bluuebunny/crossref_metadata_2025_split huggingface dataset:
ULTRASTRUCTURE AND PHENOLIC HISTOCHEMISTRY OF THE CYCAS REVOLUTA‐ANABAENA SYMBIOSIS
Authors: OBUKOWICZ M. , SCHALLER M. , KENNEDY G. S. 
Published: May 2006

SUMMARY Anabaena showed a seasonal difference in nitrogen storage when growing in Cycas revoluta coralloid roots. In winter Anabaena had numerous cyanophycin granules while in summer there were few cyanophycin granules and many degenerate algal cells. Cellular protrusions were present in the developing algal zone of coralloid roots which may facilitate metabolic exchange between the host and phycobiont. By ferric chloride ultrahistochemistry, phenolic deposits were found in the mucilaginous material of the algal zone. Phenolic deposits were also found in adjacent cells on the plasma membrane, endoplasmic reticulum, within plastids, and at the periphery of coralloid roots. The distribution of phenolic constituents could therefore provide a mechanism for excluding micro‐organisms and permitting only Anabaena to grow in cycad coralloid roots.
FACTORS CONTROLLING THE DISTRIBUTION OF TILIA CORDATA AT THE NORTHERN LIMITS OF ITS GEOGRAPHICAL RANGE III. NATURE AND CAUSES OF SEED STERILITY
Authors: PIGOTT C. D. , HUNTLEY JACQUELINE P. 
Published: May 2006

SUMMARYFailure of regeneration of Tilia cordata in north‐west England is associated with almost complete sterility of the seeds. Between 1964 and 1979 significant numbers of fertile seeds were recorded only after the exceptionally warm summer of 1976. In contrast, large or moderate crops of fertile seed were produced at sites in central and southern England in at least 8 of these years.Comparative studies of pollination, fertilization and seed development at sites in north‐west England, central England and northern France show relatively small differences in the proportions of flowers which are pollinated but significant differences in the rates of extension of pollen‐tubes. In samples collected in 1977 from north‐west England germinated pollen was present on most receptive stigmas but many pollen‐tubes extended only a short distance down the style and the few which reached the base appeared to be arrested in the ovary wall. In French samples pollen had germinated on all receptive stigmas and numerous pollen‐tubes had reached the ovary within 2 days of pollination.These differences cannot be attributed to variation in the incidence of self‐pollination, as at least some trees of T. cordata in northern populations are almost certainly self‐fertile. The differences are correlated with temperatures at the time when the samples were collected. When pollen‐tubes are growing in sucrose solutions, their rate of extension shows a large response to temperature over the same range (15 to 25°C). Analysis of records shows that temperatures in north‐west England at the time of flowering are frequently too low to permit fertilization.This is confirmed by studies of the development of ovules. Although a high proportion of ovules in T. cordata lack embryo sacs, normally at least one is functional in each ovary. In over 90% of fruit formed in north‐west England, embryos are contained in none of the 10 ovules. In less than 10% of fruit partly developed embryos are present, suggesting that temperatures are also too low in late summer to allow completion of their development.
THE ACID INVERTASES OF THE DEVELOPING THIRD LEAF OF OAT
Authors: GREENLAND A. J. , LEWIS D. H. 
Published: May 2006

SUMMARYChanges in activities of soluble and insoluble acid invertases and in concentrations of ethanol‐soluble carbohydrates were examined during development of the third leaf of oat. The leaves did not contain any alkaline invertases. High activity of soluble invertase, high concentrations of reducing sugar and low concentrations of sucrose occurred in the non‐emerged lamina, enclosed by the sheaths of older leaves. In the developing emerged region, activity of soluble invertase rapidly declined to a steady state in the mature leaf. In this tissue, the concentration of total soluble carbohydrate was initially low but increased as the leaf matured and sucrose was always the predominant sugar. The activity of insoluble acid invertase remained relatively constant throughout leaf development. When invertase activities and amounts of soluble carbohydrates were compared in apical and basal regions of the mature leaf after ligule emergence, higher levels of both soluble and insoluble invertase, and total soluble carbohydrates, occurred in the apical half of the leaf.
ANALYSIS OF TRYPTOPHAN AND ITS METABOLITES BY REVERSE‐PHASE HIGH‐PRESSURE LIQUID CHROMATOGRAPHY
Authors: TARR JOHN B. , ARDITTI JOSEPH 
Published: May 2006

