bluuebunny/crossref_metadata_2025_split huggingface dataset:
Freeze Preservation of Cultured Plant Cells
Authors: NAG K. K. , STREET H. E. 
Published: April 2006

AbstractA slow rate of cooling (1–2°C/min) is essential for high survival during the freezing phace. Death of cells during this phase takes place at temperatures below the freezing point of the suspending media, predominantly in the temperature range 10°C to −50°C. In the absence of cryoprotectants survival drops to zero between −30°C and −40°C. Fast thawing (water bath at 37°C giving a rate of temperature rise of 120°C/min between −50°C and −10°C) yields the highest recovery of viable cells. An interaction between cooling rate and thawing rate was demonstrated; this served to emphasize the importance of fast thawing. Under the best conditions realized in these experiments the percentage survival of cells cooled to −196°C was for carrot 70–75%, for belladonna 30–40% and for sycamore 20–25%. Storage for long periods (up to 10 months) at −196°C did not lead to any decline in percentage survival. Carrot cultures which had been stored for 10 months at −196°C showed no change in cell morphology or growth potential in culture and retained embryogenic potential.
Effects of AMO‐1618 and B‐995 on Growth and Endogenous Gibberellin Content of Cupressus arizonica seedlings
Authors: KUO C. G. , PHARIS R. P. 
Published: April 2006

AbstractSoil drenches of 250, 500 or 1000 mg/l of the growth retardants AMO‐1618 or B‐995 effectively reduced dry matter production and stem elongation in young seedlings of Cupressus arizonica Greene. In seedlings treated with AMO‐1618, the acidic, ethyl acetate‐soluble gibberellin‐like substances (GAs), as detected. by bioassay, were reduced to almost undetectable levels. However, the endogenous GA content in seedlings treated with B‐995 were at least 11‐fold greater than in control seedlings and differed as well in chromatographic characteristics, being of a more polar nature than the endogenous GAs of control seedlings. It was concluded that while AMO‐1618 probably acts through interference with GA biosynthesis, B‐995 may act through the interconversion of GAs.
Effects of Activated Charcoal on Growth and Morphogenesis in Cell Cultures
Authors: FRIDBORG GUNNAR , ERIKSSON TAGE 
Published: April 2006

AbstractThe effects of activated charcoal on growth and morphogenesis in plate cultures of different plant cells have been studied. It was shown that medium containing charcoal induced embryogenesis in cultures of Daucus carota in which embryo formation could not be brought about by omitting auxin from the medium. Charcoal‐medium also induced abundant root formation in older cultures of Allium cepa, which normally did not produce roots. The growth of cultures of Glycine max and Haplopappus gracilis was totally inhibited by charcoal. It is thought that activated charcoal removes substances from the medium, one of which might be auxin.
Control of Light‐Induced Carotenoid Synthesis in Raphanus Seedlings by Phytochrome
Authors: LICHTENTHALER HARTMUT K. 
Published: April 2006

AbstractThe effect of short pulses of red and or far‐red light on the formation of individual carotenoids was tested in etiolated radish seedlings (Raphanus sativus L.). Red light induces an enhanced synthesis of β‐carotene, lutein. violaxanthin and neoxanthin, while the level of antheraxanthin is decreased. Far‐red light reverses the red light effects to the level of the far‐red light control. The data indicate that in radish seedlings active phytochrome Pfr initiates the light‐induced carotenoid synthesis, which is bound to thylakoid formation.
Acidification of the Medium Associated with Normal and Fusicoccin‐Induced Seed Germination
Authors: LADO PIERA , RASI‐CALDOGNO FRANCA , COLOMBO ROBERTA 
Published: April 2006

AbstractFusicoccin, a toxin stimulating cell enlargement and inducing proton extrusion in various plant tissues, has been shown to replace kinetin, gibberellic acid and red light in breaking seed dormancy. It also removes the inhibitory effect of abscisic acid.The present data also show that the stimulating effect of fucicoccin on embryo growth of decoated radish (Raphanus sativus L.) and maize (Zea mays) seeds and on the development of maize embryos is accompanied by an early, significant acidification of the medium. Acidification of the medium is also observed when fusicoccin reverses the abscisic acid‐induced inhibition of germination. These results support the hypothesis that the mode of action of fusicoccin in promoting germination involves, as in stimulation of cell enlargement, the activation at the cell membrane level of proton extrusion processes.The physiological significance of fusicoccin‐induced release of protons at the onset of germination is discussed in comparison with the results concerning the mechanism of action of fusicoccin on cell enlargement in other plant materials.
A System for Continuous Measurement of Photosynthetic Rate and Dark Respiration at Constant CO2‐Level
Authors: NILSEN STEIN , KRISTIANSEN ERNST , HALLDAL PER 
Published: April 2006

