bluuebunny/crossref_metadata_2025_split huggingface dataset:
Ascorbic Acid and Heterocyst Development in the Blue–Green Alga Amabaema ambigua
Authors: WAHAL C. K. , BHATTACHARYA N. C. , TALPASAYI E. R. S. 
Published: April 2006

AbstractThe nitrogen–fixing blue–green alga Anabaena ambigua was grown in a medium which contained either ammonium chloride as nitrogen source or molecular nitrogen. In the latter case the alga produced heterocysts. The material was analysed for ascorbic acid, dehydro‐ascorbic acid and diketogulonic acid. The amount of a,scorbic acid was found always to he higher in the alga grown with molecular nitrogen. When the alga grown with combined nitrogen was transferred to the medium lacking it, there was an increase in the ascorbic acid content. Conversely, when material cultured on the nitrogen–free medium was suspended in the medium containing ammonium chloride, there was a decrease in the cellular ascorbic acid. Esogenously added ascorbic acid, up to 0.5 mg per ml, increased the heterocyst frequency to nearly three times that of the control. D–isoascorbic acid, an analogue of ascorbic acid, also showed an enhancement of heterocyst production.Algal extracts were fractionated by poiyacrylamide electro–phoresis, and the presence of ascorbic acid oxidase was detected on the gels. Two bands, with Rf values 0.34 and 1.0, were found to give positive test: for the enzyme. The total enzyme activity was 16.7 % higher in cells grown with molecular nitrogen than in those grown with combined nitrogen. The exact location of the enzyme in the alga ist not known although the heterocysts were earlier shown to contain ascorbic acid. Cytochemical tests, however, indicated strong per–oxidase activity in the heterocysts.
Effect of Preparation Method on the Induction of (Sodium + Potassium) –Activated Adenosine Triphosphalase from Sugar Beet Root and its Lipid Composition
Authors: HANSSON G. , KUIPER P. J. C. , KYLIN A. 
Published: April 2006

AbstractThe (Na++K+)–stimulation of the ATPase activity in a paniculate fraction from sugar beet roots was compared after inducing treatments with dithiothreitol (DTT), cystein or deoxycholate (DOC). Protection of SH groups by cystein or DTT increased the specific activity at the optimal Na: K ratio (25 :25 mM) with a factor of about 5 as compared to the untreated fraction, and with a factor of about 3 as compared to particles treated with DOC. DTT acted chiefly at the optimum ratio of Na : K (25 :25 mM), whereas a less specific stimulation at any proportion of the couple Na : K was observed after treatment with DOC or cystein. A combined treatment (DOC + DTT) led to inactivation of the DTT effect.Treatment with DTT resulted in a loss of lipids, which were replaced by water, but otherwise little swelling took place. The loss of lipids was almost exclusively due to loss of phospholipids, and among these the zwitterkonic phos–phatidyl choline and phosphatidyl ethanolamine were affected more than the acidic phosphatidyl glycerol or phosphatidyl inositol. The sulfolipid was maintained within the particles. The combined treatment “with (DOC + DTT) led to further losses of lipid material at the same time as strong swelling took place. As compared to the treatment with DTT alone, the additional loss of lipids occurred mainly from the (sterol glycoside + cerebroside + digalactosyl diglyceride –fraction) and from the solfolipid, with some losses also from the (pigments + neutral), phosphatidyl choline and phosphatidyl glycerol fractions.The results are in agreement with our earlier data, which also show that lipid fractionation is important for the revealing of (Na+ 4– K+)–stimulated ATPase activity, possibly because of the negative electric charge of the sulfolipid, which is characteristic for the induced preparations and which may be connected with the specific site of stimulation by the cations.
The Effect of Magnesium and Calcium Ions on Adenosine Triphosphatases from Wheat and Oat Roots at Different pH
Authors: KYLIN A. , KÄHR M. 
Published: April 2006