SUMMARYRapid separation and determination of tryptophan, N‐formylkynurenine, kynurenine, 3‐hydroxykynurenine, 3‐hydroxyanthranilic acid, nicotinic acid, nicotinamide, trigonelline, kynurenic acid and xanthurenic acid from pea seedling using reverse‐phase high‐pressure liquid chromatography is described. Accuracy of the determinations was better than 5 % and less than 50 pmol of each metabolite could be measured reliably.
THE INFLUENCE OF SOIL AERATION ON THE EFFICIENCY OF VESICULAR‐ARBUSCULAR MYCORRHIZAE I.
Authors: SAIF S. R. 
Published: May 2006

SUMMARYOxygen concentrations in the soil atmosphere greatly influenced the growth and mineral uptake of Eupatorium odoratum inoculated with Glomus macrocarpus. Shoot and root dry weights and length of mycorrhizal plants increased with O2 concentration up to 16%. Mycorrhizal plants at 21% O2 or non‐aerated controls were smaller than those at 12 and 16% O2. Non‐mycorrhizal plants had lower shoot and root dry wts than mycorrhizal plants at all O2 levels except at 0%. Phosphorus concentration in mycorrhizal and non‐mycorrhizal plants differed significantly but did not increase with increasing O2. Mycorrhizal plants contained higher quantities of N, K, Ca and Mg than non‐mycorrhizal and showed positive response in nutrient uptake to increase in soil O2. Inoculation and increased soil O2 resulted in higher concentrations of K and Mg but not of N and Ca. The development of Glomus macrocarpus exhibited quantitative and qualitative response to different soil O2 levels.
THE STRUCTURE OF THE SPORES OF GIGASPORA MARGARITA
Authors: SWARD R. J. 
Published: May 2006

SUMMARYLight and electron microscopy have been used to study the emergence through the spore wall and subsequent growth and development of the germ‐tube of Gigaspora margarita. Spore‐wall penetration by the germ‐tube is unusual as two different mechanisms seem to be operating, one for the inner spore‐wall layers and another for the outer layer. As the germ‐tube develops a primary wall layer is formed, and this can be traced back to its origin as a layer continuous with the thickened region of the innermost spore‐wall layer. In the maturing germ‐tube a highly osmiophilic secondary wall is deposited and this may be the wall layer that persists when the fungus penetrates a host root and sets up a mycorrhizal association.In common with other fungi that have been studied, the ultrastructural organization found in G. margarita can be categorized into approximately three zones: the apical zone, the subapical zone and the zone of vacuolation. Other features of the cytoplasmic organization are also discussed including the possible significance of bacteria‐like organisms, membrane‐bound crystals, osmiophilic granules and glycogen particles. Features of the culture‐grown germ‐tubes are also compared with those of host‐associated stages of the fungus reported in the literature.
DOMAINS OF ATPASE IN PLASMA MEMBRANES AND TRANSPORT THROUGH INFECTED PLANT CELLS
Authors: SPENCER‐PHILLIPS P. T. N. , GAY J. L. 
Published: May 2006

