bluuebunny/crossref_metadata_2025 huggingface dataset:
EFFECTS OF PRETREATMENT WITH PHOSPHATE IN NATURAL POPULATIONS OF AGROSTIS CAPILLARIS L.
Authors: MCCAIN S. , DAVIES M. S.
Published: May 2006

Summary

Clones of six populations of Agrostis capillaris L., collected from contrasting soils, were grown for one year in sand culture supplied with either 1 or 40 mg P dm−3 in weekly applied solutions (low and high P‐pretreatments). The pretreatments resulted in considerable phenotypic variation, measured as the fresh weight and chemical composition of tillers. The tillers were subsequently rooted in nutrient solutions containing aluminium (05 to 30 mg Al dm−3). Tillers of most phenotypes established successfully in control (0.5 mg Al dm−1) solutions while increasing Al concentration increased the number of tillers which failed to initiate roots. Therefore, when the length of the longest root on each tiller was measured after 18 d, unrooted tillers were recorded as zero values.

Tillers of low P‐pretreated plants produced longer roots than those of high P‐pretreated plants in control (0.5 mg Al dm−3) solutions but their root extension was more inhibited by increasing concentration of Al than that of the high P‐tillers. However, neither phenomenon could be directly related to the initial concentration of P in the shoots of the individual clones nor to any other measure of initial phenotype.

The responses of the populations to Al were not related to the chemical composition of their native soils. The findings are discussed in relation to the common practice of using vegetative tillers, propagated in conditions of high nutrient supply, in comparative ecological experiments.
DISTRIBUTION OF LIGNIN DERIVATIVES IN PLANTS
Authors: LOGAN KAREN J. , THOMAS BARRY A.
Published: May 2006

Summary

Acetovanillone, p‐hydroxybenzaldehyde, syringic aldehyde and vanillin were prepared from a range of gymnosperm, angiosperm, pteridophyte and bryophyte lignins by alkaline oxidation. The major lignin oxidation product of gymnosperms is vanillin; that of angiosperms is syringic aldehyde. The latter is more widespread than previously thought. Its identification seems to be linked in most cases to the presence of fibres in the plant tissues analyzed. The differentiation of gymnosperm and angiosperm plant groups on these oxidation products is discussed. It is proposed that the lignin of fibre walls is the reason for these differences.
FLANDRIAN ENVIRONMENTAL HISTORY OF THE ISLE OF MULL, SCOTLAND.
Authors: WALKER M. J. C. , LOWE J. J.
Published: May 2006

Summary

Pollen–stratigraphic evidence is presented from three sites in Glen More on the Isle of Mull, Inner Hebrides, Scotland, which spans the time interval from the wastage of the Loch Lomond Advance glaciers to the virtual disappearance of woodland from the island in the Late Flandrian period. Radiocarbon dates suggest that the Isle of Mull was deglaciated by about 10000 B.P., and palynological evidence from the base of the profiles implies time‐transgressive deglacial retreat of the ice that occupied Glen More. Wastage of the last glaciers on the island was followed by the expansion of Empetrum heath and juniper scrub, the latter being widespread by about 9600 to 9500 B.p. At that time birch woodland may have been present in the lowlands and in sheltered localities along the coastal fringes, but the spread of Betula into the hills of central Mull appears to have occurred some 200 to 300 years later. Coryhis avellana became widely established around 8800 B.p. and was followed by mixed woodland genera including Quercus, Ulmus, Pinus and Alms. The relatively low representation of arboreal pollen in all three profiles suggests, however, that woodland was never widespread on Mull during the Flandrian due principally, it would seem, to exposure to strong westerly winds. The expansion of grassland and CaWuna‐dominated heaths during the Late Flandrian reflects a change to wetter climatic conditions, but may also be partly a consequence of anthropogenic activity, particularly in lowland areas.
REGULATION OF ABSCISIC ACID CONCENTRATION IN LEAVES OF FIELD‐GROWN PEARL MILLET (PENNISETUM AMERICANUM [L.] LEEKE): THE ROLE OF ABSCISIC ACID EXPORT *
Authors: HENSON I. E. , MAHALAKSHMI V. , ALAGARSWAMY G. , BIDINGER F. R.
Published: May 2006

Diurnal changes in the concentration of abscisic acid (ABA) which occur in leaves of droughted, field‐grown plants of pearl millet (Pennisetum americanum [L.] Leeke) are not always correlated with changes in bulk leaf water potential (Φ). A rapid decline in ABA content of the leaves following its rise to a peak level in mid‐morning, was observed in several time‐course studies despite continued water stress.

The possibility that the reduction in ABA in leaves was due to an elevated rate of its export was examined in two ways: (i) by measuring ABA concentrations in developing panicles (possible sinks for leaf‐produced ABA) and in leaves, and (ii) by comparing the amounts of ABA in ungirdled leaves and in leaves heat‐girdled at the base of the lamina to block export. ABA concentrations in panicles generally paralleled those in leaves, though the peak level of ABA in the morning in panicles occurred later than in the leaves in some samplings. Although girdling initially increased ABA concentration, it did not prevent a subsequent fall which generally paralleled the decline observed in untreated leaves. The decrease in ABA that occurred despite the block to export and despite continuing stress was, therefore, attributed to changes in the synthesis or metabolism of ABA within the leaf.