AbstractMicrosomal fractions from wheat (Triticum vulgare) and oat (Avena sativa) roots were used to study Mg2+ and Ca2+ activated adenosine triphosphatases, their dependence of pH, and how Mg2+ and Ca2+ compete or add in stimulation and inhibition.Wheat gives a high proportion of Ca2+ stimulated ATPase. Less effect is obtained with Mg2+. The characteristics of oar ATPase are the reverse.The ATPase from the wheat roots depends on the mineral nutrition. A kinetïc analysis shows one site, where Mg2+ and Ca2+ at low concentrations (or complexes between the di‐valents and ATP) cooperate in the activation of the ATPase. The action of this site is more dearly expressed at pH 6.0 than at 6.8, and more clearly in the preparations from low salt roots than in those from high salt conditions. In another site, which is particularly evident in preparations from high salt roots tested at pH 6.8, high concentrations of Mg2+ inhibit the ATPase; this inhibition is competitively relieved by Ca2+. The specific activity of the ATPase from high salt roots of wheat is higher than that from low salt roots, although the amount of protein of the fraction studied remains the same, when calculated per g fresh weight of the roots.
Occurrence of Inverted Water Potential Gradients between Soil and Bean Roots
Authors: TAERUM RAGNAR 
Published: April 2006

AbstractMeasurements with a pressure chamber were made of the xylem water potential of leaves, shoots and roots from bean plants (Pkaseolus vulgaris L. cv. Processor) grown with a 12 hour dark period and natural or artificial light conditions during the day. The water potentials were measured at the end of a dark period and during the light period.Measurements taken at the end of the dark period indicated normal potential gradients within the soil/plant system (leaf < shoot < root < soil), when the matric potential of soil water was relatively high (above −0.02 bar), and the gradients then also remained normal during the day (natural light). When the soil water potential was −1 bar or lower in the morning, however, the root xylem water potential was higher than the soil water potential; at very low soil water potentials (< −4 bar) it remained higher during most of the day. In this case also leaf and shoot xylem water potentials were higher than the soil water potential in the early morning, although decreasing rapidly in daylight.Under artificial light, both leaf and root water potentials were higher than the soil water potential throughout the whole diurnal cycle when the latter potential was below −4 bar.From measurements of stomatal diffusion resistance, transpiration, relative water content of leaves and of changes in the matric potential of soil water, it was concluded that when the matric potential of soil water was low, water could be taken up by the plant against a water potential gradient. Because leaf xylem water potential was always lower than root xylem water potential, the mechanism involved in the inversion of water potential gradient must be localized in the roots, and probably related to ion uptake. Symbols and abbreviations used in the text: Ψ: Plant water potential (thermocouple psychrometer); Ψx: Xylem water potential (pressure chamber); Ψs: Osmotic potential of xylem sap; Ψm: Matric potential of soil water; RWC: Relative water content.
Root Formation in Pea Cuttings
Authors: ERIKSEN E. NYMANN 
Published: April 2006

AbstractThe importance of the active shoot meristems for root formation in cuttings has been investigated through disbudding, decapitation or both disbudding and decapitation of pea cuttings at different time intervals after the removal of the cutting.Decapitation and disbudding within the first 4 days after cutting drastically reduce both the number of rooted cuttings and the number of roots per cutting. Treatment 5 to 6 days after cutting has little or no effect on the root formation or the number of roots per cutting.Redaction in rooting is explained by the removal of the production center(s) for the growth promoters which are necessary for root formation. It is deduced from the results obtained that the initiation phase in pea cuttings is about four days.The author is much indebted to the Department of Plant Physiology of the Royal Veterinary and Agricultural University, Copenhagen, for permission to use its growth chambers during the present investigations.
Triterpeneglycosideg as Inhibitors of Fungal Growth and Metabolism
Authors: OLSEN ROLF A. 
Published: April 2006

AbstractErgosterol was found to be the main sterol in the mycelia of Opbiobolus graminis, Neurospora crassa, and Aspsrgillus niger, A correlation was found between the amount of sterols in the mycelia of different fungi and the inhibitory effect of aescin. Aescin treatment caused a reduction of the amount of extractable sterols in the mycelia. The sterols seemed to be located mainly in the plasma membranes, and only trace amounts were Found in the mitochondrial membranes.The relative amount of sterols in the plasma membrane was found to be higher in O. graminis than in N. crassa and A. niger.Ca2+ interfered with the interaction, of sterols and aescin. In N. crassa the decreased inhibitory effect of aescin in the presence of Ca2+ was due to the reduced binding of the inhibitor to the sterols in the plasma membrane.
Effects of Kinetin, Gibberellins and (±) Abscisic acid on the Germination of Lettuce (Lactuca sativa)
Authors: REYNOLDS T. , THOMPSON P. A. 
Published: April 2006