SummaryThe sites of ATPase at pH 7·2 and β‐glycerophosphatase at pH 5·5 and 7·2 in the presence of Mg2+ have been determined by a lead precipitation technique and electron microscopy in leaves of Pisum sativum and Phaseolus vulgaris infected, respectively, with Erysiphe pisi and Uromyces appendiculatus.In the two plants, ATPase activity was similarly high in plasma membranes of epidermal, phloem transfer and companion cells and much lower in those of their mesophylls. The domain of the host plasma membrane invaginated around haustoria showed neither of these enzymic activities but infection did not otherwise alter their activities in either the rest of the plasma membranes of infected cells or the plasma membranes in uninfected cells. In Erysiphe pisi, the plasma membrane showed high activities with ATP and β‐glycerophosphate in haustoria but in other regions and in Uromyces appendiculatus, it lacked activity with both substrates. The sites of transition of the enzymic activities in all instances occurred at annular structures previously described in the haustorial necks.A mechanism of solute transport into haustoria is proposed and discussed in the light of the polarized distribution of ATPase activity in infected cells.
SEED YIELDS (QUANTITY AND QUALITY) OF FIELD‐GROWN SOYBEANS EXPOSED TO SIMULATED ACIDIC RAIN
Authors: EVANS LANCE S. , LEWIN KEITH F. , CONWAY CHRISTINE A. , PATTI MITCHELL J. 
Published: May 2006

SummaryExperiments were performed to determine changes in mass, protein content and carbohydrate content of seeds of soybean plants exposed to simulated acidic rain grown under standard agronomic practices and receiving ambient rainfall at Brookhaven National Laboratory during the summer of 1979. Plots were exposed three times per week to simulated rainfalls of pH 4·0, 3·1, 2·7 or 2·3 to provide inputs of 50, 397, 998 or 2506 μequiv. of hydrogen ions respectively, above ambient levels throughout the growing season. Control plots received no simulated rainfall treatments. The results indicate significant differences by both analysis of variance and two‐tailed t‐tests. These additional hydrogen ions decreased seed yields by 2·6, 6·5, 11·4 and 8·5%, respectively. A treatment‐response function was determined between the hydrogen ion concentration of the treatments and seed yield. This function, y= 21·06 – 1·01 log x, has a correlation coefficient of minus 090 and its slope is significantly different from zero. Decreased yields were attributed to a decrease in number of pods per plant since seed number per pod and mass per seed did not vary among the treatments. On a per plant basis, total seed protein decreased by 10 and 19% in plants exposed to simulated rainfalls of pH 4·0 and 3·1, respectively, compared with plants not exposed to simulated rainfalls. At these same treatment levels total non‐structural carbohydrates did not decrease significantly. The results show that additional increments of simulated acidic rain can decrease seed biomass and protein content of field‐grown soybeans.
THE POTENTIAL FOR EVOLUTION OF SALINITY TOLERANCE IN AGROSTIS STOLONIFERA L. AND AGROSTIS TENUIS SIBTH
Authors: WU LIN 
Published: May 2006

SummaryTwo Agrostis stolonifera L. populations, one from a sandy seashore and one from an adjacent area were found to differ in salinity tolerance. Agrostis tenuis Sibth., which grew in adjacent areas where the soil salinity was low, was not found on the shore. The potential for evolution of salinity tolerance in both A. stolonifera and A. tenuis was studied. Substantial variation in salt (NaCl) tolerance was found among natural populations in both species. Specific ion tests suggested that the lack of magnesium tolerance in A. tenuis limits the evolution of seashore ecotypes. The selection of individuals with full salinity tolerance from a non‐tolerant population in one stage of the life cycle demonstrates that the salinity tolerance in A. stolonifera could evolve rapidly.
NEW FOSSIL EVIDENCE FOR THE PAST CULTIVATION AND PROCESSING OF HEMP (CANNABIS SATIVA L.) IN EASTERN ENGLAND
Authors: BRADSHAW R. H. W. , COXON P. , GREIG J. R. A. , HALL A. R. 
Published: May 2006