The probable rate of export of ABA from leaves, calculated from the changes in its concentration due to girdling, was highest at the time of most rapid ABA accumulation and declined thereafter. The percentage export of recently assimilated carbon declined similarly. However, the probable absolute rate of export of photosynthate, computed from stomatal conductance and [14C]‐export measurements, was not uniquely related to that of ABA.
AN ESTIMATE OF THE ‘COST’ OF NUTRIENT LEACHING FROM FOREST CANOPIES BY RAIN
Authors: AMTHOR JEFFREY S.
Published: May 2006

Inorganic and organic substances are leached from forest canopies by rain. Estimates have been made of the percentage of net carbon assimilation associated with providing energy for both uptake and assimilation of substances leached from the canopy by rain. While leaching of nutrients from the canopy is a very significant component of nutrient cycles in forest ecosystems, it appears from the present calculations that it is generally only a minor factor in the energy (C) cycle. Energy losses associated with increased leaching as a result of rain acidification will probably cause only small reductions in forest productivity, unless they are the result of specific nutrient deficiencies.
ADVENTITIOUS ROOT FORMATION IN RELATION TO THE UPTAKE AND DISTRIBUTION OF SUPPLIED AUXIN
Authors: JARVIS B. C. , SHAHEED A. I.
Published: May 2006

Triiodobenzoic acid (TIBA) or morphactin (chlorfluorenol), applied to the base of the epicotyl of mung bean cuttings, inhibit root formation in the hypocotyl. Such inhibition occurs even when cuttings are supplied with auxin at the same time. Both treatments reduce the accumulation of radioactivity in the hypocotyl when [14C]IAA is supplied to the primary leaves. Morphactin does not influence the uptake of [14C]IAA supplied basally to cuttings, nor does it have any apparent influence on the distribution of radioactivity within the cutting. However, the extent to which [14C]IAA moves from leaves to hypocotyl is influenced by the basal supply of auxin in which cuttings are placed. These observations are discussed in terms of the role of the leaves in auxin‐induced adventitious root formation.
THE POTENTIAL IMPORTANCE OF AN INCREASED ATMOSPHERIC NITROGEN SUPPLY TO THE GROWTH OF OMBROTROPHIC SPHAGNUM SPECIES
Authors: PRESS M. C. , WOODIN S. J. , LEE J. A.
Published: May 2006

Atmospheric nitrate deposition varies across Northern Britain, and has increased approximately fourfold since the last century in the Manchester Region. Ombrotrophic mires depend on an atmospheric supply of elements, and some components of nitrogen deposition at two mire sites in northern Britain were investigated. The sites differed in proximity to major pollution sources. Growth of Sphagnum cuspidatum Hoffm, in bog pools was less in the polluted site and this was associated with a marked increase in tissue nitrogen concentration. Field experiments in which S. cuspidatum plants from unpolluted sites were exposed solely to atmospheric deposition in artificial bog pools showed that much of this large increase in nitrogen concentration could have resulted from atmospheric deposition alone. Concentrations of nitrate and ammonium within the range observed in bulk deposition at the polluted site reduced the growth of S. cuspidatum in a laboratory experiment. The results are discussed in relation to a general increase in atmospheric nitrogen deposition, and its potential importance to plant growth.
MUTAGENESIS AND ISOLATION OF MORPHOLOGICAL MUTANTS IMPAIRED IN NITROGEN‐FIXING CAPACITY FROM A CYNAOBACTERIUM GLOEOTRICHIA GHOSEI
Authors: MISHRA A. K. , TIWARI D. N.
Published: May 2006

Ultraviolet (u.v.) irradiation and treatment with nitrosoguanidine (NTG) were used to produce mutants of the cyanobacterium Gloeotrichia ghosei. Three non‐nitrogen fixing (nif−) mutants, which were also altered in their morphological characteristics, were isolated. They were designated as fil1 het+, fil1 het++ and pol− her−. The first two mutants formed heterocysts and exhibited polarity while the third (i.e. pol− het−) had neither heterocysts nor polarity. The fil1 het+strain had a developmental pattern similar to that of the parent alga, but with longer filaments, while the fil1 het++ strain formed chains of intercalary heterocysts and the long filaments showed evidence of intercalary polarity. The isolation of these mutants demonstrates the feasibility of using Gloeotrichia to relate developmental morphology to nitrogen fixation and heterocyst differentiation in a filamentous cyanobacterium.
GREATER LEAF CONDUCTANCE OF WELL‐WATERED VA MYCORRHIZAL ROSE PLANTS IS NOT RELATED TO PHOSPHORUS NUTRITION*
Authors: AUGÉ ROBERT M. , SCHEKEL KURT A. , WAMPLE ROBERT L.
Published: May 2006

Plants of Rosa hybrida L. cv. ‘Samantha’, grown with high or low phosphorus (P) fertilization, were inoculated with Glomus intraradices Schenck & Smith, G. deserticola Trappe, Bloss & Menge, or left non‐mycorrhizal. All plants except the low‐P non‐mycorrhizal group had similar tissue dry weights, leaf and root surface areas, growth ratios, stomatal characteristics and P contents. The higher rate of P fertilization increased plant dry weight three‐fold and leaf area four‐fold in non‐mycorrhizal plants, but had no effect on growth characteristics of mycorrhizal plants except for a depression of colonization levels. Under well‐watered conditions (75–90% and 45–50% relative soil water content, θ), low‐P mycorrhizal plants displayed greater leaf conductance (g) than both high‐P mycorrhizal and non‐mycorrhizal plants. Leaf water potential (Ψ) was similar in colonized and uncolonized roses. Fungal species did not differ significantly in their influence on Ψ or g.
THE STRUCTURE AND FUNCTION OF THE VEGETATIVE MYCELIUM OF ECTOMYCORRHIZAL PLANTS
Authors: FINLAY R. D. , READ D. J.
Published: May 2006

