bluuebunny/crossref_metadata_2025_split huggingface dataset:
Immobilization of pectin, xyloglucan and other soluble plant polysaccharides on blotting membranes
Authors: JEFFREE CHRISTOPHER E. 
Published: April 2006

SUMMARYSoluble polysaccharides, of natural and synthetic origins, are immobilized by nylon, nitrocellulose, and polyvinylidene difluoride blotting membranes. Retention of an acid and a neutral polysaccharide, measured using radioactive pectin and xyloglucan‐rich hemicellulose, exceeded 90% on some blotting membranes eluted in aqueous media. The two polysaccharides displayed different binding characteristics.Several polyanionic uronic acid polysaccharides, bound strongly to nylon 66 (Hybond N, Amersham) and to positively charge‐modified or cationic nylon blotting membranes (Hybond N +, Amersham), but much less strongly to paper, nitrocellulose or polyvinylidene difluoride. Fragments of pectin, including Rhamnogalacturonan I and Rhamnogalacturonan II, and galacturonic acid oligosaccharides as small as the dimer also bind to nylon membranes, and can be detected using cationic dyes or by means of their radioactivity. Xyloglucan‐rich hemicellulose in general binds more strongly than pectin to the same substrates. Of the substrates tested charge‐modified nylon gave best retention of pectin, and paper gave best retention of xyloglucan during washes in water and solutions of salts, acids and bases.The influence of pH and solutions of mono, di‐ and trivalent salts on the retention of some pectic polysaccharides by nylon was investigated. A large proportion, in excess of 70% of pectin applied to charge‐modified nylon, remained tightly bound at all salt concentrations up to 2 M.Soluble acid polysaccharides immobilized on blotting membranes could be detected by staining with cationic dyes, such as ruthenium red, alcian blue 8GX, and coriphosphine O, providing facile detection and a simple means of characterizing the cytochemical specificity of their staining reactions. Immobilized neutral polysaccharides, which do not react with cationic dyes, could usually be detected by the periodate‐Schiff reaction, or, if labelled with radionuclides, by autoradiography or scintillation counting.Soluble polysaccharides, like proteins and nucleic acids, may therefore be immobilized on blotting membranes for investigation with cytochemical, immunocytochemical, and other molecular probing and detection procedures. Quantitative binding data showed marked differences in the affinity of different polysaccharides for blotting substrates. Detailed characterization of the binding behaviour is therefore a prerequisite for optimization and rational application of polysaccharide blotting.
Growth and photosynthetic acclimation by Ranunculus aquatilis L. in response to inorganic carbon availability
Authors: MADSEN TOM VINDÆK 
Published: April 2006

SUMMARYRelative growth rates of Ranunculus aquatilis L. were measured in the laboratory at dissolved inorganic carbon (DIC) concentrations between 0.2 and 5.2 mM at air‐equilibrium CO2 (16 μM) and also at 0.55 mm DIC with elevated CO2 (350 μM). For plants grown at air‐equilibrium CO2, growth was limited by inorganic carbon below 1.6 mM DIC and the apparent half saturation constant was 0.5 mM. The growth rate at elevated CO2 was 50% higher than the carbon saturated rates obtained at high DIC concentrations and air‐equibrium CO2, where HCO3− is dominant. This difference is suggested to be caused by differences in uptake mechanisms for CO2 and HCO3− Uptake of CO2 is a diffusive process, whereas HCOa− use is an active process which involves uptake/transport systems in the cell membranes.The plants acclimated to the DIC regime for growth by reductions in carboxylation efficiency and bicarbonate affinity, but enhanced photosynthetic capacity at elevated DIC. Within the range of concentrations used, the acclimation to CO2 and HCO3− was quantitatively similar, except for the HCO3− uptake capacity which increased at high DIC and air‐equilibrium CO2 but declined at elevated CO2. Dark respiration was unaffected by inorganic carbon per se, but increased with growth rate. Maintenance respiration was constant among treatments. It is concluded that inorganic carbon, apart from being the primary substrate for photosynthesis, has secondary growth regulatory effects which affect the photosynthetic apparatus of the plants.
Relations between carbon and nitrogen during growth of Nannochloropsis oculata (Droop) Hibberd under continuous illumination
Authors: FLYNN K. J. , DAVIDSON K. , CUNNINGHAM A. 
Published: April 2006