SummaryFossil records of Cannabiaceae pollen and Cannabis achenes from Flandrian deposits at three sites in eastern England are presented as further evidence for the past cultivation of this crop. It is suggested that retting of hemp to extract fibre was carried out at each of the sites.
EFFECT OF WATERING REGIME ON YIELD, WATER USE AND LEAF CONDUCTANCE OF SEVEN FESTUCA SPECIES WITH CONTRASTING LEAF RIDGING
Authors: SILCOCK R. G. , WILSON D. 
Published: May 2006

SummarySeedlings of seven Festuca species with contrasting leaf surface morphology were grown in pots with three different watering regimes to simulate full irrigation, intermittent soil moisture stress or prolonged soil moisture stress.When harvested at a similar growth stage, plants subjected to the greatest stress had the least shoot dry matter. Differences between treatments were greatest in the fastest growing plants, e.g. F. arundinacea cv. S.170. At harvest, mean transpiration rate was lowest in plants from the least stressed treatment and in species with the flattest leaf surfaces e.g. F. drymeja and F. gigantea. Whether or not allowance was made for the effect of the convolutions of the leaf surfaces in increasing effective leaf surface area, the ranking of the species for transpiration rate per unit leaf area under well watered conditions was the same.Overall water use efficiency (WUE) was greatest in plants subjected to prolonged soil moisture stress (383 mg shoot dry matter per 100 g of water transpired) and least in those which were intermittently stressed (301 mg per 100 g). WUE was also greater for the flatter leaved species, the greatest being for F. gigantea (437 mg per 100 g) and least for F. scariosa (275 mg per 100 g). These variations in water use efficiency were not closely related to daily maximum stomatal conductance or to stomatal density of the leaves.WUE was not highly correlated with any of the other parameters measured. At best, 46 % of the variation was associated (negatively) with the final rate of transpiration which in turn was closely correlated (positively) with the degree of adaxial leaf surface ridging.
PHYSIOLOGICAL‐ENVIRONMENTAL INTERACTIONS IN LICHENS
Authors: TEGLER B. , KERSHAW K. A. 
Published: May 2006

SUMMARYThe seasonal changes in the ability of Cladonia rangiferina to tolerate heat stress are examined in late winter, early spring and in summer. The effects of heat stress are examined as changes in net photosynthetic and respiration rates following air‐dry storage of lichen replicates at two stress temperatures, 35 and 45 °C, for 21 days. In late winter the experimental replicates show reduced net photosynthetic rates after 7 days stress treatment at 35 °C. By mid‐summer this treatment has no deleterious effects and it is concluded that there is approximately a 10 °C increase in heat tolerance in Cladonia rangiferina between late winter and mid‐summer.
EXPERIMENTAL STUDIES ON THE DISTRIBUTION OF THE SEXES OF MERCURIALIS PERENNIS L.
Authors: WADE K. M. , ARMSTRONG R. A. , WOODELL S. R. J. 
Published: May 2006

SUMMARY(1) In a beechwood, male shoots of Mercurialis perennis were more frequent than female shoots in canopy openings, while females were more frequent at treebases than in canopy openings.(2) Flowering shoots were more frequent than non‐flowering shoots in openings.(3) The pH, moisture and organic content of the soil were similar at treebases and openings. The light climate was similar in both habitats in April but greater in the openings in August.(4) Removal of canopies of Pteridium aquilinum and Rubus fruticosus, above populations of M. perennis, resulted in a greater increase in the numbers of male shoots than of female shoots.(5) These results suggest that male and female plants differ in numbers, or growth, in different woodland microhabitats and that these differences are correlated with the above‐ground environment (e.g. light).
Experimental Studies on the Distribution of the Sexes of Mercurialis Perennis L.
Authors: WADE K. M. 
Published: May 2006