AbstractA system for maintaining a constant CO2‐level during photosynthesis and dark respiration in an assimilation chamber is described. The assimilation chamber has two loops for control of the CO2‐level. If the CO2‐concentration is increased over a preset value, CO2 is removed by passing the gas flow over a lime filter. If CO2 is consumed, concentrated CO2 is added to the system. The system is operated through the computer in the Phytotron and has been constructed mainly for studies of dusk and dawn effects on photosynthesis where a high degree of control of the CO2‐level in the system is of the utmost importance.
Preconditioning of Tobacco and Bean Leaves to Heat Shock by High Temperature or NaCl
Authors: BENZIONI ALIZA , ITAI CHANNAN 
Published: April 2006

AbstractThe present paper examines whether leaves subjected to heat or salt pretreatment are better adapted to heat shock than untreated leaves. Such adaptation could result from either acquired thermo‐stability and/or better recovery. The rates of metabolic processes such as 14CO2 fixation, 14C‐leucine incorporation into the TCA insoluble fraction, 32P incorporation into phospholipids and 36Cl efflux were used as indicators of adaptability. It was found that pretreatments (heat or salt) protect leaves only slightly against the short‐term effects of a heat treatment, but have a pronounced effect on recovery. Cytokinin level was reduced by heat shock, and as in the case of metabolic response, pretreatment had no effect on this reduction.
Lower and Upper Critical Zinc Levels in Relation to Cotton Growth and Development
Authors: OHKI KENNETH 
Published: April 2006

AbstractSolution culture experiments in the greenhouse were conducted to determine the lower and upper critical Zn levels relative to early cotton (Gossypium hirsutum L.) growth and development. Upland cotton ‘Coker 310’ was grown in nutrient solution with fourteen Zn levels ranging from 0 to 10,000 μg/liter. The plants were grown for 31 days, harvested and analyzed for Zn.At Zn levels of less than 20 μg/I, top dry weight, root dry weight, plant height, node number and squares produced were reduced as compared to plants supplied with adequate Zn. Toxicities were induced at 2000 μg/I and higher. Root dry weight was not influenced by Zn levels to 10,000 μg/I. The lower critical Zn levels where Zn is required at a minimum concentration for maximum growth were from 8 to 11 μg/I in blades 1 through 5, respectively. The upper critical Zn levels where maximum Zn concentration in blade tissue can be tolerated for maximum growth were from 130 to 300 μg/g for blades 1 to 5, respectively. Blade 3, the recently matured leaf, was selected as the representative tissue for analysis. The lower and upper critical Zn levels in blade 3 were 11 and 200 μg/g, respectively.
Isolation and Partial Characterization of DNA in Capsular Preparations of Rhizobium trifolii
Authors: WULLSTEIN L. H. , BRUENING M. L. , WULLSTEIN B. M. , SHERWOOD M. 
Published: April 2006

AbstractThe capsular polysaccharides from thymidine‐(methyl‐3H) labeled cultures of Rhizobium trifolii; strain 162S7 (Nitragin Co.) were centrifuged from bacterial cells and collected by ethanol precipitation. Following the addition of unlabeled carrier nucleic acids, labeled DNA, termed cap‐DNA, was isolated from the capsular polysaccharides. Cap‐DNA absorbed maximally at H‐260 nm and was DNase sensitive. Approximately 11 μg of 3H‐cap‐DNA were consistently isolated per liter of 48 h cultures. Cap‐DNA production was generally synchronized with the synthesis of the capsular polysaccharide and bacterial growth, attaining maximum recoverable amounts in 48 h cultures. By five days of culture growth, significant decreases in the amount of recoverable cap‐DNA were noted. The presence of label in the cap‐DNA demonstrated that the cap‐DNA originated via de novo synthesis by the Rhizobium cells rather than from an anomalous source. The cap‐DNA and intracellular Rhizobium DNA had similar buoyant densities of p= 1.719, indicating that cap‐DNA arose specifically from the intracellular DNA. In 48‐h cultures the specific activity of the cap‐DNA was about one‐third that of the intracellular DNA. This implies intracellular DNA was released during early growth with a relatively low specific activity which diluted the isotopic label of DNA released later. The evidence suggests lysogeny was the principal release mechanism.
The effect of Aging on Ion Uptake by Excised Barley Roots
Authors: JACOBSON L. , YOUNG L. C. T. 
Published: April 2006