SUMMARYGrowth of the marine eustigmatophyte Nannochloropsis oculata (Droop) Hibberd was Followed through two periods of batch growth from stationary phase until cessation of net C‐fixation. Growth continued for two generations after exhaustion of the N‐source (100μM NH4+), with an increase in the cell C/N mass ratio from 6 to 28. N‐deprived cells had a larger mean volume (130%) than N‐replete cells. Intracellular concentrations of carotenoids and Chla correlated with cell‐N until exhaustion of the N‐source, when Chla ml−1 of culture declined significantly. The contribution of intracellular amino‐N to cell‐N was less than 3% throughout exponential and stationary phases. The major intracellular amino acids were glutamate (Glu), glutamine (Gln) and alanine; concentrations of tyrosine (on a population basis) increased steadily during N‐deprivation. The intracellular concentrations of other amino acids showed fluctuations corresponding with changes in growth rate (e.g. arginine) or cell‐N (e.g. glycine). The intracellular ratio of Gln/Glu reached a peak of more than 26 within 3 h of inoculation of stationary phase cells into fresh medium, before falling to around 0.6 during exponential growth, and then remained below 0.1 after NH4− exhaustion. Of the extracellular amino acids, concentrations of alanine and serine remained relatively constant throughout, while those of glycine, glutamate and of total dissolved free amino acids increased during exponential and early post‐exponential phases, before levelling off at 1.4μM amino‐N. The behaviour of Nannochloropsis oculata is contrasted with the growth and physiology of Isochrysis galbana
Differences in photosynthetic performance between cyanobacterial and green algal components of lichen photosymbiodemes measured in the field
Authors: GREEN T. G. A. , BUDEL B. , HEBER U. , MEYER A. , ZELLNER H. , LANGE O. L. 
Published: April 2006

SUMMARYPhotosymbiodemes are lichens which contain a single mycobiont but have cyanobacteria and green algae as primary photobionts in different parts of the thallus. Members of a photosymbiodeme can be found as separate, free‐living lichen species. The photosynthesis of the components of two Pseudocyphellaria photosymbiodemes were studied in the natural forest environment in New Zealand. It was found that the green algal component had a large photosynthetic advantage when thallus water contents were low and the thalli were in equilibrium with atmospheric humidity. The cyanobacterial components were at an advantage when thallus water contents were very high. The environment in which photosymbiodemes are found, forest margins in high humidity areas, seems to provide the correct combination of thallus water contents so that neither component has a major advantage. The photosymbiodemes appear to be models, preserved by the special habitat and showing a possible early stage in the evolution before the definite separation of ecologically specialised green algal and cyanobacterial species.
Sites of entry of water into the symplast of maize roots
Authors: VARNEY G. T. , MCCULLY M. E. , CANNY M. J. 
Published: April 2006

SUMMARYFollowing our publication of a new method of calculating rates of water uptake by roots from measurements of the rate of accumulation on the roots of a marker solute, this paper describes the sites of accumulation of the solute, which indicate the sites where the water entered the symplast. Sulphorhodamine G (SR) was supplied in aeroponic mist culture to large maize plants with fully developed root systems. Root samples were collected after 4 to 8 h of transpiration in the dye‐mist from both axes and branches of the main roots, and from non‐transpiring (detopped) controls, frozen rapidly, freeze‐substituted, and embedded and sectioned by an anhydrous procedure that preserves the SR in place. Whole mounts and sections were examined by bright‐field, polarizing and epifluorescence microscopy. Major accumulations of SR were all at the outer surface of the roots, on Epidermal or root hair cell walls, or, in older roots where the epidermal cells were separating or dead, on the outer wall of the hypodermis. On some branch roots, though not on any main axes, the accumulations of SR were conspicuously aligned in the grooves over anticlinal cell walls of the epidermis. Non‐transpiring plants showed very slight accumulations. Diffusion of SR into the cell wall apoplast was limited by the suberized lamellae and Casparian bands of the hypodermis, except in some branch roots, where SR diffused throughout the cortical cell walls. In parts of roots where the epidermis and hypodermis had been damaged, SR diffused through cell walls of the cortex from the wound site. These patterns of accumulation show that water enters the symplast of roots at the outermost cell membranes of the root, whether they are epidermal or hypodermal cells. Water enters roots with fully developed hypodermises at high rates. The rote of the hypodermal suberization is to limit solute movement in the wall apoplast. A symplastic path for water throughout the cortex, endodermis and living cells of the stele is suggested.
A simple method for locating the start of symplastic water flow (flumes) in leaves
Authors: O'DOWD N. A. , CANNY M. J. 
Published: April 2006