SUMMARY(1) Transplants of Mercurialis perennis were grown under three canopy types; beech, mixed woodland and no overhead canopy (open), and in three different combinations under each canopy type; flowering males and females, flowering and non‐flowering males and females, and flowering males and females with Holcus mollis.(2) The males grew more than the females under the open and beech canopies, while the females grew more under the mixed canopy. The growth of the sexes did not vary consistently between the three treatments.(3) The results may explain the observed predominance of male flowering shoots in canopy openings of a woodland, but do not explain the predominance of female shoots at the treebases.(4) Both sexes grew most with H. mollis under the canopy type where they grew most in monoculture. However, the results suggest that the differences between the growth of the sexes were increased by growing with H. mollis.(5) An estimate of the flowering to non‐flowering shoot ratio was obtained, which showed that the ratio did not vary significantly with canopy type, suggesting that the differences in the numbers of flowering shoots of each sex at treebases and canopy openings in a woodland are not attributable to differences in the flowering to non‐flowering shoot ratio.
RESPONSES OF LEAVES OF PHASEOLUS VULGARIS L. TO SIMULATED ACIDIC RAIN
Authors: EVANS LANCE S. , CURRY THÉRÈSE M. , LEWIN KEITH F. 
Published: May 2006

SUMMARYRelative rates of nutrient penetration, nutrient leaching, and cell permeability of first trifoliate leaves of Phaseolus vulgaris L. cv. Univ. of Idaho 111 were examined after exposure to simulated acidic rain. In buffer solutions 35SO42‐ penetrated leaves faster at pH 2·7 than at 5·7. In contrast, 86Rb+ pervaded fastest at pH 5·7, and 3H2O entered foliage at similar rates at all pH levels tested. When plants were exposed to simulated rains of various pH levels, calcium, nitrate and sulphate were preferentially leached from whole leaves by rainfalls of low pH, whereas potassium and chloride leached more at pH 5·7 and 3·4 compared with 2·7 and 2·9. Isotope tests indicated that cells within leaves were more permeable to 35SO42‐ and 3H2O and less permeable to 86Rb+ at pH 2·7 than at higher pH levels. These results suggest a wide diversity of leaf and cell permeability responses to various ions after exposure to acidic rain. In general, an increased rate of nutrient leaching at more acidic levels was correlated with a lower adaxial leaf resistance during leaf development.
OVULE DEVELOPMENT IN ORNITHOGALUM CAUDATUM (LILIACEAE) WITH A REVIEW OF SELECTED PAPERS ON ANGIOSPERM REPRODUCTION
Authors: TILTON VARIEN R. 
Published: May 2006

SUMMARYArchesporial cell differentiation begins when ovules are four or five cells long. One parietal cell separates the archespore and nucellar epidermis. The parietal cell divides once anticlinally and its daughter cells divide once or twice periclinally resulting in four or six parietal cells. Archespore cytoplasm contains numerous small vacuoles and numerous circular, rod‐shaped bodies which stain for protein. RN A content is high. Archesporial cells increase two‐ or threefold in size and produce a megaspore mother cell which is circular in cross‐section and elliptical in longisection. Vacuoles seem to shrink slightly during the archespore/megaspore mother cell transition. Meiosis produces four megaspores separated from each other and from the nucellus by walls which stain intensely with basic fuchsin but do not fluoresce with Aniline blue. The chalazalmost megaspore typically becomes the functional megaspore while the others degenerate. Carbohydrates accumulate in the functional megaspore during the meiotic/mitotic interphase, and by metaphase, organelles, including amyloplasts, are in a perinuclear arrangement.
NATURALLY OCCURRING AUXINS AND INHIBITORS AND THEIR ROLE IN FRUIT GROWTH OF AONLA (EMBLICA OFFICINALIS GAERTN.)
Authors: RAM SANT , RAO T. RAJA 
Published: May 2006