AbstractWhen excised barley (Hodeum Vulgare L.) roots were aged, the rate of uptake of K and C1 increased raching a maximum in about 14 to 18 h. At its maximum the uptake rate was approxiamately twice that of the freshly excised root materila. Respiratory activity declined markedly during the aging period. Although excision was an essential requirement for uptake enhancement, washing was not. Both the uptake and aging processes were shown ot be unresponsive to the presence or absence of Ca in the tratment solutions. Because of cation exchange properties, the change in the total cation content of the root material was a more meaningful measure of the metabolically mediated cation uptake than was the change in content of the test cation itself. The pluggin of xylem vessels with protein and pectin‐like substances was observed to increase with aging. It is proposed that the occlusion of the vessels may account for an apparent increaase in uptake since the obstruction could reduce a concurrent loss of ions through the cut ends of the root segments.
Rapid Effects on Ion and Water Uptake Induced by Changes of Water Potential in Young Wheat Plants
Authors: ERLANDSSON GUNVOR 
Published: April 2006

AbstractThe effect of rapid changes in the water potential of the root medium or the atmosphere was investigated with particular respect to water and ion uptake in young wheat plants. Either PEG 400 or PEG 6000 were added to the nutrient solution, so that the water potential was decreased from about 0 to –5 bars and –13 bars, respectively. Both water and ion uptake immediately decreased when the water potential of the medium was reduced. By raising the humidity around the shoots from 1400 N m−2 (60% RH) to about 2300 N m−2 (100% RH) water uptake decreased, whereas ion uptake transiently increased. If sodium chloride was added to reduce the water potential of the mutrient solution, ion uptake was found to decrease to essentially the same level as when PEG was used. It is suggested that a change in the water potential of the plants has effects on the active‐ion‐transport mechanism.
Metabolism of Gibberellin A4 by Vegetative Shoots of Douglas Fir at Three Stages of Ontogeny
Authors: WAMPLE R. L. , DURLEY R. C. , PHARIS R. P. 
Published: April 2006

AbstractVegetative shoots of coastal Douglas fir [Pseudotsuga menziesii (Mirb.) Franco] seedlings rapidly metabolized 1,2[3H]‐gibberllin A4 (GA4) to GA2, GA34 and 6 unknown acidie, ethyl acetate‐soluble compounds. The kinetics of formation of each compound depended upon the stage of ontogeny, metabolism being most rapid during bud set and bud break and least rapid during elongation. Translocation of radioactivity was greatest at the bud set stage. By hour 72 large amounts (65%) of neutral, ehter‐soluble compunds were formed at the stage of bud break and lesser, but significant amounts (40%) at bud set. Less than 15% of the radioactivity went into neutral ether during the elongation stage. Douglas fir appears to have an efficient system for con‐version of the relatively non‐polar GA34. This, coupled with the formation of neutral, ether‐soluble and acidie, n‐butanol‐soluble substances, may regulate the effective level of biologically active exogenous and/or endogenous GAs in this conifer.
The Recovery of Cytokinins during Extraction and Purification of Clubroot Tissue
Authors: DEKHUIJZEN H. M. , GEVERS Ch. Th. 
Published: April 2006

AbstractLosses of one naturally occurring cytokinin (zeatin) and one synthetic cytoknin (kinetin) were determined during purification of turnips (Brassica compestris) infected by Plasmodiophora brassicae (clubroot). A known amount of zeatin and 8‐14C‐kinetin was added after homogenization of plant material in ethanol or water. The commonly used practice to purify the aqueous residues of the homogenate by partitioning with petroleum ether was omitted because of emulsion formation. Losses due to emulsion formation and occlusion of 8‐14C‐kinetin into non‐water soluble plant material could be prevented by extractionof clubroot tissue with water instead of ethanol. To minimize enzyme activity the aqueous homogenate was kept at 100°C for 5 min. High molecular weight compounds were removed by dialysis against water and the diffusible fraction was partitioned with n‐butanol at pH 8.2.It was shown that a rapid evaporation of n‐butanol under reduced pressure at high temperature caused less breakdown of 8‐14C‐kinetin than prologned treatment at a low temperature.To minimize breakdown to zeatin riboside the butanol fraction was purified further on cation cellulose‐phosphate exchanger instead of on strong acid Dowex H+. 8‐14C‐kinetin was separated from zeatin by column chromatography on Sephadex LH20, and yielded 86% of the amount originally added to a plant homogenate.The zeatin containing fractions were further purified on thin layer chromatography (TLC) silicagel plates and injected into a high pressure liquid chromatograph. A yield of 60% could be estimated from the amount (15 μg) orignally added to 50 g clubroot tissue.
Effect of Salinity and Potassium on the Uptake of Nitrogen and on Nitrogen Metabolism in Young Barley Plants
Authors: HELAL M. , KOCH K. , MENGEL K. 
Published: April 2006