Using perspex observation chambers, the uptake, translocation and distribution of 32P‐labelled phosphorus was studied in ectomycorrhizal mycelial networks of Suillus bovinus (Fr.) O. Kuntze interconnecting plants of Pinus contorta Dougl. ex Loud and Pinus sylvestris L. Label was fed either directly to the cut ends of individual mycelial strands, to plant roots, or to the unsterile peat in the vicinity of advancing mycelial fans. Where 32P was fed to individual strands or mycelial fans it was taken up and translocated through the mycelium, over distances exceeding 40 cm, to all host plants connected to the mycelial network. Ectomycorrhizal roots acted as major sinks for phosphate but the label did not move exclusively towards the plant and was distributed throughout the mycelial system. Calculated translocation rates and flux rates suggest that transport is primarily by symplastic flow rather than turgor driven bulk flow. The amount of label accumulated by each plant was significantly related both to the size of the plant shoot and to the number of mycorrhizal root tips but did not appear to be influenced by the transpiration rates of individual plants. Phosphorus supplied directly to plant roots did not move to other plants via the mycelial connections suggesting that movement of phosphorus between the fungus and host is unidirectional.
A RE‐ASSESSMENT OF THE FORM OF REPRODUCTION IN DANTHONIA SPICATA (L.) BEAUV.
Authors: PHILIPSON MELVA N.
Published: May 2006

Despite early reports of cleistogamy in Danthonia spicata (L.) Beauv., recent authors have based their work on the incorrect assumption that aerial panicles are entirely chasmogamous and that cleistogamy is confined to axillary spikelets (cleistogenes). Of the florets contained in 122 panicles, 48% were chasmogamous and 52% cleistogamous. Only one panicle was entirely chasmogamous, whereas 58 were entirely cleistogamous. Chasmogamy was most prevalent in the lower parts of the spikelets and in the lower spikelets of the panicles. In addition to self‐fertilizing cleistogamous florets, an unknown but small proportion of non‐opening florets was sufficiently aberrant in their megasporogenesis to suggest that apomixis occurred. The possibility of the presence of apomixis should be considered within a typical cleistogamous system.
LATE PLEISTOCENE ZELKOVA EXTINCTION IN CENTRAL ITALY
Authors: FOLLIERI MARIA , MAGRI DONATELLA , SADORI LAURA
Published: May 2006

The genus Zelkova contains species which are nowadays distributed in an extremely fragmentary, mainly Asiatic, area. The Island of Crete retains geographically the species nearest to Italy. Fossil leaves and pollen discovered in some sites of Central Italy furnish evidence of the distribution of these trees before and during the Last (Eemian) Interglacial and of their persistence during part of the Last (Wurmian) Glaciation. The evidence is seen in two pollen diagrams from boreholes at Castiglione and Fucino which have stratigraphic continuity; at the base of the series Zelkova reaches conspicuous peaks in a phase which can be correlated with the Eemian Interglacial. During the climatic fluctuations of the last glacial Zelkova disappears in steppe periods and spreads again in favourable times up to the time of extinction, which seems to occur in both series somewhat before the latest glacial acme.
POLARIZED DNA SYNTHESIS AND CELL DIVISION IN CELL CLUSTERS DURING SOMATIC EMBRYOGENESIS FROM SINGLE CARROT CELLS
Authors: NOMURA K. , KOMAMINE A.
Published: May 2006

Embryogenic cell clusters derived from single cells of carrot (Daucus carota L. cv. ‘Kurodagosun’) showed polarized cell division during the initial stages of embryogenesis. Morphological and biochemical polarity during early embryogenesis were examined. Using an experimental system in which single cells differentiate to form embryos at high frequency, [3H]thymidine incorporation into cells and cell clusters was followed during the initial stage of somatic embryogenesis using autoradiography. Polarized incorporation of [3H]thymidine was observed after cell clusters passed the four‐cell‐stage. This polarity was preserved under conditions inducing embryogenesis, but was cancelled under conditions inducing non‐embryogenic growth. This indicates that the polarity of activity of DNA synthesis may be correlated with the expression of totipotency in embryogenesis.
THE ROLE OF ABSCISIC ACID AND CALCIUM IN DETERMINING THE BEHAVIOUR OF ADAXIAL AND ABAXIAL STOMATA
Authors: DE SILVA D. L. R. , COX R. C. , HETHERINGTON A. M. , MANSFIELD T. A.
Published: May 2006

Experiments are described which attempted to clarify the reasons for differences in stomatal opening on adaxial and abaxial epidemics. Previous studies had suggested that endogenous auxin levels might be responsible. It was found that adaxial stomata were more sensitive than abaxial stomata to externally supplied abscisic acid (ABA). It is suggested that differing endogenous concentrations of calcium ions in the upper and lower epidermes may contribute to the observed differences in sensitivity to ABA. It is further suggested that studies of stomata on isolated epidermis may represent a useful model system for examining the role of cell or tissue sensitivity in determining the responses to ABA and other hormones.

Data are presented which lend support to the suggestion that calcium ions play an important part. Treatment with lanthanum ions, which block calcium channels in cell membranes, had little effect on abaxial stomata, but caused the apertures of adaxial stomata to increase considerably. The chelating agent EGTA eliminated the differential behaviour of adaxial and abaxial stomata, which clearly suggests that calcium ions have a dominant role.

Experiments in which EGTA and fusicoccin were presented separately and in combination indicated that their effects were independent and additive. It is suggested that they operate at different locations, or on different processes in the guard cells.
EVIDENCE ON THE PATHWAYS OF PHOSPHORUS TRANSFER BETWEEN VESICULAR – ARBUSCULAR MYCORRHIZAL PLANTS
Authors: NEWMAN E. I. , RITZ K.
Published: May 2006

Mycorrhizal hyphae can link one root to another, and it is possible that phosphorus passes from plant to plant by these links. We present evidence on whether this ‘direct transfer pathway’ is the major route between mycorrhizal plants, or whether most phosphorus passes from the roots of one plant to the soil before being taken up by the other plant's roots or its associated mycorrhizal hyphae (the ‘soil pool pathway’).