AbstractGermination responses of achenes of lettuce (Lactuca sativa L, cv. Arctic King) to treatment with kinetin, gibbe‐rellins and abscisic acid were examined over a range of temperatures: in both light and dark.Kinetin (0.1–10 mg/l) strongly promoted germination at temperatures above 27±C in continuous light or after short periods of illumination during the early stages of imbibition. It also relieved the inhibitory affects of abscisic acid in these conditions. In total darkness however kinetin treatment resulted in only a minor promotive effect.Treatment with gibberellic acid (A3) or a mixture of gibberellins A4 and A7 were much less effective in promoting germination at higher temperatures of lettuce achenes exposed to light but were strongly promotive in the dark.
Slime of Myxococcus virescens
Authors: STAHL STEN 
Published: April 2006

AbstractThe slime excreted by two strains of Myxococcus virescens during growth in liquid casitone medium was studied. Strain S1H, unable to grow in dispersion, excreted slime during growth later than strain D11, which grows in dispersion. Slime was precipitated from the cell‐free culture solution with ethanol and the crude precipitate fractionately dissolved using first pH 5,4 and then pH 9.0 for the remainder of the precipitate. Comparatively more material from strain S1H than from strain D11 belonged to the pH 9.0 fraction. The fractions thus obtained were dialyzed and then lyophilized.The composition of the slime preparations varied with the density of the harvested cultures. The slime fraction dissolved at low pH contained 12–18 % (w/w) Folin reactive material, 2–4% lipid and 5–30% anthrone positive material (glucose equivalents). The fraction soluble at pH 9.0 was richer in Folin positive material. About 25% of the proteolytic activity in the culture solution was recovered in the slime preparations. No DNA was detected in the slime, unless the cultures were harvested daring the phase of decline.The high polymers of the slime were separated from material of low molecular weight and coprecipitated media constituents by gel filtration on Sepharose 2B. The relative amount of the high polymers increased during growth, although they seemed to be degraded in the culture during the phase of decline. The polymer had a molecular weight of about 20 million. In most preparations: it was Folin positive.
Permeability of Bacteria to Inorganic Cations. A Comparison between a Psychrophilic Achromobacter Strain and Escherichia coli
Authors: LEDEBO INGRID , LJUNGER CLAES 
Published: April 2006

AbstractThe permeability of a psychrophilic Acbromobacter strain to the chlorides of Na, K, Mg and Ca was investigated with light‐scattering technique. Comparisons, were made with cells of Escherichia coli B. Cells of both strains suspended in “water were plasmolyzed by 0.1 or 0.2 M solutions of MgCl2 or CaCl2 without subsequent deplasmolysis. NaCl or KCl also plasmolyzed the cells, but deplasmolysis followed.” When suspended in growth medium E. coli became completely de‐plasmolyzed., whereas the psychrophile still excluded MgCl2 and CaCl2 to a great extent. The plasmolysis and deplasmolysis were reversible. Electron micrographs of the psychrophile exposed to CaCl2 confirmed the presence of plasrnolysis.
Cyclic Mononucleotide‐Gibberellin Interactions in the Flowering and Proliferation of the Long‐Day Plant Lemna gibba G3
Authors: KESSLER BEZALEL , STEINBERG NATANAEL 
Published: April 2006

Abstract3′,5′‐cAMP stimulates flowering of Lemna gibba G3 under inductive long‐day conditions and enhances flower onset. 3′,5′‐cAMP has no influence on frond production.2′,3′‐cGMP increases markedly the proliferation of fronds and inhibits flowering. The effect of 2′,3′‐cGMP on frond multiplication is photoperiodically independent; under short‐day conditions 2′,3′‐cGMP replaces in fact the requirement for inductive long‐day conditions.2′,3′‐cGMP increases the total amount of DNA per frond. This accumulation of DNA precedes by 2–3 days the 2′,3′‐cGMP related increase in frond formation.The results are discussed in the light of the hypothesis that the active cyclic mononucleotides exert their effects on multiplication and flowering at the level of DNA.
Art und Menge der Ausscheidung 14C‐markierter Verbindungen bei Chlorella pyrenoidosa unter dem Einfluss des osmotischen Drucks der Nährlösung
Authors: WELLER Von H. , HDFNER W. , LINSER H. 
Published: April 2006