SUMMARYThe identification of sites in leaves where transpiration water crosses cell membranes and enters the symplast has previously been made using freeze‐substitution to locate concentrations of dye [e.g. sulphorhodamine (SR)] moving with the transpiration stream, and left outside the membranes where the water passes through. These concentrations were called sumps, and the sites of entry to the symplast were called flumes. A simple method of locating sumps, and therefore flumes, is described. Fresh leaves, fed SR solution through their cut petioles for pulse periods of 0.5 h or more, followed or not by a chase of water, were sectioned by hand under paraffin oil, and the sections mounted in the same fluid. Observation of the sections by simple bright‐field microscopy revealed sumps of SR at the same sites, and of the same crystalline nature as found in the freeze‐substituted preparations. The saving in preparation time is of the order of > 100‐fold, at the sacrifice of resolution (5–10 μm compared with 0.2 μm). A limited survey of grass, sedge and dicotyledon leaves by this method confirmed in all essentials the results found by freeze‐substitution, and in addition, revealed flumes at the fusoid cells on the flanks of the veins of bamboo leaves, and at the same position next to the water tissue of Cyperus leaves. The rate of accumulation of crystalline SR in the sumps inside tracheary elements suggests that the concentration of this non‐permeating solute in the xylem sap increased by about 1000‐fold in the finest veins during 1–2 h of transpiration in the dye solution.
Humidity and light affect the growth, development and nitrogenase activity of stem nodules of Sesbania rostrata Brem
Authors: PARSONS RICHARD , SPRENT JANET I. , RAVEN JOHN A. 
Published: April 2006

SUMMARYThe growth and nitrogenase activity of stem nodules of Sesbania rostrata Brem were strongly influenced by the humidity surrounding the nodule. Nodules developed under high humidity showed the fastest rates of growth and the highest specific nitrogenase activity (determined by acetylene reduction). Development of stem nodules in both the light and dark was similar and showed a similar lowering of growth and activity with decreasing humidity. Stem nodules developed in the dark were pale and unlike the dark green nodules that developed in the light, they did not have chloroplasts in the nodule cortex. Adventitious root development required darkness and relative humidities approaching 100%. In stem nodules that were grown at high humidity and subsequently exposed to lower humidities, there was only a small loss of nitrogenase activity, and high rates of acetylene reduction were maintained for 6 d after treatments were begun. The area of nodule attachment to the stem or root was measured in nodules of many sizes and found to be consistently greater in stem nodules. This may have implications for the comparative water balance of nodules on these two organs.
Specificity of the Rhizobium—legume symbiosis obtained after mutagenesis in pea (Pisum sativum L.)
Authors: SAGAN M. , MESSAGER A. , DUC G. 
Published: April 2006

SUMMARYWithin a set of 13 induced symbiotic pea (Pisum sativum L.) mutants, two distinct mutated genes sym25 and sym26, selected for ineffective nodulation have been counteracted in their effect by Rhizobium strains 254 and 94 respectively, thereby establishing an N2‐fixing symbiosis. This suggests that mutagenesis can be a helpful tool in creating specificity systems such as those described in centres of origin and diversification of legume species.
Concentrations of indole‐3‐acetic acid in plants of tolerant and susceptible varieties of Chinese cabbage infected with Plasmodiophora brassicae Woron.
Authors: LUDWIG‐MÜLLER JUTTA , BENDEL ULRIKE , THERMANN PETRA , RUPPEL MANFRED , EPSTEIN EPHRAIM , HILGENBERG WILLY 
Published: April 2006

SUMMARYA convenient method for infecting Brassica seedlings in liquid medium with the Phytopathogenic fungus Plasmodiophora brassicae was developed. The infection rates of two susceptible and two tolerant Chinese cabbage varieties with wild type P. brassicae were investigated. The content of free indole‐3‐acetic acid (IAA) was determined using combined gas chromatography‐mass spectrometry (GC‐MS) with [13C6]‐IAA as internal standard during the first period of infection with the fungus (5–14 d) and compared with the indole glucosinolate content of two Chinese cabbage varieties (one tolerant, one susceptible) in the same developmental stages, The results showed that the mean of the IAA content in the infected plants was approximately 66.5% higher than that of the non‐infected controls. In both the susceptible and tolerant varieties higher levels of IAA were found in the infected plants 10 d after the beginning of incubation. After 14 d of incubation IAA levels decreased in the susceptible, infected plants and increased in the tolerant, infected plants.
Apoplastic antioxidants as decisive elimination factors within the uptake process of nitrogen dioxide into leaf tissues
Authors: RAMGE P. , BADECK F.‐W. , PLÖCHL M. , KOHLMAIER G. H. 
Published: April 2006