The time‐course of loss of 32P from Lolium perenne L. roots to solution was measured after 32P had been fed to leaves. Another experiment indicated that the amount of 32P lost to soil was not influenced by mycorrhizal infection. 32P was applied to soil in which Plantago lanceolata L., mycorrhizal or non‐mycorrhizal, was growing and the time‐course of uptake determined. Using these results, two alternative models, the ‘direct transfer model’ and the ‘soil pool model’, were used to predict the time‐course and amount of 32P transfer from L. perenne to P. lanceolata. The predictions were then compared with measured transfers between these two species presented here and in a previous paper. The soil pool model's predictions of both amount and time‐course of transfer gave the better fit to observation.

The evidence thus suggests that direct hyphal links between roots are not important in phosphorus transfer between these plants.
NITROGEN OXIDES PRODUCED DURING CO2 ENRICHMENT III. EFFECTS ON TOMATO AT DIFFERENT PHOTON FLUX DENSITIES*
Authors: MORTENSEN LEIV M.
Published: May 2006

Seedlings of Lycopersicon esculentum (tomato) were subjected to CO2‐enriched air (1000 μl 1−1) containing 1.5 μ l−1 nitrogen oxides (NOX) for 25 d at four photon flux densities (30, 95, 175 and 250 μmol m−2 s−1 PAR).

CO2 enrichment without NOx significantly increased the dry weights (47 to 93 %) at all light levels. Addition of NOx strongly reduced the mean dry weight at the lowest light level even below that of the unenriched control. At the two highest light levels, NOx reduced the dry weight, but much less than at the lowest level. NOX caused severe leaf injury at the lowest light level, but this effect disappeared with increased photon flux density.

A system was constructed for measurement of the net CO., exchange rate (CER) for single plants. Short‐term measurements showed significant reductions of CER when the NO concentration was increased from 0 to 9μl 1−1 at 550μmol m−2 s−1 but almost no effect at 140 to 200 μmol m−2 s−1. NO caused similar percentage reductions of CER at 335 and 1000 μl 1 CO2. The absorption of NO was not significantly affected by increasing the photon flux density from 150 to 550μmol m‐2 s−2.
A COMPARATIVE STUDY OF GEUM RIVALE L. AND G. URBANUM L. TO DETERMINE THOSE FACTORS CONTROLLING THEIR ALTITUDINAL DISTRIBUTION
Authors: GRAVES J. D. , TAYLOR K.
Published: May 2006

The comparative growth of Geum rivale L. and Geum urbanum L. was determined, both over a range of temperatures under controlled conditions and throughout the year in field plots at three altitudes in the northern Pennines. Although under controlled conditions, the total dry matter accumulated was similar in both species, the change of relative growth rate with time was much more pronounced in G. urbanum than in G, rivale, especially at lower temperatures. In the field situation, there were no consistent differences in the overall growth pattern of the two species. The effect of altitude on growth was most pronounced during autumn and winter but was minimal in the summer. Root growth was less temperature‐sensitive than shoot growth in both species and was enhanced during the autumn. It is concluded that climatic limitation of growth is not so severe as to be the sole factor determining the altitudinal distribution of the species pair.
STAMEN FILAMENT STRUCTURE IN THE ASTERACEAE: THE ANTHER COLLAR
Authors: MEIRI L. , DULBERGER R.
Published: May 2006

The anther collar, i.e. the distal part of the stamen filament, was studied in 56 species belonging to 11 tribes of Asteraceae. In all the species, the structure of the collar differed considerably from that of the remaining part of the filament. Cells of the abaxial collar epidermis are large and have lignified walls. The cells of the adaxial epidermis are smaller and their walls, similar to epidermal cell walls in the remaining part of the filament, arc devoid of lignin. Variation was noted in the shape and size of the collar and in the thickenings of the epidermal walls. Presence of lignin in the collar indicates that this part does not participate in contraction of the filaments in species with sensitive stamens. It is suggested that the differences in structure and shape between the abaxial and adaxial sides of the collar determine an outward orientation of the curvature in the more elastic lower portion of the filament. This curvature leads to the formation of openings through which an insect may insert its proboscis to probe for nectar.
CALEDONIAN SCOTS PINE: ORIGINS AND GENETIC STRUCTURE
Authors: KINLOCH BOHUN B. , WESTFALL R. D. , FORREST G. I.
Published: May 2006

Monoterpene and isozyme loci, used as markers to study the genetic structure of Scots pine (Pinus sylvestris L.) native to Scotland, showed that the endemic populations are not genetically impoverished, in spite of severe contraction in range and numbers as a result of both natural and anthropogenic causes. On the contrary, variability in the relict populations is almost the highest: of any plant species studied, with average heterozygosities of 0.33 for monoterpenes (rive loci) and 0.30 for isozymes (16 loci). The overwhelming proportion of this variability (> 95 %) was within populations, even though significant differences in gene frequencies of many individual loci existed among populations. Multiple‐locus comparison of gene frequencies among populations, resolved by canonical variate analysis, showed no coherent geographic pattern of differences from population to population or region to region, with one major exception: certain populations in northwestern Scotland (Wester Ross) were distinct from all others and each other. The pattern of variability of the biochemical markers was consistent with that of metrical and physiological traits reported in the literature. These traits, in turn, show relatively little genetic affinity between contemporary Scottish and continental European populations. The genetic evidence, together with the anomalous distribution of pine pollen in the British Isles during the Holocene, suggests that the Caledonian race of Scots pine originated endemically from more than one refugium after the last glaciation.
PLANTS AND PEAT CUTTINGS: HISTORICAL ECOLOGY OF A MUCH EXPLOITED PEATLAND ‐ THORNE WASTE, YORKSHIRE, UK
Authors: SMART P. J. , WHEELER B. D. , WILLIS A. J.
Published: May 2006

Although many lowland raised bogs have been much modified or completely destroyed by agricultural reclamation, peat cutting, unaccompanied by reclamation, is not necessarily so destructive, and abandoned workings may provide a range of habitats that can support some of the original wetland plant species. Thome Waste, a much exploited raised bog in Eastern England, has a varied and well‐documented management history and comparatively good botanical records. It thus provides an exemplary site to assess the effect of peat exploitation upon its flora.