Abstract Chlorella pyrenoidosa was labelled by 14CO2 and the nature and amount of excreted organic compounds in nutrient media of different osmotic pressure were determined after a 24 h period. The total rate of excretion of organic bound 14C was about 4 μg 14C per mg harvested algal dry matter or 1% of the total 14C content of the algae at the beginning of the excretion period. The main compounds found in the excretions were unidentified substances with a molecular weight higher than 700, amino acids, organic acids and sugars.The osmotic pressure of the nutrient medium did not affect the total amount of the organic excretions. However, the excreted amounts of some specific compounds differed in respect to the osmotic conditions of the nutrient medium.
Levels of Indol‐3yl‐acetic Acid and Acid Inhibitors in Green and Etiolated Bean Seedlings (Phaseolus vulgaris)
Authors: TILLBERG ELISABETH 
Published: April 2006

AbstractIndol‐3yl‐acetic acid (IAA) was identified in Phaseolus vulgaris L. Shoot tissue of seedlings, exposed to light for 5 days, had a higher level of IAA than etiolated seedlings of the same age. The content of IAA increased in green seedlings during light treatment for 5–12 days. No increase could be measured in dark‐grown seedlings. Inhibitory substances appeared at different Rf‐values. The main part was identical to the inhibitor‐β complex and occurred in a higher amount in light‐grown seedlings than in etiolated taller ones. One part of the inhibitor‐complex appeared to be abscisic acid (ABA). It is suggested that both IAA and acid inhibitors may play an important role in the control of stem growth and differentiation, although light effects on other hormones and regulatory systems cannot be ignored.
Auxin Balance in the Avena Coleoptile
Authors: RAJAGOPAL R. , LARSEN POUL 
Published: April 2006

AbstractColeoptiles of Avena possessed the capacity to degrade infiltrated indole‐3‐acetic acid (IAA). This activity decreased along the length of the coleoptile from apex to base on the bases of fresh weight, dry weight and protein; the apical 1 cm segment degraded more IAA than segments from other parts of the coleoptile. The naturally occurring inhibitor of the IAA oxidase activity increased in concentration up to 20 mm from the coleoptile apex; beyond, it decreased gradually towards the base. The spatial distribution of this inhibitor does not explain the gradient in IAA oxidase activity. Growth in length of the coleoptile and the IAA inactivating capacity of the apical 1 cm segment, increased 5‐ and 4,4‐fold, respectively, between the ages of 70 and 130 h; but auxin secretion into agar platelets by the apical 2 mm of the coleoptile registered only a 2.7‐fold increase. Deseeding and derooting the seedlings reduced the subsequent growth, diffusible auxin content and the IAA oxidase activity of the coleoptiles; derooting proved to be more deleterious than deseeding. A parallel reduction was evident in auxin content and IAA degrading activity following these treatments. Application of the cytokinin 6‐benzylaminopurine (BAP) to coleoptiles of derooted seedlings failed to influence their capacity to degrade IAA. Nor was the activity of the aldehyde oxidase, which converts indole‐3‐acetaldehyde (IAAld) to IAA, affected by such treatment.
In vitro Studies on Pinus
Authors: KONAR R. N. 
Published: April 2006

AbstractHypocotyl tissue from Pinus gerardiana was established in culture on White's basal medium supplemented with 2 % sucrose, 10% (v/v) coconut milk, 500 mg/l casein hydrolysate and 1 mg/1 2,4‐dichlorophenoxyacetic acid (2,4‐D).Various organic and inorganic nutrients were studied in order to determine the specific nutritional requirements of the tissue in vitro. Sucrose, glucose and maltose were equally effective as fixed carbon sources. The inorganic nutrient combination of White's medium was found to be better than that of Murashige and Skoog's medium. White's modified basal medium supplemented with coconut milk, casein hydrolysate and 2,4‐D was the most successful nutrient combination. Glutamine was as effective as casein hydrolysate in promoting growth of the tissue.
The Role of Auxin Metabolism in Root Meristem Regeneration by Pinus lambertiana Embryo Cuttings
Authors: GREENWOOD M. S. , HARLOW C. , HODGSON H. D. 
Published: April 2006

AbstractSince the existence of root promoting substances that consist of a complex between auxin and another molecule has been suggested, we have examined the role of auxin conversion products in root regeneration by Pinus lambertiana embryo cuttings. Auxin conversion products were detected using radioactive forms of the auxins IAA (indoIe‐3‐acetic acid), NAA (a‐napthaleneacetic acid) and 2,4‐D (2,4‐dichlorophenoxyacetic acid). 10−7M NAA was more effective than 10−6M IAA at promoting rooting, yet it formed conversion products much less rapidly. Also continuous exposure to IAA was necessary for optimum root formation. Based on these and other findings, we conclude that free auxin, and not the conversion products we detected, is essential to root meristem formation.
Measurement of the Five Enzymes which Convert Chorismate to Tryptophan in Wheat Plants (Triticum aestivum cv. Kalyansona)
Authors: SINGH MAHENDRA , WIDHOLM J. M. 
Published: April 2006