Three acidic (a1, a2 and a3) and two non‐acidic (a4 and a5) auxins were detected in the immature fruit of aonla (Emblica officinalis Gaertn.). Chromatographic studies coupled with bioassays led to the tentative identification of a2, a4 and a5 as IAA, IAAld and IAN, respectively. Two growth inhibitors (R1 and R2) were also detected in the fruit. These behaved like naringenin and abscisic acid, respectively, in paper and thin‐layer chromatography.The inhibitors R1 and R2 were present in low concentrations in dormant fruits and did not appear to be the cause of dormancy. The factor playing a major role in the dormancy mechanism of the fruit appears to be auxin. Concentration of auxin increased in the fruit with the onset of dormancy and decreased to a low level prior to dormancy break. Shoots grew while fruits were dormant and dormancy break in fruits occurred after cessation of shoot growth. Since rise and fall in the rate of shoot growth corresponded with the period of rise and fall in the auxin content of dormant fruits and since shoot‐tips and dormant fruits contained identical auxins, it is proposed that the auxins translocated from the shoot‐tip to the fruit cause dormancy of fruits by a mechanism similar to that operative in apical dominance.
LIGHT QUALITY AND STEM GROWTH IN IMPATIENS PARVIFLORA DC.
Authors: YOUNG J. E. 
Published: May 2006

SummaryInternode and hypocotyl elongation were measured in Impatiens parviflora DC. in light environments in which extra far‐red light was mixed with white light from fluorescent tubes during the photoperiod and at the end of the photoperiod. Night breaks of varying spectral composition were also given. The logarithmic rate constant of internode elongation was found to be linearly related to the estimated proportion of phytochrome existing as the far‐red absorbing form. Supplementary far‐red light at the end of the day caused no significant increase in the elongation rate whereas night break treatments significantly increased the rate of internode elongation. Hypocotyl elongation was not related to the estimated phytochrome photo‐equilibrium and appeared to be under the control of both blue and red light. The results are discussed in relation to the hypothesis that the control of stem elongation by phytochrome is an adaptation for detecting and avoiding shade.
MYCORRHIZAS OF THE LILIIFLORAE
Authors: CHILVERS M. T. , DAFT M. F. J. 
Published: May 2006

SummaryVesicular–arbuscular mycorrhizal (VAM) infections were examined in 30 cultivars of Narcissus L., Tulipa L. and Crocus L. over a period of 2 years. There was considerable diversity in the morphology of the VAM infections amongst, and variation of levels within, different genera. The possible causes of these variations, such as high levels of soluble phosphorus and host repression of the VAM endophytes, are discussed. Seven endophytes were identified from spore morphology. No apparent relationship existed between level of VAM and spore numbers in the field. Tulipa and Crocus roots were devoid of root‐hairs. Analysis of the incidence of root hairs in relation to VAM infection in Narcissus suggested that mycorrhizas were significantly less likely to bear root hairs.
ASSIMILATION OF NITROGEN IN ROOT NODULES OF ALDER (ALNUS GLUTINOSA)
Authors: BLOM JAN , ROELOFSEN WIM , AKKERMANS ANTOON D. L. 
Published: May 2006

SummaryCitrulline is shown to be the predominant free amino acid in alder root nodules, while serine also occurs in relatively large amounts. Citrulline and glutamic acid are prominent free amino acids in alder xylem tissue. The activities of N2‐ase, GS, GDH, and OCT in root nodule homogenates are reported. From the Km values of GDH for NH4+ (16mM) and glutamate (0·9 mM) and the concentrations in the nodule of NH4+ (1·5 HIM) and glutamate (0·5 mM) it is concluded that GDH in alder nodules is responsible for the deamination of glutamate. The important function of GDH in the nitrogen metabolism of alder nodules is confirmed by the much higher activity of this enzyme in homogenates of nodules as compared to that in homogenates of root‐tips and leaves.The vesicle clusters, which contain the N2‐ase activity, did not show activity of GS, GDH and OCT. The cytoplasm of the host cells was shown to possess the GS activity, while GDH and OCT probably are localized in the organelles of the host cells.