The origin and development, and subsequent drainage, reclamation and peat extraction history of the site are described, and their impact upon the past and present flora is evaluated. Some ombrotrophic mire species have been lost from the site, but one section of peat cuttings (the Dutch canal system, abandoned about 1920) has revegetated and supports an important range of these plants. Fen species, which once occupied the marginal lagg, have been almost completely eliminated from their original sites (which have mostly been reclaimed) but many have become re‐established in various new habitats created within the peat‐cutting complex. This illustrates the potential of artificial modification of worked‐over peatland sites to sustain a range of wetland plants.
THE INFLUENCE OF ZINC ON THE CELL CYCLE IN THE ROOT MERISTEM OF A ZINC‐TOLERANT AND A NON‐TOLERANT CULTIVAR OF FESTUCA RUBRA L.
Authors: POWELL M. J. , DAVIES M. S. , FRANCIS D.
Published: May 2006

Summary

Seedlings of a zinc tolerant cultivar (Merlin) and a non‐tolerant cultivar (S59) of Festuca rubra L. were grown in aerated solution culture at various concentrations of zinc.

The elongation of the longest root was much more inhibited by increasing Zn concentration in S59 than in Merlin. The mitotic index in the root meristem was reduced to a greater extent by increasing Zn concentration in S59 than in Merlin, whilst the cell doubling time (estimated by colchicine arrest) was increased by Zn much more in S59 than in Merlin.

The kinetics of the cell cycle in the root meristem were determined by a pulse labelling experiment with low specific activity tritiated thymidine following a 4‐d exposure to three concentrations of Zn (0, 0.1 and 0.2 μg Zn cm−3). Treatment with 0.1 and 0.2 μg Zn cm−3increased the length of the cell cycle by 40 and 132 % respectively (compared with the zero Zn control treatment) in S59 but only by 6 and 16% respectively in Merlin. The increase in cell cycle length was due mainly to an increase in the duration of G1 in both cultivars; Zn had little effect on the duration of the other phases of the cell cycle.

The growth fraction (the proportion of cycling cells in the meristem) was progressively reduced by increasing Zn concentration in S59 but was increased at 0.1 μg Zn cm−3in Merlin and then reduced to the control level at the higher Zn concentration.
EFFECT OF BENOMYL ON LEAF PHOSPHORUS CONCENTRATION IN ALPINE GRASSLANDS: A TEST OF MYCORRHIZAL BENEFIT
Authors: FITTER A. H.
Published: May 2006

Summary

Phosphate and the fungicide, benomyl, were applied to two alpine grasslands in the Kananaskis Valley, Alberta, Canada, to test the hypothesis that a reduction in leaf phosphorus concentration should result from reduction in vesicular‐arbuscular mycorrhizal (VAM) infection if mycorrhizal hyphae are the main route of P uptake by roots.

Benomyl successfully reduced infection in the roots of several species. At one site the result was an increase and not a decrease in leaf N and P concentrations, which was directly proportional to the original infection level, implying a benefit to the plant from the reduction in infection. At the other site, opposite trends were observed before and after a severe drought episode, implying that infection was initially deleterious and later beneficial. These results are adduced as evidence to support a hypothesis that VAM infection is only beneficial to plants under particular environmental conditions or at specific times in the year or life‐cycle.
GROWTH ANALYSIS OF MYCORRHIZAL AND NONMYCORRHIZAL BLACK OAK (QUERCUS VELUTINALAM.) SEEDLINGS
Authors: DAUGHTRIDGE ANN TODD , PALLARDY STEPHEN G. , GARRETT H. GENE , SANDER IVAN L.
Published: May 2006

Summary

Inoculation of seedlings of black oak (Quercus velutinaLam.) withPisolithus tinctorius(Pers.) Coker and Couch andSuillus luteus(L. ex Fr.) S. F. Gray stimulated total growth and several individual growth components as indicated by classical growth analysis of a 19‐week experiment. Inoculation withPisolithuswas more effective in increasing growth than was inoculation withSuillus.Mycorrhizal seedlings exhibited generally higher leaf area ratios than did uninfected seedlings from the seventh week after planting. Unit leaf rates (Ē) and relative growth rates (R̄) were higher for two of five harvest intervals in mycorrhizal plants, with the greatest values ofĒandR̄observed in seedlings inoculated withPisolithus.The alteration of growth patterns associated with inoculation was observed from six to nine weeks before substantial infection was detected. In general, mycorrhizal infection was associated with a greater relative investment of dry weight in leaf area and in early stimulation ofĒandR̄, a situation that increased total growth greatly as a result of early gains in productive plant mass.
β‐3‐DIMETHYLSULPHONIOPROPIONATE, PROLINE AND QUATERNARY AMMONIUM COMPOUNDS IN SPARTINA ANGLICA IN RELATION TO SODIUM CHLORIDE, NITROGEN AND SULPHUR
Authors: Van DIGGELEN J. , ROZEMA J. , DICKSON D. M. J. , BROEKMAN R.
Published: May 2006