SUMMARYUptake of NO2 via stomata and its elimination in the mesophyll are investigated by use of mathematical models. Systems of differential equations describe simultaneous diffusion and reaction of the chemical species taken into account. The common hypothesis, postulating the disproportionation reaction of NO2 being the predominant path for the transformation of NO2 into the cellular nitrate and nitrite pools, could be false because of its failure to reproduce the measured sorption characteristics. If however the reduction of the pro‐oxidative NO2 by apoplastic ascorbate is taken into account the calculated uptake rates and the effects of changes in immission concentration and vegetational characteristics fit well within corresponding experimental results. The onset of acute injury in case of a fall in apoplastic ascorbate concentration below a critical level is postulated.
Environmental influences on the development of spruce needle cuticles
Authors: CAPE J. N. , PERCY K. E. 
Published: April 2006

SUMMARYSeedlings of Norway [Picea abies (L.) Karst.], red (P. rubens Sarg.), black [P. mariana (Mill) B.S.P.] and white [P. glauca (Moench.) Voss] spruce were grown from bud break to bud set outdoors, in the greenhouse, and in controlled environment chambers. The outdoor and greenhouse treatments also included adjacent shaded (50%) seedlings. The effects of growth environment on needle epicuticular wax production and morphology, and on needle wettability were investigated. Red and black spruce exhibited free growth in addition to determinate growth, but only in the greenhouse. Although relative growth rate was significantly lower for seedlings grown outdoors, there were no differences in wax morphology between outdoor‐ and greenhouse‐grown seedlings, Wax deposits on controlled environment seedlings were significantly more crystalline. Wax tubes were crystallized in ‘tufts’. There were significant differences in wax amounts recovered between species and treatments. Wax amounts relative to needle dry weights decreased in the order greenhouse > outdoors > controlled environment. Shaded red and black spruce produced significantly more wax than unshaded. Needles from seedlings grown in controlled environment chambers had the largest needle/droplet contact angles. These data indicate that seedling growth environment affects needle epicuticular wax characteristics and wettability. Studies designed to investigate factors determined by needle surface phystcochemical characteristics should include a consideration of growth environment.
Growth analyses on in vitro, ex vitro and auxin‐rooted hypocotyl cuttings of Pinus contorta Dougl. ex Loud.
Authors: GRÖNROOS ROLAND , FLYGH GUNNAR , KÄHR MONIKA , VON ARNOLD SARA 
Published: April 2006

SUMMARYThree different types of rooted hypocotyl cuttings showed relative growth rates close to those recorded as maximal for seedlings of Pinus contorta Dougl. ex Loud. However, slight differences in growth rate were noted depending on how the cuttings had been rooted. (I) Cuttings rooted in vitro initially formed a large wound tissue at the base from which roots subsequently developed. (II) Cuttings rooted ex vitro formed roots without previous formation of a wound tissue at the root‐shoot connection. I and II produced plants with in average two roots per plant and the plants grew at similar relative growth rates (6.86 and 6.88 % per day respectively). (III) Auxin‐rooted cuttings also formed roots (21 per plant) without previous formation of a wound tissue and had a slightly higher growth rate (7.65 % d−1). The growth rate of auxin‐rooted cuttings was not significantly different from the 8.67 % d−1 obtained in seedlings. The conclusions drawn from these experiments were that; (1) rooted cuttings have the capacity to grow almost as fast as seedlings, (2) wound tissue produced prior to rooting or an extended period before the roots develop does not have a negative affect on the growth capacity of the cuttings, (3) the number of roots per cutting did not affect growth rate.
Effects of cadmium on non‐mycorrhizal and mycorrhizal Norway spruce seedlings [Picea abies (L.) Karst.] and its ectomycorrhizal fungus Laccaria laccata (Scop, ex Fr.) Bk. & Br.: Sulphate reduction, thiols and distribution of the heavy metal
Authors: GALLI ULRICH , MEIER MARTIN , BRUNOLD CHRISTIAN 
Published: April 2006