AbstractConditions are described for measuring anthranilate synthetase, anthranilate‐PRPP‐phosphoribosyl transferase, N‐5′‐phosphoribosyl anthranilate isomerase, indole‐3‐glycerol phosphate synthetase and tryptophan synthetase in crude extracts from Triticum aestivum (wheat) plants. Only the last enzyme has been measured before in extracts from green plants. The extractable quantities of each enzyme in all plant parts at all stages of growth were sufficient to synthesize the amount of tryptophan present within the same tissue in 48 h. Anthranilate synthetase activity was the lowest of the five enzyme activities and was the only one inhibited by tryptophan in vitro, indicating that this enzyme may be the control point in tryptophan biosynthesis in wheat plants.
Abscisic Acid in Prunus Trees: Isolation and the Effect on Growth of Excised Shoot Tissue
Authors: FEUCHT W. , KHAN M. Z. , DANIEL P. 
Published: April 2006

AbstractThe abscisic acid content of the mature shoot tissue of vigorous Prunus avium, medium sized Prunus cerasus and dwarfing Prunus cerasus self (S) was estimated by spectropolarimetry and gas chromatography. There is no correlation between the levels of ABA found in the tissue and the dwarfing potential of the trees investigated. However, Prunus arium stem tissue shows the lowest sensitivity to ABA, whereas the explants of normal and dwarfing Prunus cerasus exhibit a stronger inhibition.
Differential Absorption, Translocation and Metabolism of Metribuzin [4‐amino‐6‐tert‐butyl‐3‐(methylthio)‐as‐triazine‐5(4H)one] by Soybean Cultivars
Authors: SMITH A. E. , WILKINSON R. E. 
Published: April 2006

AbstractSoybean (Glycine max (L.) Merr.) cultivars have been reported to range in tolerance to injury by 4‐amino‐6‐tert‐butyl‐3‐(methylthio)‐as‐triazine‐5(4H)one (metribuzin), from tolerant (e.g.‘Bragg’) to susceptible (e.g.‘Coker 102’ and ‘Semmes’). ‘Bragg,’‘Coker 102’, and ‘Semmes’ soybeans were grown in sand subirrigated with nutrient solution containing labelled (14C‐carbonyl metribuzin) and nonlabelled metribuzin to determine cultivar variability in absorption, translocation, and metabolism of metribuzin. Plants were periodically harvested, autoradiographed, and radioactivity in tissue extracts quantified. Data indicated that all 3 cultivars readily absorbed and translocated metribuzin. However, ‘Bragg’ tissues accumulated greater quantities of metribuzin metabolites than the other two cultivars. The major 14C‐containing metabolite in ‘Semmes’ and ‘Coker’ roots and stems was 6‐tert‐butyl‐as‐triazine‐3‐5‐(2H,4H)‐dione, whereas the major 14C‐metabolite isolated from‘Bragg’ roots and stems was a glucose conjugate. Results indicated that differential‐intraspecific responses to metribuzin may result from differential capacities for herbicide detoxification by conjugation.
Oscillatory Transpiration and Water Uptake of Avena Plants
Authors: BROGÅRDH TORGNY , JOHNSSON ANDERS , KLOCKARE RUNE 
Published: April 2006

AbstractThe oscillatory transpiration of 6 days old Avena plants was investigated with respect to the water potential of the root medium. The desired water potential was obtained by means of mannitol solutions.When the water potential was lowered (“mannitol step”), the amplitude of the oscillations decreased. Below –3.0 bars no oscillations persisted. A detailed study was made of the phase changes of the oscillations caused by a short time decrease of the water potential of the root medium (“mannitol pulse”). The duration of these short term treatments was either 9.0, 3.0 or J.5 min.The experimental results are discussed on the basis of an electric analogue previously presented in the literature. Published simulations based on the model were in clear contrast to the present experimental results as well as to earlier results in the literature. However, simulations in the present paper showed that the model could explain the experimental results if suitable parameter values were chosen.