Summary

Spartina anglica Hubbard seedlings were grown in nutrient solutions containing various concentrations of sodium salts, as the chloride, sulphate and sulphide. Two levels of nitrate were supplied to plants growing on the sodium chloride and sodium sulphate series. At low sodium chloride concentrations, higher growth rates were found in plants grown on the high nitrate level. At higher salinities, growth was inhibited and the inhibition was similar for plants grown on either of the two nitrate levels. Shoot levels of β‐3‐dimethylsulphoniopropionate (DMSP) showed no significant increase with increasing sodium chloride concentrations, at both nitrate levels. This strongly indicates that DMSP does not act as a compatible solute in S. anglica, grown under salt stress. Contrary to DMSP, levels of proline and quaternary ammonium compounds (QAC's) increased significantly in response to sodium chloride, and were significantly higher in plants grown on the high nitrate concentration. The influence of nitrogen availability on the accumulation of N‐containing compatible solutes and growth is discussed. Growth rates of plants grown in increasing sodium sulphate concentrations were not inhibited. DMSP levels in plants did not increase with a sulphate increase in the medium. A significant inhibition of plant growth by sodium sulphide was found. Sulphate in the plant increased with increasing sulphide levels in the nutrient solution and an increase of DMSP was found at the highest sulphide level. A possible function of DMSP as storage for excess sulphur is discussed.
A NOTATION FOR THE GROWTH OF INFLORESCENCES
Authors: ROBINSON D. F.
Published: May 2006

Summary

A notation for the representation of the elementary steps of the growth of a flowering plant, particularly the inflorescence, in terms of the development of different types of axillary and apical bud is introduced and illustrated by several examples. The system allows of greater precision and easier extension than do the descriptive names.
ARE UNISEXUAL FLOWERS PRIMITIVE?
Authors: THOMPSON K.
Published: May 2006

Summary

Sporne's statistical evaluation of primitiveness in angiosperms has generated a good deal of controversy, mainly because his identification of unisexual flowers as primitive is at variance with most other interpretations of angiosperm evolution. The controversy can be resolved by taking account of the fact that (a) the bisexual and unisexual states are readily interchangeable and (b) there are good adaptive reasons for expecting unisexual flowers to be correlated with woodiness. Given that woodiness is Sporne's most important indicator of primitiveness, the apparent evaluation of unisexual flowers as primitive is seen to have an adaptive rather than phylogenetic basis.
LOCALIZATION OF NITRATE REDUCTION IN FERNS AND ITS RELATIONSHIP TO ENVIRONMENT AND PHYSIOLOGICAL CHARACTERISTICS
Authors: STEWART GEORGE R. , POPP MARIANNE , HOLZAPFEL INGEBORG , STEWART JANICE A. , DICKIE‐ESKEW ANN
Published: May 2006

Summary

The capacity for nitrate reduction was shown to be present in the roots and shoots of all fern species examined. In many species the root was the major site of nitrate reduction, irrespective of the availability of external nitrate. The capacity for root nitrate reduction was positively correlated with root glutamine synthetase activity. Some species exhibited multiple forms of glutamine synthetase in their shoots. The activity of chloroplastic glutamine synthetase appeared to be correlated with photorespiratory potential. Root nitrate assimilation was most pronounced in shade ferns.
AN INVESTIGATION INTO NITROGEN ASSIMILATION AND DISTRIBUTION IN FRUITING PLANTS OF BARLEY (HORDEUM VULGARE L. cv. CLIPPER) IN RESPONSE TO NITRATE, AMMONIUM AND MIXED NITRATE AND AMMONIUM NUTRITION
Authors: SOARES M. I. M. , LEWIS† O. A. M.
Published: May 2006

Summary

Barley plants (Hordeum vulgare L. cv. Clipper) were grown to maturity in pH‐controlled, aerated solution culture with 2 mM inorganic 14N supplied as nitrate alone, ammonium alone or 1:1 nitrate+ammonium. At the end of the eighth week of growth, when seed filling was well advanced, the 14N feeding solutions were replaced by 15N feeding solutions, and the plants were grown in these media for 6 and 12 h before harvesting. l5N analyses of the plant material show that even at this late developmental stage, barley plants are still accumulating and assimilating considerable quantities of nitrogen (N), although at a much slower rate than in younger plants. Much of this N is incorporated into leaf protein. Transport of newly assimilated N from vegetative to reproductive parts is rapid, 22% of the assimilated (organic) l5N being found in the seed of NO3−‐fed plants at harvest, 26 % in NH4+‐fed plants and 17 % in NH4+‐fed plants. Inorganic N sources are not translocated to the seed in significant quantities. NH4+ and NH4++ NO3 ‐ fed plants show a much more rapid incorporation of N into both vegetative and reproductive organs than do NO3−‐fed plants; seeds of NH4++ NO3−‐fed plants gained organic 15N at a rate of 86 μg h−1 per plant, NH4+‐fed plants at 55 μg h−1 per plant and NO3−‐fed plants at 21 μg h−1 per plant. The poor organic 15N accumulation observed in NO3−‐fed plants is ascribed to the slow absorption rate of NO3− ions relative to NH4+ ions and the low nitrate reducing potential of the vegetative organs of the plant at this stage of development.
AMINO ACID AND AMIDE METABOLISM IN THE HULLS AND SEEDS OF DEVELOPING FRUITS OF GARDEN PEA, PISUM SATIVUM L. IV. ALANINE
Authors: MURRAY D. R.
Published: May 2006

Summary

Pea plants (Pisum sativum L. cv. Melbourne Market), each with a single developing pod, were pulse‐fed [14C]alanine supplied through the cut stem. The stages of pod development chosen were from 14 to 21 d after full blossom when alanine is one of the principal nitrogenous solutes secreted by the seedcoats into the embryo sac. In addition, [14C]alanine was supplied to a detached 14 d old pod via the base of the cut peduncle. After 24 h, the peduncles, hulls, seed components, and where appropriate, parts of the subtending leaf, were separated and frozen for later analysis. The distribution of label in soluble metabolites was determined by paper chromatography and radioautography. Of the total label in metabolites secreted into the embryo sac, only about 4% remained associated with alanine (14 d stage); when [14C]alanine was fed via the stem, most of this label was in sucrose (60%) and glutamine (27%), but when [14C]alanine was fed via the peduncle, most of the label entering the embryo sac was in glutamine. The results confirm that most of the alanine secreted into the embryo sac is synthesized in the seedcoats de novo from other solutes, notably asparagine.
PROPERTIES AND IMMUNOCHEMICAL CHARACTERIZATION OF NADPH‐SPECIFIC GLUTAMATEDEHYDROGENASE FROM EUGLENA GRACILIS
Authors: JAVED QAMAR , MERRETT MICHAEL J.
Published: May 2006

