6M) concentrations inhibited IAA‐induced growth. Inhibition of IAA‐induced growth at higher concentrations of EDTA was reversed by exogenous Mn2+. Concentration of endogenous Mn2+ declined further when IAA was present along with different concentrations of EDTA, except in coleoptile segments treated with 5 × 10−4 M EDTA. The data suggest that endogenous Mn2+ is essential for IAA‐induced growth and that a precise balance of free to bound/complexed Mn2+ may be involved in IAA action.
OBSERVATIONS ON FREE‐LIVING TREBOUXIA DE PUYMALYAND PSEUDOTREBOUXIA ARCHIBALD, AND EVIDENCE THAT BOTH SYMBIONTS FROM XANTHORIA PARIETINA (L.) TH. FR. CAN BE FOUND FREE‐LIVING IN NATURE
Authors: BUBRICK P. , GALUN MARGALITH , FRENSDORFF A. 
Published: May 2006

SummaryThe presence of free‐living Trebouxia and/or Pseudotrebouxia is documented. Several free‐living phycobionts were brought into culture and compared to the cultured Xanthoria parietina phycobiont. With the aid of both morphological and immunological criteria, we provide evidence that both the mycobiont and phycobiont of X. parietina can be found free‐living in nature. The potential for resynthesis between bionts under natural conditions is discussed.