AbstractIn a solution culture experiment with 4‐week‐old barley plants (variety Villa) the influence of NaCl salinization and of KCl additions on the uptake and turnover of labelled N (15NH415NO3) was studied. Labelled N was applied for 24 h at the end of the growth period.Salinization impaired growth and uptake of labelled N. The incorporation of labelled N into the protein fraction, however, was improved by NaCl salinization. Additions of KCl to the nutrient solution diminished the negative effect of NaCl salinization on growth. At both NaCl salinization levels (60 and 120 mM) K additions favoured the uptake of labelled N and particularly its incorporation into the protein fraction.It is suggested that the negative influence of the NaCl stress is not primarily due to an impaired protein synthesis, but is possibly caused by a deterimental effect of Na on other metabolic processes.
Blue Light Induction of Barley Leaf Unfolding. A Phytochrome Reaction?
Authors: DEUTCH BENTE , DEUTCH† BERNHARD I. 
Published: April 2006

AbstractLow‐energy blue light (450, 475 nm) has been found to induced unfolding of etiolated barley leaves (Hordeum rulgare cv. Ingrid). This induction can be reversed by far‐red light. Barley leaf unfolding is normally stimulated by red light, reversed by far‐red light, and can be considered to be a typical phytochrome controlled response. It is possible to explain the effects by red and blue light as mediated by the same photoreceptor. The phototransformation of this pigment results in two forms, P2 and P4, to which physiological activity can be ascribed. The red and blue light affect different steps in a cyclical photoconversion. Calculated theoretical dose response curves are presented for such a model in agreement with the experimental data.
Recovery of Cytokinins from Cation Exchange Resins
Authors: VREMAN HENDRIK J. , CORSE JOSEPH 
Published: April 2006

AbstractCytokinins exhibit great affinity for the polystyrene matrix of Dowex‐50 cation exchange resins. Model experiments showed that only c. 20% of the applied 2‐methylthio‐trans‐zeatin and c. 70% of the trans‐zeatin are eluted from AG 50W columns with six bed volumes of 1 N NH4 OH. Inclusion of 70% (v/v) ethanol in the eluant increases the recovery to c. 55 and 85% respectively. No additional recovery was obtained upon continued elution to 14 bed volumes. Similar experiments with Duolite CS‐101, a weak acid cation exchange resin with acrylic matrix, showed that c. 95% of the applied 2‐methylthio derivatives of isopentenyladenine and zeatin are recovered from the resin with six bed volumes of 70% (v/v) ethanol (pH 10) or 1 N NH4OH in 70% (v/v) ethanol. The less modified cytokinins, isopentenyladenosine and ribosylzeatin, are recovered completely under these conditions. Recovery of cytokinins was determined by means of high‐pressure liquid chromatography of the column eluates.
Veränderungen der Aktivitäten von Glutamatdehydrogenase, Malatdehydrogenase und Isocitratdehydrogenase im Verlauf des Wachstums batchvermehrter Zellsuspensionskulturen von Pisum unter Langtag‐ und Dauerdunkelbedingungen
Authors: PAHLICH E. , MAYWALD H. , HARMS H. 
Published: April 2006

AbstractChanges of the Specific Activities of Glutamate Dehydrogenase Malate Dehydrogenase and Isocitrate Dehydrogenase in Light‐ and Dark‐Grown Suspension Cultures of Root Cells from Pisum sativum.
The Movement and Physiological Effect of Indoleacetic Acid Following Point Applications to Root Tips of Zea mays
Authors: DAVIES PETER J. , DORO JOSEPH A. , TARBOX ANDREW W. 
Published: April 2006