Summary

The NADPH–glutamate dehydrogenase (GDH; EC 1.4.1.4) from glutamate–grown cells of Euglena gracilis Klebs strain z. Pringsheim was purified to homogeneity by the criterion of polyacrylamide gel electrophoresis. The holoenzyme was shown to have a relative molecular mass of 180000 and to be composed of four subunits with a relative molecular mass of 45000. The pH optimum for the animating reaction was 80. The Km values for NH4+, α‐oxoglutarate and NADPH were 0.4 mM, 1.4 mM and 0.18 mM, respectively.

Antibodies raised to the purified enzyme showed no immunological correspondence with glutamic dehydrogenases from nitrate–grown Stichococus bacillaris and Porphyridium cruentum or ammonium–grown Chlorella vulgaris on Ouchterlony double–diffusion gels or by immuno–precipitation of enzyme activity. It is concluded that antigenic sites on the tetrameric Euglena enzyme may not be available on other NADPH–GDHs if they are hexamers.
STRUCTURAL CHARACTERISTICS OF ECTENDOMYCORRHIZAS SYNTHESIZED BETWEEN ROOTS OF PINUS RESINOSA AND THE E‐STRAIN FUNGUS, WILCOXINA MIKOLAEVAR. MIKOLAE
Authors: PICHÉ Y. , ACKERLEY C. A. , PETERSON R. L.
Published: May 2006

Summary

Ectendomycorrhizas were synthesized between Pimis resinosa Ait. (red pine) and the E‐strain fungus, Wilcoxina mikolae var. mikolae (Yang and Wilcox) Yang & Korf in growth pouches. A rudimentary mantle consisting of a few hyphae embedded in a matrix was formed. Although a I Iartig net was formed, the predominant phase consisted of intracellular hyphae in cortical tells of lateral and main roots. Cortical cells in basal portions of lateral roots showed various degrees of senescence, and hyphae in these cells were highly vacuolated.
THE EFFECTS OF SIMULATED ACID RAIN ON GERMINATIVE CAPACITY, GROWTH AND MORPHOLOGY OF FOREST TREE SEEDLINGS
Authors: PERCY KEVIN
Published: May 2006

Summary

Acid rain‐induced direct injury to forest tree seedlings was investigated in specially designed controlled‐environment simulated‐rainfall chambers. Seed germinative capacity, seedling survival, seedling growth and morphological responses to simulated rains of pH 5.6, 4.6, 3.6 and 2.6 were examined during the first growth cycle in 11 commercially important north temperate tree species. Germinative capacity was weakly responsive to rain pH, while seedling survival was more sensitive. No evidence of macroscopic foliar injury was observed at rain pH > 2.6. 1 reatment with pH 4.6 rain was sufficient to induce statistically significant growth reductions and morphological changes in coniferous seedlings. Response varied with species, treatment pH and parameter measured. No consistent growth stimulations were observed. Initiation of Primary needles, axillary meristems and shoot apex height were most affected by simulated pH. Deciduous species were considerably more resistant than coniferous species. Treatment with ram of pH 2.6 was generally required to induce significant growth reductions in deciduous seedlings.
Looking Forward: Cross‐cutting Issues in the Collection and Use of Racial/Ethnic Data
Authors: Lurie Nicole , Fremont Allen
Published: May 2006

Availability of reliable and valid race/ethnicity data is essential for monitoring and improving quality of care for minority groups. We explore the limitations and challenges posed by existing means of data collection and discuss issues that need to be considered as the data are analyzed and used.
Third‐generation Blood Pumps With Mechanical Noncontact Magnetic Bearings
Authors: Hoshi Hideo , Shinshi Tadahiko , Takatani Setsuo
Published: May 2006

Abstract:  This article reviews third‐generation blood pumps, focusing on the magnetic‐levitation (maglev) system. The maglev system can be categorized into three types: (i) external motor‐driven system, (ii) direct‐drive motor‐driven system, and (iii) self‐bearing or bearingless motor system. In the external motor‐driven system, Terumo (Ann Arbor, MI, U.S.A.) DuraHeart is an example where the impeller is levitated in the axial or z‐direction. The disadvantage of this system is the mechanical wear in the mechanical bearings of the external motor. In the second system, the impeller is made into the rotor of the motor, and the magnetic flux, through the external stator, rotates the impeller, while the impeller levitation is maintained through another electromagnetic system. The Berlin Heart (Berlin, Germany) INCOR is the best example of this principle where one‐axis control combination with hydrodynamic force achieves high performance. In the third system, the stator core is shared by the levitation and drive coil to make it as if the bearing does not exist. Levitronix CentriMag (Zürich, Switzerland), which appeared recently, employs this concept to achieve stable and safe operation of the extracorporeal system that can last for a duration of 14 days. Experimental systems including HeartMate III (Thoratec, Woburn, MA, U.S.A.), HeartQuest (WorldHeart, Ottawa, ON, Canada), MagneVAD (Gold Medical Technologies, Valhalla, NY, U.S.A.), MiTiHeart (MiTi Heart, Albany, NY, U.S.A.), Ibaraki University’s Heart (Hitachi, Japan) and Tokyo Medical and Dental University/Tokyo Institute of Technology’s disposable and implantable maglev blood pumps are also reviewed. In reference to second‐generation blood pumps, such as the Jarvik 2000 (Jarvik Heart, New York, NY, U.S.A.), which is showing remarkable achievement, a question is raised whether a complicated system such as the maglev system is really needed. We should pay careful attention to future clinical outcomes of the ongoing clinical trials of the second‐generation devices before making any further remarks. What is best for patients is the best for everyone. We should not waste any efforts unless they are actually needed to improve the quality of life of heart‐failure patients.
Development of Lorentz Force‐Type Self‐bearing Motor for an Alternative Axial Flow Blood Pump Design
Authors: Lim Tau Meng , Zhang Dongsheng
Published: May 2006