SUMMARYThe effect of cadmium on assimilatory sulphate reduction and thiol content was studied in non‐mycorrhizal and mycorrhizal Norway spruce seedlings (Picea abies) and its ectomycorrhtzal fungus Laccaria laccata. The distribution of cadmium was also investigated. Isotope dilution experiments indicated that the fungus reduced sulphate via adenosine 3′‐phosphate 5′‐phosphosulphate sulphotransferase, whereas Norway spruce seedlings assimilated sulphate via adenosine 5′‐phosphosulphate sulphotransferase in both roots and needles. In mycorrhizal roots only the plant sulphotransferase activity could be measured. Mycorrhizal and non‐mycorrhizal roots and the mycelium of Laccaria laccata contained increased activities of sulphotransferase and more acid‐soluble thiols when cultivated with cadmium. The increase in acid‐soluble thiols was due to phytochelatins in roots and to glutathione in Laccaria laccata, where neither phytochelatins nor metallothioneins could be detected. Even though the cadmium content of mycorrhizal roots was slightly higher than that of non‐mycorrhizal roots, concentrations of phytochelatin were only half as high as in non‐mycorrhizal roots. Cadmium content of needles of mycorrhizal plants was significantly lower than that of non‐mycorrhizal plants. Most of the cadmium in Laccaria laccata was associated with the cell walls and could be exchanged with Ni2+.
Contrasting effects of elevated CO2 on the root and shoot growth of four native herbs commonly found in chalk grassland
Authors: FERRIS RACHEL , TAYLOR GAIL 
Published: April 2006

SUMMARYThe aim of this study was to investigate the impact of ambient (345 μl l−1) and elevated (590 μl l−1) CO2on the root and shoot growth of four native chalk grassland herbs: Sanguisorba minor Scop, (salad burnet), Lotus carniculatus L. (birdsfoot trefoil), Anthyllis vulneraria L. (kidney vetch) and Plantago media L. (hoary plantain).Elevated CO2 had contrasting effects on both shoot and root growth of the four species studied. Both leaf expansion and production were stimulated by elevated CO2 for S. minor, L. corniculatus and P. media, whilst for A. vulneraria, only leaflet shape appeared to be altered by elevated CO2, with the production of broader leaflets, compared with those produced in ambient CO2. After 100 d shoot biomass was enhanced in elevated CO2 for S. minor and L. corniculatus, whilst there was no effect of elevated CO2 on shoot biomass for A. vulneraria or P. media. Contrasting effects of CO2 were also apparent for measurements of specific leaf area (SLA), which increased for L. corniculatus, decreased for A. vulneraria and remained unaltered for S. minor and P. media in elevated compared with ambient CO2.Elevated CO2 also had contrasting effects on both the growth and morphology of roots. The accumulation of root biomass was stimulated following exposure to elevated CO2 for S. minor and L. corniculatus whilst there was no effect on root biomass for A. vulneraria or P. media. Root length was measured on three occasions during the 100 d and revealed that exposure to elevated CO2 promoted root extension in S. minor, L. corniculatus and P. media, but not in A. vulneraria. Specific root length (SRL, length per unit dry weight) was increased in elevated CO2 for one species, P. media, whilst the root to shoot ratio of all four species remained unchanged by CO2.These results show that four native herbs differ in their response to CO2, suggesting that the structure of this plant community may be altered in the future.
Plasmolysis: new insights into an old process
Authors: OPARKA KARL J. 
Published: April 2006

SUMMARYEarly microscopists made detailed observations of the phenomenon of plasmolysis, many of which have passed into the historical record without comment. This review considers the significance of these observations in the light of recent cell‐biological studies which are addressing the complex relationships between the plasma membrane (PM) and the extracellular matrix, as well as the interrelationships of the PM, endomembrane system and cytoskeleton. Emphasis is placed on the relative roles of Hechtian strand formation and PM vesiculation as mechanisms allowing the conservation of PM during a plasmolysis/deplasmolysis cycle. The behaviour of plasmodesmata during plasmolysis is considered in relation to the ability of cells to resume intercellular transport following deplasmolysis. Finally, the behaviour of cells during freeze‐induced ptesmolysis is addressed.ContentsSummary571I.Introduction572II.The vagaries of plasmolysia573III.The behaviour of the plasma membrane (PM) during plastnolysis575IV.Plasmodesmata582V.Vesiculation of the PM584VI.Effects of plasmolysis on wall growth587VII.Injury arising from plasmolysis588VIII.Concluding remarks589Acknowledgements589References589