AbstractPinpoint applications of labeled and non‐labeled indoleacetic acid (IAA) on resin beads were made, without injury, to vertical roots of intact seedlings of Zea mays. Points of application were at the extreme tip of the root, 0.5, 2 and 5 mm from the root tip. The movement of label and bending of the roots was recorded. Radiolabel was found to move basipetally from the extreme tip and 0.5 mm applications to a similar extent, reaching 8 mm from the tip. The level of label in the growing zone after 4 h was 10% of that found in the extreme tip. Movement from 2 and 5 mm applications was equal in both directions. Higher amounts of non‐labeled IAA caused bending towards the point of application if applied at 0.5 or 2 mm but not at 5 mm from the tip. It is proposed that any endogenous IAA in the root cap could move to the growing zone and cause a unilateral inhibition of growth, provided that it was in the same transport pool as the exogenously applied IAA.
Changes in the Amount of Complex Lipids in the Seeds and in the Pericarp during the Development of Ivy Fruit (Hedera helix)
Authors: GROSBOIS MICHÈLE 
Published: April 2006

AbstractBy a combination of thin‐layer chromatography and gas liquid chromatography, a complete study of the development of the different lipid classes and of their fatty acids, during the development of the fruit of Hedera helix L., the English Ivy, has been achieved. In any part of the fruit observed, at any particular stage, the phospholipids and the neutral lipids are the most abundant lipid classes. They accumulate during the entire process of maturation, whereas significant changes occur in their relative proportions, phospholipids being largely dominant until fruit blackening.The accumulation of fatty acids during maturation is characterized by large amounts of C18:1 in the neutral lipids, especially in the seed, where petroselinic acid (C18:1Δ6) reaches 86% of the total fatty acids. To a smaller extent, the phospholipids also accumulate and thus have the character of reserve molecules. However, their composition remains more stable, which relates them to the “structural lipids” such as galactolipids that maintain their characteristic fatty acid composition, despite the radical changes occurring in the fatty acid metabolism during fruit ripening.
Callus Induction by (2‐Chloroethyl) Phosphonic Acid on Cultured Cotton Ovules
Authors: LEE HSU CECILIA , STEWART JAMES McD. 
Published: April 2006

AbstractThe response of cultured cotton (Gossypium hirsutum L.) ovules to the ethylene releasing growth regulator, (2‐chloroethyl) phosphonic acid (ethephon), was measured. Control ovules grown on a complete liquid medium without hormones continued the differentiation normal for cotton, although at a slower rate than in vivo. When ethephon was added to the medium, normal organ and fiber development was inhibited but callus was induced from the micropylar end of the ovule. The callus was extremely friable and produced many free cells in the culture medium. Dry weight of the callused ovules increased over 4‐fold and total cell number increased 56% over the controls. Apparently ethylene released from the ethephon stimulated both cell division and cell expansion in forming the callus.
Water Stress in Plants
Authors: RASMUSSEN OLE S. 
Published: April 2006

AbstractThe abscisic acid (ABA) content was determined quantitatively in the leaves from wilted and unwilted tomato plants (Lycopersicon esculentum Mill. CV. Revermun) by the use of the wheat coleoptile test and gas‐liquid chromatography (GLC). Plants which have received an insufficient daily water supply for 18 days showed adaptation to wilting conditions. The plants adjust to the added amount of water by regulating their water loss through transpiration. The concentration of ABA was not higher in the leaves of plants adapted to water stress than in plants that were watered abundantly. Wilted detached leaves and leaves from rapidly wilted intact plants showed the well‐known reaction by increasing the ABA level. A possible role of ABA in the early stages of the adaptation process is discussed.
Properties of Phenylalanyl‐tRNA Synthetase and Phenylalanine Ammonia‐lyase of Pine Suspension Cultures
Authors: COWLES JOE R. , FOWLER JO ANN 
Published: April 2006

AbstractPhenylalanyl‐tRNA synthetase and phenylalanine ammonia‐lyase activities were demonstrated in partially purified extracts of pine (Pinus elliottii) suspension cultures. The optimum pH for the phenylalanyl‐tRNA synthetase reaction was 7.5 and the optimum ATP and Mg2+ concentrations were 1.0 and 15 mM respectively. Pine, calf liver and yeast tRNA were inadequate substitutes for pea tRNA in the synthetase reaction mixtures. The optimum pH for the phenylalanine ammonia‐lyase reaction was 9.0. The Km for phenylalanine was approximately 6.6 × 10−5M. The activity of both enzymes in the partially purified extracts was unstable on storage.