Abstract:  A Lorentz force‐type self‐bearing motor was developed to provide delivery of both motoring torque and levitation force for an alternative axial flow blood pump design with an enclosed impeller. The axial flow pumps currently available introduce electromagnetic coupling from the motor’s stator to the impeller by means of permanent magnets (PMs) embedded in the tips of the pump’s blades. This design has distinct disadvantages, for example, pumping efficiency and electromagnetic coupling transmission are compromised by the constrained or poor geometry of the blades and limited pole width of the PMs, respectively. In this research, a Lorentz force‐type self‐bearing motor was developed. It is composed of (i) an eight‐pole PM hollow‐cylindrical rotor assembly supposedly to house and enclose the impeller of an axial flow blood pump, and (ii) a six‐pole stator with two sets of copper wire and different winding configurations to provide the motoring torque and levitating force for the rotor assembly. MATLAB’s xPC Target interface hardware was used as the rapid prototyping tool for the development of the controller for the self‐bearing motor. Experimental results on a free/simply supported rotor assembly validated the design feasibility and control algorithm effectiveness in providing both the motoring torque and levitation force for the rotor. When levitated, a maximum orbital displacement of 0.3 mm corresponding to 1050 rpm of the rotor was measured by two eddy current probes placed in the orthogonal direction. This design has the advantage of eliminating the trade‐off between motoring torques, levitating force, and pumping efficiency of previous studies. It also indicated the benefits of enclosed‐impeller design as having good dynamic response, linearity, and better reliability. The nonmechanical contact feature between rotating and stationary parts will further reduce hemolysis and thromboembolitic tendencies in a typical blood pump application.
Computational Fluid Dynamics and Digital Particle Image Velocimetry Study of the Flow Through an Optimized Micro‐axial Blood Pump
Authors: Triep Michael , Brücker Christoph , Schröder Wolfgang , Siess Thorsten
Published: May 2006

Abstract:  A detailed knowledge of the flow field in a blood pump is indispensable in order to increase the efficiency of the pump and to reduce the shear‐induced hemolysis. Thus, three different impeller designs were developed and tested by means of computational fluid dynamics (CFD) and digital particle image velocimetry (DPIV). The results show a good agreement of CFD and DPIV data. An optimization of the impeller could be achieved by following the concept of turbulent drag reduction for the axisymmetric center body.
Emotion‐Triggered Cardiac Asystole‐Inducing Neurocardiogenic Syncope
Authors: CATANZARO JOHN N. , MAKARYUS AMGAD N. , ROSMAN DAVID , JADONATH RAM
Published: May 2006

The pathophysiology of neurocardiogenic syncope (NCS) is multifactorial. Recurrent syncopal episodes can result in injury and can provoke substantial anxiety among patients. Although an abundance of descriptions of various forms of syncope have been reported in the literature, few articles to date address a documented case due to emotional stress or sound. This is a report of a 31‐year‐old woman who fainted after being startled by someone sneezing. Review of the episode on her event recorder revealed a transient cardiac asystole of 10 seconds. We discuss the incidence of NCS and the proposed mechanism by which this syncopal event occurred.
Genetic Analysis of Six STR Polymorphisms in a Southern Chinese Population
Authors: Wang Chu , Ye Qian Su , Tang Jian Pin
Published: May 2006

POPULATION: A total of 105 unrelated and healthy individuals from the Han ethnic group of Nanning city in south China.
Population Data on HLA‐DQA1, LDLR, GYPA, HBGG, D7S8, and GC PCR‐Based Loci in Serbia
Authors: Puzović Dragana , Dunjić Dušan , Popović Branka , Stojković Oliver , Novaković Ivana , Milašin Jelena
Published: May 2006

POPULATION:Caucasians (n=131).
Genetic Polymorphisms at Four STR Loci from the HLA Region in a Venezuelan Population
Authors: Fernández‐Mestre Mercedes , Alfonso‐Sánchez Miguel A. , Gendzekhadze Ketevan , Layrisse Zulay , Peña José A.
Published: May 2006

POPULATIONS: Whole blood samples from 74 unrelated healthy individuals were collected. The donors' sample included Venezuelan mestizos from various regions of the country, but mostly from the resident population of Caracas City. A Venezuelan mestizo is the offspring of a mating between a native Venezuelan and a person born in Europe, mainly in Spain.
Population Genetics of Two STR Loci D2S1346 and D2S1353 in a Han Population of Chinese
Authors: Sun Xiao Ming , Fang Yue Qin , Yun Li Bing , Bai Peng , Li Zhou Ru , Zhang Ji , Li Ying Bi , Wu Jin , Hou Yi Ping
Published: May 2006

POPULATION: Chinese.
Genetic Polymorphism for the PowerPlexTM 16 System from the Chinese Tujia Ethnic Minority Group
Authors: Wei Han , Zhao Qianzi , Li Shengbin
Published: May 2006

POPULATIONS: The population studied was the Tujia population, living in the Hunan Province, China. Their ancestors had lived in the region for at least three generations. As a Chinese minority group, the Tujia ethnic group, with a population of 8,028,133 (year of 2000), is mainly distributed in the Wuling mountain area in the three provinces of Hunan, Hubei, and Sichuan. The Tujia population have their own language, which belongs to the Tibetan–Myanmese Language Group of the Chinese–Tibetan Language Family, but the large majority have come to speak the Han and Miao languages, now that the Tujias have been largely assimilated.